cam info
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Senior User
Joined: Apr 2007
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cam info
Does anybody make aftermarket cams for the 7.3? would a bigger cam do anything like it does on a gasser? just curious because i used to build hi-po V8 gas motors and am familiar with bumping up compression ratios istalling bigger cams etc. But does a diesel act the same way towards those sort of things? wouldnt a full roller diesel motor be nice. anyways, I was just thinking about the good ol' days.
Laughing Gas
Joined: Aug 2003
Posts: 919
Likes: 4
From: Newberg Oregon
I havent seen any aftermarket cams but Delta cams ground mine with a little more lift and duration, cant do much on the diesel but it seems to help.
I want to figure out the rocker ratio then fab up some roller rockers to eliminate our rocker problems.
BTW the cam is a roller in these diesels. Uses the same lifters as the chev diesel
I want to figure out the rocker ratio then fab up some roller rockers to eliminate our rocker problems.
BTW the cam is a roller in these diesels. Uses the same lifters as the chev diesel
Last edited by typefour; Jul 2, 2007 at 09:05 PM.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
Must have been a very little more lift, the valves almost touch the pistons on a stock grind cam.
The piston to head clearance is basically the thickness of the head gasket.
7.3 compression ratio is already 21.5 to 1.
If you get 10 PSI out of the turbo, now you are looking at 36.12 to 1.
And with a gasser you thought 12 to 1 was something hot.
The piston to head clearance is basically the thickness of the head gasket.
7.3 compression ratio is already 21.5 to 1.
If you get 10 PSI out of the turbo, now you are looking at 36.12 to 1.
And with a gasser you thought 12 to 1 was something hot.
Laughing Gas
Joined: Aug 2003
Posts: 919
Likes: 4
From: Newberg Oregon
Its just a bit more lift, forgot to write it down when I measured it. I put in the .010 shorter pistons and the rod bushings are bored 5 thou shorter, it will go to 13 lbs but I need this to live a long time. I am a diesel mechanic on airport gse and been doing this for 30 years and have never owned a IDI, you know how you get paranoid about your own stuff but build them for other people and they run the crap out of it, guess I should run it harder.
I still cant post pic whats up with that?
Have a good day Dave
I still cant post pic whats up with that?
Have a good day Dave
Senior User
Joined: Mar 2007
Posts: 205
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Dave...this is the math formula for figuring the "ruff" effect of boost on compression ratio that I use:
example:
cranking compression= 450 PSI
boost= 10 PSI
(((boost/14.7+1))*cranking compression)= XX
square root of XX= "compression ratio with boost"
the reason this is "ruff" is that it uses "cranking compression".........to be exact, it would need the PSI in the cylinder at running rpm (this would then include pumping losses) And Without the effect of combustion on cylinder pressures..............
when "true effective compression ratios" reach about 25-26 to 1, engine efficiency starts to decline ....
crossbones
example:
cranking compression= 450 PSI
boost= 10 PSI
(((boost/14.7+1))*cranking compression)= XX
square root of XX= "compression ratio with boost"
the reason this is "ruff" is that it uses "cranking compression".........to be exact, it would need the PSI in the cylinder at running rpm (this would then include pumping losses) And Without the effect of combustion on cylinder pressures..............
when "true effective compression ratios" reach about 25-26 to 1, engine efficiency starts to decline ....
crossbones
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
I will agree the efficiency goes down, but the power is still there.
Using your method I am over 30 by a good bit.
Using the calculator my machinist friend has, I am over 57 to 1 when it is all wound up.
All I have to do is look in the side mirror, the black smoke says efficiency is out the window and trailing behind me.
As I have said in other posts, if I run my engine hard I can go below 9 MPG rather easily.
Towing in the 20K gross range usually gives me around 11 or 12 MPG.
Keep it below 2300 RPM and lighter on the throttle, I can see around 15 MPG.
Playing with the Dodges is costing me a small fortune in fuel.
But it sure is fun.
When I get time, I want to get some glow plug readings while I am driving around using a few different driving styles.
You may get a kick out of the readings.
Using your method I am over 30 by a good bit.
Using the calculator my machinist friend has, I am over 57 to 1 when it is all wound up.
All I have to do is look in the side mirror, the black smoke says efficiency is out the window and trailing behind me.
As I have said in other posts, if I run my engine hard I can go below 9 MPG rather easily.
Towing in the 20K gross range usually gives me around 11 or 12 MPG.
Keep it below 2300 RPM and lighter on the throttle, I can see around 15 MPG.
Playing with the Dodges is costing me a small fortune in fuel.
But it sure is fun.
When I get time, I want to get some glow plug readings while I am driving around using a few different driving styles.
You may get a kick out of the readings.
