What the hell?

[steve_t]

Never compared the two on the dyno sorry mate. As for the life of the headers...can't say. It was on my race bike. Two of the guys here have HD's with 2-1's on them, both wrapped. They've done thousands of km's...and they're both fine.

Sweet. Good to know. Never wrapped any exhausts myself. Just gotta take what you read on car forums (and all the interwebs) with a grain of salt

[Crasherfromwayback]

Sweet. Good to know. Never wrapped any exhausts myself. Just gotta take what you read on car forums (and all the interwebs) with a grain of salt

I've wanked on about our dyno here many times...but it really does not lie, and is way advanced compared to a dynojet jobbie. Was impressive enough for Yoshimura Japan to fly out their top boys to suss it out, and they then had three made for themselves after viewing it in action!

[jonbuoy]

http://www.epi-eng.com/piston_engine...efficiency.htm

Like I said before, look up thermal efficiency. If you read through the article and actually understand the physics involved you will see that there is a significant loss of calorific energy to the engines cooling system. If you did not need to cool an engine (i.e there were no expansion of metals or melting to worry about) then the engine would run most efficiently with no cooling whatso-ever, particularly if it were well insulated to keep all of the extra heat from combustion in. Theres only one place for the heat to go if that were to happen, and that is into another form of energy, likely to be more useful.

Yes I realise the website is based on aero engines, but it is the same concept for every engine. Unfortunately engines can only be run up to a certain temperature before things go wrong, and thats where the cooling system comes into play. If the engine bay is warm, and the cooling is efficient, then a good balance is easier to maintain. A lot of performance engines are therefore run at a higher temperature than the average, an example being BMW engines which run at close to 90degrees, where a Ford Telstar runs at just under 70degrees.

That article relates to increasing Efficiency (fuel economy) extracting the most energy/litre of fuel (which is more important in an aircraft than a performance car) - nothing to do with increasing or making more power from an engine regardless of fuel economy.

http://www.f1technical.net/features/250

[jonbuoy]

And an article below on increasing fuel economy:

http://www.torquecars.com/tuning/tuning-mpg.php

Regardless, personally I´m going to be fitting a heat shield or header wrap over my exhaust manifold as the supercharger sits on top of the exhaust manifold, not to take advantage of heated exhaust gasses.

[blackdog]

\Quite to the contrary, IIRC the energy from petrol is converted to only about 10% motive force and 90% is wasted as heat.

Impossible! Because a percentage of the potential energy is also converted to light.

[steve_t]

Impossible! Because a percentage of the potential energy is also converted to light.

Approximately... some is also dissipated as sound. Jonbuoy's article says something similar though the figures are different. The point is that for the energy contained within a volume of petrol, the amount that is converted to motive force is relatively very low

[huff3r]

That article relates to increasing Efficiency (fuel economy) extracting the most energy/litre of fuel (which is more important in an aircraft than a performance car) - nothing to do with increasing or making more power from an engine regardless of fuel economy.

http://www.f1technical.net/features/250

I give up. Your not at all paying attention to anything I say, nor it seems correctly interpreting a technical article.

Efficiency + More Fuel = Moar Powaaah.

But whatever, sure cold engines are fantastic, i might go remove my thermostat and add 3 more radiators to my car to lower its temps then...

[bogan]

Thermodynamics is a mystery to the commonfolk of KB...

Difference between a working knowledge, and an actual knowledge. 'Common folk' often know enough to keep things working, or make small improvements, like cold air intake is good, they then misunderstand the reasons and come up with silly conclusions like cold engine is good!

Don't get me wrong, a working knowledge is fine for most people's self maintenance and minor tuning needs (though carb tuning still flummoxes more than it should). But if you want to do some uncommon modding, or design work, it's insufficient.

[jonbuoy]

I give up. Your not at all paying attention to anything I say, nor it seems correctly interpreting a technical article.

Efficiency + More Fuel = Moar Powaaah.

But whatever, sure cold engines are fantastic, i might go remove my thermostat and add 3 more radiators to my car to lower its temps then...

Maybe you should start working for a top fuel Dragster team, get them to improve their "fuel efficiency". You seem to know more than engine tuners and dyno results. Are you actually reading any of the links? Where have I mentioned a "cold" engine? Efficiency + More Fuel = rich mixture! You need "moar" air to burn "moar" fuel.

If you modify a standard engine (especially adding forced induction) to make significantly more power (burn more air fuel mix) more waste heat will be generated. If that heat builds up in the engine compartment by it will affect the temperature of the intake charge, longevity of everything from the battery to the ECU not to mention heating up brake fluids and the fuel itself. This is a bad thing. Thats my point. Exhaust pipes emit a fair amount of heat into the engine bay - covering them with a heat shield, header wrap will reduce the amount of heat in the engine bay. Which was my original point a few pages ago. Or will the latest craze for the WRC, F1, Moto GP teams be to seal up those engine bays, blank off those radiators as we now know - moar heat=moar power

[ducatilover]

Maybe you should start working for a top fuel Dragster team, get them to improve their "fuel efficiency". You seem to know more than engine tuners and dyno results.

You'd probably melt the exhaust wrap off the pipes on one of them and there's no need for it, the pipe length is so short and scavenging effect would be redundant and keeping heat in one of those things is NOT a good idea....after all, the exhaust valves are red hot and igniting the fuel after half track

Find me a dyno that can handle their power too....

[Big Dave]

It's called 'lagging' you retards.

[nzspokes]

It's called 'lagging' you retards.

I was going to raise that point but thought it would make me sound old.

[imdying]

And I can assure you header wrap works!

What does works mean?

[Crasherfromwayback]

What does works mean?

Like a works bike!

[imdying]

.