Help me! What motor? Blacktop/7A/Silvertop arrgh!

[mullett]

So I decided that my tired old GZE was a bit long in the tooth, what with all the oil leaks and the odd rattle it makes every now and then, and basically that I wanted more top end, less noise at cruise and a smoother motor. So that rules out the Supercharger. I've got a very good condition 7A, 2 bigport heads, and my old GZE block complete. Also I can pick up a blacktop or silvertop fairly cheap. I've pretty much decided to go turbo, but the rest is causing me headaches. Do I:

1: Put the blacktop head on the 7A, with the 8:1 GZE pistons and aftermarket rods (giving me about 8.9:1), and use a turbo.

2: Use the blacktop motor, with the GZE pistons and rods, with a turbo.

3: Use the 7A, with the standard internals and the blacktop head, and leave it stock.

4: Use a silvertop motor, with new 8.9:1 pistons and a turbo.

And another question:

The blacktop inlet manifold: Metal or plastic? Can I put boost through it?

Cheers guys!

RM.

[deviant]

Not keen on a Gen 3 3SGTE?

Go crazy and steal my ideas....Honduh Vtec K20A. 200BHP, 150torques, 6speed box and LSD. Or the other idea was a Mitsubishi 4G63 (Evo engine)...massive torque, power and reliability

[EldarO]

MattAE86 was using a silvertop turbo, afaik he killed a couple, so PM him and see what he thinks.

Elmo.

[jezza323]

i would go with a 7a block, bigport head and turbo

well actually id go the 7a block, bigport head, black top throttles, big cams, n/a power

but yeah, no need for a fancy 20v head if you are gonna run a turbo IMO, and you have 2 bigport heads sitting there....

[Nim]

I think you'd be better off grabbing a turbo engine if you want turbo power. Cheaper in the end.

But then, if you wanna do something different. *shrug*

[nick.parker]

How much power?

1. Option sava-da-money
-Sell the 7A
-Buy TVIS (bigport) manifold and throttle put it GZE (dont use tvis plate and weld up valley to delete air leaks)
-Turbo with 15ish psi (TD04L for cheap)

2. Cost-a-mora
-Buy a blacktop
-use 4AGZE pistons and rods
-Add turbo
-Sell 7A

3. 'Gold rush' 7A setup
-custom rods
-custom pistons ( could use 8.0:1 GZE for 8.8:1 7AG)
-blacktop head
-Turbo it

There are heaps of permutations! Yet another option, I didn't mention :- for turbo I think I'd lean towards a small port oil squirter 8.9:1 4AGZE with n/a smallport inlet manifold/throttle (for an all purpose street car).

Nick.

[mullett]

Yeah, that's exactly it. I've got the bigport NA manifold etc already sitting there too. I like the blacktop idea for the: Quads, VVT and just because it looks really really neat But yeah, the budget option is definitly to rebuild my current motor and sling a turbo on the side. Argh! Decisions. I also like the oil squirters and other things on the newer motors. Cutting down the lag is a big thing for me, so the 8.9 comp ratio is a given, and the VVT would be a good thing too... Costs:

Build 1:
Blacktop: 1k
Custom 7A rods: $800
Misc gaskets etc: $300
Turbo setup

Build 2:
Blacktop: 1k
GZE 8.9 pistons: $500
Use GZE rods
Turbo setup

Build 3:
Not really worth it...

Build 4:
Silvertop: $800
8.9 pistons: $500
Custom plenum: $400
use existing rods
turbo setup

4A+ turbo
Rebuild kit: $400
8.9 pistons: $500
Turbo setup

Hmmm. Too hard! I'm going on holidays!

RM.

[30psi 4agte]

Smoothness = 20v but the 16v can also make good grunt and still be smooth.

You can make 250rwkw on std big port head and cams

[fixeruperer]

yeh ive only heard bad things about trying to get much out of 7a rod's so if you were gonna go 7a get forged rods (this is more money), i say build a tuff 16v if you buy a gze all your parts are there just buy a turbo other parts and POW have 250hp at wheels starting point. thats a tasty starting point.

[mullett]

Yep, it'd have to be custom rods for the 7A. 250RWHP is certainly a possibility (and not that hard from what I've heard), but I NEED it to still be torqey and have good response across the rev range...I'm starting to swing to keeping the ole bigport and just getting some 8.9 pistons. Does anyone have any real world experience, or even theoretical, about the difference in response and lag between 8:1 and 8.9:1 comp in the 4A?

RM.

[nick.parker]

I don't have experience...but I have seen more and more magazine articles appearing on the subject of high(er) compression turbo charging. Got a mag a home talking about a Perth place turbo'ing SR20DE's (10:1 or something) and running 14psi to gain WADS of torque and good power with great drivability. RB25 Skyline are 9.0:1, 3SGTE are 8.8:1 = basically same comp as a high comp GZE . Cams and turbo become a more restricted choice though. Usually exhaust sides are freer flowing to help decrease detonation risk (by enabling HOT exhaust to be more effectively removed from the cylinder). Maybe someone with some real knowledge can explain .

[Mooro]

Yeh turboing SR20de's is very common now and they are known to be torque monsters. Personally if I was going down this path I would be tempted to get a standard silvertop and running something like an RB25 ball bearing turbo or a ball bearing T28 on the stock bottom end in a low boost setup.

With good intercooling (probably W2A in your case) I think it should be possible to make decent power/torque and limit the lag you will gettign have any decent sized turbo on a small engine.

Being a newer engine if you get a good one it should be in decent condition and with careful tuning and good cooling it should last. If you do happen to break a piston then you can choose to put GZE ones in if you want run higher boost

I reckon that would be one of the cheapest and most driveable options.

I guess it depends on your goals though, obviously you won't be able to run heaps of bosst on the above setup but there is the option of doing that at a later date.

[kassma]

Hey All....

The most benefit you will get from running a low boost setup is that intercooling is not really required. the majority of the heat is derived from the compression of the air, and hence, if you only run about 4-6 PSI boost, which is within the limits of a good T25/T28 turbo, you won't really need an intercooler.

None-the-less... for summer applications, I would probably recommend to run a W2A intercooler setup, which cost next to nothing nowadays or A2A which is even cheaper.

I believe, from reading some past posts, that the stock 20v ST intake plennum is good for about 4PSI boost.

The main attribute you will need to look for in the turbo is the amoutn of air it flows...

I believe that is what the 20v BT Blitz turbo kit does...

Just my 0.02 cents worth...

MIKE.

[mullett]

All great info guys, cheers! The only unknown is still how strong the blacktop inlet is. I'm going away for 2 weeks, doubt I'll have net, but keep the suggestions and info coming!

Cheers, RM.