99' stock head maximum hp
 

Hello I have a 99 ' 1.8L miata with gt3076r and made 395 whp at 1.8 bar of boost (more pressure did not made any difference)! I have stock sized valves and head except from retainers and springs ! Also stock intake manifold and throttle body! I want to ask you if I will have any gains from bigger throttle body and a begi intake manifold at the same pressure and what the maximum horsepower anyone have made with stock oem 99' head (stock cams without any porting)

You'll see gains with a bigger TB and better intake (there are threads on that very thing). You'll see significant gains from a port/polish, +1mm intake (and exh if you can afford it) and if you can afford them some springs, shim under bucket with high lift cams. It's all about that flow without sacrificing velocity. There are threads on porting the head but in essence, be careful. Too much will be way too much.

The SUB setup is required for high lift cams or you could spit out shims and grenade the head. That's essentially what I've gone with, except for the intake/tb. It should get rid of that knee in the torque at 6k and let me rev to 8k with plenty of torque. I hope at least..

now i know there are a lot of variables here, but

my built 99 head (thats for sale) made 65whp more on 3 psi less boost on a gt3071r

just sayin

Been waiting for a comment along these lines. This one was WAY nicer than I expected.

stock intake manifold = fail fail fail fail fail

Did someone say squaretop?

I know that a built head will make more power but mine is stock cams valves ! I want to make 30 whp with begi intake manifold and skunk 2 throttle body do you think it is possible or it will be a waste of money ?

i also had a custom fabricated manifold and 75mm throttle body.

square top manifold or a skunk2 ultra street manifold welded to a mazda flange.

But still at those boost levels with that turbo and a built head you should be me making a lot more power ( depending on fuel, on C16 you should be around 480)

With honda intake i must use honda throttle body and iac as well ? I have ms3 by reverant

Interesting reading, i'm just building my engine,and essentially im only changing my head to a fully ported (CNC Heads UK) 99 head with SUB lifters and supertech double valesprings,Supertech valves and Catcams high lift cams,but im still running my standard GTR turbo (VJ23) and inlet manifold.
I've no idea what it will make after its built,once its running its going on the Dyno to see what it can do. I was running 330BHP at the flywheel at 1.8 bar.
i'll post up the results here.

The stock 99 intake manifold is a piece of crap. I'd resolve that first personally before ripping into the head.

I would be surprised if anyone made more power on a stock 99 head than me - which is 458whp.

I got my head at a junkyard. The only work was to was machine it flat. Stock valves, guides, springs, seals, stock 7200rpm limit. Unknown mileage on the head :)

edit: 1.8 bar of boost sounds about right, I was at 2 bar (29 psi)

Soviet, what intake setup? This was with your EFR? Ops power seems low for the gt3076 compressor at 26psi. I had a built setup off the bat with nothing to compare to.

My intake manifold is a stock familia GTR one. I should of added my car is a 4wd 323 GTX. Or familia/protege over there.

With stock 99 manifold and stock throttle body I did 400whp on 93 gas using EFR6758 turbo at 26psi (https://www.miataturbo.net/dynos-tim...-6758-a-68914/)
With flat-top manifold and stock throttle body I did 458whp on E85 using EFR6758 turbo at 29psi (https://www.miataturbo.net/dynos-tim...et-fuel-75011/)

It looks like the square top added maybe 15whp and the rest was the E85? How much timing were you able to add with the E85?

a lot of timing, at least 10*

disclaimer: it was on different dynos, but they were both calibrated dynojets.

All of it.

Appropriate post, fae.

Who the hell let this happen?