Engine Operating Temps

[am018]

No from basic thermodynamics  the hotter the water jacket temperature the
higher the mean effective presure (ie torque & power)  because less heat is
rejected to the coolant, in effect the cylinder pressure is higher at towards
the end of the power stroke -- effect of temperature is even more pronunced  on
a turbo engine as this raises the gas temperature at the end of the stroke.
The temperature is of course ristricted by other consideratons --- knock,
engine materials particularly pistons, piston rings and valves   and also the
boiling point of water.

Andy MacFadyen

Mark Romans wrote:


> I disagree about the cooler the more power.  Read Smokey Yunicks
> "Power Secrets" Book.  I originally did the cooler thermostat stuff.  That
> is fine on the dyno,  however on the street in the summer with the ac on I
> have been unable to keep the car that cool. It runs at 220 deg f.  So I
> tuned it to run at that temp.  Pulled some timing out of the map.  Smokey
> says the engine will make 3% more power at 210 deg f. than at a lower temp.
> EFI also allows you to run the max advance and control fuel distribution
> with a nice hot engine.  Before I put the headers on it did 290 hp at the
> rear wheels and it runs a LOT better now.  @ 195 deg f minimum.   Buy the
> book.  Smokey is a very smart guy.
> Mark
> -----Original Message-----
> From: David A. Cooley <n5xmt at bellsouth.net>
> To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
> Date: Monday, October 12, 1998 8:04 PM
> Subject: Re: emulator question
>
> >At 08:10 PM 10/12/98 -0500, you wrote:
> >>
> >>Thanks, I hadn't thought of that (although i haven't even picked
> >>up the motor yet, so i haven't thought about a lot of things yet).
> >>
> >>I intend to install an oil cooler radiator from an RX-7 that's in
> >>my parts bin.  It's the biggest oil cooler i've ever seen, and it
> >>fits perfectly behind my air dam.  don't worry, i'll put a rock
> >>guard and bendable bracket on it.
> >>
> >>I've been told that it's safe to run an engine like this, even with
> >>aluminum heads (this motor has iron heads of course) up to 300 degrees
> >>if i'm using this high-temp coolant.  What do you think of that?
> >
> >Well,
> >It's a proven fact that Gas engines make more power the cooler they are...
> >Allowing the engine to rise to 300 degrees will result in massive amounts
> >of detonation and require the timing to be retarded to the point you make
> >very little power.  That's why performance chips also reccomend you add a
> >cooler thermostat.  Allows them to run more timing/boost (super/turbo
> >charged engines).  Higher temps will also make the oil lose it's viscosity
> >faster and contaminate faster.
> >Later,
> >Dave
> >
> >===========================================================
> >           David Cooley N5XMT           Internet: N5XMT at bellsouth.net
> >     Packet: N5XMT at KQ4LO.#INT.NC.USA.NA   T.A.P.R. Member #7068
> >                     We are Borg... Prepare to be assimilated!
> >===========================================================
> >
>
>