M8 Engine Temp
Member
Joined: Jul 2009
Posts: 4,310
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Two main reasons to intercool:
1. Hot air is less dense and therefore contains less molecules of oxygen per unit volume. This means less air for the motor in a given stroke and therefore less power produced.
2. Hot air also causes a higher cylinder temperature and therefore can aid in pre-detonation of the combustion cycle causing what we call, detonation.
1. Hot air is less dense and therefore contains less molecules of oxygen per unit volume. This means less air for the motor in a given stroke and therefore less power produced.
2. Hot air also causes a higher cylinder temperature and therefore can aid in pre-detonation of the combustion cycle causing what we call, detonation.
I challenge anyone to share a dyno of an HD M8 bike running normal head temps of 250 degrees to deliver the same level of performance as the exact same bike after its heat loaded, running head temps of 340+ and lowered spark advance. Not gonna happen. And that was the point of my remarks on heat and its impact on a liquid cooled M8.
I've had the advantage of observing the temps of Engine, Head and Coolant while operating my liquid cooled M8 in "real time" while feeling the performance of the bike at the same time. There is simply no comparison of the bike's performance at 250 vs 340. That was true when it was factory new as it is now after performance upgrades.
Last edited by Heatwave; May 6, 2017 at 10:20 AM.
Intermediate
Joined: Mar 2015
Posts: 26
Likes: 2
From: San Diego
SGS with Harley Heavy Breather, V&H Hi Output slipons, V&H FP3.....during my autotune sessions I was reading temps up to 337* on the FP3 sensor data about 1 minute after coming to a stop in high 70s weather. Cruising on the freeway in 6th gear and 3k RPM I was reading about 278*. I thought those temps seemed very high at first but it seems others that are taking the readings from the FP3 are having similar findings.
Seasoned HDF Member
Joined: Jan 2008
Posts: 13,672
Likes: 11,459
From: State of Confusion
can't comment on all the techno farble garble..but my bike runs like a completely different bike in this cool Spring air than it did over 4000 ft Rattlesnake Pass at 107 degrees out on the way to Lewiston, Idaho last Summer..felt like it was down about 30% hp and a real dog..almost lost it in a turn from tar snakes as slick as a hockey rink..didn't add any value to this post, other than stating the obvious...heat robs power BIG time..and along with high elevation with an air cooled bike, well...nuff' said...buddy had an identical RK on that trip and his oil temp dipstick peaked at 265 which was surprisingly low under the furnace conditions
Member
Joined: Jul 2009
Posts: 4,310
Likes: 1,079
SGS with Harley Heavy Breather, V&H Hi Output slipons, V&H FP3.....during my autotune sessions I was reading temps up to 337* on the FP3 sensor data about 1 minute after coming to a stop in high 70s weather. Cruising on the freeway in 6th gear and 3k RPM I was reading about 278*. I thought those temps seemed very high at first but it seems others that are taking the readings from the FP3 are having similar findings.
HD EFI Guru
Joined: Jan 2008
Posts: 4,488
Likes: 4,774
I know exactly who you, what you've done in the past and I fully understand why spark advance is taken out of the combustion cycle as temps increase. Perhaps if you weren't so focused on always being "right" (or attacking others) you'd take a moment and reflect on my remarks. I fully understand the purpose of removing spark in the combustion cycle but what you seem unwiiling (or perhaps unable) to understand is the impact from a rider's perspective. Namely that the M8 engine (or any efi engine) will experience reduced power as the spark advance is reduced as a result of significantly increased temps where that timing would have been further advanced under average operating temps.
As an "expert" you know that to be a fact. Its why you'd never tune a bike on a dyno with head temps at 340+. Its also why my twin-turbo car and supercharged boat have intercoolers. In fact you'd either let the bike cool or direct more fans to reduce temps to improve performance while dyno-tuning. Not sure why you feel everything must be a "battle royale" but I'm afraid you're wrong with respect to my remarks on "heat". You're focused on the combustion cycle while my remarks were always focused on the riding experience. And "more heat" equals reduced performance after a certain point.
That point of meaningful power loss on a twin-cooled M8 is nearly the same time the designers withdraw spark advance from the tuning tables as a direct result of heat. You know it, I know it and anyone that understands combustion engines knows it. The heat-adjustment timing tables I shared are from HD developers.
Prove me wrong...do a dyno run with an M8 bike at normal operating temps say 250 degrees and then do a dyno run with temps well over 340. Use your own bike as i assume it has what you consider a perfect tune. I guarantee the dyno will show a measureable reduction in power comparing the 250 degree dyno to the 340 degree dyno run.
As an "expert" you know that to be a fact. Its why you'd never tune a bike on a dyno with head temps at 340+. Its also why my twin-turbo car and supercharged boat have intercoolers. In fact you'd either let the bike cool or direct more fans to reduce temps to improve performance while dyno-tuning. Not sure why you feel everything must be a "battle royale" but I'm afraid you're wrong with respect to my remarks on "heat". You're focused on the combustion cycle while my remarks were always focused on the riding experience. And "more heat" equals reduced performance after a certain point.
That point of meaningful power loss on a twin-cooled M8 is nearly the same time the designers withdraw spark advance from the tuning tables as a direct result of heat. You know it, I know it and anyone that understands combustion engines knows it. The heat-adjustment timing tables I shared are from HD developers.
Prove me wrong...do a dyno run with an M8 bike at normal operating temps say 250 degrees and then do a dyno run with temps well over 340. Use your own bike as i assume it has what you consider a perfect tune. I guarantee the dyno will show a measureable reduction in power comparing the 250 degree dyno to the 340 degree dyno run.
Now as far as more heat reducing power, that comes from many things as you ride. The rest of the powertrain has greater power losses as they get hot too. So that transmission and primary have a big effect on what the rider feels not just what the engine is doing. You have just skipped over so much it's not even funny in your misguided assumptions. It's clear that you here just to argue at this time so it's all yours now.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,921
Likes: 8,026
From: poway
It's actual two main reasons:
1. Hot air is less dense and therefore contains less molecules of oxygen per unit volume. This means less air for the motor in a given stroke and therefore less power produced.
2. Hot air also causes a higher cylinder temperature and therefore can aid in pre-detonation of the combustion cycle causing what we call, detonation.
1. Hot air is less dense and therefore contains less molecules of oxygen per unit volume. This means less air for the motor in a given stroke and therefore less power produced.
2. Hot air also causes a higher cylinder temperature and therefore can aid in pre-detonation of the combustion cycle causing what we call, detonation.
#2 only occurs if the motor is not tuned properly.. Too much cylinder pressure for the running temps.. The hot air is minor compared heat of combustion. Not sure what pre-detonation is but any detonation is an issue as it blows away the boundary layer during the combustion process.
Seasoned HDF Member
Joined: Jan 2006
Posts: 11,474
Likes: 3,000
From: Charleston, SC
I was assuming a tuned motor.
#2 only occurs if the motor is not tuned properly.. Too much cylinder pressure for the running temps.. The hot air is minor compared heat of combustion. Not sure what pre-detonation is but any detonation is an issue as it blows away the boundary layer during the combustion process.
#2 only occurs if the motor is not tuned properly.. Too much cylinder pressure for the running temps.. The hot air is minor compared heat of combustion. Not sure what pre-detonation is but any detonation is an issue as it blows away the boundary layer during the combustion process.
I know this because of all the time I spend screwing with my WRX STI, turbo'd rally cars and all those many years on those forums.
https://www.enginebasics.com/Advance...tercooler.html
But carry on. It's cool. Go with what you know right.
Last edited by lp; May 6, 2017 at 12:59 PM.
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Tourer
Joined: Oct 2015
Posts: 476
Likes: 90
From: Westchester, NY
my friend has a 17 SGS with a stage 2 cam kit and full exhaust headers. He recently installed the fan assisted oil cooler and wanted to test it so he rode around (65* temps) and let it idle for awhile after stopping. On his FP3 we watched the temps climb to 340* F. The fan had still not come on.. Is this normal? I told him to check with HD to make sure they enabled the fan on the ECM. He went there and confirmed it was. not sure what's going on.. is this considered normal? Does it only work when it's 90* outside?
maybe a blown fuse, loose connection, or is there something else that needs to be enabled in the ECM? I think these guys are clueless when it comes to the new M8s. Told him to document the issue with them just in case the engine blows and you find yourself trying to justify a replacement.
maybe a blown fuse, loose connection, or is there something else that needs to be enabled in the ECM? I think these guys are clueless when it comes to the new M8s. Told him to document the issue with them just in case the engine blows and you find yourself trying to justify a replacement.
Last edited by Drodrigueznyc; May 6, 2017 at 03:42 PM.
Seasoned HDF Member
Joined: Jan 2008
Posts: 13,672
Likes: 11,459
From: State of Confusion
my friend has a 17 SGS with a stage 2 cam kit and full exhaust headers. He recently installed the fan assisted oil cooler and wanted to test it so he rode around (65* temps) and let it idle for awhile after stopping. On his FP3 we watched the temps climb to 340* F. The fan had still not come on.. Is this normal? I told him to check with HD to make sure they enabled the fan on the ECM. He went there and confirmed it was. not sure what's going on.. is this considered normal? Does it only work when it's 90* outside?
maybe a blown fuse, loose connection, or is there something else that needs to be enabled in the ECM? I think these guys are clueless when it comes to the new M8s. Told him to document the issue with them just in case the engine blows and you find yourself trying to justify a replacement.
maybe a blown fuse, loose connection, or is there something else that needs to be enabled in the ECM? I think these guys are clueless when it comes to the new M8s. Told him to document the issue with them just in case the engine blows and you find yourself trying to justify a replacement.
"is there something else that needs to be enabled in the ECM?"
the dealer needs to enable it...had mine installed in the Winter and first ride out in 30 degree temps it came on and has every ride since..you won't hear the fan, when it's enabled and bike is at operating temp, get off bike while it's idling and place your hand down behind the cooler and it'll be obviously blowing