Realizing this is an open ended question and can be subjective. I am curious as to what cam sizes start causing excessive loping, shaking, etc.

Am looking to add a cam/heads/headers, etc. and would like to achieve approx. ~450 at the wheel while keeping some street manners. Since I know nothing about cams (and I mean nothing) thought I would toss it out to the experts.

 

One man's "excessive loping and shaking" is another man's "music and delight". I don't think your question can be properly answered here.

I've seen cars that would barely idle at all, ridiculous amount of "lope", in my opinion WAY too much cam for street use... yet the owners proclaim that the cam is NOT too big... ... it's VERY subjective. You could be easily misguided.

Your best bet would be to try to meet up with some C6 owners that have different cams and maybe have them take you for a short part-throttle low rpm ride around the block... or maybe they'd even let you drive the car in a parking lot or something. Point is, you should try to experience the cams for yourself if you can.

My personal advise would be, since you are going to get a wide range of answers and opinions here, when in doubt, be conservative. Don't worry about trying to obtain a specific HP level... be more concerned about making sure your car is fun and pleasurable to drive when your done modding it... because if the thing shakes, lopes, bucks etc so bad that it annoys the heck out of you every time you take it out, you're gonna be really unhappy... regardless of the HP gains.

 

This big:

(_______________________________________ ___________________)

 

A 224/228 xer cam is near zero lope and has zero drivability issues. With etp or afr heads it is 460rwhp.

 

What do you want your car to do? I think that is the first question to ask.

 

So true.

 

OK maybe I can offer my side as comparison since I'm still thinking about the cam.

I come from the import world and what constitutes streetable keeps moving towards the wild side.

A 'mild' cam (264/264) is one where at stock idle you will ALMOST die sometimes from a stop, but not nearly - good clutch control still allows you to bog a bit and go.

A medium cam (272/272) is where at stock idle you can get caught off guard and the engine dies. Usually raise idle to 1300-1500.

An extreme street cam, that used to be race but people start to run them on the street now would be 280/280 - like crap below 2k, idle gets raised significantly. PITA but when you're making serious 600whp with a 4 cylinder, your car's already pretty obnoxious and a 2500 idle hell that doesn't add all that much to the PITA factor...


So in light of this, what's the cutoffs for cams in the vette world?

 

Import? and what size engine??

now rember the corvette has a V8 and 5.7, 6 or 7 liters.

Those duration ot 264/264 and 272/272 are too long for a V8. One needs to not only look at the duration but lift as well.

Might be better to have a shorter duration and a higher lift. the Corvette loves low end torque from 2500 up to 4800 rpms then HP from 4600- up to 7000 rpms

LSx Cam Guide


I run a 228/228 570/570 on a 110 lsa with PP LS6 heads

 

One problem is that big cams has greater overlap which produce more unburned fuel at lower rpm:s. This makes deposit at pistons and combustion chambers and create missfirings. Todays engines that has injections is possible to program to deal with this (to a certain degree). Then cost for programming must be taken in to the picture especially with a very big cam. Myself I got a what we could call a BIG cam, 270 @050", (in my street car) and there IS carbon problems. I think 265 is the "big cam limit" for a street engine using injection. So, it is not just a question about beeing able to withstand living with a "rough idle", fouled pluggs dosent make anyone happy. I guess that a 235 @ 050, is something about the hottest for those not used to big cams.
Goran Malmberg

 

im assuming this is evo experience lol ... I had 264/264s and the car never died on me... basically like stock but would sometimes get lopey.. had some 280 piper rally cams in friends car and that thing sounded insane! I would like something like the 264s but one that doesnt give itself away to the dealer so easily.. everyone knew something was up with the evo and it makes my bullets seem really mellow.

 

I think he's referring to "total" duration as opposed to duration at .050" lift... and a "total" duration of 260-270-ish should be fine for a 6.0 liter, generally speaking. But I personally prefer to just stick with measurements at .050" lift when comparing.

True, but I think a common mistake is to run TOO high a lift for the application. If the heads etc can't handle the flow that the big lift can provide, then the high lift is a waste and will only serve to wear valvetrain parts excessively fast... which means breaking valve springs for nothing, etc. You ideally want to MATCH the parts... the lift should only be as high as the rest of the system can flow. Now you'll have to go to the experts to get the details on this.

Yes, lobe separation (and thus overlap) are also an important thing to look at. Tighter lobe separation (like 110 LSA or less) means more overlap per duration, and means more lope, shake, and general rough quirky operation at lower rpms. I happen to like wider lobe separations (minimal overlap) for street use (like a 114 LSA, etc)... personal preference... maybe less peak HP but more stable lower rpm behavior. All depends on your priorities.

But let the C6 experts guide you... each and every situation seems to have its own winning combo. You just need to find an expert that understands the true requirements of a daily driver as opposed to an all-out drag car so they can suggest a good user-friendly combo that you can live with.

I've swapped lots of cams and heads in my day, tested, experimented, etc... but that was a full 20 years ago...

 

He did say...

 

Holy cr*p!!!! Don Garlits must be jealous. How do you even drive that thing??? Must take a lot of patience and a lot of talent!



I might agree with this... very generally speaking... except I might go a tad lower on that figure just for the sake of being conservative. I've had 230 cams in 7.5 liter engines that I felt were right on the line of acceptability for street... being conservative. In a 6.0 liter engine such cams would act even bigger... but then again I was dealing with old carbureted engines back then, the modern fuel injected systems with the ability to fine tune via computers should help even the score I'd think.

Hey... just curious... anyone have the cam specs for the STOCK 7.0 liter Z06 LS7? Would be interesting to compare this cam to the factory cams used in 7.0 - 7.5 liter engines back in the old days.

For whatever it's worth... maybe not too much ... my favorite cam for my Pontiac 455 (7.5 liter) STREET car was a 222/236, 114 LSA... (right between a factory "455 H.O." cam and a factory Ram Air III / Super Duty cam)... a tiny bit of lope and twitch at idle only, but otherwise relatively smooth and very strong right off idle... ridiculous torque from 1,200 and up... super low emissions (as tested), excellent MPG, excellent manifold vacuum, no stalling or bitching on cold damp days, no hot start issues, no plug fouling, etc ... THAT'S the type of operation you want for STREET use... in my book anyway. Anything less "user-friendly" than that is a "race car" IMO. If you need to go faster on the street, just get a motorcycle.

 

211/230 591/591 120 LSA 1.8 rockers

 

I speced out my existing 06 Z06 cam, putting all parameters of the L7 into my Engine Analyzer program. So far it estimates stock performance and mods I have done (less 15% drive train loss) to within 10 HP, and the curves approximate the dyno.

If I advance this cam, which appears to be -3.3 degrees retarded, built in, to 10 degrees advance, the torque curve shifts up and to the left, while the peak HP increases 60 HP. Very tempting.

Thus I am considering advancing my cam. Any experience or thoughts would be seriously considered. Thanks.

 

Well, the word streetcar might be missleading a bit, I use the car for testing out my new geometry ideas and stuff like that. The thing is that the motor run pretty well with an injection system despite the big cam. It is just that the carbone ppm numbers get high during idle 800 rpm, but good at 2000 rpm. It is not even a Corvette, so I souldnt talk to much about it, but you may check my site . The motor is a 9 litre Hemi hence my name "Hemipanter".
Goran Malmberg

 

Thanks! My initial impression.... wow, pretty big difference between the intake and exhaust duration. Ridiculous amount of lift: .591" with 1.8 rockers, gee, didn't even think that was possible, those springs must work mighty hard!... I thought the .491" w/1.65 rockers on my 455 was bad, and it redlined only at 5,200 rpm... and I broke 2 valve springs too! 120 LSA, quite wide! I need to plot the overlap... I think I still have my "cam specs calculator" that I wrote in BASIC back on my 286 computer with DOS operating system. I wonder what the ground-in / installed advance is?

Very interesting cam specs, at least per what I am familiar with... things have changed a lot since the "musclecar" days.

Very interesting. Thanks for the installed position spec... do you mean 3.3 degrees retarded? Are you talking cam degrees or crank degrees? I will assume crank degrees, but... I've learned to always ask... have gotten bitten a few times by just assuming. I agree that merely changing cam position can help fine tune the torque curve nicely... and it's a lot easier than swapping the entire cam.

WOW, cool!!! Intense!

 

Am glad that I opened this post up b/c have learned a great deal about what I think might be "right" for my particular application via others opinions/experience. Will post back with what the shop and I decide upon

AU N EGL - Thanks for the cam guide

 

many of us do too. That is why so many ppl jump on the age old question, "Which Cam?" We all learn and share info.




Then we go to the track and

 

: and where might one get a program like this???