NZ951

As topic, in line fuel radiator... they look interesting.

ehall

can't think of a large enough benefit to performance, as your fuel lives in the tank at the rear. I think you're much better off staying with the concept of cooling the charge air. Unless you plan too run your fuel through an a/c unit similar to a U.S. style beer tap, I can't see enough benefit. Just my take.

Charlotte944

Back in my muscle car days we used to turn 3 lb coffee cans into fuel coolers.

Basically we would bend some metal fuel line into a coil, mount the coil inside the coffee can, and then connect it to the fuel inlet to the carb.

For racing just pop the plastic top off, throw in some dry ice, put the top back on, and have at it. BTW: We punched a small hole in the top to let CO2 escape.

Bill

I agree with ehall and expand.

This old trick has been used to add a small increase in performance to normally aspirated race cars. It made a performance increase to strictly regulated race class vehicles. What it does is to make the fuel charge more dense, thus adding more fuel molecules and achieving a richer charge. Basicaly like adding a larger carb.

But is should make no performance change to a computer controlled turbo car. With high boost, the turbo crams so much air into the cylinders that you must dump gobs of fuel to match. We are talking big injector size changes not just a little denser fuel mix. On the smaller scale that is a denser fuel mix, the computer compensates via the barametric, air temp, O2 sensors to not allow a slightly richer mix. Just as close to a perfect mix as possible.

If any impact is seen, a cooler intake charge would help with detonation. But you would get better bang for your buck by getting a larger intercooler or water to air intercooler. Just remember, with high boost, it is the compressing of the air in the turbo where you get the high heat gain. So it is the air charge that you want to remove the heat from. The fuel is injected just behind the valve so it has very little time to affect cylinder temps.

ehall

Cliff, that's awesome. What a good idea. That cracks me up. KISS right? ! lol

Bill

KISS.......Keep It Simple Stupid!

I learned that saying in my very first automotive repair class and have heard it in every one since. It remains my favorite automotive saying, ever. It is so true.

NZ951

WHy not have more dense cooler fuel which is kept at the same AF by the computer? Surely cooler fuel is better...

Charlotte944

Doesn't make any difference. The DME has no idea how much fuel, either hot or cold is flowing. The DME polls the O2 sensor and based on the engine load signal from the AFM, adjusts injector duty cycle (open/closed timing) to maintain a 14.7:1 A/F ratio.

In this scenerio, with "colder" fuel the injectors are open for a shorter period of time than for "hot" fuel. This is purely a result in the difference in fuel density between "hot" and "cold" fuels.

The reason fuel coolers work with NON FUEL INJECTED cars is because the fuel metering is purely mechanical and is controlled by the size of the jets (orfices) in the carb's metering body. A given sized jet will flow a given amount of fuel at a given pressure and temperature. There fore, for a given jet size, a "colder" fuel will cause the A/F ratio to be more rich than a "hotter" fuel. Its all a matter of physics.

NZ951

I have a Link standalone... no DME.

So I can reduce the duty cycle of the injectors, thats a bloody good thing. I can reduce the pulse width and have a greater capacity of my injectors. Not to mention the reduced temperature in the combustion chamber...

Tom M'Guinn

Of course, at WOT, the O2 signal is not used to adjust fuel.

Also, I'm no expert, but just speculating on a Sunday afternoon...

Even if you have to dial in shorter duty cycles for the cool fuel, I imagine a short quirt of cool gas is less likely to pre-ignite than a longer squirt of hot fuel.

I have no idea how hot the fuel gets in a 951 though -- the long fuel lines and big tank would seem like pretty good coolers to start with, no?

The old carb motors used to have fuel sitting in the lines under the hood waiting for room in the float bowl. That left lots of time to heat up and nothing to cool it off -- hence "vapor lock" and efforts to cool fuel for more performance.

NZ951

Tom,

The issue is that the returned fuel is heated, a lot. It goes up the fuel line, over the exhaust, into the fuel rail, then back to the tank, so the return line fills the tank constantly with hot fuel, so, you would want to add the fuel radiator on the return line, so the tank does not get filled with hot fuel...

hosrom_951

Both supply AND return fuel lines get hot, since they are over the headers, that is where thermo-sleeves come in and help in keeping the heat away (but it is still hot). Next issue is the fuel rail itself, try touching it, it is hot.

If you add a fuel cooler and keep the rail and lines the way they are, the temp. drop would not be so great, you still have that hot fuel rail. Adressing the lines and rail first would be more effective, offcourse all three together (fuel rail, lines and cooler) would maximize the cooling.

ehall

So...
How much cooler must the fuel be to get targeted performance improvement?
How much will the new set up weigh, and how much of that weight will be offset my additional hp and/or lost because of additional weight?
Is the overall gain enough to make the weight/ time/ cost/ performance worth it?

All those in mind...I would want say...the potential to safely run atleast 1 psi greater boost without detonation.
That too me would mean a gain derived strictly from the mod alone.
What's 1 psi worth? 15-20 hp? I really don't know.

Charlotte944

You guys just don't get it: A fuel cooler IS NOT going to do you any good, so don't waste your time and money.

However, there is a problem with the fuel line route over the headers, and wrapping the lines is done to protect the fuel lines, and not to keep the fuel cool.

ehall

seems to me that only one guy is even considering it. The rest of us are just asking questions that may help the guy figure out if this is even remotely worth the effort/expense.