Regular or Premium in the Hawk?
04-29-2009, 09:15 PM
#31
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Thanks surfer. I'm thinking the same way, just don't know if four more degrees of advance would cause trouble on 87. But unless I hear otherwise from several guys who have been running long term on regular with the advance change, I'll go higher octane when I get around to installing the rotor.
04-29-2009, 09:20 PM
#32
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OK, maybe i should have elaborated a bit more. You get absolutely no benefit in running a higher octane gas than what the manufacturer suggest unless you are getting a knock or pinging sound, then step up to the next higher octane.
I was just making the statement that for some they think that adding a higher octane increases hp or performance, only a increase of compression will result in added hp (when speaking of the compression chamber and not the rest of the engine)!
No my bike is not a diesel! My thought process was a high compression ratio is desirable for high octane fuel because it allows an engine to extract more mechanical energy from a given mass of air-fuel mixture due to its higher thermal efficiency. High ratios place the available oxygen and fuel molecules into a reduced space along with the adiabatic heat of compression - causing better mixing and evaporation of the fuel droplets. Thus they allow increased power at the moment of ignition and the extraction of more useful work from that power by expanding the hot gas to a greater degree.
I was just making the statement that for some they think that adding a higher octane increases hp or performance, only a increase of compression will result in added hp (when speaking of the compression chamber and not the rest of the engine)!
No my bike is not a diesel! My thought process was a high compression ratio is desirable for high octane fuel because it allows an engine to extract more mechanical energy from a given mass of air-fuel mixture due to its higher thermal efficiency. High ratios place the available oxygen and fuel molecules into a reduced space along with the adiabatic heat of compression - causing better mixing and evaporation of the fuel droplets. Thus they allow increased power at the moment of ignition and the extraction of more useful work from that power by expanding the hot gas to a greater degree.
Most of my students had never seen a Top Fueler run before and boy, were they impressed.
04-29-2009, 09:29 PM
#33
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I used to show my students videos of NHRA Top Fuelers to explain the power benefits of high compression. They run 12:1 to 13:1 basic compression, but when you add the pressure produced by the Supercharger it goes through the roof=8,000 HP.
Most of my students had never seen a Top Fueler run before and boy, were they impressed.
Most of my students had never seen a Top Fueler run before and boy, were they impressed.
04-30-2009, 05:27 AM
#35
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I think when someone asks a question like this, more information is needed. In this case the country of origin... then only people from THAT country should answer.. my reasoning: I believe in the US we use a different (mathmatical) formula than other countries to derive the octane rating of a particular fuel...
04-30-2009, 03:40 PM
#38
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I ran 92 from sunoco for the common misconception that ooh, it will go faster. It didnt. 89 works for me. Good strong pull out of corners and roll-on acceleration. Just throwin my two cents.
04-30-2009, 03:52 PM
#39
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The US might be different to Australia too. Here we have the choice of 91, 95 (works best in the storm) and 98. The 95 gives a slight improvement over the 91 but running 98 has no extra benefits at all.
04-30-2009, 05:26 PM
#40
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Forget the higher octane gas. Just get some of those E3 Spark Plugs with "Diamond Fire Technology" that I saw bannered at the top of this thread just now.
I'm sure they're good for at least 50 more rear wheel HP.
I'm sure they're good for at least 50 more rear wheel HP.
04-30-2009, 07:35 PM
#42
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I have my own recipe, I mix3 parts of 87 to 1 part of 89, 2 parts of 91.
Then I will add diesel until I hear some detonation, then add 91 until it clears.
I add 2 stroke oil for bouquet.
Then I will add diesel until I hear some detonation, then add 91 until it clears.
I add 2 stroke oil for bouquet.
04-30-2009, 08:50 PM
#43
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05-08-2009, 10:58 AM
#45
KANKS!
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The higher octane ratings are for fuels that resist combustion more. High compression engines need more resistance to prevent detonation or predetonation aka pinging. Putting high octane fuel in a low compression engine like the SH will result in the fuel burning slower and later in the compression stroke. That will reduce power and efficiency thus resulting in poor fuel mileage although the power loss may not be significant enough to notice. Because of the low compression engine in the 'Hawk 87 is recommended. But I'm sure the oil companies don't mind you donating a couple extra dollars every time you fill up.
+100
05-08-2009, 11:14 AM
#46
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I've always used premium and occasionally 110 left over from the dirtbike. Upon reading a little of this thread I tried some regular just to compare.
When I first got the bike it used to die often at stop lights but I cured that. (jetting, tps adjustment, carb sync.) With regular gas it started doing it again which I'm pretty sure is not a coincidence because going back to premium seems to have solved it again so far. I do have the FP +4 advance which I think might have something to do with it.
When I first got the bike it used to die often at stop lights but I cured that. (jetting, tps adjustment, carb sync.) With regular gas it started doing it again which I'm pretty sure is not a coincidence because going back to premium seems to have solved it again so far. I do have the FP +4 advance which I think might have something to do with it.
06-03-2009, 11:51 AM
#47
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High Octane
I have a question: What qualifies for a high compression engine? I thought the Superhawk would fall into that category. I don't know the number off the top of my head, but I would estimate it was between 10:1 and 12:1. I may not be a big city engineer, but when I downshift to first gear, and I'm going any more than 20mph the rear wheel skids. To me that seems like high compression.
06-03-2009, 12:01 PM
#48
I could ride in
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I have a question: What qualifies for a high compression engine? I thought the Superhawk would fall into that category. I don't know the number off the top of my head, but I would estimate it was between 10:1 and 12:1. I may not be a big city engineer, but when I downshift to first gear, and I'm going any more than 20mph the rear wheel skids. To me that seems like high compression.
Kinda low for a modern sporting v-twin motorcycle motor.
Very low for a modern motorcycle motor in general considering the I4's.
Kinda middle to highish for a car.
But it ain't a car.
If it were a racer-replica it'd have a slipper clutch or back torque limiting arrangement and you could back her in the turns like Rossi, LOL!
06-03-2009, 12:05 PM
#49
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High compression is a very relative term. Premium fuel is only needed when an engine`s combination of compression ratio and compression chamber design make it unable to run on regular grade without detonation or pre-ignition. Typically, octane requirement goes up with engine power (measured in specific output as hp/L) as higher compression ratios are typcially called upon to yield higher outputs. THis is not always so, however. A friend of mine had a VW Jetta VR6 which required premium (this despite putting out a very conservative 172 hp from 2.8L, for a specific output of 61.4 hp/L). ON the other hand, the VTR puts out a claimed 109 hp at the crank (for a s.o. of 109 hp/L) and runs on regular. What this tells me is that the VTR combustion chamber design is much more optimal than the VR6`s, enabling it to generate more power while at teh same time requiring lower octane fuel.
I should add that bore size plays a role too (the larger the bore size, the less efficient the piston is at ridding itself of heat, making it more susceptible to detonation).
I should add that bore size plays a role too (the larger the bore size, the less efficient the piston is at ridding itself of heat, making it more susceptible to detonation).
Last edited by mikstr; 06-03-2009 at 12:08 PM.
06-03-2009, 12:25 PM
#51
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I've always used premium and occasionally 110 left over from the dirtbike. Upon reading a little of this thread I tried some regular just to compare.
When I first got the bike it used to die often at stop lights but I cured that. (jetting, tps adjustment, carb sync.) With regular gas it started doing it again which I'm pretty sure is not a coincidence because going back to premium seems to have solved it again so far. I do have the FP +4 advance which I think might have something to do with it.
When I first got the bike it used to die often at stop lights but I cured that. (jetting, tps adjustment, carb sync.) With regular gas it started doing it again which I'm pretty sure is not a coincidence because going back to premium seems to have solved it again so far. I do have the FP +4 advance which I think might have something to do with it.
There's something wrong with your bike, not the gas.
100% of Superhawks rolled of the showroom floor running perfectly on 87 octane. The dealers probably even put some in the tank before the first owner rode off with it.
Last edited by CentralCoaster; 06-03-2009 at 12:27 PM.
06-03-2009, 01:16 PM
#52
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I went on an all day ride last weekend and had switched from 92 to 87 the week prior to see if I noticed any difference. the only thing I noticed was more engine noise. slight ticking at all temps and rpm's. switched back during the ride (had to gas up 4 times over the course of the day, sometimes just to top off tho) and she ran quieter. not making a stand one way or another, but I'll be using 92 from now on.
06-04-2009, 09:38 AM
#55
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I went on an all day ride last weekend and had switched from 92 to 87 the week prior to see if I noticed any difference. the only thing I noticed was more engine noise. slight ticking at all temps and rpm's. switched back during the ride (had to gas up 4 times over the course of the day, sometimes just to top off tho) and she ran quieter. not making a stand one way or another, but I'll be using 92 from now on.
After this post got going I started thinking about it some. I decided to do a little test. As a long-time premium fuel only user I thought I would go to mid grade. At first I only noticed a little difficulty starting (wouldn't kick over on the first push) but that's about it. So the next tank I went with regular. Here are my results:
1) WHAT A MISTAKE.
2) I WILL NEVER DO THAT AGAIN
3) Engine was noisy.
4) Took 2-3 tries to start eveerytime whereas before one, always.
5) The exhaust stunk bad.
6) LESS POWER. 2nd gear wheelie opprotunites were a no-go.
7) No better fuel economy, maybe a touch worse in fact.
I'm sorry beloved VTR, I'll never, I repeat never, do that to you again.
06-04-2009, 09:55 AM
#56
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Very odd.
Despite running decked and ported heads and Yosh Stage 1 cams, I still run 87 octane (as recommended by my dealer, guy who did all the mods) and my bike fires up instantly (and I do mean instantly!) regardless of the outside temp this despite having over 70,000 miles on the odometer). It never runs anything but perfect.
I will only switch to high test once I get my JE pistons in. Until then, 87 is just fine, thank you.
Despite running decked and ported heads and Yosh Stage 1 cams, I still run 87 octane (as recommended by my dealer, guy who did all the mods) and my bike fires up instantly (and I do mean instantly!) regardless of the outside temp this despite having over 70,000 miles on the odometer). It never runs anything but perfect.
I will only switch to high test once I get my JE pistons in. Until then, 87 is just fine, thank you.
06-04-2009, 11:18 AM
#57
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Freekin ethanol
Aside from the Octane question which we have definitively answered What about the ethanol crap we (at least in NY) are forced to use? I'd like to see a dyno chart between 10% ethanol blend and straight up.
I have one station that advertised no ethanol. I KNOW my hawk runs better on that gas regardless of the octane (don't hate me, I use 87).
I have a 40 mile (each way) commute, no traffic, few lights or stops, 95% 45 & 55mph secondary roads, average speed between fill ups 47mph. Little variation and very repeatable MPG results week in and week out. In my TSX (a tarted up accord) I get 33mpg +/-1mpg in the summer on 10% ethanol for this commute. When I fill up with REAL gas that MPG goes to 36 +/- 1. That is a solid 9% increase. The TSX has an integrated computer so I can see the additional mileage as i am getting it. And no, I do not rely on what it tells me, I do the math when I fill up.
Moral? alcohol and gas don't mix. If you can, keep it out of your SHawk.
What about the ethanol crap we (at least in NY) are forced to use? I'd like to see a dyno chart between 10% ethanol blend and straight up.I have one station that advertised no ethanol. I KNOW my hawk runs better on that gas regardless of the octane (don't hate me, I use 87).
I have a 40 mile (each way) commute, no traffic, few lights or stops, 95% 45 & 55mph secondary roads, average speed between fill ups 47mph. Little variation and very repeatable MPG results week in and week out. In my TSX (a tarted up accord) I get 33mpg +/-1mpg in the summer on 10% ethanol for this commute. When I fill up with REAL gas that MPG goes to 36 +/- 1. That is a solid 9% increase. The TSX has an integrated computer so I can see the additional mileage as i am getting it. And no, I do not rely on what it tells me, I do the math when I fill up.
Moral? alcohol and gas don't mix. If you can, keep it out of your SHawk.
06-04-2009, 11:31 AM
#58
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Having worked for one of the first companies to integrate ethanol into their fuel in Canada (over ten years ago), I recall that mileage is supposed to go down about 2% (assuming you are running less than 10% ethanol) due to the latter`s lower energy content. The main isue I have with teh stuff when it comes to the VTR is that the ethanol attacks the diaphragm in the petcock, causing it to tear prematurely (a situation that can leave you stranded on the side of the road... been there, done that... twice!!!). I now avoid the stuff whenever I can.
BTW, due to the oxygenation effect of the ethanol, they recommend going up one jet size on carbureted snowmobiles (so the same should hold true for bikes).
BTW, due to the oxygenation effect of the ethanol, they recommend going up one jet size on carbureted snowmobiles (so the same should hold true for bikes).
06-04-2009, 11:57 AM
#59
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I've read the 2% studies too (sponsored by ADM, Corn Dollars!). I won't dispute it - people who should know write this stuff.
BUT, I know how my car and bike react.
In any case, your point on the oxygenation and jet size makes sense. I know I am running fairly lean, so using the real gas is probably bringing the fuel mix closer to where it should be.
I really think ethanol in the gas has more of an affect on how our bikes run than the octane. For a while around me there were stations that had ethanol in the regular but not in the super. I also suspect the actual ethanol mix may change from station to station and day to day.
My 2 cents - I'll get off my ethanol horse now
BUT, I know how my car and bike react.
In any case, your point on the oxygenation and jet size makes sense. I know I am running fairly lean, so using the real gas is probably bringing the fuel mix closer to where it should be.
I really think ethanol in the gas has more of an affect on how our bikes run than the octane. For a while around me there were stations that had ethanol in the regular but not in the super. I also suspect the actual ethanol mix may change from station to station and day to day.
My 2 cents - I'll get off my ethanol horse now
06-04-2009, 12:03 PM
#60
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Yeah, the mpg loss with E10 is often exaggerated.
Even if ethanol contains ~20% less energy, but there's only 10% of it in the gas... then you actually have only lost 0.20 x 0.10 = 0.02 (2% overall)
Even if ethanol contains ~20% less energy, but there's only 10% of it in the gas... then you actually have only lost 0.20 x 0.10 = 0.02 (2% overall)
