10:1 compression ratio Is it necessary to use E85?

Can use to 98 octane?

 

[QUOTE=krys88;11957752]大家好。我正在建造我的備用引擎。它是 4g63 塊，我最大的問題是你們會推薦什麼壓縮比。我的計劃是使用 Wiseco 活塞，他們唯一的選擇是 9.0 壓縮或 10.5 壓縮，沒有中間值。這具引擎將僅與 e85/競賽汽油一起使用，根本不需要泵燃料，但在大渦輪增壓器上將看到 40+ psi 的增壓。你們會選擇10.5還是9.0的壓縮比嗎？我目前的引擎是 10.5，並且得到了很大的提升，並且在過去 4 年裡到目前為止運行良好。謝謝!
10:1 compression ratio Is it necessary to use E85?Can use to 98 octane?

！

 

Running lower octane fuel on higher compression motors limits the safe window for the motor on that fuel. If you are only going to run a pump gas like 98, I would build a lower compression motor to give more wiggle room for the health of the motor at the expense of a little off boost power.

 

I think it's more about the tuning and how good the tuner is. I ran 12.5 in my 2.4 on flex fuel for the longest time with no issues. The problem is finding a tuner that will tune the car . I'd be more worried about that then the grade of fuel, but I agree lower compression will make everything much easier.

 

Yea, the tuning is what I was getting at with the safe window. A good tuner can make the higher compression work with lower octane, there is just a smaller window for a safe tune.
Lower compression is the move if you are planning a solely pump gas motor though. Why make it harder than needed lol.

 

Yep and that's how you can judge if a tuner is worth a **** or not either. If I called and get a that's to high i don't wanna tune it that tells me he isn't a very good tuner. Most tuners I have dealt with are pnp runers meaning they all have a certain setup they want to sell people cause they load the laptop, load the map and it's 90% close to power runs and that's it . Tweek a few things, make some power runs done. A real tuner wouldn't care what your running they will take the time and do it right. Start from scratch and make all the powers with whatever setup you have

 

Unless your going to run methanol , your life will be easier under 9.5:1 on these cars.

 

[QUOTE=tsefung124;11982772]

10:1 compression ratio Is it necessary to use E85?

Can use to 98 octane?

10.5:1 is my favorite one. Engine is more alive. Make sure timing and boost is right

 

[QUOTE=krys88;11982815]But where I am there is no E85

 

Octane limited is still octane limited though. 91 or 92 out west you get handicapped really fast with compression ratio being too high. Its not that it cant be done but if you are gonna build it and want to run pump the gain from compression is only 4% per full point, turn the boost up and have a more flexible engine build. I have tuned engines in the 7:1 range and made just as much power as a 9:1, even between an 8.5:1 and 9:1 there is a lot of extra cushion for fuel quality.

 

I remember your old posts about this and it's always stuck with me.
I'm building a 2.0 156mm long rod setup with "stroker" pistons, so it ends up being around 8:1 compression.

 

It is my current suggestion for any road race car actually. Here is a dyno sheet from a 2.0L, 3582, S2, etc. (normal) with "guess the compression ratio". The car was dyno'd on normal Chevron 92 octane a mile from our shop where I have gotten fuel for the last 17 years. The AFR at the end was the sniffer blowing out of the exhaust but other than that I think it gets the point across.