Freefallin

Im pretty new to the FI world so plz bare with me.

Been searching for info on basically a 101 on compression ratios for boost but to no avail.

Im looking to build a boosted 1000+rwhp 408 iron block but have no idea what cr to go with. For one thing, i don't want it to be a pig off boost.

Any knowledge you can throw my way would be really nice!

THADD

iTrader: (12)

I'm 10.5:1 cr on a 347 and 22+ psi boost

Kip Fabre

Making 1000 + rwhp with 408ci will be easy with that many C.I. There are a few combination you could use but one would be 9.5 static. With the correct cam it will drive good and make the power you are looking for.

01transampower

iTrader: (9)

I live in Denver and we're gonna run my 408 at 10.3:1 or so to help with street drivability.

stevieturbo

And the most important question of all.....what fuel ?


And unless it's a 5 ton truck, I doubt even a 408 could ever be considered a pig off boost at any compression.

Freefallin

Fuel would be 91 and car is a GTO. Although not a truck it sure weighs like one.

stevieturbo

My car weighs similar to a GTO.

Ive had 346, 383, 403 etc in mine, and none have ever been a pig low down regardless of size or compression.

If you're looking to make 1000+ on only 91 octane, I'd say keep CR around 8.5:1

Zero_2_Sixty

My dynamic compression at 1000 is 9:1

MillsMotorvation

Had mine at 9:5, on 22psi no problem, just added heads I will be at10:3 should be way better! Out of boost it was always strong.

MUSTANGBRKR02

iTrader: (91)

Mine will be around 9.5-1 on a 427 going for 1500.

Cam72aro

iTrader: (28)

9.5:1 on my 408, ls3 heads, 20psi e85 and methanol. Car runs very strong out of boost and is a monster in boost.

Sales@Tick

iTrader: (3)

Dynamic or static? 9:1 dynamic is really high IMO for pump gas and boost. Are you running race fuel?

Most of the combinations we build are 9.0:1-10.0:1 static depending on the goals of the customer.

IMO the cam used will be more important for "not being a dog" than the compression ratio used.

Sales@Tick

iTrader: (3)

Bill,

Are you planning on using a 427 with that 88mm from BEP?

I would personally build a smaller motor for that turbo, JMO though!

Freefallin

Its funny how things snowball. Ppl don't usually mention DCR or SCR when they mention CR. So which one are they talking about when then say "im at 9.5:1 at 15psi".
Im guessing SCR.

F110Mech

iTrader: (2)

I would consider using methanol on top of the pump gas to have the ability to run higher boost

Zero_2_Sixty

I am running 93+meth

po feng

93 fuel ?

stevieturbo

6 year thread bump