Why not boost the ETA?

[gothguy70]

Considering doing the i head sawp and eventually a turbo.My mitsubishi starion in turbo and want my 325 to be also.It's an E si I know all to well about what starts happening near 5k.I found a 325i last week and asked the guy how much for the head.$650 cash for whole motor.He said it was a 2.5.Is this the i head to use or is there a 2.7 i out there?Kinda a stupid question but just wanna be sure I'm getting the rite stuff.
What do I need to collect part wise to make this swap work?injectors,afm,wiring harness or whatever else.I would just buy the whole car but i'm running outta space for cars,parts and dogs.

[ForcedFirebird]

I wasn't really speaking of you specifically, there were some other comments in this thread that lead me to post that.

anyway, you are right that a static 9:1 CR won't neccesarily hurt you under boost. The big thing is going to be exhaust restrictions and the cam profile, that will control where your knock threshold falls for a given compression ratio. basically the higher the static CR, the more agressive your cam needs to be and the less restrictive your exhaust should be. Which essentially means a high CR eta block with the stock eta head, cam and exhaust is going to have a much lower knock threshold than an engine with the same CR and a better flowing head.

Oh I know the old trick of using an agressive cam for lowering cranking pressure, the Firebird has a 291/306 bumpstick ;)

[David Alejandro]

Don't weak single valve springs like those found in the eta head like to allow valves to float and fuck shit up?

you can always put an i cam and springs in the eta head, if you have that stuff sitting around. I have a similar set-up, with some port work, chip, etc, and it works great. The valve size is still slightly smaller on the eta, but boost can overcome quite a bit of that deficiency! Double springs really are needed if you are gonna drive the thing ;)

(i actually picked my car up for $400.00, accident victim, just got a backup motor that I'm building ($140!!! ), with a getrag, ecu, afm, etc etc etc.. I'm rebuilding it now for a swap... gonna b a 2.8i, motronic 1.3 chipped, etc.. I got an i head, manifold, bored TB, m30 afm..

[nando]

I wasn't really speaking of you specifically, there were some other comments in this thread that lead me to post that.

anyway, you are right that a static 9:1 CR won't neccesarily hurt you under boost. The big thing is going to be exhaust restrictions and the cam profile, that will control where your knock threshold falls for a given compression ratio. basically the higher the static CR, the more agressive your cam needs to be and the less restrictive your exhaust should be. Which essentially means a high CR eta block with the stock eta head, cam and exhaust is going to have a much lower knock threshold than an engine with the same CR and a better flowing head.

[ForcedFirebird]

everyone always thinks having a butt-plug for a head is going to help a turbo spool up faster. quite the opposite is true, a stuffed up head is going to lead to higher EGTs, lower knock threshold and lower overall power, in addition to spooling slower. And given the same pressure, the I head is going to flow a lot more than the e head regardless.

there is a thread that shows the flow rates of the different M20 heads on e30tech.. I don't have a link but somebody did some pretty extensive testing. the 885 is up there with the porsche 2v heads and the LS1, the eta head just can't compete, especially if you do some port work and throw in a nice cam.

On the contrary, I completely understand the concepts of boost, here is an example of the head I went from to in my Firebird.

Stock intake flow is about 127cfm at max lift (.400")...



To about 225cfm at max lift (215cfm at the same .400")...




And both units ported (147cfm and 250cfm respectively)...







Again, this thread isn't going in the direction I expected. I was hoping for a discussion on static compression and boost...

[nando]

everyone always thinks having a butt-plug for a head is going to help a turbo spool up faster. quite the opposite is true, a stuffed up head is going to lead to higher EGTs, lower knock threshold and lower overall power, in addition to spooling slower. And given the same pressure, the I head is going to flow a lot more than the e head regardless.

there is a thread that shows the flow rates of the different M20 heads on e30tech.. I don't have a link but somebody did some pretty extensive testing. the 885 is up there with the porsche 2v heads and the LS1, the eta head just can't compete, especially if you do some port work and throw in a nice cam.

[norcalE30]

I had a chipped ETA and the rev limit was at 5500. At about 5-5.2k the valves started to float, you could hear it and feel it. If you really want, you can put in the i double valve springs and cam. But you need to take the head off to do it, and while it's off you might as well just put the i head on.

would there be any power increase with this swap on an NA car?

[ForcedFirebird]

I run 7psi on my 10.5:1 m42.

Nice.

I had a chipped ETA and the rev limit was at 5500. At about 5-5.2k the valves started to float, you could hear it and feel it. If you really want, you can put in the i double valve springs and cam. But you need to take the head off to do it, and while it's off you might as well just put the i head on.

Why can't the springs be changed with the heads on? I've done it multiple times on various cars? Take the spark plug out, feed some 1/4" rope in the hole until no more can fit, then rotate the engine until the rope holds the valves from falling into the cylinders. I've also used compressed air and a compression tester hose to fill the cyl with air, it will hold them up as well but more times than not, it's a pain to get the hose in there or it gets in the way while working.

I will probably end up doing the head top end swap, but started this thread because I was reading old threads and saw how many times it's mentioned that there's too much compression and the i head is a MUST.

Here's a good example of high CR and boost on a BMW...

http://www.da-motorsport.com/projeler/mz3/mz3_en.htm

[SamE30e]

Only if you over-rev ;)

I had a chipped ETA and the rev limit was at 5500. At about 5-5.2k the valves started to float, you could hear it and feel it. If you really want, you can put in the i double valve springs and cam. But you need to take the head off to do it, and while it's off you might as well just put the i head on.

[Manya]

Any progress on your E30?

I have a line on a blown eta motor (timing belt victim) and will soon have a good m20b25 head out of an e34. Depending on the shape of the bottom end of the eta, I may have the makings of a decent project.

MS + Supercharger should make for a fun car, even in an e34.

I bought my e34 for $400 due to it being a timming belt victim, the only thing the bottem end suffered was a couple of tinny marks in the pistons, that was with 10 bent valves....

I'm going the MS + turbo setup for mine.

[Danny]

I run 7psi on my 10.5:1 m42.

[autophile]

Any progress on your E30?

I have a line on a blown eta motor (timing belt victim) and will soon have a good m20b25 head out of an e34. Depending on the shape of the bottom end of the eta, I may have the makings of a decent project.

MS + Supercharger should make for a fun car, even in an e34.

[ForcedFirebird]

Have you looked at www.car-part.com for an engine? $1500 sounds like a high price for a used engine unless it is installed.

HAHA, i might as well have stock in that site

I buy at least 6 or 7 engines a year for my shop ;)

It's just the Triton motor, they are a 100,000 mile tune up, so when they have 60-70k on them, they aren't cheap. I got 200,000 miles out of it constantly being overloaded and I'm not easy on it, but it overheated when my dad was driving it (I was in the car behind being towed) and he didn't notice until it was too late. I could change the head gaskets, but it's a pain with the OHC's, and the bottom still has 200k. Not to mention there ws a few cups of coolant in the oil, I'm not going to do all that work and have it go again. Crate motors are about $5k, and I just can't replace the truck as cheap as I can swap the motor, the rest of it is in good shape.

[napabavarian]

Have you looked at www.car-part.com for an engine? $1500 sounds like a high price for a used engine unless it is installed.

[ForcedFirebird]

Right now the plans for the car are open. I'm gathering parts to do the GM OBD1 ECM swap to get a hold of the engine management (I started a thread here about it). After which, I really need to do the timing belt and figured I may swap the head while I'm at it. Then once the Firebird is done, maybe some boost, dunno yet.

Firt item on my list is to get my F150 back on the road. Used motor is going to set me back $1500 or so, and need at least two vehicles running (have four kids, soccer etc). Once that's finished, the 30 can go under the knife.

The 30 needs some TLC now. It still only has just over 80k miles, but the wife banged up the front fender, then shortly after I bought a new one (ebay for $100 aftermarket :D), a drunk driver side swiped it and fubared the other side. Thing was mint when I got it :(

Firebird is a 1990, you can see my vehicles here...

http://www.fquick.com/Forced_Firebird

Need to update the pics soon haha....