I have been reading things here for a month or two. Trying to decide which type of bolt on Mods to do on my '98 Coupe. I was looking for good HP increase without any significant changes. I talked to a few shops in the past few weeks. Actually got talked out of a few mods that I might have made that they said would cost a lot with little to no real benefit.

After talking to a couple of good shops I was feeling a little discouraged.
Basically it came down to Head & CAm package or supercharging if I wanted much more. Anyway I had the bolt on stuff put on yesterday. Halltech tunnel Air, LS-6 Manifold, Throttle body bypass Granatelli high performance MAF, and GHL exaust 3.5 inch quad tips.

Let me qualify this by saying I don't know much about HP, dyno numbers etc. but I was looking to measure relative H.P improvements so I picked up a G-Tech Pro Performance meter.

Prior to going to the shop I made 2 runs through 1st & 2nd Gear only to the edge of red line. I only did the first 2 gears because of safety concerns (didn't want to go more then 80 MPH in a primarily residential area). They both came in @ 218 on the meter. Again, this # didn't mean much to me. Yesterday after I picked up the car I put around 35 miles on it. I know they
say it takes 50-60 miles for the electronics to relearn the new MAF settings and intake flow, but I was anxious this A.M and did not want to wait until tonight.

I made 2 runs this A.M and was shocked by the improvements both times just before red line it hit 325! My math says an 107 increase on the G-tech. I know I could not have picked up that much real Hp performance. I am going to go in and get a real Dyno (wish I had done it before I put the stuff on). I definetely can feel a nice increase with all this stuff in place.

For you DYno experts how does this all tranlate in the real world? Remember, I don't claim any expert knowledge.


[Modified by Bigben, 4:38 PM 10/10/2003]


[Modified by Bigben, 5:11 PM 10/10/2003]

 

your first runs were inacurate, remember the G-tech measure HP by using velocity vectors so driving make a big difference, so do tires and weather. on a stock vette the g-tech should read anywhere from 295-315 HP depending on year, milege, and weather. Your bolt ons are a good combo, and you should see as much as 30-40Hp from them, but 107 is outrageous. you should be aroune 330-340 hp may be a bit more with your mods. Also remember that the car is all wacked out with all the changes, it will recalibrate itself and u will loose some power

 

>>>your first runs were inacurate, remember the G-tech measure HP by using velocity vectors so driving make a big difference, so do tires and weather. on a stock vette the g-tech should read anywhere from 295-315 HP depending on year, milege, and weather.<<<

I agree that something was amiss due to the large difference but I have to disagree about the expected stock hp numbers. The G-Tech or for that matter any of the latest performance computers will always read lower than actual dyno numbers.

This is due to the fact that the G-Tech factors in aerodynamic drag when computing the hp figure. Example: Make 3 runs, throw out the high and low figure and keep the remaining hp reading. Make 3 more runs with the headlights up and the windows down and if its a coupe with the targa off. All of the hp readings will be lower even though there was no power change to effect hp.

On a dyno it dosen't matter since the car is stationary. The hp readings quoted are reasonable to expect for a stock LS1 on a dyno but not a G-Tech.

 

:cheers:

So It sounds like the numbers from this morning are about what I should expect with the mods I have done.

 

I'd say those numbers are close.

Here is a thread that you can check out.

http://forums.corvetteforum.com/zerothread?id=619927

 

:cheers:

Thanks for the info on the thread. New guys like me don't know a lot of what seems like common sense to those that have been around awhile. I must have been using the g-tech wrong on the first measurements and the most recent measurements of 325 with my mods may be a little light, but if what you say is true 325 makes sense. I thought I might get 330-340 with these mods. I will get the car dynoed somtime soon just to see. I didn't expect the g-tech to be 100% accurate, but figure it was a decent tool to measure relative improvements after modifications with out a dyno.

I will say that putting all the bolt ons that I bought on at one time made a big diference in the feel and power of the car. Mods= Halltech intake, Ls-6 Manifold, Granatelli performance MAF, Throttle body bypass and GHL Exhaust.