I use my Jeep as a daily driver.
I have very very minimal mods ( CAI /180 t-stat / soon to be predator and cmr)

I purchased extended warranty and do not want to add anything that may default the warranty.

I was wondering if there is anything else I could add to increase performance.
Only thing I can find is perhaps a under drive pulley and new throttle body?

I know little to nothing about this sort of thing and was wondering if the above mentioned pieces would even have any effect on my Jeep that has such limited mods on it.

With the pulley and throttle body it would be easy enough to revert to stock if I needed to bring it to the stealership for warranty work. Only thing is , would I gain any noticeable performance for the cost of these?

Is there anything out there that would be a better bang for my buck? Keeping in mind it would have to be something that would be easy to revert to stock or not cause any issues that may void my factory warranty.

hey bro... think its a great idea.. you without a doubt will feel the improvement with these 2 mods.. just make sure you get the correct tb and nothing to big

However, im not sure if it would be that easy to keep on reverting to the oem ud pulley every time you bring her in... that may turn into a pain

hey bro... think its a great idea.. you without a doubt will feel the improvement with these 2 mods.. just make sure you get the correct tb and nothing to big

However, im not sure if it would be that easy to keep on reverting to the oem ud pulley every time you bring her in... that may turn into a pain
I agree you should feel a difference. I think the biggest you can go on the TB is 85mm w/out porting your manifold. I have an 85mm and noticed a difference and its seems to be exactly the same size as the manifold

Which TB did you decide to go with? Just doing some research on them now. Like I said before it would have ot be something that is minimal work to revert to stock if for some reason I had to take it in for warranty work.

In my opinion the underdrive pulley and TB will definitely void your wattanty and they wont help that much if any. On a stock 6.1 stay with the stock TB as its enought to handel your needs and theres a lot of guys that get idling problems with both 85 & 90 TB. The 1 who knows best on the TB is SARGE as he has tried them on his 6.1 i think. I dont have either of them and i do very well at the track with my times. Maybe someone who has tried both at the track can chime in.

The basic's:

If you underdrive, you're going to loose some electrical charge capacity. Estimate your needs by what is in your particular jeep. I have the aftermarket Navi and twin tv's along with all the bs in the plugs for mp3 players and phone, then add your lighting system and figure a load amount. Now assume you're going to drop that by something like 15%. I did underdrive on my mustang, they came right back off after cooling and charging issues and became rather expensive paper weights.

Oversized TB. Again, basics here, you could have a 200mmTB and it wouldn't make a difference without other modifications. An engine is nothing more than a giant air pump, and only so much can get in and out without forced induction. (or alot of head work)

Bottom line here, for what the TB alone cost its a waste of money. I forget what they cost (when i looked i think i **** myself) but you aren't gonna gain more than 1-2hp if that, so the hp to $$ ratio is very poor.

I'd personally, if I felt that I need more HP which I don't as no one ever leaves me behind, get one of those bbill valve bodies for trans improvement. I'm not even doin that since this srt is my wifes DD but the learning curve has taught me over the years that certain mods should be done long before others.

Just my 2 cent

There are others on here who run LOW 11`s with the stock TB....

I run a stock TB, and I have a ported intake.

But im not trying to say you get no performance improvements with a bigger throttlebody... I just dont think it will do much, definitely not enough for you to "feel" a difference in HP.
Maybe... If you had a stroker motor... and you port/polish the manifold + add a matching TB you might pick up a few horses. With so few mods on the stock motor I dont see you getting much power from that mod.

The underdrive pulley will help you alot more than a TB.

Oversized TB. Again, basics here, you could have a 200mmTB and it wouldn't make a difference without other modifications. An engine is nothing more than a giant air pump, and only so much can get in and out without forced induction. (or alot of head work)

Bottom line here, for what the TB alone cost its a waste of money. I forget what they cost (when i looked i think i **** myself) but you aren't gonna gain more than 1-2hp if that, so the hp to $$ ratio is very poor.


^ I agree with this guy ^^

Well put imo

I've been told that without headers, increasing TB size is pointless in terms of $$-to-HP ratio. We've often heard that the restriction is in the headers not the intake side of the motor right? That's the reason the Jeep is 420hp and the other SRTs are 425hp.

Also I think it would be more cost efficient to have your TB ported (seen prices as low as $100 for this). There's a thread on LXF that talks about the intake manifold being 85mm already (there's a rubber gasket to ensure proper fit for the 80mm), so no need to port out the intake manifold for an 85mm TB.

just my $0.02 :)

I've been told that without headers, increasing TB size is pointless in terms of $$-to-HP ratio. We've often heard that the restriction is in the headers not the intake side of the motor right? That's the reason the Jeep is 420hp and the other SRTs are 425hp.

Also I think it would be more cost efficient to have your TB ported (seen prices as low as $100 for this). There's a thread on LXF that talks about the intake manifold being 85mm already (there's a rubber gasket to ensure proper fit for the 80mm), so no need to port out the intake manifold for an 85mm TB.

just my $0.02 :)

Don't know the spec's of the stock headers offhand, but I'd imagine they are relatively large. I mean, back in the day a set of 1 7/8 headers were enormous and extremely expensive. Typically, a "truck" vs a "car" with the same motor, there will be a smidge less hp and a smidge more torque, most of the time due to a change in the intake manifold. I'm not well versed in chrysler products so I don't know if this holds to be true in this application or not. (ie I know the ford truck and mustang use the same 4.6 but the truck has a torque based intake vs a hp based on on the stang)

As for porting, I don't see the benefit. Consider this: You have a hole, which is stopped up with a plate. When you depress the throttle, the plate opens, and when you release it closes. If you increase the diameter of the tube that comes to the plate without increasing the diameter around the plate, you really haven't accomplished much (and I know cause I ported one on my last car, hours of work for nothing honestly) The same amount of air still goes through the circumference of the plate when open as before ported. Is there a benefit, sure maybe you get another .001 cubic inches of air. Is .001 worth the time and effort of porting, or parting with $100? Unless your running blown, simply put no.

But this is a hobby, sport, pastime even and people will try new things everyday, some of which will prosper and some of which will fail. I've tried most of the basic mods and bolt ons through the years, and i've never seen one that truely met its claims. (aka 10-15hp from a tb spacer.......maybe if its full of nos when installed) Most claims of gains are greatly inflated from cars with other mods and OPTIMAL conditions during testing. But to each his own;)

Who makes them and what is a good price?

I'm interested in the under drive pulley. Where can I get one and are the cons? I know you lose a bit of charging power but is that a problem?

Bob

do you HAVE a 180thermo and no predator? (stock fan settings?)

if so this is the first thing you need to solve...

do you HAVE a 180thermo and no predator? (stock fan settings?)

if so this is the first thing you need to solve...

Yes I have the 180 Jet Stat and the predator fan tune. I had a underdrive pulley on my SC Pontiac but I wanted to learn what others have experienced in the SRT8.:)

I use my Jeep as a daily driver.
I have very very minimal mods ( CAI /180 t-stat / soon to be predator and cmr)

no re-read the first post...

i wouldnt do anything until you got the predator and help out that t-stat

Here's a link for more info-

http://www.cherokeesrt8.com/forums/showthread.php?t=16983

Bob

I would say is a waist of money if you're not going to do crazy mods . A good tune CAI should yield you same numbers . Look at my numbers , no pulley no TB . All i have is a Tune , CAI , 180 Tstat , Borla S !!!

A good tune CAI should yield you same numbers . Look at my numbers , no pulley no TB . All i have is a Tune , CAI , 180 Tstat , Borla S !!!

and a 600 DA :)

and a 600 DA :)
HAHAHAHHAHA The 598 DA Corrects my PB To :
Stock and Mildly Modified Naturally Aspirated Engines
12.509 @ 107.468 MPH
At 600 would be The Same :D

HAHAHAHHAHA The 598 DA Corrects my PB To :
Stock and Mildly Modified Naturally Aspirated Engines
12.509 @ 107.468 MPH
At 600 would be The Same :D

yeah it dropped your PB .04 or whatever... now imagine if you were in 2000da :)

its all good just bustin your balls

yeah it dropped your PB .04 or whatever... now imagine if you were in 2000da :)

its all good just bustin your balls

My stupid light just came on!:o What are you talking about? Inside humor?:confused:

do you HAVE a 180thermo and no predator? (stock fan settings?)

if so this is the first thing you need to solve...

Yes I have the 180 Jet Stat and the predator fan tune. I had a underdrive pulley on my SC Pontiac but I wanted to learn what others have experienced in the SRT8.:)

no re-read the first post...

i wouldnt do anything until you got the predator and help out that t-stat

I would say is a waist of money if you're not going to do crazy mods . A good tune CAI should yield you same numbers . Look at my numbers , no pulley no TB . All i have is a Tune , CAI , 180 Tstat , Borla S !!!

and a 600 DA :)

HAHAHAHHAHA The 598 DA Corrects my PB To :
Stock and Mildly Modified Naturally Aspirated Engines
12.509 @ 107.468 MPH
At 600 would be The Same :D

yeah it dropped your PB .04 or whatever... now imagine if you were in 2000da :)

its all good just bustin your balls

i think you missed the whole last page... :)

yeah it dropped your PB .04 or whatever... now imagine if you were in 2000da :)

its all good just bustin your balls

I know man all in good humor here ;)

There are others on here who run LOW 11`s with the stock TB....

I run a stock TB, and I have a ported intake.

But im not trying to say you get no performance improvements with a bigger throttlebody... I just dont think it will do much, definitely not enough for you to "feel" a difference in HP.
Maybe... If you had a stroker motor... and you port/polish the manifold + add a matching TB you might pick up a few horses. With so few mods on the stock motor I dont see you getting much power from that mod.

The underdrive pulley will help you alot more than a TB.

^ I agree with this guy ^^

Well put imo

VERRY true, TB has minimal gains for the money they are for a stock motor. UD pulley would be a better choice but make sure you understand the concept of a under drive pulley all your accessories on your engine are being under driven to rob less power from the engine. imo not a good idea for a DD if you like to use your a/c a lot or if you plan on upgraded speakers/sub/etc. just my 2cents.

Throw in a nice cam and get it tuned, it will make a big difference and the dealership wont be able to tell....unless you go with an aggressive cam and some serious lope.

Throw in a nice cam and get it tuned, it will make a big difference and the dealership wont be able to tell....unless you go with an aggressive cam and some serious lope.

Man, that's major work!! I'm not up to installing a new cam:eek:

Man, that's major work!! I'm not up to installing a new cam:eek:
No argument there...there is a degree of difficulty difference between a cam install and a TB or UDP but for money spent I think it is going to yield the highest net gain.
Otherwise, like mentioned before do an upgraded valvebody and tune.

Don't know the spec's of the stock headers offhand, but I'd imagine they are relatively large. I mean, back in the day a set of 1 7/8 headers were enormous and extremely expensive. Typically, a "truck" vs a "car" with the same motor, there will be a smidge less hp and a smidge more torque, most of the time due to a change in the intake manifold. I'm not well versed in chrysler products so I don't know if this holds to be true in this application or not. (ie I know the ford truck and mustang use the same 4.6 but the truck has a torque based intake vs a hp based on on the stang)

As for porting, I don't see the benefit. Consider this: You have a hole, which is stopped up with a plate. When you depress the throttle, the plate opens, and when you release it closes. If you increase the diameter of the tube that comes to the plate without increasing the diameter around the plate, you really haven't accomplished much (and I know cause I ported one on my last car, hours of work for nothing honestly) The same amount of air still goes through the circumference of the plate when open as before ported. Is there a benefit, sure maybe you get another .001 cubic inches of air. Is .001 worth the time and effort of porting, or parting with $100? Unless your running blown, simply put no.

But this is a hobby, sport, pastime even and people will try new things everyday, some of which will prosper and some of which will fail. I've tried most of the basic mods and bolt ons through the years, and i've never seen one that truely met its claims. (aka 10-15hp from a tb spacer.......maybe if its full of nos when installed) Most claims of gains are greatly inflated from cars with other mods and OPTIMAL conditions during testing. But to each his own;)

The stock exhaust MANIFOLDS are different on the Jeep's vs. the LX's. There is a 5hp decrease in our motors b/c of the design of the manifolds. They had to "shoehorn" the motor in the Jeep and couldn't use the same manifolds from the LX's. That created the 5hp. loss in our rides. The 6.1L is the same in all Mopar vehicles. There is no difference with the exception of air boxes being on different sides.

To the OP.... I've got both the 85MM Fastman TB and a 17%(IIRC) UDP. I noticed a fractional gain at the track with them. It was like .1-.15 if that. The thing I did notice immediately with the TB was the throttle response. It was improved greatly. I'm running 12.3's and will go lower the next few times at the track depending on weather. Haven't been back to the track with my new tuning changes yet. All in all.... I like the 2 mods I did. You'll benefit more from a good CMR than these 2 mods for sure. Your times will be much lower for about the same money.

The stock exhaust MANIFOLDS are different on the Jeep's vs. the LX's. There is a 5hp decrease in our motors b/c of the design of the manifolds. They had to "shoehorn" the motor in the Jeep and couldn't use the same manifolds from the LX's. That created the 5hp. loss in our rides. The 6.1L is the same in all Mopar vehicles. There is no difference with the exception of air boxes being on different sides.



I was told at some point that the intake manifold is taller on the jeep as well...to make more torque... .is this false??

It looks taller to me compared to other srt's. maybe its just in my head :o

False..... they're all the same. Motor sets higher in our rides. Maybe that's it. You see any aftermarket Intake Mannys that specify for Jeeps or LX's? Nope, cause they're all the same.

One other difference in the 6.1 Jeep vs. 6.1 LX is the oil pan and pick up tube.

One other difference in the 6.1 Jeep vs. 6.1 LX is the oil pan and pick up tube.

I stand corrected...... thanks dude.:D I was really referring to the main portion of the engine. Those are a minor details. :lol:;)

Just bump idle rpm's with your tuner. +150 across the board worked perfect, didn't effect drivability at all and idling with accessories cranked, a/c, lights, everything, I get 14v and up. I tried +200rpm, it just starts to effect shift in/out of gear, and you can just start to feel some very slight push when waiting at a light in D, +150rpm worked perfect for me. To add, I'm sure I gained back all my coolant pump flow down low too, good to have on the hot days.

Just my two pennies: I've got a Fastman 85mm throttle body and I noticed a difference with it (and a tune), mainly in throttle response, maybe shaved a tenth. It has a half-shaft and a tapered bore, tie it together with a decent tune and I think it's a solid investment. There are a couple other guys that could chime in on the product, Kelly, Harrison? ...if they didn't already...I didn't read through the whole thread...if so, sorry! :worried:

Read 6 posts above yours bro. Haha.

False..... they're all the same. Motor sets higher in our rides. Maybe that's it. You see any aftermarket Intake Mannys that specify for Jeeps or LX's? Nope, cause they're all the same.



cool.....thanks for clearing that up Harrison :D I thought that sounded a lil fishy...but I never looked into it obviously:o

I stand corrected...... thanks dude.:D I was really referring to the main portion of the engine. Those are a minor details. :lol:;)

Haha, its all good HarryB...I only realized this when the dealership got my replacement motor in and had to use my exisiting oil pan.

Read 6 posts above yours bro. Haha.

Damn...and it was almost a carbon copy of your comments. :ack:

Damn...and it was almost a carbon copy of your comments. :ack:

HAHA.... great inds think alike. Well, at least the OP has 2 opinions about the same product that are about the same when the second didn't even read the frist one!:rofl:

Right! Yeah, yeah! That's it! I'll roll with that one!

From the mods I just had down. I'm not seeing/feeling any power loss. I don't see them in my HIDS or hear in my subs. I do feel the HP gains like crazy. It's all in what you want to put into it. By the way, mine is a DD in the nice weather months.

Roll Out!!