As someone relatively new to diesel performance, but not to mechanics, has anyone out there attempted to increase efficiency of operation by porting heads? Are there camshafts designed with longer valve timing? Air flow is air flow, gas or diesel, and turbos overcome flow deficiencies by ramming air through, but if a person was rebuilding anyway wouldn't time spent with a die grinder pay off? Porting and increasing airflow, in and out is what horsepower is all about. The "dreaded Novis" were a force at Indy for years, what was their secret? I love the "tricks" some of you have tried, ram air, propane, ect. My first car, back in 58, was a dodge six, I took the hood off, installed a flex pipe on the carb with a bell from a horn on the end. It gave me five mph more in second. I love that kind of hot rodding, where brain replaces pocketbook. Any input along these lines would be appreciated.

 

Port and polishing has been done, the cam is not usually touched. A turbo would be money well spent, heck just enlarging the exhaust and a flow through muffler is a noticeable improvement.

 

Take the money you would spend on a custom cam and the time you would spend with a die grinder and apply it toward a turbo. More bang for the buck.

For cheap mods that work, bigger exhaust with a see through muffler. Ram air, cut the soup bowl out and increase the size of the intake snorkel Ford used.



This will work on your 85 nicely.

 

Or you can even go a little crazy and do a DUAL ram-air setup like this....






....more pictures can be found in my gallery.

 

Hey guys, if you go back and read my post, I was merely trying to start an intellectual discussion on the merits of further mods done when rebuilding as opposed to tearing down and doing. This website has a link at the page bottom that discusses a 350 Chevy in basically stock form with a blower added vs porting and cam then a blower. More than twice the power with less heat. Hmmmmm... there's a message there somewhere isn't there? Before someone points out the obvious ie it's a gasoline engine, not to mention a "CHEVY", I, too, noticed that, but any engine is basically a pump, so similar mods could reasonably be expected to result in similar gains, thats all. http://www.chevyhiperformance.com/te...nfo/index.html

 

No aftermarket cams for the 6.9 or 7.3 that I am aware of, so you would have to have a custom ground cam to do any change there. Big dollars.

Several people have done porting work, no real gain there either. The only time it would be worth the trouble was if you had to have every last horse possible out of the engine.

Real world economical mods that produce results, ram air and bigger free flowing exhaust.
Real world somewhat expensive mods, mill the pistons down to lower compression, add head studs and a turbo. Then run 94 7.3 turbo injectors and IP. Then crank the boost to 20+ PSI.

That gives a compression ratio of about 53 to 1.

Yes it runs.

 

Holy eff...53:1? Thats insane! Wouldn't that totally kill the motor Dave? Thats like 3 times the compression of a gasser...

 

Try more like 5 times the CR of a gasser - very few gasser run more than about 9.5:1 these days - anything higher than that and you can't buy gasoline with high enough octane to keep them from rattling themselves to death.

That's why the internal parts for diesels are so much heavier and beefier - to handle the stresses. A non-turbo IDI runs 22.5:1 compression stock. Run 14.7 psi turbo boost and you double that to 45:1. Boost it a little more and you get the monster Dave drives at 53:1. Of course he built and beefed his motor up a bit to be able to handle it......

 

[but any engine is basically a pump, so similar mods could reasonably be expected to result in similar gains, thats all. [/QUOTE]


i wouldn't want try and move water with an oil pump.........but, if you must for discussion purposes the older Detroit Deisle engines did use a blower; all of them. Then it seems somebody thought .........and put one on a gas engine; it was a roots type blower typically called a 6-71 since that was the motor it came off of. for further discussion purposes, in order to get more power for some applications Detroit also turbo charged the blower with one or two turbos.
there was a land speed record set with a Freightliner truck powered by a detroit 16v92tt(thats a 16 cyl ,92c.i. per cyl, two blowers; four turbos if memory still serves me

 

Yeah, that truck is a beast. I saw it up close at a logging show a few years ago.

I think porting could help a bit in the top end, but the heads have such big ports already you may actually loose some torque if you made them any bigger. If I ever have my heads off, I will probably at least smooth them out some.

 

Motor is fine, there are a few "wish they were dead" Dodges and Power Strokes around here though.

 

Superchargers have been around a lot longer than Detroit diesels but Detroit used then on diesels first, largely because Detroits are two stroke and intake through ports in the cylinder walls with oil for lube in the crankcase ala a four stroke. Dave is of course right when he says turbos are the cheapest power upgrade, but if the heads are off anyway it is relatively easy with a die grinder and carbide bits to at very least clean up the passageways and match the ports to the manifolds. A proper porting job is better but not without finding what should go and what should stay, as grinding the wrong side of the passage can hurt more than help. Think of it like a river, the silt deposits are on the inside of the curve, the deepest water is on the outside where the water flows fastest. Hydrodynamics and areodynamics are very similar only water is denser so effects at a much lower speed. Following is a good site with much good info, albeit for Cummins, about a quarter way through he makes a good case for porting to reduce heat. Daves findings about cylinder temps might acually improve from porting. If that truck of yours ever slows down, between plowing and hauling and what not, you might consider a little grind time yourself Dave, meanwhile keep the faith and keep up the good work. I go in tomorrow for a new shoulder so won't bee able to get online for a while, Merry Christmas all! http://www.dieselinjection.net/BRUCE/articles.html