VIIIrs

iTrader: (5)

I've been more than happy with my Kelford 272's, i havn't had any issues with knock, I had an
1d10t install mine. and i don't see how GSC S1's would make more power IMO. But i am no supertech like some of you guys and don't know nearly as much as you all. AND IT WAS SO

bostonhatcher

iTrader: (18)

Cam selection has everything to do with what your revving to and nothing to do with displacement, boost, torque, etc.

Head porting has everything to do with what cam selection has nothing to do with.

Roadrunr

iTrader: (24)

The displacement of an engine is part of the equation when choosing a camshaft. A radical cam in a small displacement will have a higher usable power band compared to a larger displacement. A larger engine will tolerate a more radical cam without effecting the bottom and middle rev range.
Don

GregGSC

iTrader: (44)

duration can easily effect the performance of an engine in relationship to the displacement.

bostonhatcher

iTrader: (18)

I agree but would it not be better to run a 272 cam with a ported head over a 280 cam with a stock port head? You'll have a more usuable power band.

A 280 cam with a stock head is less mass air flow rate for a longer period of time.

A 272 cam with a ported head is more mass air flow rate for a shorter period of time.

A 2.3 requires more velocity than more duration because the pistons speeds are greater than a 2.0.

Yes you can do more flow with more duration but you have to think about the fact that more duration adds more overlap and will hurt you unless you're revving to 10k+ rpms.

David Buschur

iTrader: (53)

The entire cam design process is over my head, I admit it. I spend a bunch of time on the dyno putting cams in, dyno'ing, tuning and then pulling them back out. That's how I find out what works in every case. On paper or theory I could personally care less.

No our cams do not have to be run with our springs. There are other spring choices that will also work, it's one of those testing things, why risk it and why not just buy the recommend springs/retainers?

bostonhatcher

iTrader: (18)

It's very clear from the dyno chart in the first post that the bf272 has more overlap than the kelford 272. Change in overlap shifts the powerband, that's it. It loses as much down low as much as it gains in the top end. A cam with less overlap will give the combustion chamber more time to heat soak, causing knock.

Back to 280 vs. 272

Imagine this scenario:

Your piston is at top dead center. Your intake manifold has 40 psi of pressure. It's ideal that when the intake valve opens, your cylinder has 40 psi of pressure by the time your piston is at bottom dead center.

In order for your intake manifold and your combustion chamber to have an equilibrium of pressure, your head has to make that transformation happen.

You can do this buy holding the valve open longer or by increasing the port size. More duration will affect your low end much more than an increased port size, while they will both gain significant top end.

ssteve

iTrader: (5)

I have always been very impressed with my kelford 272's, and my car has always been VERY strong for the mods it has had... With that said when I build the motor Ill be going to something bigger(and not considering the kelfords)

ryno529

Dave just curious what is the lift on your cams? If you don't want to answer i understand.

GregGSC

iTrader: (44)

This is way to generalized to answer correctly. total duration is but a small piece of the puzzle. I'm not saying you are totally wrong i'm just saying there is much more to the puzzle. In relationship to a 2.3 vs a 2.0 and what you should change in the cam profile is simple you would want to run a longer 1mm duration on the 2.3.

crcain

When AMS tested the Kelfords, how many cam degrees did they need to set to get them to be at the right lobe centerlines?

JohnBradley

iTrader: (30)

Interesting findings on cams and incorrect dowel location. I finally got around to testing a "weird cam" car to see where the base timing was and it was definitely off. It gets fixed with a cam change so the only thing I can think of is the dowel. This car was off 5* crank when I checked it and the map really seems to show it.

https://www.evolutionm.net/forums/ec...or-timing.html

CR- dont know if they published that or not? I could probably tell you based on the cam engineering though. I would have to look at them but I have other cam specs I need to run in the sim first.

VIIIrs

iTrader: (5)

what kind of Cam was it that was "Weird" and by the way i like the fact that your looking more into it. Instead of just giving up on **** and saying it's junk.

crcain

When I timed a set of Revolvers they were 11.5 degrees off at the cam! It was the intake cam and my buddies car always ran great when he had those Revolvers. He ran 11.0 very easily with a Green and those Revolvers.

I also degreed some HKS 272's and they were right on the money.

JohnBradley

iTrader: (30)

That was a stock cam. Stock 2003 (4 so far) and 2005 (11-12) seem to occasionally pop up with incorrectly machined cams, no 2004s to date have had this problem on stock cams. I have only seen one example of aftermarket cams do this and I am not sure if it was the set or the brand. It went the other way though and I had to pull 5* of timing and richen the fuel map.

They arent junk, they still make stock cam power, but I am glad to help. We are the only group to document and claim its a problem. They are so few and far between I usually just tune it and leave it until we do cams. This one I HAD to see what the base timing difference was and if it was the cause. In my opinion I would have to say that ignition is based on something other than crank position in the Evolutions (probably the 2G eclipse/talon/etc.)

Having seen it on the one set of aftermarket cams, I would bet that this is more common than not. I have been told it depends on the machine used to grind the cams and how it "grabs" the cam...or chucks it up might be more accurate. If you saw it on some cams then it begins to show I am not the only one. The one thing I am wondering is how it affected your timing map and if it was more an actual engineering problem or dowel location issue?

Aaron