I’m done with whp dyno’s . I think they’re great tools for tuning but I don’t think you can rely on them for real numbers. I’ve been on three different types of dyno’s over the years from a mustang to dynojet and most recently dynapack and none have ever been close to each other’s numbers and none coincide with my fly wheel hp. Does anyone else feel the same or is this just my imagination?

 

a dyno can read whatever you want it to.

Dynojets, mustang dynos, and dynapacks are all different, and they have different variables you can mess with to produce power numbers. For instance, if you input the wrong vehicle weight on a mustang dyno, you end up with inaccurate figures.

If you went to three dynojets and used the same correction factor, your numbers should be pretty consistent.

 

Can you post the numbers and the ambient temps and pressures for the different sets of figures?

 

Any dyno which calculates your hp curve from a ~10 second power run will give you some numbers which represent (within the margin of how that chassis dyno is calibrated and operated) the power curve of your engine for that 10 second run - this is NOT the same as the power curve which Porsche publishes for your stock engine. The Porsche curve is an engine dyno plot of holding the engine under load for a time (unknown but likely to be <10s) at each rpm plot point and measuring the torque, repeating every 250rpm and then joining the dots. For Porsche to achieve this requires a sophisticated test facility which can maintain constant conditions for every test.

I am shortly going to test my 993tt on the Maha facility at Manthey Racing where I understand the testing is more thorough with the engine being loaded for such a time period which requires removal of the rear bumper to prevent it melting. I have a "Porsche accurate" engine dyno plot for my engine so will be able to compare how good the Maha is......

The pathetic thing is, whilst a few people (mainly Rlers ) want to know REAL power numbers, most people just want a high figure to reflect their manhood - I believe the Maha facility at AMS went out of business ? Is this because it was it was too accurate ?

 

I saw a picture of a TT on the dyno when UMW mapped their Stage 2 software. The rear bumper was off and the turbos and a good part of the exhaust was glowing a pretty bright red. I don't have it, but maybe Kevin has the picture.

Greg H.

 

Some good stuff on this subject here:
http://www.factorypro.com/dyno/true1.html
Its for bikes but still pretty relevant

 

biiig-hp

Short of testing on very expensive equipment, the only and most accurate dyno is a datalog of one of your runs as recorded on an AX22 or similar. We can calculate with great precision torque and HP through the RPMs and draw a dyno curve, it takes only a few minutes.

TB, this is great. You, Phelix and MOD should all strap your cars on the dyno, you can get a lot of data from it. They have special tires at Manthey for high HP cars when they are put on the dyno, Michelin Sport Cups are known to have blown up on their rollers and they might think your engine is stock. Have fun there.

 

If TB hasn't broken the dyno and MR has the time I might just have a go...

My dyno curve should fit handily under his!

 

I reflect on my manhood frequently as my wife puts it in her purse to leave each morning. Today she said I could go to Daytona instead of to the Ballet as planned for next weekend. For what it is worth there are some really sophisticated machinery in my neck of the woods and with the right connections I can get my car onto the dyno used to tune each Viper Competition Coupe before it is delivered and I will compare it to my tuner's dynapack and report back. I am running 553RWHP @.9bar I hope to have the car at Daytona as well.

 

In my opinion, in general, dynos are just good for measuring progress for particular mods, using the same exact dyno every time. Once you introduce a second dyno - all comparison is out the window. IMO you can't rely on the actual number so much as rely on the comparative numbers between your two visits to the same place.

Brandon

 

I have this pet theory that standard temp and pressure corrections should not be applied to 993tt engines because the Motronic does that automagically. So operate a chassis dyno on a stormy day or at altitude and the correction factors make the engine seem super powerful. Manthey is at about 500m so I await TB's run with interest.

 

And I could be convinced that this is a better idea than a drive to Milton Keynes.

 

The Motronic will apply the relevant tables acording to temp and pressure so the the actual power will go up or down accordingly so surely Manthey have to correct to get the DIN standard numbers

I will be interested in how they treat the IAT in respect of the CF they apply, this is the biggest variable on tt engines. They say they have effective cooling but I can't see it being good enough to replicate 200kph road airflow (a 4th gear dyno run).

RS have a proprietry method for coming to a meaningful CF which involves their water cooled I/C and lots of practice

 

My thinking (which I'm quite happy to have corrected) is that a MAF-equipped 993tt engine on boost makes very similar power at 0 meters above sea level as it does at 1500 meters because the motronic tries to achieve a given air mass going through the engine, at least until the turbos reach their efficiency threshold. So applying the DIN correction for air pressure would make the same engine look more powerful at 1500m than at 0m.

Discuss!

As an aside playing around with a PST I found that the ECU must have a barometric sensor inside of it as it knows the ambient air pressure?

 

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