m90 piston and cam suggestions
- Thread starter posix
- Start date
OEM ones are pretty expensive : https://www.ecstuning.com/b-genuine-bmw-parts/piston-euro/11251278110/
so i have been considering CP pistons and rods
so i have been considering CP pistons and rods
Was there a reason to not rebuild/reuse the rods?
I am rebuilding my M90 at present. I have priced pistons and the going rate is about $1100 for forged made to order, with wrist pins and rings, mine at 10:1 compression ratio . There is no reason not to use the original rods. My cam has been reground to 284 specs. The head has been ported and port matched. I am running Motronic 1.0 injection open loop and a full 2" Billy boat exhaust system. I have had the engine running as such, but due to a good screwing by a "bad" engine builder am being rebuilt again after 20 minutes run time, so I am well aware of the costs and what will work for me. If the car won't perform to the level I expect, I will convert to Motronic 1.3 and have Mark D'Silva make a chip for it. Also, this time around I will use Diamond Racing Pistons. I found them searching around and they were rated equal to JE I later found out they are owned by the same parent company. The original reason for using them is JE wanted 2 months to produce a set and Diamond 3 weeks.
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Are the pistons bad or do you need to go over size? I would wait for the machinist to advise what is needed, and rods can be reused. If you are trying to bump the CR be aware of fuel requirements.
I am using custom 92.5mm pistons at 10.5:1 and cam.
Manufacturer has retired. Right Don?
I have used CP pistons in my S38 M5 motor at 11:1.
They have over 50k on them.
They also make Carillo rods so you could get the whole setup.
In my M30 motor I used stock rods but did a lot of extra material removal. See photo.
They are very strong and very heavy as stock.
I removed material and weighed them all to get them the same weight to the gram and then my machinist balanced all reciprocating parts including the harmonic balancer and flywheel.
Manufacturer has retired. Right Don?
I have used CP pistons in my S38 M5 motor at 11:1.
They have over 50k on them.
They also make Carillo rods so you could get the whole setup.
In my M30 motor I used stock rods but did a lot of extra material removal. See photo.
They are very strong and very heavy as stock.
I removed material and weighed them all to get them the same weight to the gram and then my machinist balanced all reciprocating parts including the harmonic balancer and flywheel.
FYI- CP piston sets on Sale at VAC. Just got this morning.
store.vacmotorsports.com
CP-Carrillo Forged Piston Set, BMW M30
Crank Type: B30; B34; B35. Bore Size: 89 mm; 89.5 mm; 90 mm; 90.5 mm; 91 mm; 91.5 mm. Compression Ratio: 8.5:1; 9:1; 9.5:1; 10:1; 10.5:1; 11:1.
92 bore?
piano top pistons?
what date is on your block?
call me....
piano top pistons?
what date is on your block?
call me....
does VAC also sell the rods? couldn't find it on their site.FYI- CP piston sets on Sale at VAC. Just got this morning.
CP-Carrillo Forged Piston Set, BMW M30
Crank Type: B30; B34; B35. Bore Size: 89 mm; 89.5 mm; 90 mm; 90.5 mm; 91 mm; 91.5 mm. Compression Ratio: 8.5:1; 9:1; 9.5:1; 10:1; 10.5:1; 11:1.
A question from an old hot rodder. In the day, we never went to high performance rods unless building a true "monster" motor. Why the concern here? Also. although compression ratio can be specified , whatever machining has been done to the head surfaces or the block deck itself have to enter into the measurements of the pistons and their dome height because of valve interference As I am sure Don will chime in, this is an exact science, and all these things have to be thrown into the equation. I guess if it is a stock unmolested engine and just needs to be bored, then there shouldn't be a problem?
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M30b34 euro spec engine
10:1 piano top pistons
92 mm
bore
1982 date on block and head
Wrong intake gaskets
10:1 piano top pistons
92 mm
1982 date on block and head
Wrong intake gaskets
Just trying to know the options
so I can update my costs document haha. At the end of the day I’ll go with what the machine shop saysJE 10:1 from my 81 M90. Either made wrong by JE or measured wrong by engine builder as the piston stuck up .5mm over the deck. It's hard to see as it is very small, but one of the valve was lightly touching the piston. So much for one of three best shops in town
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Just trying to know the options
Bobby - you should probably toss that cost spreadsheet right now. It's better you never know! Ignorance is bliss!
Strongly agree
