Why would the m20b25 have significantly higher revs than an m30b35 ? Aren't they basically the same engine design?
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Rama is developing a m30 itb kit which should help. It's still much harder to get lift though as it's a lower rocker ratio than the m20 so you need quite alot of duration which is not a good thing. The L/D for m20 is better
The m30 has much bigger cylinders than the m20 1.4 x yet the valves are only 5mm bigger iirc. It's the same reason why a m20 stroker doesn't rev as high as the smaller engines with same development the big cylinders use the available airflow at lower rpm
The m20 and m30 are vastly different, they both have 6 cylinders thoughLast edited by digger; 02-27-2018, 02:48 PM.89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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Originally posted by Bearmw View PostWhy would the m20b25 have significantly higher revs than an m30b35 ? Aren't they basically the same engine design?
WAT???
No, the M30 is an M10 with 2 more cylinders. It's a 1960's engine, with
huge diameter and width bearings, 100mm bore centers, a massive block, and a pretty advanced head-
for 1962.
The displacement was originally something like 2600, but it bored and
stroked out to 3500 by the end.
Different heads, too.
The M20 was the 'lightweight' economy engine. Smaller bearings all
around, narrower bore center, oil return external to the block (bitch tube)
and other economies. Like the dinky little cam oiler tube, unsupported in
the middle.
t
'respect your elders'now, sometimes I just mess with people. It's more entertaining that way. george graves
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Originally posted by LowR3V'in View Posti'm guessing the intake manifold.
maybe the port & head design?
it's basically the same, but not really. Should it rev as high as the m20? idk.
i try but it's not having it even with a "big" 294/273 cam
There's a reason basically all modern BMWs target a 500cc cylinder volume. Notice basically all BMW engines now are multiples of 500cc - 1.5l for 3 cylinders, 2.0 liters for the 4 cylinders (or less), 3l for 6 cylinders, 4l for 8 cylinders (S65), and 5l for 10 cylinders (S85). Where they go bigger the efficiency goes down.
Sorry to the M30 lovers but something like an M54 or an N52 makes more power and more torque, weighs less, and is more fuel efficient too. The M30 is just cool because it's old-school technology and you basically can't break it.
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Originally posted by nando View PostSorry to the M30 lovers but something like an M54 or an N52 makes more power and more torque, weighs less, and is more fuel efficient too. The M30 is just cool because it's old-school technology and you basically can't break it.89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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i agree the stock 8:00:1 M30 is a boat anchor mild spec (10.1:1 CR, cam, exhaust) m30 were circa 260bhp and 240lbft in the 80's on motronic. a bit more a rub here and there youd be able to beat that.
on the more extreme end i wanna see someone do a 4.0L m30 with RHD ITB, one of his roller rocker and cam combo89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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How is the M30 crank for harmonics? The M10 cranks are fine,
but they're 2 pots short.
Given that a 150 hp m10 is pretty mild, 225 bhp on a b30 seems pretty realistic.
And quite a bit more torque for a b35.
They also take more cam- 300 is still streetable, and the 314 in the racecar still idles
and pulls (albeit less impressively) from 2k.
t
who's still on an M54B30 kicknow, sometimes I just mess with people. It's more entertaining that way. george graves
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Originally posted by TobyB View PostHow is the M30 crank for harmonics? The M10 cranks are fine,
but they're 2 pots short.
Given that a 150 hp m10 is pretty mild, 225 bhp on a b30 seems pretty realistic.
And quite a bit more torque for a b35.
They also take more cam- 300 is still streetable, and the 314 in the racecar still idles
and pulls (albeit less impressively) from 2k.
t
who's still on an M54B30 kick
it has bigger rod bearings so there is a little more overlap in the journals but i think the length is a net downside
a 4V engine done properly always makes more topend but for a hot street engine that needs midrange torque the m30 would be pretty good
build on strengths i.e. dont go chasing peak hp with the m3089 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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Originally posted by digger View Posti agree the stock 8:00:1 M30 is a boat anchor mild spec (10.1:1 CR, cam, exhaust) m30 were circa 260bhp and 240lbft in the 80's on motronic. a bit more a rub here and there youd be able to beat that.
on the more extreme end i wanna see someone do a 4.0L m30 with RHD ITB, one of his roller rocker and cam combo
RHD is doing a roller cam and rockers for M30 now ?
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Idk but would not be hard to adapt cam profiles89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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