D V Live now.

[digger]

skinny z wrote:
> What video are you referring to?
> It could be a full time job keeping track and I'd rather not.
>
> On a similar note, one of DV's cohorts has a channel now and he was
> recently extolling the virtues of a tighter LSA.
> I watched until his 3 cam test proved flawed enough for me to bail.

Jon posted it on previous page and quoted it.

Another one of the flaws when 128 was presented was that the 128 derived LSA makes more power everywhere. This has been shown to be false in many articles and by Richard Holdener. It might do so when the cam is nowhere near the correct spec but it’s a trade off

[SchmidtMotorWorks]

What video are you referring to?
It could be a full time job keeping track and I'd rather not.

On a similar note, one of DV's cohorts has a channel now and he was recently extolling the virtues of a tighter LSA.
I watched until his 3 cam test proved flawed enough for me to bail.

It's easy to take an engine that is well developed for a street driven applications and say "that will make more power is you narrow the LSA".
Most of the time it will make more power, so what? It makes the car unpleasant to drive.

It's like saying, "you can save money by turning your thermostat down when it is cold out"; who didn't know that?
But now you are living in an unpleasant home.

The same scenario exists in a performance aftermarket company.
If you want to make a part like an intake manifold for a late model car like a Coyote Mustang or a Hemi Challenger, it might look easy.
In reality they are amazingly well optimised for their intended purpose. The only opportunity the aftermarket has is to redefine the requirements.
Usually that means raising the RPM of peak HP at the expense of driveability.
It isn't the 60's anymore when manifolds had very little R&D in them.
I guess that it might be accurate to say that the intake manifold on the new Dodge Challenger has more R&D in it than all of the 1960s muscle car engines combined.

Same is true for all other parts.

At Edelbrock we would get people to bring in new donor cars to develop new parts for them, as they couldn't afford to buy new cars for that themselves.
Sometimes the part would be developed and achieve the power goals.
Then a few months later, the guy would come back asking if we could make it back the way it was.
Peoples appetite for HP is often greater than their stomach for poor drivability, fuel economy, emissions etc.

The performance aftermarket has a slim chance on improving on a modern OEM part without losing in some area.

[skinny z]

But Mr S...
What would you say if this time around I DID want something edgy?
The drag strip is 20 minutes down the road. Literally.
I've had a half dozen or so (not counting my first foray into hotrodding that's too long ago to drag up) of the "driveable" engine builds. While they're nice, given the chassis package they've been wrapped in, they've been unspectacular.
I'm of the mind, but as of yet undecided until I have that conversation with my cam grinder, to build a drag racing engine.
Something with a narrow RPM band as I have the converter and a very low 1st gear (4L60 + 3.73's) and it's something that would see very little street time.
No concern for the streetable part as the converter seems to handle the low revs situation very well and to and from the track isn't a big deal.
Besides, the drag week guys have taken the streetable bit to a level that's basically unreasonable so who am I to argue?
Given that situation, and considering that the cam and associated valvetrain are all that's left to spec, does that narrow LSA, as per that controversial 128 guideline (I tick all the boxes there by the way), make any level of sense to you?
I'm not looking for a spec here, but a move to a 108 or 107 LSA with overlap and duration to suit might make a better drag racer than the tried and true wider seperation with broader reach but less peak.
Just asking since I kind of have your attention.

[SchmidtMotorWorks]

I would not use any "rule of thumb" approximations to develop a set of cam card specs.
I certainly would not use any guidance that was not based on the gas dynamics if I had the tools to do so.
Leave the whole thing up to a professional that has the tools and experience to do so.
Cam card specs are only the tip of the iceberg in a cam design.
Imposing a set of cam-card specs on a cam designer is a terrible idea.
BTW it should be a "valvetrain" design.

You have mentioned "max effort" previously.
What does "max effort" mean?
What do your heads flow?
What compression will you have?
What can your pistons handle for valve clearance?
Will you be running light weight titanium valves?
Will you be running hi-end rockers?
Will you have hi-end pushrods?
Are we talk roller cam? Hydraulic or solid? What guided the decision?
Each of those decisions makes a difference in the cam design.
The cam designer might point out something in your combination that is not compatible with the rest or your goals.

Let him know your budget for valve train parts.

[skinny z]

That's as reasonable an answer as one could expect.
FWIW: I've yet to get the last few measurements (port size, MCSA, chamber volume (after rework), verify piston to deck, then possible CR's) but once in hand, I feel I can proceed to the valvetrain spec with whoever that'll be. Probably Mr Jones.
That said, when I mention max effort, it's down to the cam at this point as all of the other parts are in place. So it's really a maximum effort of the parts in play with the cam determining the final result.
That's for your input. It IS appreciated.

[SchmidtMotorWorks]

Congratulations, it sounds like you are on a good path.
Jones won't disappoint you.

[SchmidtMotorWorks]

That's as reasonable an answer as one could expect.
FWIW: I've yet to get the last few measurements (port size, MCSA, chamber volume (after rework), verify piston to deck, then possible CR's) but once in hand, I feel I can proceed to the valvetrain spec with whoever that'll be. Probably Mr Jones.
That said, when I mention max effort, it's down to the cam at this point as all of the other parts are in place. So it's really a maximum effort of the parts in play with the cam determining the final result.
That's for your input. It IS appreciated.

Are you using any software to help your understanding?

If not, begin with PipeMax, no matter how good of simulation software you have, it is the fastest way to get to a good setup.
I always run PipeMax first then use those numbers in a 1D software like Dynomation or EngMod4T.
Sometimes you will make some progress in your 1D software and then find yourself in a ditch wondering how to get back to where you were.
Sometimes the fastest way to get back on track is to go back to the PipeMax numbers and start over.
Sometimes PipeMax will be so close to ideal, you won't find much improvement on it.

[skinny z]

I've been indulging in various software for the last couple of decades. They're all little dated though. My version of PipeMax I believe is 2.0 !
That said, yeah, I use PipeMax for some specific development and then transfer that to a sim program. Lather. Rinse. Repeat.
I'd like to update PipeMax (I've talked to Larry about it) and also get a newer engine modeling program. I picked up DynoSim in the 90's so there's room for an upgrade there too (DragSim too). The two you've mentioned, Dynomation and EngMod4T, are at the top of the list. I've been looking for some trial versions and want to experiment with those before I pull the trigger on the whole shebang.

In my case, because I have the heads and the basic engine architecture in place, I'm using PM to get the exhaust sorted. That's where the biggest gain over my previous combination will come in. I was always very exhaust system limited due to the chassis platform and the cars use. This go round, I can focus more on a track specific deal, as in open headers (via cutouts) and have used PM to establish approximate collector dimensions. That'll be something that gets further tuning when I have detailed cam specs. Then back to PM again exactly as you've described.
There'll be some induction side investigation too. While I have a dual plane intake and 750 VS carb, that top end stuff is easier to remove and replace. Much more so than an in car cam swap.

You know, I've taken a few shots here at ST because of my indulgence in the virtual. Truth is, circumstances have curtailed my car development to only that for the last three years or so. It's just this past year that I've moved along in the hard parts department. But that only intensifies my need for simulations as things get refined at this point.
It's good to know that a ST personality such as yourself gives props to the software side of things. Personally, I can't see how vehicle engineering can proceed without it.

Thanks for the feedback.

[SchmidtMotorWorks]

The benefit of using a 1D sim is that they actually help one understand what is going on in an engine.
People often confuse following a recipe with actual understanding.

Dyno testing can confirm what works to some extent but it does very little to inform you of what is actually happening with regards to the gas dynamics unless you have a pressure measurement system like TFX. I have one, but it isn't for everyone, just one spark plug was over $1000 3 years ago.

[skinny z]

This is true.
I have more sim files that only change a single component, cams mostly at this stage, and seeing the trends is certainly enlightening. It's a far cry from my first few engine builds that were all cut and try hard parts. Very few test instruments available then let alone a $1000 spark plug! Information was very lacking too seeing that the internet was still more than a couple of decades into the future.
I did have excellent tech college teachers though and their guidance produced what I'll say was definitely an overachiever in the SBC's of the day. The day being the late 70's when street racing was more of a thing that what the Fast and the Furious mangled it into.

It's the "recipe" I'm looking to move away from. At least the recipe that's gotten me to this point. That was all well and good when twenty years ago the result produced something that was above average (that would be round two of my hotrodding).
But times have changed and it's time to step it up. This is why I'm here at ST.
Thanks again.

[SchmidtMotorWorks]

When you say "sim" do you mean a 1D simulation of the gas dynamics;
or something that attempts to represent observations in power output?

[skinny z]

Power output. Simple engine modelling programs.
That said, how would describe Performance Trends Engine Analyzer Pro? Or EngMod4T? I classify those as engine simulation software.

[SchmidtMotorWorks]

They had Performance Trends Engine Analyzer Pro at Edelbrock, I didn't care for it.
I have Dynomation at home and enjoy that when I just want to rough something in.
I have used EngMod4T when I wanted to have more granular input and output.

The key to gaining understanding from the 1D sims is paying attention to the gas dynamics that accomplish the performance goals, and the tuning that accomplishes gas dynamic goals separately.

[skinny z]

SchmidtMotorWorks wrote:
> They had Performance Trends Engine Analyzer Pro at Edelbrock, I didn't care
> for it.
> I have Dynomation at home and enjoy that when I just want to rough
> something in.
> I have used EngMod4T when I wanted to have more granular input and output.
>
> The key to gaining understanding from the 1D sims is paying attention to
> the gas dynamics that accomplish the performance goals, and the tuning that
> accomplishes gas dynamic goals separately.

While I do have an engineering background (despite being a tradesman as a vocation) the concept of gas dynamics isn't one that I necessarily have used in any engine simulation situation. Reading more about EngMod4T I see that it is heavily associated with that branch of mechanics. Same with Dynomation as near as I can tell.
I'm not sure how much of an investment I need to make in upgrading any software as it's entirely likely that this engine may be the last or next to last that I intend to develop. The development for this one, cam spec notwithstanding, is all but done as I'm re-assembling what went south on the last build. With a few improvements and fortifications along the way.
After that, I hope my time is spent racing and driving.

The conversation has been great and thanks for indulging an enthusiast.

[vannik]

1. Calculator
This is a program where you give it some inputs which it plugs into a formula or a number of formulas and it gives you some output. Whether the formula was obtained from physics (semi-empirical), based on some manipulation of data or plain sucked from a thumb, it is just a calculator with limitations defined by its creator.

2. Expert System
This is a program that uses a data base of existing data, whether measured or obtained through other means, where the user gives it some inputs and the software use these inputs to query the data base in a specific way (method) and it gives you an answer. These can get very complex, depending on the type of database it is based on and the types of queries it generates while narrowing down on an answer. (The medical field is moving this way for diagnostics, almost negating the doctor). Obviously the correct answer is heavily dependent on the accuracy and completeness of the data base. And the data base is supplied with the software.

3. Simulation Software
The software is based on physics with some simplifying assumptions. i) We can do a full 3D simulation of an engine and calculate turbulence down to the micro scale. The run on a super computer will probably take a month or more. ii) Or we can model turbulence and the 3D run will take about a day. iii) Or we can approximate ducts as 1D tubes with special techniques to take area change into consideration and model boxes, plenums and chambers as 0D volumes with special techniques to simulate its spacial dependencies. iv) Or we can decide to ignore the wave action in the ducts and end up with a 0D filling and emptying model.