[imslow]

I used some MR8 at the last race. Frontierdon. Awesome. F'in unbelievable. I am now a believer. But I found out on the VP page that MR8 is for 125 and 250 2 smokes. Octane 107, leaded, oxygenated, yellow in color. I was running a 4 stroke 500 single.

The VP web page says this shit can be shipped UPS!!

I guess if it works it works. What isn't on their web page is

1. how long it lasts and
2. it says on the can not to leave in the carb/tank. But for how long?
3. I am going for a dyno test on Friday at MM. We'll see. All I know is I kept up with TK's 650 duc. (but he did say there was a "shimmy" in the steering)

I just need to get my post count up.

 

[jbranson]

Haven't tried that shit yet.
But I hope to do a side by side dyno run using VPC12 and VPU4 before too long.

What is the MR8 awesome compared to? What were you running before?

C12 is also used in two strokes...seems a lot of their fuels cross over.

Race fuel definately behaves better than pump gas when the engines get hot.
JohnnyB

 

[imslow]

i was running pump gas before. the VP filled in a flat spot that I had all summer at about 6,250 rpm. Engine ran about 1000 rpm higher . . . and everytime I went past 6250, it was like a little turbo kicked in. I shit you not. It really felt like there was a little second piston that started pumping. I have some left for the dyno run, but it may be bad by now. i am not sure how long a can of opened oxygenated gas stays oxygenated. Looking into it. (Anyone know?)

 

[catboy]

"...leaded, oxygenated..."

pretty useless information:
lead IS actually the oxygenate...a damn good one too. but the clean air act forced the use of mtbe...solved the emmissions problem but created a bigger groundwater problem.

 

[catboy]

"...leaded, oxygenated..."

pretty useless information:
lead IS actually the oxygenate...a damn good one too. but the clean air act forced the use of mtbe...solved the emmissions problem but created a bigger groundwater problem.

 

[Geeto67]

This is bad information:

quote:
"...leaded, oxygenated..."

pretty useless information:
lead IS actually the oxygenate...a damn good one too. but the clean air act forced the use of mtbe...solved the emmissions problem but created a bigger groundwater problem.

This is a little better:

tetra-ethyl lead was used to boost octane levels and stave off pre-ignition but it does not oxygenate the fuel. Oxygenating is adding an oxygenating substrate to fuel and lead does not do this. Tetra-ethyl lead has no oxygen in it's molecule: (CH3CH2)4Pb . MTBE and Ethanol are compounds that contain oxygen and are added to reduce the amount of unburned gas and carbon monoxide. They do not significanlty increase the octane rating.

In racing fuels Lead is required to get to octane levels above 101 - there are currently no other additives that work as well and are as commercially available as lead.

Lead is also used to prevent erosion in the valve seals and seats.



Edited by - geeto67 on Oct 18 2006 10:38:59 AM

 

[bfd]

We're pretty lucky here to have 110 octane Cam2 at the local gas station. I had been running it mixed with 93 in the Hondas. The C12 felt like it made a difference, higher rpms according to the tach. An actual dyno comparison would be really interesting.

Had been running straight Cam2 in the sidecar but starting mixing it down with 93 on the advice of an old racer. Those heads like some extra heat to help with combustion if not running dual plugs
bfd

 

[catboy]

i stand humbly corrected...

 

[jbranson]

Scott, an opened can of oxygenated fuel will last plenty long if it's kept sealed....meaning the cap is on the can. Most race fuels will go bad rather quickly if left exposed to the open air.
They have additives that vaporize at very low temps and do so quickly in the open air.

I can imagine that the VP would feel very different than pump gas. I've never even tried running my bikes on pump gas.
JohnnyB

 

[Geeto67]

quote:
Scott, an opened can of oxygenated fuel will last plenty long if it's kept sealed....meaning the cap is on the can. Most race fuels will go bad rather quickly if left exposed to the open air.
They have additives that vaporize at very low temps and do so quickly in the open air.

I can imagine that the VP would feel very different than pump gas. I've never even tried running my bikes on pump gas.
JohnnyB

Standard gasoline has about a 60 day shelf life in an open container before varnishes begin to cut its combustibility. In a sealed gas can you have maybe an extra 30 days but that is it. With Stabil you can increase it to two years.

I know plenty of car drag racers who have open containers that keep them for 6 months easily (provided the container has a lid on and there is no air leak). One of the local honda car racers has a 50 gal drum for a year now and he says it is still good (although he seals it after pumping out any he needs).

 

[BANDIT]

One of our VRRA races takes place in North Bay at an airport. We convert it to a track just like the guys that came back from WW2 did. Anyway, while up there I go and get some Av gas (aviation) and the little 350 really wakes up. Anybody tried using Av gas?


BANDIT

By the way, is there anyway to get notifications to replies like on other websites? I've searched this site but either I can't see it or it does not exist, any help appreciated.

 

[jbranson]

I used to run AV gas in a Harley sportster way back. And yes it did run way better. Ran better on Cam2 also.
JohnnyB

 

[Geeto67]

New Laws prohibit people from AVGAS from being sold for automotive applications. If you get busted it isn't just a fine it's a few days in the pokey to boot.

My father is a pilot and I used to work the flightline at Republic airport and Montauk Airport as a kid (no gas at MTP), so the stuff has always been accessible to me. Een now I can still get cans of it. I used to run it in my GTO before I rebuilt the engine because it was one of the few places I could get leaded gas. When I rebuilt the engine I lowered the compression to 9:1 (from stock 10.5:1) and installed hardened valve seats. The car runs like a champ and is as fast as she ever was. In the old days avgas went all the way to 115 octaine, today it is all 100 octaine low lead.

A note about running it in your bike. Unless you have 9.5:1 compression or higher, big cams, etc...Avgas or racing fuel will not help you. It is a common misconception that high octane fuel is a power adder - it is not at all. All it does is allow engines with massive squeeze or high lift /high duration cams to run their optimal by preventing preignition and detonation (pretty much the same thing and can rob power in the same way hitting an upward moving piston with a sledge hammer can rob power). Cam2 lead free 100 octaine is a much better fuel and costs about the same, if I had the choice I would take the cam2.

If you have a bone stock 1970's street bike you should not even think about running premium (92 or 93 octaine), let alone race fuel. Even the vaunted high performance superbikes of the 70's like the cb750 , z1, and gs750 run off of regular. As long as you are tuned up good Reuglar will give you the best performance.

That being said I run premium in my cb750 during the summer months only and here is why: 1) Premium is less likely to contain higher concentrations of ethanol, and 2) I ride in a lot of heavy traffic and a cb750 will begin to detonate when she starts to overheat (sounds like rocks in a coffee can). By running premium the engine can get a little hotter in traffic without detonating. It won't totally prevent it but it buys me a few extra minutes while I figure out my next lane splitting line.

 

[imslow]

yeah . . . what gto said. i am over 10:1 and running a big lumpy mega cycle cam.

 

[kenessex]

As usual I will mostly agree with Geeto on this. The exception being that if you are running a stock motor, you ay bee able to take advantage by adjusting your ignition or cam timing. You may be able to gain some performance by avoiding detonation. Unfortunately, I don't think you would be able to find this hp without a dyno.I think the only other advantage canned gas would give is freedom from contamination and a consistant fuel mix. With a stock or mostly stock motor you might as well run pump gas.

Ken

AHRMA 412
Vintage racing - old guys on old bikes

 

[Geeto67]

quote:
As usual I will mostly agree with Geeto on this. The exception being that if you are running a stock motor, you ay bee able to take advantage by adjusting your ignition or cam timing. You may be able to gain some performance by avoiding detonation. Unfortunately, I don't think you would be able to find this hp without a dyno.I think the only other advantage canned gas would give is freedom from contamination and a consistant fuel mix. With a stock or mostly stock motor you might as well run pump gas.

Ken

AHRMA 412
Vintage racing - old guys on old bikes

and as usual I will follow up agreeing with Ken.

stock bike timing takes in to consideration several factors - perfromance, reliablilty, miles per gallon, etc and then attempts to balance them all with the settings. When I used to run my GTO off Avgas I had two timing settings, one for street driving and one for tearing somebody a new arsehole. On cars you can get a noticible difference retarding or advancing timing but with bikes the numbers you deal with are so small you probably couldn't do it without a dyno, and then your bike will have a really rough idle quality.

considering how shitty gas is just about everywhere I'd stick to stock specs if the bike is stock.

 

[kenessex]

Geeto and I are going to make a career out of agreeing with each other, cause we are too smart and too cool for the rest of you guys.
Like Imslow said if you are using a high comp piston and a lumpy cam you gotta use race gas. It isn't just for the performance either. Detonation will destroy a Wiseco 12:1 piston in a Honda XL500 engine if you roadrace it on pump gas. It will even do it twice if you don't learn from the first broken piston.
So the moral is use race gas when you need it and don't bother if you don't.

Ken

AHRMA 412
Vintage racing - old guys on old bikes

 

[texmawby]

well i run the vp u4 in my stocker racebike with k0 cam. it is 94 octane and oxygenated. maybe it's all in my head, but i think it runs better.

ken, i see that i have been replaced in the superiorminds club by geeto. next i guess you'll be offering him a position to come up and teach too.

sheesh!

texy

"bitches!"

 

[jbranson]

Bear in mind that true race fuel like most varieties of VP have more than just octane working for them. VP has gobs of various chemicals that help keep combustion stable at high rpms and temps even on a stock engine.
The engine in my 175...granted is far from stock, but it's only about 10:1 compression. Noticable difference towards the end of a race between VP and even conventional race fuels like Sunoco.
And oxygenated fuels are a whole nuther deal...you get more oxygen in the engine...you make more power, period. Regardles of the level of engine modification.
JohnnyB

 

[kenessex]

Don't worry Tex, I won't be offering anybody else positions until I hire you. I expect to be moving to Georgia either next year or the year after so I might have a better shot at getting you to move then. Atlanta is the hotbed of riding and racing.
Now I don't really know anything about oxygenated furls, but logic would dictate that they have to help make power in any engine. I also have never tried race gas and pump gas in a stock motor to see if there is a difference, but theoreticallythey should be about the same.
I would sure like to put a mostly stock race bike on a dyno and test it out. I wonder if old style 2 valve combustion chambers benefit from more octanes at real high RPM? I know that with a ported head and big carbs a CB350 will spin to 12000 rpm.
Good points made by Texy and JB. I guess you all are still in the superiorminds club.

Ken



AHRMA 412
Vintage racing - old guys on old bikes