When I get essentially identical TQ and HP curves, I look at the VE (volumetric efficiency) and then pick that cam...........

(I have the older dyno2000).


I figure the cam with the better VE will get better mileage (don't know if this is true, it's just my assumption)

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

looked again at the standard vs the reversed profiles, looking to identify an effect of the duration and lift change.
for the cams I have under consideration, made a one to one comparison of standard and reversed profiles while holding LSA and intake / exhaust centerlines constant.
the hp and torque curves show the RDP lagging a bit compared to the standard profile until about 3200 rpm, then the lines flip and the RDP has an advantage past the peak. That condition shows on both the hp and torque curves.

http://www.flickr.com/photos/13718356@N02/5416643734/

For volumetric efficiency, the standard has an advantage across the rpm scale, however between 3500 and 4500 rpm, the gap between the two disappears.

http://www.flickr.com/photos/13718356@N ... otostream/

DT,

In your simulation did you put in cylinder head flow numbers?

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Joshua

there is an option to enter actual flow numbers, after porting, I would want to run it across a bench to get real numbers.
Since I do not have those yet, I am selecting the program options
Cylinder Head, 2 valve wedge, low performance pocket porting
Intake Valve 1.700 Exhaust Valve 1.440
Compression Ratio 8.5
Combustion Chamber, Disk Center Plug

That may be why you're not seeing the expected results from the RDP cams.

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Joshua

I can believe that, the charts indicate that at the highest flow the rdp gives a stronger response.

There have been a couple of posts that have numbers to use for stock head and a "ported race head" flow numbers...That brings the realm back into reality...I remember having to alter a fair amount of settings in Dyno 2000 to get it to be close to reality...the default flow numbers for "stock" valves were a set of 351 cleveland valve diameters...after tweaking that with flow numbers, I'm still not convinced it has the correct settings to approximate the hyperpak intake...the numbers plugged out for a tuned port manifold leaves the engine way too short compared to the real world numbers, and the "open manifold" doesn't act like that long ram manifold either...
Of course getting it close then plugging it into Drag Sim 5 then becomes even more fun....I see it might be more beneficial after a 13.5:1 slant build, to just install a surplus engine out of an F-4 Phantom...which seems to allow an A-body to break the 5 second 1/4....assuming it stays straight (body and tracking) and the driver and rubber doesn't melt along the way...


-D.Idiot

Some head flow numbers here:

http://users.erols.com/srweiss/tablehdc.htm

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Is it possible to get my mechanical cam reground to one of these hydraulic grinds? I figure my cam is now pretty well matched to the bearings it rides in so I shouldn't introduce a new cam to old bearings. I also don't want to get very far in the engine and start replacing bearings. Custom length push rods aren't a big deal.

Yes, you can have a mechanical cam core reground with a hydraulic profile. You'll need to have the rear cam journal grooved to provide full-time top-end oiling and swap in hydraulic rocker gear of course.

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Joshua

Josh,
What are the correct dimensions and position for this groove or will most cam grinders know about this for \s? Thanks

Any feedback on the groove dimensions? Also will stock replacement hydraulic lifters work with these grinds? What if I wanted to increase to 1.6 rockers: does that effect lifter choice?
What I understand is since grinding these lobes takes some off the base circle and increasing compression takes some off the head, it is possible to use stock length push rods if the distance is still within tolerance? How much adjustment is allowed in the rockers? Thanks

on the factory cam out of my 83 D150
groove is
.075 wide
.034 deep

http://www.flickr.com/photos/13718356@N ... 869063629/

regards
DT

There are no choices in hydraulic lifters for the slant nor are there any choices for hydraulic lifter compatible rocker arms. In other words, no 1.6:1 juice rockers. There is no adjustment on the hydraulic rocker arms.

I have a set of H2089 lifters in Clevite boxes. There is .190" of plunger travel in these lifters. That's a lot of built-in adjustment, but you cannot bottom out the lifters. I would try to maintain at least .020" travel otherwise the lifters might go solid and hold the valves open if the engine is worked hard and gets hot.

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Joshua

DT,
maybe i missed it but what CR are you using in the sims? any chance you might be able to a sim with the stock cam,350cfm, ect., along with the cam#4 you have listed with a 9:1 cr and 13:1 cr.

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1976 Plymouth Feather Duster
2002 Dodge Dakota 4.7l v8