Petza914

I know that's the theory, but my personal experience says that's not 100% accurate. I bet this car does a better dyno run at 50 degrees with low humidity even at the same shop and why the area under and the shape of the curve is more important than the absolute number.

Speedtoys

Agreed. I get this line of argument at the track during compliance checks every other weekend..dog don't hunt.

Most of the variables in day to day differences on the same dyno with the same car are between the air filter and the piston face, no two days in a row will be the same. I commonly see the same car run a 10Hp difference between morning and afternoon on the same day. But given all that can change you can understand the range you test within. I've got spec-racing mid-pack people that podium every year because they understand that, and NEVER get DQd over HP numbers, and most of the front earns 2-3 DQs a season. Can't drop a DQ in the end season points total...they just wanna argue physics they can't control, and loose focus on what they can.

Be mindful, that a Dynojet style reading, is heavily influenced by tire position, pressure, and stiffness (construction). We have very specific protocols for compliance runs.

ptuomov

The correction factors don’t really work perfectly except for normally aspirated engines that are not knock limited (silly low compression and/or high octane fuel). In the other extreme, if you take a turbo street car to high altitude on a cold day, you can make it make all sorts of “corrected” dyno power on pump gas that it could never make on a hot day at sea level.

Because of this, production cars are now rated in environmental conditions that have to be within a narrow window of the values in the standard.

Speedtoys

True, but spec class racing doesn't do those things, its people that tune FAR away from knock.

When you get into the 'complex' setups, we just do weight/power. That day you made XXX Hp, so your weight should be YYYY or higher. With ECUs that can do fun and interesting things, we have a package we can place on a car in grid randomly that datalogs position, acceleration, etc...to see if an after race dyno reading is ..sensible to how the car performed on the track. It's all we can do to manage the "Hold brake down, flip the high beam switch three times" map shifting stuff. Some classes have spec ECU packages, but..that starts to inflate costs a lot, and get away from the point of club racing.

SwayBar

Mark Kibort has probably Dyno'd his car more than anyone else, and I can tell you that he would vehemently disagree with you, and has all the dyno runs/sheets to back it up.

On his Green Bay stroker alone, which he has dyno'd at least once a year over the past 10+ years, on different dynos in different cites, the delta amongst them all is exactly 1 rwhp. That's quite an amazing record.

So instead of substantiating your claim with a fictitious 'bet' that anyone can make and therefore 'justify' any argument, instead, go ahead and dyno your car on a bunch of different Dynojets and under differing environmental conditions, and then show us the resultant sheets. And of course that's all dependent upon your engine remaining in the same condition as Mark's has been after 10+ racing seasons.

Speedtoys

And it takes an extremely well managed car to be THAT tight over a period of time..and Mark would do that too.

Beater E30 dont often get the electrical attention a 928 demands, to run right, and I see the results.

SwayBar

Wow, you guys have your hands full trying to keep track of all of that!

ptuomov

In terms of policing, I wonder if you could pick up the ignition timing from the plug wires and some position sensor. For normally aspirated engines, the dyno correction factors are pretty good _provided that ignition timing doesn’t change_. If you get knock retard because of for example higher air pressure at lower altitudes, the dyno correction factors get screwed up.

Try correcting a consistent power reading on a dyno from a modern M5 and you’ll never get the same reading if any of the engine temperatures is different. It’ll give more boost and more advance automatically when the engine is at the optimal operating temperature.

Speedtoys

Lap times in class and history tell us where outliers are...so the cheaters being 'smart' do the hard work for us. And when you go to the data..when we have to (rare), driver is all cornering, but point A to B, is all motor, and it's here where being crafty stands out like a sore thumb.

Speedtoys

At that National Championship level..if the data gathered "doesnt make sense" then it's simply taking possession of the ECU and go from there. This is really rare..like I said, the people that wanna be crafty stand out and cause their own problems.

Some of the older spec classes were real fun, everyone just drew the ECU they were gonna use from a box. Solved a lot of problems real quick...but that's much harder to do now, than it was 15yrs ago.

The RX7 "Ok, everyone turn in your carbs for a swap" days were fun too.

But the thing is..it's never the leaders with ECUs and tricks and such, being a problem. It's mid pack people or farther back, or on the dyno where its a strict HP limit, the guy that's consistently on the podium and never getting busted, is WAY under the limit...

Regionally, a lot gets unseen purposefully, nobody likes a teardown of an inspection deeper than some inspection tamper tape or a review of FPRs just for a $12 trophy on a weekend. Show up where real money flows, and you find what regions are more or less on top of messaging.

The most passive aggressive National level inspection request I ever saw, was one line. Piston #2 pin.

If it's visible, it's reviewable..no need for a long list with that.

Speedtoys

First, yes, SPec E46, we limit them to NO more than 3 runs on the dyno, or they get hot enough to affect the mapping..even old E30s will drop a TON of Hp over a coolant temp of 185d.

The OBD2 cars where its only a stock ECU, we capture timing on the dyno with a OBD reader, and now and then someones car just _wont_ connect on the port..shake a finger, make a logbook entry that it must work or DQ in the future, and then a race later they fall back 3-4 places consistently..*shrug*.