bantam turbo

[Hedd_Jones]

The difference with a turbo is that itll blow 5lbs from the second its spooled up. Comparing it to supercharge boost which is variable from none to a desired maximum at a certain rpm is very different.

Im also very interested to see how it performs. And the engineering is superb. Dont get me wrong. But the pictures of it when it goes pop are going to be as interesting as Charles supercharged engine calamity was.

[Zetomagneto]

Hedd, I think you have that the wrong way round.A supercharger is blowing as soon as the engine starts

[Hedd_Jones]

But is the blow on a supercharger not variable to a maximum? given the mechanical drive? Yes it blows from tickover.

My understanding was that a turbo doesnt blow until you have sufficient exhaust flow, but it is essentially then ON at constant pressure.  Limited in pressure by the wastegate settings? Mind ive never got my head around variable vanes. The ones on my Mondeo got stuck giving too much boost and the electronics went bazerk and put it in limp mode. The garage predicted about a 1500 quid bill so I sacked them off anf a mate fixed it by drilling a hole in the inlet manifold, tapping it for a blanking plug. Aralditing a drinking straw to a tin of Mr Muscle oven cleaner and depositing the whole can in my turbo. Then putting the blanking plug in. 20 mins later we starter her up. A prod of throttle and a black cloud later and it was fixed

[Zetomagneto]

The supercharger should be matched to the engine size, roughly speaking a 4 cylinder engine of 2ltrs would injest 1 ltr of air per revolution, you would want a supercharger that displaces something like that per revolution, you can then adjust boost pressure by drive ratio, the faster you drive the charger in relation to the crank the higher the boost.Hopefully if you gear it right the pressure will be linear,
in other words the same throughout the rev range.

[Alan]

Hedd, you should market that idea. It’s brilliant.
However I don’t think 5psi is enough to trouble a well put together engine. In any case I’ve always been of the opinion that it’s valve loading that separates cylinders from the block, not pressure in the cylinders.

[Hedd_Jones]

Zeto

When Ive watched youtube vids, the blown cars are all custom and use 'availible' blowers rather than matched ones.

Theres a very good comparison of a blown MX5 (is it a Miata i  America  terms?), vs a Turbo'd one. Both fairly back street garage jobs. They put both on the dyno, and carried out driving tests on both. The turbo was set so the peak boost was the same as the supercharged car. The pressure of the supercharged car was certainly not constant. It was a curve.

The dyno results for the turbo car pissed all over the blown one. But this was reversed in the driving tests except for the drag race. The blown cars power being so much more usable.

All very interesting stuff.

Alan. My mate runs Taxis to intergalactic milage. Apparently it was standard practice on a Euro 4 TDCI Mondeo 10 years ago

[steve anderson]

Land speed racing is standing start , El Mirage California is one mile on hard dirt with shutdown  distance ..  Bonneville Salt Flats up to 5 miles , I only need one  mile to get top speed . Car has 5.25 ratio now , will have MG MIDGET 4.22 ratio later this year with hydraulic brakes .  STEVE

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Valve springs have 90# pressure open valve , 45# seated  STEVE

[Steve kay]

Good lord, if this description of Mondeo tuning  was corrected/censored ten hours ago, what did the original describe?

[jansens]

Hedd, if that's the comparison the Mighty Car Mods (Aussies) did they were using a centrifugal supercharger. The pressure in those related to engine RPM, similar to a turbo. The more traditional blower is the roots (and modern screw) type which is positive displacement, they move the same amount of air per revolution, so the boost curve will be far more flat from idle.

Dyno pulls you see online are interesting but they are always(?) done at WOT. Good for drag cars or race cars. That's why in these YouTube tests when they drive the cars more normally on the street the results seem different.

Steve, I guess for land speed stuff you are WOT most of the way?

Simon

[stuartu]

Thanks for the info, Steve.

Regards,
Stuart