Camshaft possibilities?

[Booyah45828]

Unless I'm missing something when inputting the numbers posted above?

Looks like it calculated overlap based on .050" lift values:

I don't know about the accuracy of those numbers, I didn't see a source provided. I'd say they're probably right though, and you inputted them correctly too.

But you about need advertised duration numbers as well, otherwise you're guessing on the lobe intensity from 0 to .050" lift. From the looks of it, they guessed something pretty steep which is why the #'s are off.

In the graph it shows the intake opening ATDC and the exhaust closing BTDC, which is something I've never seen.

 

[ttman4]

Oh come on you know you want to work on the truck in those central oregon snowy days

I tell myself those wonderful snowy days in Central Oregon or fun, guess what though they are not!
How ever though, year around I can tell Carol “I need to go change spark plugs in Bessie” and that keeps me from washing dishes and vacuuming. Ha ha

 

[Rusgo]

I don't know about the accuracy of those numbers, I didn't see a source provided. I'd say they're probably right though, and you inputted them correctly too.

But you about need advertised duration numbers as well, otherwise you're guessing on the lobe intensity from 0 to .050" lift. From the looks of it, they guessed something pretty steep which is why the #'s are off.

In the graph it shows the intake opening ATDC and the exhaust closing BTDC, which is something I've never seen.

The R&D numbers were copied and pasted from their website.

The stock numbers were verified across a few manufacturers.

Thinking that R&D used to have the stage 2 cam, and that one had overlap. It was the higher RPM turbo cam. The current stage 1 is more of a torque cam, so no overlap.

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[Chief]

Yes it do! Back in my trucking days I had an old 1693 Cat that would pull 22# summer, 34# in cold winter & get there quicker. Same fuel, same hills, same kind of load.
My '90 7.3 w/088 ATS used pull 8-9# summer, 11-12#+ at about -10* deg, same settings, same hills, etc, & get there quicker!!
But one of these days I want to do a cam, soon as I can get round to doing some injectors first...... & get my SHOP BUILT!!!

If I had a shop, I’d never leave lol

 

[jaluhn83]

Pressurized intake means the cam matters quite a bit less because the greater pressure differential makes the exact flow Dynamics less critical - same reason a tuned intake is less important. Also, the lower RPM helps make it less sensitive.

Keep in mind also that the piston/valve clearance puts limits on what can be done with the cam period.

 

[Booyah45828]

You're correct on that thought, the problem is that with us being turbo charged, we also have a pressurized exhaust. That right there is something that most don't know or understand, which is why a good efficient turbo can really make an engine shine, while a bad one will make it a dog.

You need some amount of overlap for scavenging, but not too much, because the exhaust is usually under higher pressure then the intake.

I think you're also correct on the lower rpm making it less critical. Lower rpm means the valve is open for more time per revolution.

I think the more important area to look at as far as cams go would be when the intake valve closes. That, combined with overlap, would dictate whether a cam would be more directed for lower rpm or higher rpm usage.

 

[gfemling]

Positive feedback on benefits of newer Type4 cam- installed in 6.9 w hypermax intercooled system and saw usable low end torque drop 300-400 RPM. Before boost was practically none below 2k; after usable boost began building around 1600. Very satisfied!

 

[gfemling]

To clarify on above post- had turbo and intercooler before; only real change was installing cam.

 

[robert alston]

so did your cam grind charge or just the company that ground the cams

 

[Rusgo]

Positive feedback on benefits of newer Type4 cam- installed in 6.9 w hypermax intercooled system and saw usable low end torque drop 300-400 RPM. Before boost was practically none below 2k; after usable boost began building around 1600. Very satisfied!

Nice. I tend to agree that a properly sized turbo makes flow and timing characteristics less significantly impacting, but for as much consistent feedback that there is from everybody who uses Typ4, there must be some optimization going on. Cant argue with real world results.

Low RPM spooling, efficient upper RPM flow characteristics, wide usable torque curve, much more power over facyory, good reliability....not too greedy wanting it all!?

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[IDIBRONCO]

not too greedy wanting it all!?

Since these are IDIs and there's no cake involved, I don't think it's too greedy at all.