Lead replacement or unleaded fuel?

SP2MAN · 12-30-2007, 7:17 PM

Hey guys

In SA we get LRP 93 (Lead replacement petrol) and unleaded 93/95 inland. Which one is going to give me more hp?

Thanks

Going to install pciii next month! Can't wait to see what the Stealth slip-ons and DNA air filters with PCiii going to do! Aiming for 130hp+. Already had 122hp stock (done flapper removal and no soft rev limiter).

slickwill · 12-30-2007, 8:27 PM

If the octane rating is the same the power should be similar. If I understand right the lead replacement is just for anti-wear properties, it replaces the lead with safer alternatives that still offer the "cushion" that the lead offers. It shouldn't influence power output very much. The only way to know would be to dyno both of them on the same day, at the same operating temperature, on the same dyno, etc.

lanbrown · 12-30-2007, 8:54 PM

Go with the cheaper of the two.

THE JESTER · 12-30-2007, 9:49 PM

A little known fact about octane ratings is that higher octane fuels do not always produce more power.If you burn equal amounts of super unleaded and normal unleaded they release the same amount of energy.The octane rating of a fuel relates to its tendancy to spontaneously ignite under pressure.A fuel with a higher octane rating will withstand more compression before it ignites. A car/motor cycle with an ecu that controls ignition timing can adapt to different fuels by adjusting the timing advance on higher octane fuels this leads to gain in power output.If you can't adjust your ignition timing you will not get any benifit running high octane fuels other than your engine will not suffer from pre-detonation.

SP2MAN · 12-31-2007, 6:50 AM

Quote:

Originally Posted by slickwill

If the octane rating is the same the power should be similar. If I understand right the lead replacement is just for anti-wear properties, it replaces the lead with safer alternatives that still offer the "cushion" that the lead offers. It shouldn't influence power output very much. The only way to know would be to dyno both of them on the same day, at the same operating temperature, on the same dyno, etc.

Anybody out there that did dyno test with LRP and unleaded? Any difference?

CBR929RE · 12-31-2007, 1:44 PM

doesn't Honda recommend unleaded?

SP2MAN · 12-31-2007, 1:57 PM

Quote:

Originally Posted by CBR929RE

doesn't Honda recommend unleaded?

I hear what you say but doesn't Honda also recommend the soft rev/flapper valve/pair system etc. etc. ? The RC51 isn't equipped with a cat converter so in the good old days of leaded petrol the bikes could run on leaded.

The question is. Can LRP petrol give better engine performance?

CBR929RE · 12-31-2007, 7:13 PM

Quote:

Originally Posted by SP2MAN

I hear what you say but doesn't Honda also recommend the soft rev/flapper valve/pair system etc. etc. ? The RC51 isn't equipped with a cat converter so in the good old days of leaded petrol the bikes could run on leaded.

The question is. Can LRP petrol give better engine performance?

but the lead also has to do with the valve seats. I don't know if running leaded fuel in an engine designed to run on unleaded hurts it or not but I know running unleaded in an engine designed to run leaded will ruin the valve seats.

as far as better performance I have no idea.

slickwill · 12-31-2007, 8:37 PM

The old school engines didn't have hardened valve seats. The lead provided the necessary lube and cushion to make up for it. So for engines that don't have hardened valve seats the lead or lead replacement is required. If I read your first post correct you are getting 93 octane either way so it shouldn't make any difference for power. The extra cushion provided by the lead replacement might help longevity and engine wear but it really shouldn't be needed.

Twincam · 01-01-2008, 9:22 AM

Isnt LRP roughly the same as 4 Star? I have a few classic cars which runs on 4 star with the help of Reddex to keep the exhaust valve sleeves from being worn away. If i was to run unleaded in them, i would have to change the sleeves so that they could hack the different fuel.

Ive never heard of Motorbikes being run on LRP before, only unleaded.

jonathan · 01-04-2008, 7:19 AM

Quote:

Originally Posted by CBR929RE

but the lead also has to do with the valve seats. I don't know if running leaded fuel in an engine designed to run on unleaded hurts it or not but I know running unleaded in an engine designed to run leaded will ruin the valve seats.

as far as better performance I have no idea.

And another issue, the lead or lead replacment will contaminate the engine internal more.
This means the plugs will be less clean hence the spark will be weaker - not good for engine perfomance.

SP2MAN · 01-04-2008, 8:03 AM

Quote:

Originally Posted by jonathan

And another issue, the lead or lead replacment will contaminate the engine internal more.
This means the plugs will be less clean hence the spark will be weaker - not good for engine perfomance.

Thanks! Makes sence. I'll run 93 unleaded. I used to run 95 but as per Roque you get more hp out of lower octane fuel. Where I live its 1,370 m (4,495 ft) above sea level and humidity ranges 30-80%(average 50%). Any thoughts?

jonathan · 01-04-2008, 11:39 AM

Quote:

Originally Posted by SP2MAN

Thanks! Makes sence. I'll run 93 unleaded. I used to run 95 but as per Roque you get more hp out of lower octane fuel. Where I live its 1,370 m (4,495 ft) above sea level and humidity ranges 30-80%(average 50%). Any thoughts?

As to what - the height?
If anything the height above see level will make the engine weaker -
less Oxygen per volume means less fuel can be burned efficiently per cycle.
There is no way round this, however correct mixture must still be hold.

The RC injection system has an atmospheric sensor so most likely
this is within its range.

As for humidety:
this is not a problem, or anything you can correct.
I leave in the same conditions, but you need to consider temperture and humidity as a combination
not just hummidity.

SP2MAN · 01-05-2008, 7:27 AM

Quote:

Originally Posted by jonathan

As to what - the height?
If anything the height above see level will make the engine weaker -
less Oxygen per volume means less fuel can be burned efficiently per cycle.
There is no way round this, however correct mixture must still be hold.

The RC injection system has an atmospheric sensor so most likely
this is within its range.

As for humidety:
this is not a problem, or anything you can correct.
I leave in the same conditions, but you need to consider temperture and humidity as a combination
not just hummidity.

Thanks man. Helps alot!

jonathan · 01-06-2008, 2:57 AM

Quote:

Originally Posted by SP2MAN

Thanks man. Helps alot!

Another issue.

I'm not sure how's things in South Africa, but LR fuels here are not used much,
So the fuel in the fuel station tanks gets older than the regular unleaded.
This means it has degraded more - once more go for the regular most
frequantly furbished fuel supply.