VAP

And I don't want to sound like sour grapes because thats not my intent. But after MrD explained the situation to me of them stripping a bolt to set the dyno up for all wheel drive (or stripped during the initial pulls) I think that the runs are at the very least suspect. Another thing that puzzles me is how any car can run higher numbers on it's third pull with no cool-down time after being heat soaked on it's first and second runs. It doesn't work that way for turbo cars and it's not that way for NA cars. And that's not the way his "before" dyno run behaved; strongest run was first run, medium run was his 2nd and the third run was his least favorable numbers-wise. If this were the nature of dynos shouldn't dyno operators give you 2 free pulls so the third pull would allow you to know what your HP/torque "really" is!?! Cars run better/stronger when up to normal operating temp and only for a brief window of opportunity when pushed all out before backing down on power. This car did just the opposite, it started gaining power as it got hotter and on subsequent pulls. That just defies the laws of internal combustion engines for several, if not many reasons. Back in my V8/rear wheel drive days the way to squeeze the most power from a dyno run was to install a 160 degree thermostat and take the first pull as gospel.

Another matter is the difference in ambient temps between the before/after pulls. On my UrS4 doing subsequent pulls in the a.m. at 55F and afternoon pulls at 71F the difference was 434.5HP in the morning and 395.5HP 4 hours later when it was 19F warmer out in the dyno bay. A difference of 8+%HP with no other changes than ambient temp. Add 8% to his peak HP and it immediately becomes a much more palatable number (not that 8% is the actual number one would but you can bet there's SOME percentage lost). 20 degrees differential is a MAJOR influence! Just that factor alone could've been the deduction of an additional 8HP but then what was that damn dyno doing giving higher numbers after a two-run pull!?! That is the question!

If the Stage 2+ TB is only worth 8HP with MAF inlet something HAS to be wrong. If it's true it takes 7-10 HP increase before it's even physically discernable then then that lends itself to yessrdays runs being skewed too. Cuz this TB is easily feelable, perceptable and I don't think an 8HP increase would net the kind of 0-60 increases that I and others have felt off the TB and MAF inlet not to mention just the improved response and power when cruising along at city street speeds.

I've got a strong hunch the next time MrD goes in for his follow-up dyno run with the dyno repaired and MAF inlet removed he's going to suddenly find another 8 or so HP with the MAF inlet removed and thats going to wave a pretty loud red flag to me. I've advised him that if that event materializes he should ask for a "re-do" at no charge of the original run he made today. How can a dyno with a stripped bolt that was stripped when setting the dyno up or during the first runs be relied upon as providing valid numbers when it breaks before he can make his second run!?! And when did they discover it? And if they were afraid it was going to fall into the dyno were they *****-footing it? Why would they not be afraid of the stripped bolt on the first three runs but too afraid to run the next three runs? At the very least this renders the first runs suspect. Besides I think it's just good business when dyno fails on your time and you can't complete the runs you have an appointment for that you should be allowed a "make-over" just on confidence of the first run.

I appreciate all the time and effort MrD has put into this. Donating his car for the effort and his time and money at a time he can least afford to do this. And if it turns out the TB is only worth net 8HP +or- so be it. But I don't know how anyone can or would want to be able to afford one for 8HP. I wouldn't! And anyone that owns one of these could certainly get a refund from me of their purchase price at any time, including dyno runs and shipping and costs of purchasing spare TB's to modify. And I don't believe there's a soul out there that wants that, but the offer's open. And if this TB were only delivering 8HP peak improvement I think there'd be about 7 or 8 lined up for a refund. And if I'd paid the $600 buy-in on one of these I'd be the first in that line. But there is a "feel", a perception, a lapsed-time speed-to-distance perception that this thing is better than just an 8HP peak improvement. And it really isnt all that subtle.

I'm anxious to see the next run. I'm anxious to see any run in similar temps, or close as possible on a dyno that wasn't compromised or rendered suspect on initial setup or runs, so much so that it couldn't complete a fourth pull. I'd say they owed me a complete "re-do" from get-go as this pul was specifically done to test a before/after run with the MAF inlet in/out. When I set an appointment, pay for 2 runs to test any A/B modification done while the car is on the dyno I shouldn't have to come back days or a week later to complete that comparison on yet another dyno pull with all the variables at stake. Defeats the purpose entirely.

scott12v@pghaudi

that even the same car on the same dyno with no new modifications can have very different results if run on different days. In addition to the temperature change, a few PSI of air out of the tires can make a difference of several HP.

I personally think that 10HP for a TB (even a beautifully ported one) and a velocity stack is pretty impressive. That is much more than I would have expected if I hadn't heard your seat of the pants impressions and increase in 0 to 60 times. I do agree that if your 0-60 times are accurate, Mr. D should have seen a bigger increase.

The best way to do dyno testing is to do your before and after runs on the same day within a few hours of each other, but that is often very impractical and expensive.

Nice Work!

Scott

VAP

should have been eager to voluntarily and without MrD asking to offer him a second two-run appointment at a later date for the purpose intended: to test an A/B situation on a before/after modification on the same day with a short cool-down in between runs. Not to accept the first numbers when the dyno just trouser-chili'd it's pants mid-test. Who wants to accept any number from a dyno that broke right in the middle of "A" test only to be told to return another day for the conclusion of the "B" test? They should be back-to-back, interrupted only by a 30 minute to an hour cool-down time and no more.

Mathematically I'd need to see almost a 12-15HP increase to have something to reconcile my 0-60 times against.

If it's 8HP I'll be fine with that but the experiment we were working on has been compromised twofold; by breaking in the middle of the experiment which renders it's first pull suspect and then staggering the days in which the tests will be performed which will lead to further speculation, questions, suspicions and some cynicism. It renders the entire purpose-planned experiment unequal and inconclusive.

Mr.D-'97 A4q 12v

I can get a free set of dyno runs. I hear he's reasonable and will probably understand.

Also, I'll try to make the appointment in the morning this time when the temps will be a little cooler.

By the way, I removed the MAF screen last night and I could not get the new MAF inlet velocity stack out of the airbox lid! That sucker was in there tight. Any suggestions on how to remove it?

VAP

or with a regular hammer with something soft like a piece of wood between the VS and the hammer to protect the aluminum.

Did it seem that tight going in? If not and you negotiate a "re-do" on the dyno you may want to get it out tonight and run first without it, then re-install it for the second pull.

Still strange it would be so stubborn coming out if it weren't thet difficult going in. Weird.