So I hooked up my G-Tech finally and took her for a run. The thing said I had 171 horsepower, 169 horsepower, and 172 in 3 runs.
So I was wondering if anyone knows what this translates into, is it rear wheel horsepower or is it flywheel.

And I was wondering if these are pretty good numbers for my LG4.

My mods are in my signature, but basically the car is stock with 129000 miles.

I didnt get a chance to run the 1/4 and 60mph times yet, dont need a ticket, besides I want to get it to a track and get some real times.

 

Sounds to me like rwhp. Maybe 15's?

 

those are pretty good numbers for an lg4

 

That the power it gives is the actual calculated amount of hp being produced and used. So rwhp would actually be higher because the G-tech is measuring other effects (drag, friction)then a rwhp dyno. So you may have slightly more rwhp because it takes more power due to drag.....

 

The G-tech can only give you RWHP; it has no way of knowing what the engine is putting out, only what power is moving it.

The most common error in one is to enter too low of a car weight. That will cause it to tell you it has more HP than it really does, because it thinks more weight is being accelerated than what really is.

The LG4 in 86 was "rated" at 160 HP at the flywheel. It usually puts 130 or so to the wheels. An indication of 170 RWHP on a stock LG4 is highly suspect.

 

I think that's backwards.

The G-Tech figures HP by using weight and acceleration. If you enter 3,000 lbs and go 0-60mph in 7 seconds, then enter 3,500 lbs and go 0-60 in 7 seconds, it would take more HP to accelerate a 3,500 lb. car than a 3,000 car.

Right?

 

Well, I have entered 3200 lbs as my curb weight. The car is a basic SC without power windows, pwr door locks, in fact this car has nothing. Now I said the car is basically stock, I didnt say it was completely stock. It does have some mods.
Such as:
To start, a dual snorkle air cleaner with K&N, 1 5/8" shorty headers into a high flow cat , 3" H.O. pipe back to 2 1/2" Dynomax muffler. 160 degree Thermostat, MSD 6A, pertronix coil, cap and module with advanced timing. A chip(supposedly a Superchips) that I got from a local programmer(not sure it did anything, seat of pants meter indicated nothing) Not to mention the 3:73 posi.
I am just trying to decide whether it is worth it add a couple more items, such as intake, cam, roller rockers, carb. that kind of stuff.
So RB83L69 does this change anything?

I mean I am not looking to go drag racing or anything, I just want something to run respectfully is all .

 

The curb weight you entered seems a little generous. An '87 IROC with a 5-speed weighed approximately 3300lbs. from the factory.

 

so Nate does this mean I am to heavy or to light with my weight?

Also I am aware that a G-Tech is not especially the best way to judge anything, the only true test is with a Dyno and a couple of track runs.

 

I'm not saying your car is heavier or lighter than that. Obviously the only way of really knowing how much it weighs is to just go weigh it somewhere.

I'm guessing your car is actually a little heavier than 3200lbs., though. Like I said before, an unoptioned 1987 IROC-Z with a 305 V8 and a 5-speed weighs about 3300lbs. There are a few things that were already on your car to make it a little heavier than the 87. The 700R4 adds about 100lbs. to the car's weight. I don't know if you have A/C but that adds about 50lbs. if you do. Even little things that you wouldn't normally think about begin to add up after a while. Cruise control, disc brakes, a rear window defogger, a rear window shade, and even floor mats add some weight to your car. And, although this is only an assumption I made based on my observations, I believe that your 86 may have had an even higher curb weight from the factory than the 87. Data shows that the f-bodies actually lost weight as the years progressed. Again, this is only an assumption... don't take it to heart.

The stuff that you have done to it probably all evened out. Headers probably lost some weight, while the exhaust piping probably gained some weight. The air cleaner probably added a couple of pounds.

Anywho... if I had to guess, I'd say your car was probably in the 3350-3500lbs. reigon. I could be way off, but I wouldn't put my money on 3200lbs.

EDIT: I forgot to mention that I agree with RB. 170RWHP seems a little bit high for only what you've done. Exhaust and induction mods help... but not ~50HP worth.

 

And don't forget about YOU.

I, for instance, weigh 230 lbs. That takes a 3400 lb car to 3630. That's ~.2 seconds SLOWER in the 1/4 mile.

Then there's the weight of the fuel, which "curb weight" uses (IIRC) 1/2 tank.

You really need to have your car weighed if you aren't able to find a chassis dyno near you.

 

:hail: AJ! I completely forgot about that!

 

If you put in more weight like you should, you will get more horsepower. So your making quite abit or something....

 

Cool , Thanks guy's you have really put things in perspective. I didnt think about any of that stuff.
Guess I'll be ordering that 383 crate motor now !!

Thanks again for all you guys input.

Oh yeah, I forgot to say that I also have an aluminium drive shaft, that has to account for some weight loss, but it does have a/c and the 700r4, and I weigh about 200lbs, but it really doesnt have much else.

Maybe I should hook up my Nissan Titan to the G-Tech and see what that runs, its supposed to be 305 HP

 

I still think the Camaro is much more pleasing to the eye, even though it is probably alot slower

 

Weighed mine this summer without me in it and go 3340lbs.

87 Firebird auto with AC and thats about it.

lots of mods in sig, panhard rod was added after weigh in

 

I think I am going to throw out that G-Tech, never use it again. Thanks Pre for making me realize its time to just find a nice 02 SS.

 

A G-tech is a decent tool that saves time and money when compared to using a dyno or dragstrip. Only problem is you have to be honest with the data. A friend of mine has a 350 in a mazda RX7 and it mede 298 and 297 according to his G-tech. On the same day he put it up on a chassis dyno and it made 301 and 297 RWHP. Pretty accurate if you ask me.

 

My thing with the G-tech is even if it isnt accurate, it is consistant. So you can make a mod, G-tech. make a tune, G-tech.

you can basically assess how much faster your car is getting, even if you dont know exactly how fast it is till you hit the strip.