show me your dyno charts

[oi138]

My FSM makes no distinction between S13 and S14 cams...I have PDM-Racing stage 2 S14 cams, better than both S13 AND nissan motorsports cams! I don't mean to be antagonistic, I'm just wondering why Nissan did that...!

Why did nissan put a smaller turbo on later model z31's?Why did nissan make the 96 model z32 20 hp less?Why did nissan make s14 cams worse than s13 cams?

No one really knows. But all of this is true. sad. but true.

And to those of us who run a lot of boost. pdm cams will not work. It has been confirmed on dyno charts that 2 s13 exhaust cams make more power on turbocharged cars.

[MarkEmark]

"And to those of us who run a lot of boost," ie, NOT me, only people like you who DON'T have PDM cams...as I said earlier, im going no more than 7 psi, starting at 5 psi...Don has said they work fine with this boost...and I think he knows a thing or two about boosting/building cars...And the cams will never NOT work (unless under extreme boosting), they'll just decrease performance. If you read the factory specs versus the PDM specs, they are NOT drastic changes made in the cam grinding whatsoever...in fact, your s13 intake/exhaust cams have longer duration than my S14 reground cams if I'm correct...turbo's don't like long duration...But enough about this camshaft nonsense...I assure you my 7 psi turbocharged 240 will give me more than enough power to play around with, and as long as I'm happy, and as long as you're happy, that's all that matters, right? Happy friday night everyone

[oi138]

whoa there don't take offense to what i said. I have nothing against pdm cams. I was gonna get some til i decided to go turbo. And yes I did read that you were only gonna run 7 psi that's why i said to those of us that run a lot of boost. Sorry that i came off as an ***. But I'm probably gonna come off as an *** hear too.Try not to take offense to this. It's just a pet peeve of mine but in your signature you have hotshot headers listed. But we don't have a banked motor my friend therefore we only have one header. so please remove the "s". Again don't take offense. Just trying to educate you. And yes 7 psi made me happy. But once you feel more it will make you sad.

[MarkEmark]

Lordy, oi138, I didn't know this would deteriorate into a game of semantics...I guess I say hotshot headers because everyone else, including enjuku racing calls them hotshot headers as well...right on Enjuku's main page it says "hotshot headers, $329, free shipping!" It just sounds weird to say header, i guess I was thinking each individual pipe going to each cylinder was a "header." I guess I'll be even more correct and call it "hot shot exhaust manifold"But anyway, you win, check my sig :rolleyes

[oi138]

lolthanks.

[WDRacing]

Just for the record, forced induction motors seem to like longer duration, The duration should be increased with boost and rpm, I ran 248's in my RB20, stock being 240. I noticed an immediate pull throughout the entire rev range...

I like a longer duration as opposed to a longer lift cycle...lets say you get silly with duration, say anything over 256, then your power band is going to come on later in the rpm range, so if your running a larger turbine, or have raised your rev limiter, you'll benefit from a longer duration cam.

Any cams under 256 will be fine with low or high boost.

Its a good thread, lets keep the info coming...

WD

[cow]

Well, I have always been under the impression, based on both technical writings and hearsay (heh) that a SHORT duration, high lift cam is best for forced induction. This is because a long duration cam produces overlap which in turn tends to create boost blowby; that is, the valves are open too long for a lot of boost to be crammed into the CC. Thoughts?

[MarkEmark]

Okay, so my cams will be fine for my 7psi low boost application, even efficacious for horsepower over stock ones, I dare venture......they're higher lift than stock, and not that much more of duration...LORD I can't wait for boost!

[oi138]

...I guess I say hotshot headers because everyone else, including enjuku racing calls them hotshot headers as well...right on Enjuku's main page it says "hotshot headers, $329, free shipping!"

http://w1.igateway.com/clients...issan 240sx&Department=headersClick here and goto page 13.Now you know I had to call you out on that one. lolno please don't hurt me. j/k

[king_johnthegreat]

A long duration cam allows "Back-flow" of boost pressure out of the combustion chamber because it leaves the valve open for a greater period of time. The charge air wants to rush into the valve as it opens, but once it reaches significant pressure, if the valve remains open, it can expand its way back out. Power comes from having that air inside the cylinder, and keeping it there; but the only way to do so while reducing the negative effect of back-flow is to open the valve as wide as possible. That way, you can flow the same volume of air as a long duration cam; but do so quicker, thusly trapping all that great pressure and fuel inside the combustion chamber. By having the valves close quicker, and be further apart, the timing can also be kept advanced with less risk of firing through the manifold in a detonation scenario. This means less damage to the throttle plate, turbo, etc.,. It is rare to detonate with a valve open, or even partial; but stranger things have happened. Simply take into consideration the physics of the motor, and the fact that a piston acts as a pump. It is on a down stroke during intake, so yes, it does help to keep the air in the cylinder with any duration; but the cylinder is hot, and fuel is expanding every bit as much as the air. This occurs FAR more with forced induction than natural aspiration, so duration CAN be looked as a neg. aspect of a cam profile for turbo cars. There are reasons to go either way, and my knowledge is by no means an end all. I speak from my experience with growing up in a family of professional race car builders and drivers.John