Mk1 4a-gte project

[PW@Woodsport]

Ok so i've seen a lot of failed attempts at this over the years, and very few successful ones, but mostly short lived in my experience. Anyway i also own a Mica blue Supercharger, currently running with Fensport big pulley kit, ABV mod, LSD manual gearbox.

It goes pretty well as you would expect, not in the same league as the Mk1 3s-gte conversions or V6 versions torque wise but a quick little car all the same, however i fancy having a proper go at a reliable 4a-gte, the Woodsport way, it's an itch i've been dieing to scratch.

I have a spare 4a-gze engine so no need to touch the current SC install, meaning if things don't go entirely to plan i can fall back onto the SC motor.

The plan is to run a T25, on a Woodsport exhaust manifold (i'll Tig this up with 3mm wall stainless weld els, a T25 flange and a 4a-ge header flange), but will be my own design. It should start producing boost at 2000rpm with the emphasis on midrange power.

Management will be stock gze injectors and ECU (for now), provide it with decent cooling (possibly chargecooled, i have a rather nice Lotus setup here), with a target goal of somewhere between 200-250bhp, nothing amazing but primarily the goal will be keeping it bombproof.

I will also mate this to one of our 6 speed gearbox conversions instead of the SC box, the emphasis on this project will be weight saving with lots of power.

The engine itself will get a full rebuild, MLS gasket, ARP bolts and will run a 16v intake plenum (also have an AE86 one if i fancy changing the pipe routing to the drivers side)

Anyway, that's the project, most of you who know my build threads will know you're in for a pretty good write up, so hopefully it will help others, it won't be as groundbreaking or mad as the other stuff we've done, but an excercise in doing it right.

That's the plan anyway!

[autobody]

interesting project. Looking forward to the updates

[kaiowas]

Excellent, will be watching closely and hopefully it'll give me the kick up the ar$e I need to finish mine.

[aw11rally]

Tune a 4a-ge, surely you're completely mental and should be locked up.

Only joking.

I eagerly await your updates Paul.

Sod the standard ECU, can we have functioning anti-lag and launch control please?

[Lauren]

To be fair, I reckon 240ish bhp should be totally reliable.

A later spec GZE is preferable if that is what you have as it has the MAP sensor of course instead of the AFM as the AW11 one does. Also the later engines have a slightly better spec.

I was going to do this years ago and even had a Carl Crawford manifold, but in the end given I used the car for track work, I reckoned the balance was good with the power it had and then well the car fell apart rusting to pieces.

[PW@Woodsport]

I think one of the previous pitfalls was people trying to use the NA 4a-ge as a platform, not saying that can't be done, just that it leaves itself vunerable to the quality of engine builder when fitting low comp pistons/rebore etc etc

I think the best way is to use the late spec gze as Lauren says, sadly of the three 4a-gze motors i have at the garage, they are all early ones, still i've no complaints about using the AFM for now and can lower the CR a little further if need be with a thicker HG.

I do have another gze engine tucked away that appears to have come from a Corolla or Levin, but it is a bare engine and i don't know wether it is a late or early spec one.

Is anyone aware of a late/early GZE easy identifier on the outside of the engine? The only clue i have is a coilpack type distributor plugged into it.

[Lauren]

The DLI is certainly an indicator of an AE92 engine and onwards. Also the oil drain at the rear of the block is an easy way to tell what (roughly) bottom end you have.

[PW@Woodsport]

Just checked my spare engine and it is in fact a late spec with the oil drain, cheers Lauren, do you happen to know offhand what CR that should be compared to the early spec?

[Mk1Chris]

So you are building my car then?

I used a later spec block from a corolla with the full mr2 afm, wiring loom and injectors.

I can tell you it will all work fine with that set-up Paul, just make sure when you rebuild the engine you check the piston rings

You will need the inlet manifold from an NA corolla with the late spec 4AGE engine and then you can use the throttle body from a mk2 mr2 with a couple of the pins swapped over for a direct replacement for the supercharger throttle body. That means you can retain the idle control

[PW@Woodsport]

Many thanks for that Chris, i will follow your advice on that.

I like the sound of the Mk2 throttle body too

[Lauren]

Just checked my spare engine and it is in fact a late spec with the oil drain, cheers Lauren, do you happen to know offhand what CR that should be compared to the early spec?

http://club4ag.com/faq_and_tech_pages/4A-GZE_specs.htm

But in summary early is 8.0 and later spec is 8.9.

Later engines have oils squirters under the pistons too.

[PW@Woodsport]

Thanks Lauren

Yesterday i removed all of the SC equipment from the engine, the SC is the later type with the smaller pulley and the head is the smallport type.

I am thinking about possibly using the 20v head on this late GZE block now.

[Lauren]

I'm not sure the 20v head will gain you much if anything at all. The smallport engine is the preffered choice really for forced induction.

[PW@Woodsport]

Just following some advice given to me by an Australian guy that has done a few gte builds, he reckons the 20v head is much better for FI.

[Lauren]

You may need the 20v pistons and rods to go with it.

[PW@Woodsport]

Yes i did wonder about that, would that be for the valve cut outs? Then if i use 20v pistons they won't be low comp ones..... hmmm , more reasearch needed.

[kaiowas]

That's probably not a road you want to go down. My understanding is that if you use the 20v pistons you'll need the rods to go with them which aren't as strong as the 16v ones. Giving up the strength of the 16v parts would seem to go against the original plan of keeping things reliable.

[aw11rally]

How did toyota reduce the CR on the GZE motor?

I'm sure the head is identical so I'm guessing shorter pistons. In which case the valve cut outs may not be an issue as the piston stops short at TDC.

[kaiowas]

How did toyota reduce the CR on the GZE motor?

I'm sure the head is identical so I'm guessing shorter pistons. In which case the valve cut outs may not be an issue as the piston stops short at TDC.

It's the pistons that are different.

The MR2 4A-GZE bottom end is identical to a 7-rib 4A-GE with the exception of the pistons (that are £50 something a piece from Toyota from memory)

As a consequence you can use an n/a engine as a base for a project like this if you swap the pistons over. Can be easier than sourcing a 4A-GZE although it's only really feasible if you're planning on using aftermarket management.

[Lauren]

I suppose you could work out whether using the low compression AW11 GZE pistons or even the slightly higher compression (and better) AE92/AE101 GZE pistons will work with the 20v head?

It's a non interference engine after all.