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Discussion Starter · #1 ·
I usually run 1/8th, but finally got to a 1/4 track at Mokan in Asbury, MO. This is with my Chevelle.

LS1 swap, FAST 90mm intake/throttle body, Comp 230/224 lsa 111 reverse split cam (.57X/.56X lift), 1 3/4 longtubes, open cutouts 1 ft behind collectors, 25% underdrive pulley, 4l60E trans (highly built), Yank SS 3600 stall, 3.5" chromoly driveshaft, 12 bolt 3.42, 325/50r15 ET streets. Dynoed [email protected] with the converter unlocked and the cutouts closed.

This combo should be good for ~375-380+ rwhp EASY, but it seems to be missing 20+ hp.

DA 1842, I hit it about 1/2-3/4 throttle out of the hole and once I saw it was going to stick I hit it the rest hard. 1-2 went perfect, kissed my 6500rpm rev limit for a moment on the 2-3.

60 ft: 1.7776
330ft: 5.0621
1/8th: 7.8091
trap: 89.55
1000: 10.2091
trap: 101.81
1/4: 12.2473
trap:110.38

I feel like this trap speed is showing low for my mods. My raceweight should be right around 3700# with me in it.

I was expecting around a 112-115trap.

There was a 98 camaro 6 speed with: intake lid, ls6 intake, 1 7/8 headers, open exhaust, 9in 3.90 gears who was also trapping 110. He probably weighs within 100-150 lbs of my car.
 

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I would say thats not to far off. Aero could be hurting you and helping the camaro, might be why he trapped just as much as you.
 

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Discussion Starter · #3 ·
Whats funny though is if I go to Wallace Racing calculators and use my 1/8th mile info, I get:

Your HP computed from your vehicle ET is 394.61 flywheel HP and 355.15 rear wheel HP.
Your HP computed from your vehicle MPH is 433.56 flywheel HP and 390.20 rear wheel HP.

If I use my 1/4 mile:

Your HP computed from your vehicle ET is 358.91 rear wheel HP and 398.79 flywheel HP.
Your HP computed from your vehicle MPH is 358.63 rear wheel HP and 398.48 flywheel HP.


Could it be the combination of aero and kissing the limiter on the 2-3 shift that killed my trap? Or maybe the 1/4 mile estimate is just a more accurate gauge.
 

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Subtracting altitude,,, 0 DA,,,11.99
112.80
412 flywheel HP L J
 

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Kevin the conversions have never been accurate for me, they are calculated for idea conditions and don't account for the cars low, mid and high end performance (1/8th vs 1/4). Your launch method is probably costing you 1 or 2 mph....
 

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Discussion Starter · #6 ·
Thanks everyone for the ideas and opinions.

Davey: I was afraid of that. I tried the rest of the day to stick it hard out of the hole. It would bite for a moment then unload and spin. It was the first day the track was open. Also a combination of oil downs (gear oil no less), getting out of the groove once, and my suspension is a stiff setup for cornering.

I don't transfer weight a lot, and it seems like it recovers quick. If this is the best I can do on this setup I'm still more than happy and can fine tune it some. I have some ls6 heads waiting to be ported and installed. This should realistically bump me 20-30rwhp depending on my porting ability.

I would consider trying to get some drag shocks for the front to swap in on days I go to the track if I get them for a good price, not sure how much they would help.
 

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and don't get me wrong Kevin, I understand your need to do that. Don't get to caught up in dyno numbers, the only numbers that really matter are the ones on the slip. No weight transfer and a stiff suspenion is hurting you 60' for sure so it's just a matter of how you want the car set up. All of this considered I think your numbers are about where they should be....
 

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Thanks everyone for the ideas and opinions.

Davey: I was afraid of that. I tried the rest of the day to stick it hard out of the hole. It would bite for a moment then unload and spin. It was the first day the track was open. Also a combination of oil downs (gear oil no less), getting out of the groove once, and my suspension is a stiff setup for cornering.

I don't transfer weight a lot, and it seems like it recovers quick. If this is the best I can do on this setup I'm still more than happy and can fine tune it some. I have some ls6 heads waiting to be ported and installed. This should realistically bump me 20-30rwhp depending on my porting ability.

I would consider trying to get some drag shocks for the front to swap in on days I go to the track if I get them for a good price, not sure how much they would help.

I don't know how much difference a 90/10 shock would make if you use the springs you currently have, if they are a pro touring type spring. What tends to happen is with that type of short, heavy spring, is that with the 90/10s, the front end comes up a little, then goes right back down. And you just don't get good separation anyway. That's what happened with mine when I ran it like that. Then I got some santhuff's for the front and they work great at the track, but wouldn't be the spring to run for a cruiser.

If this car is a driver and that's mainly what you do, I'd leave the springs, etc., that you have now. But it never hurts to just throw on some cheap 90/10s and see what it does.

Maybe describe more what it does on launch. Is it launching straight? Do you have trick springs in the back, or an air bag or anything?Lift bars? No hops? boxed lowers? Tire psi? Burnout?
 

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Kevin - As a point of comparison, this past summer i dyno'd 349 hp on a dynojet and ran:
1.66
7.68 @ 89.5
12.09 @ 110.5
So i think if you work on the launch, you will be right there. Mine is a gen I sbc at 3500 lbs.

Tom
 

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Discussion Starter · #11 ·
Thanks again guys.

Front: circle track springs/height adjusters, 750# rate, stock SS bar hooked up
Rear: hotchkis springs, height spacer to keep rake (top of 28" tire is even with wheel opening, adjustable uppers, boxed stock lowers, stock SS bar, slapper type traction bars set right to the frame (see daylight between snubber and frame)

Set tires to 17psi, they are mounted on spare torque thrust IIs with only 3.5" BS just like my aluminum slots I run daily (295/50r15) so they rub on hard bumps, currently looking for wheels with 5.5" BS

Started burnout in 1st, held at 6000rpm then shifted to second and held at 4500rpm a few seconds and powered out, lifted before they bit

Don't get me wrong, I'm pleased...just making sure everything looks legit. :D
I was quicker than several trailer bound cars. I was pleased to drive there, change wheels, open cutouts and run. Should have disconnected the front bar too.

Then I got to drive home getting 20mpg at 70mph. ;)
 

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Kevin - As a point of comparison, this past summer i dyno'd 349 hp on a dynojet and ran:
1.66
7.68 @ 89.5
12.09 @ 110.5
So i think if you work on the launch, you will be right there. Mine is a gen I sbc at 3500 lbs.

Tom

What's you front suspension setup and what tires were you running? Converter?

Scott
 

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Thanks again guys.

Front: circle track springs/height adjusters, 750# rate, stock SS bar hooked up
Rear: hotchkis springs, height spacer to keep rake (top of 28" tire is even with wheel opening, adjustable uppers, boxed stock lowers, stock SS bar, slapper type traction bars set right to the frame (see daylight between snubber and frame)

h. ;)
People usually run one of three things. An Air bag in the passenger rear spring, a stiffer spring (like the moroso trick spring) or an anti roll bar.

One really cheap and easy route is to get one of those spring stiffeners that go inside the spring. You can get them at O'reilly's I think. My friend has one on his monte and it works good.
 

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I usually run 1/8th, but finally got to a 1/4 track at Mokan in Asbury, MO. This is with my Chevelle.

LS1 swap, FAST 90mm intake/throttle body, Comp 230/224 lsa 111 reverse split cam (.57X/.56X lift), 1 3/4 longtubes, open cutouts 1 ft behind collectors, 25% underdrive pulley, 4l60E trans (highly built), Yank SS 3600 stall, 3.5" chromoly driveshaft, 12 bolt 3.42, 325/50r15 ET streets. Dynoed [email protected] with the converter unlocked and the cutouts closed.

This combo should be good for ~375-380+ rwhp EASY, but it seems to be missing 20+ hp.

DA 1842, I hit it about 1/2-3/4 throttle out of the hole and once I saw it was going to stick I hit it the rest hard. 1-2 went perfect, kissed my 6500rpm rev limit for a moment on the 2-3.

60 ft: 1.7776
330ft: 5.0621
1/8th: 7.8091
trap: 89.55
1000: 10.2091
trap: 101.81
1/4: 12.2473
trap:110.38

I feel like this trap speed is showing low for my mods. My raceweight should be right around 3700# with me in it.

I was expecting around a 112-115trap.

There was a 98 camaro 6 speed with: intake lid, ls6 intake, 1 7/8 headers, open exhaust, 9in 3.90 gears who was also trapping 110. He probably weighs within 100-150 lbs of my car.
The wind was pretty strong yesterday was it a head wind or tail, i dont remember.
 

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I know you have to jack your car up to get the tires to fit, but it would be good to try running it with the rear lower than it is now. That might help.

How much separation do you get in the front suspension?
 

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Discussion Starter · #18 ·
I hear you. Unfortunately until I can afford or find some nice/cheap wheels with correct backspacing that won't be possible.

And since slots are the only commonly available used 15" I really like on the car and if I buy brand new wheels they will be 17s...It would essentially take me buying a set of 17s that fit correct AND a pair of 15s that fit correct.

The car doesn't have air shocks or anything, it sits the way it does naturally on springs/shocks. The drop would require trimming/removal of the height spacers under the springs and be permanent. And even still would only drop 1-1.5", I hate the stock ride height of chevelles, much less the extra 1" drop in the rear the hotchkis springs are advertised to give.

I understand I'm limiting myself there, but as stated above its about the compromise between drag racing (maybe ~10% of the cars use) versus street/cornering ability (85% of the car's use) and input 5% for aesthetic value to my tastes.
 

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It's always about compromising, and you are running good for the setup you have. Even without major changes, I bet you can knock off a couple of tenths still.

I don't like swapping wheels/tires all of the time between my slicks and street tires. It's pain. Though I am running slicks now, I am going to try drag radials next, I think, or at least a DOT slick so if I want to just cruise around town, I don't have to swap wheels.

You've got a few things to look at to tweak your setup some without losing the driveability that you have.

If you get a chance see what sort of front end separation you have. it would be interesting to know. Just measure the fender lip to the ground, then jack up the front until the tires are just about to come off the ground, then measure on the fender lip again in the same spot. For drag cars, 6+" is good, from what I understand. Not really a good thing for cornering, for a street cruiser.
 
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