Breaking 13 seconds - Cherokee SRT8 Forum
WK1 General Performance Discussion If you are planning on modifying your Jeep Grand Cherokee SRT8 with a performance enhancing modification, this is the section to post about it.

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post #1 of 29 (permalink) Old 05-19-2007, 01:01 AM Thread Starter
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Question Breaking 13 seconds

Now that I've been to the track I know I'm 13.1 to 13.2 sec in the 1/4. Is it possible to break 13 sec with bolt-ons? My next move will be exhaust and intake. Could this be enough to do it or will I need to do more? Just currious.
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post #2 of 29 (permalink) Old 05-19-2007, 01:41 AM
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Several (at least a handful) have gone 12.8-12.9@104-105 with just a T-stat and/or fan mod and good air.
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post #3 of 29 (permalink) Old 05-19-2007, 01:46 AM Thread Starter
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Quote:
Originally Posted by GotStroke?
Several (at least a handful) have gone 12.8-12.9@104-105 with just a T-stat and/or fan mod and good air.
So it sounds like the mods I mentioned should do the trick. Hasn't SRT engineering advised against the cooler T-stat claiming they designed the Jeep to run hot. I read something about that in another thread that SRT responded to. I also believe that SRT claimed they had not actually tested the lower T-stat.
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post #4 of 29 (permalink) Old 05-19-2007, 02:20 AM
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Quote:
Originally Posted by FastJeepSRT8
So it sounds like the mods I mentioned should do the trick. Hasn't SRT engineering advised against the cooler T-stat claiming they designed the Jeep to run hot. I read something about that in another thread that SRT responded to. I also believe that SRT claimed they had not actually tested the lower T-stat.

The best advice I can give you is to ignore what the SRT engineers say. They're on a short leash so to speak; imagine the potential warranty/liability/emissions implications.
More members than I can count have successfully used a cooler T-stat (MotoRad/Valucraft 383-170 or 383-180 (176*-180)) and found power. We're talking about a solid 2 tenths in the quarter when combined with the also dirt cheap fan mod.
Those same engineers also state that the full factory exhaust is optimal. Etc, etc. etc.

Last edited by GotStroke?; 05-19-2007 at 02:29 AM.
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post #5 of 29 (permalink) Old 05-19-2007, 04:39 AM
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Quote:
Originally Posted by GotStroke?
More members than I can count have successfully used a cooler T-stat (MotoRad/Valucraft 383-170 or 383-180 (176*-180)) and found power. We're talking about a solid 2 tenths in the quarter when combined with the also dirt cheap fan mod.
Count me as one of those that went from 13.2 to 12.85 for almost no money. 170* when used above 60* ambient will not throw a code either. This does NOT mean that your JGC will be at 170* while driving....it still reaches 200* range.

Can't believe with this being posted dozens upon dozens of times guys would hesitate to do a simple mod that may take an hour or so for the fan mod (see FAST writeup) and the thermostat change.

The next mods get more expensive,,,Dana 60, supercharged 426 low compression engine, user programmable electronics etc.
Bill
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post #6 of 29 (permalink) Old 05-19-2007, 04:40 AM
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do the stat it works, its cheap to do and the thing does run cooler!!
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post #7 of 29 (permalink) Old 05-19-2007, 04:54 AM
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My personal experiences so far (at just 700 miles)

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 installed and 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.

Total cost:
$11.99 for Autozone thermostat (Valuecraft)
Already had wire/switch for fan mode = $0.00

TOTAL: $11.99 to pick up 3/10's in 1/4. With more practice on the 60 foot (the 'normal' rule = 1/10 in 60' = 2/10 in 1/4) I believe this is a 12 second Jeep. In fact, Dashhawk is showing better times now that I've found the sweet spot for the powerbrake - 1800 RPM = 3.93 sec 0-60, consistently. Can't wait to get back to track and try again.

Love this thing.

Dave
2007 GCSRT8

Last edited by DavesSRT8; 05-19-2007 at 05:00 AM.
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post #8 of 29 (permalink) Old 05-19-2007, 07:46 AM
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Use my link below for the Fan Mod. It will help a ton. This motor is extremely prone to Heat Soak. We ran water on the intake for 20mins and let it cool down for 45min. I gained 1.2 sec. If I had the fan mod at the time I would have been in the 12.s for sure. Also Ice it down if you can. Two bags of ice on the intake will help.

I also believe these motors are slightly starved for air from the factory. The CAI and the exhaust will help it breath much better. OH and move your ITA into the intake box to lower its readings!

Good Luck

FASTmade Ediff & TCM switches, 170 Stant, B&B Catback, Dynamic Heads, FRE Hellfire Cam, Kooks LT's
ARIZONA SPEED & MARINE Vortech SuperCharger Kit, ASM Phenolic Spacers, UniChip,
B&G StageII, UniChip, Kenne Bell Boost a Pump, Walsh Racing Heat Exchanger.

MOD DIRECIONS
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post #9 of 29 (permalink) Old 05-19-2007, 09:02 AM
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Quote:
Originally Posted by BuilderBill
Count me as one of those that went from 13.2 to 12.85 for almost no money. 170* when used above 60* ambient will not throw a code either. This does NOT mean that your JGC will be at 170* while driving....it still reaches 200* range.

Can't believe with this being posted dozens upon dozens of times guys would hesitate to do a simple mod that may take an hour or so for the fan mod (see FAST writeup) and the thermostat change.

The next mods get more expensive,,,Dana 60, supercharged 426 low compression engine, user programmable electronics etc.
Bill
Question: What temps do the motors get without the t-stat mod? I think the usual rule of thumb is that motors usually make their most available power at just about 200*. Does the stock setup go beyond that? Or do these Hemis make more power @ 170-180ish*?

Also I think you guys would have a lot to benefit from spraying meth/water into the intake stream... and make the ice on the intake a thing of the past.

2002 EXPLORER
Blown 304 Big Bore by Modular Performance, Fox Lake Stage II heads, small m90 SC, 60lbs injectors, 2400MAF, ported intake, meth injection, custom CAI, JBA headers, true dual 2.5'' exhaust, X pipe, flowmaster super 40's and many more mods... Part-Time 4wd.
http://modularperformance.com/customers.html

Exhaust Clip
http://media.putfile.com/AWDROCKS-H-Pipe-88

FUTURE MODS
Rebuild entire drivetrain & AED 2300ax SC, NOS, Roll cage
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post #10 of 29 (permalink) Old 05-19-2007, 09:43 AM
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Is this setup simular to the ESP FAN MOD by GSM? I purchased one a few months back and decided not to install due to warranty concerns. Now I am having second thoughts.

My best time w/o it is 13.03 at 101.60 w/ a 1.78 60ft

K
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