Barwick

Which would be best for running a standalone? Help me decide:

S5:
Lighter Rotors
Higher Compression (good & bad)
Electric OMP - Need something to control me
Better stock turbo

S4:
Heavier rotors
Lower compression (good & bad)
Mechanical OMP - no standalone intervention required
Not-so-great stock turbo

What else am I missing? The car is PROBABLY going to keep the stock turbo (and maybe stock intercooler, not sure) on it until I upgrade the entire engine to a 20B (I'm getting a standalone that can control a 20B, and upgrading the rest of the car appropriately).

As it sits right now the car is an S4, if that helps any.

Josepi

S4 block/omp, everything else S5.

Barwick

any reasoning behind that? By block you mean engine internals also I guess

Josepi

Safety of lower compression. Safety of OMP. Everything else S5, ie manifolds, turbo, what nots.

Barwick

ok, one opinion noted, sounds like it would just be easier in my case to just get an S4 J-spec

eViLRotor

iTrader: (2)

I have an S5 block I like the higher compression down low.

I don't run super high boost (15 psi max) so I'm not too worried about the safety provided by the lower comp S4 rotors.

Plus, we have 94 octane gas, and I premix so no OMP.

j200pruf

iTrader: (4)

I would go with a S4 front cover on a S5 engine. The S5 housings are stronger I believe. And Ihave read in quite a few places that the S5 rotor housings have better plating than the S4 rotor housings had.

j9fd3s

iTrader: (3)

its a little easier to get the injector plus for an s4, but other than that it doesnt matter

Sesshoumaru

iTrader: (1)

S5 bock.

If your probably using stock turbo/ic there is no need for lower compression to keep you safe.

you can premix and not worry about it or just swap a mechanical on with the frong cover.

Plus the better turbo (but can beswapped either way with front cover)

Sponge Bob Square Pants

S5 block is far superior to the S4. Infact, the S5 is a lot closer to the S6 core than it is to an S4. Upgraded internals (ie: stationary gears), better porting.

I agree with Sesshoumaru, if keeping the stock turbo/ic, then you won't be pushing lots of CFM with big boost levels, so the higher compression rotors are actually BETTER for you.

I can't think of 1 reason why the S4 would have advantage in this case.

Rotary Racer

S5 block, S4 rotors, and if you "have" to still have the oil injectors run the S4 front cover. Otherwise keep the S5 one with a block off plate and run premix .

- Dana "thats what I got"

NZConvertible

Unless you're aiming for really high numbers, there's absolutely no reason to use low-comp rotors for "safety". Higher compression makes an engine torquier and more flexible, and overall perform better. If a 0.5 difference in compression makes a difference in engine safety, you need a better tuner.

Barwick

you know another thing I wasn't even thinking about until recently, is the S5's are on average 2-3 years newer as well.