Any experience fitting larger valves to the SOHC 4g63 head?

All technical questions and answers regarding starions, being modifications to maintenance.
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Starion VR4
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Post by Starion VR4 »

enthuzed wrote:The valves will still clear on the 64 head as the chambers are that much deeper...even after taking 1mm off it... They are a different shape too and bear in mind when comparing Starion 63 heads with L300 63 heads, the L300 has a smaller combustion chamber to the Staz one.

For more information, I built my engine using the L300 64 head with Galant VR4 pistons, and the crown was 12cc from memory instead of 14cc for standard Starion pistons (I had the high comp pistons originally in the Jap/NZ GSRIII one, also around 12cc).
If you built your engine like that... you will end up with 6.7:1 Compression Ratio.... :wtf:
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Post by ProZac »

Hmmmm, my measurements of my 4g63 head give a combustion chamber volume of around 57cc, which is a bit too big really. I measured a DASH head this evening, came out at about 42cc... Dash head would make things much easier in many respects already havging more intake valve area, and larger exhaust valves.... Just those rocker covers are so fricken ugly! Plus, I;d need different pistons again. Forged ones from the states are pretty cheap though...

Nonono, naughty thoughts, just slap it together and get it running already!

The graduations on my measuring device are worn off though, so I did it by weight using the mrs' super fancy baking scales... better clean them up good and not leave them in the garage ;-).
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Post by FST4RD »

Use the DASH head!
I would have loved to have got it going in my car, but lack of ecu and loom put me off.
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Post by ProZac »

Bah, factory ECU is shit anyway, if I do use it, it'll be MPI, probably still on the EVO ecu, with a little controller to turn on the extra valves when needed. Luckily the intake flange is really simple, so I can can CAD it up and get one laser cut pretty easily.

The manifold design is a bit puzzling however, as the two ports are completely separate, and I think the injector would have to be a little further up the runner than is ideal to make sure it's in an area of consistent airflow... But fuck it, I'll bash something together with a hammer and run with it. I can always blend the ports slightly, and continue that blending into the 10mm manifold flange...


Hmmmmmmm.
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Post by redzone »

Starion VR4 wrote:
enthuzed wrote:The valves will still clear on the 64 head as the chambers are that much deeper...even after taking 1mm off it... They are a different shape too and bear in mind when comparing Starion 63 heads with L300 63 heads, the L300 has a smaller combustion chamber to the Staz one.

For more information, I built my engine using the L300 64 head with Galant VR4 pistons, and the crown was 12cc from memory instead of 14cc for standard Starion pistons (I had the high comp pistons originally in the Jap/NZ GSRIII one, also around 12cc).
If you built your engine like that... you will end up with 6.7:1 Compression Ratio.... :wtf:
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enthuzed
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Post by enthuzed »

If that's the case, with the ARP head studs and graphite gasket, I can turn the turbo up to 30psi and she'll be sweet!! :twisted: :wink:

How did you arrive at that figure SVR4?
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Increase engine performance & prolong engine life...
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Starion VR4
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Post by Starion VR4 »

enthuzed wrote:If that's the case, with the ARP head studs and graphite gasket, I can turn the turbo up to 30psi and she'll be sweet!! :twisted: :wink:

How did you arrive at that figure SVR4?
Bore 85mm x 88mm stroke, 72cc 64 head + -12cc piston bowl, 1mm thick head gasket...

use this ratio calculator

http://www.csgnetwork.com/compcalc.html :D
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Post by enthuzed »

My calcs (using your 72cc) yielded 8.6:1 Derek.
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Post by Starion VR4 »

enthuzed wrote:My calcs (using your 72cc) yielded 8.6:1 Derek.
I think your using 12cc for piston dome... you have to use -12 as it's a dish piston... from the calculator..

"Enter Piston Dome Volume In CCs Negative For Dished Pistons (Use '-') "

:beer
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