From my calculations my converter is killing it

[22lbChevelle]

Ok so I went to the track in july and as Im waiting to finish my paint job Im sitting and thinking about makin the car faster.

Heres what my best was in 100 degree weather first time out.

60ft - 2.029
330 - 5.362
1/8 - 8.160
MPH - 87.32
1/4 - 12.682
MPH - 107.75

Her is a powerlogger image

So given 2.73 gears, 27in tires, 4400 top engine rev, I come up with


(4400 engrev/min)(84.82 in/tirerev)(60 min/hr)(ft/12 in)(mi/5280 ft)(1 tirerev/2.73 engrev)=129.5MPH

And since my 1/4mile speed was only 107.7mph that makes my converter slip a whopping (129.5MPH)/(107.75)-1= 0.201=20.1% Am i missing something here? Looks like it.

 

[Boost231]

you need to look at the time slip. look at when the vehicle starts moving and use your et from there and add. then find that on the data log and use that # not when you chopped the throttle. also what tires are you running. i know the MT 275/60s are 28 inches tall.

whats the trans ratio in 3rd? not sure what trans your using.

also is that locked or not?

why is your TPS wavey?
what converter

 

[22lbChevelle]

I killed the throttle right at the end so the rpm is indicative of the end speed.

Also I did use 275/60r15s

End of the track was in 3rd gear unlocked

TPS is wavey cause Im so scared of knock when heading down the track

converter is stock, refurbished by the guy my tranny rebuilder uses.

 

[Boost231]

time to call dusty and have hin set you up with a converter that will have low slip # and also get you out of the hole.

also shift points seem alittle low

what trans and who built it.

 

[SCOOBY DOO]

Punching in all your numbers into the TCI calculator I get a slip percentage of 22%.

 

[WSLN 6]

To get a more accurate run I would up the fuel 1 psi and get that tps flatlined at 4.2+.
You may have fueling changes if you are out of the power enrichment tables etc. if your tps drops too low. Just a thought. And.......go

 

[bison]

i know the MT 275/60s are 28 inches tall.

They arent. 27.3" measured.

 

[22lbChevelle]

Trans was done by Dave Splett in Lynnwood washington. He has built a couple 200r4s for the 9sec buicks around here.

20% is pretty bad right? What are most of you shooting for?

 

[Onalky87]

They arent. 27.3" measured.

Interesteding. Is it with the recommended air pressure or 18psi set up for the track?

Makes me wonder if they got 28 Bc there was 25psi in them or something and not mounted on the car

 

[Boost231]

On summits site says 28. I never messure mine. Also as far as what slip you want... less then 5%

 

[22lbChevelle]

Less than 5%? Holy crap. Im wondering if it purely torque converter slip or if it is some gear slip too.

 

[bison]

Interesteding. Is it with the recommended air pressure or 18psi set up for the track?

Makes me wonder if they got 28 Bc there was 25psi in them or something and not mounted on the car

Pressure didnt matter. I never tested below 17psi. I measured on the car just like i do with every tire i measure. I have about 3.5% slip in my black car at 143mph. About 5% with my blue car at 125mph and 2.5% at 130mph. Both have similar PTC 9.5" converters.

 

[Boost231]

hard to say, at your power level try locking the converter as soon as it hits 3rd and see what the slip is then

 

[bison]

Less than 5%? Holy crap. Im wondering if it purely torque converter slip or if it is some gear slip too.

If it was the trans the fluid would be chit after one pass.

 

[22lbChevelle]

Damn, I change the trans fluid about every 5k and it has about a 1/8th inch of clutch material at the bottom of the pan every time. I boost the car every time I drive it though, it is not babied. Is this an excessive amount of clutch material? The tranny is great on the 1-2, a little less firm on the 2-3 to the point where you can tell it isnt gunna want to take too much more power.

 

[GNVYUS 1]

The stock 12" converter isn't worth rebuilding IMO to put back into rebuilt transmissions that are intended to be used for faster cars. The weight of the PTC 9.5" alone is probably worth a tenth right there over the stocker, now take into account the custom stator and improved K Factor.

Not sure what it shifts at but 5500 is pretty normal with some governor work, higher for those of us with the PTC and the Monte Carlo KC valve body.

 

[83ttypecooled]

Hi,
Some of that slip is in the trans. Lock it up and you will see how much. You have a dirty pan on service? That's slip.Did your builder put in hardened parts? Or did you run out of money, like I have? My modest engine has overpowered my trans,and I just baby it. Can't afford the solution.The 200 r4 always was a weak sister,anyway.... Good luck with your issue.

 

[22lbChevelle]

I havent raced it much since the last fluid change, which was a conversion to type F. No hardened parts were used, I was 19 years old in 2006 when he rebuilt it for me so I have no ill feelings. It still works fine.

A guy 10 minutes away has a bop 400 for sale that was rebuilt and never used for $300 so I thinkI may head that way next week.