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Tuning with oxygenated fuel

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Tuning with oxygenated fuel

Postby D.Cecere » Mon Oct 19, 2009 7:41 am

Hi all,

Was just wandering what people's experiences are out there when replacing regular fuel with a racing oxygenated fuel.
Will increasing the jet sizes be the only modification required to compensate for the oxygen in the fuel?
Do you still aim for the same a/f ratio?
What power benefits can be expected?
"Finding horsepower is an addiction"
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Postby W. Tripp » Mon Oct 19, 2009 9:26 am

Different fuels act in different ways, this is no different with oxygenated race fuels. Some of these fuels require different amounts of fueling, and ignition advance compared to others - there is a large range of differences in these fuels.

So it all depends on what fuel you are running now, and which oxygenated race fuel you are considering.

Generally, using a Lambda sensor, you can expect the oxygenate to alter the reading from true Lambda/AFR. But if you start rich and tune to max brake torque (MBT) or best track results, you can get best results with or without a Lambda/AFR meter.

edit: Benefits - I've run fuels oxygenated anywhere from 4-12%, including fuels from VP, R-Tech, XXX, Power-Mist, etc. Some fuels add nothing. A few give as much as 4% comparing peak to peak, with as much as 6% either side of the peaks. The fuel used needs to be matched to the needs/use of the engine.

Be aware that some of these fuels are corrosive, and should not be left in the fuel system overnight.

I hope this helps.
Last edited by W. Tripp on Mon Oct 19, 2009 10:46 am, edited 1 time in total.
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Postby robert1 » Mon Oct 19, 2009 10:00 am

Word of warning I wish I had known about. I have one guy that was running this. I posted last fall about having problems with ex valves falling off. They all happened with one customer all different brands. I am working through one right now with Xceldyne. We disscussed my spring setup and other characteristics of the valve train. While he said my setup might not be optimal it wasn't what was causing the valve failures. Then we disscussed timing, a/f ratios, and Bsfc numbers. As we talked we ran into egts. I had just run a competitors engine and it had the same egts as mine so I wasn't concerned about them although I thought they were a little high. They were around 1420° at 8,000 and climbing but I didn't pull any higher as I didn't need to. As the other motor was doing the same thing I wasn't too alarmed. Xceldyne pointed out this was way too high and would be the cause of my problems. I then did some checking and the annealing temp for Ti starts around 1450°. So you've be warned procede at your own risk. A side note, I thought these were Xceldyne valves when I sent them back for inspection. He called me Fri and asked what brand these were, I'm thinking "dumba__",me. They weren't Xceldynes and they still took the time to evaluate them. The customer service at CV Products is second to none in my book.
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Postby bigjoe1 » Mon Oct 19, 2009 10:50 am

My own expeeriance with Q 16 has been you go up five sizes on the main jets and it will work REAL good. I have seen up to 30 HP increase over C-14 with no other changes. This was .14 hundtreds and 1.5 MPH in a drag car with the fuel change alone. I have not seen anything about the exhaust valves or whatever.


JOE SHERMAN RACING ENGINES
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Postby David Redszus » Mon Oct 19, 2009 12:18 pm

Whether or not a fuel contain an oxygenate does not really matter.
What really does matter is the stoich value for that particular fuel.

A fuel blender can counterbalance the addition of an oxygenate with a component that has a high stoich value so that the net stoich value of the fuel remains unchanged.

The stoich value of a fuel (like octane value) cannot be considered in isolation. What is equally important are vapor pressure, distillation curve, heating value, evaporation, etc, etc.
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Postby W. Tripp » Tue Oct 20, 2009 7:13 am

David Redszus wrote:The stoich value of a fuel (like octane value) cannot be considered in isolation. What is equally important are vapor pressure, distillation curve, heating value, evaporation, etc, etc.


The problem is getting accurate and complete data from the fuel blender. Some of this is hard to come by - especially the stoich value. Some blenders share this, others do not.
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Postby David Redszus » Thu Oct 22, 2009 12:18 am

W. Tripp wrote:
David Redszus wrote:The stoich value of a fuel (like octane value) cannot be considered in isolation. What is equally important are vapor pressure, distillation curve, heating value, evaporation, etc, etc.


The problem is getting accurate and complete data from the fuel blender. Some of this is hard to come by - especially the stoich value. Some blenders share this, others do not.
That is easily done. Simply ask for the carbon/hydrogen/oxygen ratio for the fuel, or in the alternative, the DHA for the fuel. Good luck. :D

The reason the information is difficult to obtain (even if the blender actually knows what it is) is because it often varies from fuel batch to batch, even for a single blend.

For a moderate sum of money, a fuel sample can be sent to a lab for analysis. The cost is typically under $300 which could be shared among several racers. Then you could sell the information back to the fuel blender. :D



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