fasteddi

iTrader: (2)

I have a 700r4 with a few mods done to it. I bracket race it quite a bit. 3.73 rear end gears on 28x10 slicks.

What I noticed on a data log was that my RPM Vs the Tire diameter Vs the MPH was a lot higher then i thought i would be (the ratio between the group)

OR is this normal from the tq converter slipping??

Trap was 116Mph@6300rpm

Does anyone have a good lead on a calculator that will tell me a rough estimate on what rpm i should be turning vs mph and tire diameter in 3rd gear on a 700r?

Thanks for any input. I also attached that datalog that can be looked at on excel.

Night rider327

iTrader: (13)

5192 rpm w/o converter slip factored in

3rd gear is 1.00

I come up with your converter slip at 14.88% Could be more or less as I don't know your tire's true roll out, nor does it count for tire growth at the big end of track.

Is your trans/converter lock up or non lock up?

For stock and cheaper made off the shelf non lockup converters 8-12% slip is common avg. For custom made race converters 5-7% slip is the norm.

I have seen some aftermarket converters with 15-17% slip and that's just way too much

fasteddi

iTrader: (2)

Yea it's a lockup converter.

I think it's just time to look into a better converter. Too bad it's gotta be a custom one. I one makes them for the narrow 700r4 that's in my v6.

cosmick

I've had a converter that slipped that much, but there's more to this than calculating at 116 MPH. See, the dragstrip gives your speed between the 1/4-mile mark, and a point before you finish the distance. Your actual MPH right on the final stripe is more like 119. Then what's the actual measured rollout of those 28" tires? Measure that, then divide that by 3.1416 before trying to calculate what your RPM should be.
There's no reason you can't get the same stall speed with less than half that much slippage from a good converter. A thousand RPM of slippage is a very poor converter indeed.
GM lockup converters aren't made to survive lockup at WOT, even at 200 HP in a 3000# car. You have to waste a grand on a specialty converter if you want WOT lockup.

fasteddi

iTrader: (2)

The 116mph and 6300 rpm was from a datalog on tunerpro at the track.

I will have to find the roll out on the 28 inch tires.

I talked to freakshow about a converter. May go that route. The stall I have is basically a high stalled stock convertee which I know is a poor converter.

Anyone have opinions about freakshow converters?

It doesn't have to be a lockup converter. But what are the cons of a non lock up converter for a car I drive on the street a bit?