Max RPM of Jeep Engine

[Plechtan]

Not familar with it, Assuming it has two fewer cylinders, its cam is not as long, which means its natural frequency would be much higher.

The Hesco 3.0L is a 3" stroke x 3.75 bore, It is a 6 cylinder motor.

[gradon]

There's some 2.5ls 4-bangers out there that were bored and stroked to 3.0l and I've read of their ability to rev in the 7K+ range, just to clarify.

[Alex22]

CUSTOM OVER HEAD CAM FTMFW!!!

I used to love blitzin' my little honda engine to 8000 RPM!

Has anybody ever thought about using something called a "Lost motion assembly"? My idea would consist of a follower that rode on the BOTTOM of the camshaft with maybe 50PSI of spring pressure.

If I understand your question correct, it would take a lot of work to make one of those work.

~Alex

[Alex22]

The only timing chain I've seen broken was in a SB Ford that was in a road race car. Lets just say the engine had some "issues" and the only reason the driver didn't keep on driving it was because part of the rod made its way up between the cam and the cam tunnel stopping the cam instantly and snapping the chain. How many other people have seen a timing chain actually break and what was it in?

~Alex

[TurboTom]

CUSTOM OVER HEAD CAM FTMFW!!!

I used to love blitzin' my little honda engine to 8000 RPM!

Has anybody ever thought about using something called a "Lost motion assembly"? My idea would consist of a follower that rode on the BOTTOM of the camshaft with maybe 50PSI of spring pressure.

I worked on an overhead cam conversion yerars ago..but like I said the drawings are long gone. I will look into this again I'm sure.
Back then I was going to use lifter buckets, but I would go with finger followers now.
The "lost motion assembly" you mentioned I believe is called a Desmodronic, Ducati has used it for years
Cool Stuff

[gremlinsteve]

yep..desmo is ducati..created by mercedes in the 30's and or 40's time table..

been around for years.


steve

[Mgardiner1]

I see. I just used the name of the assemblies from a VTEC honda head. Both intake and exhaust valves for 1 cylinder had 3 cam lobes and 3 lifters to go with it. The middle lifter was obviously not above a valve. The outer 2 cam lobes are normal lift, the middle lobe was a higher lift and longer duration. At 5500RPM, an oil pressure switch would activate a set of hydraulic pistons that would lock the middle cam lobe/follower assembly, with the 2 outter ones, thus giving the higher lift to both valves. ANYWAY, the middle follow was supported by what honda called a "lost motion assembly" that simply provided enough spring tension to have it ride the face of the cam.


And yes Alex22, it would be VERY difficult to engineer....

[TurboTom]

I see. I just used the name of the assemblies from a VTEC honda head. Both intake and exhaust valves for 1 cylinder had 3 cam lobes and 3 lifters to go with it. The middle lifter was obviously not above a valve. The outer 2 cam lobes are normal lift, the middle lobe was a higher lift and longer duration. At 5500RPM, an oil pressure switch would activate a set of hydraulic pistons that would lock the middle cam lobe/follower assembly, with the 2 outter ones, thus giving the higher lift to both valves. ANYWAY, the middle follow was supported by what honda called a "lost motion assembly" that simply provided enough spring tension to have it ride the face of the cam.


And yes Alex22, it would be VERY difficult to engineer....

Sorry, I misunderstood. The Vtec and a desmo would be 2 different systems. A desmo system actually uses the cam to open AND close the valve. (OHC)
The rocker is forked to ride on both sides of the cam and the other end is "attached" to the valve. So the valve HAS to follw the cams profile. They use a small tender spring to help it idle. Groovy stuff but way to much work for what I want to do. I would like to finish the OHC conversion someday though.

[Plechtan]

If you are looking for an overhead cam on a Jeep Inline 6, take a look at the Tornado 6 used from 62 to 68? I know i saw one in a M715 Pickup. It was used in the Wagoneers. It had a single overhead cam, right down the center of the head. It had Hemispherical combustion chambers, Intake canted to the right and exhaust to the left. The rockers were directly between the cam and the valve. Very advanced for 1962.

[TurboTom]

I'll look into that. But I will probaby just build my own. I am strange that way

[Plechtan]

If you do, it won't fit under the hood of a Cherokee or Comanche

[SIXPAK]

I'll look into that. But I will probaby just build my own. I am strange that way

He's not kidding about the strange part guys. Must be why he and I get along!

[TurboTom]

Plechtan:
You mean it won't fit under a stock hood
The F/G hood that is on my Spirit has plenty of room


SixPak:
You got that right!

[1bolt]

Not familar with it, Assuming it has two fewer cylinders, its cam is not as long, which means its natural frequency would be much higher.

The Hesco 3.0L is a 3" stroke x 3.75 bore, It is a 6 cylinder motor.

Sounds like someone should be asking Lee why it doesn't have a harmonic? Then again maybe it does, and the short stroke allows it to be revved through so fast that it has no ill effects.

Guess I need to go school myself on HESCO's oddities before I go assuming things.... that's twice this week.

[Plechtan]

Nobody seems to know why the motor has a Cam harmonic, including Hesco. The 3.0L motor uses a 3" stroke billet crankshaft, which I would assume has 12 counterweights. The standard Jeep 4.0 crank has only 8 counterweights. The 258 crank has either 4 or 12. I would like to see some data on the type of cranks used on the engines that have shown the cam harmonic.