Fuelling - the factory's response
Discussion
In conversation with Richard whilst organising the final bits for my car, he and Ted have been interested to read the threads regarding fuelling. To this ends, they've asked me to post the following:
The Editor of Piston Heads
I wonder if you could post this reply to a query from a customer made in response to the current discussions about fuel pipe sizes.
It is not the policy of Ultima Sports to reply to every topic raised on the forum as we are delighted that the Ultima does generate all this interest and we do not want to stifle a healthy debate.
However this topic more than any other has caused a lot of customers some considerable concern and I want to reassure builders that the company has extensively researched and tested the fuel system at considerable expense and that the current fuel system when fitted to the instructions on the manual CD will not damage their engine.
Thanking you in advance
Ted Marlow
Managing Director
Ultima Sports Ltd
David
I am delighted that you have asked the factory about the fuelling on the Ultima so that at last I can answer the questions and respond to the false rumours and resulting concerns that have been circulation on some forums.
There has been a lot of discussion about pipe sizes, rule of thumb, engine failures etc etc.
Without going into the detail of years of experimenting and test results on this issue which could fill a book the very brief answer is-
Irrespective of any of the above, the fundamental issue is the amount of fuel available at the point of entry to the carburettor compared to the amount of fuel the engine uses at full power.
Unlike practically any other car, the fuelling system on an Ultima is relatively short with the pumps and fuel tanks actually alongside the engine. This means short fuel lines with correspondingly low friction losses and less mass of fuel vulnerable to "g" forces
If an Ultima was a front engine car with a rear fuel tank which required another 20' of hose for instance this might be different.
In the past 18 years, every combination of fuel pumps, surge tanks, pipe sizes, electronic valves has been experimented with and extensively tested in the Ultima and yes, along the way the company has had expensive failures which we do not want our customers to experience.
I am constantly dismayed when I find that a customer has wasted all this expensively gained research and experience and innocently used a different system to the factory version, which was in most cases discarded years ago for very good reasons. Hopefully it will not cost him the tens of thousands of pounds that it has cost the factory to find his mistake.
However we are all still learning and the fact that some builders are contemplating fitting engines of over 650 bhp has reopened this issue.
To this end our latest demonstrator, which has a load of experimental parts fitted that are there to be evaluated and extensively tested by the factory, as part of our ongoing development programme before general release, has been fitted with -8 pipes and fittings in order to measure the all important fuel delivery at the carb, so that a system can be developed for these higher horsepower engines.
Initial findings are that the difference in fuel flow at the carb between -6 and -8 pipes is not significant but, the main restriction to flow is the crude proprietary fuel pressure regulator- I could go on for another couple of pages on this issue alone so I will not bore you any further.
Basically- in answer to your original question-
1/ No American speed Engine has failed due to the size of the fuel pipe.
2/ A couple of factory built Ultima GTR's experienced engine failure due to a complicated experimental fuel system that is obviously no longer used
3/ The fuel system size on the Ultima is -6 for engines up to 650 bhp
4/ The fuel pump system pictured in the Can-Am and GTR CD works.
5/ American Speed approves of this set up.
6/ All five company demonstrators use this system with engines up to 590bhp.
7/ If any other engine manufacturer is used, ask him what fuel flow his dyno shows the engine to require at full power and to contact Ultima to confirm if the actual fuel flow has a sufficient factor of safety.
Kind regards
Ted
The Editor of Piston Heads
I wonder if you could post this reply to a query from a customer made in response to the current discussions about fuel pipe sizes.
It is not the policy of Ultima Sports to reply to every topic raised on the forum as we are delighted that the Ultima does generate all this interest and we do not want to stifle a healthy debate.
However this topic more than any other has caused a lot of customers some considerable concern and I want to reassure builders that the company has extensively researched and tested the fuel system at considerable expense and that the current fuel system when fitted to the instructions on the manual CD will not damage their engine.
Thanking you in advance
Ted Marlow
Managing Director
Ultima Sports Ltd
David
I am delighted that you have asked the factory about the fuelling on the Ultima so that at last I can answer the questions and respond to the false rumours and resulting concerns that have been circulation on some forums.
There has been a lot of discussion about pipe sizes, rule of thumb, engine failures etc etc.
Without going into the detail of years of experimenting and test results on this issue which could fill a book the very brief answer is-
Irrespective of any of the above, the fundamental issue is the amount of fuel available at the point of entry to the carburettor compared to the amount of fuel the engine uses at full power.
Unlike practically any other car, the fuelling system on an Ultima is relatively short with the pumps and fuel tanks actually alongside the engine. This means short fuel lines with correspondingly low friction losses and less mass of fuel vulnerable to "g" forces
If an Ultima was a front engine car with a rear fuel tank which required another 20' of hose for instance this might be different.
In the past 18 years, every combination of fuel pumps, surge tanks, pipe sizes, electronic valves has been experimented with and extensively tested in the Ultima and yes, along the way the company has had expensive failures which we do not want our customers to experience.
I am constantly dismayed when I find that a customer has wasted all this expensively gained research and experience and innocently used a different system to the factory version, which was in most cases discarded years ago for very good reasons. Hopefully it will not cost him the tens of thousands of pounds that it has cost the factory to find his mistake.
However we are all still learning and the fact that some builders are contemplating fitting engines of over 650 bhp has reopened this issue.
To this end our latest demonstrator, which has a load of experimental parts fitted that are there to be evaluated and extensively tested by the factory, as part of our ongoing development programme before general release, has been fitted with -8 pipes and fittings in order to measure the all important fuel delivery at the carb, so that a system can be developed for these higher horsepower engines.
Initial findings are that the difference in fuel flow at the carb between -6 and -8 pipes is not significant but, the main restriction to flow is the crude proprietary fuel pressure regulator- I could go on for another couple of pages on this issue alone so I will not bore you any further.
Basically- in answer to your original question-
1/ No American speed Engine has failed due to the size of the fuel pipe.
2/ A couple of factory built Ultima GTR's experienced engine failure due to a complicated experimental fuel system that is obviously no longer used
3/ The fuel system size on the Ultima is -6 for engines up to 650 bhp
4/ The fuel pump system pictured in the Can-Am and GTR CD works.
5/ American Speed approves of this set up.
6/ All five company demonstrators use this system with engines up to 590bhp.
7/ If any other engine manufacturer is used, ask him what fuel flow his dyno shows the engine to require at full power and to contact Ultima to confirm if the actual fuel flow has a sufficient factor of safety.
Kind regards
Ted
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