Quote:
Originally Posted by SC2150
He is pretty correct on the additives as far as DI engines, but there are advantages to say stabil types for storage.
The reason a DI engine can run a higher CR w/out as much detonation danger is the fuel mixture on a port inj or carbed car is drawn into the combustion chamber on the intake stroke and through the entire compression stroke, so a glowing piece of carbon deposit can easily detonate prematurely. On a DI engine, the fuel is injected directly into the combustion chamber at 2-3000 PSI in the final 20% or so of the compression stroke so it is in the combustion chamber for milleseconds. That is why these will run fine on 87 octaine at that CR, and watch, I expect to see above 12:1 in the future. DI allows more power, better fuel economy out of smaller dispalcement....but that does not take away from the fact that it WILL run better, make more power, etc. on 93. We have seen this dozens and dozens of times on the dyno. We find some buy the VMax CNC patteren ported TB and see poor power....ask and find the owner has 87 in it. Run the 87 out and fill w/93 and see 8-15 rwhp more and far better response.
So no mythbusters needed. It is a personal choice.....they run fine on 87, just not as efficient as on 93.
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I always like reading your GREAT explanations Tracy.....
Those who THINK they know will NEVER believe.......
Those of US who have run and seen the differance BELIEVE......
