would you like a blood and urine sample also?

 

Hi Paul,

That large a correction would be abnormal. I don't like to make any assumptions since I can't see the rest of the data. Again, I always recommend using the standard dynapack graphs rather than the comparison mode.

In order to run a car on the dyno, the operator sets the following factors:

Total gear ratio (chosen gear x final drive), selected rpm range (starting rpm and ending rpm for the run), ramp time (time in seconds to go from start to finish), settle time (number of seconds to let the car stabilize at full throttle at the start of a run), and lead in (basically how many revolutions to delay before starting measurement).

The operator may also enter vehicle weight, tire size, etc. but they have no impact on power measurement. The real key there is the ramp time. The operator may also enter a TCF (transmission correction factor) that will multiply corrected measurements by a set factor to attempt to compensate for tranny losses. Again, we don't use this and you can see if the TCF has been fudged on the standard graph screens - 1.0 means there is no multiplier.

Dynapack is always shy with their exact methodology, but basically the system works by using a hydraulic motor to exert force in opposition to the drive force of the vehicle. By precisely measuring pressure applied and rpm, the software is able to calculate power and torque - IOW, very similar to a modern hydraulic engine dyno. The primary figure measured is hub torque.

Our dyno's are constantly running. It is 7pm here now and we've had two cars on since 8am this morning. We _tuned_ over 1400 cars last year and are on pace to beat that number this year. That does not include cars we simple baselined or tested for dyno days. We just did a dyno day on Saturday where we processed through 36 Nissans in the space of about 10 hours, although we actually did 22 cars in 4 hours early in the day. I figure we could do 40 Mini's in one day if necessary.

Oh, and on the drag car, it doesn't sound like it was traction limited if it was pulling the fronts that hard. The key is traction limitations. We have a couple customers running a class called Sport FWD. They routinely make over 900 whp in a 2500 lbs chassis. Unfortunately, they are FWD with a maximum slick size of 24.5x8.5" and no traction bars allowed. Despite making all that power, they can only apply about 500 hp in first gear, 650 hp in 2nd and then full power in 3rd (sometimes) and 4th gear. They still trap at 160+ mph, but their ETs are in the mid-9 second range due to traction limitations. With that power to weight ratio, they'd be trapping at 170-180 mph if they could put all the power down.

 

So if a car shows a abnormal high mph would that be down to the tire height being wrong, though it doesn't in theory effect the horsepower / torque numbers.

Do you sometimes forget how lucky you are to have a successful business and something what you enjoy

As for the drag car we had been blowing the tires off all weekend(all year) hence the high qualifying ET.

So back to the original discussion, If I took a car down to you and dyno'd the car, then took it to the track and weighed it and run it, I would have a formula which would give me the same horsepower as your dyno showed.

I think that looking at this thread and hearing / seeing other peoples results with the same components you only should compare cars that use the same dyno. As I've aid before its the custome who expects to have the same number as the highest one acheived here on NAM, you can undrstand there logic, I've got exactly the same compnenets as Big Howe so why haven't I got 260?

Do you think you should compare Dynapack results across the world? and why would Jan quote 12-15% drivetrain loss with numbers from a dynapacks?

I still believe as stated earlier that you could dyno an engine on an engine dyno and make 200flywheel hp, 180 hub horsepower on a dynapack and 165whp on a roller dyno (numbers are just an example)

Which goes back to the drag strip, at the moment here in the UK JawF430 has proberly got the most horsepower we've seen by running 104.3 at 2850lbs where as Jove holds the world record at 105.82 but weighing in at 2488lbs all on the same day at the same track at sea level and both cars run a RMW head.

Next year has got to the year off the 12s for someone with an M45 and road tires.

 

It's very simple... you don't have the RMW less restrictive exhaust and you don't have his engine nor his methanol kit

 

So you're back to the Tuls, what day of the week the car was built theory then

 

everyone knows each car is different but the facts remain that a car that made 199whp on a dynapack went 13.8 and you said it was 250bhp

go figure

 

You still dont get it MPH MPH MPH MPH MPH MPH MPH MPH MPH

Forget the ET

Anyway so when is the first RMW Dyno Shootout at Churches, who can get there car in the top 5?

Longboard can do the grilling and you can raise some money for charity at the same time

I would of obviously rather you all go to Fontanna, but I could imagine all the excuses in the world would off followed

 

Won't be me, too far to drive

 

why you want to keep changing parameters to fit your formula is beyond me... real scientific there

I'm not sure what you guys are doing but I can tell after having tuned hundreds of MINI's not one stock headed car ever beat ones with cylinder heads NEVER

 

you need to get back to the track and pass more M3s etc

btw... give me a call I need to talk to you. Haven't heard from Larry in awhile... is he ok?

 

My stock cylinder head has beaten your heads all year apart from the last meeting when I had to actually switch the nitrous on to beat Jove.

Until you take your top dawg to the track and light the scoreboard you really have no arguement Jan.

You can theorise all day and look at pretty graphs, but go and light the scoreboard up, show us the vid and the time ticket of one of these amazing hub horsepower cars.

We all might learn something

As Jove would say Proof or STFU

Or my personal favourite is when the green light drops the BS stops

 

 

thanks for the laugher

 

None left to pass

 

surely not..........you mean those other Mini's on the track with stock cylinder heads can't pass those M3s in the straight away without a point by?

I think we all know the answer to this.... but its quite entertaining anyway

 

You still pulled the front end Paul, traction wasn't an issue on _that_ run then, was it?

And yes, I believe comparisons are best made on the same dyno.

Regarding a calculation you would have an equation for that car, on those tires, on that day, at that track, with that driver. As I stated, there are so many factors that affect trap speed that doing a best fit line is a very first order approximation of avg hp. I have been drag racing FWD cars for over 15 years (don't do it much anymore, I'm more of a road racer and FWD launches frustrate me) and have been amazed at all the different things that affect time at the strip. For example:

1) Changing the rear wheel/tires from standard road items to 4" wide skinnies. The weight reduction was only about 25 lbs total, but trap speed went from 101 to 102.5 mph.

2) Lowering slick pressure from 6 psi to 4 psi netted an improvement in 60' and ET, but dropped trap speed by 2 mph on a ~135 mph trap speed FWD car.

3) Improving a driver's shift times in a NA FWD car improved ET and MPH from 10.1@138 to 9.90@140

4) Changing the shape of the power curve by going to a bigger engine. Going from a 2.1 liter NA engine to a 2.3 liter NA engine netted a miniscule increase in top end power (about 1%), but netted a huge increase in area under the curve. Torque was up 5-7% across most of the operating range, only coming back to the smaller engine above 9000 rpm. On the track, the bigger engine returned notably quicker ETs and trap speeds. But a first order calculation would have estimated more peak power when all that changed was average power.

The problem isn't that you can't apply a calculation, its that the calculation, by nature of its simplicity and lack of variable inputs will necessarily incorporate the specifics of that car and run which may be completely different another time. Any number of non-power related items can change and cause you to estimate that power has increased when it really hasn't changed at all. If you have a fully optimized drag car where you keep non-engine parts consistent, have a good driver, and correct for weather and altitude, you might do o.k. with a first order calc, but most folks here are hardly running such a combination. I find that rough approximations are best used to estimate projected improvements or changes from a baseline for a given car only. IOW, if I run 11.0@125, and I find 20 hp, I can expect a certain improvement and can model that pretty easily because I assume so many variables. Of if I set the time at a DA of 1000' I can expect a certain decrease in performance going to 2000'. But I would be ill advised to expect another car with the same power to weight ratio but completely different setup (engine type, tires, aero, driver, etc.) to return the same trap speed.

BTW, I don't believe in luck. As a wise man once said, "Luck is an illusion, an excuse used by the weak-minded to explain their failures and by those lacking self confidence to explain their success". But I am very happy to be doing what I love - it is so much fun to work on so many different cars. Yesterday for example we had a supercharged Honda B-series, a nitrous powered Honda B-series (drag car), 2 large displacement Honda K-series (one time attack car), a supercharged Cadillac V8, a supercharged Mini, a turbocharged I6 Toyota, a supercharged Nissan V6 and a nitrous powered Honda K-series (land speed record car). Diversity rules.

 

Paul
You must be joking that your car turns better times than a car with Jan's head and all other things being egual. I've been involved in this sh*t for over 40 plus years and have never seen the same engine run better times with stock heads than the same engine with heads that were done properly. Isn't that engine 101 basics. Sounds like driver error too me.

Jan
I know of a stock head MINI that passes M3's on a regular basis. Even MINI's with heads. Damn driver error again. But that MINI wishes he had your head or a 1.8 .

Yes I'm alive. Been very sick for 2 weeks.

 

Glad to hear you are ok

 

Shawn

Traction was the issue on that run because Jeff lifted after .83 off a sec as it was going on the bumper (we're not allowed wheelie bars in the class) we tore up the chassis in 05 when it landed after a wheelie in qualifying at the World Street Race at No Problem Raceway, Baton Rouge USA. We still made it to the finals but thats another story.

Well Shawn with the above knowledge it looks like you're the missing link in the chain for Jan and his buddies as I think there missing someone who can drive down the 1/4, so with your history they have no excuses, you never know you might enjoy it more going slow.

I know with the Mini leaving at 7400 on slicks the rpm drop to 1400 and seem to take forever to come back round to 7000 again, so your above post has some good advice.

I'm sure where we are at now we could proberly go 13.0s at 104 with the stock head, we previously went 13.25 at 102.5 before being able to tune it.

I think you missed this question below;

So if a car shows a abnormal high mph would that be down to the tire height being wrong, though it doesn't in theory effect the horsepower / torque numbers.

 

newbs49

This year there is only Jove who beat me and he run a 13.2 @ 105.8, the other 3 RMW cars didnt, when you look at there times is obvious where there loosing it but I'm sure Jan has that one figured.

As a reference point the best my SMG M3 run after several attempts was 13.9 @ 100

 

Talking of laugher, what times are ya going run around button willow?

And where is Rustyboy?

 

I think you've missed my initial point Paul. If you have _insufficient_ traction trap speeds can be substantially lower. Your car had a surplus of traction.

I'm not sure exactly what you are asking? About the mph reading on a Dynapack? Yes, that would be down to incorrect input and would have no bearing on power/torque readings.

 

[quote=Paul Webster;2548421]

Do you sometimes forget how lucky you are to have a successful business and something what you enjoy

quote]

Quite the classy move Paul. Shawn Church has been nothing but polite and respectful to everyone involved. I guess we all know your true colors now.

 

you sound more like Nitro each day

 

I'm sorry to say but with Jeffs car whether we hook up spin or wheelie and get off the throtle then back on it, it runs similar mph.

If you look at our example we run in the MINI at the Euro finals in 07

Row 50 run 12.3830 @ 115.27 60ft 2.2298 Time 13.59
Row 66 run 12.5943 @ 115.34 60ft 2.4531 Time 15.10
Row 77 run 11.7722 @ 115.93 60ft 1.7991 Time 16.03

So 0.57% from the worst mph to the best mph on the same day.

http://www.eurodragster.com/timing/2...r%20Street.xls