Exhaust diameter

[crushers]

EGT and water temp are totally related, in that they both come from the same source (containment of the combustion process).

They may react different at different times, however they are related. Run too high EGT's for too long and it will reflect in stressing the coolant system (amoung other things).

For some reading on EGT's, impact and other thoughts go here:

http://www.bankspower.com/Tech_whyegt.cfm

http://www.steves.co.za/Engine_Protection_Units_1.html

hth's

gb

yes, you are right and i sit corrected, both are related as in they both react to teh same source but that is all.
you can run low EGTs (for example 900F) and still boil over on a long hill. you can run low water temps but be over 1200F EGTs.
i have done lots of testing of this with the various pyros i have installed on different engines. the 2 readings are normally unrelated but that being said, a poorer cooling system can lead to higher EGTs over all.
cheers

 

[Greg_B]

my take is simple, no matter what happens to the exhaust side it can not affect the intake side.

Lets beat this horse a little longer.

It's been shown to me you need you get inside the engine to figure the effects of intake and exhaust restrictions. Without getting into the details of 4cyl vs 6cyl, vs v-8...when there is a piston moving up on the compression stroke there is a piston moving down on the ignition stroke. It takes energy to compress the air. Energy removed from output to the wheels. On the intake stroke there is a piston moving up exhaust stroke. Any restriction on one side effects the other side to some extent, impacting total energy left over to turn the rear wheels.

As Brad pointed out, the diesel engine by design is efficient. Once at a certain point, modifications which result in efficiency gains likely are quite small. Add them all together and they could become apparent I would think.

hth's

gb

 

[The Dude]

Lower EGT's can translate into increased efficiency, which is a performance gain of sorts? I think I see what you are saying though, in that you experienced no increase in total output measures (rear wheel HP and Torque). Reducing intake or exhaust restrictions (if present) will allow the engine to become more efficient though...

There are so many variables that would effect all of it. I'll have to see about accessing a dyno for before and after comparisions on a few stock trim JDM's. I am very curious to see the rear wheel results too.

gb

I knew that was going to bite me in the arse...specially from you!!

I agree that you want to maximize your efficiencies. In the case of intake and exhaust on a turbo'd engine, it would be for longevity, through reduction in heat and stress...

If you view those as performance gains, then great. I would view them as preventitive maintaince!! (hehehe) I know we are splitting hairs.

At a recent dyno day, a turbo'd honda removed it's air box (well HKS cold air filter) and found no gains in hp or torque. However the car reached max numbers quicker (his slope on the graph was steeper) by a couple hundred rpm. What does this mean? That the turbo is working more efficiently drawing air into the engine. Not creating more power, but being more efficient. What does this lack of efficiency create...HEAT. but in my experiences, it does not effect power or torque. I would think the same sort of theory could be used for the backend of the engine as well.

On my Duramax, we had the stock exhaust on it on the dyno. Everybody was yapping about the restrictive exhaust, so we got a sawzall and cut it off with no power or torque gains only lower EGTs. It surprised a lot of people.

 

[Greg_B]

IIf you view those as performance gains, then great. I would veiw them as preventitive maintaince!! (hehehe) I know we are splitting hairs.

Cool, thanks. Splitting hairs and confirming understanding of terms would explain this well. Makes sense.

gb

 

[The Dude]

Cool, thanks. Splitting hairs and confirming understanding of terms would explain this well. Makes sense.

gb

not understanding terms is one of the best forms of miscommunication.

I always enjoy discussion with you Greg and reading your posts. I ALWAYS learn something.

 

[Island Moose]

This thread seems to be tailing off...here's some ammunition...

Walla Walla Sweet onion in exhaust pipe reduces EGT's....thoughts?