Exhaust and engine temps. What do you think?

[scooper77515]

Ater a 5 minute wide open throttle run in 95 degree air temps, I killed the engine and started hitting various spots with my infrared thermometer (measuring surface temperatures).

The jugs were around 140 degrees f. The top of the heads was 120 or less.

What I am most concerned about is the exhaust, since that is what recently burned up on me.

At the junction between the two large exhaust pipes, where the chrome hoseclamp holds them together, and down through the larger diameter of the pipe, it was running around 255-260. Then when it necked down to enter the rubber hose, it was around 245.

Do these sound OK?

Also, how long will the radiator hose I used there last at these temps?

And that clear water line that drains out of the bottom of the jugs and goes out the back, how hot can that get before it melts.

 

[Dr Honda]

Can't say I've ever checked with an IR... but those all sound reasonable.

 

[scooper77515]

I hate when something goes wrong and I fix it and then worry constantly about it happening again.

What about those hoses...will they hold up to those temps?

Especially the clear water line underneath the exhaust pipe.

 

[scooper77515]

By the way, I estimate my temps to melt the hose the first time was in excess of 500 degrees. Maybe WAY in excess.

The green paint I am using on the exhaust pipe is a ceramic engine block paint rated at 500 degrees and it burned right off the rear half of the exhaust pipe.

 

[Dr Honda]

I think the rubber hose can take 250f without too many probs, as long as the water is flowing inside of it. Yes, it's hot... but not burning.

Also, even though you see 250f on the pipe... that's pretty dam cool for an exhaust. I have an EGT on my truck, and I can see it jump to 1200f pretty easy, so you are flowing plenty of water to keep it at that temp.

I'm planning on playing hookey on Friday to play on the water. I'll take an IR with me and take some temps on an engine that is run properly. :cheers:

 

[scooper77515]

I am anxious to hear what your numbers are.

Kinda wierd way to tune a motor, isnt it...

 

[craigy]

That sounds kind of warm to me,although I have been running my water rave down and 3 clicks up.

 

[scooper77515]

I am currently running my regulator (water rave) all the way bottomed out down. I was running it at three turns up but i figured if i lose a little top end and keep it cooler i will do that for now.

I may run it back up a bit as i learn to trust it again.

 

[Dr Honda]

Hi Scooper,

Sorry I didn't this for you earlier, but the weather sucked on Friday, and I couldn't get out until today. I ran pretty hard, but had to let it idle for just a minute or so to get to the shore, and get the seat off.

So here's the numbers.

Head: 135f
spark plugs: 185f
Top of the pipe: 155f
coupler: 180f
Water box: 125f

So... if I didn't have to idle in a 20 yard long, no-wake zone... I'm sure my coupler wold have been as hot as yours. (this was my Si)

I'm planing on taking my boat out next week, and I can pop the deck lid in the water to get an immediate reading if you need it.

 

[scooper77515]

Yeah, I noticed that the temps cool down very quickly when at idle since fresh cool water is running through it. Even cools down quickly after you kill it.

I noticed it would drop 10 degrees in just 20-30 seconds. That is why I was running it wide open and pulling the lanyard, then immediately pulling the hatch and hitting the IR at the various points.

We took the boat out on saturday with 4 adults in it (maxed out the coast guard rating!) and it took longer to plane, but it ran fine. Then dropped everyone off at the beach and hot-dogged with one passenger at a time at long full-throttle runs and it ran just "plane" awesome!

Yet, still in the market for another boat. I may put a For Sale sign on mine the rest of the season... and use the sale price as a down payment on something a bit bigger with more HP. and 4-stroke.

 

[suprajake]

This is something I'm interested in also. Granted I don't have any fancy equipment for measuring, I just put my hand on stuff while boat's idling. I figure as long as I drop it to idle and open the hatch and put my hand on stuff, if I still have skin it's running decent. Probably not the best measurements but hey, I'm cheap and broke! By the way, I'm digging that exhaust paint color! Kind of wishing I had done mine, but again, cheap and broke:cheers:

 

[Dr Honda]

This is something I'm interested in also. Granted I don't have any fancy equipment for measuring, I just put my hand on stuff while boat's idling.

Harbor freight tools has a very cheap IR. I think there basic temp gun is $10 right now, and for $20 you get one with a laser to know where it's pointing at.

 

[scooper77515]

Mine is a name brand but not top of the line. Has laser and i use it to taunt the cat more than measuring temps!!!

Not really. I use it to test for consistent header tube temps on my car (found a loose rocker that way), keep track of bbq and stovetop cook temps, test a/c temps. I was surprised at how often i used it after i got it.

The cat loves it.

 

[suprajake]

Harbor freight tools has a very cheap IR. I think there basic temp gun is $10 right now, and for $20 you get one with a laser to know where it's pointing at.

I might have to check that out! I'd like to know what my engine is doing because I just sunk $500 into a re-sleeve and top-end kit and REALLY don't want to do that again. Not that it was hard, but the price (for me) was up there.

Question though. In the middle of the top piece there's a sensor there. Seems like just a high temp warning light sensor. Is this something that could be replaced by an actual gauge? I mean, could I go to like Auto Zone and buy a gauge and screw it in and go from there? Or do you think that would give me inaccurate readings and/or do damage somehow? If it were up to me I'd have a temp gauge every 6 inches of water travel to watch the temps constantly, but I'm a freak like that!

 

[seadooya]

think Honda's finding, since it was a ski, and not a boat, has way better "ventilation", than Scoops boat does?

 

[scooper77515]

I would love to bypass the buzzer and go with a gauge or two. At least one on the head where ours is, and maybe one at exhaust so i can tell next time I have a burnout.

The ones on my car have a single wire, so I would think it would work. But haven't tried it.