Thoughts on 8.0:1 compression using E85 fuel

[momento1]

digging around the forums here i know a few people have suggested that 8.5:1 compression is probably the lowest they would go when tuning with E85 fuel

my dilemma is that i can get a extremely great price set of wossner pistions 81.5mm but they apparently are a 8.0:1 comp piston

let discuss the possibility of an 8.0:1 comp piston with stock length rods and E85 fuel

pros and cons??

[Thuppu]

Well, I guess 8.0:1 isn't bad if you aiming on 1000+hp...

[momento1]

lol...
sorry i should have specified... im aiming for no more than 400kw atw in the long term (~540hp atw)
so possibly 600-650hp roughly with a GTX3582r

[diesel des]

Go for it the difference in efficiency is tiny.

[speeding-g60]

i run 8.5:1 with E-98 just fine with tons of boost and awhp's.

i wouldnt blink, it just gives you that tiny bit more freedom in tuning.

[quattro-nick]

i run wossner pistons 81.5 mm with stock length rods, compression ratio 8.0:1 ,gt3076r A/R 0.82 turbo,stock head and cams,tubular ex manifold
full boost (2bar) on 4000 rpm with pumpgas 98'

[prj]

On E85 if you are not going to 700+ hp then you will lose power dropping CR...

For your target and E85 just use the original stock pistons. They have the perfect CR for your power target and they are strong enough. If your block is getting rebored then just buy original oversize ones.

You win nothing by running aftermarket pistons in this scenario. You do not gain any tuning leeway either really, as you can run MBT all the time with the stock CR, it won't knock. Once you go closer to 700 and above it, you will start hitting knock at peak torque with the stock CR and E85, so then you will need to drop the CR somewhat to maintain peak efficiency.

That all said, it's not like you're going from 9.3 to 6... so it's not going to make a WORLD of difference, probably a few dozen hp and a bit less torque down low.

[vti2]

On E85 if you are not going to 700+ hp then you will lose power dropping CR...

For your target and E85 just use the original stock pistons. They have the perfect CR for your power target and they are strong enough. If your block is getting rebored then just buy original oversize ones.

You win nothing by running aftermarket pistons in this scenario. You do not gain any tuning leeway either really, as you can run MBT all the time with the stock CR, it won't knock. Once you go closer to 700 and above it, you will start hitting knock at peak torque with the stock CR and E85, so then you will need to drop the CR somewhat to maintain peak efficiency.

That all said, it's not like you're going from 9.3 to 6... so it's not going to make a WORLD of difference, probably a few dozen hp and a bit less torque down low.

To how much HP would you recomend stock C/R on 98 octane?