Can an e28 (635csi) head be used on my e9? Are the ports truly larger? Will this affect my compression ratio?
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E28 heads
- Thread starter D Calkins
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What engine is it? E28 based E24s ("635 CSi") could mean M30B32 (the E28 based 633), M30B34 (mid '80s E24s), or M30B35 (late 80's E24s).
The M30B30 which is what is in most 3.0 E9s has an 89 mm bore, and a combustion chamber volume of 58 cc or about 64 cc (late Euro cars).
So and M30B32 head should be compatible as long as the cooling and oil passages are the same (not sure on that one).
The mid 80's M30B34, found in a lot of E24s, has a bore of 92 mm and a combustion chamber volume of 58 cc, so that "might" be compatible, with the same caveat about oil and cooling, but I am not sure what the different bore might mean at the head gasket end of things.
The M30B35 found on later E24s (87-89 IIRC) has a 65 cc combustion chamber and a bore of 92 mm, so that will lower your compression ratio, and also have the same caveat about oil and cooling, but I am not sure what the different bore might mean at the head gasket end of things.
Is your engine bad? Have you done a leak test?
The M30B30 which is what is in most 3.0 E9s has an 89 mm bore, and a combustion chamber volume of 58 cc or about 64 cc (late Euro cars).
So and M30B32 head should be compatible as long as the cooling and oil passages are the same (not sure on that one).
The mid 80's M30B34, found in a lot of E24s, has a bore of 92 mm and a combustion chamber volume of 58 cc, so that "might" be compatible, with the same caveat about oil and cooling, but I am not sure what the different bore might mean at the head gasket end of things.
The M30B35 found on later E24s (87-89 IIRC) has a 65 cc combustion chamber and a bore of 92 mm, so that will lower your compression ratio, and also have the same caveat about oil and cooling, but I am not sure what the different bore might mean at the head gasket end of things.
Is your engine bad? Have you done a leak test?
You don’t want a b35 head on your b30, there re no cheap swaps to improve power.
A lot to digest here. The e28 is a sedan and had the M20, B32, B34, and the multivalve motors. I’d never had a B35.
A 635csi is an e24. The 635 only had the B35 in 1989. Check to see if it is actually a B35.
B34 Head:
A good upgrade. Less prone to cracking than very early B28/B30 heads. The 264 cam sucks though so if you swap heads keep your old 272 cam.
B35 Head. It’s a great head and flows better. Bigger ports and bigger valves. The cam is better also, I want to say it is a 272 also but obviously that is only one spec and it’s tuned for factory fuel injection.
If you drop a B35 head onto a B34 you lose compression. You can’t really do a B35 head without also getting new pistons, which is why @HB Chris said it wasn’t a cheap/good upgrade. If you need custom pistons anyway, it’s a good route to go IMO.
Another thing to note as you swap heads, you will need the dual row timing chain and the old timing cover. Said timing cover should match the deck height of the head. That could mean finding a timing cover with more material left on it, or decking it at the same time as your head.
Disclaimer: I’m not a motor expert and Ive only taken m30’s apart, not back together.
A 635csi is an e24. The 635 only had the B35 in 1989. Check to see if it is actually a B35.
B34 Head:
A good upgrade. Less prone to cracking than very early B28/B30 heads. The 264 cam sucks though so if you swap heads keep your old 272 cam.
B35 Head. It’s a great head and flows better. Bigger ports and bigger valves. The cam is better also, I want to say it is a 272 also but obviously that is only one spec and it’s tuned for factory fuel injection.
If you drop a B35 head onto a B34 you lose compression. You can’t really do a B35 head without also getting new pistons, which is why @HB Chris said it wasn’t a cheap/good upgrade. If you need custom pistons anyway, it’s a good route to go IMO.
Another thing to note as you swap heads, you will need the dual row timing chain and the old timing cover. Said timing cover should match the deck height of the head. That could mean finding a timing cover with more material left on it, or decking it at the same time as your head.
Disclaimer: I’m not a motor expert and Ive only taken m30’s apart, not back together.
The heads are b35
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Yup that’s a B35 heads. I you look around you can probably find a whole M30B35 for $500.
While B35 donor cars are abundant and financially cheap, at least if you're near a metropolitan area, I'll still agree with Chris by adding that there are no emotionally cheap swaps to improve power.
I've been tempted by a half dozen B35 (and even M106!) donor cars for ~$1k, but the hassle of either 1) parting out the car or 2) getting the rest of it to a junkyard to legally relinquish can be a bit of a chore.
Maybe I'm just short on time these days! I suppose 20 year old me would look at that as an adventure rather than a hassle.
One thing we don’t see a lot of is carbed B35’s. Not to downplay carb tuning, but I think a major factor in B35 engine swap is the move to FI. Unless you leave the motor bone stock, the FI scope creep requires an equal if not more amount of tuning. Meanwhile, think about all of the rednecks dropping carbed 302’s into a pickup truck in a weekend.