2.8L stroker questions......

[Noshow20x96]

Hey everyone. Just got some questions about this build that I'm going to be doing.

I currently have a 01/87 325e eta and I'm going to get a complete 91 vert 325i motor, harness/wires. Also getting a 98 vert M52 2.8l crank.

So I'm going to put the crank in the eta block, use the eta rods, (130 mm) the 325i pistons and 325i head. (885) Now I know I have to make that spacer for the nose of the m52 crank (also would like to know about the specs on that)

Now I know some builds had to shave down the counter weights on the crank about .25" just to clear the piston skirt and then get it balance.

Also questions on what the compression ratio would be- what tune should I use, (I'm going to convert with the 173 electronics) what cam should I use? And what other upgrades I need to do??? Cam gear, rocker arms, ect ect

Just trying to find a guide line of what to do.

Read some threads on this build and so far found some awesome info, and also some negative feed on it as well.

This is going to be a street car that I would like to take on the track- road course/drifting.

Thanks for the help if you can. This would be a great guide line for me to complete this build.

[ak-]

A stand alone ecu like MegaSquirt to get the most out of your build and add on's or get the stock 173 reflashed at a dyno tuner who can do it.

[Noshow20x96]

Now I know that the war chip and maf conversation is also a pretty good tune for the m20 motor but I just read that it isn't really good. Some guys are having a hard time tuning it cuz they can't get windows xp.

[digger]

Now I know that the war chip and maf conversation is also a pretty good tune for the m20 motor but I just read that it isn't really good. Some guys are having a hard time tuning it cuz they can't get windows xp.

thats a cop out mate, ive not used warchip but even here you can get an old laptop for tuning for peanuts.

[digger]

CR will be 9.7:1 if you maintain the same piston position relative to deck. this typically involves removing 0.5 mm (nominally) from the top of the block. i would aim for about 1.0 to 1.2mm clearance between the angles squish between head and piston

you can run a stock cam, schrick 272, schrick 284/272 or even a 288 if you verify the piston to valve clearance. 288 is getting a bit large for the CR ideally you would want 10.5:1 CR to run a 288 cam to reduce the doughines off cam. i recommend an adjustable cam gear, IE HD rockers

[Cinnabar325is]

I'm running this setup in my car. I'd do a few things differently the second time around, but it's a good basic formula. I didn't take anything off the block, so the CR on mine is ~9.3:1. I'm running a Cat Cams 298* cam that came with the car and I figured I'd try it out. Checked to make sure the valve to piston clearance was okay and went with it. As digger said, the cam is too big for the CR, it is quite soft down low. Also, running the Miller MAF conversion, long tube headers... etc.

Was about 0.25" off the counterweights. No interference issues with the intermediate shaft, however, as many people said there would be.

[digger]

I'm running this setup in my car. I'd do a few things differently the second time around, but it's a good basic formula. I didn't take anything off the block, so the CR on mine is ~9.3:1. I'm running a Cat Cams 298* cam that came with the car and I figured I'd try it out. Checked to make sure the valve to piston clearance was okay and went with it. As digger said, the cam is too big for the CR, it is quite soft down low. Also, running the Miller MAF conversion, long tube headers... etc.

Was about 0.25" off the counterweights. No interference issues with the intermediate shaft, however, as many people said there would be.

catcams are soft down low in general. advancing the cam 6 degrees helps alot and you dont lose the topend either. i suspect the LSA on catcams are wider than they say all the strokers with catcams have soft bottom ends and i have seen probably 6 or 7 dynos of 2.7, 2.8 or 3L. i would choose schrick unless a racecar

[Cinnabar325is]

catcams are soft down low in general. advancing the cam 6 degrees helps alot and you dont lose the topend either. i suspect the LSA on catcams are wider than they say all the strokers with catcams have soft bottom ends and i have seen probably 6 or 7 dynos of 2.7, 2.8 or 3L. i would choose schrick unless a racecar

Interesting. I do have an adjustable cam gear, but have not played much with it. My worry was piston to valve clearance, which I don't have any real measurement of. I believe advancing the timing would increase the chance of an intake valve collision, correct?

[digger]

Interesting. I do have an adjustable cam gear, but have not played much with it. My worry was piston to valve clearance, which I don't have any real measurement of. I believe advancing the timing would increase the chance of an intake valve collision, correct?

yes it gets closer, you can make a tool to help press the valves down with the valve cover off. do it at TDC and various increments after. this will tell you vertical clearance but wont tell much about radial clearance which is likely ok with stock valve diameter and pistons. i did it this way on mine and didnt have a problem but it is potentially risky

[Noshow20x96]

Ok. I have a couple questions for you guys. It seems like if I take .25mm of head/block my CR would be around 9.5:1 now I've been seeing guys taking material off the block instead of the head... Is that because to keep the same combustion camber in the head? Also to my knowledge if I go with a 288 cam it would seem like I would need to go to ITBs to get the full potential of the cam. It seems like it I go with a 284/272 I would have my valve clearance and have a pretty aggressive cam for the motor. What do you guys think?

And this info is helping me out a lot. Very intelligent people on here.

[nando]

9.5:1 isn't enough for a 288 cam, and it will have severe piston/valve contact issues with the stock pistons anyway, that will only be made worse with shaving the head/block.

even the 284/272 is pushing it. if you must use stock pistons, your best bet is the schrick 272. that will work well with a 9.5:1 CR if that's what you actually end up with.

my feelings -
9:1 up to 10:1 - 272
10:1-10.5:1 - 284/272
10.5:1 and higher - 288
race motor with insane everything - 304 :D

[Noshow20x96]

ok, that clears up my mind for what cam to use to what CR you have...

I would like to keep stock components if I can with this build.

[digger]

if you use a 288 in a lower comp engine it would be a bit of a dog down low and annoying on the street but would still make more power in a peaky manner which would be ok for a track engine where you drive in a relatively narrow band 4k upwards. for any sort of street driving going for smaller duration is better for a more useable performance and crisper response. if you look at what alpina did with the duration they used which was less than the schrick 272 with a ported head and header it is pretty good and has heaps of bottom end and midrange

270 vs 288 cam


getting rid of the cast intake manifold will still help utilise even a milder cam

[Noshow20x96]

Ok. Now my next question is what performance cam brands would be best for the bang of the buck. Now I know that schrick cams are one of the best. Now what do you guys think of camko cams for the m20 motors. I have a deal with a guy that I can get a 272 for $400 BMIB.

[Ray Smoodiver]

if you look at what alpina did with the duration they used which was less than the schrick 272 with a ported head and header it is pretty good and has heaps of bottom end and midrange

270 vs 288 cam


getting rid of the cast intake manifold will still help utilise even a milder cam

Is that with regards to the Alpina 276 cam? Do you know the duration?