M20 885 Cylinder Head w single valve spring

[Motorsport1207]

Measured both cams i (K) cam and the SETA. Both lobe circle is similar 1.094 - 1.100. Both lobe heights are the same. 1.360- 1.369. lThe duration on the SETA cam is much shorter. See pic. Don,t really see a need for the SETA cam. I am just going to convert this 885 head with dual valve springs and a “K” cam. Sent from my iPhone using Tapatalk

[digger]

Max power with 2.7i: 145whp, 145wtq

Changed the intake from 325i to 325e, added 325i TB and ground TB to "i"spec, 145whp, 170wtq.

Fresh m20b25 ready for spec class, 169whp, 159wtq.

2.7 crank, "i"pistons, stock cam : 180whp


You know me, Digger.....

i was more talking about a single variable, say take a bone stock ETA (or SETA) throwing in the "B25" cam or Alpina Cam (with valve springs) without the different intake/TB etc i dont think you are losing much torque with the additional duration as it is still fairly mild.

[ForcedFirebird]

yes, i mean good trapped mass/VE at higher rpm. An eta cammed engine is hardly a torque monster havent seen a dyno of one for many years.

Max power with 2.7i: 145whp, 145wtq

Changed the intake from 325i to 325e, added 325i TB and ground TB to "i"spec, 145whp, 170wtq.

Fresh m20b25 ready for spec class, 169whp, 159wtq.

2.7 crank, "i"pistons, stock cam : 180whp


You know me, Digger.....

[digger]

Trapped mass is a tricky subject. To say "junk for power" is subjective if you include torque lol. Trapping mass helps get things moving, but they fizzle out up top. :/

digger
I am surprised the seta and eta have the exact lobes - was it only the bearing count that's different?

yes, i mean good trapped mass/VE at higher rpm. An eta cammed engine is hardly a torque monster havent seen a dyno of one for many years. its probably more for fuel efficiency and part throttle

I'm not sure if they are the exact same lobes, my only involvement in that graph was supplying the Alpina cam

[ForcedFirebird]

but the duration is very small thats why it is junk for power.

Trapped mass is a tricky subject. To say "junk for power" is subjective if you include torque lol. Trapping mass helps get things moving, but they fizzle out up top. :/

digger
I am surprised the seta and eta have the exact lobes - was it only the bearing count that's different?

[digger]

Maybe I don’t understand, but if the SETA cam has less lift - how can it be re grounded to be a performance camshaft. I thought the performance camshaft would have a higher lift and duration to allow more air into the chamber. Thanks Sent from my iPhone using Tapatalk

The SETA cam has a bit more lift than the B25 cam based on data i've seen but the duration is very small thats why it is junk for power. You can perhaps theoretically regrind by reducing the basecircle and some do hard weld grinds but there are better roads to go down

[Motorsport1207]

Re-read my post. I said the seta cam has less lift, so it cannot be reground. Also, from your original post; Your 885 seta head clearly has 7 cam bearings. It also clearly has all 7 drilled for oil passages to the bearings. To convert that to a b25 head, you'll need dual valve springs and the "k" cam mentioned by ForcedFirebird. If you're putting in a new (or reground) cam, you should either resurface your rockers or replace them so that the hardened pads are square to the new cam.

Ok Thanks, I did not catch that. Sent from my iPhone using Tapatalk

[McGyver]

Maybe I don’t understand, but if the SETA cam has less lift - how can it be re grounded to be a performance camshaft. I thought the performance camshaft would have a higher lift and duration to allow more air into the chamber. Thanks Sent from my iPhone using Tapatalk

Re-read my post. I said the seta cam has less lift, so it cannot be reground.

Also, from your original post; Your 885 seta head clearly has 7 cam bearings. It also clearly has all 7 drilled for oil passages to the bearings. To convert that to a b25 head, you'll need dual valve springs and the "k" cam mentioned by ForcedFirebird. If you're putting in a new (or reground) cam, you should either resurface your rockers or replace them so that the hardened pads are square to the new cam.

[Motorsport1207]

There's a white "K" painted on a stock 325i cam.

Ok thanks. I will look for that Sent from my iPhone using Tapatalk

[ForcedFirebird]

There's a white "K" painted on a stock 325i cam.

[Motorsport1207]

I can help with this, might have done an m20 head, or two, hehe. 885 heads came with single springs in 1988 only. As mentioned, just add inner springs, change the cam to the "k" cam and be done with it. The castings themselves are identical. I have never heard of, or seen a 4 bearing 885 head. A member on e30tech years ago posted about one, but AFAIK they are all 7 bearings and have a unique 88-only eta 7 bearing cam. I have converted 200 head to use b25 cams, simple process, just have to angle drill the passages. Never measured a seta cam, but to the eye, it appears closer to the eta than b25 cam with it's pointy lobes (shorter duration). The seta had 8.5:1 compression, b25 8.8:1 and eta 9:1 - so, cams would be different in OEM applications.

Thanks for the good information. So basically the SETA head was a low performance vs the 325i. The SETA cam is less cam lift as compared to the 325i. I have the camshafts and both heads. I will take a few pics and measure the cam lobes. Also what do you mean by “K” camshaft. Thanks Sent from my iPhone using Tapatalk

[Motorsport1207]

The m20b25 885 head and the seta 885 head have different cam profiles. I believe the seta cam has less lift, meaning it can't be reground to use as a high performance b25 cam. I've also heard that there are differences in how many cam bearings have oil journals. I have both 885 heads sitting in a box, so I guess I could go measure stuff... more info: https://www.r3vlimited.com/board/for...-answer-please Ask Matt for more info: MR 325

Maybe I don’t understand, but if the SETA cam has less lift - how can it be re grounded to be a performance camshaft. I thought the performance camshaft would have a higher lift and duration to allow more air into the chamber. Thanks Sent from my iPhone using Tapatalk

[digger]

there is definitely no 4 "bearing" 885, maybe they put a 4 journal cam into the 7 "bearing" head with a different machining applied to the casting. The bare head part numbers are the .different between the 325i and SETA which could be a machining difference applied to the same 885 casting p/n.

The easiest ways is to post pics of the top of the head to show the oil drillings or compare to a m20b25 head.

the SETA barely made more ponys than the regular ETA so the cam must be as weak as the proverbial even though it was hamstrung with a lower CR.....

[ForcedFirebird]

I can help with this, might have done an m20 head, or two, hehe.

885 heads came with single springs in 1988 only. As mentioned, just add inner springs, change the cam to the "k" cam and be done with it. The castings themselves are identical.

I have never heard of, or seen a 4 bearing 885 head. A member on e30tech years ago posted about one, but AFAIK they are all 7 bearings and have a unique 88-only eta 7 bearing cam.

I have converted 200 head to use b25 cams, simple process, just have to angle drill the passages. Never measured a seta cam, but to the eye, it appears closer to the eta than b25 cam with it's pointy lobes (shorter duration). The seta had 8.5:1 compression, b25 8.8:1 and eta 9:1 - so, cams would be different in OEM applications.

[McGyver]

The m20b25 885 head and the seta 885 head have different cam profiles. I believe the seta cam has less lift, meaning it can't be reground to use as a high performance b25 cam.

I've also heard that there are differences in how many cam bearings have oil journals.

I have both 885 heads sitting in a box, so I guess I could go measure stuff...

more info:

https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m20/274267-885-i-vs-885-seta-strait-answer-please

Ask Matt for more info: MR 325