180 tstat and intake manifold temp [Archive] - Cherokee SRT8 Forum

: 180 tstat and intake manifold temp


timster
04-16-2007, 05:32 PM
I just got finished driving my beast for about an hour or so - mostly on the highway. The 180 Motorad/valucraft tstat works great on the freeway - consistant coolant temps never seem to exceed 190, and the oil temp, likewise, stays cooler than it did previously.

After parking the Jeep I popped the hood to check the reserve coolant levels to see if it needed any extra antifreeze since installing the stat. Out of curiosity, I also touched the intake manifold to see how hot it was. At first I just quickly brushed my hand over it since I thought it was gonna be pretty damn hot. To my surprise, it wasn't even hot at all. I was able to keep my hand on it as long as I wanted to without any discomfort at all. WTF, I'd say it was maybe about 70 degrees or so, which was amazing since I've read that it is supposed to get extrememly hot.

Anyways, it looks like I wont need to install my phenolic intake spacers from GSM. Has anyone else noticed this after installing their tstat?

timster
04-17-2007, 09:08 PM
so it's been 3 times now that I have checked the intake manifold after extensive driving. Seems like it doesn't heat up at all.. WTH?? Not sure if it is the 180 degree tstat causing this, or if it's the cool weather, or a combination of both, but this is weird..

I guess I'll have to wait till it gets hot up here in the NorthEast to see if the intake manifold temp is due to the weather.

OurZoo
04-17-2007, 11:56 PM
I keep forgetting to check the temp after driving, but I just got my spacers in the mail today.

Derwood98
04-18-2007, 12:23 AM
For those fan and stat mod followers. I had a thought on the way to work this morning. Obviously the Jeep engineers selected the components to (thermostats and relays) to achieve the best possible HP given specific conditions. As in refrigeration, we size our systems based on the worst case senarios. I have heard a few of you mention that you feel a little better response when the weather is cooler. I may not know much, but lowering your engine temp via jumpering the thermostats or putting a 180 degree stat doesn't seem to correlate with more HP. I am confused. HP comes from a dense fuel to air ratio along with compression, timing and a whole lot of other things. However, if you take an SRT8, designed to preform on the worst case senario, how does lowering the engine temp do anything for HP? When in fact it's the cooler more dense air combined with fuel which makes more HP? Not sure I follow the logic on these mods.

I have a 1996 Jeep Cherokee with a stage II Jet chip and it recommends a 180 degree thermostat because it changes timing, fuel to air ratios and a number of other things to make the engine run hotter. That's the only reason why a person would want to change the stat. I also put in a larger radiator because even with the cooler stat, the stock radiator could not disipate the additional heat generated by the upgrade. I really don't see this need in the SRT8's. Just my two cents. I could see making the change if you made drastic tuning changes like adding a turbo or super which by nature would make the engine work harder.

Inferno SRT8
04-18-2007, 04:50 AM
While driving the intake manifold should be warm or cool to the touch as all the air that is going thru the manifold is picking up the heat that the manifold has picked up.

When standing still for about 5 minutes is when you realize how bad the heat soak is on these, the manifold gets heat soaked and you can fry an egg on it. That 2-5 minutes when your waiting to stage at the track is when this is killing us, this is where the GSM or whatever spacers you want to use are going to help BIG TIME!

Dont be fooled the Tstat helps the engine run cooler and stronger while moving but once you stop that heat soak is killer. My spacers go on this week.

HoustonSRT-8
04-18-2007, 08:05 AM
Cooler thermostat = cooler motor = cooler intake = cooler intake charge = more hp

I have a 1996 Jeep Cherokee with a stage II Jet chip and it recommends a 180 degree thermostat because it changes timing, fuel to air ratios and a number of other things to make the engine run hotter.

Why would you want to make your motor run hotter? :confused:

cobrakid
04-18-2007, 08:25 AM
...according to some previous posts....the SRTs pull out timing in correlation
to vehicle temps to avoid detonation.

When it is 85*-95* outside this summer, I am sure I will be glad I have the 170 stat in.

OurZoo
04-18-2007, 09:11 AM
Last summer it 100 degrees 3 weeks straight in my hood. My commute to work is very unpredictable due to traffic. Los Angeles sucks for that reason. The tstat and the spacers should definitely help out.

GotStroke?
04-18-2007, 10:40 AM
For those fan and stat mod followers. I had a thought on the way to work this morning. Obviously the Jeep engineers selected the components to (thermostats and relays) to achieve the best possible HP given specific conditions. As in refrigeration, we size our systems based on the worst case senarios. I have heard a few of you mention that you feel a little better response when the weather is cooler. I may not know much, but lowering your engine temp via jumpering the thermostats or putting a 180 degree stat doesn't seem to correlate with more HP. I am confused. HP comes from a dense fuel to air ratio along with compression, timing and a whole lot of other things. However, if you take an SRT8, designed to preform on the worst case senario, how does lowering the engine temp do anything for HP? When in fact it's the cooler more dense air combined with fuel which makes more HP? Not sure I follow the logic on these mods.

I have a 1996 Jeep Cherokee with a stage II Jet chip and it recommends a 180 degree thermostat because it changes timing, fuel to air ratios and a number of other things to make the engine run hotter. That's the only reason why a person would want to change the stat. I also put in a larger radiator because even with the cooler stat, the stock radiator could not disipate the additional heat generated by the upgrade. I really don't see this need in the SRT8's. Just my two cents. I could see making the change if you made drastic tuning changes like adding a turbo or super which by nature would make the engine work harder.


When the PCM senses increased coolant/IAT temps, it pulls timing to avoid detonation.

generalconfusion
04-18-2007, 11:57 AM
Gentlemen......we did these tests last year!!! The cooler T-Stat is a PROVEN dyno tested mod performed and posted on the OC site and members on the LX site. Your overthinking this......it works.

Also, just for information....... since then, the dyno tests I did last summer, the average baseline horsepower on a Dyno Jet dyno both at GSM and Harmanmotive, for my truck were 333hp-340 depending on the configuration such as no filter, 180 degree temps, ice the manifold, first run vs 3rd run for heat soak, etc,etc. By the second or third run hp/tq starts to diminish. I had higher numbers at the XS Engineering 4 wheel DTS9000 dyno (during stock exhaust vs Mopar) but wanted to keep it apples to apples for this test so I went back to Harmans DynoJet.

Yesterday late afternoon I returned to Harmanmotives shop and wanted to test it since I had never run it with the headers/catback/ ported manifold/phenolic spacers and stock modifed cold air box as a combination......three back to back runs at 193 degrees....376hp/375tq each and every run!! Previous run at factory temps around 211-215 with stock airbox/stock exhaust was 332hp/339tq. That is a huge improvement for this combo over stock and no tune yet.

I will post those sheets tonight, all previous dyno runs are shown on the OC site under sgtstanko dyno runs. I'll run it at Irwindale Thursday to see if any improvements in times are seen.

Where is my B&G box?????

cobrakid
04-18-2007, 12:29 PM
.....congrats General!

I have a thought, when I went 12.85@104.5, I did a few of those online
dyno calculators based on that info and weighing 4920 with me in it on the line......

I kept coming up with 458ish? I assume that is flywheel estimated hp?

From what I have heard, you would lose about 15% through drivetrain etc,
prolly more with AWD....that would be over 380????????

I am thinking of this the wrong way or something?

I know a true dyno pull is different. ...believe me, you definately don't want
to run anything on a Mustang dyno. The numbers will piss you off.

I argued with a guy who swore that the Mustang dynos are the most accurate
...blah, blah, blah.....load correction, actual power....etc..etc.

I tried to tell him, if my buddy puts down "only" 750rwhp on his MustDyno, and
then goes to the track and runs 8.8@154 at 3270lbs, then something is not
right with his dyno.....it scientifically/physically takes X amount of hp & tq to
move a certain weight object a certain distance...PERIOD.

This is way off topic, I am just saying this for discussion and your thoughts.

HoustonSRT-8
04-18-2007, 12:36 PM
.....congrats General!

I have a thought, when I went 12.85@104.5, I did a few of those online
dyno calculators based on that info and weighing 4920 with me in it on the line......

I kept coming up with 458ish? I assume that is flywheel estimated hp?

From what I have heard, you would lose about 15% through drivetrain etc,
prolly more with AWD....that would be over 380????????

I am thinking of this the wrong way or something?

I know a true dyno pull is different. ...believe me, you definately don't want
to run anything on a Mustang dyno. The numbers will piss you off.

I argued with a guy who swore that the Mustang dynos are the most accurate
...blah, blah, blah.....load correction, actual power....etc..etc.

I tried to tell him, if my buddy puts down "only" 750rwhp on his MustDyno, and
then goes to the track and runs 8.8@154 at 3270lbs, then something is not
right with his dyno.....it scientifically/physically takes X amount of hp & tq to
move a certain weight object a certain distance...PERIOD.

This is way off topic, I am just saying this for discussion and your thoughts.
Did those calculators account for gearing?

DavesSRT8
04-18-2007, 01:13 PM
Agreed on cooler temps. Dragstrip times don't lie.

Stock:
13.378 @ 102.61
13.286 @ 102.81
13.308 @ 102.89

changed to 180 thermo, same track (Etown), almost exact same ambient temps, cooldown time, etc. (Dashhawk used to make sure temps were cooler). Efan turned on via switch (Hi side). 60 foot times were about the same also, 1.8-1.9 ranges

13.062 @ 103.67
13.040 @ 103.82
13.048 @ 103.83
13.077 @ 103.44

1/8th mile times went from 8.5's to low 8.3's.

So, very satisfied with a less than 20 dollar set of mods (thermo/fan switch) to get close to 3/10ths in quarter. These times indicate what generalconfusion is stating about what they saw in dyno pulls w/cooler temps - 50 hp or so. What I really like is consistency between runs, as it seems there is a point where timing is arbitrarily pulled when heat soaked, to avoid detonation (especially w/higher compression).

An amazing vehicle, extremely easy to bracket race. Just need a tuner to adjust timing, fuel and shift points/firmness and this is an easy low 12 second truck. (if not better). Took me quite a while and alot of practice to get my (sold) Lightning this low and consistent in times.


Dave
2007 JGCSRT8

Inferno SRT8
04-18-2007, 01:33 PM
Agreed on cooler temps. Dragstrip times don't lie.

Stock:
13.378 @ 102.61
13.286 @ 102.81
13.308 @ 102.89

changed to 180 thermo, same track (Etown), almost exact same ambient temps, cooldown time, etc. (Dashhawk used to make sure temps were cooler). Efan turned on via switch (Hi side). 60 foot times were about the same also, 1.8-1.9 ranges

13.062 @ 103.67
13.040 @ 103.82
13.048 @ 103.83
13.077 @ 103.44

1/8th mile times went from 8.5's to low 8.3's.




See this is what im saying, if I had my 180 Tstat and my spacer in when I ran my 12.53 it may have been a 12.00 flat. Track times dont lie, great write up Dave.

cobrakid
04-18-2007, 01:58 PM
...inferno.... you wouldn't have picked up that much dude!

Remember the go fast rule.....

The faster you go, the harder it is to go faster!

Going from 13.5 to 12.90 is a lot easier than, 11.5-10.90 for example.


Goodluck.

Like I say too, Nitrous makes it's own weather. haha

Inferno SRT8
04-18-2007, 01:59 PM
...inferno.... you wouldn't have picked up that much dude!

Remember the go fast rule.....

The faster you go, the harder it is to go faster!

Going from 13.5 to 12.90 is a lot easier than, 11.5-10.90 for example.


Goodluck.

Like I say too, Nitrous makes it's own weather. haha

The air that day was like nitrous it was nuts the truck was catapulting out of the gate and with the B&G Stage 2 flash on its way anything is possible right now.

I ran that 12.53 with 3/4 gas tank, tire PSI @ 32, oem Tstat and coolant temp at 205 and my intake manifold was smoking hot!!!!

Basically no truck prep at all.

GotStroke?
04-18-2007, 02:03 PM
...inferno.... you wouldn't have picked up that much dude!

Remember the go fast rule.....

The faster you go, the harder it is to go faster!

Going from 13.5 to 12.90 is a lot easier than, 11.5-10.90 for example.


Goodluck.

Like I say too, Nitrous makes it's own weather. haha


I agree but he's still talking 11s/12s. You don't really run into the issues you covered above until the 10s. I'm also of the opinion that a bone stock Jeep SRT8 w/ true aftermarket tune would run mid 12s all day long.

DavesSRT8
04-18-2007, 02:03 PM
Inferno:
Yes, I believe you would have been several tenths quicker, at least. I have not seen a vehicle so sensitive to heat soak in quite a while. I am guessing due to higher compression, the engineers are very strict at pulling timing to avoid detonation. What I am going to do is start data plotting IAT, Coolant Temp, Trans temp (to see if trans temps affect converter lockup), etc. vs 1/4 mile times and find out exactly when things start going downhill. Right now I am guessing the 'cutoff' is around 195 degrees ECT - where the computer starts pulling timing or throttle position. Since the new Dashhawk download (today) contains trans fluid temp and throttle position, gathering this data should be easy. Bottom line maybe summer = off limits for consistent runs, even with good cool downs. Had this same problem in my Lightning. No racing in the summer. May also have to switch to race gas if tuners allow timing to be adjusted (hopefully !). Not sure if the spacers will help or not, since we do not know what is being used to pull timing or reduce throttle position. (if it is, not sure how speed density maps work; i am used to a MAF and it's transfer functions)

My son (we have a black SRT8 Jeep) met you on 4/14 at Etown and those are his times I am showing (he's a very good bracket racer). He said you 2 had a couple of nice talks about the Jeep - thanks for helping him out ! Hope to see you next time in May !

Dave

Inferno SRT8
04-18-2007, 02:08 PM
Inferno:
Yes, I believe you would have been several tenths quicker, at least. I have not seen a vehicle so sensitive to heat soak in quite a while. I am guessing due to higher compression, the engineers are very strict at pulling timing to avoid detonation. What I am going to do is start data plotting IAT, Coolant Temp, Trans temp (to see if trans temps affect converter lockup), etc. vs 1/4 mile times and find out exactly when things start going downhill. Right now I am guessing the 'cutoff' is around 195 degrees ECT - where the computer starts pulling timing or throttle position. Since the new Dashhawk download (today) contains trans fluid temp and throttle position, gathering this data should be easy. Bottom line maybe summer = off limits for consistent runs, even with good cool downs. Had this same problem in my Lightning. No racing in the summer. May also have to switch to race gas if tuners allow timing to be adjusted (hopefully !). Not sure if the spacers will help or not, since we do not know what is being used to pull timing or reduce throttle position. (if it is, not sure how speed density maps work; i am used to a MAF and it's transfer functions)

My son (we have a black SRT8 Jeep) met you on 4/14 at Etown and those are his times I am showing (he's a very good bracket racer). He said you 2 had a couple of nice talks about the Jeep - thanks for helping him out ! Hope to see you next time in May !

Dave

I remember Dave nice meeting both of you, hope to see you guys again at the track soon, come to Etown for the LX event in May should be a great day! Helping out fellow SRT8 owners is what we do! Glad I could help in any way.

My GSM spacers should cut down the heat soak, they go on this weekend and should be ready for Etown in May.

generalconfusion
04-18-2007, 05:25 PM
.....congrats General!

I have a thought, when I went 12.85@104.5, I did a few of those online
dyno calculators based on that info and weighing 4920 with me in it on the line......

I kept coming up with 458ish? I assume that is flywheel estimated hp?

From what I have heard, you would lose about 15% through drivetrain etc,
prolly more with AWD....that would be over 380????????

I am thinking of this the wrong way or something?

I know a true dyno pull is different. ...believe me, you definately don't want
to run anything on a Mustang dyno. The numbers will piss you off.

I argued with a guy who swore that the Mustang dynos are the most accurate
...blah, blah, blah.....load correction, actual power....etc..etc.

I tried to tell him, if my buddy puts down "only" 750rwhp on his MustDyno, and
then goes to the track and runs 8.8@154 at 3270lbs, then something is not
right with his dyno.....it scientifically/physically takes X amount of hp & tq to
move a certain weight object a certain distance...PERIOD.

This is way off topic, I am just saying this for discussion and your thoughts.

Apologies to Timster......we kinda stole his thread but this is about heat to the SRT8 6.1 family......

Cobra keep one thing in perspective......I could have gone to XS Engineering where I know they have a DTS9000 eddie current dyno, and I have always seen "bigger"numbers......but who cares......the point here is.... did this or that mod or combination of mods at temperature make a difference. So a while back I established a baseline dyno pull and tried different combos.......before we had headers and spacers and B&G or any of these other vendors parts were around. That is good solid historical data of how the engine performs at the same dyno in the same city on the same fuel.

So with that in mind.........we want to just establish if these parts or combos work......so I now know that finally I have found the right combination of parts (for me), and that at 193 degrees my engine will pull around this horsepower.......compared to stock.

So a dyno is a tuning device and the numbers in the begining low or high dont matter......what counts is the results you see from the combination you finally end up with. Now to the track tomorrow night.

cobrakid
04-18-2007, 08:01 PM
...inferno, with what you elaborated on.....

you very well might have went 12.0s, or at least 12.teens!

The truck prep is very key to the awesome ET & big mph #s.

Goodluck, and keep us posted.

I also agree that dyno #s, and dynos themselves are merely tools for tuning
and rough measuring of hp & tq, I was just saying according to my actual
1/4 slips, I wonder what it would have dyno'd that day ????? 375-885?

Does anybody know the % of loss on the SRT8 AWD Jeeps?

Derwood98
04-18-2007, 08:04 PM
Cooler thermostat = cooler motor = cooler intake = cooler intake charge = more hp



Why would you want to make your motor run hotter? :confused:

Here's the deal. cooler motor doesn't equal cooler intake. Some motors, like my 4.0L Jeep Cherokee motor are designed to run at a certain temperature. The computer calculates timing based on engine temperature. If you get the temperature too low, the computer will try to compensate which will give you poorer milage. I honestly don't believe the cooler thermostat makes more HP unless you have mods that warrent it. There are many depends on this, but for those stock owners out there, especially those who don't race, this mod is not necessary. That's all I am trying to say.

HoustonSRT-8
04-18-2007, 10:03 PM
Here's the deal. cooler motor doesn't equal cooler intake. Some motors, like my 4.0L Jeep Cherokee motor are designed to run at a certain temperature. The computer calculates timing based on engine temperature. If you get the temperature too low, the computer will try to compensate which will give you poorer milage. I honestly don't believe the cooler thermostat makes more HP unless you have mods that warrent it. There are many depends on this, but for those stock owners out there, especially those who don't race, this mod is not necessary. That's all I am trying to say.

I understand what you mean which is exactly why I did not go with the 170° thermostat (going too low actually loses hp, we know this), but a lower than stock thermostat on these motors helps with heat soak. A cooler thermostat does not make more power, but rather frees up lost horsepower. As stated many other times in this thread, the 6.1L motor generates an extreme amount of heat and is very succeptible to heat soak which is why little mods like this make a difference. It has been proven with dynos and time slips.

As for your Jeep, Jet did not recommend adding the thermostat to make the motor run hotter. They recommended the thermostat to help your motor lose the extra heat generated by the modified fuel & timing curves that came from the module. Your stock radiator couldn't disipate the heat as fast as the lower thermostat was allowing your coolant to circulate, which is why you had to upgrade your radiator. Since you don't think it's worth it to add a mod like this to an otherwise unbuilt motor, what do you have done to your bad 4.0L? :rolleyes:

timster
04-19-2007, 05:17 AM
[QUOTE=generalconfusion]Apologies to Timster......we kinda stole his thread but this is about heat to the SRT8 6.1 family......

QUOTE]

No apologies nescessary. It's all related.

I wanted to add that in addition to lower coolant and oil temps, my average MPG is also a bit lower. I was averaging about 13.8 MPG prior to the install, and now I am averaging about 13. Another thing I've noticed since the install is my truck now consistantly hesitates durring the 1-2 shift at WOT.

HoustonSRT-8
04-19-2007, 08:36 AM
[QUOTE=generalconfusion]Apologies to Timster......we kinda stole his thread but this is about heat to the SRT8 6.1 family......

QUOTE]

No apologies nescessary. It's all related.

I wanted to add that in addition to lower coolant and oil temps, my average MPG is also a bit lower. I was averaging about 13.8 MPG prior to the install, and now I am averaging about 13. Another thing I've noticed since the install is my truck now consistantly hesitates durring the 1-2 shift at WOT.
Do you have an '06 or '07?

Hows2nd
04-19-2007, 09:51 AM
...inferno.... you wouldn't have picked up that much dude!

Remember the go fast rule.....

The faster you go, the harder it is to go faster!

Going from 13.5 to 12.90 is a lot easier than, 11.5-10.90 for example.


Goodluck.

Like I say too, Nitrous makes it's own weather. haha

You have to remember that Inferno had a day with perfect air.... I believe it was a -2800 DA, with that in mind I think with his current mods a low 12 would have happened.

timster
04-19-2007, 11:06 AM
[QUOTE=timster]
Do you have an '06 or '07?


I have a 07

:mad:

HoustonSRT-8
04-19-2007, 12:55 PM
[QUOTE=HoustonSRT-8]


I have a 07

:mad:
Then that would be related to the transmission PCM re-flash the '07s are waiting on.

timster
04-19-2007, 06:58 PM
I hardly ever get the 1-2 hesitation at wot, but since installing the tstat it happens all the time now. I noticed a similar phenomina after I replaced my stock air filter with the K&N drop in - for about 2 weeks after I added the K&N, I was experiencing the 1/2 shift hesitation like crazy...but after the third week or so it completely went away. Hope it goes away this time as well.

Anyways, I wonder if, because the truck is accellerating quicker, and because it reaches max revs quicker, the PCM/TCM's timing is off, so instead of the truck shifting smoothly like before the performance mod, it now, because of timing issues, bangs into the rev limiter. If this is the case, I wonder if the PCM can re-learn proper shift timing?

timster
04-20-2007, 09:51 PM
MPG is now getting back to where it was before (13.7-13.8)

Also, the 1-2 shift hesitation at wot isn't as frequent either. The truck hesitates still but slightly less than 50% of the time now, or 2 out of 5 tonight.

Lastly, I haven't noticed any improvement in 0-60 times, but I guess its a bit warmer up here in NewEngland now-a-days, which could account for the differences. I am averaging 4.13 - 4.15 sec now where as in 20-30 degree temps I was getting as low as 3.94 sec.

One last thing, I ran my car at idle for about 10 minutes after coming home from work...popped open the hood and felt the intake manifold...it was definitely hotter than before, but it still wasn't so hot I couldn't keep my hand on it for as long as I wanted..

EX-SVTMAN
04-21-2007, 05:36 PM
MPG is now getting back to where it was before (13.7-13.8)

Also, the 1-2 shift hesitation at wot isn't as frequent either. The truck hesitates still but slightly less than 50% of the time now, or 2 out of 5 tonight.

Lastly, I haven't noticed any improvement in 0-60 times, but I guess its a bit warmer up here in NewEngland now-a-days, which could account for the differences. I am averaging 4.13 - 4.15 sec now where as in 20-30 degree temps I was getting as low as 3.94 sec.

One last thing, I ran my car at idle for about 10 minutes after coming home from work...popped open the hood and felt the intake manifold...it was definitely hotter than before, but it still wasn't so hot I couldn't keep my hand on it for as long as I wanted..

From a guy who doesn't own one yet....GUYS!!!!! Do you realize what we have here???????? 0-60 averaging 4.13-4.15....wtf?? It's a f*cking truck......
WOW!!!! let's all step back for a second and look at what we DO HAVE....not so much at WHAT WE DON'T.
After that.... resume the thread but I think sometimes we're so occupied with the next step that we don't appreciate what we already have.
Anyways..... I admire all you guys for takin it to the next level just don't take what you have for granted....
I'm out!

Inferno SRT8
04-21-2007, 05:48 PM
From a guy who doesn't own one yet....GUYS!!!!! Do you realize what we have here???????? 0-60 averaging 4.13-4.15....wtf?? It's a f*cking truck......
WOW!!!! let's all step back for a second and look at what we DO HAVE....not so much at WHAT WE DON'T.
After that.... resume the thread but I think sometimes we're so occupied with the next step that we don't appreciate what we already have.
Anyways..... I admire all you guys for takin it to the next level just don't take what you have for granted....
I'm out!


Eheeeem my Dashhawk after Tstat install went from 4.30 to 4.03 :D

But I totally understand what your saying, were in an SUV, we live in great times gentlemen.

EX-SVTMAN
04-21-2007, 07:49 PM
Eheeeem my Dashhawk after Tstat install went from 4.30 to 4.03 :D

But I totally understand what your saying, were in an SUV, we live in great times gentlemen.

Thank you sir.
Man, I remember back when I had my LX 5.0 and I first rode in one.... I was like holy crap!!!! Those things I think did 60 in 6.2sec or something and I was amazed back then... takes me back in time man...sweet.
Now this truck runs it in about 4? Crazy but yes..."Great times Gentlemen" indeed.

timster
04-22-2007, 05:26 AM
From a guy who doesn't own one yet....GUYS!!!!! Do you realize what we have here???????? 0-60 averaging 4.13-4.15....wtf?? It's a f*cking truck......
WOW!!!! let's all step back for a second and look at what we DO HAVE....not so much at WHAT WE DON'T.
After that.... resume the thread but I think sometimes we're so occupied with the next step that we don't appreciate what we already have.
Anyways..... I admire all you guys for takin it to the next level just don't take what you have for granted....
I'm out!


heh heh

yep, the gcSRT8 is one hell of a BADA$$ truck

Blown7
03-20-2008, 04:37 PM
I'm bringin this thread back from the dead, because all the speculation as to whythe Jeep makes better power, every suggestion makes me laugh.

Everyone who posted here had ideas and they are all wrong.

(Granted this was years ago and very little about the Jeep were known as opposed to today but yet when a theromostat question is posted today on the board the same reasons as this thread are used)

Anyone care to explain why??

Hint and interal combustion engine is a heat engine and theoredically the hotter it is the more efficeient it becomes.

So why does everyone try to install a less than 203 degree stock thermostat in the quest for better performance and use heat soak as the reason?.
Less heat soak is not the core reason the Jeeps faster, neither is relocating the IAT by itself make the Jeep faster and it's not the temp of the intake that makes the Jeep faster and more powerful. I can make the same power using a stock thermostat and IAT location given the same ambient temperature so what's the difference?


J

Razorecko
03-20-2008, 05:40 PM
^ Hey B7 - How low of a temp do you think people can go before they start wearing out the cylinder walls ?

HoustonSRT-8
03-21-2008, 02:09 PM
I gave up the t-stat mod months ago.

Blown7
03-21-2008, 02:34 PM
I gave up the t-stat mod months ago.

Yep heard about that. It may possibly raise the operating pressure of the system.


On another note,

No after a full day no one has offered a answer or even a WAG on my question.........


J

DanDE
03-21-2008, 03:35 PM
Yep heard about that. It may possibly raise the operating pressure of the system.


On another note,

No after a full day no one has offered a answer or even a WAG on my question.........


J

I don't know what a "WAG" is, but I'll venture a guess on your question since no one else (most are certainly A LOT more knowledgeable than me) has chimed in. The amount of air the engine pumps through during any given part of the cycle...

Blown7
03-21-2008, 06:18 PM
I don't know what a "WAG" is, but I'll venture a guess on your question since no one else (most are certainly A LOT more knowledgeable than me) has chimed in. The amount of air the engine pumps through during any given part of the cycle...

Nope but at least your playing so I'll give a hint

200 degrees and 90 degrees.


J

BJB
03-21-2008, 06:38 PM
If I say 290 degrees, do I win something:D

Razorecko
03-21-2008, 06:49 PM
Hey B7 - if the 180 stat does nothing good for the motor than why does mopar offer a 180 tstat for the viper ?

Blown7
03-21-2008, 07:02 PM
If I say 290 degrees, do I win something:D

Nope LOL, but your too hot!

J

Car_Guy
03-21-2008, 07:03 PM
Alright, I'll play. One thing that was stated incorrectly in the beginning of this thread was: Obviously the Jeep engineers selected the components to (thermostats and relays) to achieve the best possible HP given specific conditions. As in refrigeration, we size our systems based on the worst case senarios.

Jeep enginers do not select components to achieve the best possible HP. They also have things like CAFE (gas mileage) and emissions to think about, and also things like maximum noise levels (e.g. resonators on intake and exhaust). They also have to design the vehicle to run in any climate. If you live where you see extreme cold temps., and it's like that for the majority of the year, maybe the thermostat mod is not good for you.

So first of all don't assume that just because that's how the factory engineers made it that it must be the best thing for your particular situation. Second, I don't think anyone is claiming faster 0-60 times from this mod. They are combating the all encompassing heat soak. Which can definitely be an issue for a vehicle run at WOT for more that 12 seconds. Not to mention the benefit of any cooler, more dense air charge that is going allow the computer to advance the timing. I know with the Trailblazer SS the computer starts to pull timing at any IATs above 85 degrees, I'm not sure what it is on the GCSRT8.

I have also been to many dyno wars, and before they dyno the vehicles the ice down the intakes and let the motors cools as much as possible. Is that to make less horsepower?

Blown7
03-21-2008, 07:05 PM
If I say 290 degrees, do I win something:D

Hey B7 - if the 180 stat does nothing good for the motor than why does mopar offer a 180 tstat for the viper ?

I'm not saying it's terribly bad just not optimum, as far as the Viper I am not familar with them too much althought I have purchased and disassembled a Viper PCM in an effort to run a V-10 in the Jeep.

Keep thinking why 200 and 90 are critical in the Jeep.


J

Blown7
03-21-2008, 07:06 PM
Alright, I'll play. One thing that was stated incorrectly in the beginning of this thread was:

Jeep enginers do not select components to achieve the best possible HP. They also have things like CAFE (gas mileage) and emissions to think about, and also things like maximum noise levels (e.g. resonators on intake and exhaust). They also have to design the vehicle to run in any climate. If you live where you see extreme cold temps., and it's like that for the majority of the year, maybe the thermostat mod is not good for you.

So first of all don't assume that just because that's how the factory engineers made it that it must be the best thing for your particular situation. Second, I don't think anyone is claiming faster 0-60 times from this mod. They are combating the all encompassing heat soak. Which can definitely be an issue for a vehicle run at WOT for more that 12 seconds. Not to mention the benefit of any cooler, more dense air charge that is going allow the computer to advance the timing. I know with the Trailblazer SS the computer starts to pull timing at any IATs above 85 degrees, I'm not sure what it is on the GCSRT8.

I have also been to many dyno wars, and before they dyno the vehicles the ice down the intakes and let the motors cools as much as possible. Is that to make less horsepower?

OHHHHHHHHHHHH Your Gettin Close!!!!

J

Razorecko
03-21-2008, 07:27 PM
Well at 200 we know that the pcm pulls timing - thats why we get the "strongest runs" between 160-200 - My guess on the "90" is that, - that is the time when the pcm starts monitoring the rate at which the motor warms up to proper temp. If it doesnt warm up within threshold than the cel triggers.

Inferno SRT8
03-21-2008, 07:34 PM
My best runs at the track were with the coolant at 185-190.

Jeff is making me think way to much for a friday. :)

Blown7
03-21-2008, 07:57 PM
Well at 200 we know that the pcm pulls timing - thats why we get the "strongest runs" between 160-200 - My guess on the "90" is that, - that is the time when the pcm starts monitoring the rate at which the motor warms up to proper temp. If it doesnt warm up within threshold than the cel triggers.

90 is the absolute highest IAT you want to see. In the PCM calibration timing gets pulled at two "Walls" one is the coolant temp over 200 plus additional KR
(well actually 199.something) and the other IAT

Were working on those numbers :D

But yes in lew of having the ability to adjust temps in the PCM code for now the theromostat mod works, but not because of heatsoak but because of the PCM calibration.

As a interesting sideline a 300C ran a 11 sec 1/4 in Austrailia in 100 degree plus ambient air temp yesterday.

J

Razorecko
03-21-2008, 08:05 PM
I'm actually satisfied with the way the coolant temp runs on my 08 - about 210 at 80 mph around 40degrees ambient. BUT - I'm putting in a Jet 180 because my oil temps are insane - 237 at 80mph at the above ambient & 244 at 90mph. I hit 255 last week going 100mph in 30 ambient - and this is in the winter , in the summer i'd probally turn into ghost rider on the highway. I'm using the stat more for cooling the oil than the coolant. lol but of course at the moment its back at the dealer because my transfer case is having issues. - with the trac control off at lower speeds up to 40mph i have heavy vibration going through the gas pedal and upon a slow stop - a vibration throughout the entire car. Not to mention a loud noise that sounds like a mix of whine/mesh. :D ahhh one busted gc to a new busted gc. Atleast it doesnt have an electrical gremlin -knock on wood

Blown7
03-21-2008, 08:16 PM
I'm actually satisfied with the way the coolant temp runs on my 08 - about 210 at 80 mph around 40degrees ambient. BUT - I'm putting in a Jet 180 because my oil temps are insane - 237 at 80mph at the above ambient & 244 at 90mph. I hit 255 last week going 100mph in 30 ambient - and this is in the winter , in the summer i'd probally turn into ghost rider on the highway. I'm using the stat more for cooling the oil than the coolant. lol but of course at the moment its back at the dealer because my transfer case is having issues. - with the trac control off at lower speeds up to 40mph i have heavy vibration going through the gas pedal and upon a slow stop - a vibration throughout the entire car. Not to mention a loud noise that sounds like a mix of whine/mesh. :D ahhh one busted gc to a new busted gc. Atleast it doesnt have an electrical gremlin -knock on wood

Don't quote me on this but I believe that a manufacturing defect can be found on some transfercases.

As for the Oil temperature maybe it's time for use to start looking at oil coolers installs, I wonder if the 5.7 LX Police Special oil cooler would work??

J

Razorecko
03-21-2008, 08:23 PM
^ i'll have to ask Jeff he should know for sure

Jeep Trick
03-22-2008, 06:41 PM
90 is the absolute highest IAT you want to see. In the PCM calibration timing gets pulled at two "Walls" one is the coolant temp over 200 plus additional KR
(well actually 199.something) and the other IAT

Were working on those numbers :D

But yes in lew of having the ability to adjust temps in the PCM code for now the theromostat mod works, but not because of heatsoak but because of the PCM calibration.

As a interesting sideline a 300C ran a 11 sec 1/4 in Austrailia in 100 degree plus ambient air temp yesterday.

J

So the reason you get better results with the t-stat is that you are basically tricking the PCM, not that it actually runs better cooler?

Maybe also the reason why the BWoody CAI design has yet to see a contender, part of the benefit of its design is that its lowering the IAT by bringing in cooler air and tricking the PCM.

Blown7
03-22-2008, 06:48 PM
So the reason you get better results with the t-stat is that you are basically tricking the PCM, not that it actually runs better cooler?
Correct the PCM uses the cooler temp and intake manifold temp is inconsequential

Maybe also the reason why the BWoody CAI design has yet to see a contender, part of the benefit of its design is that its lowering the IAT by bringing in cooler air and tricking the PCM.

Again that may be so, but I myself have had great success by using the stock box with a relocated IAT to the bottom of the filter box.

J

Jeep Trick
03-22-2008, 06:55 PM
Again that may be so, but I myself have had great success by using the stock box with a relocated IAT to the bottom of the filter box.

J

Pre filter? On which side?

Did you need an extention?

Blown7
03-22-2008, 07:13 PM
Pre filter? On which side?

Before the filter

Did you need an extention?

Yes I fabricated one.

J

Jeep Trick
03-22-2008, 07:41 PM
Yes I fabricated one.

J

Spliced or did you get OEM plugs and make a full fledged one???

Blown7
03-22-2008, 07:55 PM
Spliced or did you get OEM plugs and make a full fledged one???

OEM plugs, now somewhere floating around this site(do a search) there is a part number for a actual Jeep/Mopar harness extension.

I made my own as I wanted a long one (5 foot long) so I could test where the coolest location in the front of the Jeep is. (Thats a secret for now)

J

Jeep Trick
03-22-2008, 08:02 PM
(Thats a secret for now)

J

You sound like my wife!!!!

I know what you need to know but I'm not going to tell you!!!

If you knew me, you wouldn't need to know!!!! :confused:

I'm going to stick it in front of my A/C vent!!!!

Razorecko
03-23-2008, 12:17 AM
OEM plugs, now somewhere floating around this site(do a search) there is a part number for a actual Jeep/Mopar harness extension.

I made my own as I wanted a long one (5 foot long) so I could test where the coolest location in the front of the Jeep is. (Thats a secret for now)

J

:D sounds like the iat is positioned where the front scoop meets the filter box.

Blown7
03-23-2008, 04:13 AM
Another thing is how to remove the heat from the engine bay, louvers in the hood?
Side louvers in the fender?

I'm not sure.

J

SilveRT8
03-23-2008, 10:15 AM
Another thing is how to remove the heat from the engine bay, louvers in the hood?
Side louvers in the fender?

I'm not sure.

J

Jeff, my cheap way of doing this is to remove the 5ft rubber running at the base of the windshield next to the wipers.
Claude

Blown7
03-23-2008, 10:31 AM
Jeff, my cheap way of doing this is to remove the 5ft rubber running at the base of the windshield next to the wipers.
Claude

I was just looking at that yesterday wondering !

Excellent!

J

Razorecko
03-23-2008, 10:49 AM
:D when I get that damn hood i'm gonna route the front opening to run into the intake and the rear cowl will work to pull heat out of the bay. 2 for 1

SilveRT8
03-23-2008, 11:02 AM
I was just looking at that yesterday wondering !

Excellent!

J

I also replace the front one with 3 pieces 2" long each, hoping it can help the flow of air front to back. Not sure on this one but I figure it cant hurt.
Claude

HoustonSRT-8
03-24-2008, 10:57 AM
Another thing is how to remove the heat from the engine bay, louvers in the hood?
Side louvers in the fender?

I'm not sure.

J
I haven't looked at the Jeep, but the Volvo 850 guys pull the hood seal off above the firewall to allow heat release. There are no detrimental affects because the cowl panel extends underneath the hood for roughly 2-3 inches and has drains at either end to keep the weather off the engine.

My 2 cents.

HoustonSRT-8
03-24-2008, 11:00 AM
90 is the absolute highest IAT you want to see. In the PCM calibration timing gets pulled at two "Walls" one is the coolant temp over 200 plus additional KR
(well actually 199.something) and the other IAT

Were working on those numbers :D

But yes in lew of having the ability to adjust temps in the PCM code for now the theromostat mod works, but not because of heatsoak but because of the PCM calibration.

As a interesting sideline a 300C ran a 11 sec 1/4 in Austrailia in 100 degree plus ambient air temp yesterday.

J
You've confused me now. Are you advocating or disallowing the t-stat mod?

Blown7
03-24-2008, 12:37 PM
You've confused me now. Are you advocating or disallowing the t-stat mod?

Well it's kind of damned if you do, damned if you don't.

I myself am not a fan of installing the 180 thermostat, but I will do this myself to my own Jeep until we can get the temp tables eliminated in the PCM .Because if I keep the 203 degree stock thermostat in, I'll be fighting the PCM temperature maps.
What I will do is change all the "Jesus Clamp" hose clamps to a regular stainless steel worm hose clamp to make sure my hoses don't pop off like yours did.

J

HoustonSRT-8
03-24-2008, 12:45 PM
Screw stainless steel worm. Go t-bolt or go home. :p