Turboing an M42

Post Sat Apr 11, 2009 11:32 pm

I'm not veiring away from my charger project but I'm going to have a spare engine and fancey turboing it later on and I like to know things so, is there anything I'd have to do differently compared to my super charger? I take it I'll have to adjust the compression ratio etc but what else?

Rich

Post Sun Apr 12, 2009 1:09 pm

How much power do you want?

Post Sun Apr 12, 2009 1:28 pm

rix313 wrote:I'm not veiring away from my charger project but I'm going to have a spare engine and fancey turboing it later on and I like to know things so, is there anything I'd have to do differently compared to my super charger? I take it I'll have to adjust the compression ratio etc but what else?

Rich

Same rules apply for turbo charging as it does with supercharging. Although again, turbo charging the M42 and running the boost through a large intercooler which is very effective will give better results than the Eaton style supercharge conversions already done here. As long you choose the correct sized turbo and the boost doesn't fall away at high RPM, then you will have superior torque lower down than the centrifugal superchargers like the Rotrex and almost on par with the Eaton, more mid-range torque and higher power at high RPM then the Eaton but on par with the Rotrex.

However, mapping a turbo is harder than the supercharger, as you can just about guarentee what boost you have with a supercharger at any load/RPM site, whereas the turbo is varying under certain conditions.

I would imagine, but don't take this a set in stone until you research it further, you could run 10psi or maybe a little more with a turbo with the right mapping on a standard CR M42. More than that and I would change the rods, bolts and pistons but not lower the CR too much untill you start hitting more than 1 to 1.2 bar of boost.

With 10-12psi, I would expect around a 100bhp increase over standard if you keep the CR standard.

Post Mon Apr 13, 2009 4:56 pm

I spoke to a guy in Finland (iirc) via ye olde msn a while back who'd turboed his E36 318iS (M42 not M44) to 270bhp on stock internals/CR and he said it'd be running fine for over 18 months. Turbo M42 is something I'm seriously considering.

Post Mon Apr 13, 2009 8:34 pm

Have a look on M42club.com there are two threads about budget turbo builds aiming for sub $1000 builds with some very good results. Lots of people doing it on there, a lot more the the SC route.

Post Mon Apr 13, 2009 8:56 pm

Shall have a look.

There's an epic one on bmwfans.

Post Mon Apr 13, 2009 10:32 pm

Link please rich

Post Mon Apr 13, 2009 10:56 pm

No words to it but a very impressive build:

http://bmwfans.info/forums/internationa ... -M42B18_13

Post Tue Apr 14, 2009 10:49 am

hmm very nice but not quite budget!

Post Tue Apr 14, 2009 6:13 pm

There's one of the budget build on M42club. I can't find the other.

http://www.m42club.com/forums/showthread.php?t=7233

Post Tue Apr 14, 2009 10:29 pm

Well i was going to do a budget build i got a manifold and welded it up (it was a modified M50 one) but i really wanted to keep my car standard no turbo supercharger so i was selling it but its just too tempting to just build up a 250 bhp m42 with the turbo..
i was going to use Mod'd M50 manifold, TD04HL turbo off a Volvo (you need this as Garrett turbos hit the rocker cover) but the down side is TD04HL turbos are water cooled so you need to sort out water as well as oil feeds.
oil is simple you just use the feed from the plug on the side of your oil filter housing. as for the return it needs to be somewhere on the sump but it has to higher than your oil level or you will F*%k up your turbo.
most of this is on the M42 club website.
I think there is only 1 budget build on there that i looked at but that guy used standard ECU not an after market one

Post Tue Apr 14, 2009 10:52 pm

Thanks for that Pharoh

The S/C mounting is a realy pain in the testics and putting me off of it atm, cold feet and all that.

Post Wed Apr 15, 2009 9:31 am

There was a guy who had an article in PPC with a 205GTi, he turbo'd it by putting the turbo where the back box was, ran a big aluminium pipe back up the car to the inlet manifold and an oil scavenge pump. Worked out really well if I remember correctly, no intercooler, very little lag, (can't remember why) and no increase i under bonnet temperatures. Had a K&N cone filter running staright into the turbo inlet! Ran a big bore exhaust, but didn't really work so went back to a standard 205GTi exhaust and worked a treat, something to do with back pressures and maintaining flow.

This would be a very easy way to get a turbo onto an M42 and you wouldn't have to take the car off the road to get it running, just get an old back box and make evrything to fit on the bench. I'd be tempted to run a small oil tank in the boot with a 2 stage pump, (feed and return) but he ran oil lines to and from the turbo using a 1 stage scavenge pump to lift the oil back into the sump.

Not that I'm going to build a turbo you understand....

Post Wed Apr 15, 2009 9:39 am

There's been a bit of debate over whether or not rear mount turbos on E30s are really worth it, with some good arguments from both sides.

Maybe a bottom mount setup would work better when dealing with the space issue between the strut tower and the rocker cover?

Post Wed Apr 15, 2009 2:03 pm

i think the main problem with that setup is the lack of space between the engine and the side of the engine bay causing the turbo to hit the engine side wall.. only from what i understand though...

Post Wed Apr 15, 2009 3:02 pm

I think the rear mount turbo arguments hold true whether it's an E30 or not, but there is a lot being done in the states on corvettes and mustangs using twin turbos as there simply isn't enough space under the bonnet.

Found this on ebay though...

http://cgi.ebay.co.uk/BMW-M42-M44-Turbo ... 240%3A1318