Power Predictions, please

[skivittlerjimb]

9.0 - 1 compression, fresh full bottom end rebuild
880 cc injectors
Walbro 255 lph fuel pump
3G MAF
DSM Link
Brode FMIC w/2.25" piping
Heavily ported Big 16G with custom o2 housing and 38mm flapper door
Ported Evo 3 exhaust manifold
2.5" catless turbo back exhaust
stock cams (would have loved HKS 272s, but...)
stock 1G BOV
stock intake manifold
93 octane

Other, non-power related sundries- Moroso oil pan (maybe), Visteon radiator, 90 oil cooler set up

So, hopefully to be dynoed at DSG next week... who wants to guess at the wheel HP and torque numbers?

 

245HP and 225FT-LB

 

[ktmrider]

How much boost are ya targeting?!? Numbers will vary wildly w/o that tidbit.
Hard part will be tuning for that CR, supposedly makes adjustments very sensitive.

 

[thecman02]

stock 1g..... as in uncrushed?

If that bov isn't crushed it'll probably leak and you'll get about 17 psi and probably 250ish hp.

If it is crushed and holds fine I think you could get around 290ish WHP with a pretty good tune.

 

[thecman02]

Ohh and that's estimate from me is around 22ish psi and a top timing around 17ish, but this is just all guessing.

 

310hp and 285ft lbs. @ 22psi

But who cares!?

All that really matters is response, Safe WOT A/F, good cruising A/F for MPG, and no knock. Thats all I'd be really worried about.

 

[Brianawd]

300 on pump and 360-380 on race with the boost turned up

 

[OldHairyBastard]

240hp 235tq

 

Quoting Brianawd:
300 on pump and 360-380 on race with the boost turned up



Yeah.

I have seen 16g stock CR cars make 300 so with that compression 300 should be safe and attainable.

 

[skivittlerjimb]

Targeting every day PSI around 18psi. The 245whp number seems low to me, but I'll defer to the knowledge base here.
Is the 16G the limiting factor most of you are looking at? IOW, would the bump up to a 20G or other sort of turbo
that flows more be a good match for the 9.0 compression? Or is it as simple as crushing the BOV to hold more boost?

I went with the higher compression to get the best throttle response possible for track and hillclimb and street use,
as for now this car will remain dual usage. Really I'm not that worried about peak power but rather safe and usable
power. This car will do a fair amount of digging out of slow corners in 2nd and 3rd gear and I want early spool,
broad torque curve, and not try to push 25+psi to do it. Still, it would be nice to have the 300whp number to hang
a hat on, but really the number is pretty immaterial.

-Jim B.
280/1000

 

[thecman02]

Well... I will say that your car will be great for what you want it to do. I'd just keep the 16g by the sounds of what you are shooting for. 300whp is a goal that can be achieved with you set up, but you will have to crank the psi up to get there. I just don't believe at that psi with all the other things in your build that you'll be able to get enough air into the engine without going to a higher pressure than 18ish psi. Mild cams like 264's won't hurt your low end torque and should raise your horsepower/VE be a decent amount. Then with the topend flowing more air the turbo doesn't have as high a psi... though it is still working harder because its got to spin faster to keep up with airflow demand.

Pretty much I would say don't worry about running high boost. As long as you have ARP headstuds/ good FMIC/ healthy 16g you should be able to hit 300whp with confidence. You might have to be around 23ish psi though.

To have large HP numbers with low boost you need lots of $$ in making your engine more efficient. Sheet metal intake manifolds... cams... porting... polishing... high rpms.... big lb/min turbos.

 

[skivittlerjimb]

Good knowledge. Makes sense, too. I'd wanted HKS 272s but it didn't work out and we ran out of time. After a few months of events on this set up I may step up to them still.

Alex did screw it together with ARP hardware. The Brode FMIC may be a restriction at some point but I'm doubting it will be at 300-350hp levels. I'm hopeful the trick rebuild that was done to this 16G (it used to belong to Bob in Chicago who had it fully rebuilt before selling it to me) will allow it to flow quite a bit more air than a regular Big 16g, and that the O2 housing w/38mm flapper will keep the boost creep in check. Next steps would be some valvetrain work to allow higher rpms and port work to the head, and of course I could always go bigger on the turbo, but not at the expense of quick spool. Any long term recommendations on quick-spooling, road race oriented BB turbos I can drool over for the next year or so? Would like to remain internally gated, but then now I'm stepping outside of my turbo knowledge base.

-Jim B.
280/1000

 

[thecman02]

There was a guy on the forums selling the perfect turbo you were looking for.
SBR GT-11

I was interested in it but it was low on the priority list. Fast spooling turbo, bolt on, internally gated. I myself don't know if I'd buy much from SBR though because they've had a shaky history as a distributor/manufacture.

Any 50trim in ball bearing form or around that size is about ideal for road racing I'd think... there are people with actual experience on here that can tell you though.

 

[thecman02]

Here was the post I was referring too...

FS gt-11


So when/are we going to get the hard numbers on what your car puts out?

 

[skivittlerjimb]

Survey says... 238whp 250tq at ~16psi - many thanks to DSG. /ubbthreads/images/graemlins/worthy.gif

It'll be nice to see a graph if Alex has one handy. Given that this is what stock STi's usually read on this dyno, I'm pretty happy considering the relatively mild mods this car has otherwise. Not sure if Alex worked it out or not, but the modified Big 16G with Bullseye housing might be responsible for some erratic boost and also might give out a little early whereas my old, plain-jane Big 16G made pretty smooth boost right straight through redline.

Longer term plan is 3" exhaust, bigger front mount, 20G or perhaps something a bit more exotic, and HKS 272s. For now I'm going to simply be a very happy GVR4 owner, and drive her as gently as and infrequently as I can this winter. Some attention still needs to be paid to particular areas like suspension bushings, gauges, and of course getting the racing buckets and cage in, but otherwise I'm feeling like I have a nice foundation for a track, hillclimb, and hopefully Targa Newf. car some day.

 

[kartorium]

Sounds like at the 22 psi level you would have been right around what most people were guessing...somewhere at 300whp or maybe even a tad more. /ubbthreads/images/graemlins/smile.gif

Congrats, and I hope the car remains fun and quick for years to come with that new motor!

 

Get an external wastegate. That bullseye housing doesnt seal real well and wont hont consistent peak boost. Looking back at my old 16g that was likely the issue. I went to a PTE SCM5031e and loved it.

 

Quoting skivittlerjimb:
Survey says... 238whp 250tq at ~16psi - many thanks to DSG. /ubbthreads/images/graemlins/worthy.gif



awsome man! congrats.. i hope to bust 300whp out of the water... kd stg3, 750's, fp race manifold, 3in tbe, @ 20psi... she hauls.

 

[Brianawd]

Quote:
the modified Big 16G with Bullseye housing might be responsible for some erratic boost and also might give out a little early




/ubbthreads/images/graemlins/hsugh.gif You don't say. Maybe now people will learn that those housing suck balls

 

Might I ask why you only tuned for 16psi? I bet with your set up 22psi could have been very do-able on pump gas.

Good luck!