i'ed super-eta

[SpecM]

-Well guys Im new here, I hang out at bf.c but I'd like yalls opinion on a little project of mine.
-I have a 1988 325 super-eta and Id like to upgrade some parts ti b25i-spec. I will use a stock b25i cam, dual vave springs, 173 dme, and a 325i tach.
-Now... what else do I need to get this to work? Injecters? AFM?
-TIA guys.

[SpecM]

-Hello?

[Dave]

[SpecM]

-Yeah but all those threads are old and center on making stroker motors from b25i motors. I want to make a b27i from a super-eta.
-cam, springs, dme and m50 injecters. Sounds good?

[riverdale21]

The only problem with what you're suggesting is you wont get the horsepower you're hoping for with the restrictive "e" head. With the springs and cam you will be able to rev but if your head isn't flowing at the top end all those things wont amount to much. After reading that if you have the thought of just slapping on an i head and calling it a day that wont work either. The piston shapes are different for the e and i engines so you can't get the compression necessary for some horsepower.

There is no cheap way to build a stroker motor.

[nando]

The only problem with what you're suggesting is you wont get the horsepower you're hoping for with the restrictive "e" head. With the springs and cam you will be able to rev but if your head isn't flowing at the top end all those things wont amount to much. After reading that if you have the thought of just slapping on an i head and calling it a day that wont work either. The piston shapes are different for the e and i engines so you can't get the compression necessary for some horsepower.

There is no cheap way to build a stroker motor.

the 88 e head is exactly the same as the i head. how many times has this been stated now?

[riverdale21]

the 88 e head is exactly the same as the i head. how many times has this been stated now?

Nowhere that I have read on this forum.

[StereoInstaller1]

SpecM, PLEASE dyno your shit before and after, so we can all see what happens.
My '87 "is" is tired as hell...I wanna do a 2.7, and I bet I could find an '88 ETA block. We could make 327is badges! Woot!
Luke

[SpecM]

-Dyno it is, then. If anyone makes 327is badges, i want one!
-riverdale21, I dont like it when people online act like jerks so im going to be nice. My '88 eta HAS an b25i head on it, from the factory. ALL 1988 325/325e/528e have "super-etas" which have i heads, domed pistons so the CR doesn't drop too much, an i exhaust, 5300 redline and Motronic 1.1. The only restriction is the old-style "e" cam and single valvespring, which I plan to upgrade. Switch these parts over to b25i parts an 'viola, a 2.7i with only SLIGHTLY lower CR.
-You were correct in you last statment about cost, with the exception of super-etas.

[StereoInstaller1]

So it seems to me the solution is to start with a super ETA, re-spring, re-grind both the cam and valves, maybe shave a bit off the head to bump the CR back up...budget screamer!

Would that head (same as yours) require any machine work to add dual springs?

Luke

[SpecM]

-No, I think not. They just drop in place. Id like to buy another "i" head so I can rebuild and shave it without putting my car out of commition for a week or two, so if anyone has a b25 head, int manf, tb or m50 injectors lemme know.

[SpecM]

-How much can the head be shaved to make up for the slightly lower cr of a 2.7i?
-C'mon, guys help me a little.

[Jonathan M3]

You will also need an m20b25 intake manifold and TB.

[nando]

-How much can the head be shaved to make up for the slightly lower cr of a 2.7i?
-C'mon, guys help me a little.

stick to the minimum you can get away with. the more you shave your head the more your cam timing will be off.

[modifiede30]

I wouldn't recommend shaving the head further than allowed by specifications. In terms of what else you'll need, you can do this without changing the intake or TB. Keep in mind what you're trying to do with this because this will dictate what you should choose in terms of parts. The super eta intake is longer with narrower passages. This was used to create more low end torque. If you use the b25 intake, you'll loose some of the low end and gain some up top. The decision here is dependent on what you do with the car and how you drive. Personally, I chose the b25 since its a track car and I spend a great deal of time close to redline. However, coming out of tight turns makes the increase low end torque a valuable asset.

Injectors can be upped to 19# if you have any other plans for the engine. It definitely doesn't hurt anything and if you have an adjustable fpr, you can tone down some of the increased flow that might result.

Get a wideband unit so you can see what's going on with your fuel mixture. The narrowband monitors are crap and don't tell you anything unless you've got it floored and approaching redline. Keep in mind that the fuel mappings from the b25i and the associated chips are different than the super eta ecu and you'll want to know how to adjust things if you have this ability. Might want to consider a megasquirt, smt6 or split second for fuel changes.

Test your chips if you have more than one. I found that the stock chip worked much better than anything else until I found an Alpina knockoff. This is due to the fact that the timing in the b27i needs to be less advanced than what you'd find in most performance chips. Again, the ability to adjust fuel mappings is pretty key here if you can. Luckily, the Alpina knockoff has a great fuel curve from what I've monitored on the wideband during testing.

Nothing needs to be done to the head to accept dual springs since its the same casting - same with the b25i cam.

If I think of anything else, I'll let you know.