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Old 04-19-2011, 04:51 AM
 
Location: Earth
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This one's for anyone who's ever messed with a higher than stock torque converter. I totally understand the main reason for running a high performance torque converter is when you have a camshaft or a turbo that is bigger than stock, which requires it.

Let's say you're going from a 12 inch converter to a 10 inch or even a 9.5 inch. As I understand going to a smaller sized converter than the stock one (12 inches in my case) usually means going from a heavier converter to a lighter converter.

As a result you have less spinning mass. My question is how much hp/tq can you free up by switching from the heavier 12 inch converter to the smaller converter?
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Old 04-19-2011, 05:41 AM
 
Location: U.S.A.
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The dimensions/specs. are model dependent so hard to say. If you really want to get into it I would suggest looking at some of these:

http://en.wikipedia.org/wiki/List_of_moments_of_inertia

For sake of argument and confusion I would consider the TC as a rigid body even though it is not.

Full article: http://en.wikipedia.org/wiki/Moment_of_inertia
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Old 04-19-2011, 06:23 AM
 
Location: South Jersey
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The idea behind a smaller converter is not to save spinning weight but to raise the stall speed of the converter. Most 'big' cams and big turbos etc have no low end or make hp/torque starting at a higher rpm. Raising the stall speed of the converter allows you to get into the torque curve on a launch against the brakes (or trans brake) sooner allowing a faster launch..
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Old 04-19-2011, 07:14 AM
PDD
 
Location: The Sand Hills of NC
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Quote:
Originally Posted by frankgn87 View Post
The idea behind a smaller converter is not to save spinning weight but to raise the stall speed of the converter. Most 'big' cams and big turbos etc have no low end or make hp/torque starting at a higher rpm. Raising the stall speed of the converter allows you to get into the torque curve on a launch against the brakes (or trans brake) sooner allowing a faster launch..
Great explanation Frank, plain and simple without the need for three paragraphs of technical BS
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Old 04-19-2011, 07:33 AM
 
14,777 posts, read 34,490,118 times
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Quote:
Originally Posted by frankgn87 View Post
The idea behind a smaller converter is not to save spinning weight but to raise the stall speed of the converter. Most 'big' cams and big turbos etc have no low end or make hp/torque starting at a higher rpm. Raising the stall speed of the converter allows you to get into the torque curve on a launch against the brakes (or trans brake) sooner allowing a faster launch..
Quote:
Originally Posted by PDD View Post
Great explanation Frank, plain and simple without the need for three paragraphs of technical BS
Agreed, simple and to the point....now onto the exact technical details of how it works...lol.
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Old 04-19-2011, 11:00 AM
 
Location: Earth
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Quote:
Originally Posted by frankgn87 View Post
The idea behind a smaller converter is not to save spinning weight but to raise the stall speed of the converter. Most 'big' cams and big turbos etc have no low end or make hp/torque starting at a higher rpm. Raising the stall speed of the converter allows you to get into the torque curve on a launch against the brakes (or trans brake) sooner allowing a faster launch..
True Frank, and seeing you're a former Buick Grand National guy, you also probably know that the stock converter used in the GN was the D5 that stalled at something like 2200 rpms..? And that some companies can "restall" the otherwise stock D5 converter...or you could go with an aftermarket converter which is smaller and lighter than the D5 converter. Which I'm sure probably takes less effort for the engine to spin as opposed to the stocker.

FWIW in my situation, yes I actually need a higher than stock converter since my turbo is an aftermarket PTE that's good up to 580-600 hp and the camshaft is a Poston's grind with a 212/206 @ .050 duration, yet there's still a presumably stock D5 converter between the turbo V6 and the TH200-4R. Unfortunatley at the track, my best 60 ft is a 2.00 and it's not spinning off the line. And that was footbrake launching with 7-8 psi.
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Old 04-19-2011, 11:18 AM
 
Location: South Jersey
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yup deez.. I had a custom made 2800 rpm stall converter in my GN. a 2.0 and NOT spinning?? Wow, you are sure leaving a lot on the table. You need a converter in your car and 1.6's are yours..
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Old 04-19-2011, 04:15 PM
 
Location: U.S.A.
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Sorry. I thought the OP was specifically asking about the correlation between power consumption and rotating masses, not the general function of a TC. Guess not.
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Old 04-19-2011, 05:13 PM
 
Location: Earth
4,227 posts, read 20,280,133 times
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Quote:
Originally Posted by frankgn87 View Post
yup deez.. I had a custom made 2800 rpm stall converter in my GN. a 2.0 and NOT spinning?? Wow, you are sure leaving a lot on the table. You need a converter in your car and 1.6's are yours..
Hey Frank who did you have build your converter?

Also what turbo and cam did your car have?

Yeah that's 2.0 and no spin, a guy did say he thought I might be bogging. I do run a progressive alky system that turns on at 7 psi. So it could be possible that I'm loading up the engine on launch. But then again on my car you stomp the pedal from a dead stop and it takes off out of the hole like a carbed V6 Regal would....until 10 feet into it when the turbo begins to spool up and then the tires shriek before hitting 2nd. They don't go up in smoke at all.

However someone on turbobuick.com claims they recently ran a 10.94 in the 1/4 on a TA-49 turbo and a stock D5 converter. But I think he launched at 20 psi of boost, probably using the ebrake.
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Old 04-19-2011, 06:25 PM
 
Location: South Jersey
7,780 posts, read 17,779,267 times
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Yea i have known some guys who have ran 10's on a 49 too. Its pretty hard and like you said on the e brake.. tough on the car

I had the converter made by Pats converters in Folsome pa. Here is his website. Makes good converters. I had a model # 1003XHD in my car. 10" lock up. I could punch mine from an idle and within a split second the tires would be spinning. (275 drag radials). Had a TA52 turbo from precision and a a comp cams cam(I do not remember the specs but it was mild) My car was a beast.. My wife almost crashed it one day when the boost hit and she almost did a 180 on rt 73. Never drove it again

Welcome to Pat's Performance Converters!
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