From a solid roller to hydraulic roller

[Geoff2]

Amazes me with silly blanket statements such as 'wide LSA flattens tq curve'......when real world testing proves otherwise.
Three examples come to mind:
- Richard Holdener's LS dyno test 2 1/2 yrs ago of identical cams except for LSA. 108,112,120. The 108 made best low end tq AND best hp. It was equalled in a couple of places but never surpassed & was generally up everywhere.
- Jon Kasse's EMC winning 400 Ford engine. SFT cam, not that big on duration, made 664 hp. 98* LSA, 92 ICL. Hmmmmmmmm....
- Chev 350 race engine, three identical cams except for LSA, 106,108,110. Reason for the testing was to see what LSA did...
110 made the most peak HP....by 3hp over the 106 cam. 108 made 5 hp less.
106 cam made 23 ft/lbs more peak tq over the 110.
The average tq through 7000 rpm, the 106 was 24 ft/lbs better.

I know which cam I would rather have...

[rgalajda]

Don't forget that compression ratio has an effect on determining best LSA.

[F-BIRD'88]

Amazes me with silly blanket statements such as 'wide LSA flattens tq curve'......when real world testing proves otherwise.
Three examples come to mind:
- Richard Holdener's LS dyno test 2 1/2 yrs ago of identical cams except for LSA. 108,112,120. The 108 made best low end tq AND best hp. It was equalled in a couple of places but never surpassed & was generally up everywhere.
- Jon Kasse's EMC winning 400 Ford engine. SFT cam, not that big on duration, made 664 hp. 98* LSA, 92 ICL. Hmmmmmmmm....
- Chev 350 race engine, three identical cams except for LSA, 106,108,110. Reason for the testing was to see what LSA did...
110 made the most peak HP....by 3hp over the 106 cam. 108 made 5 hp less.
106 cam made 23 ft/lbs more peak tq over the 110.
The average tq through 7000 rpm, the 106 was 24 ft/lbs better.

I know which cam I would rather have...

You are overlooking how LSA and thus overlap effect low speed part throttle driving.
Not WOT low end torque.

When the carb throttles are near closed the pressure in the intake is MUCH LOWER than when running at WOT.
The valve overlap alliws exhaust gas to enter the intake during overlap at PART THROTTLE.

this causes the misfire bucking protesting and poor throttle responce when driving in OVERDRIVE gear at low 1750 rpm.
Nothing to do with the power band @WOT.

This big duration tight LSA big overlap RACING cam just does not like to run at 1750 rpm part throttle..
The full race single plane intake does not help either.

A similar LS engine will show the same issue with a Overdrive transmission.

The racey engine wants rpm. It wants to run.
It does not want to run smooth at part throttle at low rpm 1750 rpm. is very low for this racey engine.

WOT dyno testing does not tell you anything about the actual problem...

[F-BIRD'88]

The easy and best solution if you want to keep all the horsepower if this racey cammed 700 HP 540 racing engine is to NOT DRIVE in the GiRlLy mAn GeAr at low speed.
Stay out of Overdrive "Girly mAn's gEaR"
Race engine like gEaRz. Drive it in the right gear to keep the rpm up @ part throttle.
Its not like you are going to save money..
"Are you da gUrLY MaN"?.....
https://youtu.be/2TTVqphm9L4

[Bigchief632]

Amazes me with silly blanket statements such as 'wide LSA flattens tq curve'......when real world testing proves otherwise.
Three examples come to mind:
- Richard Holdener's LS dyno test 2 1/2 yrs ago of identical cams except for LSA. 108,112,120. The 108 made best low end tq AND best hp. It was equalled in a couple of places but never surpassed & was generally up everywhere.
- Jon Kasse's EMC winning 400 Ford engine. SFT cam, not that big on duration, made 664 hp. 98* LSA, 92 ICL. Hmmmmmmmm....
- Chev 350 race engine, three identical cams except for LSA, 106,108,110. Reason for the testing was to see what LSA did...
110 made the most peak HP....by 3hp over the 106 cam. 108 made 5 hp less.
106 cam made 23 ft/lbs more peak tq over the 110.
The average tq through 7000 rpm, the 106 was 24 ft/lbs better.

I know which cam I would rather have...

This thread isn't about max power, it's about drivability. That's one of the problems with these subjects. Everyone has wide open, full throttle on their brain. And your above examples, are application specific, again, they don't apply to everything.

[skinny z]

And your above examples, are application specific, again, they don't apply to everything.

So, you're saying lsa is application specific? And isn't say cut and dried, like maybe a "formula" would suggest?

That's correct. The "formula" is application specific.
And the "formula" wouldn't apply in this case.
As you state, it's a drivability issue and one which requires a different approach. Your example with that Jones cam is an excellent case study.
At least that's my modest take on it.

[skinny z]

That said, with 540 CID, it seems torque isn't the issue.
It could be time related as suggested.
And now there's evidence is some unhappiness at 1750....

[F-BIRD'88]

Whats the specs on that one?

The Voodoo cam is 273/279. 243/249 @.050" 110 (106/114) . .655"/..663". .018" hot.
sorry for the edit.

I suggest getting it custom made on 112 LSA (107/117) for effect on this car with OD trans.
A simple phone call.

He said he had a different new custom cam on the shelf. 254/261 on a 112 i guess

This roller cam could be used to get it custom re-ground with the Voodoo VSR street roller lobes on 112 LSA. say 107/117 phasing. I believe the Voodoo VSR lobes are
intake VSR14. exhaust VSR16. 112 LSA
He'd want to call Lunati to confirm and order.

Another custom cam version could be a single pattern
VSR14 - VSR14 ground on 110 LSA.

[Stan Weiss]

I take it that the engine is still together and in the car with the SR cam. Have you tried loosening the intake and exhaust valve lash 0.005" and seeing if the shortened duration and less overlap makes any difference?

Stan

[F-BIRD'88]

I take it that the engine is still together and in the car with the SR cam. Have you tried loosening the intake and exhaust valve lash 0.005" and seeing if the shortened duration and less overlap makes any difference?

Stan

Keep going + .005" at a time until you get the desired effect in Overdrive..
Do not rev up the engine. just drive it easy at low rpm to evaluate drivability +/-
Ya the valvetrain is going to be more noisey at idle.
This will give you an idea of valve duration effect on low rpm drivability to help direct your next move.
Whats the valve lash that tames it down enough in Overdrive at low speed..???

Do not rev it up..

[CamKing]

Amazes me with silly blanket statements such as 'wide LSA flattens tq curve'......when real world testing proves otherwise.
Three examples come to mind:
- Richard Holdener's LS dyno test 2 1/2 yrs ago of identical cams except for LSA. 108,112,120. The 108 made best low end tq AND best hp. It was equalled in a couple of places but never surpassed & was generally up everywhere.
- Jon Kasse's EMC winning 400 Ford engine. SFT cam, not that big on duration, made 664 hp. 98* LSA, 92 ICL. Hmmmmmmmm....
- Chev 350 race engine, three identical cams except for LSA, 106,108,110. Reason for the testing was to see what LSA did...
110 made the most peak HP....by 3hp over the 106 cam. 108 made 5 hp less.
106 cam made 23 ft/lbs more peak tq over the 110.
The average tq through 7000 rpm, the 106 was 24 ft/lbs better.

I know which cam I would rather have...

And none of those have anything to do with driving down the highway, at 1,700rpm. A high peak torque number is meaningless, when you're driving around at half that RPM.
Lowering the duration, and widening the LSA will fix all the issues with this engine, and will still make good top-end power.

If it was mine, I would stay with a mechanical roller, and go to. 245/252@.050", .680"/.680" Net Valve Lift(after lash), on a 110 ICL and a 118 ECL.

[1980RS]

Well here's my take, GM always uses a pretty wide LSA with their cams, why? because the car needs to get decent fuel mileage and good drivability. My buddy has a 2000 SS Camaro with a 5.7 LS1 with a cam on a 117.5 LSA and it pulls to 6500 effortlessly but like his guy that tuned the car said "here's your torque, you ain't got none" LOL. I also had a 94 Z/28 with a LT1 that the factory cam was ground on a 116.5 LCA and you could lug that car in 5th gear and it didn't pull hard but it has super street manners. Just go to the Comp Cams site and pick out a cam, it's not that big of a deal. Want something for a street type driver keep the LCA on 110 and you will have the best of both worlds and notice that most cams that Comp makes are also on a 110 LCA, then ask yourself "why do they do that?"

[Bigchief632]

Well here's my take, GM always uses a pretty wide LSA with their cams, why? because the car needs to get decent fuel mileage and good drivability. My buddy has a 2000 SS Camaro with a 5.7 LS1 with a cam on a 117.5 LSA and it pulls to 6500 effortlessly but like his guy that tuned the car said "here's your torque, you ain't got none" LOL. I also had a 94 Z/28 with a LT1 that the factory cam was ground on a 116.5 LCA and you could lug that car in 5th gear and it didn't pull hard but it has super street manners. Just go to the Comp Cams site and pick out a cam, it's not that big of a deal. Want something for a street type driver keep the LCA on 110 and you will have the best of both worlds and notice that most cams that Comp makes are also on a 110 LCA, then ask yourself "why do they do that?"

You know why they do it. It's a good compromise to cover a wide range of potential customers wants and needs. It works pretty well for all of them. If they needed something different, or really wanted to maximize their exact combo, they'd call and get something custom.

[F-BIRD'88]

A off the shelf comp XR274R10 would serve that purpose.

comp #11-770-8 It should check 238/244 in the engine.
You can play around with the installed position for effect.
My intuition and experience is telling me to still get it ground on 112 LSA.
Nice its just a phone call away to do that.

[Tom68]

Amazes me with silly blanket statements such as 'wide LSA flattens tq curve'......when real world testing proves otherwise.
Three examples come to mind:
- Richard Holdener's LS dyno test 2 1/2 yrs ago of identical cams except for LSA. 108,112,120. The 108 made best low end tq AND best hp. It was equalled in a couple of places but never surpassed & was generally up everywhere.
- Jon Kasse's EMC winning 400 Ford engine. SFT cam, not that big on duration, made 664 hp. 98* LSA, 92 ICL. Hmmmmmmmm....
- Chev 350 race engine, three identical cams except for LSA, 106,108,110. Reason for the testing was to see what LSA did...
110 made the most peak HP....by 3hp over the 106 cam. 108 made 5 hp less.
106 cam made 23 ft/lbs more peak tq over the 110.
The average tq through 7000 rpm, the 106 was 24 ft/lbs better.

I know which cam I would rather have...

Richard doesn't check the installed position and you're looking at cams from different manufacturers and of course he doesn't ever test for drivability.