Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 998 / 996 / 916 / 748 > Headwork, gasflowing

[flyingbanana]

:P Hello chaps and laydeees. Having some gasflowing work done soon. Was wondering what improvments and gains others have seen if they had before and after runs done etc. My 54mm system is dying to breath at the top end you can see on the graphs where it just sort of goes limp, doesn't tail off but just levels off the rest of the way to the limiter. Plus comparing figures with other 853 owners running different exhausts but all having blueprinted or flowed engines this appears to be the only reason for the power deficit. opinions welcome.

all money no sense

[Desmondo]

What sort of money we looking at to get this king of work done?

[Shazaam!]

It's good that you're being cautious here.

If I had to guess what section of the engine that Ducati spends the most time and money on - engineering, dyno development and racetrack testing combined - I'd pick the cylinder head. This is where combustion chamber shape, valve technology, ignition, and air flow optimization takes place and it is the key component to more engine power.

Unlike earlier engines, current head designs are the culmination of previously unavailable computer-based analytical techniques and sophisticated test equipment combined with current race track experience. In days past, engine design and manufacturing techniques were quite crude so when performance increases were in order, porting and polishing were an effective hot-rodding technique to create smoother and more complex intake and exhaust tract shapes than mass production casting techniques allowed.

With today's casting technology, there's very little to be done, or gained, in smoothing the intake and exhaust tracts since the real constraint on air flow into and out of the engine is the valve number, diameter, lift, and opening duration. A mirror-smooth port can even reduce efficient mixing of the incoming fuel and air.

Using a flow bench to improve flow rate by making gross or subtle changes to the contour of the inlet and outlet tracts is an entirely different matter. In this instance you're betting (your cylinder heads) that the machinist knows more about compressible gas flow and vortex-induced fuel-air mixing theory and practice than Ducati experts. You're also betting that he gets an improvement without benefit of any dyno development work.

There are still some practitioners of this labor intensive (i.e. expensive) craft however, and armed with a flow bench that clearly shows an improvement in air flow through a cylinder head (without valves, I might add) there are still plenty of customers who buy the story that increased air flow to and from the valves will give them more power.

Frankly, I wouldn't let anyone take a grinder to my engine before seeing a before-and-after dyno chart of - just the gas flow modification - on an identical bike.

[skidlids]

Out of interest FB what size injector bodies are you running. I recall reading about the early 748 ones being restricted. May be more to be had in this area.

[Nigel Booker]

Read somewhere that its not really worth spending a lot of time and money on blue printing and gas flowing the heads on ducatis as the factory produced item is of such a high quality.

Not my opinion just what i've read ok.

[flyingbanana]

Throttle body size. Dunno what it is but it's still standard 748sps. Weeksy's about right on the costs involved but shopping around is always the option as different tuners add different aspects to the work as in Alan's case where he'll service the bike at the same time and you'll pay a bit less for the two combined pieces of work. I've been reliably informed that I should see reasonable gains with the work, which i'm mostly doing to maximise the use of my 54mm system, which is being somewhat wasted in the current state of tune. Yes Shazamm is right, one again that previous engine mods surrounding head work on older engines would have seen greater benefits and that current technologies allow for greater accuracy and consistency. But what it comes down to is the fact that all the bikes we ride when they come off the production line are built to a compromise, both in terms of engine tune and components. if every bike was a 996r we'd be selling our wifes and body parts to ride the things. When making substancial changes to any aspect of an engines characteristic there will be trade off's as Alan likes to say. one of these is reliabilty the other for me is rideabilty. My 54mm system would have ridden like a devil in about 2000rpm of my sps's rev range and not at all anywhere else, solution more cc's more gas. Healthy power increase. Now the knock on effect is the standard heads don't flow enough or 'efficiently' enough with the given tune and system, solution alter the cylinder head to match the demands of the system and hopefully release more ponies. We will have to wait until it's down before we can start crying or singing. I'll let you know