Another 2.7 Stroker Question

[SDemetris]

Hey. I just bought my e30 last week so sorry for my ignorance. But I was looking into putting an i head on my eta. Ive read its a bad idea to keep my stock pistons and just slap the i head on it because the compression ratio will be too low. To solve that, couldn't I just shave down the head a bit? Or would there be interference between the valve and piston if I did that? Thanks in advance for your help.

[digger]

it wont really "solve" the issues of low CR or having non matched piston crown and combustion chamber so i doubt it will make a bigh difference but it might help slightly. cant comment on P to V with this combo not checked that myself.

swapping a freshened head (not a junkyard one) is worth doing, if you do the swap

[Gary Horneck]

Just slap a good i head, harness and sensors. Don't worry about the compression ratio. My 2.7i is a torque monster. Shocking difference, especially with cam and headers. My car ran .5 seconds behind a LS1 Miata all day, and 2 seconds in front of the rest of the class. It moves.

[SDemetris]

ok thanks guys. I think that when i eventually do this, i will probably keep my pistons as I dont have much experience inside the actual engine. everything else i can handle.. Any idea where i can get measurements on how much i can mill down the head? I can do that myself as i have access to a machine shop, but i need to know what will be safe

[nando]

Just slap a good i head, harness and sensors. Don't worry about the compression ratio. My 2.7i is a torque monster. Shocking difference, especially with cam and headers. My car ran .5 seconds behind a LS1 Miata all day, and 2 seconds in front of the rest of the class. It moves.

have you dyno'd it? because none of the 2.7i's I've seen have been very impressive. "torque monster" seems to mean stock eta torque levels, almost as much power as a stock M20B25. yours could be different, just wondering.

[Regnar75]

i have never dyno'd mine but even with the 2.93lsd it was noticeably quicker than my buddies 325i (both he and i thought so) but no dyno yet. there is some decent torque out of it, and top end is very nice, but its a huge improvement over an eta at least

[timmyr77]

2.7i is definetly a big improvement of a b25. I lightened the flywheel on mine, no ac, chipped and head shaved .27mm. Torque improved a lot. Just to compare, I pull on my cousins m50 swapped coupe in my heavier vert.

[timmyr77]

And you won't have valve piston contact if you don't mill off more then .25mm or so. If you want to go further, then you can buy a adjustable cam gear from bimmerheads to fix that issue.

A lot if people advice agains a 2.7 build but if you do it right the first time it is definetly worth it. (Keep in mind I completely rebuilt the head and block) a fresh head and block will make a big difference as well.

[Gary Horneck]

I call it torque monster, so do the people that watch me autox it every month. Any 26 yr old, N/A car that can place in the top 6 RAW times out of a field of 85 cars is a torque monster in my book.

[nando]

ass dyno ftw :p

[digger]

reminds me of a saying i heard once, " when they cant make hp they start talking about torque....."

[Gary Horneck]

Autocross/Rallycross results FTW ;D Only an ass rely's on Dyno data to strut one's stuff.

[SDemetris]

.25mm? That's not even worth doing? And how is an adjustable cam gear gonna help?

[nando]

Autocross/Rallycross results FTW ;D Only an ass rely's on Dyno data to strut one's stuff.

yeah, who needs a dyno test to verify the benefits of engine mods? ;)

[digger]

yeah, who needs a dyno test to verify the benefits of engine mods? ;)

because engine is the most important aspect of setup for autoX? ;)

honestly for low speed racing a shorter diff does what you need but you get found out on a high speed circuit