Day On The Dyno

[Mercules]

One needs to be careful comparing results from different dyno shops.

Certainly this has piqued my interest in looking into tuning my cars this way.

Very true - i have seen the same car/same tune punch out very different figures on two different dynos. Outright horsepower figure comparison is best left to the guys down the pub - use a dyno as a compariitive tool for your car only... stay loyal to your tuner... keep it all under the same roof. That way you can be sure of how much chnaghe has been made


Cam

 

[Des]

One also needs to remember, which I don't think has been mentioned that MB would have quoted HP figures from the engine, not from the rear wheels, you loose about 30 percent of the power through the driveline from memory.

 

[Styria]

One also needs to remember, which I don't think has been mentioned that MB would have quoted HP figures from the engine, not from the rear wheels, you loose about 30 percent of the power through the driveline from memory.

I know where you're coming from Des, and that's been taken into consideration. The question that therefore remains to be answered is:

1) Why there should be so little difference between claimed and actual hp figures for Mercules' 450 SEL, and

2) Why figures for 6.9's published heretofore should to down to such an extent between 'quoted' and 'actual'.

3) Pulse Racing - and no suspicions directed in any way - is their way of testing accurate ? I know it ought tobe, but it would be interesting what readings one would come up with if another Merc 450 or even 6.9 was tested.

As I said, can't wait to get GB onto the job. Regards Styria

 

[B13]

Dyno Dynamics, who make the most commonly used unit installed in Aus workshops, recommend a regular recalibration of the system, i think its every 12 or 18 months.

Selectmaz in Melbourne, the people who built my 13B race engines, are the only place who I know regularly calibrate their dyno.... but they also only work on rotary engine cars so they aren't much use to us MB drivers.

I think the reason places dynos vary would be mainly due to lack of calibration, but also due to the fact that the use of them (to maximise power) isn't really dependent on baseline HP reading. If the tuner is able to increase power by 20HP then it doesn't really matter if they start at 140HP or 150HP etc.

In 1999 we had MB dyno day at a place in footscray and while I can't remember the specifics they figures read as follows:

my 6.9 #3904 = 168RWHP
my RX4 race car = 158RWHP
114 280E very tired 60RWHP
123 230E 95RWHP
126 560SEL 168RWHP (blowing lots of smoke)
Escort Mk2 1600cc = 48RWHP

Ian.

 

[Des]

I know where you're coming from Des, and that's been taken into consideration. The question that therefore remains to be answered is:


2) Why figures for 6.9's published heretofore should to down to such an extent between 'quoted' and 'actual'.
Regards Styria

A few ideas come to mind......

1. MB would be quoting conservative figures, factory 6.9 is supposed to do 220k's per hour, if you do that, you are not driving it on the limit, just playing it safe.

2. Remember the super car scare here in Australia in the 1970's?
I'm sure Mercedes wouldn't want any bad publicity for their new top line models.

We know these cars will do so much more than the factory quoted specs, there was a contempory road test that had a 6.9 at over 150MPH, that's fast!

 

[John S]

The 6.9's are undergeared so at 140 they are well over their peak power revs - I think that the claim of 150 mph is overoptimistic.

 

[Des]

The 6.9's are undergeared so at 140 they are well over their peak power revs - I think that the claim of 150 mph is overoptimistic.

I'll have to find the magazine article where it mentions that.

I remember over on the other forum AMG69 mentioned he had his 6.9 up to 240kph, thats 149mph on my calculator.



Can just imgine that massive engine going flat out, what a noise it would be, and how fast it would be drinking fuel

 

[Styria]

Hi JohnS. From memory, peak power is abouit 4200 rpm, which equates to in excess of 160 k's an hour.

It's probably all academic to a greater extent - however, it would be nice to know that one'sengine is operating as efficiently as possible.

Efficiency translates to a better power delivery - conversely, better power delivery equals greater fuel economy. Incidentally, what Mercules has not told us at this stage if, in fact, his 450SEL is running more economically, i.e. using less fuel. Regards Styria

 

[WGB]

I remember over on the other forum AMG69 mentioned he had his 6.9 up to 240kph, thats 149mph on my calculator.

I am sure AMG69 is far too law abiding to have considered doing that - let alone achieved it in our heavily policed roads.

Can just imgine that massive engine going flat out, what a noise it would be, and how fast it would be drinking fuel

When used with gusto I think the 6.9 motor is amazingly economical for it's size and era. The Post 1976 holden and Ford V8's of the same era (with significantly less power) were often heavier on fuel during road test reports and even worse when you actually owned and drove them. It's just that the 6.9 doesn't get a lot better when you drive it quietly.

What is doesn't have are a number of complicated electronic controls and an overdrive transmission that would make it more economical at cruise or with quiet driving.

What I find really amazing is that my 164 - 500ML has about the same overall fuel consumption of the 126 - 300SE that I owned 20 years ago and that was streaks ahead of the emissioned 280E/SE that preceded it.

Bill

 

[Des]

Dear Bill

Maybe I am thinking of someone else from WA?

unsure now




Kind Regards
Des

 

[Oversize]

Very interesting indeed! I have heard that a proper tune will not only increase power, but also reduce consumption....