Building a 300HP+ M10?

[BoostedE21]

If one were to build a 300+hp M10, what would you need? Yes I know a turbo (what spec turbo?), but how else would you build the motor; what CR, pistons, rods, crank shaft, cam, etc etc.

Just a discussion

[g323]

The BMW M12/13 turbo 1500 cc 4-cylinder turbocharged Formula One motor, based on the standard BMW M10 engine introduced in 1961, powered the F1 cars of Brabham, Arrows and Benetton and won the world championship in 1983.
As BMW M12, the engine design since the 1960s became one of the most successful engines in racing. Starting with the European Touring Car Championship, it was also used in Formula 2, expanded to two litre and fitted with four-valve heads, producing over 300 hp (224 kW). In the Deutsche Rennsport Meisterschaft, a 1400 cc variant (with a 1.4 handicap factor equal to 2000cc) was turbocharged by Paul Rosche according to FIA Group 5 rules. At well over 350 hp (261 kW) from the beginning, it rendered the normally aspirated engines in the two liter category useless. After some development, power, driveability and reliability improved, especially in the IMSA car, and BMW began to think about entering F1, where a handicap factor of 2.0 required 1500 cc engines.


With the BMW badged as Megatron in this A10B chassis, drivers Eddie Cheever (pictured at the 2008 Goodwood Festival of Speed) and Derek Warwick ensured that 1988 was Arrows' most successful year in Formula One, thanks to frequent points finishes.
In the years 1986 and 1987, the version M12/13/1 was tilted sideways by 72° for use in the extremely low Brabham BT55. The design was not successful, probably due to cooling issues in the tight compartement. Anyway, the 1986 engine was said to produce about 1,300 hp (969 kW) in qualifying.[1]

1,300 hp!!!

[ame]http://en.wikipedia.org/wiki/BMW_M12[/ame]

[Jmabarone]

I'd send my money to JRCook and have him do it.

but really, S14 crank and rods, forged pistons (probably 8.5:1), megasquirt, turbo, and water-methanol for fun/overboost. all other loose ends (cam, valves, valvetrain, etc) would be determined after a whole lot of reading.

[Layne]

I'm tempted to get a 2.5l short block, but good lord those are expensive. I'd only do that for WAY over 300hp.

You'll need one of these

This thread should answer all your questions and more:
http://forums.bimmerforums.com/forum...&highlight=M10

[BoostedE21]

Yeah that would be nice! Wish I had that money to throw around

[bflan2001]

what manifold is that???

[Layne]

what manifold is that???

Home made by a 19 year old kid. No joke.

Reading that thread is bad for my finances...

[jrcook320]

yeah, that was an impressive build. That kid has talent.

Here is what I think. Disclaimer: Having not yet built a 2.1L or 2.2L m10, I do not have personal experience with these suggestions. This is the theory that I will use when I do get to that point, however.

Bottom end:
Since you're going to buy pistons, you might as well bore it to 91mm which will give you aobut 2.1L. To hit 300 hp on a 2.1L m10, I'd start with forged pistons in the 8.5:1 CR range (I haven't done research there to know what CR is best). I would strongly consider spending a little extra to have the pistons and chambers coated. I'd use a total seal top compression ring and standard 2 & 3 rings. File your ring gaps for boost (you'll have to do some reading there, I don't have those numbers memorized). The stock crank & rods will be fine. Then you'll have to decide if you want to use a 2002 turbo cutting ring head gasket, an MLS gasket, or have the block o-ringed and use a stock gasket. I'd ask the guys at TEP what they think about that. ARP head studs are a really good idea as well.

Head:
Depending on how high you want to rev it (the higher you rev it, the more power you'll make and the longer you'll be in your power band), I'd get a TEP turbo grind cam, valve springs, and rocker retainers, for sure. If you want to rev over 7k, get aftermarket rockers. If you have the head ported, you'll make more power with less boost by increasing the VE% of the motor.

Turbo:
To hit 300 hp with a 2.1L, you'll have to run about 20 lbs of boost (a pressure ratio of about 2.44). The GT2860 can do that, but you'll be on the high end of it's map and out of the efficiency sweet spot. The GT2871 would be perfect, and has room to run even higher boost. You could potentially run as high as 25 psi (2.8 pressure ratio) and make up to 350+hp without sacrificing much on boost threshold, lag, and midrange power. If you push the GT2871 to a PR that high, again you're on the high end of the map and it might want to surge on you as well (that's speculation base on how far the left side of the map cuts in there). If you want 350 hp, I think the best turbo will be the GT3071.

If you happen to spring for the s-14 crank, you'll need to run s-14 rods as well. Now you'll have 2.2L to play with, and it looks like you'll be able to make the same power running ~2psi less boost than with a 2.1L. Now you can easily hit 300 hp running 18 lbs at a pressure ratio of 2.3. At that boost level I would for sure run the GT2860 or the GT2871. If you want more power, go with the gt2871 or gt3071 and run up to 25 psi, and make up to 350-375 hp. On the GT3071, you could turbo the boost up a little further and be pushing 400.

Ask what good n tight is running as well if that's the kind of motor you want to build.

If you'd like, I'll chart those numbers on compressor maps and post em up later.

[Turbo 3.8L E21]

If one were to build a 300+hp M10, what would you need? Yes I know a turbo (what spec turbo?), but how else would you build the motor; what CR, pistons, rods, crank shaft, cam, etc etc.

Just a discussion

3582R, 100shot of gass up its ass, theres ur easy 300+hp

it will most likely go bang on the second dyno pull though

[Layne]

I agree with everything except using TEP. I've never dealt with them personally, but based on what I've seen I wouldn't ask their advice on a handbag purchase, much less an engine build.

3582R

Does this mean something?

[jrcook320]

Lol, that means a GT3582R using rally style anti-lag fuel injection in front of the turbine to spool it. Good for 600-700 hp. That should do it.

[BoostedE21]

JR, thank you for posting, if you have the time and would like to, please do post the numbers & map(s).

One question though about the S14 crank and rods, do they just bolt right in? What kind of mods would need to be done on the chain and gear/pulley?

[Layne]

Lol, that means a GT3582R using rally style anti-lag fuel injection in front of the turbine to spool it. Good for 600-700 hp. That should do it.

Oh now that's actually cool. I assumed it was code for some japanese engine.

One question though about the S14 crank and rods, do they just bolt right in? What kind of mods would need to be done on the chain and gear/pulley?

There are mods necessary, but it's all documented to death. You have to bore out the front cover for a larger seal and use a S14 pulley. I believe the chain aligns fine with early M10 double row stuff.

[Jmabarone]

One question though about the S14 crank and rods, do they just bolt right in? What kind of mods would need to be done on the chain and gear/pulley?

http://www.77e21.info/strokerbuildbottomend.htm

[BoostedE21]

Ahh..thank you guys!

[milotrain]

I'd say in regards to cams that it might be worth talking to Elgin or one of the other grinders (rather than TEP who has more "off the shelf cam grinds"), you're making a motor to do a very specific thing in a very specific set of circumstances so the cam might want to be custom specific, even from a new raw billet like IE uses so that you can keep overlap down and lift high. Dunno though, just speculation.

It also might be worth running the S14 rods and rod ratio regardless of weather you use an S14 crank.

I dunno if it's possible but you could maybe bore it out over 94mm and wet sleeve it.

[jrcook320]

I dunno if it's possible but you could maybe bore it out over 94mm and wet sleeve it.

I've thought about that before. Has anyone ever done that to an m10 block before? Is it worth it when you can just run an s14 block?

What is the max bore for an s14 block? How about the evo 3 block? I've seen hints of up to 96mm bore for the evo 3 block.

[milotrain]

And further at what point is it not an M10? If I use a forged block of steel and machine it with 98mm cylinders, water jackets and journals for the S14 crank and stick an M10 head on it is it still an M10?

That's more of a metaphysical question than anything, but it's a reasonable one to consider.

[uberpanzer]

The road going Sport Evo III motors had a bore of 95mm. The Group A Sport Evo race motor had 95.5mm. But why do you want to keep boring out? BMW in the Turbo F1 engines were using around 89mm bore and 60mm of stroke. Granted they were also pushing 62.5psi of boost on race day and qualifying on 85psi (at least in '85) running on race fuel, but still. I would say stop playing with bores and just build it stronger at a smaller displacement for more boost and just keep dialing that up. That way once you DO need to rebuild and want to hone the walls a little, you have some metal to take out so you don't have to go buy a new block.

And further at what point is it not an M10? If I use a forged block of steel and machine it with 98mm cylinders, water jackets and journals for the S14 crank and stick an M10 head on it is it still an M10?

That's more of a metaphysical question than anything, but it's a reasonable one to consider.

I guess the REAL question is whether the S14 is a tarted up twin-cam M10 or not.

But seriously, block are almost the same, before bore work is done. I would say once you swap to a S14 head and ITBs THEN it is a S14. Single cam = M10 IMO.

[Layne]

S14 block can be bored 95mm, not sure how risky that is but people do it. EvoIII block has thicker cylinders (already comes 95mm) I haven't heard anything about overboring it though. A new one is $3000. It also has beefier main bearing areas and oil squirter holes. Bigger is always better, but if it's just a matter of turning up the boost a bit to save thousands of bucks, might as well go that way.

[Greenfield]

Why not supercharging? No fancy internals, no timebomb dyno pull engines good for one run.. I've been reading about MGs, TR-6s, Miatas, and more importantly m42 e30s that take a supercharge bolted on in a weekend and making big power. No spool up, just hit the gas and go. I know it may not make 300hp, but it should get close enough for government work.

Attila, I know you are already boosted, but for any old m10..why not supercharging?

[uberpanzer]

Boost is boost (within reason), and those blowers are are just running a lower boost level than high boosting turbo set-ups. Look at it this way, that e30 M42 with a Downing Atlanta kit (an Eaton blower that is Roots style) makes between 6-8psi. That is about what my BAE/Century kit made when it was new. Same applies for both, no internal mods needed, fuel can BASICALLY keep up with that on the stock system. But you are not going to see 300hp on a under 2.0L 4 banger with only 8psi of boost. The 1.8L M42 was making just shy of 200hp at the wheels with that set-up. At the end of the day, you aren't flowing enough air through the motor to make 300hp with those figures.

Supercharging is just as carnivorous of a monster as turbo. There are a couple different styles of blowers to go with, but at the end of the day it is all about pushing more air and fuel through the engine to make more power. Once you start trying to push enough of that stuff through a tiny motor, whether you are turbo, blown, or screaming-high rpm NA, you end up running into issues with the stock parts and have to upgrade beyond them.

....ask our resident Miata guys about the Jackson Racing blower kits (also using Eaton units). I'm sure they'll tell you of plenty of people pushing the limits of those that are have problems.

[jrcook320]

The road going Sport Evo III motors had a bore of 95mm. The Group A Sport Evo race motor had 95.5mm. But why do you want to keep boring out? BMW in the Turbo F1 engines were using around 89mm bore and 60mm of stroke. Granted they were also pushing 62.5psi of boost on race day and qualifying on 85psi (at least in '85) running on race fuel, but still. I would say stop playing with bores and just build it stronger at a smaller displacement for more boost and just keep dialing that up. That way once you DO need to rebuild and want to hone the walls a little, you have some metal to take out so you don't have to go buy a new block.

I guess the REAL question is whether the S14 is a tarted up twin-cam M10 or not.

But seriously, block are almost the same, before bore work is done. I would say once you swap to a S14 head and ITBs THEN it is a S14. Single cam = M10 IMO.

I agree, if you put an m10 head on it, it's a big bore m10. The reason I want to go for maximum displacement is because "there is no replacement for displacement", not even boost. Sure, I can run higher boost, but once you start looking at the numbers, you'll realize that may not be ideal for making streetable power. Peak HP is NOT my goal. Area under the curve with gobs of low end torque is. Sizing a turbo to make 350+ hp on a 1.8 or 2.0L SOHC motor means you're going to give up drivability, boost threshold, lag, etc. An 1.8-2.0L m10 does not equal the SR20DET, M42/44, or B16 or other high tech DOHC 4 cyl that makes gobs of power with reasonable boost levels. The problem lies with the relatively low volumetric efficiency with a SOHC. It simply doesn't flow the amount of air a more efficient DOHC motor will. I estimate that you'd have to run 27lbs of boost (PR=2.9) to make ~300 hp on a 1.8L m10. Try to graph that on a compressor map! To get a turbo big enough to run a pressure ratio that high means it's going to have high boost threshold, lag, and poor midrange power, and it will end up being an on-off motor when it comes to power band. I don't want a motor that doesn't spool until 3500 rpm, then when it does spool the power spikes from 100hp to 300 hp within 500 rpm. Try to drive that on an autox course or put that power down coming out of a turn on a track.

I autox with a supra with a huge turbo that is probably pretty fast.. on the drag strip or highway. You can hear the turbo start to whistle on an autox course, but he can never even get in the boost. That kind of power is useless to me.

If I find a deal on an s14 bottom end, I'd buy it. Why spend money to bore an m10 block to 91mm when I can have 93mm stock with the stock s14 block? I already have a knife edged crank. I need rods and a block…

I dunno, I'm the type of guy that just needs to build low boost turbo 3.8L m30 an be done with it. Then I think about the weight and loosing that feel the e21 has and go back to trying to build the biggest displacement m10 possible.

S14 block can be bored 95mm, not sure how risky that is but people do it. EvoIII block has thicker cylinders (already comes 95mm) I haven't heard anything about overboring it though. A new one is $3000. It also has beefier main bearing areas and oil squirter holes. Bigger is always better, but if it's just a matter of turning up the boost a bit to save thousands of bucks, might as well go that way.

95mm is what I thought...

[Greenfield]

I get what you are saying, Doug. I've always read that supercharging was gentler on an engine, even going so far as to point out that you can forgo a lot of the internal modifications required of a boosted engine? My preference has always been a N/A engine, especially after seeing the Panoz LMP cars smoking the turbo Audis on short courses about 8 years ago, but that's besides the point. If the 1.8 m42 with a supercharger makes 200rwhp, can we for the sake of this argument say that's 240hp at the crank? If you open up the breathing on an m10...ah, nevermind. I'm not gonna be any help on this one. I'd be happy with 200hp N/A at the wheels.

[Layne]

If I find a deal on an s14 bottom end, I'd buy it. Why spend money to bore an m10 block to 91mm when I can have 93mm stock with the stock s14 block? I already have a knife edged crank. I need rods and a block…

I don't see any 'deals'. The last block I missed out on was $400 and I haven't found another. Cranks are $300 and rods at least $200+. There's a 2.5l short block for $4500 that I can't stop thinking about. I'm wondering if you could use the S14 pistons if you cut new valve cutouts into them and just ignored the old valve cutouts. The dish top would make for really low compression on an M10 head.

I've always read that supercharging was gentler on an engine, even going so far as to point out that you can forgo a lot of the internal modifications required of a boosted engine?

The engine doesn't know or care where the pressure is coming from. It's just that S/Cs are usually lower pressure than turbos and that's why you wouldn't need to mod the engine. There's no rule though, either one can be as high or low of pressure as you want.