Converter matched??

One of the most critical areas of a automatic race car

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Prostreet1
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Converter matched??

#1 Post by Prostreet1 » Fri Jan 28, 2011 8:48 pm

Wanted to run my set up past you guys to see if we're leaving anything on the table. We run a few Super Pro money races however prefer Super Comp racing. We built a new 598-conventional headed engine last season on Alky, in a hard tail with Diamonds front suspension, 235" dragster. The engine broke in on the dyno at just under 1045hp on Gas with too small of a carb and 986 on alky. I have a dedenber 1.80 glide and 4.10 rear. I'm currently running a 16x33" rear Goodyear.
I will say this car is a bit heavy. It weighed 1770 w/o driver and I weigh 230. I was hoping to see the car run mid 7.50's @ 180+mph. It's best so far is 7.67 @ 176mph. It has an ATI 9" converter.
I do not have a data recorder in the car however I do have a playback tach. I shift the car @ 7400.
My best 60' was 1.096 in Florida last year with PERFECT air and usually pulls a 1.11+
I aslo run a rear wing and it's not a CF mono, so we have some weight and downforce here as well. I do have 2 yellow tops which after working closely w/CSR, I will be removing one of these this season.
As far a my 1/8 mile times, we're in the mid 4.80's. On the stop, the car runs out the back door @ 171-172mph.

Just wanted your opinions to see if you think we're right there or need to consider or look at ???

Thanks...

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Marty Chance
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Re: Converter matched??

#2 Post by Marty Chance » Sat Jan 29, 2011 10:36 am

sounds like the combo is pretty close , but to accurately fine tune you need some data such as :
flash at the launch
does it flat line or dip back down after the launch
rpm drop on the shift
recovery after the shift

there are some inexpensive ways to get data , the msd digital ignition or RPM data loggers . The MSD you can find anywhere and this is a good thing to have as it allows you to set a timeing curve for launching. The RPM data logger you can find on my web site www.racingconverters.com and this is a good thing to have as the basic system for $588 can be updated one piece at a time until you have a full blown pro-stock data logger. (basic has engine rpm, driveshaft and battery)
Neal Chance Racing Converters
Home of the World's Fastest Automatic Doorslammers!
www.racingconverters.com

Prostreet1
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Location: Gahanna, Ohio
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Re: Converter matched??

#3 Post by Prostreet1 » Sat Jan 29, 2011 2:30 pm

Appreciate the reply... I went ahead and video tapped the playback tach in both 1.1 and 1.3 scale. Hope this helps with the info. you ask about. The digital clock is hard to read. It's reading in .2 incrementals.
I'm hoping I can get this to load here...not sure
Please let me know after you've had a chance to view this and thanks

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Marty Chance
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Re: Converter matched??

#4 Post by Marty Chance » Mon Jan 31, 2011 7:48 am

the converter is working good. it flashed 6200 and dropped to 6400 on the shift. You could try a lighter viscosity trans fluid to raise the flash stalls about 200 rpm to see if it likes that(redline light weight atf 800-624-7958 ask for kelly or camron) or you could go with the rear end gear one step lower (if 4.10 now -try 4.30)
Neal Chance Racing Converters
Home of the World's Fastest Automatic Doorslammers!
www.racingconverters.com

Prostreet1
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Re: Converter matched??

#5 Post by Prostreet1 » Mon Jan 31, 2011 5:35 pm

Appreciate your honesty Marty...
As far as changing/trying the 4.30 gear, what changes do you think it will make to our set-up? A little quicker on the 60', maybe a little on ET and down slightly on mph?
Maybe I should be shifting at 7400. Thought I was however the playback says different.
As far as numbers from our dyno session as these may or may not help:
Peak hp was 991.6 @ 7200
Peak torque was 838.5 @ 5400...These were on ALKY
On gas it peaked HP @ 7400 and peaked torque @ 5100

Thanks again...

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Marty Chance
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Re: Converter matched??

#6 Post by Marty Chance » Tue Feb 01, 2011 7:50 am

are you racing on gas or alky?
the gear change will make the car react a little faster , 60' a little better , recover the shift faster . in other word it will connect all the good accelleration points and make the vehicle accelerate faster with the same amount of power. You may not loose any mph either as mph is more a product of HP than gear ratio, in fact it is possible to slighly gain mph IF the car accellerates better. But it is all theory until it gets to the track and we see exactly how your car reacts to the changes. Keep me posted as to how the car works with the gear change.
Neal Chance Racing Converters
Home of the World's Fastest Automatic Doorslammers!
www.racingconverters.com

Prostreet1
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Re: Converter matched??

#7 Post by Prostreet1 » Tue Feb 01, 2011 10:34 am

We are on Alcohol.
Will consider the gear change, possibly just go ahead and build a 4.30 center section for an easy swap.
Thanks for the input and I will let you know how it reacts...Probably after Indy's Divisional in April.

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