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Cressa

Karmann the Corrado

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7 minutes ago, Dox said:

I'm no expert, but Dave Walker at Emerald is:-

EmeraldM3D.com - Rolling Road

 

How Rolling Roads Work

power-curveBefore we consider how a rolling road measures power output, it helps to understand what we are measuring.   We often talk about bhp (brake horse power) as if it was something that existed, rather than the reality of it being a convenient number - which we have calculated.  Bhp is a rate of doing work and in order to do work you need to put in some effort and then you need to see a result for that effort.  The effort is, in our case, the torque generated by the engine.  The result is the distance moved by the flywheel (expressed in rpm).  The simple formula for calculating bhp is based on 33,000ft lbs of work being done in one minute.  This amount of work is regarded as one horsepower.  The formula is: HP = Torque x rpm over 5252.  From this you can see that when the rpm is at 5252 the HP and the torque are the same.  If the power and torque lines do not cross here on the graph then someone is telling you porkies!   We use the term "Brake" horsepower because the engine torque is measured on a device called an Engine Brake, or dynamometer as it is more correctly known.  Dyno's measure torque at a given rpm and then we calculate the bhp from there.  With an engine bolted to a dynamometer we take the torque reading directly from the flywheel and without any form of gearbox.

nice explanation Dox thanks 😄

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Posted (edited)

196911c7654d2f2a66a29117ad7dd19d.jpg

If 118kw is at the wheels the above indicates a 32bhp loss over standard due to transmission losses which is about right

Edited by Dox

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Sorry for the delay in sending pics of the bonnet rib cutout. The white is adhesive from the tape i used to cover it. I covered the area with masking tape, and cut through that as opposed to using the dremel directly. The bottom of the pics are towards the engine

20210108_154934.jpg

20210108_154942.jpg

20210108_155036.jpg

20210108_155043.jpg

20210108_155058.jpg

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19 hours ago, Dox said:

196911c7654d2f2a66a29117ad7dd19d.jpg

If 118kw is at the wheels the above indicates a 32bhp loss over standard due to transmission losses which is about right

I did those calcs and  gained comfort from them, especially as the car does not feel sluggish or under powered. Thanks Dox for putting this stuff up.

Fla great pictures, thank you.

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Hoping to get time to do a compression test this weekend. Does anyone have any top tips for me. 😇

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Fully charged battery, throttle jammed open, all plugs removed.

it would be a good idea to unplug the crank sensor (no spark or fuel) and not to stand in-front of the car if someone else is turning the key - mine shot coolant out of the plug hole into a light fitting blowing the power...

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🤣🤣 cheers dox, hadn't thought or read about the crank sensor 👍 

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6 minutes ago, seanl82 said:

Worth warming the engine a little beforehand as well. 👍

👍

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Thats a good link, thanks for sharing.

Is it necessary to remove all the plugs or can they be removed one at a time?

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39 minutes ago, fla said:

Thats a good link, thanks for sharing.

Is it necessary to remove all the plugs or can they be removed one at a time?

Otherwise the starter is struggling against 5 cylinders with compression, plugs out, throttle open gives faster cranking but still not as fast as normal idle

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57 minutes ago, Dox said:

Otherwise the starter is struggling against 5 cylinders with compression, plugs out, throttle open gives faster cranking but still not as fast as normal idle

thanks Dox, makes sense.

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Took her out for a warm up today to enjoy the last day of her road tax 😊, then it was time for the compression test. I had purchased a cheap US pro kit which has lots of bits that I certainly did not need. The biggest worry was that the thread adaptor that goes on the end of the hose would get left behind in the cylinder head, damn that would be trouble, but all went surprisingly well.

I had never this before, but removing all ignition leads, plugs and the fuel relay 167 was quick and easy enough. (Didnt do the crank sensor Dox, I totally forgot)

Bloody immobiliser needs resetting everytime I switched the ignition off 😠 and first attempt I got Zero on the gauge !! Thankfully just a loose joint at the gauge. .

Cylinder 1- 148

20210131_161327.jpg

Cylinder 2 - 177

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Cylinder 3 - 165

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Cylinder 4 - 180

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Cylinder 5 - 162

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Cylinder 6 - 175

20210131_161101.jpg

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Now I'm not for 1 minute thinking those readings are accurate and the engine is mint, but she does pull well and does not smoke. The car is on 122,922 miles I think I have done towards 1k miles on the new plugs so I compared them to the old ones I removed

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And this is the tester I used

20210131_162901.jpg

Edited by Cressa
Mileage addition

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Hope it is the gauge misreading, cylinder 1 is pretty low. Iirc, anything between 160-180 is within tolerance.

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1 minute ago, seanl82 said:

Hope it is the gauge misreading, cylinder 1 is pretty low. Iirc, anything between 160-180 is within tolerance.

And I thought about 120 would have been good for an old engine 😄. Sean, i certainly am no expert at this and it was my 1st time. I had read that if within 20% then not to worry..... I was expecting 1 and 6 to be lower surprisingly..

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BOLLO#, just realised I didnt do it with the throttle open..... for ease I was turning the key through the open window. I may have to redo this now. I suppose it may be interesting to see if it differs.

I may also have a Carbon clean, just to see if that makes a difference too..just a thought

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How long was the car off the road for? How many miles since?

I’d plan a road trip before I checked again and if I had those figures quoted I’d be more than happy with 25 year old engine?

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9 hours ago, Dox said:

How long was the car off the road for? How many miles since?

I’d plan a road trip before I checked again and if I had those figures quoted I’d be more than happy with 25 year old engine?

Was off the road for 5 years and has done just 800 miles since roadworthy.  I will give it a roadtrip first . I dont know how well calibrated the gauge is , but I am happy with the results. Atleast it isnt on its arse thankfully 

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COMPRESSION UPDATE 

So I did the compression test again today, with the throttle fully open

1-175, 2- 177, 3 -175, 4-180, 5-173, 6-173

Zero miles since the last test. Latest figures in blue. Now I'm happy

20210208_131946.jpg

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27 minutes ago, Cressa said:

COMPRESSION UPDATE 

So I did the compression test again today, with the throttle fully open

1-175, 2- 177, 3 -175, 4-180, 5-173, 6-173

Zero miles since the last test. Latest figures in blue. Now I'm happy

20210208_131946.jpg

chicken dinner - sounds very healthy 😄

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