Going to try 87 this tank

Here is the timing curve for a stock Vmax.

My 95 does run fine on 87 but does it run better on 93?Any better performance?Does 93 have the same amount of ethanol as 87?Might be a consideration if your bike sits a while between rides.I don't know these answers but it might be a consideration for those that do.just my 2 cents.

Well from what i know, its not a question of running better. Higher octane doesnt not mean that the gas has more power....etc. It is the ability for fuel to resist detonation, because the fuel is slower burning. So, if you put higher octane in a vehicle that doesnt need it, you run the risk of actually losing hp, due to a slower burning fuel having less bang for the buck.

It can actually be described this way. A snickers bar actually has more energy than a stick of dynamite......BUT is WAY slower burning.

So of course all of this is if all things are equal. 87 vs 93 has the same amount of ethanol, same amount of impurities....etc.

The kicker on gas pumps is MAY CONTAIN UP TO 10%. I try to buy ethanol free gas no matter where i go.

I would like to but ethanol free gas but the nearest station to me that sells it is 40 miles away.Thier hours of operation are very finicky.It basically takes most of a tank of gas for a round trip.(pointless)Great for those of us that have that option though.

The kicker on gas pumps is MAY CONTAIN UP TO 10%. I try to buy ethanol free gas no matter where i go.

That's all there is out here in this darn state!
This month starts oxygenated blend too!

The stock Vmax piston sits approx .050" in the bore not including the .032" gasket so you're a long way from having a hot spot from too much Quench (in fact it could use more then it has).

one2dmax said:

The stock Vmax piston sits approx .050" in the bore not including the .032" gasket so you're a long way from having a hot spot from too much Quench (in fact it could use more then it has).

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I think it's the opposite.
From Keith Blacks site.
Either way, I'm still going to run the 87. :biglaugh:

Excessive cylinder pressure will encourage engine-destroying detonation and no piston is immune to its' effects. An important first step is to set the assembled quench (a.k.a. "squish") distance to .040". The quench distance is the compressed thickness of the head gasket plus the deck clearance (the distance your piston is down in the bore). If your piston height (not dome height) is above the block deck, subtract the overage from the gasket thickness to get a true assembled quench distance. The quench area is the flat part of the piston that would contact a similar flat area on the cylinder head if you had .000" assembled quench height. In a running engine, the .040" quench decreases to a close collision between the piston and cylinder head. The shock wave from the close collision drives air at high velocity through the combustion chamber. This movement tends to cool hot spots, averages the chamber temperature, reduces detonation and increases power. Take note, on the exhaust cycle, some cooling of the piston occurs due to the closeness of the water- cooled head.

If you are building an engine with steel rods, tight bearings and pistons, modest RPM and automatic transmission, a .035" quench is the minimum practical to run without engine damage. The closer the piston comes to the cylinder head at operating speed, the more turbulence is generated. Unfortunately, the operating quench height varies in an engine as RPM and temperatures change. If aluminum rods, loose pistons (they rock and hit the head), and over 6000 RPM operation is anticipated, a static clearance of .055" could be required. A running quench height in excess of .060" will forfeit the benefits of the quench head design and can cause severe detonation. The suggested .040" static quench height is recommended as a good usable dimension for stock rod engines up to 6500 RPM. Above 6500 RPM, rod selection becomes important. Since it is the close collision between the piston and the cylinder head that reduces the prospect of detonation, never add a shim or head gasket to lower compression on a quench head engine. If you have 10:1 with a proper quench and then add an extra .040" gasket to give 9.5:1 and .080" quench, you will create more ping at 9.5:1 than you had at 10:1. The suitable way to lower the compression is to use a KB dish piston. KB dish (reverse combustion chamber) pistons are designed for maximum quench area. Having part of the combustion chamber in the piston improves the shape of the chamber and flame travel.

I guess for the 10k redline they run/ran a wider quench area where as I only go to 7/7300 with my car.

Starting to sound like engine masters challenge in here

Killjoy said:

Starting to sound like engine masters challenge in here

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Not me !
I'm just a dopey electrician! :biglaugh:
Those engineers knew/know what they were doing when they built this thing!

Interesting write up I must say ...

It's an interesting subject he's discussing for sure and of course from a guy who's been around awhile. I've only ever heard pinging once on these engines and that was with a 13:1 engine with big cams, ported heads, big intake valves and even premium fuel. I believe that engine had the static cam timing less then ideal. You could only hear the ping on the dyno under heavy load. On the street it never would do that that we could hear (the exhaust on that engine was very loud for sure)

Sean, I hope your not taking offense to our discussion.
That's not my intent.
I make no claims to be an engine builder or guru.
What you just mentioned above is/was why I check my plugs on my car for detonation.
I have a full 3" exhaust and a large SR cam and can't hear anything at WOT. LOL!
I guess the same would hold true if I'm riding in the wrong gear lugging her and with the helmet on wouldn't be able to detect it either.
That would be my only concern.

Now one thing to think about.

I have an ignitech ecu for the 07 Vmax. I tested out a couple of ignition curves for the Vmax (and basically copied several of the dynatech curves because they are "known" good curves). I had a tankful of 87 octane, and was running a stock curve. I then tried dyna curve #2 that is about 3 degrees advanced all over and picked up almost 2 hp. I then tried curve #3 which is about 5 degrees advanced and LOST 4 hp.

That really opened my eyes to how a minute change can have BIG results.

Traumahawk said:

Now one thing to think about.

I have an ignitech ecu for the 07 Vmax. I tested out a couple of ignition curves for the Vmax (and basically copied several of the dynatech curves because they are "known" good curves). I had a tankful of 87 octane, and was running a stock curve. I then tried dyna curve #2 that is about 3 degrees advanced all over and picked up almost 2 hp. I then tried curve #3 which is about 5 degrees advanced and LOST 4 hp.

That really opened my eyes to how a minute change can have BIG results.

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Wow that's a lot of pu for $220!
How does that compare to the Ignitech?

93max said:

Wow that's a lot of pu for $220!
How does that compare to the Ignitech?

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I dont really know. I had gotten the Ignitech for the 07 years ago when a group buy was done.

Now, since then Ive seen the Ignitech on the now defunct UFO site for 400+, but with an add on harness, you can use the ignitech to control the Vboost as well, which I do. So, you can control the vboost to do anything that you want.

So, the older dynas, you had preset curves, the new dyna is similar to the ignitech in that you can set the curve for ANYTHING.

As quickly as the Vmax revs, I am a BIG fan of having a rev limiter on the vmax, which both units have.

Both units (Dyna with an LED, and Ignitech with a setting) will allow you to see if the pickup unit is working, which is very useful when trouble shooting.

Traumahawk said:

I dont really know. I had gotten the Ignitech for the 07 years ago when a group buy was done.

Now, since then Ive seen the Ignitech on the now defunct UFO site for 400+, but with an add on harness, you can use the ignitech to control the Vboost as well, which I do. So, you can control the vboost to do anything that you want.

So, the older dynas, you had preset curves, the new dyna is similar to the ignitech in that you can set the curve for ANYTHING.

As quickly as the Vmax revs, I am a BIG fan of having a rev limiter on the vmax, which both units have.

Both units (Dyna with an LED, and Ignitech with a setting) will allow you to see if the pickup unit is working, which is very useful when trouble shooting.

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Yeah, the rev limiter is key!

93max said:

Sean, I hope your not taking offense to our discussion.
That's not my intent.
I make no claims to be an engine builder or guru.
What you just mentioned above is/was why I check my plugs on my car for detonation.
I have a full 3" exhaust and a large SR cam and can't hear anything at WOT. LOL!
I guess the same would hold true if I'm riding in the wrong gear lugging her and with the helmet on wouldn't be able to detect it either.
That would be my only concern.

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No offense at all! Just commenting that anything he might have to say is for sure worth listening to!

Any engine that's tuned aggressively enough to NEED premium fuel will come with knock sensors, which will tell the ECU to pull some timing out if detonation is picked up. Most commonly found on forced induction engines, but some more modern air-cooled bikes or other high performance motors do as well. OEMs have to make these things foolproof- if 87 would genuinely have a chance of damaging the engine and a resulting warranty claim, they engineered in controls to ensure it can safely use it, albeit with reduced power.

With the aftermath of Harvey, premium fuel was hard to find around here for a few weeks (still is outside the city). My Scout says 91+ only, it is a fairly high compression engine. I also ran the snot out of it on 87 and it never missed a beat. People were going insane and literally running out of gas rather than put 87 in their bike thinking the engine would grenade if they disobeyed the warning sticker.

RaWarrior said:

Any engine that's tuned aggressively enough to NEED premium fuel will come with knock sensors, which will tell the ECU to pull some timing out if detonation is picked up. Most commonly found on forced induction engines, but some more modern air-cooled bikes or other high performance motors do as well. OEMs have to make these things foolproof- if 87 would genuinely have a chance of damaging the engine and a resulting warranty claim, they engineered in controls to ensure it can safely use it, albeit with reduced power.

With the aftermath of Harvey, premium fuel was hard to find around here for a few weeks (still is outside the city). My Scout says 91+ only, it is a fairly high compression engine. I also ran the snot out of it on 87 and it never missed a beat. People were going insane and literally running out of gas rather than put 87 in their bike thinking the engine would grenade if they disobeyed the warning sticker.

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Did you do anything to your scout yet? My wife wants to put slip ons on hers.