[BruceWilkie]

[QUOTE=firechicken;3854092]

Originally Posted by BruceWilkie

IMO I think you headed in the right direction. quote]

You and I obviously have the same train of thought regarding the installed C/L of my cam. I just can't help but second guess the decision to go opposite to the cam manufacturer's recommendation.
I think I'll give Crane a call and see what one of their tech guys have to say on the subject before I move it either way.

I punched your cam specs into a sim and modeled several different heads based on a 462 ... interesting. Tq peak hovers around 3500 with the various heads from stock to out of box Eheads! and hp peak rpm varies with the heads chosen.

Regardless avg power from 3000 to 500 rpm past power peak rpm all showed an increase in average power with your cam installed at 114 ICL.

ADVANCING to 109 ICL shows increased pk tq in the @3500 range upping the average tq below 3500 rpm and decreasing average power from 3000 rpm up using 500rpm above peak hp rpm.

Retarding your cam much more than 115.5 ICL drops power everywhere so it appears to be happy where it is. another .5 to 1 deg more retard shows a scratch of a gain after 115.5 icl it drops notably so I dont think real world you've got much to gain retarding beyond your present setting taking in chain stretch etc. The low end gains with the 109 icl were at best 6 to 17 ft lbs at peak tq.(depending on flow profile) The hp gains were worth the trade off as reflected in the avg horsepower numbers The most restricted heads still showed a 1.5 hp avg increase from 500 below pk tq rpm to 500 rpm above pk hp at 114 ICL vs 109 ICL. The E-heads showed an avg of 3.5 hp more at 114 vs 109 ICL averaging from 3000 to 500 rpm beyond pk hp(of course all the numbers were bigger). Its pretty much a see-saw around that 3500 rpm pk its suggesting. 109 ICL shows the gains below 3500 114ICL shows the gains above 3500. Because of rpm the HP gains above 3500 are greater than the hp gains below 3500 when you average them out. (FWIW it shows about a 115hp gain from a stockish 6x to a 285 cfm Ehead both at a 15 lb boost limit pk tq hovering at 3500 but pk hp rpm increasing by 1000 rpm) Interesting trends indeed.

Power band trends on my sim have been reliable and even hp has been close yet usually on the conservative side when simulating actually built and dyno tested engines .

[BruceWilkie]

Originally Posted by taff2

.
Bruce,as far as cams are concerned,I've got to figure the cam grinders know far more about this stuff than I do, so I tend to follow their recommendations first and then experiment later if I feel there is a need. I too had thought about retarding the installed C/L for a turbo cam ,but here we have two cam manufacturers,Crane and Bullet, both recommending that the cams should be installed advanced.?

I trust Bullet alot more than Crane but I'll see what it looks like on the sim trends. Seeing as your greater duration and 4" stroke come into play I'm not going to second guess them till I see the trends. What works great in one application doesnt gaurantee anything especially when you get into different strokes and intended powerbands and throw in turbo(s) that might possibly have entirly different different differentials across the engine. With a little luck I might have a model of your turbos. Then compare to different flow files and see how it trends.

I'm more than a little curious. I think I have enough details, if not I'll let you know.