My car is super slow
Thread Starter
6th Gear
Joined: Oct 2018
Posts: 6
Likes: 1
From: Tx
My car is super slow
Hello, I own a 1992 C4 Corvette with an LT-1 and in my opinion my car is very slow. An average stock c4 corvette with an LT-1 runs a 13 -14 sec 1/4 mile pass.. on my particular vehicle I have made some mods. which are LT4 hot cam kit with heads, 58mm TB, edel brock manifold, hooker headers, borla exhaust, a slight bump up in stock compression, a cold air intake and some very beefy tires in the back, upgraded transsmission with shift kit, custom torque converter for 2500 RPM curve. Not sure what LB injectors I have and I run my 1/4mile no better than a 14 second pass. The take off feels great second gear kicks in with a alot of power but as soon as third gear kicks in my car boggs down.
Any sugesstion on to why my car runs like a stock anything i should check? maybe even a check list of things to check would be appreciated.
#TheGuyWithTheBlackVette
Any sugesstion on to why my car runs like a stock anything i should check? maybe even a check list of things to check would be appreciated.
#TheGuyWithTheBlackVette
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Hello, I own a 1992 C4 Corvette with an LT-1 and in my opinion my car is very slow. An average stock c4 corvette with an LT-1 runs a 13 -14 sec 1/4 mile pass.. on my particular vehicle I have made some mods. which are LT4 hot cam kit with heads, 58mm TB, edel brock manifold, hooker headers, borla exhaust, a slight bump up in stock compression, a cold air intake and some very beefy tires in the back, upgraded transsmission with shift kit, custom torque converter for 2500 RPM curve. Not sure what LB injectors I have and I run my 1/4mile no better than a 14 second pass. The take off feels great second gear kicks in with a alot of power but as soon as third gear kicks in my car boggs down.
Any sugesstion on to why my car runs like a stock anything i should check? maybe even a check list of things to check would be appreciated.
#TheGuyWithTheBlackVette
Any sugesstion on to why my car runs like a stock anything i should check? maybe even a check list of things to check would be appreciated.
#TheGuyWithTheBlackVette
Did you get a tune after heads/cam/exhaust?
If you're really tearing up first and 2nd gear...you should still ET decent even if it falters in 3rd gear. You'd have a decent ET but a low trap. I'm bet you don't have enough fuel....and I'm not talking about what's in the tank. Tank level don't matter by the time you get to 3rd gear.
Le Mans Master
Joined: Aug 2017
Posts: 6,944
Likes: 1,490
From: New Jersey
Need more info. What is your trap speed in the 1/4?
Did you get a tune after heads/cam/exhaust?
If you're really tearing up first and 2nd gear...you should still ET decent even if it falters in 3rd gear. You'd have a decent ET but a low trap. I'm bet you don't have enough fuel....and I'm not talking about what's in the tank. Tank level don't matter by the time you get to 3rd gear.
Did you get a tune after heads/cam/exhaust?
If you're really tearing up first and 2nd gear...you should still ET decent even if it falters in 3rd gear. You'd have a decent ET but a low trap. I'm bet you don't have enough fuel....and I'm not talking about what's in the tank. Tank level don't matter by the time you get to 3rd gear.
You could also probably look at the 1/8 time and see how it compares. If you're freight training there and fall off after you have a problem somewhere. Seat of the pants doesn't help, you need data to confirm as your butt dyno can lie.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
There is some telling info. Here is what I can share:
1. Your trap is decent for an LT1, but your ET is bad. What that means is the trap proves that you're making decent hp for a stock or stockish LT1....but you're making an inefficient pass. Where is the inefficiency for your HP? In the 60'. Your 2.183 should be a 1.9x...and that would put you in the high 13's at the same 101.xx. SO...there is some driving work to do there. What is your rear gear? As a comparison, MY box stock '92 runs 101-102 in the 1/4...but has ET'ed 13.75 on that trap. So improving the efficiency of your pass will drive down your ET w/no other changes, IMO.
2. Your ET is very poor for a cam/heads/exhaust LT1. You should be trapping at least 107 or better, IMO...and have a corresponding LOW 13's or even high 12's. The ET shows a massive lack of HP. Again, comparing your car and mine...we're trapping the same speed (making the same hp) and my car is stock....AND I'm running at 4500' elevation on 6000+ DA's. Your car is way down on power. Why? I bet it's in the tuning. You didn't mention if you'd had it tuned after the mods or not.
1. Your trap is decent for an LT1, but your ET is bad. What that means is the trap proves that you're making decent hp for a stock or stockish LT1....but you're making an inefficient pass. Where is the inefficiency for your HP? In the 60'. Your 2.183 should be a 1.9x...and that would put you in the high 13's at the same 101.xx. SO...there is some driving work to do there. What is your rear gear? As a comparison, MY box stock '92 runs 101-102 in the 1/4...but has ET'ed 13.75 on that trap. So improving the efficiency of your pass will drive down your ET w/no other changes, IMO.
2. Your ET is very poor for a cam/heads/exhaust LT1. You should be trapping at least 107 or better, IMO...and have a corresponding LOW 13's or even high 12's. The ET shows a massive lack of HP. Again, comparing your car and mine...we're trapping the same speed (making the same hp) and my car is stock....AND I'm running at 4500' elevation on 6000+ DA's. Your car is way down on power. Why? I bet it's in the tuning. You didn't mention if you'd had it tuned after the mods or not.
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Burning Brakes
Joined: Aug 2018
Posts: 891
Likes: 175
From: PA
Did you take it to the track when the engine was fresh or are you just now (3-4) years later doing it? If just now I would want to check out what the compression in each cylinder is. My other question is do you drive this car a lot or is it a weekend play toy verses everyday driver? Wondering about the miles verses the years after rebuild. Who did all the work? Like has been stated before you should be running much better times than you are. My basically bone stock 96 LT1 with auto trans and the 2.59 rear ran 13.70's all day at the 102-103 m.p.h. trap speed.
Team Owner
Joined: Oct 2004
Posts: 81,241
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From: altered state
St. Jude Donor '05
Did you check your fuel pressure under load? Id strap that down to a dyno, check your A/F readings and fuel pressure under load.
Could it be an ignition issue possibly....Ive seen cars with weak trans/converters slow a car down but doubt this is your problem. x2 on gears, too.
If you got the 3.07 or worse yet the 2.xx gears this is hurting you. If youre running a sec and a half slower than you should I bet youre leaner than a popcorn fart.
More cam you run the more gear you need so it pulls the way it was designed to. Youll see a lot of the LSx guys run a stock 2 series or 3.15 gears, a big cam and complain it doesnt run the internet #....cause they are worried about mpg and to boot wonder why it acts funny lugging it at low rpm.
Its all a package. Youll find it, usually something simple.
Could it be an ignition issue possibly....Ive seen cars with weak trans/converters slow a car down but doubt this is your problem. x2 on gears, too.
If you got the 3.07 or worse yet the 2.xx gears this is hurting you. If youre running a sec and a half slower than you should I bet youre leaner than a popcorn fart.
More cam you run the more gear you need so it pulls the way it was designed to. Youll see a lot of the LSx guys run a stock 2 series or 3.15 gears, a big cam and complain it doesnt run the internet #....cause they are worried about mpg and to boot wonder why it acts funny lugging it at low rpm.
Its all a package. Youll find it, usually something simple.
Last edited by cv67; Oct 19, 2018 at 07:22 AM.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
No. That might account for the poor 60'...but he should still be trapping a lot closer to 110 and he's not. Gears aren't going to kill your trap by 8mph. He ain't makin' the HP. The trap tells it all.
Drifting
Joined: Jun 2018
Posts: 1,678
Likes: 229
From: Michigan
Do you have a fuel pressure gage? Tape it to a window and have the passenger watch it. Does it start to fall off in the upper RPMs of 3rd gear? This would be an easier test before paying for dyno time. Hate to say it could be something simple, but when was the last time the fuel filter was changed?
Do you have any kind of scan tool? Can you watch knock counts? Do you feel any kind of sputtering north of 5K RPMS? Could be your opti.
You say your car feels slow, but has it always? did it feel faster 3 years ago?
Based off your times, I think you need to dial in your launch. Since you are an auto, are you brake torqueing? Do you turn the ASR off to allow a bit of tire spin? On street tires, you will 60' the best with just a slight bit of slip... not enough that the rear is sliding out, but just enough that you "hear" a little chirping. If you are not pushing the limit, you are leaving some launch power at the line.
Do you have any kind of scan tool? Can you watch knock counts? Do you feel any kind of sputtering north of 5K RPMS? Could be your opti.
You say your car feels slow, but has it always? did it feel faster 3 years ago?
Based off your times, I think you need to dial in your launch. Since you are an auto, are you brake torqueing? Do you turn the ASR off to allow a bit of tire spin? On street tires, you will 60' the best with just a slight bit of slip... not enough that the rear is sliding out, but just enough that you "hear" a little chirping. If you are not pushing the limit, you are leaving some launch power at the line.
Last edited by KyleF; Oct 19, 2018 at 11:19 AM.
Le Mans Master
Joined: Sep 2004
Posts: 6,019
Likes: 568
From: Conroe Texas
just a wag here but, do you still have your 48mm throttle body? or access to a 52mm? try replacing your 58mm for either of the 2 mentioned and making a pass. its like putting a 850 cfm holley on a 350 cid. sure, it'll run, even jet it down so it will not be over rich, but, the velocity isn't there.
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Drifting
Joined: Jun 2018
Posts: 1,678
Likes: 229
From: Michigan
just a wag here but, do you still have your 48mm throttle body? or access to a 52mm? try replacing your 58mm for either of the 2 mentioned and making a pass. its like putting a 850 cfm holley on a 350 cid. sure, it'll run, even jet it down so it will not be over rich, but, the velocity isn't there.
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Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
just a wag here but, do you still have your 48mm throttle body? or access to a 52mm? try replacing your 58mm for either of the 2 mentioned and making a pass. its like putting a 850 cfm holley on a 350 cid. sure, it'll run, even jet it down so it will not be over rich, but, the velocity isn't there.
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Safety Car
Joined: Sep 2001
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From: Glenbeulah Wi