Looking for alternative over HOT Cam, planning to bump compression to 11.1 by using Impala SS Head gasket, LT1 CNC heads flow 260 intake and 205 exhaust, should I go with duration or lift? The racier the idle the better without sacrificing too much low end grunt, don't mind revving to 6 or 6200 RPM.

Currently run 12.80s at 110 MPH on street tires naturally aspirated, stock short block.

Thanks,
JWheel
:steering:

 

I'd think one of the Comp Cams Extreme Energy grinds would work well.
You also need to take into account your exhaust, tranny, gears and/or converter, tunning, etc....

6,200 rpm isn't that high if you want "Max HP & Torque"

 

CC306 might be for you

 

As long as you have a stick! :iagree:

You might look into some of these grinds from GTP Racing:
http://gtp-racing.com/cam-lt1.htm

I have the GTP-2 in my car and it's a great cam for my stage 1 heads. Looks like they have some pretty aggressive grinds that might fit your needs...or maybe not!

 

To get the most out of the CC306, you will need to rev your engine alot higher than 6000/6200 rpms. If this is your intended rpm range, your hot cam should work just fine.

 

heres a rough guide to the duration required for max efficiency at differant rpm ranges


youll generally want to get the LSA in the 112-114 range, to work correctly with EFI, the duration in the minimum for the RPM ranges involved, anf the lifts to match your cylinder heads flow curve. if your intending to effectively let the engine breath at 6200rpm that will require at least a 225-230 duration, now Im not saying a cam with lower duration won,t spin 6200rpm, but it sure won,t make the same effective use of port flow or power as a cam of at least 225-230@.050 duration will, but keep in mind the DYNAMIC COMPRESSION RATIO should be in the 7.5-8.0 range for a street engine and the intake and exhaust length and dia. should also match the engines displacement and effective intended power range if your intent is max power production
but because this is a street driven car, a slightly milder duration like the http://dab7.cranecams.com/SpecCard/D...1=Display+Card
is a much better match because it keeps MORE of the useable TORQUR CURVE in the range of most corvettes gearing and makes for a far better manored street car
[b]read these lessons (#1-8)
http://www.newcovenant.com/speedcraf...camshaft/3.htm
The LSA, or lobe separation angle, is ground into the cam and cannot be changed. It is the angle that separates the intake and exhaust lobe for a particular cylinder, and is measured in camshaft degrees. The intake lobe centerline is measured in crankshaft degrees. The #1 intake lobe centerline is usually between 100° to 110° ATDC and is what you use to degree the cam. The cam manufacturer will publish the specs for the cam based on a given intake lobe centerline. Comp Cams, for instance, produces a large number of cams with 110*° LSA ground 4° advanced, so they list the specs for the cam with a 106° intake lobe centerline. You can calculate the ILC by adding the intake opening angle in °BTDC, the intake closing angle in °ABDC, plus 180° for the distance from TDC to BDC. Divide by 2 and subtract the intake opening angle and you will have the ILC. For example a 12-430-8 Comp Cam lists IO at 34°BTDC, IC at 66° ATDC, so 34 + 66 + 180 = 280. 280/2 = 140. 140 - 34 = 106° ILC
Figure 3 is a picture of both an intake and an exhaust lobe of a camshaft, seen end-on. It shows the relationship between the lobes, shows the overlap area, and illustrates this next section.
As stated in lesson 2, overlap has a great deal to do with overall engine performance. Small overlap makes low-end torque but less high-end power. Large overlap reduces low-end torque but increases high-end power.
Overlap is determined by two other cam specifications, Duration and Lobe Center Angle.
Duration is the time, measured in crankshaft degrees, that a valve is open. A duration of 204 degrees means that while the valve is open, the crankshaft rotates through 204 degrees.
Duration is measured on two "standards," "advertised duration" and "duration at 0.050"." Advertised duration is measured from when the valve just starts to lift off its seat to when it just touches the seat again. This is measured in different ways by different manufacturers. Some measure when the valve lifter is raised 0.004", some at 0.006", and some at different points yet. So the industry agreed to another standard that was supposed to make it easier to compare cams. In this standard, the duration is measured between the point where the lifter is raised by 0.050", and the point where it is lowered again to 0.050".
The 0.050" standard is great for side-by-side "catalog" comparisons between cams. But if you use engine prediction software on your computer, the software is much more accurate when you can feed it "advertised" duration numbers.
Lobe Center Angle is the distance in degrees between the centers of the lobes on the camshaft.
To increase duration, cam makers grind the lobes wider on the base circle of the cam. This makes the lobes overlap each other more, increasing overlap. More duration = more overlap.
To increase overlap without changing duration, cam makers will grind the lobes closer together, making a smaller lobe center angle. Less lobe center angle = more overlap.
Overlap and duration are the two big factors in cam design. More overlap moves the power band up in the engine's RPM range.
Longer duration keeps the valves open longer, so more air/fuel or exhaust can flow at higher speeds. It works out that increasing the duration of the camshaft by 10 degrees moves the engine's power band up by about 500 rpm.
A smaller lobe separation increases overlap, so a smaller lobe separation angle causes the engine's torque to peak early in the power band. Torque builds rapidly, peaks out, then falls off quickly. More lobe separation causes torque to build more slowly and peak later, but it is spread more evenly over the power band. So a larger lobe separation angle creates a flatter torque curve.
So you can see how a cam maker can tailor the camshaft specs to produce a particular power band in an engine--

Short duration with a wide separation angle might be best for towing, producing a strong, smooth low-end torque curve.
Long duration with a short separation angle might be suited for high-rpm drag racing, with a high-end, sharp torque peak.
Moderate duration with wide separation angle might be best suited for an all-around street performance engine, producing a longer, smoother torque band that can still breathe well at higher RPM.
Remember, there's always a compromise made in this process.

One last item to consider is the lobe centerline. The lobe centerline is the angle of the lobe's center peak, measured in crankshaft degrees when the piston is at Top Dead Center (TDC). In general (but not always), when a cam is installed "straight up," the intake lobe centerline and the lobe separation angle are the same.
The lobe centerline can be altered when the camshaft is installed, by advancing or retarding the camshaft's position in relation to the crankshaft. Advancing the camshaft by 4 degrees will move the power band about 200 RPM lower in the RPM band. Retarding the cam by 4 degrees will likewise move the power band 200 RPM higher in the RPM band. This allows you to fine-tune the engine's performance according to your needs.



if cams are a mystery please take the time to read these, it will get you a good start

http://www.newcovenant.com/speedcraf...camshaft/1.htm
(read LESSONs 1-8)

http://www.mercurycapri.com/technica...e/cam/lca.html

http://www.wighat.com/fcr3/confusion.htm

http://www.cranecams.com/instruction...in/camfail.htm

http://www.mercurycapri.com/technica...cam/index.html

http://www.idavette.net/hib/camcon.htm

http://www.cranecams.com/master/adjustvt.htm

http://www.centuryperformance.com/valveadjustment.htm

http://www.totalengineairflow.com/tech/valvelashing.htm

http://www.chevytalk.com/tech/engine/Cam_Selection.html

http://www.chevytalk.com/tech/101/Cam_Theory.html

http://www.babcox.com/editorial/ar/ar119736.htm

http://www.mercurycapri.com/technica...e/cam/vtg.html

http://www.n2performance.com/lecture1.shtml

http://www.symuli.com/vw/camp1.html

http://www.symuli.com/vw/camp2.html

http://home.wxs.nl/~meine119/tech/camqa.html
http://www.chevytalk.com/tech/101/Cam_Theory.html




[Modified by grumpyvette, 4:02 PM 6/23/2003]

 

:eek: :eek: :eek: :thumbs:

 

Thanks to all for the technical insight and real world advice. I decided to go with a custom grind from Comp Cams with specs of 230 / 236 and lift 510 / 520 and 112 LSA. Lift with 1.6 Rollers will be .544 / 554. Plan to run dual spring from Comp Cams, part #987, ordered from Summit Racing, excellent service.

I'll report back once I get it dialed in....... can't wait :D

 

hey grumpy vette you seem very knowledgable with cams, can you read my post from eariler today and give me a suggestion? Oh and i want to keep my stock computer and TPI set up. My ultimate goal is 11.99. i'm only .24 off of that, but i need it in the second half of the quarter

 

wheeljo2
I think youll find thats almost identical to the hydrolic roller cam I run in my stealth ram equiped 11:1 cpr 383
http://dab7.cranecams.com/SpecCard/D...1=Display+Card
its a little more than what would be ideal on the street but it will sure set you back in the seat once you pop the 150-200hp giggle gas :D :thumbs:

mike 1985
Id suggest the crane 114142, its as hot as the stock computer and torque converter will allow, its worth about 35hp-40hp more than the stock hydrolic flat tappet cam
youll need to run a chip to get the most out of it but it will run in the stock computer, it really likes a free flow exhaust and ported plenum and runners so keep that in mind also. (it loves giggle gas :thumbs: :thumbs:
http://dab7.cranecams.com/SpecCard/D...1=Display+Card


call and talk to CRANE
1-386-258-6174 Tech Line

btw its one of the cams I tested in my 383, youll like it!



[Modified by grumpyvette, 11:22 PM 6/23/2003]

 

Just a bit of info, the Hotcam peaks at 6500rpm (with stock LT4 heads)... If you aren't spinning the engine that tight then you won't see max numbers.

This 6500rpm peak is seen with either shorty headers or stock exhaust manifolds. Don't have first hand experience with full headers/free exhaust.

As far as a cam recommendation, I'd call up any well know cam company and provide them with your flow numbers (velocity numbers would help greatly as well). Let them know EXACTLY how you intend to treat your engine and they will provide you with a good running cam.