NA to Tubo

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JamesF
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Location: South Yorkshire

Post by JamesF » Tue Nov 25, 2014 6:18 pm

Unless you re calibrate the injector pump to accommodate the turbo it may not make any difference adding the turbo or it may not run very well. The fuel delivery may be sufficient but you won't know till the turbo is fitted.

When David brown built the turbo engine they didn't just bolt a turbo on, the whole engine was engineered and designed to be turbocharged.

It might work very well and if you're not going to work it hard it may be absolutely fine.

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bedwards1966
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Post by bedwards1966 » Tue Nov 25, 2014 6:35 pm

I can't see it running any worse - you can run a diesel lean with no ill effects.
Adding the turbo will increase the air and will ensure all the fuel is being burned, presumably the tractor has some black smoke at the moment which the OP would like to reduce. But there won't be much increase in power without also increasing the fueling which people normally do when adding a turbo as they are aiming for an increase in power.

Guest

Post by Guest » Tue Nov 25, 2014 7:32 pm

Increasing the amount of fuel by opening up the injector pump does not increase engine power, to do that you use the tractor in a gear and at the revs suitable for the job you're doing with it! In the fitting of a turbo charger you are basically introducing more air into the cylinders by compressing it therefore creating a greater air/fuel mix which under the compression of the rising piston in the bore compresses the mixture even more resulting in a bigger 'bang' which in turn results in more power. I understand that David Brown did trial a turbo'd 3 cylinder engine but found that the resulting power increase was negligable for the amount of work and cost it would take to put in production. On the other hand, fitting a turbo to the 4 cylindr engine was a completeley differnt thing and gave better results, the rest, as they say, is history.

JamesF
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Post by JamesF » Tue Nov 25, 2014 7:38 pm

The pumps were still set differently on the turbo engine.

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bedwards1966
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Post by bedwards1966 » Tue Nov 25, 2014 8:00 pm

They would be. Add a turbo to increase the air and you end up with a lean mixture. This is fine for the OP as he is just looking for a cleaner burn which will be achieved.
But for increasing power if you have more air you add more fuel to make use of the extra air.

Guest

Post by Guest » Tue Nov 25, 2014 8:08 pm

They were calibrated slightly differently to balance the fuel/air mix but the increase in the delivery of fuel was to give a 'richer' mixture, the amount of injected fuel needs to be proportional to the amount of air for efficient and smooth combustion, that's where the increase in power comes from opposed to a naturally aspirated engine. Introducing as cold air as possible also increases the compression, that's where an intercooler helps.

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ollek
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Post by ollek » Tue Nov 25, 2014 8:16 pm

The fuel is sprayed into the cylinder at the end of the compression stroke. There is no air/fuel mixture in the cylinders when the piston is rising during the compression stroke, only air that gets so hot that it will ignite the fuel that is getting into the cylinder via the injector. A turbo will press more air into the cylinder, making it possible to spray more fuel in at the end of the stroke and the larger amount of oxygen will be able to burn more fuel. This gives you more power because the larger amount of fuel will create more pressure on top of the piston. Cold air will not increase the compression, but cold air is holding more oxygen per volume and is therefor able to burn more fuel. The air is a gas that expands when the temperature is rising, as all materials do.

JamesF
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Post by JamesF » Tue Nov 25, 2014 8:53 pm

Iv just watched the YouTube video posted by th OP. I have to admit the engine sounds really sweet!! Almost worth it for that alone!

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nick885
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Location: sark,channel islands

Post by nick885 » Tue Nov 25, 2014 9:45 pm

Hi all, I am pleased to see this topic being discussed as it is my DB 885N with the turbo fitted that is in the video clips. This was a little project that I wanted to try out after reading about DBT experimenting with a turbo fitted to the three cylinder engine.
I can confirm that the power increase is not that much but it dose seem to burn cleaner when under working load. The max boost pressure is about 5 psi and it runs really well. I was also wondering what the boost pressure was for the four cylinder engines.

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machine_gun
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Joined: Sun Mar 16, 2014 12:48 pm
Location: Telford

Post by machine_gun » Tue Nov 25, 2014 10:16 pm

Nick885, wery glad to hear from you that it is working well. I did try to contact you on FB and Gmail quite long time a go by asking how does your 885 doing after while and did you observe any problems. Sorry for that stalking :D but your 885N turbo really turned my mind to fit one on my 780.

jazo
Posts: 805
Joined: Fri Jun 15, 2007 7:13 am
Location: New Zealand

Post by jazo » Wed Nov 26, 2014 9:22 am

Hi. My 1394 was about 7 psi and a 1494 I have tested was about 12psi. 1410/12s would be more though!
1694 4wd
1394 4wd
1294 4wd
30D
990x2
880
780x2
900

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richbug
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Location: Pennsylvania, United States of America

Post by richbug » Wed Nov 26, 2014 12:12 pm

jazo wrote:Hi. My 1394 was about 7 psi and a 1494 I have tested was about 12psi. 1410/12s would be more though!
Both 1394s here run 10psi when working at full load. My 1494 will peak at about 12psi.
Users: 780, 1210 Bottle Opener, 1494 4wd open station with 74L, 990, 1394, 1194 High Clearance, another 1394, 1194 LCG, 1290 with 56L, 900, 885 with LS8, 885, 1190

1200, 900 projects, 780,

Parts: 3800, 1200, 1394, 1412, 1490, 770, 885, 990SEL, Red 990I,

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erkki
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Location: North Finland

Post by erkki » Wed Nov 26, 2014 1:38 pm

double posted
Last edited by erkki on Thu Nov 27, 2014 6:01 am, edited 1 time in total.

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erkki
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Post by erkki » Wed Nov 26, 2014 1:39 pm

I think 1394 has the NA -type crankshaft with smaller dia on mains. It would not be any problem to pull out 90 hp from that engine but probably it will put the crank to try hard. I have an impression that turbo on 1394 was more or less in order to enhace fuel economy and perhaps also to clean the exhaust.

There is a small difference in timing between NA and turbo engines and if I remember correct, the charged have a few degrees less advanced injection. Somebody knows better.

Putting a turbo to a three potter cant be a big problem. Several years ago Tractor News could tell about a DB man in Australia, who rebuilt an 880 for light contracting. They added a turbo there and adjusted the engine output to 67 hp. I am not surprised if the tractor still runs.

RGDS erkki

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richbug
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Joined: Mon Mar 22, 2010 5:32 pm
Location: Pennsylvania, United States of America

Post by richbug » Wed Nov 26, 2014 9:10 pm

erkki wrote:I think 1394 has the NA -type crankshaft with smaller dia on mains.
Smaller mains and rod journals... same as a 1200/1210.
Users: 780, 1210 Bottle Opener, 1494 4wd open station with 74L, 990, 1394, 1194 High Clearance, another 1394, 1194 LCG, 1290 with 56L, 900, 885 with LS8, 885, 1190

1200, 900 projects, 780,

Parts: 3800, 1200, 1394, 1412, 1490, 770, 885, 990SEL, Red 990I,

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