calculating overlap and lsa, or lca etc.

[Grumpy]

in most engines use of a wider 110-114 lsa will improve idle,
and in some cases a minor improvement in lower rpm fuel economy
a tighter 104-108 lsa will boost torque and in some cases peak power,
so every choice is a compromise,
and your compression ratio, fuel octane, engine displacement and gearing effect results
personally Id suggest the a tighter 106-108 lsa in many performance cam choices,
but talk to the tech guys at crower,
, erson, lunati, explain what you want, they will help out

crower 619.661.6477

erson 800-641-7920

lunati..662-892-1500

 

[Indycars]

I think the best way to answer your questions would be by running some engine simulations. I have Dynomation 6, it would have a much more sophisticated calculations than anything one of us could come up with and then display the results such that we all can understand them. It will be so much easier to see where and how much the HP/TQ curves move when looking at the graphs overlaid on top of each other.

Dynomation-6 Engine Simulation

Motion Software Secure Purchase

If this sounds like something you would like to do, then please add the information requested below. It might be Monday before I can get to running the simulation, but if I can it will be sooner. Depends on when I get all the info below.

Let's start with what you have now for our baseline.

Start a new thread.with the "Input Variables" below in the section linked to below.

Engine Combos and Dynometer Database

Dynomation 6 Input Variables

Bore & Stroke:
Displacement: cubic inches:
Rod Length:
Heads Make/Model with flow numbers: Flow (CFM) at several lift points.
Combustion Chamber Size in CC’s:
Dome Volume: For a domed piston use a (-) negative number.
Valve Relief Volume: For a piston with valve reliefs or dish, use a (+) positive number.
Deck Clearance: (Piston to Block Surface)
Head Gasket Bore:
Head Gasket Thickness:
Valve Sizes Intake/Exhaust:
Intake Manifold Type: [Single or Dual Plane]
Manufacture/Model #:
Carburetor Size or EFI (CFM):
Blower/Turbo Make/Model:
Belt Ratio:
Header Tube Diameter: 1-5/8", 1-3/4", 1-7/8", 2.0"
Cam Part Number:
Cam Specs: Need all 8 valve timing events at seat-to-seat and at 0.050” plus lobe lift or valve lift OR post Cam Card OR give me what you have.
Rocker Ratio - Intake/Exhaust:
Cam Installed per Cam Card, or Retarded or Advanced:
Fuel Used: Gasoline (Octane ?), Methanol, Ethanol, E85 .....
.

 

[Grumpy]

THANK YOU RICK!
I'm sure that might be helpful

as several of my mentors impressed on me over decades
" you have to finish races in good condition to win races,
peak power numbers may be impressive,
but if it hurts durability to get them you'll lose races"
and the car will be a bottomless money pit!
very high durability is very desirable, impressive peak powers desirable,
but, always choose rock solid durability

if you find it hard to do the math, a 10.5:1 compression ratio, 383 sbc with 2.02 heads requires a 106 lsa

so cams like this in a 10.5:1 compression 383 with the correct gearing etc worked very well.

http://grumpysperformance.com/crane110921.jpg

 

[Grumpy]

keep in mind as always mandated proper clearances,
& checking valve train geometry, having proper valve spring load rates,
and having abundant lubrication flow rates is critical to proper durable function
and yes there's tips in the video that help you make good choices

remember the LSA ( lobe separation angle) (ground in can't be changed on single cam engines)
and LCA can be advanced or retarded and will only be the same., as the LSA if the cams installed at split overlap or strait up

related links

checking piston to valve clearances

this is an old post I got asked to repost, naturally the first step is to install and correctly degree in your cam, https://garage.grumpysperformance.com/index.php?threads/calculate-required-octane-for-compression-ratio.2718/#post-50341...

garage.grumpysperformance.com

cast roller cams and high spring pressures don't generally work well

running a cast core roller cam on the street with significantly more than MINIMAL spring pressures for the intended application, IS JUST asking for valve train problems, but a balance must be maintained, if the valve spring is too weak and allows the cam lobe to throw or loft the lifter at...

garage.grumpysperformance.com

valve train clearances and problems

you might want to read thru these links and sub links it will help you avoid costly mistakes http://www.summitracing.com/parts/pro-66830/overview/ https://www.harborfreight.com/multipositional-magnetic-base-with-fine-adjustment-5645.html...

garage.grumpysperformance.com

sellecting valve springs, and setting up the valve train

How do you determine the spring pressure needed to keep the valves under control for a given lift, duration, and max rpm. It might take you several hours to read thru all the links and sub links but its time very well spent as it could save your engine from destruction and save you thousands of...

garage.grumpysperformance.com

sources for pushrods and check info you might need

you might want to CAREFULLY, read thru these links and sub links, it will help you avoid costly mistakes, a half hour reading the links, could save you hundreds of dollars and hours of work theres at least a few hours of very worth while , and quite useful reading in this thread and links that...

garage.grumpysperformance.com

degree it in correctly and get it to last,cam install info,

IM frequently asked (why bother degreeing in a cam, the timing set comes with index marks to install it?) it basically comes down to, a question of do you accept a random install where the timing can be almost any place randomly or do you insist on maximizing the engines potential and know...

garage.grumpysperformance.com

oil system mods that help

heres a short list REMEMBER the object or goal in building and maintaining the lubrication system is too maintain a 100% dependable pressurized cooling flow of lubricant to the bearings, rockers ,valves etc. your most important tool, is your ability to think about how things are supposed to...

garage.grumpysperformance.com

https://iskycams.com/tech-tips-2000.html

heres a very useful link
yes THE VALVE SIZE VS THE CYLINDERS DISPLACEMENT MATTERS< ESPECIALLY IN THE CAM AND HEADERS DESIGN SELECTED

 

[Grumpy]

watch the video very carefully, listen very carefully, take a few notes,
and go back and re-listen if you miss a few points
its basically showing how this chart works and how it needs to be modified slightly
with higher compression or larger displacement or if you use a BBC vs a SBC