Head studs

[ford69557ci]

I adjusted my wastegate a little today up to 50lbs off the bottle holy #$% that made a huge power difference from 40. Now I am still on stock head bolts and gaskets. who makes a 12mm head stud kit that does not involve any machine work or alot of down time. i wanna turn this up to 60 lbs and then hit the magic buttton but i think on stock studs and gasket it might be a little problem.

[bgilbert]

www.haisleymachine.com.

[rbrettctd]

I think on stock head and studs 50 will be a problem for ya with nos. Im afraid of my 46 and Im #2 only so Im set to 40.

[Begle1]

Retard your timing enough and headgaskets aren't a problem...

[rbrettctd]

How does that work??? Advancing timing drops the boost right?

[BC847]

How does that work??? Advancing timing drops the boost right?

The boost drops as there's more heat converted to work at the crankshaft, leaving less heat in the exhaust gasses to drive the turbine.
With more injection timing advance, the peak cylinder combustion pressures get on up there before TDC, lifting the head if high enough.

[rbrettctd]

So advancing lowers boost but increases pressure, or doesnt reduce boost but rather increases?

[BC847]

Charge-air boost pressure is not to be confused with peak cylinder pressure (or Peak Combustion Pressure).

After the intake valve is closed, the piston has moved up to TDC, pending the fuel injection timing, . . ... is typically where peak cylinder pressure is seen.

It can be influenced by the likes of Charge-Air boost, valves being sunk into the head with common valve-jobs for example, different head-gasket thickness's, piston bowl volume, valve timing, fuel injection timing, etc.

(Assuming the block deck is parallel to the crank, the head surface is parallel to the block, etc, it's common to sink a valve a bit here and there so as to equalize all the complete cylinder's total volume (ref: CC'ing the head). Assuming equal intake volume (intake manifold, intake ports, etc), the ultimate goal is each cylinder being better able to produce it's fullest power potential).



In my earlier post, by injecting the fuel earlier (by advancing the timing), more heat released by the burning fuel is converted to actual work by way of the increased cylinder pressure pushing on the piston.
With that, there's less heat in those gasses shoved out the exhaust valve to spin the turbo.

As such, you've made the engine more efficient in converting fuel to work directly at the crankshaft.


The turbo primarily get it's driving power from those exhaust gasses fed into it, that are still expanding. That point is clearly seen in the typical 300*F or so EGT drop across the turbine (1000*F pre-turbo / 700*F post-turbo for example). That 300*F temperature drop represents the thermal energy being converted to mechanical energy.



Clear as mud?

[rbrettctd]

Just about, Ill reread it when Im a bit more awake nice job though, thanks.

[wingnuts0nr]

In my earlier post, by injecting the fuel earlier (by advancing the timing), more heat released by the burning fuel is converted to actual work by way of the increased cylinder pressure pushing on the piston.
With that, there's less heat in those gasses shoved out the exhaust valve to spin the turbo.

As such, you've made the engine more efficient in converting fuel to work directly at the crankshaft.


The turbo primarily get it's driving power from those exhaust gasses fed into it, that are still expanding. That point is clearly seen in the typical 300*F or so EGT drop across the turbine (1000*F pre-turbo / 700*F post-turbo for example). That 300*F temperature drop represents the thermal energy being converted to mechanical energy.

So My understanding is " if you advance the timing you then make a more efficient and cooler egt running engine"
right

[wannadiesel]

To a certain point. It depends on the amount of fuel you're trying to burn.

[KTA]

And at some point you are just beating the hard parts of the engine up from running too much advance.

[wingnuts0nr]

Yea now clear as mud so it ends up being a trial and error to find the right mix of fuel, air and timing that works best for each application..??

[wannadiesel]

Yep. And you just have to hope the "error" part doesn't cost too much.

[seeker1056]

there is a well known site on the internet that deals with modifyin the larger cummins truck engines and they are adamant that you retard the timing for a motor that you are crankin up the boost and fuel for.

They list like a dozen dyno proven reasons for such as well and show the results

Their end results are 700 and 800 hp engines makin over 2500 ft lbs if memory serves.


A cummins engine is a cummins engine is it not?

Thoughts?