e92 M3 Turbo Conversion

[Keik E92 M3]

So i am curious why there has only been one Turbo build for the e9X M3. Is it that much difficult to fabricate a kit for this motor?

[tibra1]

Engine block didnt hold is my guess

[C|3R1C]

The people who tried had issues fitting the turbo somewhere. And something about superchargers makes more low end torque over turbos. I'm not sure how true the last statement is.

[Keik E92 M3]

hummm or is this just something people have turned away from? I just not seeing why this isn't a popular thing.

[BPMSport]

Space constraints, tuning.. etc..

Much easier to build a S/C kit over a turbo kit.

[Singletrack]

Weight, cost, space.

Supercharged M3 is already super-car fast and a fairly easy install compared to a turbo kit.

[M3 Maestro]

Comes down to multiple factors like a few mentioned above (packaging, software, part count, risk, investment vs. return, etc). Doing a basic decision analysis will lead your typical tuner to choose supercharger over the turbocharger from a business perspective.

Can a turbo system be done on this engine? Of course and it would be an awesome machine my friend.

[Lorde]

Originally Posted by Singletrack

Weight, cost, space.

Supercharged M3 is already super-car fast and a fairly easy install compared to a turbo kit.

I can only imagine what kind of a nightmare a turbo kit would be to install.

[pbonsalb]

12:1 compression is not turbo friendly on pump gas. Turbos typically produce full boost in the midrange, whereas the centrifugal supercharger produces roughly the square root of full boost in the midrange. The added boost at peak cylinder pressure is too much for stock compression on pump gas.

Look at the HPF E46M3 turbos on pump gas alone. They make no more power and torque than a stage 2 centrifugal supercharger E46M3 on pump gas. In addition to the compression issues, there is also the issue of the cam overlap on the high revving S54 and S65 that bleeds off midrange cylinder pressure in exchange for better top end filling. The centrifugal that feeds boost in gradually and makes peak boost only briefly and only at engine redline actually suits these motors pretty well.

Go to pump gas plus meth or race gas and more boost can be used. The turbo then runs away from the centrifugal supercharger. The centrifugal can be tuned for pump gas plus meth or race gas as well, but there is no easy way to detune it for straight pump gas. With a turbo, you can simply reduce boost through an electronic boost controller that regulates the wastegate. There is no "variable pulley" to reduce the speed of the belt driven supercharger to reduce boost.

[pbonsalb]

Originally Posted by Snig

I can only imagine what kind of a nightmare a turbo kit would be to install.

There are turbo kits for domestic V8s like the new Ford Mustang. I have not studied the E9xM3 engine bay with this in mind but a single or twin is probably possible with some creativity Given the lower volume of the M3, costs would be much higher since the market is smaller.

[M3 Maestro]

Originally Posted by pbonsalb

There are turbo kits for domestic V8s like the new Ford Mustang. I have not studied the E9xM3 engine bay with this in mind but a single or twin is probably possible with some creativity Given the lower volume of the M3, costs would be much higher since the market is smaller.

Twins for 600 - 800hp range will fit nicely (I measured already). 1000hp+ setups will be a bit more work but still doable. The intakes to the compressor stages and charge tubes are challenging but doable. Again the higher hp setups are more challenging there as well, need to watch deltaP through the tubes if you go small for fitment. Also did multiple engine simulations for these setups, very promising. Maybe one day when I have time lol.

[m3an]

Originally Posted by M3 Maestro

Twins for 600 - 800hp range will fit nicely (I measured already). 1000hp+ setups will be a bit more work but still doable. The intakes to the compressor stages and charge tubes are challenging but doable. Again the higher hp setups are more challenging there as well, need to watch deltaP through the tubes if you go small for fitment. Also did multiple engine simulations for these setups, very promising. Maybe one day when I have time lol.

I always putz around the idea, but time and reality then kick in. I could see twins being doable but rather do a single maybe on pass side (no steering) and can removed the overflow and reloocate ps reservoirs and maybe do a top mount(?). It does look like there is room, but I def don't think it's worth it unless you do a low comp built bottom end and run some decent boost. Or maybe try some thicker head gaskets at first, but anyway you look at it, it def cost some money. From what you said too, think of a single on the pass sided, compressor housing clocked... gives you a straight shot with a minimal bend to the intake, and would be less packaging than doing a twin setup.

[Rekrul]

Originally Posted by pbonsalb

12:1 compression is not turbo friendly on pump gas. Turbos typically produce full boost in the midrange, whereas the centrifugal supercharger produces roughly the square root of full boost in the midrange. The added boost at peak cylinder pressure is too much for stock compression on pump gas.

Look at the HPF E46M3 turbos on pump gas alone. They make no more power and torque than a stage 2 centrifugal supercharger E46M3 on pump gas. In addition to the compression issues, there is also the issue of the cam overlap on the high revving S54 and S65 that bleeds off midrange cylinder pressure in exchange for better top end filling. The centrifugal that feeds boost in gradually and makes peak boost only briefly and only at engine redline actually suits these motors pretty well.

Go to pump gas plus meth or race gas and more boost can be used. The turbo then runs away from the centrifugal supercharger. The centrifugal can be tuned for pump gas plus meth or race gas as well, but there is no easy way to detune it for straight pump gas. With a turbo, you can simply reduce boost through an electronic boost controller that regulates the wastegate. There is no "variable pulley" to reduce the speed of the belt driven supercharger to reduce boost.

Nice post... good info here.

[tightie]

Originally Posted by keikdasneak

So i am curious why there has only been one Turbo build for the e9X M3. Is it that much difficult to fabricate a kit for this motor?

There was one... Right handed drive, single turbo.

I've still been waiting to get more information but never happen.

Other then that, we are all screwed with superchargers.

[Stealth ///M]

Originally Posted by C|3R1C

The people who tried had issues fitting the turbo somewhere. And something about superchargers makes more low end torque over turbos. I'm not sure how true the last statement is.

Centrifugal Superchargers make very little low end tq. You definitely heard wrong..

[M3 Maestro]

Originally Posted by Stealth ///M

Centrifugal Superchargers make very little low end tq. You definitely heard wrong..

Stealth is right, turbochargers will have a more aggressive torque rise compared to the centrifugals because they are powered by the turbine wheel and not attached to the crank. Now the comment you heard could have been regarding a twin screw type supercharger, they will have good torque rise.

Off road diesels usually have high torque requirements at low engine speeds. In a case like this we may select a VGT turbocharger allowing the calibrator (tuners) to increase shaft speed and drive the compressor(s) to high pressure ratios delivering the target boost pressure for "xx" a/f ratio at "x" operating point (extremely simplified example). In no way am I saying put a VGT on the M3 lol...just pointing out options we (turbo engineers) use to hit performance targets.

Pbanslab pointed out the HPF kits make similar power (on pump) compared to some supercharger kits. He is 100% correct however it doesn't mean it needs to be this way. You can change the "theoretical" available torque through the turbo match. This doesn't mean throw on a smaller a/r housing to spool up quicker, I am talking about both stages. The tuner can also take advantage of cam phasing or dual VANOS as BMW has named it . With a load dyno you can sit there and run DOEs for physical testing or if you had the engine model you can do it in simulation. Many engine simulation software suites have optimizers which will get you really close saving you time and fuel.

We can certainly take this thread much more technically deep but I think the original question was simply why aren't tuners offering the turbo option.

[Stealth ///M]

Originally Posted by M3 Maestro

Stealth is right, turbochargers will have a more aggressive torque rise compared to the centrifugals because they are powered by the turbine wheel and not attached to the crank. Now the comment you heard could have been regarding a twin screw type supercharger, they will have good torque rise.

Off road diesels usually have high torque requirements at low engine speeds. In a case like this we may select a VGT turbocharger allowing the calibrator (tuners) to increase shaft speed and drive the compressor(s) to high pressure ratios delivering the target boost pressure for "xx" a/f ratio at "x" operating point (extremely simplified example). In no way am I saying put a VGT on the M3 lol...just pointing out options we (turbo engineers) use to hit performance targets.

Pbanslab pointed out the HPF kits make similar power (on pump) compared to some supercharger kits. He is 100% correct however it doesn't mean it needs to be this way. You can change the "theoretical" available torque through the turbo match. This doesn't mean throw on a smaller a/r housing to spool up quicker, I am talking about both stages. The tuner can also take advantage of cam phasing or dual VANOS as BMW has named it . With a load dyno you can sit there and run DOEs for physical testing or if you had the engine model you can do it in simulation. Many engine simulation software suites have optimizers which will get you really close saving you time and fuel.

We can certainly take this thread much more technically deep but I think the original question was simply why aren't tuners offering the turbo option.

Theyre afraid to. Cost vs. profit.

I will be attempting a single kit this winter.

I'll be reaching out to a particular tuner for his help.

[Keik E92 M3]

Originally Posted by Stealth ///M

Theyre afraid to. Cost vs. profit.

I will be attempting a single kit this winter.

I'll be reaching out to a particular tuner for his help.

Let us know how this goes, I am thinking about it as well.

[Keik E92 M3]

Anyone know of any company's who would be able to create a custom exhaust manifold for a Single turbo setup? I am really looking into doing this. If so I am willing to build a low compression engine.

[m3an]

what about a roots style blower?? That might be the answer to the torque we been looking for.

[pbonsalb]

They have them for the Ford Mustang 5.0. Relatively cheap, too.

[ScorpionT]

Originally Posted by talontid

what about a roots style blower?? That might be the answer to the torque we been looking for.

Roots blowers are horribly inefficient compared with other superchargers. A twin screw would be the single best option for low end torque and consistent power, but the cost is rather high. I would love to see someone develop and option for the S85 but I dont see anyone doing it anytime soon.