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Blowing through the converter ?

Posted By: Tig

Blowing through the converter ? - 10/08/22 06:24 PM

Sounds like we are blowing through the converter here, RPM drop is around 600rpm according to the race pack. Stall has increased from 5200 to a tickle over 6000 since we swapped gears from a 4:10 to a 3.73. What do you think ? Ran a 9.80, just under 139, currently fitted with a 8" ATi treemaster that was originally specified for a 750hp 528, we were happy with it until we changed the gear shruggy
https://www.youtube.com/watch?v=7mEWmd1L_GM
Posted By: 572B1

Re: Blowing through the converter ? - 10/08/22 11:08 PM

ATI sold me a 9'' fuel and blown convertor for a 572 street engine.
Posted By: tex013

Re: Blowing through the converter ? - 10/09/22 04:43 AM

My 2 cents .
Was it ok with 4.1 gears ? Take gear out often seems to effectively loosen converter . Again imo that is a biggish gear change so would less likely now load converter .
I remember when i got my Satellite it had 2.92 gears 14" wheels and 4000ish stall , almost could not get it moving from stop on highway trip home . 3.91 gears and 28" rears it drove great

Tex
Posted By: fast68plymouth

Re: Blowing through the converter ? - 10/09/22 04:50 PM

Adding taller gears loads the converter harder.

Might have killed it.
Posted By: Tig

Re: Blowing through the converter ? - 10/09/22 05:33 PM

Originally Posted by fast68plymouth
Adding taller gears loads the converter harder.

Might have killed it.


Hmmm......I think you may be correct, IIRC the line temp was a lot higher than normal as well blush
Posted By: Cab_Burge

Re: Blowing through the converter ? - 10/09/22 07:59 PM

How about moving the shift point up to around 7000 RPM to see what that does for you twocents scope work
Posted By: Tig

Re: Blowing through the converter ? - 10/10/22 01:23 AM

Originally Posted by Cab_Burge
How about moving the shift point up to around 7000 RPM to see what that does for you twocents scope work


Last couple of passes we tried 6900 as the shift (rather than 6700) Ran roughly the same shruggy
Posted By: dizuster

Re: Blowing through the converter ? - 10/10/22 02:13 AM

In my opinion 600 rpm fall back is a little shy, but not terrible.

9.80@139 matches up, so it's not way down on trap speed for that ET or anything.
Posted By: Cab_Burge

Re: Blowing through the converter ? - 10/10/22 02:56 AM

Originally Posted by Tig
Originally Posted by Cab_Burge
How about moving the shift point up to around 7000 RPM to see what that does for you twocents scope work


Last couple of passes we tried 6900 as the shift (rather than 6700) Ran roughly the same shruggy

How hard is it to get another good converter made for your new combo now?
I like and use FTI brand now, but that is with a Powerglide made for 1300 to 1500 HP shifting around 8000 RPM up
Posted By: Tig

Re: Blowing through the converter ? - 10/10/22 10:17 AM

That above pass I shifted @ 6700 2nd to 3rd. The RPM dropped around 400 and it spent 7 seconds buzzing from 6300 ish to 7000 at the stripe. On the video and in the car it just feels and sounds like the rpm is almost constant for the entire pass.
I have a 9.5" ATi converter that was built for a 950ft/lb 655 that will be going in and it stalled around 5000 with that motor. But if the 655 is completed, I will be using that motor instead. Season is finished over here and we have an upcoming house move so it may be late next year be fore we are out again. My opinion is swaying to the conclusion that I've found the limit of the converter and it's either broken or just no longer up to the job. shruggy
I'll likely be buying a converter suitable for spray as we are contemplating putting a fogger kit on the 655 sometime. cool
Posted By: dvw

Re: Blowing through the converter ? - 10/10/22 01:27 PM

To be honest all I really pay attention to is shift fallback. Currently it has a 9.5 ATI. Falls back to 6200-6300 depending on temp and shift point. It's in high gear under 5 seconds. The Ultimate 9.5 is similar though fallback is about 200 rpm lower. ET/mph is about the same. 31.5 M/T's go thru @7250@149. Shift points from 6700-7200 really don't change anything.
Doug
Posted By: rb446

Re: Blowing through the converter ? - 10/10/22 02:59 PM

Originally Posted by Tig
That above pass I shifted @ 6700 2nd to 3rd. The RPM dropped around 400 and it spent 7 seconds buzzing from 6300 ish to 7000 at the stripe. On the video and in the car it just feels and sounds like the rpm is almost constant for the entire pass.
I have a 9.5" ATi converter that was built for a 950ft/lb 655 that will be going in and it stalled around 5000 with that motor. But if the 655 is completed, I will be using that motor instead. Season is finished over here and we have an upcoming house move so it may be late next year be fore we are out again. My opinion is swaying to the conclusion that I've found the limit of the converter and it's either broken or just no longer up to the job. shruggy
I'll likely be buying a converter suitable for spray as we are contemplating putting a fogger kit on the 655 sometime. cool


tsk are you sure?....
Posted By: Tig

Re: Blowing through the converter ? - 10/10/22 07:16 PM

Originally Posted by rb446
Originally Posted by Tig

we are contemplating putting a fogger kit on the 655 sometime. cool


tsk are you sure?....


It's the only way it will go 8.50 grin
Posted By: HardcoreB

Re: Blowing through the converter ? - 10/11/22 04:32 PM

I'd think you have enough to overwhelm a typical 8" mopar converter. Sounds like you have a 9.5"? ...put that in!!! There's gotta be some low hanging fruit for loosing weight in that car? Sounds like you have a nice engine, I'd put some time into loosing weight before I stepped-up the engine anymore. If noting else, you brakes will thank you.
Posted By: Tig

Re: Blowing through the converter ? - 10/11/22 05:23 PM

Originally Posted by HardcoreB
I'd think you have enough to overwhelm a typical 8" mopar converter. Sounds like you have a 9.5"? ...put that in!!! There's gotta be some low hanging fruit for loosing weight in that car? Sounds like you have a nice engine, I'd put some time into loosing weight before I stepped-up the engine anymore. If noting else, you brakes will thank you.


Biggest weight loss would be swapping out the cage to a CM one, it's not even a CDS one, it was made out of 1 3/4" steam pipe front to back. The tech guy was amazed how thick it was, even on the outside of the bends grin I'd guess swapping it would save 150 to 175 lbs but the cost shruggy. I also got it re-certed last time out and tech'd so we got another 3 years on every thing.I have a big 'chute as well but the car stops well just on the brakes only used it about twice just to see if it works.
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