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Old 07-11-2004, 01:18 PM
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Question Converter Efficiency

Posted this in the Dyno section but not getting much response.

Here's the deal, got my car dynoed for the first time the other day, I was very pleased with the locked numbers, but unlocked there was a much bigger loss than I was expecting.

Locked: 345 rwhp / 353 rwtq
Unlocked: 323 rwhp / 339 rwtq

323/345 = 93, is this my efficiency, or is it on the tq side (works out to 96)? I just thought the 22 hp drop was pretty big.

Thanks,
Craig
Old 07-11-2004, 02:19 PM
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Well honestly compared to mine 327hp locked and 283 unlocked! Im having my converter redone after that! Jason at MTI ran it on the dyno a few times comparing both. Looks like a bum converter so having Precision go ahead and restall it and fix it. He said from what I understand looks like you should loose around 20hp give or take just depends on how loose the converter is or efficeint it is. Maybe someone will correct me and Ill learn something.
Old 07-11-2004, 03:13 PM
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93.6% is what I would expect to see.

John
Old 07-12-2004, 11:10 AM
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22 Hp is a pretty sizable loss for a 3500 stall on bolt-ons. Is it a tight feeling converter? They tend to be lower efficency.

I assume these were Back-to-back dyno runs.

I lost 13 hp with YTP 4200.
Old 07-12-2004, 02:04 PM
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Yeah, these were on back to back runs. It's a TCI SSF converter. I can't really compare how tight it is to any other aftermarket converter because it's the only one I've had. Maybe I'll contact TCI.

Craig
Old 07-12-2004, 03:02 PM
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Well, I spoke with Kevin at TCI. He said it sounds like the converter is slipping a little bit more than it should be. He said they would look at it if I wanted, but 5-10 hp isn't worth dropping the trans again to me. He also said it will get more efficient the higher the rpms go, so after a new cam it should be better. FYI unlocked/locked does not equal efficiency. Kevin said it is a pretty good estimation, but not the right way to figure it.
Old 07-12-2004, 03:49 PM
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I wouldn't bother either for 5 hp.

The most common ways to look at efficency are locked/unlocked and rpm slippage (engine rpm vs output shaft rpm). They are pretty measurable for the common man.

I like locked to unlocked because I'm more interested in power to the rear wheels.

BTW, What did Kevin suggest?
Old 07-12-2004, 04:21 PM
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Kevins only suggestion would be to send it to them so they could check some internal tolerances. Not worth it to me.
Old 07-12-2004, 09:10 PM
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My bad, I meant what did Kevin suggest for how to measure efficency?
Old 07-12-2004, 09:30 PM
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Originally Posted by calongo_SS
Well, I spoke with Kevin at TCI. He said it sounds like the converter is slipping a little bit more than it should be. He said they would look at it if I wanted, but 5-10 hp isn't worth dropping the trans again to me. He also said it will get more efficient the higher the rpms go, so after a new cam it should be better. FYI unlocked/locked does not equal efficiency. Kevin said it is a pretty good estimation, but not the right way to figure it.
What efficiency numbers did Kevin say to expect?
Old 07-12-2004, 10:27 PM
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Originally Posted by Ragtop 99
My bad, I meant what did Kevin suggest for how to measure efficency?
He didn't give me any specifics, he just said that's not the way to do it. Kevin made it sound like 95% - 97% is normal. He said I'm just out on the low end. I think he was using the number (93.5) that I gave him when he said this, so that method must be pretty damn close.
Old 07-13-2004, 11:25 AM
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23 RWHP is what my TCI 3500 lost unlocked. That didn't bother me at all considering that it trapped 113.5 MPH with an internally stock engine at 3550 lbs with stock gears. I wouldn't worry about it if it works well at the track.
Old 07-13-2004, 04:27 PM
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Yup, need to get to the track. That's the real test. Just too far of a drive to a decent track



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