TPI Guy

Has anyone, ever, throughout the course of TPI history taken one cam in one engine, put it on a dyno, taken it out, and put in another cam while leaving all else UNCHANGED. They don't do it with efi, they don't do it with carbs, they never do it. I think the major magazines are afraid to run cams head to head because they might lose an advertisor. Maybe an individual has done it, but at more than 300 bucks a pop, it would have to be a pretty rich individual. Post what you know about the head to head cam comparo.

------------------
355 c.i.
Dart 180 Heads
Lunati 224/224 cam
Harland Sharp 1.5 rockers
Performer RPM Manifold
Holley 600 cfm double pumper
Hooker Super Competition Headers
Flowmaster Exhaust
Competition Engineering Sub-frame connectors
Super T-10
GM posi 3.42 rear
Hurst Roll Control
13.9@102

Vader

Yes, that would be nice to see.

And in a perfect world, we would have realistic horsepower numbers reported by the aftermarket instead of the inflated, "best case" numbers that we usually see. 15HP from and airfoil? Yeah, right, whatever....

------------------
Later,
Vader
------------------
If you want to beat the World, it might reach up and pull you down...
Adobe Acrobat Reader

Matt87GTA

Myron can explain that one to ya......

------------------
1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

Momar

I was wondering what differneces you get in your torque and power curves when you have higher lift and shorter duration vs less lift and longer duration. One example that I have found are the lpe 74211 and 74216. The first has @.50 211/219 and .533 and .560 with 1.6 rockers. The second has @.50 213/219 and .493 and .502 with 1.6 rockers. Notice that the first has a slightly smaller intake duration but higher lifts than the second. What might the differences be in power and drivability(approxomates of course unless someone has used both).

thanks

Ben

airdeano

Some thoughts on choosing the proper cam.
1. Longer rod engines seem to prefer shorter durations and wider lobe separation.
2. Short duration cams with wider lobe separations usually yield much flatter torque curves.
3. Longer duration cams require tighter lobe separation to have any power off the corner.
4. Stock exhaust manifolds or a highly restricted exhaust usually respond well to shorter exhaust duration and wider lobe separation
5. Most unported heads approach 85 or 95 % of peak flow at .400 to .450 lift and do not need or want a maximum valve lift over .540 to.555. Often a low cam lift with 1.65 or 1.7 ratio rockers is very helpful on the intake side as long as lift is kept to about .550. Exhaust is less critical with 1.5 or 1.55 being the most popular.
6. Dyno testing doesn't test drivability or throttle response of the engine.
airdeano