what to do first

L

LeathalBoost6

New Member
Joined
May 5, 2004
I just bought a Auto Tap scan tool and now i am ready to get aftermarket parts ,but the question is what to do first .Now i have been doing some research and from what i am seeing and what i am hearing is that the stock PCM really hurts the performace on the GTP ,so i was thinking about looking for a aftermarkt PCM then go for the intake ,pulley,and exhaust but i just wanted some input from other people on what is the thing to do.
 
It is VERY IMPORTANT that you scan for KR (knock, detonation).very important. this is where you can make or break an engine.

the factory PCM is not the way to go if you want to make HP on this car. if you are going to get a PCM go with the DHP. the factory PCM run the engine too HOT (210-215 degree) heat is the number cause of KR. this pcm is not like the old school ECM. if you make a modification to the engine the pcm might want to know about it. this kind of modding mentalty will seek you the high HP.

before i can make any other recommendation i must ask this question. HOW MUCH HP DO YOU WANT TO MAKE?, are you look to take this car to the track? or are you just going to street race it?who fast do you want to go? when you can answer these question you will spend less money getting there. if you don`t know that answer to thse question you will just be guessing and find your self buying mod`s that you will soon be selling to upgrade to other mod`s. STAY AWAY FOR STAGE PRODUCTS. if you are going to spend you money, be asure you are buying the best and not something you have to up grade too later on

i will say at your current level you will want to look at Timing, KR, O2 mv(milivolts) (important data) . your first place for improvement should be the exhaust system. if you plan on make more that 300Hp@ the wheel get a set of TOG headers. remove the U-bend.

here is an example:

3" pulley
custom tune DHP
TOG header
Cam
ported heads =308+HP the same application with an intercooler and professional tuning 420+HP@ the wheel.

i am currently test a cam/valvetrain to make 400HP NON-intercooler. now when you start making this kind of hp you will have to address the transmission.
 
Well the car is a my normal day to day driver. So really im just set on tryin to hit low 13s . I have been watchin the knock but the highest was 2.4 from a launch . I am new with these cars but from what i am seeing i am not sure of is that when the computer sees knock the waste gate or pressure release on the supercharger opens and releases the pressure and recycles through the supercharger so to keep the motor from blowing or getting to much knock.I just wasnt sure if the stock PCM hurts the performance on the modds like a 3.4 pulley because of it making more boost the knock probably will go up so i was thinking maybe it will just dump the extra boost the pulley makes.
 
To run the 3.4 with out any KR you will need:

CAI

U-Bend Delete

Cat-Back Exhaust

180 T-Stat

The PCM isnt needed to run the 3.4, but if your shooting for the high 13s I would say its a must.
 
Is the 3.4 the pulley to go with because i seen a 3.25 pulley but someone told me that i dont have enough mods for the 3.25. I also went to intense racing and found the ls1 TB for the gtp but didnt see any regular TB that are just bored over a little as a matter of fact i havent really seen anyone with a different TB
 
I know of a person who has hit the low 13's on the stock PCM. HOWEVER, he was using bigger than stock injectors and had to reset his PCM after every run otherwise the PCM would relearn the fuel tables for the bigger injectors and then would run too lean down the track. I know of more who have run high 13's on the stock PCM no issues.

My suggestion (and order) for mods would be this:

1) free flowing exhaust (*most important)
--- delete the U-bend and the factory downpipe manifold flex joint, upgrade the tubing to 2.5" mandrel bent tubing (at the very least) and install a free-flowing muffler. I recommend 3" exhaust but it will be louder.

2) free flowing induction
--- delete the factory airbox. I have noticed the L67's like 3.5" or bigger induction tubing. route your induction tubing to outside of the engine compartment and put a K&N cone filter there. try to keep all your bends large radius if possible.

3) bigger or less restrictive TB
--- pre 99? throttle bodies had an aluminum ridge cast into them for the MAF sensor. 99?-up models did not have this ridge which made them flow a little better. You could also remove the screen to increase flow a little. Some people have had mixed results in doing this but it is a free mod and is reversable if it doesn't work for you. I have also heard you can port the TB a little for modest flow gains. You could also upgrade to the LS1 TB but I don't think that is necessary for a 13 sec car.

4) Smaller SC pulley. (size depends on overall mods)

Here is where it gets fuzzy. There are a lot of different directions you could take at this point. Personally, I would port the heads first, then worry about installing a cam or rockers and get the PCM upgraded later. No doubt if you do anything after step 4 you are probably going to need a PCM reprogram to make the engine run correctly. But, doing everything up to and including step 4 should get you into the low 14's/ high 13's depending on the car and your driving ability.

There are different performance recipies out there and everyone seems to have a different opinion. But based on my professional training and experience with forced induction engines, the most important thing is to make sure you can get the air out of the engine. A restriction in the exhaust system can cause what is known as "boost stacking". This means that excessive backpressure (restriction) in the exhaust system will cause cylinder pressures to go high resulting in detonation.

Another thing to be aware of is the stock L67 comes with very tight top piston ring end gaps. This means that if you try running too much boost or get a lot of detonation you run the risk of breaking off the top of the piston at the ring land due to the butting together of the ring ends. Besides that the stock pistons are only hypereutectic casting which means they won't survive long under detonation anyway. My advice would be to buy a stand alone knock gauge kit from caspers and install that so you can keep an eye on the knock.
 
Oh yea a 180 stat wouldn't hurt and you could hot-wire the cooling fan(s) so the engine will run cooler. Some people swear by the 160 stat but I will tell you why you should not run one:

Several components in the engine depend on oil splash for lubrication. Furthermore, some components, like the pistons, rely on a certain operating temperature so they expand to the proper size for maximum effecientcy. If you run a 160 stat, there is a good chance the oil will not reach operating temp which means it will not lubricate piston walls and other components properly. Also, the pistons may not expand completely which means the rings will have to work harder resulting in accelerated cylinder wear. Now most people will argue this point but I have seen the test results to prove it. I have also witnessed real-world proof that it is a definate possibility. Its up to you, but is a couple of HP really worth wearing out your engine prematurely?
 
Originally posted by Darth Fiero
Oh yea a 180 stat wouldn't hurt and you could hot-wire the cooling fan(s) so the engine will run cooler. Some people swear by the 160 stat but I will tell you why you should not run one:

Several components in the engine depend on oil splash for lubrication. Furthermore, some components, like the pistons, rely on a certain operating temperature so they expand to the proper size for maximum effecientcy. If you run a 160 stat, there is a good chance the oil will not reach operating temp which means it will not lubricate piston walls and other components properly. Also, the pistons may not expand completely which means the rings will have to work harder resulting in accelerated cylinder wear. Now most people will argue this point but I have seen the test results to prove it. I have also witnessed real-world proof that it is a definate possibility. Its up to you, but is a couple of HP really worth wearing out your engine prematurely?
Click to expand...


this is not intend has a flame. but after rebuild over 200 engine in our speed shop. i have never hear of suck of think. if someone is concern about the above topic. i am sure they can run a lighter weight oil like mobil1 syn 5w-30. i will consider the odds here. Heat is the number cause of KR. keeping the combustion chamber temp down will help prevent KR. you have to understand when the air/fuel mixture is ignite. the combustion temp can range from 650-850 degree.

here is a picture of what a normal combustion and detonation looks like in the combustion chamber.

http://f2.pg.photos.yahoo.com/ph/stevexperformance/detail?.dir=/e15c&.dnm=a688.jpg

now you can run the engine cooler and get 200,000+ miles

or

you can ignore engine temp and KR cause this

http://www.gfwcperformance.com/image/pcm/pic5.jpg
http://www.gfwcperformance.com/image/pcm/pic4.jpg
http://www.gfwcperformance.com/image/pcm/pic6.jpg
this piston was remove from a bone stock 2000 GTP. something like this can cost you thousand $$$$. is the couple of HP worth a damage motor do to excessive heat in the combustion chamber because the coolant has a poor ability to absorb heat?


but you don`t have to take my work for it, just ask some of the professional engine builder.
 
I don't take that as a flame nor is the following statement meant as a flame:

What does 20 degrees difference have to do with combustion temps that are between 650-850 degrees? Is 20 degrees really going to have that much of an impact on combustion temps? I will agree that detonation is related to combustion temps. However, detonation is more directly related to combustion pressure, temperature, and fuel octane rating. In other words, you could have an engine running at 100 degrees, but if you are running too much boost for the octane fuel you are running, engine temp is going to do little to curve detonation. I will agree that a lower engine temp does play a part in preventing detonation, but as I said, that is a very small part and there are other factors that far outweigh it.

Sure you can run a lighter oil, but that still is not going to address the issue of operating temperature. Sure you can rebuild the engine with tighter tolerances so you can run colder temps, but what does that have to do with stock engines? Stock engines are designed to run with a 195 stat. I have seen many stock engines that exhibit major blow-by after just one season with a 160 stat. As I have been instructed, the oil in your engine needs to be at a certain temperature to work properly, regardless of weight. These specs can be found at the respective manufacurer's website.

Just to put it in perspective, why do racers preheat their engine oil?
 
Ok , one more question in regaurds to the the waste gate on the super charger or what ever you want to call it. My buddy and I have looked at this and noticed that it opens at about 8 to 6 pounds of boost. He thought that maybe if we put a needle valve in there to close it a little bit or in other words closing the valve more will hold more boost longer then dump the built up pressure in the block . Does anyone know if this would work or of anyone doing this
 
Boost Control System Description
Purpose
The boost control system regulates the induction boost pressure during rapid deceleration, during very high engine load situations, and any time that a reverse gear is selected.

(1) By-Pass Valve Actuator
(2) Boost Signal
(3) Boost Control Solenoid
(4) Boost Source
(5) Supercharger
(6) Intake Plenum
(7) By-Pass Valve
(8) Throttle
(9) Air Cleaner
(10) MAF Sensor
(11) Inlet Vacuum Signal

Operation
During most conditions, the PCM commands the boost control solenoid to operate at a 100 percent duty cycle (ON), keeping the solenoid valve closed and allowing only the inlet vacuum to control the position of the bypass valve. During idle, full inlet vacuum applied to one side of the bypass valve actuator diaphragm counteracts the spring tension in order to hold bypass valve open. When the engine load increases, the reduced vacuum acts upon the spring tension in the bypass valve actuator, causing the bypass valve to close and increasing the boost pressure. When the reduced boost pressure is desired, the PCM commands the boost control solenoid in order to operate at a 0 percent duty cycle (OFF). This opens the solenoid valve and allows the boost pressure from the intake manifold to counteract the spring tension in the bypass valve actuator, opening the bypass valve and recirculating excess boost pressure back into the supercharger inlet. With reverse gear selected, the PCM commands the boost control solenoid to operate at a 0 percent duty cycle (OFF) at all times.

Results of Incorrect Operation
An open boost control solenoid driver circuit, ignition feed circuit, or boost control solenoid valve stuck open will cause reduced engine power, especially during wide open throttle operation.

The boost control solenoid driver circuit shorted to ground, a boost control solenoid valve that is stuck closed, or a restriction in the boost source or in the signal hoses will cause full boost to be commanded at all times and may cause an overboost condition during high engine load situations.

A restriction in the vacuum signal hose to the bypass valve actuator or a stuck closed bypass valve will cause a rough idle and reduced fuel economy.

© Copyright General Motors Corporation. All Rights Reserved.

That is straight out of the GM service manual. Basically, I have never seen the PCM limit boost except when approaching the max speed limiter, or reverse/decel. If you want to prevent the PCM from cutting boost, simply remove and plug the vacuum line coming out of the boost solenoid that goes to the bypass actuator. Your SC will still operate normally, just the PCM will not be able to limit boost. DO AT YOUR OWN RISK! With this mod you will be able to get boost in reverse!
 
Ok but with the needle valve it will boost to whatever you want like say I set it for 10 pounds. When it hits ten pounds then the by pass valve will open. Its not like im just shuting the whole thing off just keeping it closed alittle longer
 
OK, i am getting a little confuse here. A supercharger does not have a wastegate. a supercharger has what is call a boost-by pass valve. this by-pass valve does NOT adjust boost. a supercharger will produce a fix amount of boost base on the pulley size. the boost-by-pass valve can be adjusted, but it does not adjust boost pressure at WOT. it allowed the s/c to create boost at a pre-determine time. this valve is very important when cruising at highway speed.

since the boost-by-pass is operated by a vacuum and a tension spring. i have been opening up the by-pass valve actuator and replace the spring with a spring that has less tension, so the boost come a lot quicker. this is not a mod for the street. running a less tension spring in the by-pass valve actuator will cause the s/c to draw power from the motor too soon and you will see a lose in gas mileage. when i am at the track i will install a by-pass valve actuator with the lease amount of spring tension this way when i stage the car the s/c is already making 6-8lbs of boost with a 2.8 pulley. this method makes the car a lot harder to launch, but practice make perfect.

so i hope i help in some way to answer your question.
 
Ok, first of all, GM calls it a boost solenoid, boost control solenoid, wastegate solenoid, depending on what publication you are looking at.

You are correct that it does not regulate boost pressure under WOT throttle. Therefore changing the spring inside would have no effect on performance other than determining when the bypass valve will close in relation to manifold vacuum. So in other words there is no point in changing that spring unless you want the bypass valve closing earler (in relation to throttle position/load). At WOT, the PCM is still going to command 100% duty cycle to the solenoid unless you are getting close to the factory top speed limiter as set in the PCM.

I did a test on my friend's 99 Regal GSE and found that his boost duty cycle began to fluctuate above 95mph which starter reducing boost. It felt like the car was surging but you could plainly see in the data stream that boost solenoid DC% was fluctuating. If you remove the vacuum line that connects the boost solenoid to the bypass valve actuator, the PCM will no longer have any way to cut boost. The actuator will still work as intended during decel and cruising modes due to the vacuum side still being connected.

Again, normally under WOT the bypass valve is closed, therefore allowing full boost. If you are experiencing some fluctuation in boost pressure you might be experiencing SC belt slippage.
 
Darth is exactly right. Adjusting the boost bypass valve, or changing it's internal spring pressure will have no effect on how fast boost ramps up on these engines. Full boost is nearly instantaneous with our roots-type blowers.

Scott
 
Originally posted by Darth Fiero
Ok, first of all, GM calls it a boost solenoid, boost control solenoid, wastegate solenoid, depending on what publication you are looking at.

You are correct that it does not regulate boost pressure under WOT throttle. Therefore changing the spring inside would have no effect on performance other than determining when the bypass valve will close in relation to manifold vacuum. So in other words there is no point in changing that spring unless you want the bypass valve closing earler (in relation to throttle position/load). At WOT, the PCM is still going to command 100% duty cycle to the solenoid unless you are getting close to the factory top speed limiter as set in the PCM.

I did a test on my friend's 99 Regal GSE and found that his boost duty cycle began to fluctuate above 95mph which starter reducing boost. It felt like the car was surging but you could plainly see in the data stream that boost solenoid DC% was fluctuating. If you remove the vacuum line that connects the boost solenoid to the bypass valve actuator, the PCM will no longer have any way to cut boost. The actuator will still work as intended during decel and cruising modes due to the vacuum side still being connected.

Again, normally under WOT the bypass valve is closed, therefore allowing full boost. If you are experiencing some fluctuation in boost pressure you might be experiencing SC belt slippage.
Click to expand...


I agree
 
rob, you need to remove STEVEXPERFORMANCE.com has a link to GFWC web-site. i don`t see why you are stealing my e-mail and using it for your GFWC web-site.


STEVEX IS NOT AFFILIATED WITH GFWC. so do your self the favor and remove STEVEX@GFWCperformance for you website. if you chosie not to do this i will have to take action into my own hands.

"I AGREE"

You are too bumb to agree with anything. loser. by the way when i see you, you best have all my money. cause all the parts are sold and you 2004 GTP COMP G motor is in MY car.

NOW what you going to do call your lawyer?....LOL.


if you do not remove all my picture and write up on your web-site i am have my lawyer draft a letter which will be mail to you...

get ready to be sue.....

why don`t you answer your phone?. are you avoiding all you fed-Ex and Ups bills. will i have taken care of that by having the company sent the bill to your customer and you...oh an by the way we don`t deal with comp-cam any more.. i am sure you will like to the 415HP in a 2004 GTP COMP G with NON Comp Cam camshaft.....THANK you


i told you i was two steps ahead of you...


STEVEX IS NOT AFFILIATED WITH GFWC
 
Originally posted by steveX
rob, you need to remove STEVEXPERFORMANCE.com has a link to GFWC web-site. i don`t see why you are stealing my e-mail and using it for your GFWC web-site.


STEVEX IS NOT AFFILIATED WITH GFWC. so do your self the favor and remove STEVEX@GFWCperformance for you website. if you chosie not to do this i will have to take action into my own hands.

"I AGREE"

You are too bumb to agree with anything. loser. by the way when i see you, you best have all my money. cause all the parts are sold and you 2004 GTP COMP G motor is in MY car.

NOW what you going to do call your lawyer?....LOL.


if you do not remove all my picture and write up on your web-site i am have my lawyer draft a letter which will be mail to you...

get ready to be sue.....

why don`t you answer your phone?. are you avoiding all you fed-Ex and Ups bills. will i have taken care of that by having the company sent the bill to your customer and you...oh an by the way we don`t deal with comp-cam any more.. i am sure you will like to the 415HP in a 2004 GTP COMP G with NON Comp Cam camshaft.....THANK you


i told you i was two steps ahead of you...


STEVEX IS NOT AFFILIATED WITH GFWC
Click to expand...

Last I checked www.SteveXperformance.com is not an EMAIL address. Seems to me like its a DOMAIN name that is registered to me.......
True Steve has no more affiliation with GFWC Performance. Steve is a roofer "Pro Roofing" thats where you send payment for automotive products..:rolleyes: ...lol

Robert
 
415 hp huh? Wheres the dyno sheet? Oh wait you have to pay for that stuff..... I suppose your going to tell us all that the car does 12's 1/4 miles now too? Pretty tough to get those times without a drivers liscense isnt it?

Proof bud thats what we all want to see.


Robert
 
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