c4 performance
Racer
Joined: Feb 2009
Posts: 486
Likes: 3
From: el cajon ca
Another great place to buy parts they have great pricing on Magnaflow just follow the directions for an email with your discounted price.
http://www.performancepeddler.com/default.asp
http://www.performancepeddler.com/default.asp
Thread Starter
Intermediate
Joined: Jun 2011
Posts: 46
Likes: 0
From: Eau Claire WI
So I verified that my axle ratio is the 2.59:1 not the performance 3.07:1 if I wanted to change this to the performance is there anything else that would need changing? I'm thinking maybe speedometer stuff?
Racer
Joined: Feb 2009
Posts: 486
Likes: 3
From: el cajon ca
you will be looking for around $1500 for the axle upgrade, and then a custom coputer tune to fix your speedometer, i have 2.59 too in my 91 auto, and i can smoke the tires at a dead stop easy, if i would be u, i wouldn't mess with the axle, just make ur car breath better with changing its exasut system
Instructor
Joined: Jun 2009
Posts: 119
Likes: 1
I had same issue when I got mine. I cleaned out the intake with carb spray and also added some gas treatment.The power came back after I used up the tank of gas that was in there and drove around more. could just be old gas
Team Owner
Joined: Sep 2001
Posts: 62,127
Likes: 1,727
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
You are looking for the fuel pressure to stabilize and hold steady while the car is running, then for it to hold steady after shutdown for several minutes.
Note what the pressure is, and note how long it takes to drop.
You do not need to spend the cash to go to 3.07 from 2.59 on an L98. Other mods should come first.
Note what the pressure is, and note how long it takes to drop.
You do not need to spend the cash to go to 3.07 from 2.59 on an L98. Other mods should come first.
Le Mans Master
Joined: Jun 2006
Posts: 5,642
Likes: 5
From: One day you're a Comet...the next day you're dust... Arkansas
You are looking for the fuel pressure to stabilize and hold steady while the car is running, then for it to hold steady after shutdown for several minutes.
Note what the pressure is, and note how long it takes to drop.
You do not need to spend the cash to go to 3.07 from 2.59 on an L98. Other mods should come first.
Note what the pressure is, and note how long it takes to drop.
You do not need to spend the cash to go to 3.07 from 2.59 on an L98. Other mods should come first.
Fix the exhaust and other low cost mods first. You would do well to look at Vader's site before spending a bunch of money.
Le Mans Master
Joined: Jul 2007
Posts: 5,356
Likes: 2
From: No HOA, New Hampshire
Cruise-In X Veteran
St. Jude Donor '09
you will be looking for around $1500 for the axle upgrade, and then a custom coputer tune to fix your speedometer, i have 2.59 too in my 91 auto, and i can smoke the tires at a dead stop easy, if i would be u, i wouldn't mess with the axle, just make ur car breath better with changing its exasut system
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Le Mans Master
Joined: Jul 2007
Posts: 5,356
Likes: 2
From: No HOA, New Hampshire
Cruise-In X Veteran
St. Jude Donor '09
Advanced
Joined: Oct 2009
Posts: 62
Likes: 0
From: Brantford Ontario
my 91 bogs from the line if you just stomp on it. hold the car with lightly your left foot on the brake, accelerate until the rears start to break free - give her more gas and let go of the brake, should smoke away with some practice. - old fashioned brake stand! 2500 RPM or there about.
Instructor
Joined: Nov 2009
Posts: 225
Likes: 1
From: Lake Hughes Ca.
St. Jude Donor '10
My '85 sat for a few years and was only started a few times. When it came time for the "smog check" it didn't pass due to the "cat". I put on a new cat and it passed. But, it was like driving a different car. Could it break the tires,,,,,,,, "you bet".
It will shock you how much a "blocked" cat can hurt performance
It will shock you how much a "blocked" cat can hurt performance
Thread Starter
Intermediate
Joined: Jun 2011
Posts: 46
Likes: 0
From: Eau Claire WI
well ordered a new front y pipe without precats and a new high flow cat. Cant wait to get them on the car. What other easy/low cost mods can be done to add power? Cat back is next not sure which one to go with tho. Apprecite the help.
Advanced
Joined: Jul 2010
Posts: 78
Likes: 1
From: Cape Town
What stupidity possesed GM to put in a 2.6 rear end in a performance car , I dunno!!!
I put in a 3.55 Ratio and my stock 86 is a different car , best bang for the buck upgrade. Tyres bust loose in 1st, 2nd and sometimes into 3rd. I now don't get embarrased at the stoplights. You actually will get better accel off the line if you can spin the tyres a bit but get grip as the motor gets into a sweet powerband. if you dont want to change the rear , you can try a higher stall torque convertor..like a 2500 street stall...
If you want good Mileage then get another type of car...
I put in a 3.55 Ratio and my stock 86 is a different car , best bang for the buck upgrade. Tyres bust loose in 1st, 2nd and sometimes into 3rd. I now don't get embarrased at the stoplights. You actually will get better accel off the line if you can spin the tyres a bit but get grip as the motor gets into a sweet powerband. if you dont want to change the rear , you can try a higher stall torque convertor..like a 2500 street stall...
If you want good Mileage then get another type of car...
Burning Brakes
Joined: May 2011
Posts: 838
Likes: 2
From: Louisville Ky
used 87 in my 91 for 3 yrs, never once heard detonation, tried 93 and saw ZERO noticable change, other than expense.
saludos
Racer
Joined: Mar 2007
Posts: 306
Likes: 0
From: New Hampshire
In my 1986 C-4 I can light up the tires [retty good and it is completely stock. When I first got the car, it seemed to lack power. I discovered a small leak on the intake. Changed the intake gaskets and it ran much better. My cars seem to run better a week after I take them out of the barn from being cooped up all winter. (I do start the cars every week though and let the oil flow) Drive the car with fresh (regular) gas and see if things smooth out. Don't waste money chasing a few horses.
Le Mans Master
Joined: Jun 2006
Posts: 5,642
Likes: 5
From: One day you're a Comet...the next day you're dust... Arkansas
Racer
Joined: Mar 2007
Posts: 306
Likes: 0
From: New Hampshire
We can spend a lot of money gaining more and more power, but now that the Mustang and Camaro V-6's have over 300 hp..It's a never ending pursuit!
