Dyno results before & after tune up.

[Ross Nicol]

Pre tuning run is in red and post tune is in blue. Max power is 225kw or 300hp at the wheels, and you can see I gained 15kw or 20hp after the tune. [image]www.abbeysound.com.au/dyno.jpg[/image]

Stock 302 HO block bored 20 thou, external balance
GT40x heads match ported
B303 cam
Yella Terra Street roller rockers
8 throttle body manifold with Motec M48 injection.
Ross

 

[Ross Nicol]

 

[Ron Earp]

Re: Dyno results before & after tune up.

Ross, something is wrong with those dyno plots. Hp and torque are equal at 5225 RPM, not at 36XX? something RPM.

However, looking at the plots it would work correctly if RPM is on the right axis, which appears to be the case instead of on the bottom as indicated. On the right torque and hp are equal at 5225 RPM.

 

[roaldin]

Right side is tractive effort (flatter curves) expressed in Newtons.
Left side is power (steeper curves) expressed in KiloWatts.
Bottom is road speed expressed in KPH. Ross (or someone has given calculated rev's).
The crossing of the curves doesn't mean anything because they are being measured on different scales.
Torque hasn't been calculated on this graph.

Tim.

 

[Ron Earp]

Re: Dyno results before & after tune up.

That might explain it, but it sure as heck looks like a torque and power curve, particularily how the how the two cross. Just not used to looking at these at all.

 

[roaldin]

Re: Dyno results before & after tune up.

Excuse the misplaced ")", it was around 3.30AM here after all. /ubbthreads/images/graemlins/smile.gif
Using the same scale, ft-lb/BHP should cross at 5252 rpm and NM/KW cross at 9550 rpm.
As you'd be aware, tractive effort (N{ewtons} in this case) is just a measurement of force applied to the rollers. Torque needs to be calculated from that with reference to wheel diameter or back calculated from the power curve.

Tim.

 

Ross,

Great numbers specialy on the Dynamics Dyno (which is more conservative than the Dynojet numbers). You have the same heads and Cam as my old engine (but much better numbers). I am curious about few things,,what kind of transaxel, exhaust and rear wheels are you running?!

Thanks again for posting CHASSIS DYNO results.

 

[Ross Nicol]

Faili F
I thought you would be interested in my dyno results considering the spec is close to your old motor. In answer to your questions 1/ Transaxle ZF M1
2/ Exhaust 1.75" primary into 3" collector crossover.Straight through mufflers.
3/ Rear wheels 17" by 11" 3 piece and fairly light with 645mm diameter inc tyre.
Other features- Dry Sump with windage tray, motor /clutch fully balanced,billet distributor with hall sensors for ref and sync. Remember I had the valve seats re cut.Anyway these heads can give decent power.I'm racing this weekend with 20 extra horses and much better acceleration curve whoopee.
Ross

 

Ross, good luck on the track. It seems you realy have a good setup. If you do happen to drag the car, I would love to know what results you get with the combination you have.

Good of you to Chassis Dyno the car. IMHO, flywheel HP numbers don't belong in this section. They should be in the BS section /ubbthreads/images/graemlins/shocked.gif

 

[Ross Nicol]

Faili F
I did a 12.56sec last year at the Geelong speed trials( quarter mile with a kink)beat a heap of cobras and 2 rival RF forties.Won the trophy. I would say with 20 more HP and better tune I may break into 11's.I'll try in november.I reckon you would have got that FMS motor to perform if you had stuck with it but good luck with your next one.I don't believe a lot of engine HP figures but the consensus here in OZ is approx 33% loss in drivetrain and the experienced Dyno operator reckons I have 400HP at the flywheel. I am quite happy like you to Qute the real rear wheel figure.
Ross

 

[Trevor Booth]

Re: Dyno results before & after tune up.

You cant measure horsepower.("torque needs to be calculated from the power curve") HP is calculated from RPM and torque. This is one of the reasons why chassis dynos produce such varying results. They are a good tuning tool but serve no other purpose and no accurate conclusions can be drawn relative to engine HP. If you really want to know what your engine is doing, put it on an engine dyno.

 

[roaldin]

Trevor,

I agree with your sentiments re' chassis dyno' usefulness and purpose.
I'm sure you understood I was talking about how to get a torque (NM) figure from the graph presented. There was a misunderstanding about what was being shown on it. /ubbthreads/images/graemlins/smile.gif


Power can be described as "How far can you move something against a resisting force (in Watts example gravity) in how much time" (Watts) (sticking to metric for now).

Force is basically "How hard is something pushing/pulling" (Newtons).

Torque is a measurement of twisting force described using force (Newtons) and lever length (Metres).

Power doesn't need to be produced by a twisting force, eg a pony pulling a bucket up a pit (Thankyou Mr Watt).


As I understand it, a chassis dyno' measures force (N) applied to the rollers. The roller revolutions (includes time) and diameter are known or measured.
It shouldn't be hard to calculate power when you know how far you've moved something (roller rev's and size), with how much force (in this case derived from whatever means of resistance the dyno uses), in how much time.
The TE (force) graph produced by the chassis dyno' parallels the shape of the torque curve produced at the wheels and therefore in reality the torque curve has been measured (however inaccurately due to slippage etc), it just hasn't been turned in to a NM figure, this can be done with a measurement of the wheel diameter.

Tim.

 

[Ross Nicol]

Trevor
Your statement "you can't measure horsepower" has got me confused. If this is true then why does the scale on the left hand side of my Dyno sheet show kilowatts, which can easily be converted to horsepower, as there are 746 watts in 1 horsepower.Did you mean you can't measure horsepower "accurately" on a chassis dyno. Now that statement I could live with as many variables seem to exist and your statement about them being a useful tuning tool would I assume, allude to the dyno being capable of relative measurement only.Finally whats the point in knowing what your engines doing if no one can decide what the drivetrain losses are? I'll just go back to my chassis dyno result and say after tuning I got an increase of 15 Kw at the rear wheels and as long as the result was from the same dyno I'm Happy. I'm not going to take my engine out each time I tune it to Dyno either.
Ross

 

[Ron Earp]

Re: Dyno results before & after tune up.

I like chassis dynos. Use the same one, test and tune your car, and you've got some results you can compare. You could do the same on engine dynos, true, but as Ross says, nobody is going to be pulling engines out everytime they swap an intake manifold to see if it did any good.

Stick with one type of dyno and you'll be okay. While different makes of dynos read vastly different, I've found that the same makes, at least in my area, are within 1.5%. We, that is a collective group of us intersted in this, tried the three Dynojets in my immediate area with the same car on the same day and the results were very consistent. It wasn't my car, but I checked them over and was happy.

 

[roaldin]

Re: Dyno results before & after tune up.

I should add that one needs to remember that the engine torque is being multiplied by the diff' and multiplied or divided by the gearbox (depending upon the ratio) so the torque figure produced at the wheels reflects that.

As most chassis dyno' operators in my experience don't measure wheel diameter etc, torque figures given are pretty meaningless, although the shape of the curve is useful.

Tim.

 

[roaldin]

Re: Dyno results before & after tune up.

Re last paragraph of my post 41367.

Another way of thinking about this is to imagine that the roller is the flywheel of an engine.
The torque at the roller/flywheel IS being measured by whatever mechanism the dyno' uses because the roller/flywheel diameter is known and therefore the lever length is known (radius) (I assume that tractive effort is calculated from this within the dyno). As torque is power X revs power is easily calculated.
The power and torque of the "roller/flywheel" are now known.
Now turn it back into a wheel driven roller.
To determine the torque at the wheel that's driving the roller you need to know the ratio between the wheel and the roller.
The power figure stays the same because the same amount of work is being done, ie due to this ratio the torque figure may for instance increase but rpm must then decrease or vice versa.
This means that the power figures should be more reliable than the torque figures, especially when the ratio is never accurately calculated.

Once again remember that gear and diff' ratio's multiply the torque at the wheels.

Tim.

 

Ross,

12.56,,that is great with 20 more rear wheel HP, same car same driver, I am sure you will do better. I think I pulled the trigger to quick on my old FMS. we will see how the new one from BAD ASS does.

IMHO, as for the numbers and the calculations,,,"WHAT EVER" /ubbthreads/images/graemlins/shocked.gif,,,,,,,, Engine Dyno = BS

Chassis Dyno, Drag strip numbers = bragging rights /ubbthreads/images/graemlins/wink.gif

 

[roaldin]

Re: Dyno results before & after tune up.

Faili,

I guess that means shutup Tim etc. /ubbthreads/images/graemlins/blush.gif
In an effort to rebuild our relationship I'll state that I have just watched a video about Panteras and note that it was claimed that the fastest 1/4 mile a Pantera has done is in the 9's! A long way to go for we GT40 representatives...
Was that more interesting? /ubbthreads/images/graemlins/wink.gif

Tim.

 

[roaldin]

Re: Dyno results before & after tune up.

Stupid mistake in my post 41376 above. It should read "power is torque X rev's" not "torque is power X rev's". Can't edit it, too late apparently. /ubbthreads/images/graemlins/blush.gif

Tim.

 

[Ron Earp]

Re: Dyno results before & after tune up.

What is more interesting is checking out a Pantera dyno day in Texas last year. Not one, that wasn't seriously tricked out, was able to break 300 rear wheel. Meanwhile, lots of 5.0Ls and turbo fours were able to bust 300 on that day - and the tire diameters etc. were taken into account on this Dynojet dyno session. 351Cs in Panteras can make power but were heniously out of match with heads/intake/cam from the factory in America.

Now back to topic.