s38b36 conversion - The Unofficial BMW M5 Messageboard (m5board.com)

dicey2 · 12th August 2009, 12:33

i have come a come across a very cheap 1991 e34 m5 with the s38b36 engine here in ireland

i had a quick search but cant find a definitive answer on this

do i use the m5 box?
which prop?
exhaust/manifold?
diff?
rad?
mounts for engine/box?

any info greatly appreciated

thanks

Arjun75 · 12th August 2009, 13:20

Im in the process of doing a similar conversion myself.My car is an 84 518 which i bought midle of last year.Its getting the s38b36 from a 91 M5 which i bought and stripped for parts.the gearbox is from the m5,the prop needs some work as the length needs to be altered and then balanced.Diff housing is from the e28 with the diff of the m5.using a fritz exhaust and i have been told that the m535i engine mounts fit pretty good .Thinking of either using the radiator from an e28 535i or getting one custom made.

Also bought an e28 M535i in the uk and stripped for the other parts i needed since its very hard to source parts for these cars here.

The original brake booster does not clear the s38b36 intake plenum so need to do a custom brake job as well.either that or fabricate a plenum to clear the original brake set up.

Hope all this works out as planned

dicey2 · 12th August 2009, 13:37

thanks boss

which prop needs to be shortened?

my 535i has a full fritz system inc manifold - is that ok to use?

what are you doing about replocating the brake booster?

Arjun75 · 12th August 2009, 13:48

Well using the front prop from the m5 which most likely will be the one which will be cut.Rear from the m535i e28.

As for the brakes planning a smaller booster which i recan will have better pedal feel as well...im not sure though.Either that or very commonly folks use the booster from a vw golf and it seems to work.Have not got to that yet so cant be a 100 percent sure.

I doubt if you can use the m30 manifold onto the s38.the section after the header could be used but i dont think an m30 manifold would go onto an s38.check with richard at fritz ,he should be able to help you out on this.

dicey2 · 12th August 2009, 13:51

whats your thinking on the route you will take - will you relocate the booster or modify the plenum?

Arjun75 · 12th August 2009, 14:01

thought of a dual master cylinder set up with a custom pedal box.to be honest its gona be some time before we work on the brakes so still have our options open.Will not cut the plenum though.

dicey2 · 12th August 2009, 14:45

hold on a sec when you say booster you actually mean servo?

there is no servo on a 535. there is a brake bomb. other e28s used servos - whereas the 535i used the bomb. your car is a 518 so you would have the servo.

im just wondering will i have that problem with my bomb?

Arjun75 · 13th August 2009, 07:39

using the braking setup from the m535i looks like the plenum will not have any fouling issues.its going to be a tight fit but should be ok.i found a pic of an e28 engine bay with the s38b36 in it and its got the standard brake set up.

Are you going to upgrade the brakes.What diff ratio you planning to run? Also whats the suspension set up yu are running ie Shocks and springs and anti roll bar?

dicey2 · 13th August 2009, 11:54

Quote:

Originally Posted by Arjun75

using the braking setup from the m535i looks like the plenum will not have any fouling issues.its going to be a tight fit but should be ok.i found a pic of an e28 engine bay with the s38b36 in it and its got the standard brake set up.

Are you going to upgrade the brakes.What diff ratio you planning to run? Also whats the suspension set up yu are running ie Shocks and springs and anti roll bar?

hi boss

i have already upgraded my brakes to e34 m5 3.6 ARBS are also upgraded to whiteline. Im running new bilsteins sport shocks and eibach prokit springs

i spoke with a guy in the uk last night who has already done this using his e28 m5.

he used the nearside e28 m30 engine mount, but the offside will not fit and you'll need to fabricate one or buy one. (somewhere in the US sells them i think )

You could use the M5 box but you would need to get your prop shortened to fit. he also rekoned i could use my dogleg box and prop
You would need the radiator and exhaust manifold from an e28 M5. A custom radiator and Fritz manifold Massive stocks of older BMW parts and vehicles : fritsbits.co.uk : may be the way to go.

The e28 M5 has a large case 3.73 diff while the e34 m5 is 3.91. the nearest to this would be the 3.64 from a Highline 6 series, or you could get a diff rebuilt using e34 innards in an e28 large case.

There would be the oil cooler and coolant plumbing to sort and you would need to move the expansion tank mount and resite it somwhere else as it's in the way of the inlet manifold. you also need to move the power steering fluid reservoir forward a bit too

The airbox occupies the space where the battery sits so you will need to move the battery to the boot.

also as you know work will be required to match the e34 engine loom to the e28 as the connectors don't match. The ECU on the e34 is under the bonnet so the engine loom isn't long enough to fit the ECU behind the glovebox in the original e28 position.

so what ya think of that!

Arjun75 · 13th August 2009, 13:29

Hi there.

Reg the engine mounts, koala motorsports in the states sells mounts for the e28 to take an s38.Since i have the mounts from the e28 m535i im going to see how i can use them.Fritz seems tothink they should do.I hope so anyway otherwise will resort to some fabricating i guess.

Using the brakes fromt the m5 as well.As far as the electronics are concerned,at the moment looks like we are going with a standalone MoTech set up.Thinking of running a 3.91 diff.Engine is getting a full rebuild at the moment with 11.5:1 CR Forged Alusil Pistons which will effectively make it a 3.7 or close at least.Other than that its just the fritz exhaust as i already mentioned.

Yep moving the battery to the boot and thinking of going with the standard bilstein mtec set up with stiffer bars.how do you like the set up you have with the whiteline bars?