with a twin VNT-25 system can i have more cam overlap than a standard turbo?

[T-Punk]

From what i understan about cams (which is something im kinda weak on in my knowledge base) i want a little overlap as possible when running a turbo. The reasoning i have heard is because of the added backpressure in my exhaust from the turbo. My question is, could i run a more agressive cam with more overlap since i am going to be running twin VNT's (which dont tend to add as much backpressure as a conventional turbo) or should i just use a standard turbo cam?

[Tiago]

u will still have back pressure. 2:1

[T-Punk]

alright, i was just curious.

[nocutt]

Originally posted by T-Punk:
From what i understan about cams (which is something im kinda weak on in my knowledge base) i want a little overlap as possible when running a turbo. The reasoning i have heard is because of the added backpressure in my exhaust from the turbo. My question is, could i run a more agressive cam with more overlap since i am going to be running twin VNT's (which dont tend to add as much backpressure as a conventional turbo) or should i just use a standard turbo cam?

Unless you are trying to go beyond 10s, the stock cam is plenty enough...focus on the dynamics of the turbo and everything else around it...the later you get to crossover the better!!

[T-Punk]

i have a vert... i think it would be suicidal to go past 10's but thanks for the info about the stock cam.

[Arctc Wolf]

Cam selection will depend on the powerband and turbo characteristics. if it has a monstrous exhaust housing compared to your application, then a little more overlap can be accomodated. The main worry is reversion from the turbo back into the motor, which is why cam's are usually designed with minimum overlap possible. Mods that will allow more overlap are:

bigger turbine housing
free-flowing headers
free flowing exhaust
ball-bearing center section
higher rpm powerband
P&P'd heads

basically, anything that will increase exhaust flow or if the car is built for higher rpm powerband usage, meaning the powerband starts at 4500 or higher.

[oil pan 4]

Arctc Wolf said it all, just about.
You could port and polish up the inside of the torus and compressor housing. That would just let the air/exhaust flow more freely through the turbo.
If you want a low rpm range keep the stock cam.

[OutKlast]

I wanted to do twin VNT's, where did you find them? Custom turbos are so much work, cars in general are so much work. :(

[Turbo V6 Camaro]

well my cam when running NA really really WAKES UP AT 4500 :eek: i mean like right now lol

[T-Punk]

you have to wait around ebay for unused ones but they come up. I think they will work out quite nicely since they are pretty small and will make boost almost instantly. i cant wait to see the power band when im done.

originally i was planning on bolting up to the stock tubular manifolds but now im thinking it would be easier to get some pacesetters and alter them and the y-pipe. I'm also thinking about waiting to start putting peices together and getting the tubular k-member. other than that im using a cartech FMU, probably a bosch BOV, Walbro 255, two k&n cone filters, and im going to try to get the IC and maybe the after IC piping from tiago. Then i gotta get an HP-Progammer and get to the hard work ;)

[ October 21, 2004, 12:28 AM: Message edited by: T-Punk ]