my header tube temps are running over 530 degrees..but the motor itself is running 180 degrees. why am i getting these high temp readings? vacum leak?...heres my mods...355, 64cc vortec heads, lunati springs & retainers, zz-9 cam, crane r/rs, sdpc vortec intake, as&m runners, 24# injectors, 52mm t.b. , crane afpr, everything has been balanced , blueprinted, gasket matched, the only thing that isnt done yet is my chip thats being burned for it. does anybody have any ideas on this? could my chip not being in cause this?...thanks

 

Having some fun with the infra red temperature gun, eh?

Don't freak. Totally normal. Exhaust temps are way WAY higher than engine coolant temps ever gets.

About 1/3 of the heat and energy generated from combustion goes eventually to turning the rear wheels. Another 1/3 goes into the cooling system. And the final third goes..... you guess it..... straight out the exhaust (wasted). Explains a lot about why the exhaust gets so hot.

 

damon, are you saying the header tube temps are normal? at 550-600 degrees? everyone is telling me they should be around 350 degrees. it goes from rich to lean and back and forth, and it idles up and down. ive checked for vacuum leaks and cant find any. im beginning to believe i need my chip burnt to make this thing right. any comments?.....thanks

 

350 degrees sounds like exhaust manifold temp. A very different beast.

Headers usually run near 600°. Coated ones are down around 450° or so. I don't see anything unusual in your readings.

http://www.jet-hot.com/pages/techinfo.html

 

I think that advancing timing will lower(?) combustion chamber temp, as well as running lean(?). If you are worried about them being too high you should wrap them in header wrap to avoid melting the engine knock sensor. I did that once.

 

rb83l69, these temps are at idle, what happens to them when im under throttle? or on the interstate at 2200 rpm?....how high will they go?......thanks

 

don't hold this to me but I think at WOT exhuast gasses can get up to 1000-1200degrees


but you think that is hot
try a rotary
1800degrees at WOT for the exhuast gasses

 

EGT's for engines vary from engine to engine vary and the reading depends how far you are from the exhaust port, too. However, generally about 6" from the port, you want to see around 1200* when the engine is under load. You're reading of 550* at idle seems fine to me.

Higher temp indicates a leaner mixture. A lower temp indicates a richer mixture (on a Gasoline engine). As a matter of fact, snowmobilers use EGT's as a means of analyzing carb jetting. Most folks I know (myself included) try to jet around 1250*. Anything over 1350* for a prolonged time frame (on that application) will cause a burn down.

Also, the temp doesn't rise with throttle position. Yes, at idle, the temp will be lower, due to the very small volume of exhaust gas, and tiny combustion, but once the engine is under load (1/4 throttle or more), the EGT's will remain pretty much constant...if the fuel mixture remains constant. And that is one way to tell. My storm idles w/an EGT around 400*, but just get the sled moving (1/8 throttle) and the EGT's jump to 1200 and stay all the way up to WOT at 8200 RPM. That's good jetting.

 

thanks tom, i appreciate the reply....im just gonna put some miles on it and check my plugs, thats the only true way i know of to tell whats going on with it....thanks