J-Rod

Think about this cam from TR or something similar...

99-230/224-111 Thunder Racing Custom "Reverse Split" Camshaft - 230/224 .575/.563 111 LSA 2200-6800 RPM Power Band. Excellent mid-range & high RPM power. Automatic cars require computer tuning and it is recommend for optimum results on manual transmission cars . Due to the fast ramp rate of this camshaft, the use of 1.8 rockers is not recommended.

Lucian

iTrader: (1)

thanks j-rod, I will check this out

jrp

iTrader: (16)

go with the tr224 112+4, you stated you dont want to rev high and thats what the 230 does.

Colonel

"Would it be better for drivability vs power to have less duration and a tighter LSA than more duration / wider LSA for a N/A setup? eg: a 234/232 106LSA with XE-R lobes vs a larger 238/240 112LSA."

The second cam would idle much better. If you made the LSA of the second cam 109.5 instead of 112 then they would idle very similarly.

I believe that Nineball, way back in '01, meant that increasing the lift (assuming the heads can support the added lift) will increase power all the way across the graph. It'll add power at all RPMs. I DO NOT think he meant that it will have a significant effect on where peak power is made. He did NOT mean that it will have an effect of the power curve such as is seen when increasing intake duration.

"Increasing lift moves the entire power curve upwards" (Upward as in on the HP axis, NOT the RPM axis.)

About LSA...

I do agree with J-rod that it should be viewed more as a resulting factor than an adjustable one in and of itself. However, I don't want anyone to misunderstand this. IMO, sometimes it's OK to change the LSA of a given cam but we should understand the effect that this will have before doing so. Of course, if we change the LSA, then we don't actually have the same cam anymore. Lemme give an example...

Let's say that I'm looking for a good street/strip cam and I narrow it down to a certain cam that makes peak power at 6000 and has an LSA of 112. Now, let's say that this cam seems to meet many, but not all, of my needs....it has an idle that is too rough for me. Let's also say this cam, in my setup, would need to be shifted at 6400 for best ETs....but I'm NOT looking to shift that low! I want the thing to turn at least 6800. Why? Maybe it's my gearing. Maybe I just loooooooove to hear an engine wind up. Whatever...point is, I want it to carry the power out higher. Ok, I can change a few different things to accomplish this. The most obvous thing to help it make power up high would be to increase the intake duration....but wait, this cam is already a little rough on the idle for my needs. NOT an option for me! Hmmm....well, I could retard the timing advance. That would help a little but I don't think it would help enough and I don't want to kill any power AT ALL just off idle because I do a good bit of parking lot driving you know. What's left? The LSA. I can widen the LSA to 115. That will smooth the idle out, it'll help power and smoothness at parking lot RPMs, it'll raise my peak power to 6200, and it'll carry the power out farther so that I can shift at 6800.

In other cases I would say that if you're looking to raise your shift RPM by widening the LSA then your cam is too small to begin with. But then there are cases like these. This was a similar case to mine when I designed the Stealth II cam. I wanted to shift at ~6700, I didn't care about a midrange power loss since I planned to run a 4000 stall and would never see this range at WOT, and above all else I wanted to have a silky smooth stock sounding idle. The cam accomplished all of this perfectly. I could have gotten the same idle from a smaller duration cam but I wouldn't have been able to turn the RPMs that I was looking for (nor would I have made as much power.)

Now, in RACING, where power is the ONLY thing that matters, throw LSA considerations out the window! It is indeed only a result of the valve timing events.

D Rock

iTrader: (7)

Guys please correct me if i'm wrong, but I always thought that a 112 LSA cam will peak at a higher rpm and that a 114 LSA cam will peak a little lower but have a broader range of powerband.

Take for example the ASA cars, they run a 110 LSA because they have all of their power in the upper rpms for the track racing.

I know that a 114 LSA or higher will have a smoother idle than a low LSA, but with the smoother idle, you also get a broader powerband, but leave a little bit of power on the table.

Colonel

A 112 should peak just a smidge lower than a 114 and the power will fall off slightly quicker. It will make slightly better power before the HP peak, however. In this way, yes, it will give a slightly broader power range...it's just that more of that power will be before the HP and less of it afterwards. Make sense?

DenzSS

The real truth of the matter is camshafts are the brain of your engine. Unless you are a real professional, or an amateur with an engineering/physics background with an AMAZING amount of experience, you will never be able to correctly design a camshaft. You may be able to get a half-assed camshaft that functions, but it will never be very good.

What you need to know is the basics of camshaft function and design. You need to know enough to pick a good designer and notice BS when you have to. It is an incredibly specialized field.

If you really want to know more, you're going to have to find a mentor.

D Rock

iTrader: (7)

I understand now, thanks