converter acting strange

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hjallle123
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converter acting strange

Post by hjallle123 » Mon May 07, 2018 2:26 pm

Hi

Drove my race car this weekend

the car wieght is 2462 lbs
406 cui sbc 18 degree engine dyno to 768 hp at 7500 rpm and torque 585 at 6200 rpm

the car is a 7.50 fulltube chassie
powerglide with 9 inch coan converter from 1996 ( coan say its a 7 inch converter according to part nr) but its 9.5 inch in diameter
have askd coan on mail 4 times why its 9.5 inch in diameter and they say its a 7 inch , but they dont awnser !!
can you build a converter with 7 inch internal parts in a 9.5 inch case and if they do that.. why??

my rear gear are 5.67 ( only race 1/8 track)

powerglide 1.76

best et this weekend was 5.74 sec
best topspeed was 122.41 mph
best 60 fot was 1.318 !!

topspeed is god but et and 60 fot are bad i think!!
the converter stall with transbrake is 6700 rpm ( is this high with a 9 inch converter, can you make a 9 inch go 6700 rpm on stall?)
start with transbrake was best at 6400 rpm
shift 8000 rpm
8200 rpm at 1/8 track

can the converter slipp on launch and lock upp better on the way up in rpm
or are my rear gear wrong ???
the car is na ( no power adder)

somewone here that can give me a hint of whats wrong ??

thanks

fdicrasto
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Re: converter acting strange

Post by fdicrasto » Mon May 07, 2018 11:11 pm

Basically you are correct about your 60' and et. They are way off. So you have a 22 year old convertor. Why? A 9" can be loose enough to yield 6000+ stall speeds but you would be better off with an 8" convertor to pull 6000-7000 stall speeds. I hope your tires are newer than your convertor. Maybe that old of a convertor part number may be obsolete. Why not ship it back to Coan and let them look at it and freshen it to what you want if that is possible, otherwise bite the bullet and buy something new and up to date. Then you can look to why your car is 3-4 tenths off the mark.

hjallle123
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Re: converter acting strange

Post by hjallle123 » Tue May 08, 2018 4:05 pm

got email from coan today

converter are not 22 years old its 24 years old !!!! :o

and its a 9 inch converter for a 440 engine ,its all they have on this converter

so i will order a new converter :)

gowest
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Re: converter acting strange

Post by gowest » Tue May 08, 2018 5:06 pm

The stated diameter of a converter is what the turbine measures. So the end user has to guess a bit from the OD of the impeller housing.

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