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richard,

That's interesting - you have exactly the same ditch in the torque curve between 2-2500.

What would cause that?

 

 

the chap at the rolling road printed me a graph with the air fuel ratio.

where the dip is, the air/fuel ratio shot up running v rich.

in my case he suggested i needed thicker oil in the dash pots on the

SU to prevent them rising quickly when you put your foot down.

it probably is partly that, plus its the rpm where the cam starts to come on cam.

cant say i notice it when driving though.

richard

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Richard

But mine has Pi!

Though Pi could have a similar fault, to have by chance the same 'ditch' with two different fuelling systems seems unlikely.

So I fear it's not that!

 

ntc,

Thank you! Pm on way

 

John

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Richard

But mine has Pi!

Though Pi could have a similar fault, to have by chance the same 'ditch' with two different fuelling systems seems unlikely.

So I fear it's not that!

 

ntc,

Thank you! Pm on way

 

John

 

Are you both using std timing gear or vernier

Regards

Neil

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Richard

But mine has Pi!

Though Pi could have a similar fault, to have by chance the same 'ditch' with two different fuelling systems seems unlikely.

So I fear it's not that!

 

ntc,

Thank you! Pm on way

 

John

 

could it be the exhaust manifold coming on song so to speak.

std cam sprocket.

richard

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could it be the exhaust manifold coming on song so to speak.

std cam sprocket.

richard

It's all speculation, I suppose.

I have a vernier, which was useful when installing the chain, but nothing like as useful as on an engine with an open timing belt, so that you can swing the cam timing between runs, to find the sweet spot. I did fabricate a timing cover with a bolt-on access plate, but the 'access' was too poor, tight up behind the radiator, and welding in the bolts, I left pin holes on the cover, so I've not done that again!

 

John

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Some operators test them in third and some in fourth, but you have to get to third or fourth hence the gear change and the dip.

 

ncoll

 

ncoll is correct the only true way of measuring engine output is with the engine on a dyno test bed, rolling roads can only be used to adjust the engine for optimum performance for use in normal conditions. As John said the cam timing can play an important role in this but that is another issue

Edited by ntc
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Richard : I wrote something wrong : "... the misunderstanding is that someone can give away some power at high rpm to gain some torque at ANOTHER more more useful rpm..."

 

This should read : "...the misunderstanding is coming from the correct idea that one can give away some power at high rpm to gain some torque at ANOTHER more useful, lower rpm.." But at a given rpm, you can't give away power to gain more torque ( because power = torque x rpm ).

Hi Marvmul

 

So.....If I understand you correctly, a cam which is advertised as a 'High Torque' cam is also a high power cam. For example, in my V8 offroader, I have a what is described as a high torque cam. From what you say, this could just as accurately be described as a high power cam....its just that the power (and torque) is delivered lower in the rev range than for a fast road car.

 

Is this what you mean?

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Hi John!

You are missing something!

My current figures are 165 hp(DIN) @ 5430 RPM (124 hp at wheels) / torque 226 Nm (167 lbs) @4590 RPM.

See my dyno figures at My dyno page.

My torgue is very flat and it is goood to handle.

See My Website for details about my modifications to earlier PI-engine and HESTEC EFI installation story.

I and my friend with with another TR6 just attended TR EUROMEET 2008 in south of Sweden last weekend and we drove about 1400km with no problems.

Martti B)

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What do you suggest I'm missing, Martti?

 

1/ As I said above, rolling roads are not comparable, or only in a very broad way. If two engines are tested on the same rollers, or the same angine after mods, then the figures can be meaningful, not otherwise.

2/ You found 124bhp at the wheels exactly the same as I did (on an incomparable rolling road!). Where did the other 40bhp come from? The transmission losses, to add to the wheels bhp and give an engine bhp, can be estimated from the run-down, but this is more a guess, based on the skill of the operator, and dare I say it, their wish to please the customer!

That Dennis Vessey suggested adding 20bhp, and your operator 40, shows the 'guesstimate' nature of engine bhp from a rolling road. Why should a TR6 transmisison have twice as much drag as a small chassis car?

 

I'm not here to compare bhp or willies! Just to promote the rational use of such measurements.

 

John

Edited by john.r.davies
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What do you suggest I'm missing, Martti?

 

1/ As I said above, rolling roads are not comparable, or only in a very broad way. If two engines are tested on the same rollers, or the same angine after mods, then the figures can be meaningful, not otherwise.

2/ You found 124bhp at the wheels exactly the same as I did (on an incomparable rolling road!). Where did the other 40bhp come from? The transmission losses, to add to the wheels bhp and give an engine bhp, can be estimated from the run-down, but this is more a guess, based on the skill of the operator, and dare I say it, their wish to please the customer!

That Dennis Vessey suggested adding 20bhp, and your operator 40, shows the 'guesstimate' nature of engine bhp from a rolling road. Why should a TR6 transmisison have twice as much drag as a small chassis car?

 

I'm not here to compare bhp or willies! Just to promote the rational use of such measurements.

 

John

John, what does wheel power 105.7 mean? This would seem to mean you have that at the wheels, and , estimated 125 at the crank. What am I missing here? Thanks

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You refer to the OP's power chart and readout?

 

That includes, run 2:

"Engine power(measured) 125.7hp

Wheel power (measured) 105.7hp

Power losses (measured) 20.0hp"

It then lists 'corrected' engine power and Torque.

 

The first equals the second plus the third, as one would expect, but I cannot understand how all three are said to be 'measured', or what the 'corrections' mean.

"There is no way on God's green earth of finding out the true transmission loss just by measuring the power at the wheels."

See: http://www.pumaracing.co.uk/POWER3.htm under "True Transmission losses", and any competent, honest operator.

 

IMHO, only the second can be measured. The second can be estimated and the first calculated from that estimate. And the measurement of the second is a highly moveable feast!

John

Edited by john.r.davies
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Just how much hot air can be expended on the subject of horse power ?

 

We're discussing 'rolling roads', or if you prefer 'chassis dynanometers'. An aid to tuning and development - no more, no less. A tool to compare the immediate result of changes to the engine. As a tool to measure absolutes, pretty much meaningless. Yes, you'll get a measure of peformance at the wheels, but an approximation not an absolute.

 

Even as a comparator tool, the 'rolling road' is useful only if you have a good working relationship with a skilled and reliable operator. The information it provides is, in any case, only part of the story - the remainder of the necessary development has to be carried out on the test track.

 

The only way you're ever going to obtain anything resembling meaningful absolute figures is on an industry standard 'bench dyno' running under industry standard conditions. And who needs them, for a TR ?

 

As for figures produced by the 'tuning' concerns . . . . too many of them are the product of imagination and b*llsh*t.

 

OK, so I sound even more cynical than usual ? Damn right. In a former life I served time as a 'works' team manager, the results of engine dyno and chassis dyno tests were crucial, as was the interpretation of those results. We never seemed to achieve the claimed horses of the opposition, we just concentrated on winning - and usually did.

 

Cheers,

 

Alec

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Look on rolling roads as tuning aids.

 

It's very difficult to compare the "at the wheel figures" from one rolling road to another - it's not just calibration but other factors play a part to - engine & air temperature, altitude/asmospheric pressure and so on.

 

Then to try and "calculate" flywheel power from road wheel measurements is little better than guess work trying to extrapolate power losses from the power used on overrun.

 

Likewise manufacturers figures from the 60's were to be taken with a pinch of salt. The standards of measurement were not that rigorous. the engines were at best blueprinted, and probably at the very least gas flowed. At worst they were modified as far as they thought they could get away with!

 

The CP(150) & CR(125) cars were subject to different power measurement standards - SAE for the former & the more rigorous DIN for the latter. Certainly there is no way the difference in real bhp is 25!

 

Similarly one should treat the claimed effects of one or other modification with large pinches of salt. If they worked as well as some claim the TR engine would found in the back of F1 cars!

Edited by andymoltu
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scan0002.jpg

 

 

However i am pretty disappointed with th HP figures.

Car now pulls well and very quick. At a bit of a loss why the hp seems so lo.

 

John TR6 CUE 836J

 

Seems to me that you are already where you want to be John.....? If your car is very quick and it pulls well, why bother with a piece of paper to confirm it?

It would however be much more interesting and informative if we could arrange a club 'drag race' somewhere to compare the real performance of our cars....

any ideas?

 

john

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Some interesting points.

 

Still puzzled with my results. Trouble is the rolling road is over a hour away,and at £50.00 plus the vat per hour its a very expensive game to keep going back. Went there originally to cure the flat spot at 3500 rpm job done on that score. Like i said before the car goes like sh... of a shovel and i compare this to my Volvo 200HP.

 

But having said that i am still disappointed not to see 150hp on the Graff.

 

Having thought about things in the last week i can not understand where the mechanic was getting the rpm pick up from the car, as the only sensor he had was in the exhaust.

 

I am sure that if there is so much loss throughout the transmission that the diff and wheel size also comes in to the equation?

 

Have posted a phone video ( not the best quality ) on you tube under the heading Triumph TR6 On rolling road

 

 

Do like the idea of a quarter mile run.

 

John TR6 CUE 836J

Edited by Maregratia
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I am sure that if there is so much loss throughout the transmission that the diff and wheel size also comes in to the equation?

 

Do like the idea of a quarter mile run.

Yes, wheel & tyre size & diff ratio. I changed my diff recently. If I put it back on the same rolling road, it would have become more 'powerful'. Huh. Take a look here.

http://www.tr-register.co.uk/forums/index....0dyno&st=20

 

Quarter mile? Santa Pod do Run What Ya Brung days every month, we just have to agree on here that we're going to turn up and fry our clutches, then hope it doesn't rain. <_<

You'll need a helmet, btw. You can find them cheap on eBay under open+face+crash+helmet, after all for this purpose they don't have to be any use, more dangerous driving on the motorway, oops better not get into that. :P

 

http://www.santapod.co.uk/calendar.php

 

http://www.rwyb.co.uk/

 

Here is a table of times by road cars, I see an MGB has done 11.9. Perhaps no one has made a serious effort with a TR. :blink:

http://www.rwyb.co.uk/cc_results2008.php

 

Ivor

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Yes, wheel & tyre size & diff ratio. I changed my diff recently. If I put it back on the same rolling road, it would have become more 'powerful'. Huh. Take a look here.

http://www.tr-register.co.uk/forums/index....0dyno&st=20

 

Quarter mile? Santa Pod do Run What Ya Brung days every month, we just have to agree on here that we're going to turn up and fry our clutches, then hope it doesn't rain. <_<

You'll need a helmet, btw. You can find them cheap on eBay under open+face+crash+helmet, after all for this purpose they don't have to be any use, more dangerous driving on the motorway, oops better not get into that. :P

 

http://www.santapod.co.uk/calendar.php

 

http://www.rwyb.co.uk/

 

Here is a table of times by road cars, I see an MGB has done 11.9. Perhaps no one has made a serious effort with a TR. :blink:

http://www.rwyb.co.uk/cc_results2008.php

 

Ivor

 

sounds good to me....count me in

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Perhaps we had better start a new thread for those seriously interested....sounds cheaper than a rolling road and we get a chance to see what mods really work....still got my helmet from Yamaha RD500 days :mellow:

john

 

The only thing you need to go drag racing at the famous Santa Pod Raceway is a valid UK driving licence, £10 for admission and a £20 signing-on fee. You'll be entitled to unlimited runs or as many as your nerves will allow! After each run you'll receive a personal performance print-out showing your reaction times to the start lights, 60ft, 1/4 mile, 1/8 mile times and terminal speed.

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Perhaps we had better start a new thread for those seriously interested

 

After each run you'll receive a personal performance print-out showing your reaction times to the start lights, 60ft, 1/4 mile, 1/8 mile times and terminal speed.

Go on then, start one ...

 

Btw, 'terminal speed' is that the point at which the engine exploded? :lol:

 

Ivor

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