High Compression CA18DET

Since i got my std SX back and using it as a daily. I have been thinking how can i make it better. Most new cars run high comp and low boost. Now if you could do this on a CA18DET which is 8.5:1 and get it to something like 9.3:1 you would get better fuel con and more power low down without the turbo.

Only two way i can see of doing this is

1. CA18DE pistons
The CA18DE has no oil squirters but could be "made" to work and 9.5:1 might be a bit high

2. Skim head and block.
Wont get get that much but will be more

So what you think?

CA18DET has flat top pistons so skimming the block and pistons wont help. Skimming the head would be easiest.

I find this interesting!

Wouldn't you run a risk of too much is too far kind of situation in an engine that isn't designed for high comp?

djtreble wrote:

I find this interesting!

Wouldn't you run a risk of too much is too far kind of situation in an engine that isn't designed for high comp?

remember people run 1.2bar boost on a CA18DET with bigger turbo's on std HG now i am not saying up the boost as well maybe even drop it from 0.7 to 0.5

The CA is a strong engine. i remember running 1.2bar maxing the injectors everyday then dropped to 1 bar still maxing the injectors for well over 1 year

Gary57 wrote:

CA18DET has flat top pistons so skimming the block and pistons wont help. Skimming the head would be easiest.

How much more compression would you get?

It's strong as long a sthe big ends last! haha

Don't think you'de get as much as you are after by skimming the head. Are are limited by factory design

You can skim loads off the head, only problem will be you will need to pocket the pistons so they dont hit the valves. Best thing would to buy 9.5:1 CP pistons, DOT ( . ) did on this very forum...

That was my concern was the valves limiting the amount

I dyno tuned alot of CA18s within the space of a month or so, most with pretty much the same mods. They all made within 10hp of each bar this one thats head had been skimmed to max, and it made 20hp more than the rest. Only difference between it and the rest was the head skimming.

What type of mods did they have?

Also it isn't just mods that will affect the bhp if you are only talking about a difference of 10bhp. Engine's maintenance can make as much of a difference. then there's the obvious exhaust and turbo differences (in type and condition)

Unless these were all freshly built engine by the same shop, it's hard to call that the difference was the head skimming when you are talking about a difference of 10 bhp on a turbo engine.

All had exhaust, cooler, filter, the basics. This one made 20hp more than the highest of the others.

Sorry I missed that...thought you meant the others made 10bhp higher and this ne made 20bhp higher so a 10 different. 20 is a bit more.

Fit CA18DE pistons, run 0.5 bar boost. 9.5:1 comp isnt too high for low boost. Std RB25DET is 9:1, and they can run over 1 bar boost. At least by fitting other pistons, u can go back to std again, but by skimming a lot off the head, there is no going back.

i have high compression piston on my SR~! 9.01^^ but i have thick HG to balance it

Does the DE have domed pistons??

Yes, with pockets for the valves.

Since the DE doesn't have oil squirters they don't have the oil hole though.