Why does my car under perform?
Thread Starter
Drifting
Joined: Aug 2003
Posts: 1,360
Likes: 1
From: Austin Tx
St. Jude Donor '08
Why does my car under perform?
I have a 99 FRC and no matter what mod I do it always under performs.Just a few examples:
(old setup)
Stage II H/C w/MTI X-1 Cam
TPIS 1 3/4 LT w/Hi-flow cats
3.90 gears w/harden output shafts
Corsa
total HP:390RWHP
added 150 TNT kit 530Rwhp
(new setup)
408 iron block 10.8-1 CR
Lunati Crank
Lunadi Rods
Wiesco Pistons
Stage III heads
MTI S-1 Cam
90/90 Fast intake
1 7/8 Kooks
Hi-flow cats
Corsa
3.90 gears w/harden output shafts
480RWHP
All the work has been done by MTI in Houston.
What could be causing the car to not put out the HP it should?
(old setup)
Stage II H/C w/MTI X-1 Cam
TPIS 1 3/4 LT w/Hi-flow cats
3.90 gears w/harden output shafts
Corsa
total HP:390RWHP
added 150 TNT kit 530Rwhp
(new setup)
408 iron block 10.8-1 CR
Lunati Crank
Lunadi Rods
Wiesco Pistons
Stage III heads
MTI S-1 Cam
90/90 Fast intake
1 7/8 Kooks
Hi-flow cats
Corsa
3.90 gears w/harden output shafts
480RWHP
All the work has been done by MTI in Houston.
What could be causing the car to not put out the HP it should?
Last edited by HIGH_INTREST; Aug 17, 2005 at 08:40 PM.
Racer
Joined: May 2003
Posts: 306
Likes: 1
From: Austin TX
Dont feel too bad Shawn... My MTI stage 2e heads and X1 cam only made 400 rwhp with the stock 3.42. I wonder what your Iron Block makes for torque? 480 isnt stellar but its no slouch especially with the 10.8:1 CR. Dont forget that those cats are sucking up the power as well as the 3.90s on the dyno.
Chin up
Just spray it and be done!!
Chin up
Just spray it and be done!!
Drifting
Joined: Nov 2002
Posts: 1,776
Likes: 5
From: Midlothian Texas
St. Jude Donor '12-'13-'14-'15-'16
Originally Posted by HIGH_INTREST
I have a 99 FRC and no matter what mod I do it always under performs.Just a few examples:
(old setup)
Stage II H/C w/MTI X-1 Cam
TPIS 1 3/4 LT w/Hi-flow cats
3.90 gears w/harden output shafts
Corsa
total HP:390RWHP
added 150 TNT kit 530Rwhp
(new setup)
408 iron block 10.8-1 CR
Lunati Crank
Lunadi Rods
Wiesco Pistons
Stage III heads
MTI S-1 Cam
90/90 Fast intake
1 7/8 Kooks
Hi-flow cats
Corsa
3.90 gears w/harden output shafts
480RWHP
All the work has been done by MTI in Houston.
What could be causing the car to not put out the HP it should?
(old setup)
Stage II H/C w/MTI X-1 Cam
TPIS 1 3/4 LT w/Hi-flow cats
3.90 gears w/harden output shafts
Corsa
total HP:390RWHP
added 150 TNT kit 530Rwhp
(new setup)
408 iron block 10.8-1 CR
Lunati Crank
Lunadi Rods
Wiesco Pistons
Stage III heads
MTI S-1 Cam
90/90 Fast intake
1 7/8 Kooks
Hi-flow cats
Corsa
3.90 gears w/harden output shafts
480RWHP
All the work has been done by MTI in Houston.
What could be causing the car to not put out the HP it should?
Advanced
Joined: Jul 2005
Posts: 74
Likes: 0
hmm, i'm coming from a general performance background, but since you've changed engine setups and according to you its still under what was expected, I'm assuming your running a decent clutch so it can't be the clutch, maybe something is wrong with your transmission? Maybe check your grounding points but that shouldn't be a problem since you have a fairly new car.
What did you use to tune? And how aggressive is the tune? Any dyno charts? Tuning is really key, maybe your tuner felt a conservative tune would be better?
What did you use to tune? And how aggressive is the tune? Any dyno charts? Tuning is really key, maybe your tuner felt a conservative tune would be better?
Thread Starter
Drifting
Joined: Aug 2003
Posts: 1,360
Likes: 1
From: Austin Tx
St. Jude Donor '08
He is using LS1 edit and you might be right about being conservative.I guess it would be better safe than sorry.I am supposed to get the car back w/d-1sc on Saturday w/dyno sheets.I will post them when I get them.I should be in the 700RWHP range.
Safety Car
Joined: Oct 2000
Posts: 4,949
Likes: 10
From: Monticello MN
Originally Posted by mdhmi
Your numbers sound on par to me. Keep in mind that many of the numbers you see floating around the internet are total bull.
Mark
Mark
Dyno numbers mean absolutely nothing unless they're SAE corrected and smoothed. Plus I think a lot of people think that a G-Tech number is accurate or add up the claimed power increase on their mods.
Ed
Melting Slicks
Joined: Oct 2002
Posts: 2,855
Likes: 0
The diff in 10.8 and 11.3 cr could be 30rwhp---cats at least 10rwhp and your 390s are costing at least 10rwhp-of course we have no idea what the specs are on your cam but you could be well over 500rwhp with the 3 things mentioned.--also keep in mind the humidity in Houston is the same as FL and no corrected figures are acurate in this kind of humidity we have proven it time and again in Florida--
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Burning Brakes
Joined: Dec 2003
Posts: 1,074
Likes: 0
From: Dallas (Go Cowboys!!!) :) Tx
Originally Posted by NavyBlue99
Dont feel too bad Shawn... My MTI stage 2e heads and X1 cam only made 400 rwhp with the stock 3.42. I wonder what your Iron Block makes for torque? 480 isnt stellar but its no slouch especially with the 10.8:1 CR. Dont forget that those cats are sucking up the power as well as the 3.90s on the dyno.
Chin up Just spray it and be done!!
Chin up
Just spray it and be done!!Everything done there. I think they are very conservative w/ their tunes.
Thread Starter
Drifting
Joined: Aug 2003
Posts: 1,360
Likes: 1
From: Austin Tx
St. Jude Donor '08
Originally Posted by AMERICAN_HP
Your running 10.8:1 AND a D1SC?? 
Did you drop comp, or are you gonna run less boost??
Did you drop comp, or are you gonna run less boost??There will be some timing taken out and less boost.
Thread Starter
Drifting
Joined: Aug 2003
Posts: 1,360
Likes: 1
From: Austin Tx
St. Jude Donor '08
Originally Posted by Tru_Ice
Yeah I pulled 405/380 w/ Stage IIe's , LTs, Vararam, High Flow Cats, X-pipe, Borlas, and a 224/228 cam through an A4. Got any track times guys?
Everything done there. I think they are very conservative w/ their tunes.
Everything done there. I think they are very conservative w/ their tunes.
Safety Car
Joined: Jul 2001
Posts: 3,667
Likes: 0
From: TurtleCreek Twp Ohio
Cruise-In III Veteran
Originally Posted by Tru_Ice
Yeah I pulled 405/380 w/ Stage IIe's , LTs, Vararam, High Flow Cats, X-pipe, Borlas, and a 224/228 cam through an A4. Got any track times guys?
Everything done there. I think they are very conservative w/ their tunes.
Everything done there. I think they are very conservative w/ their tunes.
122-123 traps are common when the weather is under 70`, 120-121 when the weather is in the 90's. 130traps with the 125 shot regardless of weather.
Thread Starter
Drifting
Joined: Aug 2003
Posts: 1,360
Likes: 1
From: Austin Tx
St. Jude Donor '08
Originally Posted by Aquaman
I have 409/390 with Cartek Stage II heads a 218/222 cam (old Cartek M cam) with No cats, FLP headers, Stingers, Vararam, LS6 intake and ASP pully, with the stock rear on an MN6
122-123 traps are common when the weather is under 70`, 120-121 when the weather is in the 90's. 130traps with the 125 shot regardless of weather.
122-123 traps are common when the weather is under 70`, 120-121 when the weather is in the 90's. 130traps with the 125 shot regardless of weather.
The funny thing is I'm not complaining about the times I get it's just it doesn't perform well on the dyno.My car runs:
11.50 @119 on motor
10.80 @128 w/150 shot
best 60ft was 1.55
Le Mans Master
Joined: Jul 2002
Posts: 6,147
Likes: 32
From: Dallas TX
Its prolly just a comination of little things man. cats, 3.90 gears, corsa catback maybe, you can add more compression and still run pump, more duration on the cam, and it is kinda hot in Texas right now.
Just little stuff like that can be 30-40rwhp easy.
do you have underdrive pulleys? what CAI?
Just little stuff like that can be 30-40rwhp easy.
do you have underdrive pulleys? what CAI?
Le Mans Master
Joined: Jul 2002
Posts: 6,147
Likes: 32
From: Dallas TX
Oh and I really thing its a BAD idea to put a blower on that exact setup. If nothing else, go with some bigger heads (72cc) and a lil thicker head gasket to get static compression under 10:1.
Safety Car
Joined: Jul 2004
Posts: 3,706
Likes: 2
From: Valrico Florida
I think your numbers are right on par. Your H/C package should have been more in my opinion, but your 408ci with the cam and compression seems about right. I am sure your timing is very conservative. If it is above 28 degree's I would suspect closer to 500rwhp. If it is really bothering you pull the heads off and have them flowed by Thunder Racing or someone.
Safety Car
Joined: Jul 2004
Posts: 3,706
Likes: 2
From: Valrico Florida
Originally Posted by HIGH_INTREST
The funny thing is I'm not complaining about the times I get it's just it doesn't perform well on the dyno.My car runs:
11.50 @119 on motor
10.80 @128 w/150 shot
best 60ft was 1.55
11.50 @119 on motor
10.80 @128 w/150 shot
best 60ft was 1.55
Thread Starter
Drifting
Joined: Aug 2003
Posts: 1,360
Likes: 1
From: Austin Tx
St. Jude Donor '08
Originally Posted by Vince99FRC
I just saw this.. What tires were you running when you ran these times? Also, do you consider yourself a good driver?
I am running CCW's w/ET Streets.I guess I would consider myself a decent driver.
