Building a 2.4L and have to decide between using GSC S2's versus S3's (MIVEC).

Primarily a street tuned car on 94 octane with a few max dyno pulls on E85.

Turbo is likely to be the HTA3582 0.82a/r, to be tuned at 26psi on pump gas.

I've heard the S3's are a great choice for LR2.4L builds, but being that I'm just running a traditional rod and piston setup on the 100mm stroke, I'm not sure if perhaps the S2's are still the better choice of the two?

Looking for some opinions! Thanks

 

What about R2's? They are like S2's but made for stroker applications

 

Not sure to be honest; is my engine build even technically a stroker? It's just 150mm turbo tuffs, standard size, 100mm stroke with Wiseco pistons 9.5:1

 

Watch this video, it should help.

 

So it would seem:

LR2.4 = higher rev, higher max power; better suited for drag race setup, less vibration at idle, motor will last longer when revving high often

SR2.4 will have lower end torque benefits, which maybe is nicer for daily driving...but that vibration doesn't sound very good Does anyone have any comments on the vibration of the engine with GSC S2's? I won't be running balance shafts to begin with, so this is a bit of a concern

EDIT: I should add, this video explores the differences on an EVO 8, whereas I'd be using the EVO 9 with MIVEC... not sure how that changes things...I'd imagine it helps with the transfer between low RPM to high RPM where for normal use it's more forgiving / has less vibration...

 

R2s for a 2.4 would be my recommendation.

 

Thanks

 

Are the R2 mivec camshafts as aggressive as the S3's? How exactly do they differ from an end-user standpoint? I can read the details on paper, but when tuned for daily use, how might they be different in varying driving situations than the S2's and S3's?

I haven't been able to find too much practical use information on them. From videos and what I'm reading, they seem very harsh actually.

 

I have them and love them, they are basically the same lift as S3 but the duration of S2.. so you get the best of both worlds, they are stroker big turbo cams and have great manners. honestly anything between R2 or S3 will have a 20hp difference if that. so if you want a super nice idle/driveability then S2 are nice, otherwise your going for power then R2 and S3!

 

Is your build a LR2.4?

I'm being told by a few tuners now that the S3's are actually better suited for 2.4L builds (arguably a smoother cam than the S2 even), but where I'm a bit unsure still, despite their advice, is these are all specifically LR2.4 builds, whereas I'm just running a standard 2.4. I don't know if that matters much, if at all.

 

Harsh is the exact opposite of what the R2 is. One of the videos of the first Auto Evo was idling on R2s, sounded well mannered to me.

The R2s are almost invisible in a MIVEC motor, the S3s have some areas in idle and light throttle that they give up to the R2. The ramp rate, duration at 1mm, and lift exceed the S3. They are meant for a stroker motor and a sub 9,000rpm peak power rpm range. The S3 has its place if you are running a 2.4 over 9,000 but since that is exceedingly rare and would require a 72mm or larger I wouldnt suggest the S3 over an R2 initially. In an VIII I feel the S3 may be a little smoother at idle because of cam timing but not much, again the R2 is very well mannered for the size of camshaft you are dealing with.

On a 2.2L I can see going either way, 2.4 definitely doesnt need S3s to be happy.

 

The R2's quicker ramp rates and slightly shorter effective duration make it preferable (IMO) to the S3 for <8500 rpm 2.0L applications as well. Faster ramp rates and shorter rod/stroke ratios (e.g. 150mm rod) improve low speed VE, all else being equal, and that means nominally better street manners.

The quicker ramp rates are more demanding on valve springs, and one would be wise to adhere to GSC's recommendations. OE springs should not be mentioned anywhere in this discussion.

The R2 also give slightly greater lift than the S3, but that's meaningless with a factory head. Both of these cams require a thoroughly, competently ported head to deliver their true potential.

 

Well it sounds like the R2's are the best cam choice then for my build and fortunately more readily available to purchase, it would seem, over the S2's which are in particular on back order for 10 years or something.

Thanks for the information Ted B, JohnBradley, chamelieon, e_kobz and AWD_Launch.

 

I have R2 in my 2.4LR and it spools fast, idles like stock.