Wgtn bucket racers that use Avgas

**koba** · 10th April 2008, 07:33

Originally Posted by pete376403

What is the actual C/R? does it really need 100 octane?
(calculating static CR = swept volume (ie volume of the cylinder) plus combustion chamber volume divided by combustion chamber volume) Dont forget with a two stroke effective compression only starts after all the ports are covered by the piston so it will be a lot less than the calculated static CR

Not sure, but F5 dave built it and will probably know.
Probably around (maybe not quite) 15 to one.

Come to the buckets and have a looksie if ya wan't it is a great day out and full of innovation and homebuilt stuff, sounds like you might like it.

It aint a normal H100, It lifts the front in the first two gears even leaning foward a bit...

**Str8 Jacket** · 10th April 2008, 07:47

Originally Posted by koba

It aint a normal H100, It lifts the front in the first two gears even leaning foward a bit...

Uh huh, and you know this *how*?!

**Number One** · 10th April 2008, 07:51

Originally Posted by Str8 Jacket

Uh huh, and you know this *how*?!

Cos he was watching *you* cane it chick

**Str8 Jacket** · 10th April 2008, 07:52

Originally Posted by Number One

Cos he was watching *you* cane it chick

lol, nah, the only time he saw me on the track was when I was passing him after he'd crashed! Though I think I better start hiding the key to the shed! Mwahahahahaha!

**Number One** · 10th April 2008, 07:54

Probably advisable

**CookMySock** · 10th April 2008, 08:06

I got a stock-car racer mate down the road, and he is adamant NOT to use avgas. "Get some proper race fuel", he says. "Avgas is really really hard on engines."

DB

**Str8 Jacket** · 10th April 2008, 08:09

Originally Posted by DangerousBastard

I got a stock-car racer mate down the road, and he is adamant NOT to use avgas. "Get some proper race fuel", he says. "Avgas is really really hard on engines."

DB

aha. My bucket has always been run on avgas since it was built so I shall continue to run it on avgas..... As I have said earlier, I have had some bad luck with bikes and this one is running sweet so I dont wanna change anything or fuck with anything.

**Buddha#81:Me** · 10th April 2008, 10:35

Originally Posted by DangerousBastard

I got a stock-car racer mate down the road, and he is adamant NOT to use avgas. "Get some proper race fuel", he says. "Avgas is really really hard on engines."

DB

WTF.......and ask him what "proper" race gas is? If its so hard on engines I'm not gunna fly on wee planes again because they must be due to start dropping out of the sky soon.

"race gas" is often expired aviation fuel. For that reason I always buy my gas from Garden city Helicopters. If its good enough for a wee chopper its good enuff for a FXR.

**koba** · 10th April 2008, 10:40

naa, you can get propper branded stuff like c16, not the kinda shit that they may sell out of a dodgy old dirtbike shop (that would be expired avgas!) but it comes in 20ish liter tins and different octane ratings from 100 (I think) up to at least 116. I think it is lead free too but its fairly expensive. Hardout rally cars use it. "Elf" may be one of the brands? Im not sure tho..

As with the avgas in stock car thing I think they have to run either straight avgas or straigh pump petrol by their rules, not a blend of both as is common practice with buckets.

**koba** · 10th April 2008, 10:42

http://www.vpracingfuels.com/vp_01_fuels.html

There we go, just an example.

**CookMySock** · 10th April 2008, 11:13

Originally Posted by Buddha#81

WTF.......and ask him what "proper" race gas is? If its so hard on engines I'm not gunna fly on wee planes again because they must be due to start dropping out of the sky soon.

"race gas" is often expired aviation fuel. For that reason I always buy my gas from Garden city Helicopters. If its good enough for a wee chopper its good enuff for a FXR.

He had a 200L drum of it in the corner - completely different shit to avgas he sez, and he will know.

Wee planes and helicopters DO drop out of the sky all the time. Dropped cylinders and valves mainly. Their engines are flamin huge - 150hp Cessna engine is 5 litres !! and they rotate at 2700rpm max, so it's not like they are heavily stressed. They run them rich as fuck also - 75% power on a 150HP engine is approx 30 litres / hour fuel flow. If they don't drop outa the sky, they write-off majorly mega-expensive parts left-right-and-center. Aviation fuel is shit - trust me.

If I was racing a two stroke, I'd use the highest octane pump gas, or FRESH race fuel, and Amsoil 100:1 two stroke oil, but I ain't, and I haven't, so YMMV. Celebrate that you can choose!

DB

**F5 Dave** · 10th April 2008, 12:03

Originally Posted by DangerousBastard

Aviation fuel is shit - trust me.

If I was racing a two stroke, I'd use the highest octane pump gas, or FRESH race fuel, and Amsoil 100:1 two stroke oil, but I ain't, and I haven't, so YMMV. Celebrate that you can choose!
DB

I wouldn't trust anyone who says run it on 100:1 as far as I could spit them. Sorry if that comes across rude but that is foul advice.

Here's the skinny: Av Gas is not the best fuel to run in a race tuned 2 stroke. A proper blended race gas like VP is the best, but there are various types to suit applications.

lets knock this route on the head. Not legal for buckets. (& expensive).

So the choices are pump gas or Av. Our pump gas is pretty average. The old Leaded pumpgas was pretty good, better than Av. Octane isn't the only measure of performance, people struggle with that concept.

When we first went to unleaded many years ago it was dangerous in highly tuned bikes & it varied, meaning if you tuned it to the limit then the next batch was a liability. So we went to Av, whilst not perfect was a damn sight better than the options. 98 has probably got a lot better than used to be but haven't bothered comparing it too closely. Av is safe & certainly isn't 'hard on engines'.

I think I had the H at ~ 14 or 15:1 (full stroke, I don't buy the ports argument as the pipe effectively supercharges the cylinder)
For the slipway with short straights 98 will be just fine. For longer tracks I'd run av as that is what the timing is set up for.

Run 40:1 with a decent oil. Spectro Gold is what it used to run with very low wear rates.

[cue the people who think I don't know what I'm talking about having their rant]. . . now.

**Buddha#81:Me** · 10th April 2008, 12:27

Originally Posted by F5 Dave

I wouldn't trust anyone who says run it on 100:1 as far as I could spit them. Sorry if that comes across rude but that is foul advice.

Here's the skinny: Av Gas is not the best fuel to run in a race tuned 2 stroke. A proper blended race gas like VP is the best, but there are various types to suit applications.

lets knock this route on the head. Not legal for buckets. (& expensive).

So the choices are pump gas or Av. Our pump gas is pretty average. The old Leaded pumpgas was pretty good, better than Av. Octane isn't the only measure of performance, people struggle with that concept.

When we first went to unleaded many years ago it was dangerous in highly tuned bikes & it varied, meaning if you tuned it to the limit then the next batch was a liability. So we went to Av, whilst not perfect was a damn sight better than the options. 98 has probably got a lot better than used to be but haven't bothered comparing it too closely. Av is safe & certainly isn't 'hard on engines'.

I think I had the H at ~ 14 or 15:1 (full stroke, I don't buy the ports argument as the pipe effectively supercharges the cylinder)
For the slipway with short straights 98 will be just fine. For longer tracks I'd run av as that is what the timing is set up for.

Run 40:1 with a decent oil. Spectro Gold is what it used to run with very low wear rates.

[cue the people who think I don't know what I'm talking about having their rant]. . . now.

I fully agree, the only thing I'd run at 100:1 is my yamaha 8hp outboard trolling, but on a dingy at full noise entertaining the kids it always gets a slightly higher mix. For $2 a litre for Av gas is the best value for money I've found and as Dave said at least its fresh and the octane is constant.