HITMAN99

Vet, I respect your opinion, but you're just dead flat wrong on a couple of points.

First, you say that you kept the lobe separation relatively tight for minimal overlap and minimal lope. In reality, it is exactly the opposite --- the tighter the lobe separation, the more overlap and lope. The stock LSx cams have 116-117 LSA, while most aftermarket performance cams have 112-114 LSA.

Second, a performance cam does move the power band up, but much less than you might think. Typical peak TQ on an LSx engine occurs right around 4400 RPMs. Typical peak TQ on the same engine with a larger cam (let's say 20 degrees more duration) will occur around 4600 RPMs. True, SOME really big cams with 240+ duration will move the power band even higher, but not too many guys are running those cams in their daily drivers.

Third, there are MANY cams that will give you a nice all-around power boost without affecting low RPM operation much at all. I ran a 218/224 114 LSA cam in my Camaro for several years. It was almost impossible to detect it at idle (and I had lots of guys stand there and try), my gas mileage was completely unaffected (23 MPG), it passed very strict VA emissions testing (on the rollers with a tailpipe sniffer) with ease, and driveability was excellent. From a dead stop, I could easily get the car rolling just by letting out the clutch, with no gas, and it would effortlessly roll around inside parking garages with just the slightest pressure on the gas pedal. Idle RPMs were same as stock. Yet, from a roll in second gear I could easily break the tires loose just by rolling on the gas. I got 383 HP/TQ through shorty headers, OEM cats and catback.

LSx engines are NOT your father's big block muscle car! DON'T be afraid of a mid-size cam for a daily driver. There are many very fine "stealth" cams that will give you good power and great street manners.

glennhl

I'll back up Hitmann. I ran a 224/224 .581/.581 112 LSA in my Camaro and it was very docile on the street. The 112 gave it a little lope at idle, but you didn't notice it unless the cutout was open.

Zig

i'll have to read it again, but, that's what i thought he was talking about.. REALLY BIG CAMS.

Big Power, Big Cam, higher redline, etc.
docile cam, relative power gains, simliar to stock redline, etc. etc.

daily drivers and race cars are two different animals.

Vet

Yes, I agree with you. I made a careless error when I said "tight"... I meant "wide". It's been a while... I'm fumbling my terminology . I remember, one cam I had tried in my old Pontiac was a 230/237 with a "tight" 110 lobe separation... terrible for street use, twitchy and weak down low... then went back to a 222/234 with a "wide" 114 LSA , slightly advanced... was WAY better... etc... but it was a 462 cubic inch engine. While the 222/234 was good in the 462, it may have been a tad big for a smaller engine such as a 350, but I never worked with "tiny" engines like 350s .

Ok, this makes good sense. I'd indeed agree that a cam with 240 duration in an LS2 would be "too big" for daily driver street use... (well, to me, 230-240 on the intake is too big)... so, looks like we may be close to being on the same page after all. I guess I never defined what I'd consider to be a "big" cam. I can tell you that, at least in my carbureted 462, anything with an intake duration of about 230 or bigger and LSA of less than 112 - 110, in my opinion, just did not behave in an acceptable manner for daily driver street use, even in a 462. (The definition of "acceptable" will vary of course... I am conservative... for every day use, traffic, etc, I do not want ANY headaches whatsoever.)

Yes, the 462 made enough low-end torque even with a "big" cam, but down low it was still twitchy, not crisp, you could smell the unburned fuel leaving the tailpipes, spitty sloppy operation until the revs came up ... so I'm driving to the supermarket like this ... far from optimum for the intended use. A different story for strip use of course.

Again, we may not be too far off the same page since I would look at a 218/224 - 114 LSA as a good "high performance street" cam. Engine size does matter here of course... I will assume you are talking about a 350 in your Camaro. Still, I'd think, just from general experience, that a 218/224 would be cool in a 350. Perhaps it would act similar to the way my 222/234 acted in my 462... which I felt was only a tad "racey", and very streetable... this was the cam I wound up leaving in the engine after all my tests.

When I responded to the original poster in this thread, I guess I was thinking that if he was going to go through the trouble / expense of swapping a cam in a C6 (which is ultimately going to be more challenging to deal with than a 1973 Camaro or Trans Am etc), that he'd be shooting for a big noticeable horsepower boost and a cool sounding "lopey idle" (meaning BIG cam, like 230+). THAT I felt deserved a fair warning, especially since he said the car is a daily driver. (Note - at that time I did not notice his FIRST post about the 218/218, only saw the later post - sorry )

It sounded like he may not have been keen on taking a chance on a cam swap project if it wasn't going to give him a high yield... and I have to question how much of a yield one would get by going up only a small step in cam size. Maybe he'd be better off with just a tune. (?) Might be more cost effective for STREET use. (?) So, that's really where I was coming from. You guys would know better concerning the LS2 / C6 specifically of course.

Plus, as I mentioned in my last post, back when I was doing cam swaps and tests, I was dealing with carbureted engines and no onboard computers. I'd think that anything with fuel injection and the ability to tune easily and precisely via the onboard computer will ultimately yield better overall street manners than anything with an old Q-jet etc... so, this may be why I tend to think in more conservative terms regarding cams than the modern generation of hot rodders.

I guess over the years I've just seen too many kids throw in giant cams and basically ruin their cars... they get sold on the idea that a big cam is all about "gain" and are blind to the potential related "losses". So now and then I feel compelled to at least "alert" and/or "warn" people about the perils of getting too "cam-happy", at least for daily driver cars. At least my intentions are noble!



Ok, back to C6 General!

CYA-Vett

If you put in a large reverse split cam you can still gain on the low end over stock. Even standard split cams have very little loss down low.
It's time to find a few of my old dyno sheets...

cthusker

Dig em out.... love to see them...........

Zig

CYA-Vett

Ok cam #1 reverse split 230 228 (MTI X1)
This cam made both HP and Torque from idle to redline
2,000 RPM 20 ADDITIONAL Pounds of Torque (8 HP)
3,000 RPM 30 ADDITIONAL Pounds of Torque (10 HP)
3,500 RPM 30 ADDITIONAL HP and Torque


Cam #2 Standard Split 232 234 (Torquer 2 Texas Speed)
Here is your low end loss, but again, its is very slight, not to mention you can already roast the tires stock so adding more power off idle is counter productive...unless your on a race track, with heated up sticky tires.
In this graph I lose about 5 pound of Torque from 2,500 to 3,000 RPM, from there it just goes up. I would trade off 5 pounds that low for the 42 I gained at the top. There was never a low end HP loss, they were equal until 3,600 then the cam took over.


Now, it is obvious that driveability takes a hit here. Depending your tolerance. The Reverse split drove nicer and didn't surge like the standard split. Most people frown upon reverse split cams but I ran 11.3 with the car with only that cam. Standard split cams are better for racing, but based on my experience if you're not going to race your car the additional power down low with a reverse split cam is more fun on the street, plus driveability is better.

aero400

Thank you for the info!

You mention that the 232/234 takes a hit in driveability. That is pretty much in accordance with what Vet and others have generally said about cam size. So I will take it that durations of 230 and up are approaching the range that is not appropriate for daily use. I personally would not want any "surging" as you describe. I could not tolerate that in an everyday car.

You did not mention the lobe separation specs of the above cams. Please do. Lobe separation is a pretty important factor as it determines the amount of effective overlap per durations. Better yet (so that we don't have to do the math), do you have the effective overlap specs of the two above cams? Thanks.

You mentioned that the reverse split cams are more fun on the street. This is pretty much the opposite of what I have read in the past but not doubting it. But the amount of overlap may be what is making such reverse split cams either strong down low or not compared to other cams - maybe. Point being that we need to look at the amont of overlap of all these cams since the overlap may have more of an effect on lower range driveability (surging) than whether or not the grind is split or reverse split or not split. Just theorizing.

Also what about the installation position? I wonder what the ground in lobe angle position is on these cams. Secondly, where exactly did you degree them in at? Any advance, retard, straight up, or? I'd think this would have an effect on the end results, at least when comparing one cam to another.

Thank you for the info. Very interesting and informative. Great forum!

Zig

hehehehe..degree the cam..heheheh.. advance and retard...hehehehe

as long as you don't get too aggressive with the cam. will the ecm ajust and compensate. what are the effects when using the 'stock' program.

anyone the maximum 'profile' the ecm will handle ?

HITMAN99

Re the driveability, there is a fairly simple formula that will give you a good idea. Add the intake and exhaust duration together, divide by two to get the "average" duration. Then subtract the LSA multiplied by two. The more that the sum is negative, the more that driveability will be OK.

Let's take a few examples: one is the cam I had in my Camaro --- 218/224 on a 114 LSA. Average of the intake and exhaust duration is 221, 114 LSA X 2 is 228, result is -7. Equals very mild lope at idle, great driveability. Second example is 224/224 on a 11 LSA (Glennhl's cam). Average duration is 224, 112 LSA X 2 is 224, result is 0. Some lope at idle, decent driveability. Third example is the 232/234 on a 114 LSA. Average duration is 233, 114 LSA X2 is 228, result is +5. Significant lope at idle, marginal driveability. Today's tuning wizards can tame down such a cam, but only up to a point.

Advancing the cam a few degrees will move the TQ band down a little, also improve off-idle response, at the expense of high RPM power. You can use an adjustable timing chain setup to do this, but few guys bother with this approach, preferring to get the cam ground to their specs instead.

aero400

Makes sense. This formula appears to yield the overlap figure, at least when measured at .050" lift or whatever lift the durations are being measured at.

You mean +5. Five degrees of overlap at .050" lift.

I'd agree with this. You are basically saying: the more overlap, the less driveability.

HITMAN99

Yup, my bad --- I fixed it.

You are also correct that the durations quoted are at .050".

Zig, yes the ECM will adjust up to a point, but typically what happens is that the fuel trims get maxed out. Almost any cam, no matter how mild, will benefit from a tune. I know a few guys who have run a Z06 cam in an LS1 without too many problems, but I wouldn't want to do it myself.

CYA-Vett

Driveability for me was fine. I can tell you this, for the size of that cam it was a lot more driveable than some others I had. That is a good cam. It drives than the 228-232 114LSA cam I had.

By the way, the LSA on cam 1 was 112, cam 2 was 113.

I've been through 5 cams, the X1 was my favorite the Torquer 2 was #2 the G1 (228 232) was third, the rest were too small....

Zig

yes, agreed, but would you happen to know what the maximum profile is that would still be withing the tolerances of the stock tune.

yes, absolutely, i was just wondering what the max. the engineers built into the system.

was that a gm parts z06 cam, yr/etc. or an aftermarket z06 style profile ?

HITMAN99

That was an OEM stock GM cam. I have no idea how well the ECM can adapt to mild cam changes.

CYA-Vett

Very well. I would bet a mild 224 224 cam on a stock tune in an LS2 will be within 3-7 HP of a fully tuned car. It will go rich on the upper end. A larger cam maybe 5-12HP and a huge cam 10-20HP.

I may have a dyno chart on this....lemme look

glennhl

The 224/224 cam didn't want to idle in my LS1. I had to open the throttle blade slightly to get it to idle. Plus, when I got it tuned I picked up 14 hp. I would think a tune is a must for a 224 cam, even in an LS2.

CYA-Vett

With just adding a cam and nothing else?
My 232 234 idles and drove great without a tune. I already had headers and a tune.
Ahhhh, now I remember....I wasn't coming from a stock tune, maybe thats the difference

glennhl

That makes sense. I really liked the 224 cam, but I liked it a whole bunch more after the tune. However, I did have the cruise control affect even after the tune. I don't know if I ever got the throttle body adjusted back correctly.