Turbo 400 percentage loss or gain - Chevelle Tech
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post #1 of 19 (permalink) Old Nov 22nd, 19, 11:31 AM Thread Starter
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Gary
 
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Turbo 400 percentage loss or gain

Since racing this year is over, starting to think of new ways to go faster.. I was wondering if any of you have replaced the steel direct drum in a th400 and replaced it with a aluminum one, and gained any ET ? The stock drum is alot of rotational mass... I know they are pricey and not sure I'm going to do that but I do have a extra th400 laying around.. My car has already exceeded my expectations.. Now I want to see how fast I can with what I have to work with, without changeing anything major in the engine.. thanks Gary

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post #2 of 19 (permalink) Old Nov 22nd, 19, 12:50 PM
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Re: Turbo 400 percentage loss or gain

I have an NHRA person that hast tested turbo 400's, 350's, P/G, and a metric 200, all were pretty close except the metric 200 was a tenth and 1.2 mph faster. This guy is a widely known guy in stock and super stock and I went to High School with him, was at the top of his class and can run so far under the index he has to slow the car down. If anyone were to know he would. My own personal feeling is if you are running any kind of BB engine with a lot of torque the turbo 400 for me is the way to go. Mine went 24 years before I needed a rebuild and it still looked great inside, some of the clutches still had the part number on the disc faces.
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post #3 of 19 (permalink) Old Nov 22nd, 19, 1:07 PM
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Re: Turbo 400 percentage loss or gain

I know it has nothing to do with your question, but back in my dirt car oval track days, we reduced drive train drag. REM gears were done to the R&P, also to the quick change gears, which I know you don't have, but every gear. I had the 2 speed trans rebuilt, and the 2 gears that were engaged in high gear, I had them REM. You can look at low drag for your wheel bearings, wheel seals. What weight oils in your rear end and trans. Take a look at your brakes, and how much drag that cause, maybe can do something about that. On our dirt cars, the rotors are turned to be not straight, so when you let off the brake, the high spot on the rotor kicks the pads off the rotors first time around, then ur off the pads down the straightaways. Just some things to think about. Guy can get pretty creative when you think long enough. Not really one big thing, but lots of little things add up. I heard 20hp gain just from rear end gears REM and wheel bearings, but I never did any testing to verify that. Good luck!!
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post #4 of 19 (permalink) Old Nov 22nd, 19, 1:29 PM
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Re: Turbo 400 percentage loss or gain

I have two TH400's for my car. One has a 2.10 first gear straight cut gear set with an aluminum direct drum, the other is a stock helical 2.48 with a steel direct drum.

The 2.10 with the aluminum is slightly faster, a few hundredths, which is very minor.

I'll also note that with the 2.48 trans I have to remove additional timing in the launch ramp to stop the car from doing wheelstands with the additional gearing. So that reduction in power sorta levels out the 2.48 vs 2.10 gearing.


Keep in mind that aluminum drums can wear, mine is on it's last leg, the steel plates tear up the lugs inside the drum. Next time I go through the trans I will replace it with a billet steel drum for longevity.
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post #5 of 19 (permalink) Old Nov 22nd, 19, 2:00 PM
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Re: Turbo 400 percentage loss or gain

Quote:
Originally Posted by 68Chevele View Post
I have an NHRA person that hast tested turbo 400's, 350's, P/G, and a metric 200, all were pretty close except the metric 200 was a tenth and 1.2 mph faster. This guy is a widely known guy in stock and super stock and I went to High School with him, was at the top of his class and can run so far under the index he has to slow the car down. If anyone were to know he would. My own personal feeling is if you are running any kind of BB engine with a lot of torque the turbo 400 for me is the way to go. Mine went 24 years before I needed a rebuild and it still looked great inside, some of the clutches still had the part number on the disc faces.
He's not debating what trans to use, just what material to use in the direct drum of a TH400.

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post #6 of 19 (permalink) Old Nov 22nd, 19, 4:55 PM
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Re: Turbo 400 percentage loss or gain

Yeah Rick, wheeling out to the 330' and still running low 8's is pretty cool!
That must really suck being able to do that!

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post #7 of 19 (permalink) Old Nov 22nd, 19, 5:07 PM
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Re: Turbo 400 percentage loss or gain

Like Rick mentioned I also looked into trans parts and I kinda felt the cost and reliability wasnít worth the gain. My trans was too reliable to mess with so I never did it.
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post #8 of 19 (permalink) Old Nov 22nd, 19, 7:25 PM
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Re: Turbo 400 percentage loss or gain

Quote:
Originally Posted by Calculated Risk View Post
He's not debating what trans to use, just what material to use in the direct drum of a TH400.
Oh sorry, if that's the case look into John Kilgore's stuff. He makes lightend internal drums that won't break the bank.
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post #9 of 19 (permalink) Old Nov 22nd, 19, 8:51 PM
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Re: Turbo 400 percentage loss or gain

Won't break the bank? Have a friend that runs Kilgore 400's. Gonna have to really step up to be able to afford one of those.

But it's true, they do have very low mass internals.
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post #10 of 19 (permalink) Old Nov 22nd, 19, 10:21 PM
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Re: Turbo 400 percentage loss or gain

Quote:
Originally Posted by dyno jonn View Post
Won't break the bank? Have a friend that runs Kilgore 400's. Gonna have to really step up to be able to afford one of those.

But it's true, they do have very low mass internals.
Last time I checked Kilgore's light weight drums were cheaper than the Billet aluminum ones.
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post #11 of 19 (permalink) Old Nov 22nd, 19, 11:50 PM
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Re: Turbo 400 percentage loss or gain

All I know is he has one of Kilgores trannys that has the sheet metal internals and odd ball gear ratios. Can't really comment on his separate parts prices for drums and such.

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post #12 of 19 (permalink) Old Nov 23rd, 19, 6:31 AM
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Re: Turbo 400 percentage loss or gain

Quote:
Originally Posted by TAG55 View Post
Since racing this year is over, starting to think of new ways to go faster.. I was wondering if any of you have replaced the steel direct drum in a th400 and replaced it with a aluminum one, and gained any ET ? The stock drum is alot of rotational mass... I know they are pricey and not sure I'm going to do that but I do have a extra th400 laying around.. My car has already exceeded my expectations.. Now I want to see how fast I can with what I have to work with, without changeing anything major in the engine.. thanks Gary
This is more expensive than the direct drum modification but pretty interesting

ATI Racing Transmissions - TH400 Drag Racing Transmissions

Turbo 400 locker up converter. I have no experience with it but I like the idea

Thanks Joe
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post #13 of 19 (permalink) Old Nov 23rd, 19, 7:22 PM
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Re: Turbo 400 percentage loss or gain

How about going to a built TH350????
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post #14 of 19 (permalink) Old Nov 23rd, 19, 7:29 PM Thread Starter
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Gary
 
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Re: Turbo 400 percentage loss or gain

Quote:
Originally Posted by Calculated Risk View Post
I have two TH400's for my car. One has a 2.10 first gear straight cut gear set with an aluminum direct drum, the other is a stock helical 2.48 with a steel direct drum.

The 2.10 with the aluminum is slightly faster, a few hundredths, which is very minor.

I'll also note that with the 2.48 trans I have to remove additional timing in the launch ramp to stop the car from doing wheelstands with the additional gearing. So that reduction in power sorta levels out the 2.48 vs 2.10 gearing.


Keep in mind that aluminum drums can wear, mine is on it's last leg, the steel plates tear up the lugs inside the drum. Next time I go through the trans I will replace it with a billet steel drum for longevity.
Thanks Rick thats what I was looking for as far as real world testing.. As much as I 've seen your car in videos and running dragweek you should know if there are any gains.. Looks like cost vs. gains to be had is not worth it.. You have and bad Hot rod.. thanks again, Gary

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post #15 of 19 (permalink) Old Nov 24th, 19, 12:20 AM
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Re: Turbo 400 percentage loss or gain

Quote:
Originally Posted by TAG55 View Post
Since racing this year is over, starting to think of new ways to go faster.. I was wondering if any of you have replaced the steel direct drum in a th400 and replaced it with a aluminum one, and gained any ET ? The stock drum is alot of rotational mass... I know they are pricey and not sure I'm going to do that but I do have a extra th400 laying around.. My car has already exceeded my expectations.. Now I want to see how fast I can with what I have to work with, without changeing anything major in the engine.. thanks Gary
I can tell you your on the right track, I've seen a dramatic performance increase with a well built turbo 400, were talking tenths not hundredths, but the price tag was 7500.00.

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