eclou

This is exactly the point! Most of our GPS logs show cars at about .5 g max in 5th gear acceleration, but nowhere near the .9g that should be the adhesion limits of street tires. There has to be some kind of explanation as to why the problems surfaced with your's and Jean's past runs. I am inclined to lean towards set-up/procedural errors.

Acropora

Rofl, those numbers are WEAK! You need to get a new motor TB...

j/k of course. Was running down GT3's at .6 bar because the stupid IC hose was barely hanging on, at mid ohio today so yours would be a rocket.
I wonder what the 1/4 mile trap is. Interesting info TB, thanks.

911/Q45

I wonder how rough the dyno roller surface is compared to pavement? Could explain higher slippage rates on the dyno.

eclou

Most of the rollers have some kind of diamond-etch in the steel surface, and I have seen some Dynojet rollers with an abrasive (sandpaper) style surface. Most of the rollers though will get some rubber residue transfer from the tires over time. I would imagine that this "coating" could harden over time just like an old tire and lose tractive ability. As busy as Manthey probably is, I wonder if their roller surface could just use a good cleaning?

TB993tt

The limits on the rollers must be much less than the ~0.9G. Manthey dyno many Porsches and I would have thought if enough customers exceeded the limits of their dyno then they would look at changing their procedures - The way I see it is they don't see many Porsches with 770+REAL NM....

Stummel

I will ask them next time I am around.

Manthey is a very racing oriented facility with most cars being n/a with much less than 700NM torque.
There are not many Turbos/GT2 that are frequently driven on the ring.

Question comes to my mind - how did they tune their big turbo kits on that dyno???

Red9

Thanks for sharing that TB-- really interesting (again) .I have never been a big fan of dyno's in general-particularly as I have the view that they are hard on the drive train.Interesting that you monitored some essentials and they were able to keep within reasonable parameters.

eclou

I think this may be a key point - most of their race applications would be high rev low (relative) tq engines that only hit peak tq when the engines are hitting high rpms. Monsters like Toby's and Jean's may be far outside the normal realm of what they deal with. If so, I still would think that the Maha should be amenable to calibration for such applications.

Jean

Eclou,

I think it would have to do with the level of resistence these loaded runs exerce on the the tires.

As a clarification, I had brand new 315 Sport Cups when I went to Manthey prior to the track, and they had to change the wheels and tires (see TB's picture) because they have had a number of R compound tires blowing up on their dyno, this should be an indication of the level of heat and load exerted on the tires.

0.9 Gs is when you have the mass of the car shifting towards the tractive tiresupon acceleration, the front tires for instance will never withhold 0.9Gs of acceleration on a 4WD 993TT. It all has to do with mass transfer over the tires. There is a formula that can calculate the impact of weight on traction.

Manthey would not do procedural mistakes this easily on a dyno.

eclou

If they are loading to the point to cause R compound tires to fail, then could they not decrease the starting tire PSI in anticipation of the heat cycle to be encountered? I understand your point of the wt transfer being removed from the testing procedure (as would the aero downforce), but I would think the suspension could be loaded via the tie downs to compensate and improve tractive force. Perhaps even testing the car in an overdriven 6th gear to fractionally reduce the wheel torque could be tried if it did not overspin the rollers?

But alas, I apologize for digressing. Very impressive results TB!

pole position

AMS sold and the deal fell thru. It was semi open for some time but it might sold/closed for good now. It had nothing to do with the MAHA, their bred and butter was Audi/VW tuning, parts and service. Business slowed down and it became more difficult to make money or stay profitable without major headaches.

Some cars blew up on their dyno , some owners were afraid of the 45-60 sec runs and rather bragged with dynojet or Mustang sheets but they still did a lot of high hp/tq cars like tuned vipers etc which held together. I have not been there in some time and cannot remember what their top hp/tq figures were. To the best of my recollection they never put special dyno tires/rims on.

BTW, CEC/Brabus also has a Maha in SoCal but it is not open to the public as far as I know.

Jean

Eclou

The R Compound tires were found too soft to withstand the dyno runs, they had serious issues with them blowing on turbo cars. They could probably have loaded the suspension more, but they would have done it if it had been the solution, I cannot answer that though.

They do runs in 3rd, 4th and 5th gear, however their conclusive numbers are taken from the 5th gear run only, from 2K up to RPM limiter in about half a minute run,in a road-like simulated load, this is where the engine and transmission are getting hot . In lower gears the numbers were higher even with the right correction factors and still considerable load.

I think TB's objective (pls correct me if I am wrong) was not to know what is his max HP and torque, since I believe he knows what they are, but rather to validate and compare numbers vs. Manthey's as an experiment and curiosity, the exact same reason I did.

There are many higher engine outputs out there, but the interesting part is to know what one's numbers are when compared to factory-like numbers

As an aside. Manthey was the chosen Porsche Motorsports R&D partner for the 997RSR and given the first factory werks car as a result of their engineering rigor and racing reputation, they would not invest this sort of money in such a dyno facility if they did not take it very seriously. And I am not a fan of their engine upgrades, don't get me wrong .

pete95zhn

Measuring the accaleration with GPS on the road the car has to fight the resistance of air too, and @ 5th gear there's a lot of it...

sweanders

It would be interesting to run this car on a Rototest dyno.

TB993tt

Red9, Brad, thanks for saying thanks

Pole, thanks for the info on AMS....

Eclou, I am not sharing any numbers from the runs since the only actual chart they managed to get was at less than full throttle up to 6000rpm so they only actually managed to measure real power at 6770rpm !
The dyno run was technically a complete waste of time and money for the purposes of my original objective of wanting to compare my certified engine dyno sheet with a state of the art chassis dyno sheet.....

However because I am pretty sad, there is lots to be taken from the experience for me (like the Gemballa fiasco above) in the understanding of this fascinating subject. Food for thought for me is that the $150K RS Tuning 997tt engine "only" has 890NM(654lb/ft) so quite what is happening with the plethora of 700lb/ft RWTQ cars tested on dynojets and the like, will continue to pique my interest