Hot fuel effect

[Vince]

Just watched a TV show called engine master, all big V8s on Dinos. They were looking at how heat affects engine performance. First, they added heat to a base test, applying hot air guns, and there was no measurable effect; made me happy in a country that can get bloody hot. Next was reducing heat by adding ice bags to the inlet manifolds as you see drag racers do, and surprisingly that also had no effect. Next they tried ice bags on the carby, and that made a significantly measurable effect, upping power, and that surprised them all. Now to bikes, you see race bikes getting their fuel tanks covered by what looks like an insulated blanket on the grid. They used to chill the fuel in the old Castrol 6hr, but from what I remember that was to reduce fuel expansion so they could get as much fuel into the tank for range. Lots of bikes these days get under-tank insulation from the engine; I thought to avoid melting modern plastic tanks. Might be worth looking at this on race bikes. Fuel sitting right on top of hot engines. I used a bunch of stick on heat reflective alfoyal tiles on the back of the plastic side cover on the Atlas so it wouldn't melt, might get some for under the fuel tank as well.

 

[piranha-bro2]

I think cooling the inlet air is the trick - intercoolers - but maybe only with EFI? Running pre-carb/EFI intake air through metal tubes in the fuel tanks (ZXR Kawasaki) also a way to do it. Definitely notice how crisp a motor feels on a cold clear night (or day).

 

[Alzero]

Engine Masters is hands down the best automotive tech show ever made. The dyno does not lie. I’ve seen every episode, some twice!

 

[Dellortoman]

Lots of bikes these days get under-tank insulation from the engine; I thought to avoid melting modern plastic tanks. Might be worth looking at this on race bikes. Fuel sitting right on top of hot engines. I used a bunch of stick on heat reflective alfoyal tiles on the back of the plastic side cover on the Atlas so it wouldn't melt, might get some for under the fuel tank as well.

G'day Vince

In the Kawasaki Z1300 community, vapour lock in the fuel injector pump can be an issue in hot weather. That bloody big, wide, heavy engine with 6 exhaust headers is a massive source of heat. When riding one on a warm day in stop-start traffic (eg. city commuting) it feels like you're sitting on a volcano. While stopped at traffic lights, you get cooked by the hot air wafting up from the engine. The fuel tank (and the fuel in it) can get surprisingly hot. It doesn't help that the default colour for the tank on those bikes is black, so on a sunny day it'll also absorb solar radiation.

Insulating the underside of the fuel tank is a common modification among Z1300 owners, especially in warm climates. The insulation of choice is reflective air-cell foil. It's the stuff that looks like bubble wrap with a layer of foil on both sides. Not the sound insulation stuff for cars because that has a dense foam in it that's not as good a thermal barrier as air pockets.

I never got around to doing it on my Z1300 because the climate in Tassie is cool enough that vapour lock isn't a regular issue, although it has happened to me on a couple of occasions. If I had some of that air cell foil lying around I'd definitely stick some of it on the underside of the Kawasaki tank.

There are a bunch of different manufacturers who supply the air cell foil to the building industry. But for insulating a bike tank, the issue is getting it in a small enough quantity. You only need a couple of square feet so you don't want to spend hundreds of bucks to buy an industrial sized roll of the stuff. However, there's a thermal insulation foil you can get for garage doors (link below) that comes in a smaller quantity than the the usual building insulation rolls. It comes in a 6 m2 roll (5m x 1.2m) for around $60 which would be enough to do a dozen bike tanks. If you bought a roll you could do all of your bikes and still have plenty left over to give to your mates

Cheers,
Cam


Garage door insulation:

https://www.ebay.com.au/itm/167370068545?chn=ps&_ul=AU&_trkparms=ispr%3D1&amdata=enc%3A1_cYirO6CQnCUe9TnzY2_CA44&norover=1&mkevt=1&mkrid=705-173151-935305-0&mkcid=2&mkscid=101&itemid=167370068545&targetid=2367800370202&device=c&mktype=pla&googleloc=9072355&poi=&campaignid=21776442415&mkgroupid=173963205248&rlsatarget=pla-2367800370202&abcId=10047386&merchantid=119391545&gad_source=1&gad_campaignid=21776442415&gbraid=0AAAAAD97CxS1VMb_Ob_B_oEEY93DfaqWd&gclid=EAIaIQobChMI9YST8OTilQMVZoRmAh1AchSjEAQYBiABEgK2DfD_BwE

 

[Vince]

This is the stuff I used on the Atlas plastic sidecover; it ended up costing approx $100 with that pretty big sidecover. Cheaper than melting a hard to find replacement.

https://www.mxstore.com.au/p/CPR-200x360mm-Stick-On-Muffler-Heat-Shield/60-152-MS1

 

[Laverdalothar]

For Cars, you can buy Water injection systems to up the HP:

 

[Alzero]

When you went to War Emergency Power on an Allison and I believe a Merlin, you activated the water injection system. It was mixed with methanol to prevent freezing. One reason the pilots were supposedly time limited at that power setting was that it quickly ran out. Of course in a true War Emergency nobody cared!

 

[Andy]

When you went to War Emergency Power on an Allison and I believe a Merlin, you activated the water injection system. It was mixed with methanol to prevent freezing. One reason the pilots were supposedly time limited at that power setting was that it quickly ran out. Of course in a true War Emergency nobody cared!

A friend of mine was in our air force as an aircraft mechanic, when we had Andovers which could manage a very short takeoff with the aid of water injection. After every two aided takeoffs, the engines had to be overhauled, which wasn’t popular. He described the engines as being “designed by someone who started with the single bolt that needed to be removed most often, then they built the rest of the engine around it”.