731 vs 885 head swap

[digger]

731 = 264' duration 6.58mm lift

885 = 256' duration 10.1mm lift

this is garbage i dont know how anyone can think that these are correct..........

http://www.e30tech.com/forum/showthread.php?t=108802

[pantelones]

this is garbage i dont know how anyone can think that these are correct..........

http://www.e30tech.com/forum/showthread.php?t=108802

Thank you for correcting that. I had those number written down in my notes. I believe they were taken from this thread....

http://www.e30tech.com/forum/showthread.php?t=52085

I'm not sure how I missed your thread about cam profiles. I was researching that about 6 months ago when I was looking to rebuild my head while the motor was out.

[e30leigh]

that wil teach me for assuming those other numbers were correct.

thanks for the link digger. very interesting.

id love to see the shrick 288 against the vac turbo cam.

[AlexKing]

Is there much differance in performance using a decked head compared to one that isn't?

[digger]

Is there much differance in performance using a decked head compared to one that isn't?

no, it might be a few % at best

when you start adding performance cams to engines that start off at low CR like the B25 etc then it becomes more worthwhile

[digger]

Thank you for correcting that. I had those number written down in my notes. I believe they were taken from this thread....

http://www.e30tech.com/forum/showthread.php?t=52085

I'm not sure how I missed your thread about cam profiles. I was researching that about 6 months ago when I was looking to rebuild my head while the motor was out.

to be fair i will clarify and say that the 731 number is most likely the cam lift and the 885 is the valve lift so the numbers could infact be close but it is not a logical comparison because one is at the cam and the other at the valve and the rocker ratio is not included

[UserError]

to be fair i will clarify and say that the 731 number is most likely the cam lift and the 885 is the valve lift

731 and 885 have nothing to do with the cams, they're different M20 head castings.

200 = 325e
731 = 323i
885 = 325i

[pantelones]

it is not a logical comparison because one is at the cam and the other at the valve and the rocker ratio is not included

This I have not taken into consideration. I think I overlooked it when I was writing it down and just saw lift. Strange that they would change that on only one of the cams.

731 and 885 have nothing to do with the cams, they're different M20 head castings.

200 = 325e
731 = 323i
885 = 325i

User error indeed..... What about the cam in the head smart guy?

[UserError]

Nothing really stopping you from putting a 323i cam in a 325i head, since they'll physically fit. For that matter, if you drill oil holes for the cam bearings in an eta (200) head, you can put a 7 bearing cam in one of those, as well. The real point was that from his response, it read as if digger was saying that the number 731 had to do with the lift at the cam, and 885 was the lift at the valve, which is not true in the slightest. Rereading it again, I could see an alternative interpretation, so cheers!

[pantelones]

Nothing really stopping you from putting a 323i cam in a 325i head, since they'll physically fit. For that matter, if you drill oil holes for the cam bearings in an eta (200) head, you can put a 7 bearing cam in one of those, as well. The real point was that from his response, it read as if digger was saying that the number 731 had to do with the lift at the cam, and 885 was the lift at the valve, which is not true in the slightest. Rereading it again, I could see an alternative interpretation, so cheers!

I see what you are saying.....

I posted the following numbers

731 = 264' duration 6.58mm lift

885 = 256' duration 10.1mm lift

Those number are in fact wrong. The 731 was cam lift, and the 885 was valve lift (I believe the durations are about right?). Comparing the two is just silly, hence why he called me out on it. I misread the specs and wrote them down in my notes as both being valve lift.

[digger]

Nothing really stopping you from putting a 323i cam in a 325i head, since they'll physically fit. For that matter, if you drill oil holes for the cam bearings in an eta (200) head, you can put a 7 bearing cam in one of those, as well. The real point was that from his response, it read as if digger was saying that the number 731 had to do with the lift at the cam, and 885 was the lift at the valve, which is not true in the slightest. Rereading it again, I could see an alternative interpretation, so cheers!

i responded to the post where it referred to 731 and 885 and continued to used it in that context, my bad for not mentioning that the 731 actually refferred to B23 and 885 the B25. I have pulled apart many of the three variants and plotted out various cams so i am aware of the differences but should have been specific.........

[digger]

731 and 885 have nothing to do with the cams, they're different M20 head castings.

200 = 325e
731 = 323i
885 = 325i

even that is still only part of the story there is a B23 cam found in a 200 head (E21 323i) and the B20 cam found in a 731 (E30 320i) so we all should be more specific.