Why not boost the ETA?

[ForcedFirebird]

Form what I understand the ETA has a 9:1 compression, correct?

I boosted a 9.1:1 GM V6 last winter and is running 12's in an auto FWD car. My Firebird has 11.5:1 and am twin charging it. I will see the same effective compression at 6psi as a stock 9.6:1 V6 with 10psi (which is common place in my community).

What people don't realize is that when you apply more air to an engine (boost), you are raising the effective compression (compression the engine sees while running).

So, if we have a 9:1SCR and add, let's say, 6psi over atmosphere, it translates to about 12.7:1 effective compression. You are still pounding the same ammount of air in that cylinder as a 8.5:1 motor at 7.5psi - although I am simplifying this, you get the point; cam, porting, chamber shape can all have effet on the outcome.

Let's discuss,

-John

[Need4Speed]

Because they will blow up?

[backtrail69]

Originally Posted by Need4Speed

Because they will blow up?

No... The reason its stupid to boost a eta engine is revs... HP is calculated (TQ x RPM)/5252 and if you arent spinning very many RPMs you aren't going to be making much power... also the head doesnt flow very well compared to an i...

[ForcedFirebird]

Originally Posted by backtrail69

No... The reason its stupid to boost a eta engine is revs... HP is calculated (TQ x RPM)/5252 and if you arent spinning very many RPMs you aren't going to be making much power... also the head doesnt flow very well compared to an i...

Then how do you explain the turbo diesels that won't turn as many RPM's as the 2.7 even?

What I want to know, is why is 9:1 compression too high?

Here's a vid for 'yas. This is a 9.1:1 at 15psi (the car I built for a customer last Dec)...

http://videos.streetfire.net/video/C...106_193741.htm

http://videos.streetfire.net/video/M...fun_166595.htm

A friend came down from central Florida and I made the kit from scratch for him in about 48hrs, the only thing that was made before hand was the headers up to the collectors (I made them on an engine stand). In that 48 hrs, found time to do the side exit exhaust, and make the small items on my CNC machines, like flanges etc.

[ban1]

Just boost it and if you dont like it throw an i head on it ,but you could just go ahead and put on the i head.(FLOWS BETTER)

[napabavarian]

Do it to it it'll be a torque monster if it is done right.

[ForcedFirebird]

Originally Posted by ban1

Just boost it and if you dont like it throw an i head on it ,but you could just go ahead and put on the i head.(FLOWS BETTER)

Yes, I know about the i heads

I'm doing the same thing on my v6 motor. Using a '94 block and '04 heads in the Bird. The old iron heads flow ~127cfm intake and the aluminum '04 heads are ~225cfm.

My question still remains:

Why is the compression on an eta too much?

[ForcedFirebird]

Originally Posted by napabavarian

Do it to it it'll be a torque monster if it is done right.

Oh, I have a few plans for the eta

I'm swapping in a GM ECM (same ECM that controls a Syclone/Typhoon ), then an i head swap, then undecided if I want to see big N/A numbers, or boost it.

[backtrail69]

Originally Posted by ForcedFirebird

Yes, I know about the i heads

I'm doing the same thing on my v6 motor. Using a '94 block and '04 heads in the Bird. The old iron heads flow ~127cfm intake and the aluminum '04 heads are ~225cfm.

My question still remains:

Why is the compression on an eta too much?

The compression is not the problem its the shit head on it..

Here is my 2.8 (2.7 crank 1mm overbore and i head (stock with 273 cam)) at only 10 psi... I suggest you invest in i head swap

[ForcedFirebird]

Originally Posted by backtrail69

The compression is not the problem its the shit head on it..

Yes, I understand the flow difference between the i and e heads.

BUT the same goes for my other car (as explained above), yet the iron heads with boost will still do quite well (~12-13sec 1/4's).

When you have a lesser flowing head and you apply boost, you have lesser issues with port volume, velocity, and definatly making power, than you would talking N/A.

Does anybody here (or can link me to threads with) flow data on the various stock heads? Perhaps someone maybe even went as far as testing with/without manifolds as well?

EDIT: I posted before you pic insert of the dyno graph

Anybody have numbers on the e head and boost?

[ethree]

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

[ForcedFirebird]

Originally Posted by ethree

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

Only if you over-rev

[ethree]

Originally Posted by ForcedFirebird

Only if you over-rev

Or have a spike in boost

[Jordan325iC]

I have never heard anybody argue against the ETA because the CR is too high. People argue against turboing an eta because of the shitty head (which you already knew). Only uninformed people would argue that 9:1 CR is too high for boosting.

[ForcedFirebird]

Originally Posted by Jordan325iC

I have never heard anybody argue against the ETA because the CR is too high. People argue against turboing an eta because of the shitty head (which you already knew). Only uninformed people would argue that 9:1 CR is too high for boosting.

Ah, OK.

I went through and read a bunch of boost related threads, and it seemed the compression was mentioned often.