Hi guys,

A friend of mine owns a LS1 powered Holden Monaro with 495fwhp and after recently changing hi-stalls lost 70rwhp between the two.

Both converters are made by an Australian company which have been making hi-stalls for years.

With the first converter which was 2500rpms it made 390rwhp.
With the second converter which was 3800rpms it made 320rwhp.

They have swapped back and forth a couple of times and each time it produces the same results. This loss seems way too high? I wouldn't think you would lose that much by swapping hi-stalls.

What have others here lost at the rear wheels by going up stall speeds? Any help is greatly appreciated.

Brett.

 

jesus...I have no idea that's just entirely crazy

 

It is crazy. Is there meant to be any power loss between a 2500rpm and 3800rpm converter? If so how much would be an acceptable loss?

Brett.

 

To lose more then maybe 5-15hp between the stalls is crazy. If the second converter was defective and extremely loose, there would be a small amount of loss, but still not that much. There is something wrong with the second converter. Usually a 2500 to 3800 would be about a 3% loss. Cannot say exacxtly what the difference would be though.

 

I think there is something wrong with converter #2. To drop more than 5% is unusual. It could be a really bad design (i.e. the builder took the 2500 stall and just bent the pump blades backwards to get to 3800) or something is damaged internally.

Have you tried manually locking the converter to see if the HP returns on the dyno?

BTW, occasionaly loose converters play havoc with a dyno, but normally the peak HP is correct but the TQ and RPM scale are skewed.

 

what do your rwtq #'s looks like? I don't like dyno #'s much, only real way to know is to take it to the track. I would contact the converter company and talk to them about it.

 

Was the converter locked on the 3800? A locked vs. non-locked converter will give results similar to that. The difference is, a non-locked converter will give higher tq values when compared to the locked converter.

 

Thanks for the responses guys.

FASST - The 3800 is a non-lockup converter and the 2500 has lockup. Pretty sure that both converters were unlocked when on the dyno so the loss is far too high.

CamaroCain - Fairly sure that torque is dropping off also, but will make sure.

Ragtop 99 - As above the 3800 is non-lockup so we can't test that on the dyno.

I am sending up my Yank PY3400E converter for them to bolt in to check rwhp then. So far it looks like the top end efficiency of the 3800 they have is bad but this will make sure it is. If the converter is at fault then the company is going to rebuild it until the loss is acceptable.

Brett.