High Compression 2.6L Astron.

[geezer101]

Even though S14 talk is a little off topic, I will share this though. This is a quick comparison of a S14 and 4G54 head gaskets. 4G54 being red, S14 being blue.

They look very close and would only take a bit of welding and machining to get the galleries to line up to the block. Too bad your images aren't overlapping correctly as the combustion chambers look spot on. The overhang for the exhaust gas channel (if that is what the bottom section of the gasket is...) will be deleted and the timing chain has plenty of space. The trickiest part will be the timing cover and figuring out the timing chain and sprockets. I think the other issue will be under bonnet clearance (but lets face it - if this is a viable mod you'd gladly sacrifice a bonnet to get this thing bolted up!). Gotta be a hell of a lot cheaper than a HKS twin cam head and waaaay easier to source.

[Old Colt]

The trickiest part will be the timing cover and figuring out the timing chain and sprockets.

Correct and I have not addressed this yet. The BMW head has idlers to guide the chain as needed to spread out to the cam sprockets, this makes the swap possible without getting to crazy.
The images posted are not scaled accurately, the bore spacing is spot on as are the fore-aft head bolt locations.
The width spacing of the BMW head needs the head bolt holes offset milled 3mm each , one G54 hole is a bit different as well.

[geezer101]

...The BMW head has idlers to guide the chain as needed to spread out to the cam sprockets, this makes the swap possible without getting to crazy. The width spacing of the BMW head needs the head bolt holes offset milled 3mm each , one G54 hole is a bit different as well.

Sorry Superscan, don't want to hijack your thread - can you get a build thread on your M3/Astron hybrid engine up for us Old Colt? (or even a link to a site where you've got some images etc) There would be plenty of interest even if its only at a non running development stage. There has been a lot of hype and trumpet blowing about the HKS twin cam head and it'll be unlikely that anyone will have the cash to replicate these things. Throw us a bone dude!

[cheaterparts]

Unfortunately I struck water with further straightening an intake port and never completed the head to running status.

With the help of Cheaterparts, the later heads seem to have a bit more "meat" to remove before hitting the water ports.

yes I band sawed a few heads up to see how they had been cast

...The BMW head has idlers to guide the chain as needed to spread out to the cam sprockets, this makes the swap possible without getting to crazy. The width spacing of the BMW head needs the head bolt holes offset milled 3mm each

Sorry Superscan, don't want to hijack your thread - can you get a build thread on your M3/Astron hybrid engine up for us Old Colt?

dont worry geezer about hijacking this thread if I know Scott the Ebay junky he allready scanning Ebay for a M3 head

and Charlie it would be good to see how your 2.6 TC weapon goes , long time no see by the way

[BAD-SIG]

Can't wait to hear more from both the M3 head and the 2.6 high comp build too! It's Astron porn!

[Superscan811]

Can't wait to hear more from both the M3 head and the 2.6 high comp build too! It's Astron porn!

The S14 twincam head does sound very interesting... When my big CNC mill is up and running I've thought about making one from scratch. Being able to use components off the S14 will make the job a lot easier.

My large carbide burr finally arrived today so I put it to work.
It made porting so much easier. The larger diameter and front radius means that I'm able to do port curves a lot smoother.

Haven't finished yet but here are a few pics.

Inlet BEFORE and AFTER.




Exhaust BEFORE and AFTER.





Just waiting on some money to come in so I can get the valves, seats and guides done.
Not expecting much change out of $600.



Cheers.

[bruggz351]

Hey Superscan, could you please humor a numpty as I have a question.
That seems to be a lot of material removed from the exhaust valve guide area. I'm assuming there is plenty of support for the guide in the head??
And does it not matter that the end of the guide boss/bore?? is no longer square??

Sorry if these are stupid questions, just curious...

cheers

[Superscan811]

Hey Superscan, could you please humor a numpty as I have a question..... Sorry if these are stupid questions, just curious...

Only way to learn is to ask..

That seems to be a lot of material removed from the exhaust valve guide area. I'm assuming there is plenty of support for the guide in the head??

Yes, there is plenty of support for the valve guide and part of the reason there is so much material is for heat dissipation.
The cast iron valve guides don't transmit the heat as well as bronze so they need to be "shielded " by the big chunk of aluminium.

And does it not matter that the end of the guide boss/bore?? is no longer square??

The guides go in from the top, which is square, but even that isn't totally necessary.
When a guide is being installed it is pressed in which changes the ID slightly so they need to be reamed back to the correct size.
Once in and reamed, the seat is cut true to the new guide. Of course you want it as close to the original angle as possible, but even if it's out over .5mm, the valve will still seat correctly.


Cheers.

[bruggz351]

Thanks Superscan.

cheers

[Speedcar96]

Hi. I was reading your build and very interested. Can you tell me the part numbers brands and details you used for the pistons for the high compression engine?

[Superscan811]

Hi. I was reading your build and very interested. Can you tell me the part numbers brands and details you used for the pistons for the high compression engine?

Sorry for the late reply but I've been away for a while.

The Wiseco K509M925 pistons are for a 1981 - 1984 Celica with the 22R engine. Hope this helps..


Had the valve guide replaced in the M8 head and had an extra 0.35mm shaved off, only to find that the engine is detonating a lot, even with 100 octane fuel.
Wound the timing right back to 25° but it would still detonate.
Bit the bullet and have gone to E85 as there are 2 petrol stations, 1 local and one on my way to work, that have it.

MUCH less detonation but I still need to tune it properly.

Initial feel is good but will see how it goes.



Cheers.