small port or big port 4age for turbo setup?

[trdee]

Bigport 4AGZE's did not. any smallport block onwards (GZE or GE) did.

[luke ae86]

the gze block is being used as it is a 7 rib block the head will be removed from a 3 rib 4age hence not just rebuilding that engine entirely

[fixeruperer]

its all in the setup, when it comes to smallport vs bigport in the turboed 4a apps. ive seen both big and small port make impressive numbers. i know your not after big hp but i dont think there is any good argument on which is better for a boosted application.

theory states that the smaller ports will increase air velocity down low to improve torque and power.
just get your setup right and you will get everything you want.


if it were a question on a N/A motor, id say small port all the way.

[cri_ag]

Didn't the smallport 4AGE and 4AGZE both come with oil squirters?

yep.

the gze block is being used as it is a 7 rib block the head will be removed from a 3 rib 4age hence not just rebuilding that engine entirely

your ae93 smallport block should have 7 ribs? no need to buy a gze block.

[PrettyCoolWagon]

The 1st generation 4agze bigport didn't have oil squirters or ceramic piston heads.
I've got one from a JDM Levin AE92

There's also plenty of 3 rib 4age variants out there. These 2 websites should help clear up any questions:

http://www.twincam.org/topic/18712-i...ng-your-4a-ge/

http://www.ae92gts.com/ae92gts_engine_type.html

[BLK_20v]

You'll be relatively happy with using either head... I'd be more concerned about picking the correct turbo / ecu than what head to use.

Personally i'd recommend either td04 (WRX) or t25/28 (silvia) and a haltech sprint 500 ecu.

[Shifty]

We're talking about 160rwkw, you could make that from a K-motor so it doesn't matter which 4A he uses.

T28BB / GT28R & you're on a winner... you should make your desired power level on around 14psi.

Out of interest this is my old CA setup, 175rwkw at 6100rpm running ~15psi and 10.5:1 so on a 4A with a decent tune it should go similar power. You could probably even go smaller turbo-wise but depends what you want to spend. If you want a good turbo on a budget get a T28BB, otherwise one of the smaller-rated "GT25" turbos would be perfect but as they're a "buy new" proposition they're not particularly cheap whereas T28BBs are everywhere.

[dangdang]

It does matter if you don't want a slug when below 4500 grand and off boost, the bigports are HUGE, hence the t-vis plate to maintain some airspeed down low, and I mean who wants to keep the t-vis plate and figure its operation out with an aftermarket ecu? Not me for one.

Besides the T-vis plate would probably be a hindrance to all out flow.

Any one whose ever driven a bigport with the t-vis disconnected can attest, very doughy until the revs build.

Both heads are capable of making the same power, but the smallport will keep low down throttle response = driveability and honestly that counts a lot more than the final all out power figure.

[fixeruperer]

seat feel, is not that different. yes in N/A form you will feel the difference with a bigport without tvis. not really with a turbo
setup is everything.

[beerhead]

Both will be fine. I've seen a stock GZE bigport with a T3/4 come on song at 3500rpm. 300hp at 7000rpm.
Smallport is great for lower HP setups, or if you don't mind spending 3 days porting, but I'm a believer in bigport for high HP 4A builds. They do lack low end velocity, but there isn't many dyno queen 4AGTE's around that aren't laggy as hell, so bigports in this situation serve there purpose.

[Aust162]

Slightly off topic, but on the topic of 4A oil squirters:

can someone fill in the dots.
which motors have oil squirters fitted from factory??

Smallport 4AGE .... YES?
Smallport 4AGZE .... YES
Bigport 3 rib 4AGE ....NO
Bigport 7 rib 4AGE .... ?
Bigport 7 rib 4AGZE .... ?

Are oil squirters essential for building a low hp 4AGTE? >160kwatw?

[trdee]

Bigport 4AGZE's did not. any smallport block onwards (GZE or GE) did.

did you try looking on the previous page mate?

[oldeskewltoy]

Are oil squirters essential for building a low hp 4AGTE? >160kwatw?

nope.... as long as you have decent pistons, you should be fine

Most of the Formula Atlantic engines didn't use them

[PrettyCoolWagon]

^^^Serious?^^^

Still.. if you had the choice surely oil squirters would be best..?

[dangdang]

It does help but isn't 'absolutely' necessary, the rods have either slots or holes in the top section of their big end to throw oil into the bore any way.

Then again Formula Atlantics weren't forced induction and probably didn't experience blowby like a gze or turbo can.

People seem to quote them as helping with cooling of the underside of the piston, my thinking tells me its more to help keep oil coated on the bores with forced induction engines like the gze's that tend to have more blow-by which can stop the oil splashing up into the bores from the feed hole in the rod, dont want dry bores, the oils squirters inject it straight up there