then maybe it is the difference of his GTO tranny

 

even if you both start in 4th his gearing is more agressive he prob maxes out 4th at 110 and you still have a ways to go at 110 in 4th

 

The gearing in both cars is 1:1 in 4th gear, both cars have 4.10 gears, and both cars run the same size tire. Both cars will hit 120ish in 4th if you wind it out. On paper, gearing should be a non-issue in a long 4th gear pull.

That being said, the real world doesn't always mirror the paper world, so we're gonna try to get a good run from first on up and see if that makes any difference one way or the other. In that race he will have the gearing advantage (from the GTO trans), but in theory my HP should overcome that. I'll let you know.

Also, after swapping on the 28" MT radials tonight, the rear is noticeably more driveable in parking lots than it was with the Nittos, just as Fran said it would be.

 

As ScreaminRedZ said, fourth gear in both cars is 1:1 and we both have 4.10s, so the fourth gear pulls we did from 60-110 are legit. There is no advantage for either car. Same kind of car, same gearing, same weight, same everything except hp/tq. That's why I say it honestly appears to me that his car isn't really making any significant amount of power more or less than mine with the cutout closed. They were dead even from start to finish with no one pulling or falling back. I will be shocked if he gets it dynoed on the dyno I had mine done on and there's more than a negligible difference power-wise. There are no differences and the cars are dead even.

Who knows, maybe I'm wrong...

 

I talked to the guys at Harris Speed Works and they said that I can safely lean it out (on the 100 shot) a bit via correct jetting size. I believe that I will be able to carry my 100 rwhp gains out to the top of the pull by doing this. I also want to get my 125 and 150 jets squared away and see what it puts down.

 

The comparison to red and pewter's cars... only thing I can think of, is maybe that 400 rwhp # isn't dead accurate...

 

It's possible, but he's had it on the dyno several times and it's never made any more. Before he bought it, when it had the stock drivetrain it was making around 416 rwhp. I actually raced the car when the previous owner had it and our cars were very close then (I was making 420 cam only through the stock drivetrain at the time, so it makes sense).

Damn our never ending quest for more horsepower! haha

 

I did some math, I don't know how much heavier the TT2 wheels are, but "I figured it on 10 lbs each, if that's accurate then you're probably losing about 10 rwhp from them, that was figuring the weight is 13 inches from the center of the axle (screwy math it's not 100% accurate the way I figured but I think it gives the general idea)

That's just a rough guess... but if it's taking an extra 10 hp to accellerate that added weight from the rpm at 30 to 110, then that "could" be some of it.

There's also a good possibility of clutch slippage as well... not sure what the situation there is, same with traction even from a roll you could be spinning at a certain point where the other car isn't. I know my car when I was driving it would spin at the hit regardless the speed, granted the converter tq spike would cause that but still, this time of year with the roads being cold... it's possible. Hell my diesel pickup will blow the tires off like crazy if I punch it at anything less then 40 mph.

 

I'm no cam expert either but I think you are definitely leaving some upper rpm power with that lower lift cam even with that kind of duration. Those 215 heads really shine if you push up the lift closer to .600 and give it an aggressive ramp. With a split like that too you would probably see some top end gains getting rid of those cats.

If you revisit your cam choice I think you will really see a difference in power. Then you will also see how those $2,500 heads are suppose to stack up against a patriot head Those trick flows are being under utilized in the setup. Regardless though you did get some good gains outta them in your current config, close to 50hp is a great gain!

 

The 1.7 to 1.8 rocker ratio change gave him the lift into the 600 range.

 

Ahh I missed that detail


Well the only other thing I can think of if both cars pull even is maybe the TB is not reaching 100% open? I'd have to think the car should have a bit more pull above 100mph at a minimum.

I'd be curious to see track numbers with the same driver in each car.

 

Yeah thsy'd have to go to the track together and swap drivers to really see, but I don't think that's really gonna work because a stick car on a radial vs one on a bias ply is not a fair comparison IMO, plus the GTO gearing in pewter's car will prevent a bog better then adding 40 hp off the line IMO because of the 2.97 vs 2.66 ratio.

But, what do I know.

 

I hear you on the wheels, but they were on the car for the before and after dyno runs, so unless those losses don't show up on a dyno, it should have been factored in.

I doubt the clutch is slipping since it's very new and for the first time ever the hydraulics are working properly. Still a possibility, but unlikely I think.

I know that we weren't able to get a good run in from lower speeds due to traction. Even if the mine spun a little from 60 mph in 4th gear though, I would think the gains would be more at high speeds (high rpm) rather than down lower where we punched it.

Someone else mentioned the TB not opening, but if that's the case then it's a new problem that happened between the car being on the dyno (one day) and my runs with PSM (the next day). Regardless I'm going to check into it.

I strongly agree that a FAST and a bigger cam will provide decent gains. I still think that it should be pulling my brother's car since they were so close before and I picked up 40 rwhp. I guess the real test will be when I go to the track and see how my mph changes. If I only go 0-1 mph faster than I'll really be scratching my head.

Thanks for the ideas guys!

 

If you only go 1 mph faster, something is really wrong.

 

Just for the hell of it, I dynoed the car on another dynojet up here near me. The car made 424, then 422, then 424 back to back to back. Here's the graph for the best pull (best by about .5 hp, haha).



After comparing this one to PSM's (still a different dyno, but should be pretty comparable) it looks like the cars make similar power until about 5200 rpm and then mine starts picking up. If you look at his graph with the cutout open then he's definitely beating me under the curve. Looks like it's just a problem of my car being a torqueless wonder, haha. Hopefully my extra hp up top will allow me to run a better number at the track.

 

What cc are the heads again and what was the compression supposed to be? Because that tq seems WAY low, christ my cam only setup did 389 rwtq and that was back in 2003... with the parts and better tuning that's being done today... I'd be concerned with that.

I'd do a leakdown, compression check on the car and make sure all the cyl's are healthy, becasue that doesn't seem right to me at all. I know they tuned the car for some nitrous too, where is the timing at, and that pull what was the a/f?

 

Aw hell call me in about 5 min

 

what JL said, i mean i make 383 rwtq and i'm cam only with stock ls1 intake and TB. You should definitly be making more then that.

 

I have a feeling most of it is in his cam... With a 1.7 rocker i believe lift was only at like 550 or so. Thats why we did the 1.8 on it. I would love to see my RPM 3 cam in there.

 

Would a cam swap help out my torque numbers at all, Fran? The peak numbers are good because I'd probably be in the 440 range if I had a 10-bolt, stock driveshaft, and stock wheels, but with a weak mid range I think I'm going to lose to cars that make "less" horsepower.