20V Turbo Conversion

[I SL1DE]

Ok, after much debate as to what setup i'm going to run in my ae85 i think i have finally made the decision to run a silver top 20v with 4AGZE pistons and a turbo (probably S15 T28, maybe a TD04 or 05).

I have read heaps of information but just want to claify that the only differences between the 4AGZE bottom ends and the silver tops is the pistons, is this correct? My plan will be to buy a full 20v and buy a new set of 4AGZE pistons and rings. Do i need the late model 4AGZE pistons to clear the oil squirters in the 20v block? What part numbers are these and what price should i pay for a new set? If i run the 20v with a standard head gasket and the 4AGZE pistons what compression ratio will i have? From what i have read i gather that the pistons are what lower the c/r to 8.9:1, correct?

Matt Dunn (or someone else who knows), if you read this what internal setup are you running in your engine? Has your head been ported? Also are you using standard cams or aftermarket?

Also i would love anyone elses opinions on what they think of this setup or past experiences. Is there anything i have missed that is important??

Thanks,
Cam

[Mr Revhead]

you are spot on there

looking at $4-600 for rings and pistons depending on how soon you want them and wether you want stds or o/s
send me an email and ill hook you up

[matt dunn]

Ok,
Matt Dunn (or someone else who knows), if you read this what internal setup are you running in your engine? Has your head been ported? Also are you using standard cams or aftermarket?
Thanks,
Cam

My car has custom made pistons in it and i have measured the compression ratio to be about 7.9:1 i think it was.
I actually think that's a bit low and means it needs too mjuch boost to make decent power.
It also has aftermarket cams and has had quite a lot of head work.

I am actually in the process of building another engine at the moment with completely different spec's to try.

Matt

[10k 20v]

i'd be throwing in some arp rod bolts tho

plenty of people have had great results form the stock silvertop head/turbo combo.
good luck and let us know the results

[I SL1DE]

10k 20v: Your right it is very tempting to use the 20v engine as standard with a bigger head gasket to lower the comp ratio (a little bit). However there is a limit to how much reliable power you can make with the light pistons and rods that they have standard. Take a look at the AE86 in this months performance car mag, that's a lot of money spent on manifolds and turbos for only 138kw when you can run more boost with only a few small changes.....

For that reason i plan to swap to 4AGZE pistons and rods and put up with the 5 valve head vs 4 valve piston issue. Ideallly i would like to run with custom pistons but the little money i have is needed elsewhere on the project. ARP bolts will be a go either way along with a full freshen up and fully synthetic AMSOIL.

What other opinions are there about this setup?

Thanks,
Cam

[NZ_AE86]

10k 20v:

put up with the 5 valve head vs 4 valve piston issue. Cam

What do you mean by issue?? issue with what??!!

[evil_si]

with a full freshen up and fully synthetic AMSOIL.

do not run any form of synthetic oil straight after a rebuild / freshen up, personally i wouldnt use any synthetic product within 2000k

[I SL1DE]

NZ_AE86: Not really an issue i guess. I know the valve wont hit the piston but they just arent mae to be used with each other. I have no idea how much, if at all this will affect performance, maybe someone could clear this up?

evil_si: yes, fair enough. I mean after a standard run in process. Trying to run it in with synthetic would take forever .

[vvega]

there is no preformance issue with then
valve cutouts are purly a physical issue for interferrance with cam breakage

as for the componants one word .....tuning
with good tuning you sould have no isse with tis at in reliabily wise

v

[10k 20v]

i did mean a stock head with gze pistons slotted in the block
like no cams etc,
should of been a bit clearer i spose