[Steve C.]

"So even when these engines make peak power around 5800, it doesn't mean that they will not rev much higher than that w/o falling on their nose."

I agree, in some instances there is the potential. Nice to have a look at a dyno sheet.

During the second dyno session with my 505 we made a total of 14 dyno pulls. After after all was sorted out with best numbers it made peak power at 6000 rpm (660 hp) but the dyno operator stopped the pull at 6200 rpm where it indicated 646 hp. Down 14 hp.

On a earlier dyno pull it made peak power at 5900 rpm but on that pull the operator stopped at 6400 rpm, here it was down 17.2 hp. Making a dyno pull way beond the 6400 rpm would of been nonproductive.


.

[Steve C.]

Here
Crank: Eagle 4.250"
Rods: Eagle 6.800"
Heads: Unported D-Port KRE aluminum, CAT SS 1.65 roller rockers
Camshaft: Crower hydraulic #60919; Comp 852-16 lifters

502 hp at 5300 rpm and 471 hp by 5700 rpm. Down 31 hp.

Dyno sheet:

http://www.pontiacstreetperformance....455MikeG2.html

If it was a similar hydraulic roller cam it might of pulled to a higher rpm. Also note the 800 rpm power band. The rpm spread between peak torque RPM and peak power RPM. The use of a roller cam typically produces a wider power band, often 1200-1400 rpm.



.

[GTOLou]

Just watched this episode - their ace valve lash guy (lash larue) set valve lash as close to zero as he could w/ the engine cold.

(Most interesting part I picked up from the episode. )

[Steve C.]

Mechanical lifters on a hydraulic cam. The more aggressive the lobe, the tighter the lash needs to be. The tighter the lash, the more you need to pay attention to thermal expansion problems. For example, Comp Cams classic Magnum hydraulic roller grinds usually run fine with solid roller lifters at 0.012-0.014 inch hot. But its newer, more aggressive XE hydraulic rollers get very noisy over 0.010-0.012 hot lash, so for them Comp recommends tightening up the lash to 0.006-0.010 hot. Keep in mind the lash effectively reduces cam duration, especially at low lift off the valve seat. With less duration, peak torque and power occur at lower rpm than would normally be the case for the given combo when running a hydraulic lifter. In other words, the cam acts smaller.

Example Comp XE hyd roller lobe 3315 rated 282 degree at .006" tappet lift and 230 degrees at .050" tappet lift.

A fwiw, that lobe measured 'at the valve' with a 1.5 rocker ratio has 288 degrees duration at 0.0006" tappet lift.

Effective duration 'at the valve' with different lash settings. It assumes a 1.5 rocker ratio.

Measured at 0.006" tappet lift:

279.7 degrees / 0.004" lash
273.6 degrees / 0.008" lash
268.6 degrees / 0.012" lash

Measured at 0.050" tappet lift:

240.9 degrees / 0.004" lash
238.6 degrees / 0.008" lash
236.5 degrees / 0.012" lash

Source:
Comp Cams
Hot Rod Magazine article / Aug 2020

.

[tom s]

On the road paver with solids,Comp told me 6 thou and 200 on the seats.FWIW,Tom

[pastry_chef]

Originally Posted by Steve C.

My 505 with a 255 degree solid roller w/ .022 lash makes it's peak power at 6000 rpm. That was with a Victor intake and HP950 carb )

Was the head around 330 CFM Steve?
How much power difference between points 5800 and 6000 RPM?

[Steve C.]

Yes and no. When the heads were first put together they flowed 329 cfm @.700" with titanium intake valves . They were used on a 700 hp /7000 rpm engine. Now they are on the 505 but for this engine the valves were changed to regular stainless steel and because of their design the heads flow less. My engine builder said about 8-10 cfm less, give or take. He tested them quickly on his flow bench but I have no actual records. It had to do with the valve face, head or stem (?).... I don't remember. Compression ratio is 10:1 / 0.688" net valve lift

654.0 hp at 5800 rpm
659.2 hp at 6000 rpm
( on some pulls peak power was at 5900 rpm)

599.9 ft.lbs.torque at 4100 rpm. Carries over 600 ft.lbs. thru 5700 rpm. Peak torque 639.0 ft. lbs. at 4900 rpm. On some pulls peak torque rpm was at 4700/4800 rpm.

.

[pastry_chef]

Originally Posted by Steve C.

654.0 hp at 5800 rpm
659.2 hp at 6000 rpm
( on some pulls peak power was at 5900 rpm)

Thanks,
My calcs said 5800 RPM peak, I hate to be off. I guess that isn't bad.

[TCSGTO]

Originally Posted by GTOLou

Just watched this episode - their ace valve lash guy (lash larue) set valve lash as close to zero as he could w/ the engine cold.

(Most interesting part I picked up from the episode. )

Lighting lash Brule. I like the zero lash method he used. When I did the hybrid roller deal i shot for .003” cold which is a PITA since there’s nearly that much slop in the the threads of a poly lock/set screw. It’s near impossible to know what the hot lash is with aluminum heads since they have a higher thermal expansion rate than iron and cylinder head temps vary wildly as the engine is run.
Shutting it off after a run and checking lash is close but by then it’s already cooled enough to close the lash a few thou. On really hot summer days after a 1/4 mile pass I could hear the solid rollers tapping on the return road but were quiet once back in the pits. That was with them set at .005-6” cold. Tightening them up as much as possible without hanging a valve fixed that.

[David Jones]

I put Crower Hippo’s on my 230/236 Comp hyd roller in 2013 after struggling with noisy Comp hyd roller lifters. I set them at .005 cold. The last time I checked lash, there was little to no change so I’m going to let’em be for a few years.

I like the engine masters show and have seen every one.