M42 turbo fact thread

[jntar]

What's everyone here torquing their ARP head studs to?

85ftlbs in 3 step intervals as arp recommends.

[jntar]

Contemplating a turbo upgrade in the very near future. I'm trying to decide between the gt2560r vs gt2860rs. Both spool pretty quick, the 2560 about 500 rpm quicker, but the 2860 has a better flow at the top end. I wont be running more than 12psi and still on stock motor (haven't even started on the new engine build).

Thoughts on these two?

[econti]

Contemplating a turbo upgrade in the very near future. I'm trying to decide between the gt2560r vs gt2560rs. Both spool pretty quick, the 2560 about 500 rpm quicker, but the 2860 has a better flow at the top end. I wont be running more than 12psi and still on stock motor (haven't even started on the new engine build).

Thoughts on these two?

I suppose it depends what you want it for.
I'm trying to decide between GT2554 and GT2560.
My thinking is that I'm trying to supplement the powerband, not create it. So the 2560 seems like it should supplement the M42 powerband pretty well, and shouldn't run out of puff too much at the top end.
For me at least, the 2860 would be a little big I think.
Good part about those turbos is that flange size is the same for all T2s. So it's pretty easy to change between them.

What sort of power are you after?

[jntar]

I suppose it depends what you want it for.
I'm trying to decide between GT2554 and GT2560.
My thinking is that I'm trying to supplement the powerband, not create it. So the 2560 seems like it should supplement the M42 powerband pretty well, and shouldn't run out of puff too much at the top end.
For me at least, the 2860 would be a little big I think.
Good part about those turbos is that flange size is the same for all T2s. So it's pretty easy to change between them.

What sort of power are you after?

I found an s15 240sx t28 locally I'm thinking about. It's pretty close to the 2560 spec. I'm fine with 200whp, but my current td04h-15g greddy turbo has a large drop on top end above 5k rpm. I'm looking to get something that spools similar, but pulls to redline.

[ccsdo5]

^^ This is the same turbo I am trying to get from my friend. It's apparently pretty awesome on the sr20's. I know T25 with an hks wastegate (about 1 bar of boost) is somewhere around 200-250 I think for my friends 240sx. I think it'll be a good buy!

How/ where are you guys running coolant lines to the turbo? I am doing the mess under the intake stuff as well so can I get it from coolant pipe (the teal colored line in the picture below) and then return it to the cylinder head (also the teal line pictured below).

[elcoy]

So I decided against the S52 swap, and am going to keep the M42 and go turbo! Looking to get some advice/predictions on my build. I have read several build threads and am meeting with a local engine builder hopefully this week, because if I am really going to do this the Engineer in me has to do it as close to correct the first time as I can. Thoughts on the following setup for reliability/hp?

Compression goal: 8.5:1
Forged Pistons
Performance Valves and Springs
Polished and Balanced Stock Crank and Rods
Turbo Cam
Ported and Polished Head
ARP Hardware
MLS Gasket
Turbonetics Ball Bearing T3/T4 5 Bolt Turbine .63 a/r (High teens psi?)
SDS Stand Alone (Already Purchased)


Stay tuned for a build thread!

[MF DOOM]

So I decided against the S52 swap, and am going to keep the M42 and go turbo! Looking to get some advice/predictions on my build. I have read several build threads and am meeting with a local engine builder hopefully this week, because if I am really going to do this the Engineer in me has to do it as close to correct the first time as I can. Thoughts on the following setup for reliability/hp?

Compression goal: 8.5:1
Forged Pistons
Performance Valves and Springs
Polished and Balanced Stock Crank and Rods
Turbo Cam
Ported and Polished Head
ARP Hardware
MLS Gasket
Turbonetics Ball Bearing T3/T4 5 Bolt Turbine .63 a/r (High teens psi?)
SDS Stand Alone (Already Purchased)


Stay tuned for a build thread!

:)

Sounds like a promising build. You should give MM a call about a head. Might as well go with one of theirs and rev to 7700.

[wazzu70]

Whats your power goal? 9:1 compression would probably be better IMO.

Why such an ancient turbo choice? Are you getting it used for cheap??

[RedReplicant]

Is anyone still making a Megasquirt PNP unit for the M42?

[jntar]

Is anyone still making a Megasquirt PNP unit for the M42?

Yes And no. There is a company that sells an unauthorized version. I own one. However, they are not good. Mine is near impossible to tune and I wish I had built my own.

[elcoy]

Whats your power goal? 9:1 compression would probably be better IMO.

Why such an ancient turbo choice? Are you getting it used for cheap??

Ideally I am shooting for 300+

I guess I didn't know that was an ancient turbo, what would be a better choice?

[RedReplicant]

Yes And no. There is a company that sells an unauthorized version. I own one. However, they are not good. Mine is near impossible to tune and I wish I had built my own.

That's too bad. I guess the best option is to buy a used harness and make my own MS harness from it.

[Dj Buttchug]

That's too bad. I guess the best option is to buy a used harness and make my own MS harness from it.

Theres really no need to modify or make your own harness. You use the OEM 88 pin harness when you build a PNP unit.

[RedReplicant]

Theres really no need to modify or make your own harness. You use the OEM 88 pin harness when you build a PNP unit.

Are you cutting apart a stock ECU (they are expensive, relative, used) for the connector and making a breakout board? How are the coils driven?

[gwb72tii]

I just picked up a 1991 318i and I'm going to mod the motor somehow.
So the choice i think for me is a typical M50/M52 twincam, or turbo the M42

So you that drive you M42 turbo all the time, how is it? other than more horsepower, how's living with it everyday? This will become a daily driver for me.