External links now open in a new browser tab - turn this off in your UCP - Read more here.

will a b35 head and thic gasket lower my compression enough?

Discussion pertaining to positive pressure E28s.
Post Reply
photo500
Posts: 86
Joined: May 16, 2007 12:25 AM
Location: Perth, Western Australia

will a b35 head and thic gasket lower my compression enough?

Post by photo500 »

Hi guys,
I have a 10:1 comp m30 3.5L in my e28. What you would all call a dirty motor. I also have a ported and polished b35 head sitting around. Would using that head lower the compression enough to allow me to turbo this motor or will I need a thick MLS head gasket as well and if so what thickness would be the best? Any ideas what CR I'd end up with?

Cheers

Adam
red535t
Posts: 204
Joined: Jun 03, 2007 4:53 PM
Location: auckland,new zealand

Post by red535t »

Hey Adam

Did the same with my engine build for the FI.
although i did install 9.0-1 pistons,I fitted a steel and grafite sandwich gasket.
got the guy to make it 30% thicker then standard,after torqueing.
Ihave no idea what ratio it running,but still had enough getup and go to stick with my mates who have the same model etc. before we started adding extras.
from memory running 180 psi per cylinder.which isnt far off being accepptable in a stock situation,according to my manual

As for your plan i dont know how much more it needs to be, (75%)??
but its definatly cheaper.
check out red535t on photobucket.com for a few pics etc.

cheers marty (nz)
Bert-Ola
Posts: 170
Joined: Feb 12, 2006 12:00 PM
Location: Karlskrona/ Sweden
Contact:

Re: will a b35 head and thic gasket lower my compression eno

Post by Bert-Ola »

photo500 wrote:Hi guys,
I have a 10:1 comp m30 3.5L in my e28. What you would all call a dirty motor. I also have a ported and polished b35 head sitting around. Would using that head lower the compression enough to allow me to turbo this motor or will I need a thick MLS head gasket as well and if so what thickness would be the best?
Just changing to the M30B35 head gives 9,1:1 in comp on your M30B34 engine.
photo500
Posts: 86
Joined: May 16, 2007 12:25 AM
Location: Perth, Western Australia

Post by photo500 »

Alright cool, thanks guys, I guess I can go ahead now and see how it ends up. I was only planning to run low boost anyway in the beginning. I will still get the ARP head studs and a new gasket though as that seems like a good idea. I have a fuel controller that intercepts the signal from the AFM and changes it to what ever I like so I'm pretty sure I can get away without a RRFPR. Thanks for all the help, makes living in western australia not seem so isolated afterall ;)
M. Holtmeier
Posts: 3036
Joined: Mar 11, 2007 3:06 AM
Location: Josephine, Texas

Post by M. Holtmeier »

photo500 wrote: I have a fuel controller that intercepts the signal from the AFM and changes it to what ever I like so I'm pretty sure I can get away without a RRFPR.
It's not a MapEcu is it? :down:
Bert-Ola
Posts: 170
Joined: Feb 12, 2006 12:00 PM
Location: Karlskrona/ Sweden
Contact:

Post by Bert-Ola »

If you use the 2 mm thick gasket you get 8,9:1.
photo500
Posts: 86
Joined: May 16, 2007 12:25 AM
Location: Perth, Western Australia

Post by photo500 »

Its a Jaycar unit actually, which is one I made up myself

http://www.jaycar.com.au/productView.as ... BCATID=347

Jaycar have quite a few really cool kits and they are cheap too. Do you guys get them over there?

Thanks Bert for the gasket info, is 2mm available in the MLS gaskets off the shelf or would it need to be custom made?
Post Reply