Get a inter-cooler.. that will really take care of your KR

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Why have more money than brains? Cuz RACE CAR

Get a turbo. That will take car of your slow. Jk. You're GT is super ballin' after the all that work you just put into it.

-- Tue Aug 24, 2010 5:37 pm --


Well there's your problem.
Seriously though, headers would help also.

Those TR6's should help a little too since they are colder than stock.

Also found this on ZZP's site.

04-05 GTP or Comp G & 06 GT supercharged

3.8 pulley totally stock car

3.6 pulley Colder Tstat & spark plugs, downpipe, Cold air intake (still could have KR)


So according to them, even with different plugs and a downpipe (both of which you don't have right now and are still running a 3.6 pulley), you still could have some KR though that ZZP pcm might take care of it if you take car of the DP and plugs.

Smaller pulley = more air into engine, but nothing has been changed yet to let that additional air out of the engine.

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Dubs:00 VW GTI VR6, Low and Slow; 91 VW GTI 8v, Restoration Project; 91 VW Cabriolet 8v, bitch Basket
GP's:04 GP GT, Past now G-Ma's; Ex-Girlfriend's 97 GP GT, "Project Pink Power"

actually i forgot to mention i do have a dynomax cat back system on. you can tell by the backpressure that the flow has increased but i doubt a cat back would make too much of a difference. I think i'm just going to order a 3" catless DP with the money i'll get back from the pulley puller and pcm core charge. I'm wondering how much of a difference a throttle body spacer will make. and without a scanner i'm not sure if it's KR or belt slippage. at high boost the engine seems to cut out including the supercharger whine, obviously. i'm using a belt that's supposed to be for pulleys up to 3.5" but it fit on with the 3.6" without the tensioner pulley being fully extended so i think it should be fine. as far as an intercooler goes that'll probably be next spring when i get my bonus... can't afford it now.

-- Wed Aug 25, 2010 7:45 pm --

headers will most likely be next spring as well since the TOG headers i want run $749.99

-- Wed Aug 25, 2010 7:53 pm --

i'm gonna do wires when i do the plugs tomorrow too.

Headers will eliminate alot for your KR. The factory manifolds are extremely restrictive, then after headers I suggest a retune.

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you think headers will eliminate more KR than a 3" catless downpipe? and what about running a 160 degree thermostat? i had some douchebag in a camaro try to race me yesterday but i couldn't because i know i can only go like 3/4 throttle because of the KR. headers would be nice but i just don't have the cash right now.

Headers PLUS the DP (most headers require their own special DP) will do the most.

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Although gold dust is precious, when it gets in your eyes, it obstructs your vision.

Most headers com with a downpipe. I wouldn't suggest running anything lower than a 180 degree t-stat, especially on an 04+. A 180 is the coldest stat is recommended for the 04+. Using a 160, the PCM commands too rich of a fuel mixture, or an engine code can be set.

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On a N/A car how what headers are good and some one told me the back preasure caused by the stock exaust is actually good. Sry to thread jack just figured i piggyback here instead of making a new thread.

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All sho no go...

Technically, backpressure on any car is bad for any engine, but the terminology of the word backpressure is misleading since it's really the flow rate of the exhaust gases that matter and "backpressure" would mean that the gases are flowing backward into the engine from the manifold, when in reality when people mention backpressure on an N/A car it's just that exhaust is flowing at a rate that does not exceed the maximum exhaust flow output of the engine as a spefic rpm. It is correct that N/A cars need "backpressure" to create low end power, hence why headers aren't always the best first step in modding an N/A car. You could get a power log front manifold and that would help out a little without making the car's torque curve fall on it's face. Also, this is why running open headers or a cutout on an N/A car isn't always helpful. Granted with decreasing backpressure on any type of engine frees up some high rpm power, but usually it's quite neglegable on an none boosted car. Not to bring my Dub, an N/A car, up for the millionth time, but it's current straight piped right now (wasn't my choice. Nature took it toll on the exhaust welds) and my low end torque has gone down considerable and that still with 5 feet of the stock (2.25 inch pipe and Cat). If it was complete open header the torque would go down even further.

Now time to confuse the heck out of everyone.
From http://forums.beyond.ca/showthread/t-265490.html :
texasnick
Backpressure being a good thing is a retarded myth, and overused by ricers IMO. It's all about the flow rate of exhaust gas out of the motor not being hindered by the exhaust.

Remember fluid mechanics;

Q = v*A

where Q = Fluid Flow Rate
v = Fluid Velocity
A = Cross Sectional Area of what the fluid is flowing inside of.

Q will have a maximum value at a specific RPM. If your exhaust is too restrictive, it will not allow for this maximum Q. You will only get, say 95% of the maximum. You can increase the diameter of the exhaust piping to help achieve this maximum Q out of the exhaust, but past the point where you actually reach this maximum you will experience less performance.

Why?

You have reached Qmax. The motor is incapable of achieving a higher flow of exhaust gases out of it. Therefore, Q becomes constant. Now, what happens when you have a constant Q and you increase A? v decreases.

As far as pressure goes, the higher the velocity of air coming out of the engine is, the lower pressure is exerted back onto the engine, ie backpressure. The trick is to maintain this Qmax while having the highest v possible, reducing or eliminating back pressure.

Basically, you put an exhaust that is too big (in Diameter) on your car and the exhaust flow coming out of the motor isn't high enough to warrant it. Exhaust velocity decreases and puts MORE pressure back onto the motor.


The only thing length has to do with these, is frictional losses of the fluid and possibly the ambient temperature of the air around the exhaust tip.

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Dubs:00 VW GTI VR6, Low and Slow; 91 VW GTI 8v, Restoration Project; 91 VW Cabriolet 8v, bitch Basket
GP's:04 GP GT, Past now G-Ma's; Ex-Girlfriend's 97 GP GT, "Project Pink Power"

I put my car back to stock other than the TR6s, 180 Stat, Bosch Wires, and ZZP computer and it's still doing it... ZZP says they think I chipped a piston. Car idles fine when cold, can get up to 4k RPM when at part throttle but when the throttle's pushed past about half way it starts cutting out... misses at idle when warm... tried using a bore scope from a local shop but I couldn't see shit, it was well used... might just buy one. Might just buy a shitty car for winter and overhaul everything next spring too. Anyone have any ideas or thoughts?

-- Fri Sep 24, 2010 11:54 am --

oh and absolutely no DTCs or check engine light

How much knock were you seeing? If you run a car with a "significant amount of KR" then you take the chance of chipping a piston. How long did you run it with the knock?

Did you change out your plugs for fresh ones and what do you have them gapped at?

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04 GTT - Retired
Best ET 13.016
Best Trap 115.56 MPH

i had the stock plugs in when it started and switched to TR6s gapped at .055" shortly after. not sure what i had for knock because i dont have a scanner but the check engine light never came on and i couldn't hear any knock. Not sure if it's harder to hear on this engine or not but I had 95 4.6 litre crown vic and if u didn't use high octane gas it'd knock so I do know what it sounds like. I ran it for a half hour before it started running shitty. I let it warm up and did one 0-90mph and a 60-90 obviously with some time for cool down in between. I drove to UPS shipped back the stock PCM and Pulley Puller then on the way back it started skipping.

You need to figure out how much knock you have. I recommend a Aeroforce gauge.

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04 GTT - Retired
Best ET 13.016
Best Trap 115.56 MPH

The way I found out I chipped a piston, (both times) I removed the sparkplug from the motor and the gaps was closed due to the metal chunks making contact with the sparkplug. If you see this; you got problems

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