Originally Posted by Boris_Petrov (Post 3193116)

To start this off I live in Europe and I don't have access to e85. With the GTX2867R I'm going to order I'll be looking to make around 380 horses. Some people tell me - stick with 12.5 compression ratio and run 100 RON, others - go for 10 or 10.5 comp and run whatever gas you want. I'll replace the con rods for sure, but my question is if I can run this much power on this gas with stock comp or should I lower the compression and go for more boost. Also I had read that e85 has a 100-110 octane rating and 100 RON obvioisly has 100 oct. so it shouldn't make that big of a difference. Maybe. If it does feel free to tell me!

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Originally Posted by 86TOYO2k17 (Post 3193121)

100 ron is 95.75 octane

E85 is 108 octane



but 95.75 is still pretty high octane. No issues with using that. Wont be able to run as much timing and boost though. Not sure you'll hit your power goal without something higher.

Originally Posted by tomm.brz (Post 3193133)

i would keep stock CR and boost around 0.9-1 bar.. if you want more hp with 100ron maybe should think of bigger turbo
would be huge difference with e85 but i'm like you, only 100ron in italy

Originally Posted by tomm.brz (Post 3193143)

if you remote tune with good master tuner and put a wideband I would not worry
if you lower CR you lose hp and then you put higher boost to compensate.. with that particularly turbo i would just keep stock CR, you said you build the motor anyway, with built engine i would personally go to 1Bar .. you re gonna be knock limited anyway by the fuel... don t know what hp you re gonna get, bigger turbo maybe would help and the high CR helps with the lag

Originally Posted by Boris_Petrov (Post 3193124)

So do you think I should go for 10.5 comp ratio?

Thanks for the reply by the way!

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Originally Posted by 86TOYO2k17 (Post 3193145)

I am not the engine building guru. I am sure some more people will chyme in with more information in a bit.

but,



Lowering the CR will allow more boost and timing compared to higher CR resulting in more on Boost power. However off boost like in normal daily driving the lower CR will have a lot less power, less fuel efficiency, and feel "laggy".



Also you need to look at your blower and at what flow rate or boost pressure it is the most efficient at. and pair your blower size and CR to your power level goals for maximum efficiency.



Also some other options if E85 isn't available is octane boosters like Boostane (half a can should get you to 100 octane per tank of gas) or a water meth kit (a little pricey to setup at first but then pretty cheap after the initial investment).