Turbo for BRZ to run on 95RON and expected gains

[Teppka]

I have automatic transmission 2020 BRZ. Was planing for Supercharger but in the European region I am it will cost over USD 8500 landed if not more (taxes, shipping etc). Hence I’m thinking about turbocharging. I discussed this with my tuner the custom setup. Probably will go with smaller turbo to have it start spinning sometimes at 1500 rpm as my understanding bigger turbo will deliver more in the upper rpm range but I want to eliminate torque dip and turbo lag. No plans to race/track the car, normal road use with casual pull ups. My goal is to get rid of torque dip and add ideally 100hp. Also it will be a good 1 stage setup ready for increased boost if I’ll decide to go with forged internals. I already installed custom catback exhaust with increased diameter. Will probably have to delete cat converter for higher flow on turbo. As per my research my understanding is on stock internals I should go with 7psi maximum. Gas we have is 95RON (East Europe). My question is what maximum boost should I go with to be safer with stock internals and what power gain I should expect on 95RON gas. I should also probably update injectors to allow more fuel.

[tomm.brz]

were your thinking of some turbo in particular? a greddy t518z for example gives around 0.45 bar with stock wastegate spring and you can reach around 280hp to the crank with 95 Ron

[Teppka]

Originally Posted by tomm.brz

were your thinking of some turbo in particular? a greddy t518z for example gives around 0.45 bar with stock wastegate spring and you can reach around 280hp to the crank with 95 Ron

Is it hp at flywheel or whp?

I’ll leave it to tuner shop to decide on which turbo to use, but I suggested to have an earlier spool so they would consider as smaller turbo to boost at 7psi with possibility to increase boost if I’ll go with forged internals later on. What I’m trying to understand is what max boost is safe with stock internals and what HP and torque increase I will have with RON95 to decide if it’s worth the investment.

Jackson Racing says that it will add 50% HP with it’s supercharger kit which if I remember pushes about 7psi at 7000rpm and about 9psi at 7.5k. Then I believe these figures were not given for RON95 but higher octane or E85.

[tomm.brz]

don t look too much at data with american fuel... even 91octane is somewhat better than euro 95 ron
i meant 280hp at the flywheel

[Teppka]

Thanks. If I will go with forged internals, change injectors can I push the boost to have 300whp on 95RON? As far as I know 300whp is about the limit for automatic transmission to handle safely.

[tomm.brz]

not at all buddy, injectors are not needed anyway for a greddy stock, and if you change then anyway it doesnt change that it will never ever reach 300whp... i think even 300hp at the flywheel is difficult.
it Simply knock soon, you can t raise timing enough to reach that power
You d need to decompress the engine by rebuilding it

Or need more than 100Ron

[Teppka]

What about 98RON which I assume is 93AKI in the US?

[tomm.brz]

l98 ron is worse than 93oct,, even 100ron is not as good as american 93oct

95ron < 91 oct < 98 ron < 100ron < 93 oct < 94oct

with 100 ron normally i have seen around 300 to 330hp to flywheel
so 98ron a bit less

With good 100 Ron, not old or dirty, you can raise boost a bit lets say 9-10 psi and you could go around 350hp or little. over it, but that s tough
big injectors are not required unless you go over 12psi at redline

with 95 ron? no way. With 95 you shouldn t even put a boost controller or you make everything worse

[Teppka]

If that’s the case I wonder if it makes sense to invest in turbocharger on stock internals if I will gain some 50-80hp on 95-98 RON. At least it would get rid of torque dip and probably provide more toque in mid range where it’s needed.

[tomm.brz]

it is much funnier anyway and you can always put more octane somehow and have more power

[tomm.brz]

This is a conservative tune on 98ron and completely stock exhaust header back



this dyno reads about 190hp stock

[Sam86]

You probably don’t need injectors unless you’re going e85 as you won’t be making enough power on 95 for it to be necessary. Just need to make sure your tuner is utilising the direct injection

Don’t know what kit you’re going for but assuming you’re getting a kit that maximises power potential I’d say max around 290 wheel horsepower on the best kind of regular petrol and then around 335-340 wheel hp on e85 before you’ll need a proper fuel pump and valvebody transmission mods


I don’t know where the notion that the auto transmission can’t handle more than 300 wheel hp comes from. As long as you add a transmission cooler and have a good tuner it will be fine handling almost as much power as what the stock motor can take.

Most of the high HP 86’s in Australia (talking 400-500whp) all have automatics with the stock transmission just with a valvebody mod. Sure they don’t last forever on those cars but the point is, it’s good enough to handle at least up to 350 wheel hp fairly reliably

[tomm.brz]

Originally Posted by Sam86

You probably don’t need injectors unless you’re going e85 as you won’t be making enough power on 95 for it to be necessary. Just need to make sure your tuner is utilising the direct injection

Don’t know what kit you’re going for but assuming you’re getting a kit that maximises power potential I’d say max around 290 wheel horsepower on the best kind of regular petrol and then around 335-340 wheel hp on e85 before you’ll need a proper fuel pump and valvebody transmission mods


I don’t know where the notion that the auto transmission can’t handle more than 300 wheel hp comes from. As long as you add a transmission cooler and have a good tuner it will be fine handling almost as much power as what the stock motor can take.

Most of the high HP 86’s in Australia (talking 400-500whp) all have automatics with the stock transmission just with a valvebody mod. Sure they don’t last forever on those cars but the point is, it’s good enough to handle at least up to 350 wheel hp fairly reliably

yeah but he has only access to 95 ron, and euro 95 ron is worse than 98Ron... 290whp is impossible literally with 95ron

about injectors, it s 100% sure that he doesn t need them, a greddy will put out less than 0.5Bar of boost.. i have 1.1bar of boost with an HKS supercharger and still am with stock injectors

[Teppka]

What power can be achieved on 95RON if I’ll go to rebuild the engine with forged internals and reduce compression?