Alldaybored

iTrader: (2)

HI guys Im looking to build a autocross engine pretty much and i want to get and much power through the whole rpm band and a nice strong flat torque band

the goal hp #s i want to try to get is 400 to 350

I think ill do a large street port
850 prim and 1600 sec
a gt 35r turbo (not sure on turbo yet)
a v mount rad and intercooler
haltec e8

thats all i can think of right now

but any help would be great and which mods should i do first? kinda wanna keep my car driveable during all of this

again thanks for the help guys im trying to plan out this

Alldaybored

iTrader: (2)

oh and the engine is a s5 turbo 2

BLUE TII

iTrader: (9)

Your plan sounds good but, I would NOT do a large streetport.

My set up was also a fast spooling turbo (positive pressure from 1,000rpm, full 14psi boost by 3,400rpm) and large streetport (intake open ~24 deg close ~7- deg, exhaust cut down and up a smidge) and it was very hard to auto-x.

I had to work hard to keep it OUT of the powerband that started at 5,000rpm on anything but a long straight or it was sideways city. Regardless of the early turbo spool the large ports made the power hit too hard and too late in auto-x and even hillclimb.

My new ports are fairly little (open ~24 deg close ~55 deg) and I will close my exhaust very near stock while still opening early for the quick spool of still combusting exhaust gasses.

I am hoping to exploit the quick spooling turbo with this small port set up for a more progressive controllable and broad powerband.

dpf22

Currently the fastest FD in SSM this year is MCKee (think I spelled it right?) He is running a 9.7:1 compression FD based motor with a gt30r (GT3076R) and makes around 400whp with about 18psi. Extremely fast transient response. He had a small back t3 gt35r last year but is much faster this year. As far as the motor. Would suggest a very small port if any. Stick with cleaning the stock ports up and use FD rotor housings if you can, they match the exhaust sleeves better and have a better coating overall. Hope this helps.

I have something completely different in the works for my autox FC, but I won't post anything till its done and I have some results.

ARD T2

iTrader: (22)

Are you talking about Andy McKee?

Rishie

fredox19

iTrader: (8)

What about a BPort wouldn't that spool the turbo faster and sooner? Just guessing. Or is that only for drag application?

dpf22

yes, andy mckee. Seen that FD in action this year when I went to the prosolo in Wendover Utah. Spoke with him and Strelneiks (sp?) about their respective setups.

No, a bridgeport would be very unadvisable given the nature of the top ended port. Yes they will spool the turbo slightly sooner, but they create less torque in the bottom end because of the inherant lack of volumetric efficiency below 4000rpm. Too much overlap. This is why I suggest stock cleaned up ports.

BLUE TII

iTrader: (9)

What about a BPort wouldn't that spool the turbo faster and sooner? Just guessing. Or is that only for drag application?

No, a bridgeport would be very unadvisable given the nature of the top ended port. Yes they will spool the turbo slightly sooner, but they create less torque in the bottom end because of the inherant lack of volumetric efficiency below 4000rpm. Too much overlap. This is why I suggest stock cleaned up ports.

The relationship between the power curve and overlap is complex in a rotary.

Naturally aspirated with a very low restriction (race noise levels) exhaust a peripheral or bridgeport motor (with the same intake closing timing and similar port volume) will make more power from idle to redline compared to a side port.

I am saying this after looking at dyno charts from the development of the Wankel engine.

If there is any restriction (like a muffler or a turbo) then exhaust dilution in the intake phase really hurts power in a hight overlap rotary, especially in the very low rpm range and very high rpm range.

Now as pointed out a bridgeport will spool a large turbo faster than a streetport, but still make less power in the low end. Boost doesn't make up for the fact that the intake charge still has exhaust gas in it from overlap in this case...

So, how about a positive displacement supercharger on a mild volume/closing bridge or peripheral port? Have seen one running at our Auto-X and it has an awesome power band!

Lots of custom fabrication required- that where it gets ugly or really sexy!!

quattro4now

Whats he using for fuel and/or auxiliary injection? GuitarJunkie28 built a FD motor like that (rotors and turbo) and he was limited to 12psi due to EGTs being 2000 degrees with pump gas.

dpf22

Race fuel only. Trailer'd to and from events. I believe he runs something along the lines of c16. This is not a street FD. Full fiberglass front, no headlights, cage. No aux injection