Convertor help

Mike Pearson · 08-09-2023, 04:17 PM

Quote:

Originally Posted by hbr509

I don,t know , I only know shift is 6500 and so had to be somewhere around 5500. I called PTC and gave them the number stamped on convertor to duplicate but what they sent was to loose ,as soon as i left the starting line it was in high gear

You cant have a converter that stalls 6300 and shift at 6500. you said your engine made max power at 7500. That is where your shift rpm should be and that would match up pretty well with the 6300 stall speed. When you ordered the new converters did you tell them the engine max power was 7500?

L.Fite · 08-09-2023, 04:34 PM

So...
I know nothing...
But stall should be around peak torque and shift at or above peak H.P.
I would send a dyno sheet to whomever you have build your converter...
They should be able to get you real close...
I always had good luck with Coan, and ATI...
Like I said I know nothing, just my going by my experience...

hbr509 · 08-09-2023, 05:25 PM

Thanks for the replies , The original PTC that blew up was sent to FTI and they said it was not salvageable, My fault for not getting it back , and yes I,m sure it was changed from original specs, I sent FTI, ABRUZZI AND PTC dyno sheet and motor build sheets all convertors where 6200-6400 on racepack also all ran the exact et and mph Great for bracket racing but 10th slow in 60 ft does not wheelie anymore so no rotation . I shifted at 7200 with those convertors , My thoughts are this car was very popular for SS racing and seen alot of them leave harder then what i have . peak torgue is 704@5900 and 804hp @7400

Adger Smith · 08-09-2023, 08:36 PM

6500 is too low to shift.
converter guys all built them for an engine turning 7500+ by looking at the dyno sheet. your 6500 shift makes the RPM fall way below peak TQ. The converter is hanging and can't climb RPM back over peak Tq. If your going to continue to shift at 6500 you need a converter built for the power curve from peak TQ to 6500 on the dyno sheet. Your leaving power and ET on the table.
Shift it at 200 above peak HP on the dyno sheet with the converter you have and look at the ET/MPH.
You need to have a serious conversation with a good converter guy.. not a salesman.

tavirace · 08-11-2023, 07:45 AM

This may not apply but just thought I would share. I raced a stock eliminator Chevelle for years and it suddenly lost all it had, 60ft's, consistent lights,winning rounds were gone. I tried tires,converters, gears, rear suspension,shocks, nothing worked. I was telling a very talented racer my problem and they said, How old are your front springs ? They were Morosos at least 20 years old, I replaced them and everything went back to the way it used to be. If I was chasing something it's the first place I'd go.

Adger Smith · 08-11-2023, 09:47 AM

That last post brought up a memory of a customer problem.
He had a major converter trashing.
Put the same part# and brand converter back in it and it was slow.
Like the OP is experiencing.
Finally found the Stator support tube that presses in the front pump had slipped and restricted a hole or two.
An aftermarket stator support aligned properly brought back his good numbers.
Just food for thought...

hbr509 · 08-14-2023, 06:24 AM

Good thoughts guys but shocks in front are lakewood 90/10 and are fine , also the trans has been changed also I have 2 each time and same results , I bought a new front pump from Abruzzi and input shaft still the same, I went to Bradenton last friday with the PTC tighten 500 rpm according to race pak and same results 1.38v 60ft 6.10 et and no rotation on front , I am pulling motor and sending back to Nesbitt for check and freshen up . This is the only thing I have not done yet . I have changed the distributer,coil,msd box you name it its been changed lol. I,m tired Thanks For your help .will keep posted when the motor comes back .

08-09-2023, 04:34 PM	#2
L.Fite Senior Member Join Date: May 2020 Posts: 519 Likes: 562 Liked 498 Times in 244 Posts	Re: Convertor help So... I know nothing... But stall should be around peak torque and shift at or above peak H.P. I would send a dyno sheet to whomever you have build your converter... They should be able to get you real close... I always had good luck with Coan, and ATI... Like I said I know nothing, just my going by my experience...

08-09-2023, 05:25 PM	#3
hbr509 Junior Member Join Date: Jul 2023 Posts: 4 Likes: 0 Liked 3 Times in 2 Posts	Re: Convertor help Thanks for the replies , The original PTC that blew up was sent to FTI and they said it was not salvageable, My fault for not getting it back , and yes I,m sure it was changed from original specs, I sent FTI, ABRUZZI AND PTC dyno sheet and motor build sheets all convertors where 6200-6400 on racepack also all ran the exact et and mph Great for bracket racing but 10th slow in 60 ft does not wheelie anymore so no rotation . I shifted at 7200 with those convertors , My thoughts are this car was very popular for SS racing and seen alot of them leave harder then what i have . peak torgue is 704@5900 and 804hp @7400

08-09-2023, 08:36 PM	#4
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: Convertor help 6500 is too low to shift. converter guys all built them for an engine turning 7500+ by looking at the dyno sheet. your 6500 shift makes the RPM fall way below peak TQ. The converter is hanging and can't climb RPM back over peak Tq. If your going to continue to shift at 6500 you need a converter built for the power curve from peak TQ to 6500 on the dyno sheet. Your leaving power and ET on the table. Shift it at 200 above peak HP on the dyno sheet with the converter you have and look at the ET/MPH. You need to have a serious conversation with a good converter guy.. not a salesman. __________________ Adger Smith (Former SS) Last edited by Adger Smith; 08-09-2023 at 08:39 PM. Reason: add

08-11-2023, 07:45 AM	#5
tavirace Junior Member Join Date: Oct 2021 Posts: 38 Likes: 7 Liked 22 Times in 14 Posts	Re: Convertor help This may not apply but just thought I would share. I raced a stock eliminator Chevelle for years and it suddenly lost all it had, 60ft's, consistent lights,winning rounds were gone. I tried tires,converters, gears, rear suspension,shocks, nothing worked. I was telling a very talented racer my problem and they said, How old are your front springs ? They were Morosos at least 20 years old, I replaced them and everything went back to the way it used to be. If I was chasing something it's the first place I'd go.

08-11-2023, 09:47 AM	#6
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: Convertor help That last post brought up a memory of a customer problem. He had a major converter trashing. Put the same part# and brand converter back in it and it was slow. Like the OP is experiencing. Finally found the Stator support tube that presses in the front pump had slipped and restricted a hole or two. An aftermarket stator support aligned properly brought back his good numbers. Just food for thought... __________________ Adger Smith (Former SS)

08-14-2023, 06:24 AM	#7
hbr509 Junior Member Join Date: Jul 2023 Posts: 4 Likes: 0 Liked 3 Times in 2 Posts	Re: Convertor help Good thoughts guys but shocks in front are lakewood 90/10 and are fine , also the trans has been changed also I have 2 each time and same results , I bought a new front pump from Abruzzi and input shaft still the same, I went to Bradenton last friday with the PTC tighten 500 rpm according to race pak and same results 1.38v 60ft 6.10 et and no rotation on front , I am pulling motor and sending back to Nesbitt for check and freshen up . This is the only thing I have not done yet . I have changed the distributer,coil,msd box you name it its been changed lol. I,m tired Thanks For your help .will keep posted when the motor comes back .