SF Sizes

[jfholm]

If I walk in, fire up the bench with a head on it, everything stone cold & run a test, then test the same port again after the bench is warmed up good, the numbers drop about 3 CFM. They will remain there though. I've gotten accustomed to letting the bench run with the head on it, one motor running with valve at max lift for several minutes, then do my testing.

If I do it that way, the numbers repeat. If I compare stone cold numbers to warmed up numbers, the cold numbers are always a few CFM higher. I don't know the specifics of how the averaging affects that. I haven't messed around with that feature since I calibrated the bench a few years ago.

I use a test plate on top of the test stand to verify the bench very frequently.

In the back of my mind I think the manual for my Performance Trends states to warm it up, run the bench for a while before testing with the Black Box. Either that or maybe Kevin at Perf Trends told me that when I was talking to him. I will see if I can find out.

John

[larrycavan]

I don't view it as a flaw of the DM. It's a good, reliable, repeatable device. As was my FP1. As I expect are the other similar units.

This engine building, flow bench, dyno stuff is really strange sometimes. I think people want more from devices than is reasonable to expect. Comparing device readings can be such a meaningless wild goose chase if you're not really understanding of certain aspects. Hell, it even crosses over into the software side of things.

I got a couple of dyno run feed back results from another builder that I port heads for. Really nice improvements in performance after everything is all said and done. Then I sit down with various software and try to analyze numbers, predictions, etc. I don't know about anyone else but I've gotten so I take all this wonderful technology we have at our finger tips with a grain of salt anymore.

After some normal modifications, a bit more cam, a little bore increase, porting and even with stock carburetors that are 8mm smaller than the intake valves themselves, a healthy 28 rwhp was produced on a Superflow Chassis Dyno.

Add another 90cc to a similar motor, tad more cam, more head, fuel injection and keeping the stock air box on the bike....Add another 20HP on top of the first one... Quite pleased!

Then sit down with the software and try to cross correlate expectations to real results..... Things don't line up like the math behind the software indicates it might but there's no denying the significant increase in performance from the effort.....

Mind you.... the majority of engines I build and / or port heads for must meet some pretty strict criteria. They cannot loose their civility along the way. Hell, building for all out power, every time would be easy compared to trying to make more power while keeping a good idle, good drive ability, pass emissions tests in some states....etc.

People want more power but they want everything as smooth as stock to boot

Then you get the other side of the coin that guys like Chad face. Racers who want to purchase bulk CFM and demand that every CFM gain produce ET results.... Sure...what's the rest of the setup you're ignoring that will allow that with the new heads? Nobody has an easy go of it all the time.

Just another day...

[Brucepts]

I don't view it as a flaw of the DM. It's a good, reliable, repeatable device. As was my FP1. As I expect are the other similar units.

This engine building, flow bench, dyno stuff is really strange sometimes. I think people want more from devices than is reasonable to expect. Comparing device readings can be such a meaningless wild goose chase if you're not really understanding of certain aspects. Hell, it even crosses over into the software side of things.

Just another day...

I was trying to point this out just said it differently as a "Corporate Spokesman". I should have stated it in more of a manner as you did Larry.

[jfholm]

I don't view it as a flaw of the DM. It's a good, reliable, repeatable device. As was my FP1. As I expect are the other similar units.

This engine building, flow bench, dyno stuff is really strange sometimes. I think people want more from devices than is reasonable to expect. Comparing device readings can be such a meaningless wild goose chase if you're not really understanding of certain aspects. Hell, it even crosses over into the software side of things.

Just another day...

I was trying to point this out just said it differently as a "Corporate Spokesman". I should have stated it in more of a manner as you did Larry.

AMEN!

[Chad Speier]

All of my grief has kind of slowed down! The reason is, I don't take any shit from them!

I have a nice read on my web page called: The Flowbench Conspiracy..

The last paragraph..."Now the flowbench itself. Oh boy have I had a battle with this! All I can say is if you own a set of plates and your bench shows it to be off, FIX IT! The equipment is only as good as the operator, and the knowledge of that person."

[1960FL]

The equipment is only as good as the operator, and the knowledge of that person

The equipment is only as good as the operator, and the knowledge of that person

The equipment is only as good as the operator, and the knowledge of that person

Well said Chad, they will tell you your wrong when they do not even understand how this piece of equipment works or the math involved!


.

[Chad Speier]

The equipment is only as good as the operator, and the knowledge of that person

The equipment is only as good as the operator, and the knowledge of that person

The equipment is only as good as the operator, and the knowledge of that person

Well said Chad, they will tell you your wrong when they do not even understand how this piece of equipment works or the math involved!


Rick

The part I don't get is the numbers are right in front of them! It's black and white, and they still want to find a reason, or a excuse, or place blame, for some sort of internal wiring issue in their brain. Because math DOESN'T LIE..

I've decided to let them think what they choose and just keep on keppin on!

[larrycavan]

WOW You sure have a lot of extra cash flow to buy toys with

So when can we expect the FP, PTS, PT box comparison test results

[Chad Speier]

I sold the FP1 and put the PTSDM on the PTS bench. However, I think I help sell at least two DM's for Bruce!

I sold my old MSD bench and he put a DM on it.

[larrycavan]

Have you tried the PT box on the PTS bench ?

This ties to that situation where you tested a particular head and the flow backed up on the SF bench but didn't on the PTS bench. My hunch was cabinet design differences. This test could be an opportunity to get to the bottom of that particular situation.

I don't believe you'd have to calibrate the PT box for the PTS bench. It's not really about an exact number. It's about trend in dynamic flow conditions inside the cabinet.

For me anyway, this has nothing to do what so ever with selling anybody anything. It has everything to do with getting to the bottom of problems that have long plagued flow bench comparisons.

I don't believe for one second you need "A particular box" to acquire useful data. I do believe you need a testing environment that doesn't mislead you into reworking a port that doesn't need to be reworked

Ball's in your court