porting heads worth the money?

[53internationalMiniBigRig]

Hiya everyone,
new guy to diesels, but not performance, anyways, I am thinking about running a 6.5 diesel in my 53 international truck, I want to do a performance diesel, what I want to focus on is improving head flow, then increase boost / fuel, and possibly a cam if I can find the parts to beef up the engine to hold at higher rpms. now has anyone had any luck with porting heads on these motors? the answers I am looking for are actual CFM numbers So I can do some HP / TQ calculations, and how much time they have into their heads and money spent. from there i will learn about what i have to do to supply the added flow with fuel etc, so if anyone wants to chime in on that feel free, I am all ears, I want to learn everything that makes a diesel different than a gas motor. thanks folks

[sctrailrider]

I am almost done porting my set now, I don't have any # for you, but I can say that there is A LOT of extra metal in there !! Gasket matching will always help, intake, head, exhaust manifold, turbo flange.... I will be coating things also when things are done.

Don't know how much it will help but if you spend some time looking at all the ports, some time spent with the right tools can't hurt anything and will only help with the exhaust flow exiting the motor, the charge side I don't think will get much better than a gasket matching and smoothing out the casting as it is pressurized.

[DmaxMaverick]

Diesel engines, turbo or not, are very different than gassers in this regard. Anything you do to facilitate cleaner airflow will be beneficial for power and economy. We aren't trying to homogenize air and fuel in the intake tract. Turbulence or swirl are non factors. Any scavenging advantage with a N/A engine is predetermined by the intake plenum, exhaust manifolds/headers and general exhaust system. On a TD, this is a non issue, as both the intake charge and exhaust are pressurized. For the same reason, custom cam grinds haven't shown any real advantage, either.

I don't know of anyone who has actually quantified the benefits of porting. We don't know how much it will help, but it certainly won't hurt. The same applies to gasket matching. The only negative may be your time and/or money spent on the process, and only your use can determine when the investment will return, if it does.

[Robyn]

I am on board with Maverick on this one.

Matching the intake ports so you dont have any nasty ledges is a good thing.

A basic pollish to get rid of any casting bumps will not hurt either.

Basically, just clean them up.

Same on the exhaust, nothing drastic needed, just a light clean up.

As far as the cam goes, I am of the opinion that its pretty much a waste of $$$ here.

The 6.2 and 6.5 NA engines use the same cam as the TD models from 82-2002 all the same.
The diesel is a Blower Motor and the fancy cams really don't do much, at least not like they do in a gasser.
Also you have ZERO extra room in the area of the Piston to valve clearance.
Long duration, big overlaps and high lift are not going to work here.

The pistons are flat on top and when they reach TDC the clearance between the head and the piston is about .045"

Now, the best bang for the buckos $$$$$ can be had by choosing a good turbo with low drive side back pressure and good flow on the compressor.
Possibly a little better air intake hat might help, but the intake manifold is fine.
Definately DO NOT want an EGR type intake. (1/2 ton stuff) use an F engine turbo intake.


Intake air temperature is a killer on a diesel. Keeping this as close to ambient or a little below is the answer.


Once the temps start to climb, and they will when you get past 15 PSI the efficiency of the engine falls on its butt. At max boost of 15 PSI on a hot day this can reach 200F in the intake.
Volumetric efficiency goes away, really quick.

The 6.5 has a thermal limiting factor, in that the engine can make more heat than the cooling system can reject.
You can read about Peninsular diesels 6.5 engine in boats making 400HP
They have all the water in the river, lake or ??? to keep them really cool.
A pickup radiator will not even come close.

About 300 HP is the service limit with good reliability.

You MIGHT get it to 325 if you aftercool it and have a really good turbo that keeps drive side pressure really low.

A charge cooler and a max boost of about 20 PSI is pretty much it. (Generous here)

The head gaskets are going to start complaining and going south if you go past these parameters very much.

Keep the exhaust gas temps at no more than 1000F at the ports and it will live.

Make sure all your injectors are set to pop at nearly the same pressure.

Even injector "POP Pressures" keeps the cyl to cyl timing really close.

This helps keep torsional vibrations due to odd timing under control (smooth running)

Ballance the rotating assembly.

As far as running the engine at higher RPM I would not go there.

These engines are torque makers, not screamers.

The factory red line is plenty.

A 3-1/2 to 4 inch free flowing exhaust is a must on these things.

Huge amounts of black smoke may look cool, but its wasted $$$$$ and under heavy load makes lots of heat that you dont want.

Little black just as you mash it then the stack should clear and under full load the exhaust should be a light gray if it shows.

Black out the top will show you HUGE exhaust temps when pulling hard.

A large efficient radiator and a separate oil cooler is a must have.

200F max coolant temps.

These engines can make 300HP quite easily without lots of back breaking (and wallet breaking) work.

300 HP and 475 LB torque is a nice spot to shoot for.

The Real plus, they will live at these numbers.

Head off into the ozones trying to find 400 HP and blow off your buddies Power strokes, Cummins and so on and you will find a place you won't like.

The Little town of MELTVILLE. Dont go there.


Hope this helps


Missy

[More Power]

The thermodynamic nature of diesel fuel precludes the notion of a "high RPM diesel engine". The burn rate, flame propagation speed, combustibility, and other factors inherent to diesel fuel all contribute to a fairly narrow engine RPM where it is most efficient - i.e. idle to about 3,000-rpm. Gasoline, on the other hand, can be used in an appropriate engine to deliver efficient power over a much wider engine speed range - i.e. idle to 15,000-rpm+ (i.e. MotoGP bike) or more.

Where having a higher engine speed in a diesel is useful is for a racing application, where the driver can run out the RPM to achieve a higher vehicle speed - like Bonneville, 1/4-mile, etc. Even then, something approaching 5,000-rpm is about the tops before an engine's structural limit is reached (heavy crank, rods and pistons, etc.). At higher engine speeds, centrifugal force can easily exceed the dynamic stress of making power.

Porting and polishing can be highly effective in a high RPM gas engine because of its much higher RPMs and associated intake/exhaust flow, but not so much in a diesel. P&P helps a diesel engine, but the effect is not as dramatic.

Still, port matching is worth the effort, primarily to reduce hot spots in the exhaust manifolds and cylinder heads where a mismatch could deflect the flow of the exhaust. Aside from a small boost in performance, this also reduces the heat rejection load the cooling system must deal with. A sharp edge will grab more heat than a smooth transition between the head/manifold port.

[sctrailrider]

So far I agree 100% with everything said here. When I said I am porting my heads and other stuff, I am doing it for my own personal satisfaction, I could have had them flow tested before & after, but that isn't the reason I am spending time on them. My build is a slow and some what anal one on my part, I have been around the race motor shops all my life and have seen all kinds of things done to gassers, with that said, I do have the time and know how to even out the runners so that things are somewhat better than a stock casting as for flow in & out, stock castings, even the GEP I am working on has lots of extra metal where they could have made it better, ie, gasket matching and bumps here & there.

I am not building a big HP motor, by any standards, just taking the time ( I have a lot of extra ) to do some personal feel good things to my build, will it help.... we will never know for sure, I do know that when I do fire it up and hook it to my horse trailer, I will have a good feeling about the mods I have done and I don't even care to put it on the rollers, altho I might one day, as long as it does what I think it should with what I have done to it will be good for me. I am even going to use a turbo that only one other member( that I know of) has and is using that is working very well , RJ is helping me in that area, The Kennedy pistons are here and i chose them over just cutting the top of stock because it made sense to me. Some of the things I am going to do like Ceramic coating things may or may not help, and I hope it doesn't hurt anything also...LOL.. I do know that the right coating in the right place works, I do this as a hobby so it's almost free...

I don't feel the need for speed or big HP anymore, I drive a 650HP big truck for a living so I know what real power from a diesel feels like, and if that was what I wonted from the start, I would have went that way and not this way, after all I do love my 1991 GMC, and it will be with me for a long time I hope.

I have learned that you must know your limits and be happy with them, this build of mine is costing a big wad of $$$$$$$, but I am one of those that get personal satisfaction from doing things myself, even if some of them are a little off on the non beaten path. ( I love a good un ridden trail on the horses)

If you have the tools to match port your stuff and the extra time, then I say go for it, but if you are looking to send them off and have all that fancy stuff done to them, I think it would be a waste of money. Our IDI motors can only produce so much for the money you put in to them, a 2000$ port & polish and coated set of heads would never give you a return on your money, there are so many other things that would need to come together also at a high cost to even show a small gain for your money.

If you are looking for big HP & tork, find a big truck motor and put it in their, then you would have a base motor that could provide you all the power the frame could handle....

[53internationalMiniBigRig]

well mixed reviews then.. yeah I was going to have them sent out to be ported, don't want or need high rpm, allthough it would be fun to hear what a diesel sounds like at 8000 rpm lol. (universal technical institute used to have a 5.7 diesel drag car that spun to 8000rpm.. scary eh?) I may still go with a gas motor, I am still undecided about that. I would really like to try my hand at a diesel though, hence all the questions and joining this board. but thanks y'all the part about swirl never crossed my mind. thanks for that. gonna mill it over a bit more.

[DmaxMaverick]

The consensus didn't seem mixed to me. Your question was, "Is it worth the money?" Bring your street legal gasser truck to a Diesel drag (which are also street legal) and watch the taillights (cuz that's all you're gonna see). Diesel engines don't turn as fast, because they don't need to. Generally, they turn about 1/2 the RPM's for a similar result, despite using 1/2 the fuel. The limiting factor is RPM's. They'll run out of gears long before they run out of power. Fortunately, there's an App for that.

[sctrailrider]

Dmax, that was a good way to put it :)

[Robyn]

Here is a little tid bit of scary proportions

Back in the hay day of the Detroit two stroke diesels I cut my teeth on the 6V and 8V 71 engines and then the V92 series.

Now these engines have a mechanical injector "rack" system that controls all the injectors via along tube on each head with individual little rods that operate each injector.

All this "Monkey motion" has to be adjusted exactly right in order to work properly.

Now to make matters more complicated, there are two cylinder banks with the same stuff and its all tied into the governor, thats on the front end of the blower.

OK
Now if this entire mess is not set perfectly and it BINDS UP :eek: all hell is gonna break loose when you start the thing.

The governor usually handles thing quite well, but if the injector rack jams, then the RPM can go right through the roof (quickly)

These engines ALL have a spring loaded flapper or Damper that can be tripped from the cab to stop the flow of air and stop the engine in the event of a failure in the fuel controls.

OK
Now you mentioned hearing a really fast running diesel.

One night I was at the local (Portland) Detroit diesel Allison shop and they had an 8V92 on the dyno and were doing a run up.

The two stroke detroits sound like they are running twice as fast due to the firing of each hole every time the piston comes up.

A detroit at 2100 RPM (normal redline) sounds like 4200.

Now
This test run up went bad wrong.
The fellow doing the test had not hooked up the shut down damper.

The engine was started and SHOULD have come to an idle, but did not, it immediately went WIDE LOOSE at full fuel.

The RPM sailed past 2100 in a heart beat and as near as can be told it reached in the neighborhood of about 4000 before large chunks started coming off :eek:

I was right next door in the parts departments night office when this thing went up.

Myself and the parts guy immediately knew what had happened and jumped through the door and out into the parking lot.

The place was a mess after the explosion.

The sound was awesome for sure and if you have never heard a Detroit go ballistic it will send chills up your spine.

One other time the techs down there were testing an 8V92 on the engine dyno and were testing it at what they called "emergency power"

This was supposed to be an idea for emergency vehicles and allowed these engines to run to 2900 RPM

OK these guys had this 8V92 wound up to 2900 with a load on it. OMG :eek:

The noise is defening but it sure does have a cool hummmmm to it at that speed.

Sounds like 5800

As Jim pointed out earlier in this thread, the diesel produces its power at much lower speeds and with gobs of torque.

Just a FWIW

The Detroit two stoke diesels were called "High Speed Diesels" but they actually did not run and faster RPM than say a Cat or a Cummins at 2100 REDLINE

The Detroits had an advantage of being somewhat lighter in weight but with the two stroke design could produce the power output of a much larger engine.

The down side was that these engines had to be wound up to make power.
At low speeds the blowers could not move enough air to scavenge the cylinders well and so lugging was not an option.

At say 1200-1400 RPM they would produce lots of smoke and high Exhaust temps that could fry a piston if done over a long time period.

The Detroits were made in various numbers of cylinders
The V12 was dubbed the BUZZIN DOZEN for obvious reasons

Another moniker that was stuck to these V type Detroits was "Double breasted Yamaha" :D

I have owned several and loved them with a passion.

Well so much for High Speed diesel 101

Class dismissed

OH BTW here is a link to so high winding Detroits at the drags :D
http://www.youtube.com/watch?v=8VvGUrL7FYo

Missy

[phantom309]

I,ve never seen a 92 come apart, i,ve had a 6-71 fire up with a stuck injector, in an early 70,s gmc 9500 it sounds pretty awesome,. and it,s terrifying tripping the air shutoff, cable seized. so i had to do it by hand, i was more worried about the old direct drive airplane sized propellor of a fan exploding,.it was howling almost as good as the motor, and i had hair back then and it was stood straight out towards the firewall,.and i couldn't hardly breathe in that wind either,.
we had my 92 with 140mm plugs in it turning 3200,.it seemed to get quieter up that high! :D i lost clutches all the time tho,. i finally tired of reading the detroit liars book,.and got a 3406A, then the horses were horses and not ponies,.and an allen key was the key!!:cool:

Nick

[Robyn]

My 84 Pete had a 3406A with an 18 speed Ranger behind it.

The 3406A at 400 horsies was a great engine.
Its a tad anemic as compared to my 3406E 500 HP beast, but none the less a good engine.

The Detroit V engines made a great package that could be installed in a whole host of things, from trucks to busses and all manner of dirt moving machines.

The lasted a long time and were a great bang for the buck.

Anyway, I did not mean for this to turn into a lets beat on the detroit thread.
Only a reference to diesels that sound like they are going fast.

To some it up.

The 6.5 is not a screamer, never meant to be one.
The engine can produce 300 HP easily and reliably.
Little grinding and pollishing is needed to get there either.

I would spend the money on good solid 6.5 parts like a dual stat crossover, a Kennedy fan clutch and a good radiator.
Next scare up a good turbo that will produce as low a drive side pressure as possible and deliver plenty of air.

A charge cooler is a plus too.

A gauge set (Pyro and boost) is a must.
Install the pyro right at the LH side manifold outlet in the cross over pipe.
This will give very accurate temps.

Good luck

Missy