I can't get any mph out of my car!

[Heath]

I have went to the track ran 11.91,11.94,at 108,109 mph.I thought my converter was to loose so I changed it to a 3400 ART CARR non lockup. I am going to the track this weekend to try it out but it still feels like it does not pull that hard in third.

 

[Syclone0044]

Same Problem

I've got the same problem in my Syclone, I used to run 11.7 @ 114 with the stock converter 2 years ago, now I have a 2700 stall converter that is pretty tight but I added more alcohol and despite 11.5 AFRs I can't get it to MPH beyond 111 even with more boost, more timing, better launch, and less knock.

Post up if you figure it out!!

 

[Heath]

No mph.

I hope someone else will chime in and fix our problem

 

[bison]

Post your rpm at the end of the quarter mile, tire height exactly as the car sits on them, what kind of tire, and rear gear if you changed it. Drag slicks will grow in height at high mph. Your mph on your time slip is your average mph for the last 60' of the quarter, not your actual mph as you cross the line. If you post your numbers we can figure out your converter slip %. It should be under 10%. With an old Art Carr 16930 in my friends 127+ mph car it slipped around 9%. He was picking up nearly 27 mph from eighth to quarter.

 

[Heath]

No mph

With my old converter
5900 right before the traps I shifted into overdrive. I didn't want to run the rpms up any higher.
tire size-275-60-15 MT drag radial
373 gear
My previous converter was also a ART CARR 9 inch. Exept it was 3000 stall and the one I have now is 3400. Both are non lockup.

 

[Heath]

I have not went to the track with the current converter yet. I am going this saturday.

 

[c&cgn]

With my old converter
5900 right before the traps I shifted into overdrive. I didn't want to run the rpms up any higher.
tire size-275-60-15 MT drag radial
373 gear
My previous converter was also a ART CARR 9 inch. Exept it was 3000 stall and the one I have now is 3400. Both are non lockup.

The 3.73's are killing you for sure, and the rpm may be too high depending on what cam you have.

My car likes being in the 5700 -5800 range but I'm running 130+ mph.

 

[justabuickv6]

Based on what has been stated, I think it's the gear that is the issue.

 

[Heath]

No mph

My cam is a 210-205. I have no idea what rpm this cam is done making power at. What gear do I need? I am running a 28 inch tall tire, I figured that would be close to 342s with a 26 inch tire. Am I wrong for thinking this.

 

[Ed Valvo]

What valve springs do you have? Are your heads Aluminum or Iron GN1's? Recently people have been told that the Champion Irons are also called GN1's.... Lastly, what boost are you running?

 

[justabuickv6]

The GN1's are alum. Champion irons are stock CNC ported heads (8445).

If you haven't replaced your valve springs, I would highly recommened doing so if you have some miles on the motor. I picked up 2 mph when I did so.

 

[RegalX]

I have a very similar problem. with a small block, th350 and 3.42's i've gone as fast13.34 and 13.40's all day at 104mph. That was with a 2400 stall. I put in a 3000 and now i cant trap over 100mph. I am pretty sure I overstalled the car, I was thinking of going to 3.73's since i cross the line at only 5100rpm. What is the formula to calculate converter slipage?

 

[justabuickv6]

A lockup would help.

I have a 9x11 3600 CK converter. When I lock mine, it's good for 4-5mph in the 1/4.

 

[Heath]

No mph.

My heads are aluminum.
I am running 20 lbs of boost.
My motor and heads have 3000 miles on them.
The chip I run is burned for alky, FULL THROTTLE burned it for 98 octane. I have no idea what timing I am running or if that is the problem.

 

[bison]

Use the following link to calculate your rpm at different mph's.
http://www.csgnetwork.com/multirpmcalc.html

 

[bison]

Heath, according to the calculator you should be at 4879 at 109 mph at 1:1. You stated you were shifting at 5900 into OD. Assuming it was actually 5900 as you crossed the line you would have 20.9% slippage . This doesnt seem possible unless the converter is broken or clutches are slipping in the transmission. With 10% less slip you would go 10% faster just from the increased efficiency. You would be at nearly 120 mph like you should be.

 

[bison]

I have a very similar problem. with a small block, th350 and 3.42's i've gone as fast13.34 and 13.40's all day at 104mph. That was with a 2400 stall. I put in a 3000 and now i cant trap over 100mph. I am pretty sure I overstalled the car, I was thinking of going to 3.73's since i cross the line at only 5100rpm. What is the formula to calculate converter slipage?

You should be at 4268 rpm with no slip at 1:1 with a 28" tire. Your slipping around 20% also. Ive seen a lot of s hitty converters eat up a lot of mph. Ive rarely seen an Art Carr eat up more than 11%. My friends car was slipping 9% and that was in a car going 127mph at 3750lbs! You cant use the stall speed to determine efficiency. Ive seen low stalls that suck up top.

 

[norbs]

I'd say the converter is broken inside, or the direct clutches are smoked in the trans!at 5800 rpm i am doing 130 mph with a 3.73 gear and 28" tire in lockup and the converer/tranny is still slipping, even locked

 

[Heath]

No mph

This is my second converter. I have not went to the track with this converter yet. I have got on it hard on the street and after third gear hits it just stops pullin.Is it possible for the clutches to be burned up in third gear and the fluid in the transmission to look fine

 

[bison]

This is my second converter. I have not went to the track with this converter yet. I have got on it hard on the street and after third gear hits it just stops pullin.Is it possible for the clutches to be burned up in third gear and the fluid in the transmission to look fine

Fluid would be shot if you made more than one pass at WOT and the directs were slipping that much. The car would go into neutral every time it shifted into 3rd if they were that shot.