Looking to get myself a set of Forged Wiseco pistons for my 1.6, 12psi Miata- looking for advice on which would be the best comp ratio?
I currently run 9;1 pistons (ex automatic engine) -which seems to be pretty det resistant, what are the thoughts on going for higher ratio,s.

 

you can get whatever you want. the common in stock ones are 8.8:1 which you probably wont notice any difference between them and your current 9:1 ones.

go higher and youll get a bit more low end grunt, but have to be more careful with timing/temps with increased boost.

 

I have the 8.5-8.8:1 wiseco's, not much can be said but I like them.

 

Any thoughts pro,s /cons on running 11.5 ;1 ,s ?- too much perhaps?

 

you can't run much advance. Its all about the ignition timing / iat / goal hp delta.

 

11.5:1 is pretty high to run with boost. You wouldnt be able to squeeze much in that engine without blowing it up. Especially with just 93 octane. Might be alright with 100 octane and up to 10psi.

 

You can run that kind of compression but you will likely have to run less boost and less timing. You will likey end up with similar HP numbers, Problem with the higher compression is tuning. It's not as easy to tune, mainly because you will want to run more boost and timeing eventhough you know you shouldn't. 11.5:1, and 5-6 psi and you'll want to see if you can get away with 8psi, or 10psi, or maybe a degree or two more of timeing. It's really not that best way to go.

 

sure- i was thinking that i could drop the boost to say 10psi to compensate for the higher comp- but wasnt sure on what effect it would have on ultimate figures.
should add i always use 99ron go-go juice over here in UK

 

i talked to an engineer at volvo once and brought up this question...
according to him, low comp & high boost>high comp & low boost...for longevity and power...

 

Why Wiseco? Why not order JE pistons?

 

If someone on this forum had an in with JE and maybe posted a thread showing what they offer and maybe a little discount i bet people would be buying JE pistons. Heck maybe he could even work out a deal with the forum admin to sponsor the forum so he had his own subforum. Then work out a production run of miata pistons and a possible group buy for all the people that recently bought forged rods here in the past 2 months.
If only...

 

Yeap, because you can remove the heat of compression from the boost, but not from the cylinders compression. Less heat is better.

 

This is the general mindset. If you know you are boosting the car you should keep the compression down.

 

back on topic why not look into some 10:1's?

 

I ran 10:1 on my N/A engine instead of 11:1 "just in case" I decide to go turbo later. I'd run a similar setup to y8s, a turbo just a hair on the big side, and low boost, probably no more than 12psi at the absolute max.

 

For sure- i,m thinking 10,s are as much as i will go- and of not limiting myself to only wiseco,s