Midgrade Gas and twin turbos ...

[rfalker1]

I figured I would ask instead of just reading. So my build is near completion, a 68 camaro running 406 All forged Dart block. 9:1 compression. A FAST Sportsman EZ EFI with twin 71 mm turbo's without an Intercooler due to lack of an space and not wanting to cut on the car.


(its a pure street car . Overkill probably lol)


But since I am not running an intercool I will be spraying Methanol using a (snow performance rear mount kit) about 5 inches away from the blow throw style throttle body.
Snow claims that spraying the methanol will increase the Octane level by 25 points.
However it would only spray when the car starts to gain boost and will ramp up as boost increase.


So if Higher octane is only really needed when the engine is working hard to prevent detonation why would i need to run premium in it?


Couldn't mid grade (89) octane work fine for normal driving and when the turbos kick in the octane mixture will began to increase because of the methanol kit that is installed?

I dont drive very hard... its more of DD with a dumb amount of power.

[andrewb70]

With 9:1 compression, you can probably run 87 octane. The other key factor is timing. As long as you stay conservative with the timing, it will be fine.

Andrew

[CSG]

25 points only brings 87 to 89.5. We don't know anything about your cam or cylinder pressure but I would not do it.

[badazz81z28]

Funny how we still consider fuel "mid" grade, regular and premium. You need to use the min octane fuel that the engine requires to run properly...I put 87 in a my lawn mower. Any performance car these days requires 89 at a Min!

[Interceptor5588]

Should be OK if you have aluminum heads and keep the boost moderate (5-6 psi.) That should be plenty for a boosted 406 with street tires anyways. I wouldn't try to boost 750-1000 rwhp on 89.

[dontlifttoshift]

but why tho?

Seriously, even at 10,000 miles a year, you save......300 bucks?

[Turbo6inKY]

but why tho?

Seriously, even at 10,000 miles a year, you save......300 bucks?

This guy here.

How much did the engine cost?
Do you have a knock sensor and have you tested it well enough to know it'll react fast enough?
How much will it cost if you pop a head gasket?



Even a single detonation event can pop the gasket, break a ring land, or hammer a rod bearing so hard it grabs and spins. Any one of those events will cost you far more than running premium for years.

Any force inducted engine needs to run on the highest octane fuel you have available. Period.