84 replies to this topic

[paulf-cam]

supercharged engine, if your camming, what's proven to be good on an NA cam setup can be good for the blower setup.

I thought the opposite was true, because of the scavenging effect NA cams tend to have which you don't want on a force fed engine?

Something to do with valve overlap IIRC...

[markv]

Although to get the best out of a system for a boosted application* I suspect you should be looking to go to a terminal size of 2.5" - 3" and all the off the shelf ones for the NA are 2.25" IIRC which means you should prob be looking at a full custom system, or mate it to a back box off a turbo, IIRC the Miltek turbo back box is 2.5" and Cheeky has a 3" Blue Flame.

Are there complete 2.5" exhaust systems for the NA? I know the NA Milltek is 2"... A 2.5" for a compressor setup is probably a must. And will be no issue with the standard manifold as it is more then 2.5" at its exit..

Mark

[Winstar]

Are there complete 2.5" exhaust systems for the NA? I know the NA Milltek is 2"... A 2.5" for a compressor setup is probably a must. And will be no issue with the standard manifold as it is more then 2.5" at its exit..

Mark

I don't think there is one that's bigger than 2.25, the problem with the current manifold is not the exit as that is designed to spread the flow over the precat. However the runners are quite small diameter.

As promised, here's the first scheme of my 4-2-1,it's runner's 2-4, but I'm going to change the primaries around to give bit more room for the secondaries. You could use a similar scheme for the secondaries to do a 4-2-1 similar to the Weapon R I posted. Oh and excuse the collectors they a PITA to try and model



Oh and I was board so a knocked up a scheme for a short runner primaries pairing 1-4 and 2-3, these are 1.75" and 286mm long, equal length*



*Yes I am a sad engineer

Edited by Winstar, 17 May 2007 - 01:26 AM.

[speedster]

supercharged engine, if your camming, what's proven to be good on an NA cam setup can be good for the blower setup.

I thought the opposite was true, because of the scavenging effect NA cams tend to have which you don't want on a force fed engine?

Something to do with valve overlap IIRC...

Yup, correct, if you run big cam overlaps on a supercharger setup you can end up dumping a portion of the AF charge straight into the exhaust ports and mani. That said, just like an NA you can use a certain amount of cam overlap along with the negative pressure waves in the exhaust system to efficiently scavenge exhaust gases. Something like the piper cams might be suitable, they ain't too crazy (if I recall correctly). You can make fine adjustments to the overlap durations by using use vernier pulleys. Which reminds me I need to get details of my cams from dude

Winstar, cool, what software are you using? Here some 2D pictures I jigsaw'd together.

clicky

clicky

clicky

clicky

Edited by speedster, 17 May 2007 - 03:58 AM.

[Winstar]

Winstar, cool, what software are you using? Here some 2D pictures I jigsaw'd together.

My work's laptop runs ProE, the 4-1 was just a quick lash up I could prob get more length in the same space with a bit more tweaking and increase the radii of the curves from runner 1. It's pretty simple once you know where you start and finish you just conect the ends with a flexible curve that pull it into shape, then measure the volumes to make sure they are equal length.

Edited by Winstar, 17 May 2007 - 03:22 PM.