David Vizard. High Lift Low Duration ?

[Cobradriver]

I am binge watching Mr. Vizard's Power Tec 10 videos now. Cool stuff. He seems to have a very practical and highly observant, curious approach. I had a chat with an online cam tech recently. When it came to high lift (approaching 0.7" gross) I got the impression that low RPM (1500-2200) may suffer as the question of torque converter stall came up. Guessing that the port velocity might not be enough for what folks consider a well behaved street car. Displacement being a huge factor. Just a reminder that I'm the dumb blond around here but learning as I go.

That's why I like stick cars. It's fun when it idles at 1400-1500rpm with a lope.
Honestly even with a pretty stout cam, the overdrive in a T56 with 3.73 isn't bad at 75-80mph....

[Cobradriver]

When speaking in camshaft terms, everything is relative, general, and vague.  It's only when you get into one single specific application that you can zero in on where the lift should be, where the duration should be, where the overlap should be, etc.

For instance, what's high lift to you?   High lift to me is 1.050", but I get some customers who stand with mouth agape when I suggest to them a .570" lift camshaft. 

It's very common for me to run .630"-.650" lift at the valve on a hydraulic roller street cam.  Lift in and of itself does not affect rpm or rpm manners, unless the lift is too high for the cylinder heads and the heads are turbulent at that particular lift.   

However, too much duration can certainly get you into trouble when it comes to an engine's behavior on the street. 

What I have found out over the years is that most guys associate the lift with how the cam will behave.  That's certainly not the case.  "I've got a .600" lift cam in this thing!"  really tells me nothing except that it has .600" lift.  It tells me nothing about where the rpm range will be, how it will sound, or if it will have enough vacuum to run the brakes.   True camshaft specs will involve .050" duration, .200" duration, advertised duration, lift, how much overlap it has, and where the valve events take place.

LOL...I get a lot of funny looks when I tell people I'm right at .700 lift in a solid roller and I drive the car 6-10K a year.

When I started down the solid road, the tech hadn't been hashed out on the hyd roller stuff yet(20 years ago). Knowing what I do now, I could probably make the hyd roller cam I had work better....

[Blueoval77]

It's like anything else:  you have to experiment and learn.   With the right valvetrain and camshaft, I have no issue going to 6500-7000 and even higher with a hydraulic roller.   Would I always choose a hydraulic roller over a solid?  No.  Do they work in the right application?  Absolutely.

I'll leave this here:

https://www.youtube.com/watch?v=C_JY47anClA
[/quote]

Well getting them to spin is one thing but they are never going to be predictable in all other concerns . Its going to decide to idle however it wants to idle given engine temp or how the clouds are positioned in the sky that day. You will make a pass and come back to the pits sounding like you changed the engine down in the shut down area  .
Mechanical is just that. Its always going to be what it is . Just like Hydraulic is always going to be what it is . Mechanical is affected by things and hydraulic is affected by those and a list of others on top of that....
Small dive to the store engines , yeah I get it.... I experimented many years ago and yeah , I get it. "They have come a long way"  , but just that statement says everything you need to know . Solids are just solids....
Its always good to avoid anything that has the statement "They are much better than they used to be" attached to them....Sorta like that crack head every town has , Yeah they got older and they are much better than they used to be.... But they are still a crack head....   

[blykins]

It's like anything else:  you have to experiment and learn.   With the right valvetrain and camshaft, I have no issue going to 6500-7000 and even higher with a hydraulic roller.   Would I always choose a hydraulic roller over a solid?  No.  Do they work in the right application?  Absolutely.

I'll leave this here:

https://www.youtube.com/watch?v=C_JY47anClA

Well getting them to spin is one thing but they are never going to be predictable in all other concerns . Its going to decide to idle however it wants to idle given engine temp or how the clouds are positioned in the sky that day. You will make a pass and come back to the pits sounding like you changed the engine down in the shut down area  .
Mechanical is just that. Its always going to be what it is . Just like Hydraulic is always going to be what it is . Mechanical is affected by things and hydraulic is affected by those and a list of others on top of that....
Small dive to the store engines , yeah I get it.... I experimented many years ago and yeah , I get it. "They have come a long way"  , but just that statement says everything you need to know . Solids are just solids....
Its always good to avoid anything that has the statement "They are much better than they used to be" attached to them....Sorta like that crack head every town has , Yeah they got older and they are much better than they used to be.... But they are still a crack head....   
[/quote]

I respectfully disagree.

[gt350hr]

   Me too , respectfully as well.

[blykins]

 "They have come a long way" doesn't just apply to the hydraulic rollers.  Fifteen years ago, pressure fed solid roller lifters were just coming out and before then, guys were getting about 3000 miles on a solid roller lifter. 

With engines, "they have come a long way" should apply to everything, all the time.  I don't ever want to get stagnant on engine development, especially engines that I love working on.

[chilly460]

Watched some of his videos last night.  I think we essentially know the concept of "biggest flow through smallest port" is best, but he quantifies it with the airflow per volume measurements.  I like that, like many of our guys here, he focuses on tq/ci as his focus of an engine's efficiency/quality.  I don't know if I have the budget and energy to do it, but it would be nice to buy his intake program and run numbers on our many 445-462-482 combos and start to see where the bottleneck occurs.  If...big if...you could take a typical 462ci combo and then run a prediction on it with the TFS versus say Brent's new ported TFS, that would be hugely valuable. 

[Blueoval77]

"They have come a long way" doesn't just apply to the hydraulic rollers.  Fifteen years ago, pressure fed solid roller lifters were just coming out and before then, guys were getting about 3000 miles on a solid roller lifter. 

With engines, "they have come a long way" should apply to everything, all the time.  I don't ever want to get stagnant on engine development, especially engines that I love working on.

As I said , Solids come with their own set of issues or caveats  , Hydraulics share those same caveats and then pile some on top of that . Its just logics 1 Oh 1 to remove as many of these as you can when looking for a positive result...

You know many years ago I had a hydraulic winsor I beat on pretty bad and that thing would throw the lifter out into the valley and leave the unbent pushrod back on the cam lobe bouncing around.... I mean it gets some points for defying physics but scars developed when young only get deeper over time....   

[blykins]

Well, when the combo isn't right, nothing will work. 

[gt350hr]

   Solid roller lifters have ALWAYS been prone to failure because of one thing , valve lash. Pressure feeding helped and some feel the bronze busing is the answer. "I" like the tight lash concept to limit the pounding.

[Blueoval77]

That whole thing is pretty annoying as it doesnt need to be . The aftermarket went so far as to say they now sort the needles better and blah blah blah but in the end it all comes down to the quality of parts they are putting in there. ITs a simple issue and you are telling me they cannot solve it ? Or is it that they cannot solve it at the price point that most want to pay ? The bushing just prevents all the little stepchild rollers from scattering here and there in your inards....
Of course its the lash and the beating..... The old 6.9 internationals were pretty much unkillable (Hyd Roller) and they didnt exactly see easy lives... Its not like the roller lifter is some new fangled entity...

[Joe-JDC]

Hydraulic rollers fail, also.  I have a 351W stroker under the bench that lost a roller lifter and wiped out the camshaft, messed up a couple of cylinders, piston skirts, and oil pump.  Will need overbore, new pistons,  turn crankshaft, recondition rods(nicks from needle bearings), and new camshaft, oil pump, pick-up tube, lifters.  Was a custom hydraulic roller camshaft with lots of duration and lift.  Nearly square looking lobes.  I have a Comp Cams solid roller in my '86 GT with 383W stroker that will probably get changed out soon for a HR camshaft just as a precaution against another lifter failure.  Going with less duration, high lift.   Joe-JDC

[blykins]

That whole thing is pretty annoying as it doesnt need to be . The aftermarket went so far as to say they now sort the needles better and blah blah blah but in the end it all comes down to the quality of parts they are putting in there. ITs a simple issue and you are telling me they cannot solve it ? Or is it that they cannot solve it at the price point that most want to pay ? The bushing just prevents all the little stepchild rollers from scattering here and there in your inards....
Of course its the lash and the beating..... The old 6.9 internationals were pretty much unkillable (Hyd Roller) and they didnt exactly see easy lives... Its not like the roller lifter is some new fangled entity...

You can't solve the issue.  Anytime you have something with lash and high spring pressure, it will fail eventually. 

[gt350hr]

 +1

[475fetoploader]

+2