Whats in common with a 20V 4AGE and a 'small port' 4AGZE ?

**nick.parker** · 25-01-2006, 08:03 PM

Hi,

I am considering the free flowing head of the 20V 4AGE as a future upgrade of my SC14 4AGZE setup. I have heard people of this forum say that 20V 4AGE has the same rods and crank as the small-port 4AGZE. Is this true?

The heavier crank and larger bearing surfaces sound at odds with an engine that has a higher rev limit etc..(more inertia and friction).

But, if this is true, it would mean simply inserting some low compression pistons (say 8.9:1 or 8.0:1) in a 20V would give you a nice base engine for a supercharger/turbocharger setup.

Regards, Nick.

**slide86** · 25-01-2006, 08:13 PM

yeah its been covered before. i think one of the main issues is the clearance between the valves and the piston when the valve is at maximum lift.

thats why 20v pistons are cut.....
ive seen the conversion on engines before and seen the heads on 7A-FE (now 7A-GE 20v)

http://forums.toymods.org.au/index.p...2071be8d06401a
http://forums.toymods.org.au/index.p...2071be8d06401a
here are two threads regarding the same questions

**nick.parker** · 25-01-2006, 10:19 PM

Hi,
Thanks for the links. There are lots of opinions about what is best. But no-one answers my question. Though I did read the head can be put on the GZE.

Has anyone out there compared the heads on say a turbo setup?

http://www.toymods.org.au/4A-GTE/

In the 4AGTE article. The guy says bigport head is best for turbo because the ports are bigger. But the valves are the same on both (16V) engines and are a smaller area than the ports...so surely this would be a more critical factor for 'restriction'.
The effective inlet valve area of the 20V is larger than the 16 valve and it has 0.5mm larger exhaust valves so why wouldn't that be better? He also says VVT is not necessary because you can get adjustable cam gears...that is missing the point isn't it!!! The cam gears cant change the timing while youre driving unless you don't do up the little bolts

Has anyone ever compared 16V smallport with 16V bigport vs 20V head on a turbo setup on a dyno?

Cheers, Nick.

**hamgatan** · 25-01-2006, 10:27 PM

*insert Bill Sherwood here*

www.billzilla.org ...

theres bound to be an answer there. i think bill goes into some detail about 4AFE and 7AFE heads.. so might see something about a GZE in there too if youre lucky...

**-GT-** · 25-01-2006, 10:44 PM

Originally Posted by slide86

i think one of the main issues is the clearance between the valves and the piston when the valve is at maximum lift.

thats why 20v pistons are cut.....

Yeah, but the 20V is non-interference, and lower comp pistons are going to give you more clearance, so no problems there.

**oldcorollas** · 26-01-2006, 12:10 AM

actually, both the GZE pistons are flycut for valves also (to the SAME depth), so if you use them with a 20V, chances are that it will become interference... thats ok.. just don't break the timing belt

are you sure the 20V head is more free flowing? the factry outputs ae a little fudged, and when both have ITB's, there is not much in it..

main reason would be ONLY for the VVT, but even then.. are you going to get better spoolup that is noticable? for an SC, it might be better,but lag is lag... check out the GT2510 thread of recent.

if you look in the GZE comparison thrad rom Witzl in the FAQ (i think), he says what is the same or not...

it semed (from memory) and each generation uses the same parts, regardless of type (NA, SC, 20V)

20V rev limit higher than GZE? duh, SC is not so efficient up high

But, if this is true, it would mean simply inserting some low compression pistons (say 8.9:1 or 8.0:1) into any engine would give you a nice base engine for a supercharger/turbocharger setup.

well.. logic says so...

if the 20V is your thing, and you are going for uber numbers (well.. say 20+psi) then by all means get some forged pistons for a 20V and go from there