Dan Timberlake wrote:I think the inertia loads of a centrifugal supercharger would be too much with the non-slip nature of a toothed belt drive on a quick revving engine punched in the lower gears
Not sure how an eaton supercharger compares
The Eaton is overdriven 2.5 to 3:1 and has a recommend upper limit of 14,000 for many applicationsBo. Centrifugal superchargers are geared up maybe 5:1 to 7:1 and more. Thus they're spinning the impeller 30,000 - 50,000 RPMs. Inertial loads go up by the square of the RPM so it's a much steeper curve with the centrifugal than the Eaton. The Eaton rotors are heavier than the centrifugal compressor wheel, but there's no internal gears/balls to add rotating mass.
Bottom line - it would seem the cogged belt drive adds more problems than it provides benefits.
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
Dan Timberlake wrote:I think the inertia loads of a centrifugal supercharger would be too much with the non-slip nature of a toothed belt drive on a quick revving engine punched in the lower gears
Not sure how an eaton supercharger compares
Packardv8 wrote:
The Eaton is overdriven 2.5 to 3:1 and has a recommend upper limit of 14,000 for many applicationsBo. Centrifugal superchargers are geared up maybe 5:1 to 7:1 and more. Thus they're spinning the impeller 30,000 - 50,000 RPMs. Inertial loads go up by the square of the RPM so it's a much steeper curve with the centrifugal than the Eaton. The Eaton rotors are heavier than the centrifugal compressor wheel, but there's no internal gears/balls to add rotating mass.
Bottom line - it would seem the cogged belt drive adds more problems than it provides benefits.
I did read about belt slip on a Rotrex blurb, usually it is the gear drive in the centrifugal charger that suffers the damage when running a toothed belt drive.
I don't intend on running the Eaton at a 2.5 to 3-1 ratio, my charger will be sized larger than what most people would choose, and being on a diesel engine that redlines at 4000 rpm the 1.5 to 1 drive ratio (this is a low boost application) will only spin the charger to around 6000 rpm, so rotating mass in the charger wont be extremely high. The heavily built engine isn't as responsive as a lightweight gasoline motor, well not without a blower on it, plus it does have a weighty flywheel, oh, and diesels don't backfire, so there aren't going to be any sudden changes in engine speed. After thinking about it I don't think that the cog belt drive will present any major problems.
Last edited by roadrunner on Sat Oct 11, 2014 6:14 pm, edited 2 times in total.
af2 wrote:When you machine the pulley's make them wider just in case you need a stronger belt in the future.
I wasn't going to get the pulleys machined, I intended to use the Toyota cam drive sprockets as they have done a few hundred thousand kilometres yet show no obvious signs of wear. Now I'm leaning towards using the aircon compressor twin v belt drive, but the aircon delete might be regretted when the ambient temps hit the low 40s C. here in the summer...Hmmmm
Use two cam belts and two set of toyota pulleys side to side.
A friend of mine turned a 3-71 detroit blower with a off the chart overdrive ratio trying to feed a 318 SBM. Belts did well, but make sure your pulleys are firmly bolted.
roadrunner wrote:... oh, and diesels don't backfire, so there aren't going to be any sudden changes in engine speed. After thinking about it I don't think that the cog belt drive will present any major problems.
The old Mercedes 300 SDL had problems with tearing up the tensioner. I think this resulted from deferred maintenance of the shut-off valve and glowplugs. The uneven firing puts huge stresses into the crankshaft which are transmitted to the serpentine belt (grooved). Crack that whip. Be careful about maintenance.
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Try to find a supercharged Mercedes in a wrecking yard, you can benefit from the R&D they did.
Cogged and V-belts both sound like trouble.
You could also look at what some of the aftermarket companies like Edelbrock did but keep in mind an organization like Mercedes would likely spend 1000 times the effort on R&D with vastly better qualified engineers.
If he is using a smaller driven pulley, that might be trouble, IIRC a guy I knew (annoying jerk) was upset that his stock sized pulley made noise sometimes. Mercedes ended up putting larger pulleys all around on warranty
="kevin Johnson" The old Mercedes 300 SDL had problems with tearing up the tensioner. I think this resulted from deferred maintenance of the shut-off valve and glowplugs. The uneven firing puts huge stresses into the crankshaft which are transmitted to the serpentine belt (grooved). Crack that whip. Be careful about maintenance.
="schmidtMotorWorks" Try to find a supercharged Mercedes in a wrecking yard, you can benefit from the R&D they did.
keep in mind an organization like Mercedes would likely spend 1000 times the effort on R&D with vastly better qualified engineers.
The Eaton builds that I have followed on the net always seem to have serpentine belt slippage problems, especially when a smaller charger pulley is swapped in, hence my interest in a gilmer system. I don't like the idea of what often seem to be over tensioned serp. belts putting strain on the crank nose and other bearings in the drive system. I'm still undecided on a drive system, and am presently favouring the 25m.m. cambelt at this stage, especially after replacing a few previously after 60,000 miles of driving the camshaft and injection pump and having trouble distinguishing the new belt from the old as far as visible wear goes, it seems that the Toyota engineers have also done their R&D Jon!
Mercedes used a different tensioning setup for the petrol version of the straight six. Seriously, I am sure they tested the hell out of the diesel system but letting the design loose to be abused by USA drivers in ways hardly imaginable is the true crucible.
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Kevin Johnson wrote:Mercedes used a different tensioning setup for the petrol version of the straight six. Seriously, I am sure they tested the hell out of the diesel system but letting the design loose to be abused by USA drivers in ways hardly imaginable is the true crucible.
I'm sure the various vehicle engineers have to give their vehicles a specified service life, in fact I'm sort of glad that they do, otherwise we'd still be driving something like this-
800px-Thermador_Car_Cooler.jpg
(probably lacking the air-con too Kevin ), and the unemployment lines would be choked with engineers from every major manufacturer.
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One of the interesting long-term design tests performed by (non-abusive) real-world drivers was in determining that the original construction of the vacuum pump would last about 250,000 miles before bearing failure and wide-spread destruction. Mercedes did subsequently redesign it.
One of the poorer sagas was in watching the regulatory response to Bosch's test data on injection pump durability with different diesel formulations. Solution? Change the definition of the expected product life-span.
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Kevin Johnson wrote:One of the interesting long-term design tests performed by (non-abusive) real-world drivers was in determining that the original construction of the vacuum pump would last about 250,000 miles before bearing failure and wide-spread destruction. Mercedes did subsequently redesign it.
One of the poorer sagas was in watching the regulatory response to Bosch's test data on injection pump durability with different diesel formulations. Solution? Change the definition of the expected product life-span.
The regulators (Bosch bean counters?) decision to accept a shorter lifespan, and then market high cost replacement injection components is probably contributing to the low cost counterfeit items currently flooding the industry, or does another body govern the Bosch product by specifying fuel composition?
Kevin Johnson wrote:Well, the one practical thing I could offer is to be very careful about from which location you choose to rotate the belted assembly and in what direction you rotate it. Rotating from a larger cog might be very handy but will stress the belt and rotating in reverse can also cause problems. I think a spring loaded tensioner and perhaps a separate damper might extend the life as well. Perhaps these are already present
The engine is a 4 cylinder 3.1 litre diesel, I linked the victory site in my previous post because it's very informative. I am planning on using the crank snout for the drive, and am tossing up between using the Toyota cambelt and sprockets and a twin v belt drive. After reading the gates information on the toothed belt drive that needs both cogs to be in very close/accurate alignment for long belt life I am now favouring the twin v belt setup which is more forgiving in this area. . If I take the aircon compressor off I can use its present twin v belt drive and hopefully its mounting bracket. I previously didn't realize that a small amount of belt slippage can be a good for long charger life. Thanks for the input!
back in the day I installed a few B&M superchargers on BBC in boats and they used a "V" belt drive and never saw a problem
), and the unemployment lines would be choked with engineers from every major manufacturer.