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[lilcoot]

I've increased the compression (10.5:1) in my '12 SESG and had it dyno tuned.

I expected the motor to run as cool or cooler than the canned map that came with the TTS, but it seems to be running 10-20 degrees hotter now.  My limited knowledge of physics makes me think that the higher compression would create higher temps (Charles' or Boyle's Law?), but haven't seen anyone writing about increasing temps after increasing their compression.

I also wonder if the A:F ratio could be a little lean, but my question is:

If all other variables are equal, does increasing compression cause a noticeable/significant rise in operating temps? 

Thanks in advance,

Dan

[Gecko]

Using simple physics: yes. Increased compression equals higher temperature. 

[dlaws01]

As pressure increases, temperature increases.

[ultraswede]

Contray to popular belief, increased static compression make the engine run cooler,
with the same amount of power produced. i.e. cruising say @ 70 mph.

The increase in compression increase the efficiency of the engine,
using less fuel for the same work = less wasted heat and hence cooler running motor.

So to answer the OP, NO not more heat, less heat.

PS of cause provided the engine is tuned with ignition and fuel adjustments for each case. Ds

[prodrag1320]

on paper,yes.but in the real world it can slightly (or greatly) cause more heat.on a higher compression motor the air/fuel charge burns faster,hotter & has a better thermal efficiancy,which makes it more power & better fuel milage,but then detionation may become a problem,so timming is often retarded,and that will build up heat.or CR & cams are not a good match,which will also build heat.so,sadly in alot of cases more heat is the result of going to higher compression.but a well thought out build with all components (cams,compression,combustion chamber/squish & ignition)working together,a  slightly cooler or atleast the same temp motor will result.now that being said,since the air/fuel is being burt at a higher temp in a higher compression motor,the temp of the air being drawn in the combustion chamber has a direct affect also,so a higher compression motor will be affected in hotter weather more so that a lower compression set up

[FLTR2008TRIKE]

on paper,yes.but in the real world it can slightly (or greatly) cause more heat.on a higher compression motor the air/fuel charge burns faster,hotter & has a better thermal efficiancy,which makes it more power & better fuel milage,but then detionation may become a problem,so timming is often retarded,and that will build up heat.or CR & cams are not a good match,which will also build heat.so,sadly in alot of cases more heat is the result of going to higher compression.but a well thought out build with all components (cams,compression,combustion chamber/squish & ignition)working together,a  slightly cooler or atleast the same temp motor will result.now that being said,since the air/fuel is being burt at a higher temp in a higher compression motor,the temp of the air being drawn in the combustion chamber has a direct affect also,so a higher compression motor will be affected in hotter weather more so that a lower compression set up

Kirby,

With what you said. does cam duration on the intake and exhaust have some effect whether or not the engine will have more heat during the cycle of the pistons ?

[prodrag1320]

duration & cam timing will effect cylinder pressures,so yes it will effect temp(as well as the success of the build itself)

[HILLSIDECYCLE.COM]

A 110" CVO with the school-bus cam, at the factory compression of 9.2 can/will run hotter, than say, a 110" CVO, with an S&S .585 set at 10.5.
Scott

[sadunbar]

A 110" CVO with the school-bus cam, at the factory compression of 9.2 can/will run hotter, than say, a 110" CVO, with an S&S .585 set at 10.5.
Scott

That's right...  Because the school-bus SE255 cam produces more cylinder pressure...   

[HD Street Performance]

It can work that way, higher heat.
It is a faster higher energy burn and needs a little help in the cam department to work properly, that being adjusted LSA and exhaust side timing.