Was told to run 95 Octane for my triple Webers.

[SS30RR]

Hey Guys,

 

Has anyone else heard that your not meant to run too high an octane rated fuel for carbs on normal compression motors?

 

Was speaking to a carb specialist today and he said he would not touch the car until it was on 95 Octane fuel.

 

I thought it was an interesting comment so hoped on the net and found this to be true from what I can see.

 

I kinda can't wait to kill off this full tank of shell 98 to see the difference.

 

 

 

Cheer,

Will.

 

 

[C.A.R.]

Wut?

[Gordo]

If he is a carb specialist he should no. I wonder what an engine specialist would say to that. I guess if it is stock there might be something in that. But as a racing motor would have more compression the higher octane the better. Interested to see what the other guys say.

[nizm0zed]

I think we should wait till Peter weighs in on this one, coz id wager that he, or Les, will know for sure...

 

however, the octane rating of the fuel is going to matter in relation to the compression ratio of the motor, not in how its delivered.

I could see an issue with the carbs if it is a methanol or ethanol fuel and you haven't set up the internal seals for it, eg, the alcohol fuels will react with aluminum and many types of rubber base parts.

my opinion, it sounds like that 'carbie specialist' is a bit of a knob...

[Scoota G]

That sounds close to the biggest load of Clip Clop Plip Plop that i have ever heard.

[dat2kman]

Wot a load f old bollocks!

You tune it to what you are going to use, ie 95

Then absolutely no point whatsoever in using 98 once in a while, it is wank factor!

Unless you tune it for 98, and stick to it, ie maybe a colder plug, and a touch more timing.

 

Higher octane fuels, ie avgas. For race use, an even colder plug, lots, and a fair bit of timing.

 

Your emulsion tubes if not properly selected, could be one reaon why your carby "expert" has covered his arse on this one.

 

In the East African Safari rallies, and other World ralkues, they detune the cars engines to billy-oh, in ase the fuel quality is crap, and it can be in some countries!

[Ledge]

Ive have always had my engines tuned on

the fuel that i will ALWAYS put in it.

I tend to use BP ultimate and tune the car to that

Make sure you have a good reliable tuner who isn't

going to detonate the crap out of your engine especially

if its boosted.

 

Paul

[peter mc]

yer there is some BS going on , if its low comp run it on any fuel that works , it wont be that far out of tune , the carbs have know idear if the fuel is 91, 95, if the fuel has lots of ethanol yer it will play up on the tune 

[Agno]

It reminds me of some customer surveys we did at an old job of mine, one of the reasons people say they don't want to buy straight LPG cars is that LPG isn't always available outside of the city so they get range anxiety. In reality most people never leave their suburb let alone drive accross the Nullabor, maybe your carb guy is trying to cover all bases with thinking like this?

[SS30RR]

Interesting. Thanks guys. Peter broke it down in layman's term best hahahhaa.

 

My next question then is it possible to have a smooth running + good air/fuel set up on a stock L24/L28 hybrid running 45DCOE with the smallest choke possible?

 

Remembering this is normal compression motor. I think it was reading around 160psi in all cylinders when I checked last.

 

I guess the point to my question is more around "Am I over carbed?"

 

I have to confess SWR set it up for pure track use and here's me trotting around town with in : ). (that might be my problem right there really).

[peter mc]

Tune it with 95 and fit 32 or 34 chokes and have some fun, SW will sort it out  he knows his stuff and is a good bloke ,

some tuners like to do things there way , let him do it and see how it goes

[gav240z]

It reminds me of some customer surveys we did at an old job of mine, one of the reasons people say they don't want to buy straight LPG cars is that LPG isn't always available outside of the city so they get range anxiety. In reality most people never leave their suburb let alone drive accross the Nullabor, maybe your carb guy is trying to cover all bases with thinking like this?

 

Yes exactly and this is why people are so worried about electric cars, but in reality they don't drive that far..... Apparently owners of the Chevy Volt love it because they never have to put fuel in it . It just uses the electric motor all the time.

 

LPG is actually a really good fuel also, much cleaner burn.

[frosty240z]

LPG is good although I'd never have a dual fuel car you have to choose one or the other my new xr6 ute eco lpi is great you get stacks of range this is the 4th dedicated gas ute we have had and we worried a bit about range.

 

But like you say we never go on really long trips and even if you do I can get 600km's easy and it gives you plenty of warning before hand I set the trip all the time whenever I get to 450 I just fill it I have probably 100km left that is around town stop starting driving on a trip you get heaps better mileage.