C. Ludwig

My personal opinion is to ditch the 6-port actuators all together. The rev range you describe is the same that we use for our ITS engines. We very, very rarely see anything under 6000rpm. The 6-port actuation just has no use. We remove the sleeves and that's standard ITS prep from Speedsource, ISC, etc. The mechanism creates a good deal of turbulence killing flow.



If we were allowed to do it under the rules I would remove everything, use Devcon at the end of the aux port to smooth it out, press out the actuator bushing in the intake, weld the holes up, and grind it all smooth.



You're looking for average power from 6000-8000 rpm. Nothing else should really matter.

23racer

I may have not been clear in my description. We are not using the 6 port actuators, however we have machined our some aluminum inserts with the same profile as the Pineapple inserts that will be securely located in the ports to provide a smooth transitional flow ramp. This past year we ran just the way you stated and were pretty quick, just need to go faster.



I am fairly familiar with ITS rules as I originally built the car as an ITS car. The last time the SCCA and the CASC ran a combined National at Mosport, we were running times that were less than half a second from the GT3 pole car and about 2 seconds faster than the E Prod pole car.



To win in our series I have to be able to run WC Touring class times on Toyo 225x15's. 2 years ago we were on the pace, but the Touring GT Championship is in the midst of an arms race and our fastest cars are a good match for front running WC cars (granted we have very few rules and our aero tends to be pretty aggressive).



On the free Bosch LapSim calculator, which has been a great performance predictor (only 2 tenths off my best times), I need to generate about 210 rwhp to be able to do a low 1:33 which is fast enough to be in the running.

C. Ludwig

Have you checked out Paul Yaw's site. He built a 4-port NA that's pretty well documented.



http://www.yawpower.com/sep2004.html



It made exactly the 210whp you're looking for.



Curious why you're not looking at going to a 4-port with a full bridge. Something like an E-Prod engine that will easily surpass you power goals? Does your rule book limit you to the six-port engine?

23racer

Sorta, I could use a 4 port if I wanted to. I just have 1 almost new S5 6 port (less than 6 hours from new), 2 S5's in pieces and 4 S4 6 ports. It is just a matter of economics as all of my support stuff and spares are for 6 ports. A 4 port would be considered an engine swap (not an original engine chassis combo) and bump me up a class to run with the Turbo's and v8's.

C. Ludwig

I see. Paul Yaw has also done a mondo six-port for E-Prod. Not sure how it ever turned out. Might be worth a call to get some info.

bill shurvinton

Oops. My mistake. Should have been 0.3d. The actual reflection length is 1/3 of the diameter above the bell mouth. As the bell is generally flared to up to double the runner diameter, this can become significant in the calculation stage.



The 15" I mentioned is just runner length and based a on a bit of reverse engineering off some dyno plots off a mazdatrix 6-port. Now the more radical the porting the shorter an inlet you need, but I reckon 12" will give you a peak torque just over 7000RPM.



Now thinking about it more carefully this may actually be good. If I am right (and I may not be) 12" will be better above 7000 and 15" below. Now will more power at 6000 RPM be better on the track that more at 7500. Dunno, but design the inlet so you can add or remove 2-4" to fine tune. There are gains to be had shunting the torque curve around 500RPM one way or the other.



Of course the inlet tuning is just 1 facet of the complete system, so the usual caveats apply.

23racer

Thanks a bunch for doing the calculations for me. I will build the manifold with a possible insert section where I can add and subtract a 2" to 4" section. You know that I would rather have the power at 6,000 rpm versus 7,500. It just makes the car more flexible for passing off line and if the loose nut behind the wheel makes a mistake.



Now I just have to cobble something up to determine packaging and the cold air box. May need to draw off the cowl to get it all fitted in and retain some level of flexibility.



Just excellent stuff and I will keep all of you informed as we work through the MS build and validation with Renns and the intake build with my crewchief. Try to back it all up with dyno runs and information of my datalogger.



I will make sure to credit all of you where possible. He!! this information should get me right in the ballpark right at the start and shorten the development curve a ton.



Again thanks and any other ideas would be appreciated.

Liquid Anarchy

be sure to post pics of your progress; I've been having a hell of a time describing an equal-length manifold design for GSXR TB's to my fab-guy. also; watch out for some stupid things like the waterpump neck and TPS

23racer

Actually, I have already dry fitted the system on one of my spare motors. It looks like it will clear the water neck no problem, especially if I have to extend the runners out 15 inches. I might have to work out a new cold air box that seals to the hood. Ah glass and tin work, gotta love it.



Keep in mind that my car is a race only car and I have removed all of the emissions stuff as well as the vapour recovery system and the AFM. Therefore I have a ton of room on the passenger side.



Regarding the throttle position sensor, I lucked out with my 'Busa bodies as they came with a full sweep TPS. Worked out the flange and lengths already, so I will cobble up something from paper towel rolls and cardboard to see if it all fits.



If it does we start welding!!!!

j9fd3s

just a small note. we ran a ps1 car (its in scca speak) fc in 04 and parts of 05, with a haltech, and we found the ecu helped power a lot in the 4000-6000rpm and the 8200+ areas. it didnt really add much peak hp, but it fattened up the curve a LOT. we were also running the stock internal motor to 9400 rpms, with no trouble, after we scattered the engine with the rev limiter