| Author | Message | ||
     Olbolt |
I'm getting ready to have my S3 exhaust pipe Jet-Hot coated, and one of the promises is a reduced pipe temperature. I needed a baseline, with my stock pipe to verify the claim. Yesterday it was mid 30's in Ohio, so I clamped a type K thermocouple to my rear pipe at the first curve and relatively quickly got a stable 775 deg. F. at idle. Later I did the front pipe and got a stable 750 deg. relatively quickly again at idle. I took the Buell on the road, in traffic and the front pipe ranged ~ 380 deg F. no matter what the throttle position or speed were. I didn't have a good set-up to secure the Fluke meter, so this part of the test was short. After hand sanding the pipe to attain a brushed SS finish, I have noticed in the past that my rear pipe quickly discolored approaching a blue tint at the 1st curve vs a straw color on the front pipe at the 1st curve. This 25 deg hotter on the rear is the question... Is this normal, or do I have a FI related issue? Thanks in advance for comments... ps: This is a good running bike, getting ~ 54 mpg average over 12k miles. (it has a very accurate odometer) | ||
| Kalali |
"I took the Buell on the road, in traffic and the front pipe ranged ~ 380 deg F. no matter what the throttle position or speed were..." Sorry but I must be missing something here...380 deg. F vs. 750 deg. F at idle does not make sense to me. Specially in traffic. | ||
| Buellistic |
First of all to start a base line for EXHAUST HEADER temperature the intake manifold "O" rings should be NEW or proven to be good and the same applies to the port/header gaskets ... This is also affected by the timing, CARB. jetting "OR" FUEL INJECTION MAPPING, spark plugs, and the temperature of what time of day you are dong this test ... The same as EXHAUST HEADER WRAPPING the HEADER COATNG(must be coated inside and out) will to a certain extent lower the HEADER TEMPERATURE only because it causes the exhaust gases to move out of the exhaust system quicker, "BUT" the header will still give off enough heat to BURN YOU !!! | ||
| Malott442 |
not only burn, but scar. Ask me how I know?  Plus it will burn pant legs, literally catch them on fire if you wear baggy jeans and they get blown by a breeze to the pipe. Once again , ask me how I know... LOL Jet coating looks great though! | ||
| Pkforbes87 |
I can't speak for jethot coatings, as I've never had one done. As for fiberglass wrapping.. it looks great but does next to nothing for keeping heat inside the header. I even tried high temp silicone paint designed specifically for sealing header wrap and got no noticeable results. | ||
| Skntpig |
I saw a noticeable change in temp when I had mine done. Now mine is only Jet Hot instead of Space Shuttle Hot. I will do it again on any new exhausts I get. | ||
| Olbolt |
Some of my early readings in motion were suspect due to shaky set-up...Here's an update... Today it was 32 deg F (freezing) I started the bike from cold, warmed it up 2 1/2 min where the rocker box was radiating a little heat (my normal routine) and to my surprise, the exhaust read ~ 600 deg. (thermocouple clamped to front pipe at 1st curve w/ ss hose clamp) It pulled good..no stumbling, got to a steady cruise of 35-40 mph for 8 - 10 miles and the temp ranged between 370 - 400 deg F. Then I took it on the freeway for ~ 15 miles @ 65-70 mph with the temp ranging 430 - 480 deg. Two things of interest were observed... 1)Deceleration from 65 to 0 (idle) brought the temp down to 380 deg fast! 2) Idling at a traffic light for 1.5 min got the temp to 575 - 600+ ..it dropped immediately when I got moving. Both events were repeatable. What I'm wondering, is 'has anyone remapped the injection for the rear cylinder to lower the exhaust temp to match the front? or is 25 deg differential reasonable? | ||
| Kilroy |
I would think that, these being air cooled motors, that sitting still would show a rapid increase in temps, followed by a rapid decrease as you get moving, with airflow over the motor. These radiate a ton of heat per design, when air is flowing. Ditto on the front vs rear, more and cooler air is hitting the front cylinder. Just my 0.02 | ||
| Kalali |
It would also be interesting to measure the difference in oil temperature between the circumstances described above, e.g., idle, cruise, etc. What are your guesses? | ||
| Pammy |
Deceleration from 65 to 0 (idle) brought the temp down to 380 deg fast! Engine braking brings oil to the top end very quickly and in mass quantity. Your air fuel ratio goes down quickly and engine timing is higher which results in further cooling. What I'm wondering, is 'has anyone remapped the injection for the rear cylinder to lower the exhaust temp to match the front? We map the cylinders independently(to a certain extent) on bikes that use true dual exhaust. When one pipe scavages for both cylinders it is near impossible. We map for AFR, not temperature(usually). One cylinder being directly behind the other, (blocking the cool wind and supplying more heat), alone, would make tuning for temperature and still have the bike run optimally virtually hopeless, and on an S3 with a common intake runner...not likely, not perfect anyway. You guy amaze me with the tests you do. I love reading about all your experiments. You guys rock! Keep up the good work. It's like Buell mythbusters, very interesting.  | ||
| Oldog |
Kalali: Oil temps tend to move slowly, at least on my gauge they did, =( it takes about 10 miles in cool weather to get the pressure and temperature into warm engine steady state, a normal stop in town will not generate a noticeable change several back to back will show a rise, the harder you run one of these on an interstate, the hotter the oil runs, when moving like that the tend to cool a little quicker than they heat up, Note I placed the sender in the oil return line as I figured that that would be a good average indication of the oils temp vs in the bag. the bike is also equipped with a jagg design oil cooler to. | ||
| Kalali |
Got it. Thanks Oldog. |
