E85 Lift And External Pumps

[Duncan]

Hmmm I realized after the recent replies that I never came back with my plans; I've stuck with my current setup (lift pump + 040) and will run the additive when (if?) I run e85. I just couldn't find an e85 external pump that I could use without changing the otherwise excellent external surge tank, and I don't have a particularly large fuel requirement as it's a production car.

BTW Mick I was also intrigued about your statement that it is the engine/fuel rail that warms up fuel, I always assumed it was running fuel through a pump that warmed it. So I ran fuel through a pump and back into a tank (not via a running engine) with a pump at full noise for 20min and the fuel heated up by 10o over ambient, ie stuff all. I've never tested fuel temps circulating through a running engine so I don't know how that would compare to 10o.....I also don't know exactly how temps affect fuel (either by reducing octane or oxygen %) so I don't know if 10o is even relevant; I guess not....

[GTSBoy]

A pump running with little back pressure heats the fuel a lot less than one running against a head.

The trip through the fuel rail definitely adds heat. Running more fuel through the rail and back than is strictly needed will pull more heat out of the bay and into the tank, even though the heat transfer limitation is actually on the outside of the rail.

Hot fuel detonates more easily. It consumes less heat out of the charge air that it is injected into when evaporating, so does less cooling. it is also less dense so you can get leaner mixtures, although one would have to do some calcs to decide if that's real or not, as the viscosity goes down at the same time and the mass flow through the injector will decrease with decreasing density but increase with decreasing viscosity.

[Piggaz]

I know Unigroup had issues on their RX7 racecar a while ago. As the race went on, the AFR's got leaner and leaner. A fuel cooler helped ALOT. It's definitely something to consider.

[Duncan]

yeah I might check it again once everything is back together and running.....I've got a fuel cooler to put on but I've not been able to find hard numbers about either what heat is added, or how that heat affects octane

[[200]]

Where would you mount a fuel cooler on a skyline where it'll get airflow?

[rcs_888]

Funny you mention heating up fuel, im running 98 in my R34 and we were doing a bunch of runs setting up the Haltech and we were getting fuelling issues towards the end of the day, we werent losing pressure etc it actually turned out that the surge tank mounted in the boot would have been nearly 50* i reckon it was HOT! So i ended up getting a P/S cooler and hooking that in the return line from the rail to the surge and that made a huge difference on the dyno so i can only imagine with race pace having the extra air over the cooler how much better it would be?

[Duncan]

I'll be putting the cooler under the rear seat on the passenger side, with ducting to direct air to it, same as the gibson cars had for their transfer case cooler.

I'm just missing any proof it's a good idea

[GTR_JOEY]

I use a nismo as a lift pump, flows plenty and fits in stock cradle.but obviously a bit more expensive. I had it sitting with ethenol for a couple of years and it still pumps fine which is more than I can say for my 2 walbro 400s in the surge tank.

 

I also have a fuel cooler under the car just in from of the diff next to the hand brake line. Isn't massive and I couldn't tell you how effective it is.

 

something I want to figure out ?

[sneakey pete]

put in a pre and post temp sensor guage then. Pretty sure they sell them as all in one units with 1/8npt fittings. just need some trickery to get them in then

 

[GTR_JOEY]

Laser thermometer ??

[Dose Pipe Sutututu]

All flex sensors have built in thermometers

If you're using the Zeixtronic kit, there's an earth trigger you can hook up to say a switch and when you flick it will show you the fuel temp...

[GTR_JOEY]

Very cool, did not know that

[Dose Pipe Sutututu]

use the 0-5v feed to ECU.. log that!

 

[sneakey pete]

Just make sure you verify the ECU wouldn't throw a fit and revert to a 98 map or something though

[Dose Pipe Sutututu]

Feed the ECU digital signal for the flex and 0 to 5V for the fuel temperature.

 

 

[Duncan]

On 7/11/2016 at 9:26 AM, Dose Pipe Sutututu said:

All flex sensors have built in thermometers

If you're using the Zeixtronic kit, there's an earth trigger you can hook up to say a switch and when you flick it will show you the fuel temp...

Excellent info, thanks. Turns out Haltech reads and logs the fuel temp via the e85 sensor so I'll at least be able to collect the data