Converter Question

I'm moving from a naturally aspirated BBC with PG and 8" 5500 stall converter - to a 355 6-71 blown sbc using the same PG. The 355 is not a killer - about 16 lb boost. Can I use my existing converter?...or should I be changing it for a lower stall converter?....Any help would be appreciated. Will be using a C02 launch controller
Thanks all
Phil

 

I'd def. start of using the same thing you already have. Before you send it off to be opened (weld together?); see what it shows you on the launch and at the shift point(s). To me it sounds like the motors are somewhat close to the same, had the previous motor been nitrous a change might have been more called for. Usually the converters I have seen in lower hp cars are too tight to begin with, so now if you're making more power (even a little bit), the converter should be that much closer. Do you have a data recorder on board? Even if it's not perfect, I'm sure we're only talking a stator change of a few degrees.

Brandon Booher
Torque MGMT. - Owner
NHRA TAD #323
217-840-1500

 

Thanks Brandon. I kiind of figured that. What should my launch RPM be using this converter?

 

It's really hard to say, so many variables. I would be confident in saying 4200-4500 would be safe. It'd be better to start what some may consider low and re-chip it as you go than to knock the tires off and learn nothing. We ran a SBC w/ a 10-71 in a dragster, ran very well with it and we launched around 5400 or so.

Brandon Booher
NHRA TAD #34

 

OK Brandon....last question - When you say "re-chip" to sneak up to the correct-for-the-car launch - you mean using a 2-step? I would have thought that chip'ing it while staged would drown the fuel system waiting on the lights to come down. I'm using an MSD 10 so a 2-step is a simple add. If the 2-step is the way you say I should go, then that makes life simple.
Thanks again

 

Yes a 2 step, use an air cylinder to keep the blades at the chipped rpm. This will keep you from opening the barrel valve and flooding the engine like you mentioned.

Brandon Booher
NHRA TAD #34