Frequently Asked Questions: Performance FAQ

[Supey]

Originally Posted by Kombi731

well done
that would have answered all my questions, and to think you don't even own a RL anymore

GREAT JOB, socal. This is very helpful. Hopefully I'll be able to find it when I need some answers.

[fullthrottle]

Originally Posted by icecruncher

Stock redline is 6450 instead of 6500.

Mike heres one that could be added. What is the stock fuel pressure at the test port on the fuel rail?

[socalsilverRL]

Originally Posted by TWoods450

i was just wondering why do you only hear the supercharger when your doin a hard acc. and not under normal driving?

Answer: because...your BYPASS VALVE is open under light to moderate acceleration, and during cruise. when you go WOT the 'GM boost solenoid' closes the butterfly valve in the in opening to your supercharger, and it starts taking air ONLY through the supercharger. Hence the 'whine' noise.
The bypass valve allows air to be diverted away from the supercharger rotors, so that the supercharger is not compressing air during light accel/cruise. That way the supercharger is only using 2-5hp to turn the rotors, versus 20-40hp (or 60, depending on pulley size) during WOT, when the SC is compressing air. End result, better gas milage, and a longer lasting valve train.

Originally Posted by Fullthrottle

Mike heres one that could be added. What is the stock fuel pressure at the test port on the fuel rail?

Answer: This is a good question, i will have to look further into this one...but, i remember reading somewhere that the fuel pressure is around 60psi. I believe that the fuel pressure may go up to 62psi during WOT, and taper down about 5-6psi at redline. WE ALL will need further info on this one. Here are a few links to some wonderful members that helped out:
Hooked up my fuel pressure sensor
Fuel Rail Pressure Data
NoRemorse also did a bit of fuel pressure testing, but im too lazy to look up his posts at the moment.
(more refference is needed)

[Hyperion]

Originally Posted by socalsilverRL

14) What's the smallest pulley I can run with the stock injectors?

A) 3.15 inches. That will net you about a 2psi gain over stock.

What does this equate to in power? I was thinking of getting a modular pulley system & putting a 3.15 on for now without any other engine/exhaust mods. Is it worth it to even bother? Also, how sure are you of 3.15 being the smallest/safest with stock injectors?

(edit: Also, is 3.1 okay? ZZP only goes as big as 3.1)

[fullthrottle]

Originally Posted by Hyperion

What does this equate to in power? I was thinking of getting a modular pulley system & putting a 3.15 on for now without any other engine/exhaust mods. Is it worth it to even bother? Also, how sure are you of 3.15 being the smallest/safest with stock injectors?

(edit: Also, is 3.1 okay? ZZP only goes as big as 3.1)

3.1 and 3.15 are pretty much the same thing. me personally I wouldnt even run a 3.1 with stock injectors but some say you can do it. The key is keeping the injector duty cycle with in the maximum amount. the industry standard on this is 80% IDC you need a way of loggin IDC to make sure. one way is to have HP tuners.

[Hyperion]

Bump for Socal or whoever else wants to input.

This really doesn't make sense because Stage 2 is 3.1 & uses bigger injectors so it seems to me that I'd run too lean. I don't have any means by which to monitor injector duty or anything else so I'm just looking for what's generally safe. I suppose I could get a 3.2 pulley from NHERBST454 but my question again is, "is it worth it?"

SoCal - is it worth it?
no, not really for the minimal gains youll get. Without being able to tune for the smaller pulley, you are better off leaving your car stock. I doubt you'd pick up more than 1mph in the 1/4mi. Your best bet is to go straight to a 3.0 or 2.8 pulley with larger injectors. Youll make more power that way.

Okay, thanks. I'm broke-dick so I'm gonna try to start buying parts here & there over a long time until I have everything equivalent to something like stage 3 & I was seeing if maybe I could get some fun out of just a pulley.

[fullthrottle]

Originally Posted by gsmith22381

i went with a 3.0 NHERBST454 on the stock set-up and it ran well you wont max out the injectors cause of the boost by-pass you will just boost faster.

So how do you know for sure that your injectors are not going over the industry standard 80% IDC? Are you logging it with HP tuners or some other logging program?

[ebristol]

Originally Posted by fullthrottle

So how do you know for sure that your injectors are not going over the industry standard 80% IDC? Are you logging it with HP tuners or some other logging program?

Do you know how GM determined its boost bypass level for the stock and stage 2 tunes? Stock is what, 12.5psi and Stage 2 is 16.5psi. Is it possible that they took that 80% IDC standard into consideration and set the boost bypass at that limit? Or am I giving GM too much credit?

SoCal - yea, im gonna go with, "too much credit." They put the boost bypass in there for 2 reasons, to get better fuel economy, and to save your valves.
you do NOT want boost, when you are under light load so that the S/C isnt parasitically taking all your power away.
Also, you dont want full boost when you are at 7200rpms, and hit fuel cut...*hanging valve makes out with piston*

Originally Posted by gsmith22381

going by what was said in another post
The much disputed maxxing out the 42#ers

can you measure that [Injector Duty Cycle] with an interceptor

yea you can.
you need to log INJECTOR PULSE WIDTH (IPW) vs. RPM.
Find the highest RPM, and what the IPW is at that RPM.

Then there are a bazillion IDC calculators all over the internet.
http://www.stealth316.com/2-calc-idc.htm

Your IDC is calculated based on how long the injector is open, versus the small amount of time there is on a ignition stroke. if your IPW is longer than the time available for it to inject fuel, then it is past 100% IDC. And you are most likely running wierd AFR's lean at 6-7K rpm, and rich at tip-in.

[fullthrottle]

Here you go. I've been holding out on you guy's. I actually have 2 more PDF files that are too large for me to put on here. I'll send them to Mike and maby he can do it.

Engine_Mechanical[1].pdf

ENGINE_CONTROLS_CONNECTORS[1].pdf

ION_PCM_CONNECTORS[1].pdf

[socalsilverRL]

^thanks Mike, I went ahead and updated the Fuel Pressure question.

<leaving more space for other questions>

Originally Posted by Supey

I saw this product on ebay called a gbox performance module. have you heard of products like this and are they any good or just a waste of money?

^waste of money.

most of those things are just a bunch of resistors, and capacitors stuffed into a plastic box. they arent designed to do anything...just a way to take your money.

Stay away from buying anything that claims "Instant MPG/x HP", and is a turbonator, electric supercharger, magnetic fuel line wrap, or 'chip' ...or anything similar to that. Like, Chin nuts...for when you have a hard time keeping the nuts on your chin spoiler...

Originally Posted by feelthequad

How much total horsepower? My goal for starters is at least 425HP. Just got rid of my Mach1 cause I have been seeing nopi challenge and I am quite impressed with the amount of HP these 4 cylinders are making. Got to see it formyself.

Your best bet is to find a good machine shop that can fabrcate everything for you. If you choose to keep the motor boosted with 400+HP, you will need a turbo.

Follow the 2.2L L61 GMPP build book, it goes over everything you need to achieve 400+hp. Just follow the instructions, and get your wallet ready...

If you want to have a good road track ready car, follow the Grand Am Cobalt build book, it retains a LOT of the engine stuff, and completely upgrades the entire suspension system.

Follow this link to the GM build books:
http://www.redlineforums.com/forums/382504-post3.html

or...

www.gmperformancedivision.com