Running at the track

[crash]

Took my Cutlass to the strip about a week ago and ran a best time of 14.33 in the 1/4 mile at 95 MPH. Coming up in June, I am hosting a car meet for another forum I am on and there will be a couple Pontiac G8s there, one is completely stock and the other has an intake and will have a dyno tune.

I know the G8 GT has 360 hp and they run a mid to high 13 sec 1/4 mile stock. I do not however, know what rear end gearing they came with, but I am guessing something like a 3.42.

I want to be able to run with at least the stock one and I have a set of Trick Flow heads ( http://www.summitracing.com/parts/TFS-3 ... /?rtype=10 ) with Trick Flow aluminum roller rockers ( http://www.summitracing.com/parts/TFS-3 ... /?rtype=10 ) that will be going on the engine in the next couple weeks.

I don't know the cam specs on the engine, but it does have 462624 heads on it which, from what I have found are complete crap with small valves and huge 76 cc combustion chambers. Without knowing the cam specs, do you think switching out the heads and stock stamped rockers will get me enough power to run with the G8s?

 

[pontiacgp]

from what I have read the GT has a 2:92 stock rear end and the GXP has a 3:27....

 

[khan0165]

what kind of intake and carb are you using?
... heads do alot, but you need to consider things outside the driveline...

suspension, tires, and even technique...

 

[crash]

Intake is a Holley street dominator, but it is not like the new ones offered from Summit that are dual plane. It is a single plane with a center divider.

Carb is an Edelbrock 1405, either 600 or 650 CFM, I can't remember for sure off the top of my head. I will likely be looking for a 750 CFM when I do the swap as well.

 

[pontiacgp]

I'd stick with a 650 carb.....750 you'll be dumping fuel...and the single plane intake is costing you time on your launch

 

[khan0165]

I'd stick with a 650 carb.....750 you'll be dumping fuel...and the single plane intake is costing you time on your launch

I agree, there's no need to go to a 750
and with your combo, a single plane might be too agressive to do any good.

it would be very interesting to find out what cam you have, but ofcourse that will happen when you take few other things off.

before you do anything drastic, try working with what you have. You won't get it fast the first time. Work on your launch... See if you can leftfoot brake and bring the revs up before you launch. If you are doing a burnout, try staging in a clean line, where there isn't rubber built up from the last guy.

Also, if the car is an auto, try shifting it yourself. I do not recommend reving to 6000 until you find out where your powerband is. Try to notice the rpm where you feel the car start to struggle (I'm guessing it would be around 5000-5500rpm). Then shift at that rpm.

I know that in my car, the shift points are setup at 4000rpm... but the cam doesnt even come in until 5000, and peaks at 6000. So when I race, I shift the auto myself. It takes a bit of practice...

what rearend do you have? what gear? Gearing really helps, specially if your car is not strong in the top end. More agressive gears (like a 3.73) will help your engine rpms through the traps. Of course, you'll need to decide if you want to compramize any road driveability.

Are you racing on those 17" tires? Try going to a smaller wheel with taller tires... It will be more gushy, and grab the track better at launch. Try lowering the tire pressure... If you're running your 17s, I would not go much lower than 20psi... if you are running 15s, try lowering it to 17 or 18psi.

At 95mph, you should be running a 14.0 or 13.9... maybe even a 13.8... Just work on your technique, and you'd be surprised.

 

[crash]

Rear end is a 3.73 posi and the trans is a 200-4R. I was launching at about 3k rpm and getting 2.0 60' times. Certainly not the best, but I ran about ten runs and they were all between 14.33 and 14.47

I am running my 17s and doing just enough burnout to clean them up. I also will not be switching to a 15" rim / tire combo anytime soon. There is no reason I can't hit mid to high 13s with the 17s

 

[dogsht]

Khan what does your car run? Nitto & others make a drag radial in a 275/40/17 that would be a lot of help. Your sixty foot & or quarter mile times are about right for 95mph gbody. My GN ran 13.90s at 98 mph when it was brand new & box stock. Aside from the tires, heads, headers, cam, & converter will be where you get better et/mph from unless something is sic or terribly mis matched. 3k launch do you mean your converter flash stalls to that now & that your are holding reasonable traction there. If so that is probably pretty ideal for a street to street/strip combo. But I bet that is not the case. My cars run/ran 1.8s with 2,800 & 3,000 stall lock up converters.

 

[crash]

When I launch, I hold the brake and get the engine up to 3k RPM then go WOT at the light, and wasn't spinning. I figure when I swap the heads over, I will have to be a bit more gentile with my launching.

I believe the converter is factory.

Here is a complete rundown of the car...

K&N filter
Edelbrock 1405 carb
Holley Street Dominator intake
Junk factory 462624 heads with 76cc combustion chambers with likely 1.94 / 1.50 valves
Factory stamped steel rockers
No idea on cam specs or piston specs, so no clue on compression
200-4R trans
3.73 posi rear
255/45/17 summer performance tires (not slicks)

I am going to swap out the heads and rockers for my Trick Flow heads and aluminum full roller rockers.
2.02 intake / 1.60 exhaust
64cc combustion chambers
195 cc intake runners
75cc exhaust runners

1.5 ratio roller rockers

I found on another forum that a guy switched from these 624 heads to a set of Dart iron eagle heads and gained 5 mph and .75 seconds in the 1/4 mile. Probably irrevelent information in my case, but just goes to show how bad these heads are.

Basically I just want to know if you guys think that with the information I have provided that I know, do you think I can possibly pull off a mid to high 13 second 1/4 mile with everything else being the same except the heads, roller rockers, and maybe carb. I ran a 14.33 @ 95 mph with a 2.0 60ft a week ago with the 624 heads.

 

[khan0165]

I don't know of any stock trans that can let you hold the brakes at 3k rpm... You might have a stall in that thing...

anyways... it seems like you're doing all the right things. If your wheels aren't spinning, you're likely getting a good launch with good traction.

Unfortunately, I'm not knowledgeable enough to say how much you will gain by changing your heads. But you will definately gain something! Have you thought about doing the cam when you do the heads? It'd be a bummer if the cam turned out to be a bad combo for the new heads after the swap.

just my 2cents...