4agze extractors on a 4ag head?

[PrettyCoolWagon]

Only true of the early bigport 4AGEs. The later bigports (and the bigport 4AGZEs I believe) are 7-rib and same size crank/pin as the smallport.

Sorry to OP - for being a bit off topic..
Yes Hiro,

You are right. I own a 1st gen AFM bigport 4AGZE from a JDM AE92 Levin & it's got 7 ribs but no ceramic pistons & no oil squirters.

Because of this I recently bought a smallport bottom end which I plan to put the big port head on.

What will this do to my compression ratios? - I'll be using the cometic steel racing head gasket.
Being a noob' I don't know about comp ratios & what the numbers mean exactly, so if you can tell me whether it means more top end or bottom end power, that might be helpful

[dangdang]

Wont affect the C/R, the deck height of the two blocks are the same.

In simple terms C/R is the how much the piston will "squish" the air fuel mixture at the top of the compression stroke.

For instance 9:1 comp ratio is the air fuel mixture compressed 9 times its original volume in the cylinder at the top of the compression stroke.

Higher C/R = more squish, which = more bang. It is limited however by a number of things, fuel octane being one.

Basically N/A cars run a higher C/R and forced induction ones a lower C/R as forced induction fills the cylinders past 100% volumetric efficiency anyway.

I'm sure Hiro can explain further.

[Gavatron]

Sounds like he's going from 8.0:1 early GZE pistons to the 8.9:1 GZE pistons, which will definitely change his compression ratio. It's not just about deck height.

[dangdang]

True, I was thinking he was only changing the block itself and retaining the same internals for some reason

[PrettyCoolWagon]

No.. Gavatron's right.

Originally I just bought the pistons & rods on ebay coz I wanted ceramics.
When I met the guy he offered me the block that the pistons came out of plus heaps of other stuff at a good price so I went for it, which meant I got oils squirters as well.
I figured as far as cylinder wear goes it'd also be a good idea to put the pistons back in the same block they came out of.

So... what's changing from 8.0:1 early GZE pistons to the 8.9:1 GZE pistons gonna mean in terms of power?

Has anyone got any weblinks so I can teach myself about compression ratios?

[TERRA Operative]

It means more power and you need to use 98 octane fuel.

[PrettyCoolWagon]

Sweet - I'm using high octane on the 4afe with extractors at the moment - she seems to like it.

[luke ae86]

no worries guys all this is helpfull to me so thanks for the info

[PrettyCoolWagon]

9:1 comp ratio is the air fuel mixture compressed 9 times its original volume in the cylinder at the top of the compression stroke.

Thanks Dang Dang - it's very basic when you put it like that..

..& using one of those triple steel cometic racing gaskets...

I'm guessing they increase the compression ratio a fraction more than a standard head gasket..

If that's the case, does anyone know how much more the compression ratio is increased?

OR

is it just a stronger gasket that will generally last longer?

[Casey-G]

Not in the slightest, it has many factors determining whether or not it will last, how it is prepped& installed being one of them.

[PrettyCoolWagon]

Not in the slightest, it has many factors determining whether or not it will last, how it is prepped& installed being one of them.

Sure sure.. Let's say all the prepp work's been done good n' proper - I feel confident a steel gasket would handle hard driving more than a common gasket. The mechanic I bought my bottom end off had an AE86 he did drift racing in up in Benalla, he said one of the first mistakes he made was blowing a head gasket because he just used a standard one.

That said I've heard the standard one is very good & to be fair the guy mentioned above was pushing well above 200kw

I've purchased one of the triple layer gasskets - I'm pretty sure it's .040" thick

Not sure how that thickness compares to a standard one or how much it increases compression.

[Casey-G]

Standard head gaskets are fine if used correctly. Saying something like the mistake was to use an OEM one translates to kinda a bad excuse for not torquing the head right/bad tune.

A metal head-gasket won't hold up all that much better than a OEM one from a decent knock/poor install.


40thou is a standard size HG for a 4age at 1mm, 4afe HG's are supposedly .8 which makes for a cheap compression up for the daily hack if you ever need to.

[PrettyCoolWagon]

Standard head gaskets are fine if used correctly. Saying something like the mistake was to use an OEM one translates to kinda a bad excuse for not torquing the head right/bad tune.

A metal head-gasket won't hold up all that much better than a OEM one from a decent knock/poor install.


40thou is a standard size HG for a 4age at 1mm, 4afe HG's are supposedly .8 which makes for a cheap compression up for the daily hack if you ever need to.

Yaeh.. I dunno Casey, I can't really speak for the guy as a mechanic, he's just who I bought the gear off.. & that's what he said happened on his first 4age ..he also blew a piston through a block on his 2nd 4age that had a billet crank in it which he claimed was producing 300kw... He was a pretty funny guy, he definitely sounded like he pushed everything to the limit..

Sold me the gear cause he was changing to rotary - couldn't get the power he wanted out of a 4age

Ok here's where I'm a greenhorn again
What is meant by "at 1mm" ?

&..

I don't quite follow what you're saying about the 4afe gasket...?
I'm guessing you're saying a 4afe headgasket can be used as a rough cheapy mod on a 4age to gain a little more compression. ??

Sorry if I sound a tad slow - I'm admittedly new to all this..

[Casey-G]

Sorry i meant 7afe, but yes apparently the headgasket is .8mm from the factory which is thinner than a 16v 4age HG from factory (1mm) but have the same oil/water/bore and bolt holes aka are a match, therfore is you own say a ae92 sx/gti with a 4age, you can bump the compression up on the cheap by buying a factory replacement 7afe HG instead of a "cometic/TRD ect" .8mm head gasket.

I'd like to meet the guy, cant believe everything you hear till its from the mouth (no offence) i know 300kW is easily doable on a stock bottom end with a 4age.. maybe he underated the toyo factory gear by mistake

seen a dyno sheet from a guy over in NZ with a 4agte hatch, pushing 32psi though stock gze internals with a blacktop head making in excess of 350kW at the front treads so its deffs doable.

[trdee]

stock 4AG headgaskets are actually 1.1mm if i remember right