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‘05 749R, ‘89 851/926, 749R/999RS project
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I'm a bit suss on the twin turbo setup. The super-experienced crew at Ducati Bunbury have done the hard yards for you, and tried exactly that:
Prototype:
988269


Only to find it just didn't produce the goods, and going for a single turbo set-up instead. This is an older article but gives you an idea of some things to look out for:
Stretched custom Ducati 749 turbo dragster - Bike Review

988271


Todd/Wayne absolutely know their shit with the fastest 2 valve Ducati in the world (turbo'd) before moving on to the 4 valve 749R. I try to do as much of my work as possible but if I need some assistance these are the guys I go to (2 hours South vs local Ducati dealer), genuine enthisiasts and top blokes.
 

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Discussion Starter · #23 ·
Helge and seven4niner, thank you both! I had not seen the video and if you pay attention it really provides a bunch of data and specifics about differences between an S and a full on Factory bike. I am researching the work by Ducati Bunbury too. It’s much cheaper and faster to learn for those who went before. Thank again guys it’s much appreciated.
 
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Discussion Starter · #25 ·
As I continue the build....I would love some input on the throttle bodies, especially the shower injectors. I plan on boring the throttle bodies to the largest opening I can manage. After reading Shazam’s article on filters where he mentions even a finger near the velocity stacks will drop power as the flow into the heads is disrupted. This has me thinking those injectors and bars holding them over the velocity stack is hurting top end HP....so I was thinking about building a spacer between the throttle body and head and inserting injectors there. Now since this is going to be a turbocharged motor would the flow disruption make a difference? Thoughts? 1 advantage is it’s much easier to seal the plenum without injector lines passing through.
 

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‘05 749R, ‘89 851/926, 749R/999RS project
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I’m not sure a blade supporting the injector is really an issue, but you could always do it “1098-style” and mount the injectors in the roof of the plenum (1098 has injectors mounted in the airbox lid)
 

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Discussion Starter · #27 ·
While that’s easy especially trying to seal the plenum, do you think the air blowing in from from the turbos will effect fuel distribution? I would think it will as it comes up on boost unless the injectors are so close over the top of the stacks....but them back where we started. Will the injectors directly over the velocity stack hurt top end. Remember we are looking for Sustained max RPM power.
 
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‘05 749R, ‘89 851/926, 749R/999RS project
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While that’s easy especially trying to seal the plenum, do you think the air blowing in from from the turbos will effect fuel distribution? I would think it will as it comes up on boost unless the injectors are so close over the top of the stacks....but them back where we started. Will the injectors directly over the velocity stack hurt top end. Remember we are looking for Sustained max RPM power.
I wonder if you are confusing air flow with air pressure? It’s not like the injectors are sitting in the middle of a large pipe wirh air rushing past them, they are basically in an open chamber at a dead end.

The whole idea of the airbox/plenum is that it is a pocket of still air that is pressurised by either ram-air or, in your case, a turbo.

So you have your plenum pressurised to, for example, 15psi, and your intake valves just take bites of that pressurised air with the injectors adding fuel as required. More air (pressure) = more fuel = more hp. Most of the Brayton Cycle ( suck, squeeze, bang, blow) the intake valves are closed, so there is no air in the plenum rushing anywhere.

But, the limit you run into is that compression = heat. Heat = less dense air. So intercooling becomes critical. Past certain boost you can literally end up chasing your tail to achieve bugger all except make more heat.

Sorry, don’t mean to tell you how to suck eggs.
 

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While that’s easy especially trying to seal the plenum, do you think the air blowing in from from the turbos will effect fuel distribution? I would think it will as it comes up on boost unless the injectors are so close over the top of the stacks....but them back where we started. Will the injectors directly over the velocity stack hurt top end. Remember we are looking for Sustained max RPM power.
I would say there is reason why pretty much all high power engines use injectors over intake trumpets. MotoGP, F1 etc. Well F1 uses direct injection now, but that is because they are trying to get emissions down and other bullshit like that. And even new Ducati engines use over trumpet injectors, so it is good way to do it.

This is from one F1 article:
"with so called "Shower Injectors", with injectors located before intake trumpets. You can actually see injector spray. This arrangement allows fuel to be sucked with air inside cylinder. When you mount the injectors further away from the combustion chamber you have a more efficient air/fuel mixing effect and additional cooling effect. The cooler the intakes charge the better combustion and less pre detonation. And that will result in more power. Trade off is less fuel efficiency, but more power with proper combustion. "

 

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Hypermotard 1100 EVO SP Corse
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Well F1 uses direct injection now, but that is because they are trying to get emissions down and other bullshit like that.
Direct injection is cool and all, but the real benefits come from stratified direct injection, this allows the injector to deliver a rich mix immediately before ignition, and then once it's burning, continuously lean the mixture out.

Yes, you gain reduced hydrocarbon emissions, but the most important "other bullshit" that comes with this is the leaner burn when the rod journal is perpendicular to stroke, so initially you get a rich enough charge to ignite when the rod is at a small angle, but more powerful force on the piston from lean burning when leverage on the crank is at it's highest.

not that this has any bearing on a stock class bike, but its pretty cool
 

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Discussion Starter · #31 ·
Haven’t posted any pictures of progress. Mocked up before tear down for paint.
1005103
 

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Discussion Starter · #32 ·
Frame painted...
1005104
 
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Discussion Starter · #34 ·
Yes! Everything but the color. Was thinking about a set of slip ons,(turbos) 🧐
 
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Discussion Starter · #35 ·
A beer fueled night of welding. Friends don’t let friends drink and weld 😁. Trying to satisfy the FIM rules about sweaged fittings. Had to weld up all the turbo fittings. And finished up the exhaust.
1008991
 
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Discussion Starter · #36 ·
Made a hell of a mess in the garage though.
1008992
 

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'06 S2R 1100 Custom, '12 SF 1040
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Beautiful welding by the way, it’s inspiring me to increase my skills 👌🏼
 

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Discussion Starter · #39 ·
A couple of wee updates. Working on the wiring now. 60 f-Ing pin ECU harness….bloody lot of wires.
1012311
1012312
 

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Discussion Starter · #40 ·
The LS2 boys came through and were able to get FIM homologated helmets in for us…it’s taken over a year to get..,, and I must admit, it’s damn fine helmet. I think I might just switch my street helmet (Arai) to an LS2 as well. So far very impressed.
1012313
 
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