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Turbo vs blower

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Old 12-05-2007, 01:24 AM
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Originally Posted by HabanaJoe View Post
I only seen one of these one type out at Columbus outside the dyno alley and this is how it worked. The turbo had a very long shaft with a small turbine engine driving it. They would ignite the turbine and run that while they were sitting still. The trubine would drive the trubo charger and keep boost on the engine while it was off. The turbine also dove a small hi-hertz generator that would keep the tank supplied with power because batteries go dead quickly. The heat trails from that could be ducked down and were small enough not to make a real differnce.

When they spotted an incoming they could hit the starter and the engine fired up with near full boost to get instant power to pull it ouy of the hole and away from the incoming.

When I looked at it all I could see was piping all over the place, but Carl Kuner if you guys know him from Cummins was explaining it and I just was like "What?"
OK, now I see why our taxes are so high!

Michael
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Old 12-05-2007, 02:25 AM
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First I'm an idiot and most times above simple routine stuff I'll end up paying someone.

Not sure if this has been mentioned. One of the finest some what affordable Japanese sports cars made was the 1992 and above Mazda RX7's with their sequential twin turbochargers set up.

quoting an article in Hemmings Sports and Classics mag:
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The sequential twin turbocharged system was a very complex piece of engineering, developed with the aid of Hitachi and previously used on the domestic Cosmo series (JC Cosmo=9095). The system was composed of two small turbochargers, one to provide torque at low RPM. The 2nd unit was on standby until the upper half of the rpm range during full throttle acceleration. The first turbocharger provided 10 psi of boost from 1800 rpm, and the 2nd turbocharger was activated at 4000 rpm and also provided 10 psi (70 kPa). The changeover process was incredibly smooth, and provided linear acceleration and a very wide torque curve throughout the entire rev range.
For a mass produced sports car from Japan that had turbos was a blast to drive. More from a driver vs mechanical engineer can say for driving thats one of the best turbo apps ever sold!
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Old 12-05-2007, 07:25 AM
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Hyperbar engine? Not heard about that for YEARS! Last time I saw that mentioned was in LJK Setright's "Some Unusual Engines" (Sadly now out of print).

Big military diesels have some great features on them for "destruction avoidance". Modes like: forget cooling fans, forget pumps, forget smoke, forget turbo speed limts. JUST GIVE ME ALL THE BOOST YOU CAN OR I'M DEAD. Great fun for about 10s!

We've not even mentioned the Napier Nomad yet, there's a real "missing link"! Anyone remember that?

I have to admit that I'm very much on the turbo side of the fence as these things go but they do have response issues and I can see that that would be a major issue where rough water throttling is concerned. However, I'd have thought that a lot can be learned here from the World Rally Championship engines. These 2l turbos run such effective anti lag systems that (an automated version of the pumping the throttle to keep the turbos working) by using afterburning in the exhaust that they can now run nearly full boost at idle. This generates levels of response that are required for rallying together with the very high levels of boost that are used.

Gasoline is slightly better than diesel though in this respect as you don't lose as much EGT during load transients as the AFR remains constant (which it doesn't with a diesel) and the airflow is reduced much more significantly due to the effect of a throttle which of course the diesel doesn't have. You'd have thought that the offshore diesels could use exhaust injection to maintain turbo speed during transients though. That's very effective.

On the low speed torque issue I wasn't so much thinking about racing boats as for more general usage of boosted engines where surely onto plane performance is an concern?

I think this is where the modern generation of European turbo diesels are going to change things a lot: A lot of the latest engines are already generating 100bhp/l and nearly 200Nm/l with twin sequential turbocharging to solve the response issue. Together with 1800-200bar common rail systems yielding up to 5 injection events per cycle, things are changing a lot. Once these technologies start making it through into larger engines suitable for boats, I think that this power source will start making a name for itself even in performance boating. I mean who'd have thought that BMW would start making diesels that perform nearly as well as their best gasoline powertrains (EU market only though folks).

Didn't Schwitzer get swallowed up by KKK? Which then became 3K Warner when Borg Warner sold their share in IHI Turbos (ISHI Warner) and bought KKK? Of course these days it just good old Warner Turbo Systems so two great old names have disappeared. Isn't the turbo world incestuous?

This really is a very interesting thread!
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Old 12-05-2007, 10:04 AM
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I left Schwitzer for Ford engine division aq few years before they were bought up. KKK made an offer a bit before I left but Schwitzer turned down the offer. Borg Warner then purchased Schwitzer later. Then BW then bought up KKK.
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Old 12-05-2007, 10:16 AM
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Afterburning, hummmm direct fuel injection into the exhaust pipe might look cool for grins and giggles.. Didn't Sonny Leonard like 10 years ago build a twin turbo supercharged big, big block remember seeing it in a show once I think in a Nova.
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Old 12-05-2007, 10:47 AM
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It's a pretty effective method of anti lag actually. Especially in a diesel where there's lots of excess oxygen in the exhaust at low loads.

On gasoline applications, it wouldn't be used. You don't need to inject fuel into the exhaust these days to do anti lag but you do use an air bypass pipe to supply air to the exhaust manifold. The fuel that is burned comes through the engine in the normal way. This is done using conventional engine management as the rally cars do.

Last edited by Ruaraidh; 12-05-2007 at 10:56 AM.
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Old 12-05-2007, 12:09 PM
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Originally Posted by Ruaraidh View Post
It's a pretty effective method of anti lag actually. Especially in a diesel where there's lots of excess oxygen in the exhaust at low loads.

On gasoline applications, it wouldn't be used. You don't need to inject fuel into the exhaust these days to do anti lag but you do use an air bypass pipe to supply air to the exhaust manifold. The fuel that is burned comes through the engine in the normal way. This is done using conventional engine management as the rally cars do.

What do you use to supply air the the exhaust manifold ?

Thanks
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Old 12-05-2007, 12:19 PM
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The initial flow is caused by the inlet pressure spike before the throttle as it closes. After that, the boost generated by the antilag is enough to cause air to be blown across into the exhaust manifold.

The engine airflow is very low (as the throttle is closed) so the pre-turbine pressure is also low thus giving a +ve pressure differential between the inlet and exhaust which causes the air to flow to the exhaust. Most of the energy that drives the turbo is contained in the temperature of the gas not the pressure (enthalpy).

The control valve is controlled by the ECU which also monitors turbo speed and EGT. The rally car systems are very sophisticated but we are talking racing money here too!! Just brought it up as I thought people might find it interesting.

Last edited by Ruaraidh; 12-05-2007 at 12:22 PM.
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Old 12-05-2007, 12:25 PM
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That is just so far out there, very cool stuff. Never realized the old tank engine technology had matured so much!!!!

God, I'm getting old!
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Old 12-05-2007, 01:36 PM
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so no lag?
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