High compression turbo feasibility in a Bav

Discussion pertaining to positive pressure E28s.
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foolish
Posts: 416
Joined: Apr 08, 2010 2:21 PM
Location: Western Mass

High compression turbo feasibility in a Bav

Post by foolish »

I am in the planning stages of a engine swap into a 72 Bavaria and am considering a simple relatively low power turbo option. I already have a fully rebuilt B35 with PB 10.5:1 pistons, N21 cam, and megasquirt in an E30 that I could use. I also have a B34 of unknown history and mileage that has a broken rocker at my disposal.

Is it feasible to turbo the B35 using low boost (8-10) on 93 octane using a TCD bottom mount manifold ( with or without intercooler)? If intercooled I think it would need to be W2A due to not wanting to hack up the E3 sheet metal and I plan on functional A/C. I could also go with a different cam in the B35 if it would work.

If I end up needing to use the B34 block I am also considering getting some regular B35 pistons and cam and using my B35 head because the head is already in excellent condition. I am aware that I will need to use the B34 oil pan no matter what block is used to fit the Bav subframe.

The car will also be getting an E28 rear subframe and
I have a 3.46 diff to use. I converted the fuel tank for fuel injection so it now has a in tank 190 lph pump. Is that pump sufficient for my plans?

I also recently picked up a semi-full 15 lb nitrous bottle and line that I picked up for $25 in case I lose my mind.

I would appreciate any feedback on these options.


Thanks
marc79euro645
Posts: 444
Joined: Dec 09, 2008 12:33 AM

Re: High compression turbo feasibility in a Bav

Post by marc79euro645 »

The nitrous might be a good option. You would have a much easier install, no need for i/c, less plumbing and hacking.
foolish
Posts: 416
Joined: Apr 08, 2010 2:21 PM
Location: Western Mass

Re: High compression turbo feasibility in a Bav

Post by foolish »

I am sort of leaning toward just running the B35 as is for a while and then maybe running a 75 hp dry shot because it would be as you said quite simple simple and could be easily controlled by the ms3x. I would only use the NOS sparingly, at least that's what I tell myself.
tschultz
Posts: 3904
Joined: Mar 01, 2009 8:58 PM
Location: Denver, Colorado
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Re: High compression turbo feasibility in a Bav

Post by tschultz »

For the complexity, I'm not sure a turbo makes sense with that compression ratio and low boost you might be able to run.
As I understand, M30 large combustion chamber has much more propensity to preignite as compared to later M50 motor which flows better in general boost and is better suited to boost from that perspective. Of course it comes down to to tune so I would say it may make sense if you had a way to sense for knock.

But a 10.5:1 B35 should be pretty sweet by itself, especially in a lighter Bavaria.
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