I have a few questions for my own curiousity. I have an e30 with e34 3.5l (m30b35) implanted engine and also an e28 m5 (s38b35). I know all the mechanical differences between the two engines and how they feel and run but i dont know the flow rates of the heads.

I noticed that they both run about the same size exhaust pipes even tho the s38 comes with short dual 3 to 1 headers and the m30 comes with dual cast manifold as well as the s38 having itb vs the m30 stb. I also know that unresticted, IT IS SAID that the s38 doesnt really see much of a gain while the m30 can see as much as 15hp at the crank. Of course the s38 is dohc 4 valve and the m30 is sohc with 2 big valves. The s38 also has higher compression.

Now this may not be a brain tease question and in fact i may already know the answer but im trying to see what other info may be out there. So the question is... given the same aspects such as compression, throttle body/ intake setup, exhaust, etc.... Which engine would your prefer?

Me personally, I love the m30 engine. The s38 is a wonderful engine but it has to be slapped around alittle before it slaps back. The m30 sets it off and slaps first. Other reasons being i can get satisfying power out of a m30 without the maintainance and cost headache of the s38.

Even tho i have had e28 535's with bolt ons that would give a stock e28 m5 a good run i dont know what a m30b35 in a e28 body feels like so i cant comment on what the 2 motors in the same body would feel like. I feel given the same exhaust, intake, etc the m30 may outperform the s38 but knowing the advantages of a dohc raises some conflicts in my thoughts.

So there it is. Chime in, tell your opinions and facts. Sorry if this a rethread.

I'd pick the M30 over the S38. The S38 is nice and exotic, but it's very fragile in comparison to the M30. When you factor the cost of maintaining/repairing/replacing parts in an S38 it's a no brainer. The M30 has tons of torque right where you need it. If your ultimate goal is big horsepower, you can get to S38 levels and beyond with a cam and a turbo for WAY less than you'd dump into the S38 keeping it happy.

There's my .02. Good luck whatever you decide.

I'd pick the M30 over the S38. The S38 is nice and exotic, but it's very fragile in comparison to the M30. When you factor the cost of maintaining/repairing/replacing parts in an S38 it's a no brainer. The M30 has tons of torque right where you need it. If your ultimate goal is big horsepower, you can get to S38 levels and beyond with a cam and a turbo for WAY less than you'd dump into the S38 keeping it happy.

There's my .02. Good luck whatever you decide.
Thanks for the response. Its not a decision im trying to make but its more of me trying to get it straight in my own head about the 2 engines. I think your speaking of stock motors and i agree with you 100%.

M30 s38 ITBs FTW

Boost the M30. DOHC is for suckas..:D

uh, the s38 isn't a b35, it's either a b36 or a b38.

uh, the s38 isn't a b35, it's either a b36 or a b38.

There was a s38b35: http://www.usautoparts.net/bmw/engines/s38.htm

I have a few questions for my own curiousity. I have an e30 with e34 3.5l (m30b35) implanted engine and also an e28 m5 (s38b35). I know all the mechanical differences between the two engines and how they feel and run but i dont know the flow rates of the heads.

I noticed that they both run about the same size exhaust pipes even tho the s38 comes with short dual 3 to 1 headers and the m30 comes with dual cast manifold as well as the s38 having itb vs the m30 stb. I also know that unresticted, IT IS SAID that the s38 doesnt really see much of a gain while the m30 can see as much as 15hp at the crank. Of course the s38 is dohc 4 valve and the m30 is sohc with 2 big valves. The s38 also has higher compression.

Now this may not be a brain tease question and in fact i may already know the answer but im trying to see what other info may be out there. So the question is... given the same aspects such as compression, throttle body/ intake setup, exhaust, etc.... Which engine would your prefer?

Me personally, I love the m30 engine. The s38 is a wonderful engine but it has to be slapped around alittle before it slaps back. The m30 sets it off and slaps first. Other reasons being i can get satisfying power out of a m30 without the maintainance and cost headache of the s38.

Even tho i have had e28 535's with bolt ons that would give a stock e28 m5 a good run i dont know what a m30b35 in a e28 body feels like so i cant comment on what the 2 motors in the same body would feel like. I feel given the same exhaust, intake, etc the m30 may outperform the s38 but knowing the advantages of a dohc raises some conflicts in my thoughts.

So there it is. Chime in, tell your opinions and facts. Sorry if this a rethread.

My modified M30 even untuned puts out nearly as much power as a US spec S38B35. Of course it's nowhere near the S38B36 or S38B38 though. I would love to put my engine in an E28 though...

Geez... that's twice in a week I got schooled on ///M cars.

I think the b35 is great but i would like some more top end. Im still in the process of getting a new intake made to hopefully help me along...only the dyno will tell...*Hint* (CNC machining and CF will be involved...oh, and ill probably slap a 90mm tb on too :buttrock)

M30 s38 ITBs FTW

Boost the M30. DOHC is for suckas..:D


How easily can you fit S38 ITBs to an M30?

How easily can you fit S38 ITBs to an M30?
Its very easy. I have never seen it done but was thinking of doing it to my m30. Since my m30 is sitting in a e30 chassis there wont be enough room to clear the brake booster. I will be developing my own intake system instead.

But that raises another question. Like i said i have never seen a m30 with itb's. With stock heads, will a m30 match the s38 power if a set of s38 itb's and headers was installed? If not, then what if the m30's compression was raised to 10.5:1?

My modified M30 even untuned puts out nearly as much power as a US spec S38B35. Of course it's nowhere near the S38B36 or S38B38 though. I would love to put my engine in an E28 though...You have alot of work done to your motor. The s38 doesnt get peak power gaines from bolt on parts but if you start porting and swaping cams and such you will see yourself over 300 chp quite easy. Thats 1 reason i only mentioned a stock s38. The m30's can not match the s38 upgrade for upgrade.

BTW to get 3.6 liters, did you use the crank from a 77 3.3? I heard i can use the crank from a s38b38 to get 3.8 liter in a m30 but was later on told its not true.

mmmmm s38/m30 shorty intake.....:D


http://i215.photobucket.com/albums/cc101/Goathumper/M5IM1.jpg


http://i215.photobucket.com/albums/cc101/Goathumper/M5IM2.jpg

Its very easy. I have never seen it done but was thinking of doing it to my m30. Since my m30 is sitting in a e30 chassis there wont be enough room to clear the brake booster. I will be developing my own intake system instead.

But that raises another question. Like i said i have never seen a m30 with itb's. With stock heads, will a m30 match the s38 power if a set of s38 itb's and headers was installed? If not, then what if the m30's compression was raised to 10.5:1?

ITBs don't add power, just throttle response. + they sound and look cool :cool

I believe 260(crank) bhp is pretty much the limit of a conservatively tuned high compression M30B35 before you add a wild cam, lose some driveabilty and modify the rockers for a higher rev limit.

ITBs don't add power, just throttle response. + they sound and look cool :cool

I believe 260(crank) bhp is pretty much the limit of a conservatively tuned high compression M30B35 before you add a wild cam, lose some driveabilty and modify the rockers for a higher rev limit.
Thats interesting. So i guess the answer would be yes it can. Have you seen dyno sheets or going off of experience and theory? I know a number of built m30's but thats with porting, cams, hc, etc that claim to be close to 300 crank but no dynos. Only guesstimation. I think adding itb's would add hp on the m30 simply because the stock intake is so restrictive but it might reduce low end torque do to the shorter runners but i dont know.

DOHC of bust, seriously.

Its very easy. I have never seen it done but was thinking of doing it to my m30. Since my m30 is sitting in a e30 chassis there wont be enough room to clear the brake booster. I will be developing my own intake system instead.

But that raises another question. Like i said i have never seen a m30 with itb's. With stock heads, will a m30 match the s38 power if a set of s38 itb's and headers was installed? If not, then what if the m30's compression was raised to 10.5:1?

How is it easy? Please let me know what way cause the way I am doing it is not easy. Are you talking machining adapters or cutting and welding the stock m30 runners to the s38 ITB's?

:buttrockThats interesting. So i guess the answer would be yes it can. Have you seen dyno sheets or going off of experience and theory? I know a number of built m30's but thats with porting, cams, hc, etc that claim to be close to 300 crank but no dynos. Only guesstimation. I think adding itb's would add hp on the m30 simply because the stock intake is so restrictive but it might reduce low end torque do to the shorter runners but i dont know.

I think Redfive on here got 212rwhp with a metric mechanic built engine, headers, MAF, port polish the whole works was a bit dissapointed then got himseld boost. But I believe N/A he didnt get a wild cam because he didnt want to lose low end driveability on the street.

Hari with his built engine will probably get a bit better once fully tuned going off his baseline dyno.

Alpina got 260 crank bhp with their high compression (non turbo) B10 M30.

Its not the intake thats the restrictive part of the M30, its the oldskool cylinder head.

12 valve SOHC :buttrock

With a full race built engine 300rwhp is probably easy if you modify everything but doesnt that money spent defeat the whole point of wanting something reliable bang for buck :confused

M30 is a great daily driver with grunt low down but chokes at the top of the rpm range, even if you could stay up there you need new rocker arms and stuff.
S38 has a narrower power band at the top end.

In my opinion the M30 is a poor mans S38 :confused Yeah I can afford an M5 i just don't want to pay the xtra $$$ to keep her nice.

I built one. Bavarian engine exchange performance package, M30b35, blueprinted, balanced ported and polished, 274 cam, Dinan intake, MAF, headers, exhaust, custom tuning by autothority. The end result 210rwhp/180rwtq. With a bigger bore, stroker crank, and hotter cam you might push up into the 250-260 range. I've heard of race only engines that produce 300rwhp, but they have short lives.
The end result was not worth the money invested. I was ulimately disappointed. I could have done better swapping in a s52.



from Justin (redfive)

Ok guys here is my 2 cents. The m30 is a great engine and in my opinion is best when lightly turbocharged, trying to get the engine to perform even like the US S38B35 with mods is going to cost too much and defeat the purpose of the m30 reliability, drivability, and maintainability.

Increasing power on the m30 naturally aspirated is not going to be easy or cost effective you have too many restrictions most of all the head. You cant make the m30 have its low end power and a substantial increase in peak power unless you do some pretty fancy engineering. Building a custom intake plenum like the one you showed goathumper while cool is a bad idea as your going to lose the low speed cylinder filling and resonance that the stock intake manifold provides (the s38b35 proves this with its gutless feel because its tuned for high rpm peak power with short fat intake trumpets that’s why BMW went through the trouble on the s38b36 and b38 with the variable resonance intake system with switch points (they also use variable resonance and double VANOS and valvetronic (not on Ms yet) on the newer engines to maintain power throughout the complete power band)). If you want to improve on this area save your self a lot of money and time and send your stock manifold off to be extrude honed its proven to make good broad power increases (area under the curve!) and also have your throttle body bored for a little more “response” and flow. I would also look at doing a MAF conversion as the AFM is a major restriction and you usually gain either a chip (Miller) or a variable air/fuel ratio controller (Split Second). The last thing I would do would be doing a moderate performance cam to increase top end performance while maintaining low rpm grunt. This wont give massive power numbers but if setup correctly with the correct gearing and selective lightening (flywheel, maybe seats (Recaro Sportster CS FTW!) carbon fiber hood (PAINT IT LOL and no pin on unless it’s a race car) and maybe some sound deadening gone) you will have a fun RELIABLE car especially if you’ve taken care of the brakes and suspension prior. If you want more power its simple do all of the above minus maybe the cam and get yourself a turbo kit and then all you have to worry about is maintenance assuming the stock engine is in good repair. Again just my opinion!

How is it easy? Please let me know what way cause the way I am doing it is not easy. Are you talking machining adapters or cutting and welding the stock m30 runners to the s38 ITB's?
I beleive the m30 and s38 have the same gap between ports. Im not sure but if so, i would rather fabricate the flangs instead of using m30 flangs.

:buttrock

I think Redfive on here got 212rwhp with a metric mechanic built engine, headers, MAF, port polish the whole works was a bit dissapointed then got himseld boost. But I believe N/A he didnt get a wild cam because he didnt want to lose low end driveability on the street.

Hari with his built engine will probably get a bit better once fully tuned going off his baseline dyno.

Alpina got 260 crank bhp with their high compression (non turbo) B10 M30.

Its not the intake thats the restrictive part of the M30, its the oldskool cylinder head.

12 valve SOHC :buttrock

With a full race built engine 300rwhp is probably easy if you modify everything but doesnt that money spent defeat the whole point of wanting something reliable bang for buck :confused

M30 is a great daily driver with grunt low down but chokes at the top of the rpm range, even if you could stay up there you need new rocker arms and stuff.
S38 has a narrower power band at the top end.

In my opinion the M30 is a poor mans S38 :confused Yeah I can afford an M5 i just don't want to pay the xtra $$$ to keep her nice.
I thought of the alpina but i dont know what all went into it. The m30 intake is pretty restrictive. First thing the air does when entering is hit a wall then with all the turns after. Its like the difference between a str8 through exhaust and an exhaust that doesl loops. But the intake is also a big part of the m30's torque development. The head is actually pretty good. You can see straight through the valves into the cylinder much like the s38. Of course there is only 2 valves per cylinder which is a big restriction. Does anyone have flow charts for these 2 engines stock?

Ok guys here is my 2 cents. The m30 is a great engine and in my opinion is best when lightly turbocharged, trying to get the engine to perform even like the US S38B35 with mods is going to cost too much and defeat the purpose of the m30 reliability, drivability, and maintainability.

Increasing power on the m30 naturally aspirated is not going to be easy or cost effective you have too many restrictions most of all the head. You cant make the m30 have its low end power and a substantial increase in peak power unless you do some pretty fancy engineering. Building a custom intake plenum like the one you showed goathumper while cool is a bad idea as your going to lose the low speed cylinder filling and resonance that the stock intake manifold provides (the s38b35 proves this with its gutless feel because its tuned for high rpm peak power with short fat intake trumpets that’s why BMW went through the trouble on the s38b36 and b38 with the variable resonance intake system with switch points (they also use variable resonance and double VANOS and valvetronic (not on Ms yet) on the newer engines to maintain power throughout the complete power band)). If you want to improve on this area save your self a lot of money and time and send your stock manifold off to be extrude honed its proven to make good broad power increases (area under the curve!) and also have your throttle body bored for a little more “response” and flow. I would also look at doing a MAF conversion as the AFM is a major restriction and you usually gain either a chip (Miller) or a variable air/fuel ratio controller (Split Second). The last thing I would do would be doing a moderate performance cam to increase top end performance while maintaining low rpm grunt. This wont give massive power numbers but if setup correctly with the correct gearing and selective lightening (flywheel, maybe seats (Recaro Sportster CS FTW!) carbon fiber hood (PAINT IT LOL and no pin on unless it’s a race car) and maybe some sound deadening gone) you will have a fun RELIABLE car especially if you’ve taken care of the brakes and suspension prior. If you want more power its simple do all of the above minus maybe the cam and get yourself a turbo kit and then all you have to worry about is maintenance assuming the stock engine is in good repair. Again just my opinion!
Your opinion to me is right on target. I have had good results with the higher rpm with just opening up the exhaust with dual 2 1/4 pipes but the car was rediculously loud. Some people say cams on m30's when turbo'd dont really do much and you have to get a real test and trued port job or you may end up losing power.

A camshaft will help as long as its designed for the application, naturally aspirated cams dont work well due to the fact that they usually have more overlap and a few other factors. But a proper cam designed to work with turbos will be beneficial but the question has to be asked how much of a gain and what will it cost. The M30 intake manifold is perfect for what it does and if you go measure the length of the runners youll see why they went with that shape, again if you want to improve on the intake manifold extrude hone it! Either way this is a fun discussion!

True. I think i will go with a high lift cam and no porting when i turbo my car. I will also be fabricating a manifold for use in the higher rpm because all that low down power will be useless in my car.

Well I wouldnt change the manifold I mean Alpina didnt on the B10 Biturbo and if there was a gain they most likely would of done it they simply moved the throttle body so that it would be easier in terms air flow from the intercooler. Again your call and either way Id love to see what you come up with good luck!