Jean

I think that looking at AFRs vs RPMs and boost is just like comparing dyno graphs with each other, they have to be looked at very directionally. The load exerced on each dyno will also have an impact on AFRs and boost vs RPMs.

To give an example, if you look at Graeme's dyno chart, you will notice that at 3500RPMs his boost was around 0.4Bar with stock KKK24s whereas TB's dyno shows around 1 Bar. I could say that RS know how to extract boost from turbos much better, but that is 1/3 rd of the story maybe, the reality is that Graeme's Dyno Dynamics run had much less load than the RS dyno, therefore boost takes much longer to build.

Those stock KKK24s should have full boost much faster than TB's large hybrids, albeit if we factor the higher CR of TB993TT, then maybe both turbos should build boost almost the same way vs RPMs. Graeme's dyno run will show higher peak numbers, howver less area under the curve. This is exactly the same phenomena I saw on my runs at Manthey, where I had much more torque downlow (much broader curve) as a result of the strong load exerced by that dyno on my engine. The AFRs on these dyno chart will follow the boost onset and torque, therefore they are also skewed and cannot be compared very meaningfully, other than seeing how high or low they go as a whole.. Out the car on the road, and it will not be seeing the same numbers at those RPMs.

My AFRs are very similar to TBs, they hover around 0.8 lambda all the way with small swings. It is timing that protects my engine by being pulled back after setting the AFRs where the tuner wants (or can). By going with richer AFRs the tuner has more flexibility with his tuning to remain wihtin safer grounds. This comes at the expense of potentially better performance.

I must say that Todd calibrated my engine rich per my request to protect against heat on the track in the high temps we have here, it seems to have paid off in reliability. He later dialled the mixture a bit leaner than what my engine dyno showed, both at idle and WOT after he did the road calibration in Germany

TB993tt

Jean, of course you are 100% right about the dyno loading variations, affecting boost levels and so lambda also - but isn't this the to the crux of what Stummel is saying ?
Tuning a 993GT2 on a low loading chassis dyno using 9 second power run sweeps to confirm mixture and boost levels is pure amateur and unbecoming for such a car......IMO

graeme36s

I don't really have the option of taking the car to RS or Manthey in Germany and I am confident that Fearnsport can sort it out. The mapping was actually done on the road. I can't say if they mapped it whilst driving as I was not there and I have no idea if it can be done this way. But it was driven and checked on the road.

JBL930

So what you are saying Jean is that the dyno run is completely worthless in reality, the engine isn't under as much load as it would be pushing the car along the road, air resistance/weight etc. So his engine doesn't doesn't build boost as it would normally, therefore the relationship between RPM, Boost, AFR etc on the graphs is all askew.
Is there anyone in the UK with an engine dyno that can tune motronic properly, or do we have to go to Germany for that?

You mentioned your AFR's and said you hover around 0.80, does your car ever get as lean as 0.90 like Toby's? I'm not for one second questioning Toby's numbers, i'm just intrigued. As i mentioned before i melted a piston whilst my engine (granted it was only taking readings from a single sensor after the turbo) was definitely under 0.84! I guess i must have had a dodgy injector on that cylinder, or the 930 engine has to be a lot richer than a 993 to stay alive, either way it's now gone over my head

Jean

I did not say it is completely worthless, I am sure a rolling road helps you calibrate a lot of paramaters to get you almost there, however without a properly loaded run that would simulate real full WOT driving conditions you will not get the right calibration.. Any tune-up without a final road calibration is less than perfect, and that includes RS Tuning despite their state of the art engine dyno. As an example, they did not accept to build my engine unless the whole car was shipped to them.

I am sure there are quite a few (good engine or chassis dynos). Give Richard Chamberlain a call, he will put you in the right direction. As to Motronic tuners, I know a few but they are all in Germany and Belgium or France.

I get very close to 0.9 at sub 2.5-3k RPMs, there is no risk whatsoever there, you're off boost and 0.9 is still not lean.

JBL930

I guess the statement "completely worthless" was a bit strong, there doesn't seem to be a lot of info on those graphs that you can actually rely on though does there. I've used that dyno when it was called GForce, as well as the one at Silverstone when Weltmeister was in business, also the old Maha one at Bob Wastsons, and of course the comedy one at Ninemeister. The GForce and Weltmeister Dynodynamics cells were by far the most professional installations, plenty of cooling etc, it's a real shame they don't load the engine properly

Jean, i'm sure you do get close to 0.90 off boost, but do you go over 0.80 on boost and up to the red line?

NineMeister

You're welcome to your opinion Jon. However as the owner of the only chassis dyno facility in the country that has a dedicated aircooled 911 dyno installation with 70mph cooling air feed above the engine and hot air extraction directly below the engine, I would prefer to think that Ninemeister are the only people taking this seriously, we don't laugh about tuning 911's.

I totally appreciate Jean's and Toby's points about relative accuracy between diferent makes of chassis dynos (and engine dynos for that matter - even different engine dynos give different results) so as a policy I chose to only make comparisons between measured runs on our own dyno but what customers do with the data we get is their choice. We may be measuring Ju-Ju beans for all I care - the thing that really matters is that the engine has more of them after we have tuned it, is faster as a result and does not melt down in the process.

No more to add, all the best.

JBL930

Ju-Ju Beans is a good one Colin, it's certainly more believable. Don't know if you've read GTPorsche magazine this month (March edition) the chap with the RS blue GT2, there is a comment at the top of page 95 that goes like this "when you're running over 550bhp and a massive Ninemeister dyno-certified, 587ib ft of torque" I had a chuckle Colin, the dyno-certified bit must have made you cringe?

Another thing, are you saying you've never built an engine that has detonated?

TB993tt

To be fair 587lb/ft (798NM) is only "as" ridiculous as the DD chassis dynos measurement of Graemes 566lb/ft(770NM) - tuning Porsche turbos on most chassis dynos does seem to give these silly numbers it is to do with their inability to brake the rapidly escalating torque which is a feature of the turbo engines.

Remember the Manthey Maha struggles to measure much more than 750NM as a maximum, this level of real torque takes some braking:
https://rennlist.com/forums/993-turbo-forum/389143-dyno-tests.html

NineMeister

Jon - "does not melt down in the process" refers to the cooling capacity of our air management system on the dyno - in my experience the tyres usually give up long before the engine is too hot to tune. Of the turbocharged air cooled turbo engines we have tested, heat soak of the intercooler has never been a problem which is more than most can say.

As Toby rightly points out, the torque capability of an engine on a transient (chassis/inertia) dyno is completely different to that measured on a static (engine) dyno. However, since we all drive our cars in transient conditions (albeit fast transients up to 120mph, much slower above) Jean's in-car acceleration measurements can only be the true measurements of the ability of any engine to push a car down the road faster than a rival. The downside is that unless you are prepared to do a lot of work on measuring coast down losses you will not be able to calculate corrections for tyre drag, wind resistance, windspeed and atmospheric conditions, but you will know how fast your car goes.

JBL930

My bad, i thought you were referring to something else, as i know of at least one car, a 993 GT2 no less, that you fitted a fixed boost set up and it ended up with melted heads, tell me that blue one isn't on fixed boost Colin?

Jean

Colin, I fully agree with you concerning all of these parameters and their impact on performance. I think however that after having looked closely at over a couple of hundred runs and "dyno graphed" almost as many from all sorts of Porsche cars and engines, there is a certain knowledge base that was built, not 100% accurate but certainly very reliable when it comes to accuracy of engine output.

If I am not mistaken you are mentioning the above because after JBL sent me his runs right after he took delivery of his car, his performance was more like a 330-340HP car rather than close to 550 in the higher gears (3rd or 4th I believe). His torque curve as charted through his AX22 datalogs, was showing a huge drop across the gears after aerodynamic and rolling corrections that I always factor in my graphs..

I wrote back to him telling him that something was really wrong with his engine and that he should go back immediately to his builder ( I did not know who it really was since there had been some changes) to have it checked for a lean condition and not to run it hard anymore until it was sorted.

I don't know what happened after that, but I did read that his engine blew up shortly afterwards, shame is that it could have been avoided.

If he was on Motronic, he would probably have been saved by the electronics and knock sensors, but unfortunately his engine was a K Jetronic if I am not mistaken. I have seen a modified 993TT from a friend Rennlister with a very similar issue recently and also warned him about the same thing, his car is still running, surely thanks to Motronic, but his performance is not there as it should have in the higher gears, typical heat soak issue.

I am afraid that the above mentioned 800NM stock KKK24 993 GT2s would have the same fate if they didn't have all the Motronic safety nets . If you go back to the BMEP thread that I posted sometime back you will see that those numbers are impossible on stock K24s since they would need to run 1.5 bar to have a torque of 800NM.

I honestly do not wish to get involved in this customer/tuner debate, I just had to clarify what happened in all transparency. I did mention to JBL long time back that I would be happy to take his tuner through my findings if it would help him find the problem, and again, I did not know who it was (not sure until today honestly, but I am guessing through the above debate)

Cheers
Jean

JBL930

Jean, my car during those runs was indeed set up by Colin, running with a 7th injector to pump fuel in at the neck of the intercooler, it repetitively posted 497bhp and 617nm on his dyno, and under 400bhp on two others within the same month. I did forward your e-mail to Colin but TBH i'd run out of patience, also the Garrett turbo he fitted on my car had seized up AGAIN (second one in 13k miles) so i took matters into my own hands,. I bought a K27HFS, airbox, fabspeed muffler and fuel head from IA and was going to fit an adjustable WUR to dial the fuel in and I junked the 7th injector. I had an adjustable WUR in my hand on the mini Vmax day but i thought i'd do a run first with the standard one fitted and my engine went bang on the first run, my bad, IMO it shouldn't have come to that anyway, i should have had a properly tuned car in the first place, God knows i'd spent enough! Colin, your dyno is comedy, so is your approach to tuning CIS cars, I could go on but i won't, i just wish i had done the correct research before pouring money down the drain, maybe others will benefit from reading this?

JamesE

Me also...

TB993tt

I was so incensed with Colin "dissing" my RS engine and by implication me for spending so much money "pointlessly" that I actually saved the interaction which happened on Pistonheads in 2005.

Just a rumour but I heard from a couple of sources that engine which Colin refers to as "JC's" was the one which eventually melted its heads despite the superior 9M tuning methodolgy......

Here is the interaction cut and pasted from '05:

5. With respect to the difference in the mods we do compared with RS tuning, I have found that we get more power/torque out of our engines on lower boost levels purely because we run more ignition timing on a rich mixture, rather than up the boost and back off the timing on a weaker mixture.
However judging by the standard of mapping seen on a couple of German tuned 993RSR's recently, I would not be surprised if simply a more complete understanding of the management system has a greater part to play.




tb993tt said: Not wishing to start questioning 9Ms dyno numbers as that is a little tiresome, but I am fascinated as to how you GT2 guys are claiming such big numbers (compared to RS Tuning engine dyno numbers) from limited mods.



But you are clearly questioning my dyno numbers Toby, the very same dyno that I have used for 15 years with great results. The trouble is that you have shaken the tree and are now backing out of the way of the falling coconuts, so here’s one for you:

When you visited 9m earlier this year, do you not remember me offering to dyno your car for free? You have seen the cooling arrangelent on my installation and know that one test will not punish the car, so why have you not taken me up on this offer?

Is it that, possibly because of the money you have spent, you do not want to know how well your RS tuning engine compares to JC's and RG's? I am sure that given the opportunity JC would be up for sharing the same test session (at the same cost), thus putting the debate to bed once and for all.