bbccamaro

Ran @ the track this weekend and starting to get frustrated. here is what I have...

383 pump gas motor 10.3:1

dart iron eagle heads 2.05 intake valves 215 cc runners
speed demon 750 mechanical secondaries
lunati vodoo solid flat tappet 249/257@ .050 lift .540/.560 lift
harland sharp roller rockers 1.5
vic jr. intake
summit billet hei and digital multi spark box
hooker super comps with 3in. true dual & x pipe into bullets dumped at the rear end
450-500 hp estimate

Trans
turbo 400 w/ trans go kit
tci super street fighter

Rear
9in. locker w/ 4.11 gears
mickey thompson drag radials 275/60/15
all tubular control arms and torque arm
12 gallon fuel cell with barry grant 220 gph fuel pump
half in. line ran all the way to the regulator no where near the exhaust
turning 6000 rpm at the stripe

times:
1.77 60'
5.19 330'
8.03 1/8th
87.16 mph
10.47 1000'
12.52 1/4
109.34 mph
car weighs 3500 lbs. and feels like it is pulling hard all the way down the track. It doesn't feel like it is spinning. Could this be a converter slip problem? any help would be greatly appreciated.

AlkyIROC

From your provided numbers, converter slip calculates to 10.12%. Not bad, but not great. Anything under 10% is considered good and under 5% is really good.

You could try a tighter converter, shorter tires or swap the 4.11 to 4.30 or 4.56 gears to drop the converter slip down. 6000 though the traps seems a little low. That camshaft probably has an RPM range up to 7000.

What's the converter's rated stall speed? What's the advertised duration of the camshaft? What altitude or density altitude are you racing at?

bbccamaro

my stall speed is rated @ 3500. not sure, I will have to check on the advertised duration. cam is part no. lunati 60142. No idea on altitude i'm in iowa. thanks

AlkyIROC

60142 camshaft has an rpm range of 2800-7000. Your 3500 stall is slightly high for street/strip and slightly low for full race. Without a transbrake, you'll never know the true stall speed of the converter so just stick with it. You're crossing the finish line well below the peak power of the camshaft so you definitely need a deeper gear as I previously mentioned. 4.30 or 4.56 should work much better. You need to get the engine rpm up into the powerband quicker so it can make use of the high rpm power better. You want to cross the finish line at or just after the shift point. Since that cam makes power to 7000 rpm, that roughly where you should be shifting.

I run 4.86 gears and have a calculated converter slip of less than 4%. I tried dropping down to 4.57 gears for a couple of races but didn't like how the car was responding. The converter slip with the 4.57 gears was around 12% so I went back to 4.86 gears and love them. I'd try some 5.00 gears but feel I would run out of rpm before running out of track. If I was racing at a lower altitude, the 4.57 gears might be better for me.

Gumby

only info I can add is I know allot of guys who have gone thorough the gamibt if TC brands and the TCI ones are usually junk just because they are uni built off the shelf units. To build one proper for a car you needs the cars info first.

A proper built TC by a good company will want the full engine details, trans, rear end and a dyno sheet before they even build it.

Spend to money to get one done right and you'll be happier in the end over uni built units.


http://www.coanracing.com
http://www.accperformance.com
http://www.transmission-specialties.com

bbccamaro

thanks gumby, I was told by my local speed shop to start with a good quality converter also. I hope to be spraying in a year or so and they said I would end up compounding my problem by just doing a gear change. I would be happy running 12.0's-12.2's on motor then see what happens on spray. I just want to get everything squared away before I start changing big things like gear ratio's. I also think a high end converter would give me piece of mind on the spray. What do you think would be stall speed? The car sees limited street time. Thanks

Gumby

It would be a good start, and to be honest you should be asking who ever is gonna build it, they will know more about what stall works best with your combo and plans, just cause they build so many, they will have lots of data to back things up.


Id say Coan is the best or has the best rep or word out mouth and they charge as such, but id talk to em anyways.

TS has a good rep

I Got a ACC and would buy again n hopful soon, when I had my Th350 built I went shy, but as told many times, a well built TC can still do street.
But I only went with a 2200 12in, now I want a 25-2800 10in

AlkyIROC

With torque converters, you really do get what you pay for. My race converter is worth around $1300. An inexpensive converter usually means there's nothing special inside it. Normally stock components with some slight tweaking.

I run a TCS converter made in Langley BC. http://www.tcsproducts.com/