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so i ran across a couple of dyno sheets for the KSP FC3S, which is one of my favorite FC's ever. its also totally ridiculous
anyway dyno sheet one is the old spec,
its a 13B-T with 8.3:1 rotors, a pair of HKS GT3037S turbos, HKS GT intercooler (100m thick), a pair of stock oil coolers, HKS F Con V Pro, etc etc
Half Bridge Dyno,
vs full bridge dyno
they had wheel spin on the dyno, so that is the squiggle(!)
anyways RED is the power at the wheels, BLUE is the power loss (80hp!), Green is engine power
the light blue is Torks in kg. and black is boost
boost is the same, so you can see that the full bridge spools the turbos a bit quicker, but power is down compared to the half. top end power on the full bridge though is way up!
the other fun thing is that its a street car, so they put 20,000km's on it. stock seals too.
modified 8.5s, you can get them done from a number of sources; Japan (EDM), USA (CNC), Canada (CNC), likely AU and NZ, maybe EU, but I’m speculating on the latter areas not not knowing any place there specifically.
That CR is before any scalloping, clearancing, etc. I might be less inclined with BP and PP given the lower dynamic CR resulting from increased overlap, but fuel, application, power level, turbo response/sizing, etc. are all going to factor in.
that mod, face and side tip clearancing, intake scallops, and full lightening will get them down around the OE Renesis rotor weight. It generally includes balancing out the combustion chamber CCs and then also removes the rough OE casting surface of the combustion surfaces as well.
Here’s the EDM version from Japan, lower compression mod only:
Engine, injectors were 4x1000cc and the two more 720cc. since this was 2001, that is kind of what they had available
the ECU setup for the 2001+ car was the HKS F Con V Pro, which works. the previous setup (560ps) was a STOCK ECU, HKS VPC and an additional injector controller!
its pretty crazy, now; how much power people used to make with such primitive ECU's
^^for those with the ear to hear and the eye to see …
I’m not sure about it being mainstream. It is known and being done, but I was mostly ignorant on the details myself until discussing the subject of high vs. low compression with j9fd3s here several years ago. There’s not a lot of info on the forum about it other than a few mentions. So just sharing what I dug up having looked into it some.
Not entirely sure I agree with how they did it in the pics above. In general though, the EDM process in the one pic posted previously seems to focus on deepening and containing the combustion chamber tightly compared to the others I’ve seen. That can lead into some discussions about how one or the other might influence intake flow, combustion efficiency, and so on.
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the ECU setup for the 2001+ car was the HKS F Con V Pro, which works. the previous setup (560ps) was a STOCK ECU, HKS VPC and an additional injector controller!
its pretty crazy, now; how much power people used to make with such primitive ECU's
I bought parts from a guy once who had an old race car in his yard. It was a S4 Turbo II, and apparently the original owner modified it from new and raced it in the '90s. It had a 4" side exit exhaust cut through the bottom of the fender and a turbocharger larger than my head (and I have a pretty big head).
Apparently he raced it for years on a completely stock ECU, manual boost control, and the only way he tuned mixture was by swapping out injectors until the AFRs were close enough.
here’s a more recent version built by RS Pantera from the 2019 JP Auto Salon using the FD3 13BREW; twin GTX3076 turbos, HKS F CON V, ported out to Cosmo intake port sizing with Cosmo UIM/LIM intake manifold, their 8.3CR rotors -650 ps @ 18 psig boost
maybe "mainstream" misrepresented what i actually meant when i posted. i didn't mean to imply everyone is doing it. it just seemed to me that you rattled off a bunch of sources to have the work done in your response, and it gave me the impression that it wouldn't be hard to get that sort of thing done today - no matter where you happen to be.
i remember somewhere around 2004-05 i started trying to get info on machining the recesses. my intent was simply to polish and combat carbon buildup, but i also knew that it would affect compression ratio (at least static), so i wanted to get an idea how much it would, maybe even get a way to calculate it. it ended up leading me to meet a group of guys from the board in Minnesota (including Elliot/Turblown), but the short version of the story is no one seemed to know anything or anyone that knew anything. so, in that context, i used the word mainstream. i guess one of these days i'm going to have to pick j9fd3s' brain on the subject as well then.
Originally Posted by j9fd3s
... which is one of my favorite FC's ever....
now, to hear that this car's been around since 2001 is even more impressive. i can see why it would be a favorite.
As contrary as it may seem to post this, I’d suggest that neither of these engines is taking advantage of the full performance potential that the lower CR is capable of providing.
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i think i see what you're saying. i don't think its contrarian if the discussion/context is kept simply on the compression ratio versus the end result.
you might keep in mind that the Japanese tuners tend to start with what Mazda did, especially if we're looking at something old like this.
and we know what Mazda did, they had 7.5:1 rotors, a pair of turbos and a bridge port, and when RB put that in the FC, it went fast!
KSP car is wildly advanced in comparison, and makes ~200 more hp
luv it, stock apex seals (2mm or 3mm?).. Finally actual data: 9-10% power train loss.
Factory AFM? In a pressurized setup?
"lower compression = more boost = more power"
yep, stock seals, 2mm. the HKS Fcon V pro lets them pull the AFM out. its a cool ECU, because you can run it like a piggy back like the old Fcons, or you can run standalone.
it also lets you add and subtract sensors, which is pretty cool
its really popular in Japan, but its not really supported here
01-19-24, 03:10 PM
