Would some of you cam experts give me some education on the different characteristics of cams with different LSA's?

I know that a narrower LSA cam will not idle as smooth as the same cam with a larger LSA, but what are the pros and cons on the powerband?

I am thinking of getting a Kartech Torquer cam with an LSA of only 110 for my C6 Z06 but am concerned about the power band. I am not looking for peak numbers, just really good power in normal daily driving range 2,000-6,000.

Thanks,
James

 

http://www.youtube.com/watch?v=Po_v8-TLnA8

 

Yeah, I already saw that video - it sounds great. Aside from sound and emissions, I want to know what LSA would be better for mid-range power. From what little I know, a smaller LSA number equals a narrower powerband, or more focused power?

 

I would recommend calling LAPD in Chatsworth and ask for Al, the shop manager. He is their cam specialist and will give info without obligation.
877 843-5273

Some light reading - second half of the article: http://www.popularhotrodding.com/eng...ion_angle.html
Nice chart at the bottom.

BJK

 

A lot depends on how you plan to use your car. Is this a daily driver, a weekend warrior, or a full tilt race car? Also, what other mods do you have, or are you already considering? What are the other specs on the Katech cam that you are considering?

If this is a daily driver, a 110 LSA is way too tight, IMHO. One of the beauties of the LSx engines is the combination of smooth driving manners, and instant power on demand. The 110 LSA will idle very roughly, will require that you bump up the idle speed, and will require ECM tuning to maintain crisp throttle response and driveability. Your gas mileage will suffer, and you may not be able to pass an emissions test.

If this is a weekend warrior, a 112 LSA will still give you a nice lopey idle, and you'll still have decent street manners. You will probably still need computer tuning, and may have to bump up the idle.

If this is a full tilt race car, then the sky is the limit, especially if you don't plan to drive it on the street.

While the chart that is referenced in the PHR article is generally accurate, it varies from engine to engine. Typically very tight LSA's work best on engines with very large duration cams. Once the duration gets over 230 degrees, it's difficult to use a wide LSA.

You might be surprised to see how little impact the LSA will have on your peak power --- often only 5 HP or so. Also, what you gain in the mid-range, you often lose at higher RPMs.

Best advice is to talk to a reputable tuner, give him a complete description of your driving style, mods, and performance goals, then take his advice.

 

I agree with everything you said except the highlighted part. Very wide LSAs work best on engines with large duration cams. You don't see many cams over about 270 degrees duration (@.050") with 108 degrees LSA. As they progress on up to 290 degrees duration, LSA goes to 118 degrees. It's difficult to use tight LSAs with very large duration cams because the overlap increases to the point that intake dilution prevents the engine from getting a sufficient charge of fresh air/fuel to sustain any kind of idle. Check out this list of cams from Comp Cams:
http://www.compcams.com/technical/Ca...01_227-228.pdf
Scroll down about three-fourths of the way to the mechanical roller drag race cams to get to the very large duration cams and look at what happens to their LSAs.

 

I've used 114 LSA's in my LS1 & LS2 motors, with durations Ranging from the low 220's to the high 220's. With the proper tune they worked very well and had very good idle quality. At present I'm running a cam in my 427 with a 232/234 duration on a slightly tighter LSA of 112. This 112 LSA increased my midrange greatly, and since this is a street daily driver that's just what I wanted. I will say, I was concerned about Idle quality, but with the added cubic inches and a speed density tune; it ildes great with slight lope at 900 rpms. I would say choose your cam around what the car is going to be used for. You'll be much happier in the long run.

 

I want to thank all of you for your input - good info .

James

 

Agreed. If i wanted a sleeper grind i would use a nice 115-116LSA. Daily driver with some cam grunt 112-114LSA. Duration plays a part as well

 

Dr. Slipper, I presume? I do so enjoy our intellectual discourses! As usual, you are correct in your basic premise, but I happen to disagree with your conclusion. What is true for Pro Stock type roller tappet cams doesn't always apply to hydraulic cams for LSx engines.

Let's start with what we do agree on:

. Bigger duration cams will have more overlap than smaller duration cams, even if both are on the same LSA.
. A tighter LSA increases overlap
. Long overlap periods work best for high-rpm power. For the street, a long overlap period combined with long-duration profiles combine to kill low-speed torque.
. Reducing overlap on a long-duration cam will increase midrange torque at the expense of peak power. If the average TQ improves in your desired power band, that's a good tradeoff.

Hope you agree so far.

As a practical matter, there are very few tuners who offer cams for the LSx with durations over 230 degrees, and wide LSA's. This is especially true for cams offered for LS1 and LS6 engines, less true for the larger displacement LS2, LS3, and LS7 engines. The greater displacement offers more baseline TQ to work with, and gives the tuner more latitude.

Let's take a few real-world examples.

GM offers several OEM cams for the LSx engines, all with LSA of 116 or higher. The new LS7 cam's LSA is 120 I believe, with intake duration at 215, and exhaust duration at 230.

However GM also offers a couple of high-po cams of longer duration. One is the ASA cam, with duration at 226/236, and an LSA of 110. The tighter LSA keeps the powerband from 2500 to 6500 RPMs. No spinning this hydraulic cam to 9K RPMS, as you can do with a solid roller cam.

Another long duration cam offered by GM is the GrandAm cam, with duration at 239/251, and an LSA of 106 (!!). The powerband of this cam is shown as 4000 to 7000 RPMs. This is about the upper limit of the RPM range for hydraulic cams.

Let's take another popular cam, the famous TREX from Thunder Racing. Duration is 242/248 on a 110 LSA. Powerband is shown in their catalog as 3500 to 6700 RPMs.

I looked at over 80 aftermarket cam specs for the LSx, from the following vendors: GM, CC, Lunati, Crane, Futral, MTI, SLP, Thunder, and Texas Speed. There were not that many with duration at 230 degrees or higher, and NONE of those had an LSA higher than 114. There were a half-dozen or so cams with LSA's wider than 114 (not counting the many GM OEM offerings). Almost all of them had duration under 220 degrees. Two notable exceptions were the Stealth cams offered by MTI, one at 220/220 on a 115 LSA, the other at 224/220 on a 116 LSA.

And yes, I did look at the 3 "XFI" solid roller cams for the LSx offered by Comp Cams. The durations listed were 235/240, 243/248, and 251/256. LSA for all 3 cams was 113.

To summarize, the vast majority of aftermarket cams offered for our LSx engines have LSA's between 112 and 114. The milder grinds with shorter intake duration (210-220) often have wider LSA's, up to 116-117. The bigger cams with lots of intake duration (230+) usually have LSA's under 114, going down to as low as 206-210.

Not an opinion, just what my research has found.

As usual, fun jousting with you!

 

See my sig, the 113 LSA for me has a very nice lope

Remember to choose a CAM for an upgrade path, meaning NOS, FI etc, its no good to have to do it over.

 

If you want unbeliveable torque from 3000-6000 you will love the Torquer LS7 cam. Major torque increases 3200-4500rpm over the stock cam. It idles with a moderate lope at 975rpm. I have the Torquer cam in my Z06 that I drive daily in the summer. I sit in traffic with it, I've traveled on road trips with it, and I've road raced it. I've driven 6500 miles since the install and I'm still loving it.

 

Katech, thanks for chimming in. What if I wanted unbelivable torque starting at 2,000 rpms, do you have a different cam for that? Why did you chose an LSA of only 110?

Also, do you have a dyno chart for the torquer cam versus a stock cam and maybe an unnamed competitors cam? I would like to see if there is any loss down low.

I guess I am getting older because I do not want to spin the hell out of my car to get into the sweet spot. I will probably not take my car past 5,500-6,000 rpms very often. I hear your statement that you daily drive it, but you do not say it is the best choice for daily driving. I am looking for a cam like LG's headers - they do not have the best peak numbers, but are the best for midrange power.

Thanks for your help!
James

 

Yes Professor HITMAN, it's me...and it's been a while since we've had a good cam discussion.

And yes, I agree with everything you've said in your post. As usual, a difference in perspective has created what seemed like a difference in opinion. I thought you were talking in general terms (you even used the word "general" in that paragraph in your first post), not specifically about LSx engines and hydraulic roller cams. You are absolutely correct that what applies to Pro Stock solid roller cams will never apply to LSx hydraulic roller cams. The Pro Stock engines are 500 CU IN and turn 10,000 RPM, and while the LSx engine can be taken to 511 CU IN, that size LSx will never see 10,000 RPM because of the limitations of valve size...the 4.4" bore spacing will not allow a valve of sufficient diameter to sustain that RPM with power. The momentum of the charge flowing through the huge intake ports/valves of a Pro Stock engine at 10,000 RPM can use the very late closing of the intake valve (due to the very long duration and wide LSA) to "supercharge" the cylinder and make substantial amounts of power. The proverbial "apples and oranges" comparison.

Compared to the LS7 120 degrees LSA, an LSA of 110 degrees is a tighter LSA...relatively speaking. However, in the high performance world, anything over 110 degrees is considered a wide LSA and anything less is considered a tight LSA...in general. So a lot of the cams you found are still considered to have wide LSAs...in general. But relative to the stock cams, they have tighter LSAs...again, just a difference in perspective. I think the formula you came up with to compare cams using the LSA and intake duration to get an idea of how an aftermarket cam's drivability will be relative to the stock cam (or when comparing any two cams) is the best tool I've seen. It might be worth repeating for the OP, newbies, and as a reminder to others.

80 cams and 9 vendors!!! That was a lot of research! Good job as usual.

 

I am old(er)...in in my younger days I used to run a Comp Cams 292h in a first generation small block I drove on the steet. I believe the LSA was about 110. You could charge admission to listen to it idle(too cool) but street manners were another thing. I am very interested in the so called stealth cams such as the Thunder Racing Cheatr and the LPE GT11...where is their power band? ...of particular importance to me is the fact that to do my daily drive I spend a great deal of time in 5th and 6th gears between 1200-2000rpm and do not want any surging/bad manners in this range if it can be helped. Right now I have a bone stock 2005 mn6 but am considering H/C versus giving in to a Paxton blower ...maybe TJ WONG could chime in as I hear he is a big fan of the GT11...thanks