Mistaken key stroke. Sorry!

 

Probably he went with the TME due to the rule restrictions in his rally series. The TME is a fast spooling, Mitsu factory homologated turbo and with a 30mm intake restrictor a larger turbo isn´t gonna do much good anyway.

 

on a 4g63 can i stroke it to a 2.4 and not having to move to a 4g63..

 

i ment a 4g64

 

It's true but potentially misleading, as WRC cars use a small turbo that is only effective at generating relatively low rpm power. As such, WRC engines are designed specifically to deliver peak torque at modest speeds (e.g. 3500 rpm). With sufficient cam timing, 10:1 CR is practical because the effects of valve overlap are most evident at low engine speeds (bleeds off some of that high cylinder pressure), so the effective cylinder pressure is more like that of an engine with stock cams and CR. This is why engines with big cams and high compression ratio can tolerate more ignition advance at low rpm.

If we install a larger turbo on the car and shift the power to the right such that the effects of overlap are diminished, the higher compression ratio will become a limiting factor with pump fuel.

Just FYI

 

Thank you Ted for the insights, but my point was more octane versus boost. For instance the 15GK that Mitsu uses or the IHI's that Subaru use are designed with high pressure ratios and short lifespan's in mind. My point was more that a motor breathing through a restrictor actually has less available oxygen no matter what the boost is and therefore would have less fuel and less combustive energy. You can survive at 3psi air pressure if the atmosphere is 100% oxygen because of diffusion of oxygen atoms is the same as 21% at 14.7 (This is why NASA did it until the ill fated Apollo fire). But it still stand that 44psi of boost on a 10:1 motor and 104 octane fuel is being done. I do question the exact composition of the "control fuel" that the FIA allows however.

I dont think anyone disagrees that if we were using a GT35R on an unrestricted motor with 10.2CR we would have some severe issues. WRC motors dont tend to run radical cam profiles as they arent conducive to keeping that torque in a nice broad powerband they just let AVCS, MIVEC, or whatever the variable valve control system is being utilised. But they use them just as you pointed out to bleed off some compression and alter the dynamic compression ratio.

The question about why not a GT30R, in open class the rules are in fact open in most areas. But as we are talking about you want the turbo that keeps the power the highest (at least in Subaru as I havent seen the actual dynosheet and failed to ask ACP last time I saw him) between 3 and 5K. It stems more from cost to rebuild aspect, suitable engine match, availability, and the ability to last whilst working with antilag. Sorry I didnt mean to cloud the subject and be potentially misleading either.

JB

 

Man I remember sbr from when I used to frequent dsmtuners. From building o.g. bullycars to building new style rally cars, you guy have come a long way. I remember back like 4 years ago when I and a whole bunch of friends ordered a whole bunch of stuff on a friends cc account right before christmas, you guys send us a christmas card signed by all the employees.. Don't mind my mumbling, I'm just reminessing. The moda looks really good.

Now using the 4g64 block out of the 2g n/t spyder dsm or out of the newer gen 3g elcipse? Do you get custom made longer rods and shorter pistons or do you punch out the block another .025 per bore and get O/S pistons made for it?

 

2.5L....hmm hmm yum

 

LOL I remember those cards too! Hahahah, those were the days. Thanks SBR for all the fond DSM memories =)

 

The extra displacement comes from the 102 mm crank, stock length rods, 87 or 87.5 mm bore... Yes, we use the 3G block for the build up on the rally car -

Thank you for remembering the good ole days - that rocks, look for us in a 1G TSI at the strip soon... lol... going to bring it back OLD SCHOOL.

Mike Huml
Slowboy

 

Thank you guys, you made my week - long live DSM's.

Save-the-dsm.org - is this up yet?

Mike Huml
Slowboy

 

any graphs yet?

 

any graphs from an old post ?

 

i know this is old, but i have a question for SBR.

what happens if you use the 100mm crank and bore it to a 2.5L?