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Race fuel truths & myths!!!!

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28K views 67 replies 48 participants last post by  Racinkc  
#1 ·
There are many that think race fuel is some kind of instant HP boost, and with certain engine mods, this may be true.....with others you can make LESS, and have wasted a lot of money for nothing beyond that wonderful smell!!!



For the most part; the lowest octane you can run with out detonation will make the best HP.

There's always exceptions.....oxygenated fuels, etc, etc...



Point being...don't waste your money unless you NEED it for your engines sake!!!



(I'll post more info as soon as I can do so from a real keyboard instead of my phone!!)
 
#11 ·
If you have a way of increasing timing and/or compression for your increased octane then you are going to be increasing hp. No carbon buildup on parts from using leaded fuels will not add hp, but it will keep your hp from decreasing as much over time.
 
#14 ·
in my old yfz450 i ran pump gas premium from shell for one tank rode and ran like complete garbage i got a can of U4 from vp and it woke that motor up

it also had a mad port and polished head ported intake

13.5:1 comp piston and a whole bunch more but it helped it run smoother and not choppy and realli poping and everything
 
#15 ·
Forwarding info on what we've tested



CYL.cc 89/93 Oct.

50-80 ..........15:1

100-125 ........13.8:1

175-200.........13:1

250 ............12:1

350 ............11.8

500 ............11.5:1





95/100 Oct.

50-80 ...... 15.5:1

100-125..... 14.3:1

175-200...... 13.5:1

250...... 12.5:1

350...... 12.2:1

500...... 11.8:1





104/110 Oct.

50-80 ..... 16:1

100-125 ..... 15:1

175-200..... 14:1

250..... 13:1

350..... 12.5:1

500..... 12:1







114/120 Oct.

50-80......... 17:1

100-125......... 15.7:1

175-200......... 14.7:1

250......... 14:1

350....... 13:1

500......... 13:1





Methanol

50-80........ 19:1

100-125...... 18:1

175-200...... 16.5:1

250........ 15.7:1

350........ 15:1

500........ 15:1



Many times you can mix up 50-50% blend of Premium Pump gas with Race gas and cover the detonation problem while increasing HP.

If you run a High Compression, detonation prone engine then you will need to use a higher Octane gas to cover problem, but again only enough higher to cover detonation. If this engine needs 110 Octane gas then use that, don't run 120 Octane and think the HP will go up, it won't, you will pay more and get less.





H.P. gains made by Compression Ratio's over 15.5-16/1 are usually lost to

mechanical and friction drag pressures created by higher compression !



Gene
 
#17 ·
I just started playing with the china knock offs.but as far as vp and klots ect.I run heavy mod drag sleds my 1010 cat with nos needs 114 on nos and 100 with no nos.when dyno with no nos and the 114 I will loose 14 HP over running the 100 octane. but will melt down with any thing less than 114 for 660 runs on nos you can run 112 but can't hit the spray untill your well off the line.I have tryed running 114 on a stock 700 crossfire on the dyno and it makes 139 hp on 87 octane abouy 137hp on 92 and less than 130 on 114octane all 2 strokes .lower octane meens wider flash piont .high octane will olny burn for a short burst but faster .if you dont have the comp or timming you are blowing cash and hp out the pipe.ps the 1010 with nos is over 230hp
 
#65 ·
So wrong. Do you even know what kind of RPM's a Lycoming or Continental run? I do, I fly for a living. In the PA31 I fly, we are limited to 2575 RPM's for 3 minutes, and 2400 continuous. Is that high RPM's? Not exactly. The reason for the high octane is the exact opposite of what you are saying. With the amount of power, and the large bore, cylinder pressures are usually high. Add a turbo charger that produces nearly twice the amount of atmospheric pressure (sometime I see nearly 50" of manifold pressure of take off), with no intercooler (to complex/takes up too much space) and the potential for detonation is HUGE! And the only reason the lead is in there is to help cushion detonation if it does happen.



Here are a few picturs from my FB page.



Image




Image




Image








Edit to add. I found a pic of the center stack/avionics. Look at the tach and MP gauges. This picture was taken on the ground, not running. Notice the MP gauge reads atmospheric pressure.



Image
 
#21 ·
Z50King said:
avgas is designed for long stints of high rpm. wont really help a dirtbike out




Its also a dry fuel made to be used high up in the sky. If you use it often and dont add marvels mystery oil or somthing of that sort, It will burn up you cylinder. Friends banshee had it happen as it was bone stock and he thought avgas would bump it up.



I run 91 mixed with regular stock car race gas mixed 50/50. When i ran full race fuel it would have a weird RPM curve, But mixed it pulls hard through all gears on my mini or XR600R. I know its not needed, But keeps the carbon from build up. If you have parts that are always clean and wont rob HP, Im just keeping it where it was new and havnt had a problem yet.