What is "normal" for pulling a TT?

Turbochargers are generally more efficient than a mechanically driven supercharger, and are capable of much higher boost pressures.

Reply to
Max Dodge
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I think you also have to factor in engine life and wear...

A gasser is designed to make power at higher rpm than a diesel... gearing won't change that... add gears with more grunt to either and you're operating at higher rpm ranges and asking for more/faster wear...

When my buddy and I are towing our trailers together, he gets 12 mpg towing an

12,000 pound 5th wheel with his f-250 doing about 1,700 rpm, while we're getting 8 mpg towing a 6,000 pound tt at 2,800 rpm....

We both have 3.5 (approx) gears... I could almost keep up with him on hills with a 4:10 gear set, but at what rpm and mpg??

IMO, not worth the cost of regearing..

Mac

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Reply to
mac davis

try not eating them so fast... use them for counting, like humans do with fingers..

Face it, Buggs, without an opposing thumb, you're screwed.. *g* Mac

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Reply to
mac davis

That would be the one with the K&L, right?? Mac

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Reply to
mac davis

I dunno. I seem to do ok with the ar and springfield. Maybe I'm just getting lucky??

Denny

Reply to
Denny

Try to actually answer his question. Mechanical superchargers do work better at low RPM. Turbo chargers are not capable of "much higher boost pressures." That's a function of the size of the supercharger and how fast it's driven.

Al

Reply to
Big Al

Without getting inot a long drawn out technical paper, I did answer his question. THere are of course, many variables in the field.

"Work better??" True, turbo's have a lag time, dependant on size of turbo and engine to which its mated. However, this lag is not dependant on "RPM" as much as the two aforementioned variables. It is also notable that the lag time on a properly designed setup is minimal. Thus, since the turbo is capable of higher boost numbers, the lag time is acceptable in a trade off for more boost.

In general, your statement is INcorrect. A turbo will spin at much higher RPM relative to engine RPM than a supercharger will. True, superchargers can be set to a boost level with pulley/gear ratios, but this ALSO limits what a supercharger will be capable of. It may either boost "too little" at upper RPM's, or "not enough" at low RPM's.

A turbo, on the other hand, can be sized to boost according to engine LOAD rather than RPM, using a wastegate to regulate boost pressures. This is because one key factor is the expansion of the exhaust gasses. This expansion becomes (as a percentage) larger when more fuel is injected, even if RPM does not increase proportionally. Thus the turbo adapts to load while the supercharger will not.

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More details can be found here. Note that the above link is a SUPERcharger sales outlet, so the info could be biased towards the superchargers, yet they play it straight.

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Nifty graph shows exactly why the turbo is more popular: more usable HP. This is because of the higher percentage of efficiency from a turbo.

Reply to
Max Dodge

Probably.. my dad used to say that luck was caused by hard work... Mac

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Reply to
mac davis

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