benau.

i was just reading through your post in the mods thread about the different head casts, from the way i read it this is what i understand.

an m9 cast head (with heart shaped chambers) with the flat top pistons would give a slight increase in compression over the round chambers with the flat pistons.

i have an m6 cast head in my car, but i have found an m9 cast head... in theory my pistons should be flat topped, so changing just the heads would give me more power... do you know if my cam is still going to go in it or do i need a cam to suit the m9 head?

where are the power gains going to be by increasing the compression.. is it just HP and/or torque? better accelleration, better top end? any ideas?

i've got a carby engine that i'm going to build up ready to swap into my car with my injection setup, so if this m9 cast head thing is going to be benificial then i'll do it while the engine is out... its still in the 1st gen at the moment... along with the 5speed manual... i'm gunna see how mine handles the extra power and if it holds up, then i might have a spare 5speed for sale.

cheers


Zach

ok....as i have said in another post from what i have found out, if you were to build an astron II for high compression using standard spec parts then the bits to use would be the M9 cast head from a TS engine and the pistons from a TR EFI engine
try to get the TS head complete with it's cam and roller rockers. Fitting TR cam and roller rockers should be ok too, I have been told the earlier Non roller rockers do not suit the TR/TS EFI valve stems because their longer

The original pistons for the TR efi engine should be different to all other earlier models including TR carby engines, All 1st gen and TR/TS carby engines have flat top pistons.

TR EFI engines also have flat top pistons but with raised crowns that protrude above the block deck and into the headgasket gap when at TDC.
TS pistons are similar to TR but they have valve shaped recesses in the top.

If your planning to fit this head to a carby engine then there should be a slight gain in both power right across the rev range and a slight improvement in economy, but by fitting it to a carby engine you are not going to get quite the same gain that could be expected from fitting it to a TR EFI bottom end.
If you wanted to get serious about compression then fit the head to a TR bottom end with piston that protrude, then measure the height above the block deck of all 4 pistons at TDC, measuring at 4 points on each piston.
Then get a head gasket with a compressed thickness that is just above the height of the tallest piston so it only just clears the head at TDC like a Toyota diesel should. From this point any further increase in compression can only be achieved by shaving the head.

For my next 4cyl magna project i intend to do what i have outlined above and find a supplier of variable thickness headgaskets for astrons, then it's time to experement with a 2.6L engine to find the max distance I can shave a M9 head fitted over a TR EFI bottom end and still expect it to run and drive well on 95ron pulp, i.e no pinging or excess heat.
This way I will have the build specs on paper for a Hi-comp engine using factory parts and can then put it on a dyno to see the result.

benau, thankyou for your reply. i have an engine from a 1st gen carby that i intend to do a bit of work to before i drop it into my car with my current efi setup.

i have been doing a fair bit of research into supercharging and will be setting my new engine up for a blown application.

the other area i have been putting a bit of thought into is intake temperature.

so far i have nearly completed the CAD drawings for an "inline charge cooler" ie. a device that cools the intake temperature that goes inline between the map sensor and the throttle body.

the device consists of a square block of aluminimum 50mm thick and 6 lenghs of 4mm copper piping (3 lenghs running horizantally and 3 vertically) through which i plan to pump liquid carbon dioxide or the more expensive, yet much colder option... liquid nitrogen ...either way i'm hoping to considerably cool the intake temp without using any kind of intercooler.

the other aim of this project is to utilise the same system to cool other elements under the bonnet ie. coolant etc.

a cooler engine is a happier one.

i'll post some pics of my progress as time goes on and i'm hoping to have the block all lathed up in the next week or so.

hope this might be of intrest to someone.


cheers

Z

I like your cooler idea, I had toyed with a similar idea,
I thought of fitting a cooler core to the engine inlet that was a small A/C evaperator and then plumbing the cooler to a standard A/C compressor and condensor.
The thing is would the gain be more than the power loss from driving the compressor???

If you intend to build the engine for force fed induction then you wouldn't want to lift the compression too far above standard ratios anyway, maybe just a M9 head on the standard 1st gen bottom end would be ok for a low psi setup. That sort of setup isn't something i have experemented with yet, i'm limited to turbos on standard turbo engines