Possable Converter issue

One of the most critical areas of a automatic race car

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BBCPWR
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Joined: Fri Jan 10, 2014 1:23 am

Possable Converter issue

#1 Post by BBCPWR » Sat Jan 11, 2014 11:54 pm

Got a altered weighing 1670lbs. Has a 358ci 15deg sbc making just on 800hp. Makes power to 9100. 495ft lbs at 8350rpm 4.58 rear gear with a 32in tall tyre. powerglide 1.7 first gear. Ive had to conv in this car. I had a converter in the car that was dropping to 7500rpm on the shift and it seemed way to tight. Ideally needing a 8500 conv. But with the first conv after the 1-2 shift would rev up to 9400rpm and drop to 7500 rpm pretty much straight away the rev up to 8300 rpm over the finish line. !/8th mile.
Converter 2. Borrowed a brand new conv off a friend that he has for a spare behind a very similar engine. This time rev it up to 9400 on the shift but once it shifts it drops to 8150rpm. Which is better but here is the strange bit. At 2.6 sec into the run I shift at 9400 but it takes till 3.8sec into the run before it gets down to 8150rpm. So after I shift it takes 1.2 sec before it gradually drops down to the converter then starts to slowly pick up rpm. Pulled the auto out and had it checked. It was perfect. What else can do this. Im only new to looking at N/a converter stuff on loggers but it just seems to me it take 1.2sec for the auto/conv to catch up and it slowly pulls the engine down.
Any other ideas out there. Maybe the engine isn't that health not sure but it seems strange that the tighter converter didn't have that issue.
Any help would be good
Thanks

bracketchev1221
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Location: Mountville PA

Re: Possable Converter issue

#2 Post by bracketchev1221 » Mon Jan 13, 2014 6:56 am

I would check the data logger pickup point. That would be highly noticeable at the gear change if it took 1.2 seconds for rpm to drop that far. I know in my car only going 9.0's things look like slow motion. So 1.2 seconds would be an eternity to me for a shift.

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Marty Chance
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Re: Possable Converter issue

#3 Post by Marty Chance » Mon Jan 13, 2014 1:36 pm

the converter you borrowed was it a 7" ? sometimes a converter design can have too much slippage and it takes some time for the converter to catch up, so in simpler terms is sounds like the converter has a lot of slippage right there and it takes 1.2 seconds to recover. I could tell you more if i seen the data log.
We have some specific designs for high stall (8000+) with very high flow so it transfers power better. (like our hot street, pro stock and N/A 10.5 class cars run)
If you call me we can get much more specific
Marty Chance 316-542-9869
Neal Chance Racing Converters
Home of the World's Fastest Automatic Doorslammers!
www.racingconverters.com

BBCPWR
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Joined: Fri Jan 10, 2014 1:23 am

Re: Possable Converter issue

#4 Post by BBCPWR » Mon Jan 13, 2014 3:04 pm

Hey marty can i please send me racepak file to you?
Thanks for the reply too

BBCPWR
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Joined: Fri Jan 10, 2014 1:23 am

Re: Possable Converter issue

#5 Post by BBCPWR » Mon Jan 13, 2014 3:05 pm

Yes it was a 7inch

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Marty Chance
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Re: Possable Converter issue

#6 Post by Marty Chance » Mon Jan 13, 2014 5:41 pm

converter being a 7" is why you see the 1.2 seconds to fully drop on the shift. There is a lot more to it, more than what we can discuss on line. If you call me i will be happy to give you all the info you need, just remind me you are the one from this thread.
Marty 316-542-9869
Neal Chance Racing Converters
Home of the World's Fastest Automatic Doorslammers!
www.racingconverters.com

BBCPWR
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Joined: Fri Jan 10, 2014 1:23 am

Re: Possable Converter issue

#7 Post by BBCPWR » Wed Jan 15, 2014 5:23 am

Thanks Marty, Im in Australia so Ive got to set a day when I can wake up very early in the morning to call.
Don't all the comp racers use 7in converters. Most of the fast guys use 7inch conv with success.

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Marty Chance
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Re: Possable Converter issue

#8 Post by Marty Chance » Wed Jan 15, 2014 9:35 am

7" is old school , we have much better technology that stalls higher, drops less on shift and locks up better out the back. In short it is a much better power transfer than the 7".
Neal Chance Racing Converters
Home of the World's Fastest Automatic Doorslammers!
www.racingconverters.com

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