8hp

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Rototest showed a difference of 20 hp between the manufacturer's stated output and power at the wheels on a Defender 110 and 88hp on a RRS FWIW.

Rototest 110

Rototest RRS

[Guest otchie1]

IIR the lecture then if you want to maximise power you need to start with individual inlet tracts and then tune the tract lengths so that the momentary back pressure wave caused by the poppet valve shutting can be used to compress the next slug of incoming air. Or forget all that and use a turbo :-)

To my mind a 4hp drop is not excessive for the peace-of-mind a snorkel gives when the going gets damp; presumably this is only at peak test rpm and not across the whole graph?

[white90]

I was wondering about having two snorkels (not just because i'm a tart )... i assume this would help easy the situation?

Probably not an issue unless you have a L/R

[nicks90]

To my mind a 4hp drop is not excessive for the peace-of-mind a snorkel gives when the going gets damp;

that 4bhp drop was also with fresh filters. Having a snorkel prolongs the life of a filter substantially, so i would suggest that in the real world testing over 6k miles, that 4bhp drop would not actually average out to be a drop at all over a non-snorkelled engine. How much power does a blocked up filter sap and when would a filter be classed as 'blocked enough' to start restricting an engine - 2000 miles, 3000???

i change my air filter every 5k and have a cyclone top on my snorkel. Very very rarely do i find any staining or sooting on my air filter. Looks almost like new and seems a waste to change it...

[landroversforever]

Probably not an issue unless you have a L/R

Planning tony planning..... Its all in the planning!

[streaky]

I've been out of the country for the past week without email but can see that this thread has gone off at the usual tangent.

The first picture shows;

Blue graph = with snorkel connected.

Orange graph = without snorkel connected.

Pay no attention to the Red, pink & Green lines.

Here's a question for the experts that can be answered from the second dyno plot. Again...pay no attention to the erratic lines on teh lower portion of the graph.

How much power will the 4.6 engine lose when the viscous fan comes into effect?

S.

[q-rover]

This is quite interesting.

At the weekend I was reading an old LR mag article about the RR P38 Callaway

special edition. After Callaway had got their hands on a few LR 4.6L V8's and

dyno'ed them they found that most were putting out around 170/ 180hp, which is

quite significantly less than claimed.

Once Callaway had done modifications, maily to the inlet side (the short engine

was standard LR) they managed upto 275hp, but sttled for around 250 with a claimed

240hp in the sales blurb.

To me this would indicate that the good old RV8 never realised it's full potential

under LR and that even their claimed figures can be dubiious.

[Aragorn]

q: its not surprising they were able to make a big power increase on the "Thor" 4.6 motor, the inlet manifold was designed specifically for low down torque at the detriment of peak power.

A simple manifold change would likely be able to yeild a much higher headline figure, but obviously there would be a loss further down the revs.

Interesting on the 180hp figure though, i do personally feel that a 220hp engine should be producing more than 100hp at the wheels, even thru a 4wd system, but without the coast down figures we cant really do anything but guess in this case how much power the motor actually has.

[HPLP]

q: its not surprising they were able to make a big power increase on the "Thor" 4.6 motor, the inlet manifold was designed specifically for low down torque at the detriment of peak power.

A simple manifold change would likely be able to yeild a much higher headline figure, but obviously there would be a loss further down the revs.

Interesting on the 180hp figure though, i do personally feel that a 220hp engine should be producing more than 100hp at the wheels, even thru a 4wd system, but without the coast down figures we cant really do anything but guess in this case how much power the motor actually has.

From talking to a test engineer at Jaguar/Land rover, nearly all manufacturers base their power dyno figures with nothing connected to the engine including no alternator/power steering pump/water pump.

So Im not too surprised at the drop.

H

[Aragorn]

They stopped that nonsense years back as far as i was aware.

A quick bit of googling gives us the "ECE R24" european standard for measuring engine power, which states everything required for the engine to run must be fitted. The cooling system, intake and exhaust system must all be as fitted in the vehicle.

http://www.unece.org/trans/main/wp29/wp29regs/r024r2e.pdf

They can remove the PAS and AC pumps, but in an unloaded state they arent going to draw very much power at all anyway, certainly not 40hp.

DIN 70020 is seemingly similar.

[Lara]

70020 is what we use,

However in our modern race prep years we never tested a single engine from a manufacturer that gave their quoted power. Some Italian makes were 15 to 20% off

Lara

[bishbosh]

Some Italian makes were 15 to 20% off

Probably rusted away, like anything else to do with Italian cars!

[Lara]

That is one excuse I didn't hear

Bloody believable though

Lara

[Bull Bar Cowboy]

70020 is what we use,

However in our modern race prep years we never tested a single engine from a manufacturer that gave their quoted power. Some Italian makes were 15 to 20% off

Lara

From what I see American HP must be the most optimistic ...........