4AGTE 350rwhp/260rwkw build!

[trdee]

I made full boost at 4200rpm with a gtx3071r on my bigport gze. 0.64 rear housing.

The main benefit of the 20v head is vvt IMO. On a turbo motor it increases the powerband massively.

[oldeskewltoy]

1.6mm hks headgasket

Why? Are you running negative deck - piston above the blocks deck?

IDEAL squish/quench for a 4A is between .8mm to 1.0mm... 1.6mm is missing power


To the OP.... In a car like a Morris Minor (small, lightweight) you want to be careful about boost spikes.... It REALLY does matter what your final intended purposes is ( a question you should be VERY honest answering to yourself). If your desire is for a crazy dyno queen... there is a guy in Europe making over 700hp on a stock stroke 4AG (in a Datsun no less - http://youtu.be/lb8taD5wchg ) I don't believe I'd use it on the local roads

Again to the OP... Why use stock stuff? YES... the stock stuff is VERY strong... but it is also quite heavy. You can save OUNCES (not mere grams) on the internals by running quality aftermarket pistons and rods.... that will be not only lighter... but even stronger then the OEM stuff.

EXCEPTION - Most aftermarket cranks are about a kilo HEAVIER then the OEM crank - example TRD - This mass is to allow for enough counterweight to withstand the stresses of constant 10,000 rpm usage... and is why knifeblading a 4AG crank is BAD

Running aftermarket also allows you to "fix" a SERIOUS 4AG flaw - rod to stroke ratio - The Formula Atlantic engines now use rods slightly longer (about 5mm), the pin location in the piston is also moved the same amount higher in the piston. What this has achieved... the longer rod to stroke ratio has allowed the Atlantics to make their peak power 2000-4000 rpm lower then they did with the short rods.

Aftermarket piston also allow you to plan your compression ratio - (8.9 GZE pistons are only 8.9 to 1 under a 36cc - 16V head. Under a 20V head the compression drops - 20V head has more chamber volume then the 16V head, and so the compression drops.

Do your head work first... measure your combustion chambers, then do your block prep, then order your pistons and rods.

[trdee]

OST - your post is conveniently timed for me, as one of the last things I have to obtain for my 9AGTE build is a head gasket. Do you have more information about this ideal squish/quench number? Is this something that was passed to you from lyonings or something you found in your own research etc?

[samkaos]

Yer 0.64 rear is the key to get full boost in the 4000s.
VVT on turbo - just use adjustable pulleys and you can get the same overlap as a 20V if you want.
True stock ZE rods are mega heavy!!! Spool etc are much lighter.

[Big T]

Why? Are you running negative deck - piston above the blocks deck?

IDEAL squish/quench for a 4A is between .8mm to 1.0mm... 1.6mm is missing power

There had to be a fair bit machined off to square up the surface. Even with the 1.6mm hg, I ended up with 9.08:1 static comp with the 8.9 gze pistons.

[SHEPPO3930]

VVT on turbo - just use adjustable pulleys and you can get the same overlap as a 20V if you want.

Not really. The advantage of VVT is to use the initial cam timing to help spool up the turbo, when it comes on boost and above a certain rpm or tps value, you switch the VVT to the secondary position and this favors high rpm peak power. This has been proven many times. The only time you would get rid of VVT on a 20v turbo is when you go to big cams and/or drivability isn't a concern (drag motor).

[samkaos]

Fair enough, I am talking adjustable pulleys on a 16V to get the best compromise.

[oldeskewltoy]

OST - your post is conveniently timed for me, as one of the last things I have to obtain for my 9AGTE build is a head gasket. Do you have more information about this ideal squish/quench number? Is this something that was passed to you from lyonings or something you found in your own research etc?

squish/quench should be as tight as possible...the more action on the charge the better - http://www.ae86drivingclub.com.au/do...stonsquish.pdf

[30psi 4agte]

To make the power you want isn't as hard as you think... You can make 250rwkw with 550cc injectors and a std gze bottom end. The small port head is the onlY thing I'm not sure about. I always use big port heads on my combos.
However I have ported and flowed both heads and std type small port head will out flow a big port. So ican see no reason for you not to make the power you are after.
A half decent exhaust and manifold + the usual int cooler etc is all that is needed. About 20psi should get you close to what you are after.

I have done it numerous times.
My 2 bob worth

[trdee]

squish/quench should be as tight as possible...the more action on the charge the better - http://www.ae86drivingclub.com.au/do...stonsquish.pdf

thank you. bookmarked to read when i get home.

[NME308]

Just to introduce a bit of boosted theory!
http://www.modularfords.com/threads/...boost-pressure


Cheers,
Jason

[trdee]

squish/quench should be as tight as possible...the more action on the charge the better - http://www.ae86drivingclub.com.au/do...stonsquish.pdf

So I just had a read through it and whilst it would seem that having the tightest squish clearance is advantageous there doesn't seem to be anything in there specifically saying 0.8mm to 1mm is ideal for squish. from what I can see it just says that the 0.8mm clearance was better than the 2mm clearance. What info do you have that brought you to the conclusion that 0.8mm to 1mm is ideal for a 4A? TRD make an 0.5mm head gasket... would that not be even better if the ideal is simply to get the clearance as tight as possible??

That article doesn't seem to show huuuge differences between the 0.8 and 2mm squish. One would wonder if, on a turbo motor, a bigger squish clearance clearance would be more than compensated by the benefits of being able to run more boost thanks to the drop in compression gained by a thicker head gasket??? I would think so... For an n/a engine I can see there would be a clear benefit for running as tight a clearance as possible but on a boosted engine there would be other concerns to factor in, such as how deep the piston cavity needs to be to achieve your desired CR. That article said that combustion performance degrades with a deeper piston cavity, so yeah for a boosted motor I don't think it's quite so clear cut??

NME308; good link but preaching to the converted here I'm already running the lowest comp pistons I can get for the 9A before I hit the piston pins...

[Ken_T]

While we're discussing turbo's and quench pads, I've read that quench pads can be the cause of detonation in high boost engines. Anyone else heard similar?

[oldeskewltoy]

So I just had a read through it and whilst it would seem that having the tightest squish clearance is advantageous there doesn't seem to be anything in there specifically saying 0.8mm to 1mm is ideal for squish. from what I can see it just says that the 0.8mm clearance was better than the 2mm clearance. What info do you have that brought you to the conclusion that 0.8mm to 1mm is ideal for a 4A? TRD make an 0.5mm head gasket... would that not be even better if the ideal is simply to get the clearance as tight as possible??

That wasn't a 4AG engine... they were just discussing squish and its benefits/advantages....

A .5mm gasket was available, and as far as I can tell, on a new block, a .5mm gasket will provide about a .65mm -.7mm gap (there is about a .15 - .2 mm deck on a stock unmilled block) So as far as TRD, the absolute minimum would be about .65mm-.7mm. The rest of my information comes from conversations with a few of the Loynings engine guys, a tight squish is good. The area between .8mm and 1mm doesn't seem to improve things by much, but open up much beyond 1.2mm -1.4mm and it'll put the engine to "sleep"

Now as far as turbo (boosted) applications... I've been reminded numerous times that a turbo makes the air charge denser (high pressure), it doesn't necessarily increase the air flow (volume). Now once past the valve, even in turbo applications, the air charge expands and slows as it fills the cylinder. As the piston comes up squish will cause rapid motion in the air/fuel charge for a better burn...

Yes.. you can always turn up the boost... but if you can make similar power on a few #s less, then you can better design your compressor, and impeller to provide spool earlier, and so more mid-range power... sooner.


Ken_T - Are you speaking about 4AG boosted applications, or something a bit more general??? My boost knowledge is not as extensive as my n/a knowledge... so you may know something I'm unaware of......

[trdee]

Yeah I get the paper wasn't on a 4AG, was more just wondering where you had specifically gotten the number of 0.8 to 1mm from, which you have answered in your second line now so thank you

I think Ken might be talking about how the TRD bible mentions removing the "joggles" in the combustion chamber? IIRC someone previously mentioned that the sharp edges on the squish pads can be a source of hot spots in the CC which can lead to det. hearsay only though