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mxaniac

Octane for 13.5:1

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I have a 2013 with a ported head and cam from Ron Hamp along with a remap and 13.5:1 piston.  I love the motor, he did an incredible job but I do have pinging problems when the weather is cool or when it's very hot.  I'm running VP110 / 92 octane ethanol free at 50/50.  I would have thought that would be enough octane.  Should I be looking at timing or mapping or just dump more octane in it?

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Alright this is a tough one to answer because the octane rating required varies depending on a lot of other factors than just compression alone. But I’ll try to answer it as simply as I can, 93 or 92 octane in your case, alone is pushing it for 13.5:1 compression, but I’ve seen it done and it does work. I would think at a 50/50 mix with 110, final octane number should be at right around 100 or so which *should be totally fine for all conditions. But a lot of other factors come into play, like air temp, barometric pressure, actual air intake temperature which of course affects air density, spark plug temperature range, exhaust set up, but without just soaking you with knowledge, I’d be looking at the mapping but that’s just my opinion. If it was tuned to run at a certain temperature, any deviation up or down is going to cause some sort of symptoms, so it might be worth while getting a vortex ECU or something similar so you can store multiple maps on the ECU that you can select based on current conditions. The HRC tuning tool is cool too if you feel like taking a laptop to the track and looking like a professional. Of course the simplest test is to drain that tank and dump straight 110 in and see how it performs, if that fixes it. Well you know to just run a higher octane and call it a day.

 

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I'm certainly no expert on this topic, I find it somewhat confusing.  I'm under the understanding that under ideal conditions the stoichiometric ratio is the hottest combustion temperature.  If that's so, then I would think that making an engine run richer to cool off combustion is more of a band aid.  That said, I do know you can run an engine so lean it will ping so why is that?  Timing clearly can have a big effect on pinging as well.  So how do you optimize between timing, octane, and A/F ratio?  I suppose that would take a lot of equipment to run the engine under load and look at the A/F, optimize it and then alter timing to get the most power while adding octane as necessary.  A bit over the top for a fat old man like myself that would get better lap times by trading the 12 oz curls for the elliptical.

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run vp t4 or vpr it'll rip and not ping or remap it for u4.4(rip +) . I always run race gas , the bikes love it . What are you saving by mixing a few bucks. Street blaze is unleaded 100 by vp ,t4 is better.

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4 hours ago, mxaniac said:

I'm certainly no expert on this topic, I find it somewhat confusing.  I'm under the understanding that under ideal conditions the stoichiometric ratio is the hottest combustion temperature.  If that's so, then I would think that making an engine run richer to cool off combustion is more of a band aid.  That said, I do know you can run an engine so lean it will ping so why is that?  Timing clearly can have a big effect on pinging as well.  So how do you optimize between timing, octane, and A/F ratio?  I suppose that would take a lot of equipment to run the engine under load and look at the A/F, optimize it and then alter timing to get the most power while adding octane as necessary.  A bit over the top for a fat old man like myself that would get better lap times by trading the 12 oz curls for the elliptical.

Unless the guy that remapped it had no clue what he was doing, there's no way you should be running at anywhere near Stoich (14.7) at Wide Open Throttle.  He should have tuned it for best power at somewhere around 12.0-12.2. My bet is that the timing curve is too aggressive for the fuel octane you're using. Either up the octane of the fuel or take 2-3 degrees out of the timing. Only way to optimize it is on the dyno with a wide band 02 sensor and an ECU tuning tool. You can optimize spark and A/F to achieve best power - then fatten up the fuel curve and take a couple degrees out to make it safe - and/or handle lower octane fuel. I'd also make sure your cooling system is in good shape, and you don't have an air bubble in the system - running too hot will make it ping. Or just do what someone else said - put super high octane fuel in it - and make sure the ping goes away - then you know that's the problem. Ping will happen on warm, high barometer days. Timing has the biggest influence, A/F less so - richer does make it less likely to knock - or burn a piston.

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This issue is tied to the map. It's got too much timing. The Hamp cam and the 13.5-1 piston in that chamber are fine on 91, unless you weigh 350 pounds and it's 125 degrees outside and you're hot lapping the sand drags, up hill.

who wrote the map? The map carries both timing and fuel.

What are circumstances, other than ambient temps, when it detonates?

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Ron Hamp also did the mapping.  I'm very happy with his work so I want to be clear I'm not trying to blame him for anything.  He's a busy guy and it's been several years so I decided to ask the question here, I never told him I've had issues so he hasn't ever had an opportunity to address them.

We're at about 2100 ft altitude, ambient pressure runs around 13.7-13.9 psia.  Temperatures in the 60s and lower will lead to pinging on the bottom end at around 1/4 throttle.  At perhaps 95+ degrees it pings too, I don't recall exactly where but I think it's above half throttle.  RH humidity is always very low here, below 60% throughout riding season.

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On 10/21/2018 at 5:28 PM, Shawn_Mc said:

I'm extremely familiar with RHC.

Buy a can of VP C12 and run it straight. I'm betting you end up with zero problems. By the way, Ron loves that C12

So if I understand correctly you're suggesting that due to a combination of compression AND timing and to some degree A/F ratio I need a high octane fuel.  It isn't JUST because I'm running 13.5:1 compression, it's a number of factors.  If I wanted to run a lower octane fuel I'd need to de-tune my bike, most likely by changing the timing.  I should also stop riding in 125ºF weather and shed some of my 350 pounds while avoiding the uphill sand drags? 

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4 hours ago, mxaniac said:

So if I understand correctly you're suggesting that due to a combination of compression AND timing and to some degree A/F ratio I need a high octane fuel.  It isn't JUST because I'm running 13.5:1 compression, it's a number of factors.  If I wanted to run a lower octane fuel I'd need to de-tune my bike, most likely by changing the timing.  I should also stop riding in 125ºF weather and shed some of my 350 pounds while avoiding the uphill sand drags? 

Exactly. Or simply drink more beer before you ride. Gotta hydrate, so when it scatters the top ring land and oils down the planet, you wont sweat to death pushing it back. Or, run a can of C12 straight. If it still detonates on C12, I'd look at the plug, see if it's lean and definitely call Ron. Something is amiss.

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Email me a copy of the mapping (screenshots are fine too) and I can bump it against the mapping in my 2013 with the same motor package. No way you could run auto fuel in the motor without issues. T4 is great in this motor.

 

I think my mapping ended up quite a bit richer than Ron's but that was quite some time ago. Bike is faaaaast.

 

 

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4 hours ago, Eddie8v said:

Email me a copy of the mapping (screenshots are fine too) and I can bump it against the mapping in my 2013 with the same motor package. No way you could run auto fuel in the motor without issues. T4 is great in this motor.

 

I think my mapping ended up quite a bit richer than Ron's but that was quite some time ago. Bike is faaaaast.

 

 

What does your plug show?

 

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Just now, Shawn_Mc said:

What does your plug show?

 

Plug has been perfect for years, bike runs perfect for years. I know I tweaked the mapping Ron gave me and I think it was quite a bit richer in many spots.  Been a while, I forget. All I know if when I go to a track where I can open that bike up on a straightaway, people come over and ask me "what's in that thing" because ain't nobody catching me and anyone in front is soon to be behind.  

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Kinda wondering if the ECT sensor is correct on the OPs bike. Or there's something funky going on there. These things stay in cold start mode until 160F. And with no thermostat and big radiators, they could be running colder than they probably should be, or if his sensor is doing something weird like going open or something and freaking the ECU out. I dont know how they wired that thermistor, whether it the resistance rises or falls with temp.

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1 minute ago, Shawn_Mc said:

Kinda wondering if the ECT sensor is correct on the OPs bike. Or there's something funky going on there. These things stay in cold start mode until 160F. And with no thermostat and big radiators, they could be running colder than they probably should be, or if his sensor is doing something weird like going open or something and freaking the ECU out. I dont know how they wired that thermistor, whether it the resistance rises or falls with temp.

I think he's running lean, not rich.

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This time of year all the bikes are crammed in to a little shed and the fair weather fun car fills up any open space in the garage.  I really need to build a shop!  Anyway I appreciate everyone's help but I won't see much of my bike for several months.

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This time of year all the bikes are crammed in to a little shed and the fair weather fun car fills up any open space in the garage.  I really need to build a shop!  Anyway I appreciate everyone's help but I won't see much of my bike for several months.
Pull the ECU and ship it to me. I can compare maps and discuss with you, then burn my own 2013 Hamp mapping in for you.

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