500Hp Rb25Det Compression Ratio?

[ricardo.benin]

Hi guys did a bunch of searching and can not find any direct info on piston compression ratios as I am going with forged pistons. So what compression ratio do you guys recommend for a 500hp rb25det street car with a gt3582r turbo.

Thanks

[boostn0199]

9:1

[ricardo.benin]

OK great standard

[Blackkers]

What fuel are you going to use?

[ricardo.benin]

I am going to have to run 93 octane gasoline as there is no e85 around but the car is going to be a street car.

Thanks

[Ben C34]

How experienced are you building engines?

First time? Based on the incredibly vague first question that's what I assume.

Comp ratio is a compromise relating to many factors. Boost, fuel, cams, head design etc.

Certainly not as simple as what's the best.

Although 500whp isn't that much so stock comp would do it with that turbo and fuel I imagine.

[ricardo.benin]

Hi Ben c34 yeah I am new to these engines as I have only owned mazda rotaries (complete different animal). But from the info I have gathered I have been told a stock cylinder head should be ok for what I am doing but I need to upgrade rods and pistons as well as mod crank snout for the longer oil gear. But I am probably going to stick with stock compression ratio.

Thanks

Richard

[XKLABA]

93 octane ?, are you in the states ?

If so do the conversion, IIRC your 93 is our 98

In which case I'd say 9:1 with a stock head and the right turbo will easy see 500hp

[ricardo.benin]

Yeah I am in the states and the places that sell en are like 45 minutes away. But thanks for all the info. Btw When using the stock head and stock head components what parts are known to have problems and If I did want extra insurance I am assuming just install valves and retainers.

Edited October 19, 2014 by ricardo.benin

[GTSBoy]

New or reconditioned (at least cleaned out) lifters are nice.

[ricardo.benin]

Hi I am having the head reconditioned for sure. Then I was going to clean up cast marks in ports but mainly water jacket holes in cylinder head and I was thinking of running a line from cylinder head to sump. And widen the oil galleries on head and block.

[discopotato03]

I think a GT3582R will be quite laggy on an RB25 with the std CR on your 93 octane . In the US with things like the 3076 and 3582 HTAs available I think you can do better .

With non standard manifolds the EFRs are probably better again particularly on pump gas because their turbines tend to be larger in relation to their compressors than most other turbo suppliers . You should be able to get 500 from a 7064 or a 7670 with better turbine response/transients than most other makes .

Having less inertia and exhaust restriction is the go IMO .

A .

[GTSBoy]

Hi I am having the head reconditioned for sure. Then I was going to clean up cast marks in ports but mainly water jacket holes in cylinder head and I was thinking of running a line from cylinder head to sump. And widen the oil galleries on head and block.

I was talking specifically about the lifters.

[ricardo.benin]

Yeah I am for sure going to have the lifters reconditioned.

Thanks