big charger for a little rover

[karrionchris]

Quick question.

not my car but a fellow hotrod man. not quite sure how we ended up with it but we are putting a gm 6/71 supercharger onto a rover 3.5. the CR is 9.35:1.

We have both been doing alot of reading and all sorts different stories are told.

so if anyone can answer for defonate.
Is the charger to big to use?
if not then what boost will be best and would anything need to be done to the innerds of the engine (apart from cam)?

[topcatcustom]

Christ thats huge! I was suprised at how many big block V8's use 6-71 blowers- even the 460's...

[bigaldart]

As long as you underdrive it a LOT! It can be made to work. It will make a lot of boost and heat on a 3.5 though. Stock pistons will not take more than about 6-7 psi boost, for this you will need to be about 30% underdriven if not more. Difficult to be sure as it depends how well clearanced the blower is.
Like everything you can make it work but for a Rover 3.5 a 4-71 is a better choice. Alternatively a 4.6 or bigger would put you more in the ball park for a 6-71. What is the intended use? Race car, road car, show car? If race then door car, comp car etc?

Alan

[kiwicar]

I would just add that you will want to make sure it is tightly clearanced or it will just put heat into the inlet charge, and I would put lowering the compression to about 8.5:1 as a high priority as you can only underdrive the supercharger so much. I think you will still be looking at 15+ psi boost and unless you put a charge cooler in the inlet charge will be pretty hot is it is not going to be very efficient.
Best regards
Mike

[kiwi303]

Thats a BIG SC for a little engine... One of the Eaton M90's in the for sale section would be a better choice.

[JP.]

Way too big. Need so much underdrive that it costs more bhp then it will deliver. Better find a 5.0 for that blower and even with the 5.0 it needs to be underdriven.

Hope you'll have enough engines on spare cause you'll break a few.