Hey thank you guys i really aprecciate it.


Mike Howard

 

Oil Burner wrote: Mine is a modified F350 running a recently rebuilt 7.3 with rebuilt pump, new injectors and a rebuilt ATS turbo ('92 model) At 1200 miles I put her to the test pulling a 11 1/2 ft Lance and a steel 4 horse trailer over Galena Summit. (6 miles of 6%+ grade) EGT was the big deterent to performance but I kept the rpm's under 2800 the EGT under 950 degrees. I have been wondering about adding a propane boost just for climbing power. I had read that for a given power output propane actually reduces the exhaust gas temperature. Will propane in a 7.3 with a turbo system cause the engine to come unglued from too much power? I opened up the intake to a full 4", installed a K&N filter (highway use only) and am running a 3" through muffler with one bend to get the exhaust out past the wheels. Max boost with the K&N is between 7 and 8 compared to 5 to 6 with the paper filter.
Am I at the limits for the 7.3 and the 5 speed or is there more I can do to get a little more power without blowing the engine or tranny?

 

tdford,
Where is your thermocouple? Pre or Post turbo?

So now it is time to adjust the wastegate and get the boost up to about 10 or 12 or 14 PSI.

 

Dave,
The thermocouple is pre-turbo and is installed in a factory welded insert about 6" below the snail housing. The '92 edition of the ATS turbo on my 91 F350 was the aftermarket version and doesn't feature a waste gate.

I've always thought the boost was on the low side but what else should be tried to increase the turbo performance?

I've thought about an open air scoop but with air conditioning and the oversize stock towing package radiator there isn't enough room to modify the grill frame to position the scoop out the front. The current intake is fashioned from a 4 X 12 inch furnace vent and aluminum ducting and is mounted to the top of the radiator facing forward just above the left battery. Would it be worth building a "pop up" scoop that opened above the hood but could be closed so that the intake was below the hood in rainy or winter snow & slush conditions?

Also, the turbo downpipe is 3" but there doesn't appear to be room for a 4" muffler. Would there be an advantage to transitioning to a 4" pipe just behind the muffler?

 

I took my drivers side radiator support off the radiator and then fabricated a new strap out of 1/4" strap to support it.
Then I ducted the air in from behind the grill through the radiator shell where the old support was located.
It does give me a good ram air effect, I see about 3 PSI boost at 70 MPH coasting down a hill.
It does not increase to total boost, but it does boost faster at lower RPM's.
I never see any adverse results with mine in the rain, but it does have to be disconnected in the snow. Snow packs the air cleaner shut in about 10 miles of driving in heavy snowfall.

Without the wastegate I guess there is not much you can do to increase the boost other than removing the muffler completely.

I have been toying with the idea of making a 4" downpipe and carrying it back to where the stacks split off. I have dual 3" stacks on mine, but the 3" downpipe and 3 feet of 3" pipe to the Y are the most restriction that I have.
I also have a 2003 model ATS turbo with 3" outlet, but it does have the wastegate. A little work will get you over 12 PSI at 3300 RPM.

As far as hood scoops go, I do not hink that would be a very effective way to go. I gave it some carefull consideration when I built my intake behind the grill. The air flow over the top of the hood is not really a good place to get much ram air unless it is real tall or right at the front of the hood. On my 86 if I am driving 75 or 80 MPH in the rain the bottom half of the windshield does not even get rain drops on it. So that tells me the air is not hitting there either, it is being deflected up to the top of the windshield.

Also my thermocouple is in the drivers side exhaust manifold. I will run mine up to 1150 before I start to back out of it. I can also tell you that the pistons look brand new after 17,000 miles of driving and towing at those temps. ( My motor is out and apart on the garage floor right now due to a sleeve dropping in the block and cracking the block issue with the reman engine I installed. The third engine in 28,000 miles so I am looking for a new motor to install from someone that knows how to install sleeves. )

 

Thanks for sharing your knowledge and experience. My first sleeve job lasted 50,000 before the sleeve dropped and with only about 2200 miles on the current rebuild I'm not prepared to give a recomendation but call and talk to the folks at Diesel Auto Services. They convinced me they know how to do a good rebuild with a sleeve job that won't fail.

Your information almost has me convinced to install a second pyro on the driver's side manifold. Might be interesting to compare the two readings since the thermocouple on my 7.3 is only about 6 inches above the crossover T connecting the two manifolds so it's really close to the passenger side manifold but it's being mixed with exhaust from the drivers side that has traveled several feet. Any thoughts on how much temperature loss occurs per inch or foot of pipe past the manifold?

It also sounds like the engine gains pulling capacity by running the engine rpm's up higher than the 2800 number listed as delivering the maximum horse power for the IDI in 1990. Does the turbo boost have the potential to add increased horse power above 2800 rpm as long as the EGT is kept under meltdown?

 

Max boost is not equal to max power. In a diesel, you want torque and most of us here want lots of it.

There are a few things involved in getting the best performance that include, cam timing, IP timing, the IP and how it's built and calibrated, injectors, intake and exhaust and turbo. All these running efficiently together will give you the best performance. You will make max boost at peak torque, which is where you will get the best performace. Stay in the torque curve for how your diesel is setup. Tweaking these components will change the torque curve.

On my 84 SC w/6.9, ATS turbo and exhaust, I had a very good shop rebuild and setup my pump and injectors as a kind of matched set. The pump pressure was increased, flow rate decreased. Put out well over 500 ft. lbs. torque, pulled very good and did not make a lot of heat. When shifting it put out a puff of pretty black smoke and then cleaned right up to nothing but heat showing (a lot like the older Cat motors) It also got right around 24 mpg empty and 18 loaded with camper and boat.

These engines can be setup to really run by the right guy and still be reliable but all the components have got to work together. My old 6.9 would run circles around the 5.9 cummins I currently have, AND got better milage. I've got a bit less than 30,000 on the cummings and have not done any tuning.....yet

 

tdford, I am talking to Diesel Auto Services about my next motor.
Paul and John sound like they know what is going on.

The engine I have now was dyno run before it left the factory.
Peak torque was at 1900 RPM and peak horsepower was at 3100.
Torque was something like 420 foot pounds and horsepower was at 223 right after assembly.
It ran a lot better after about 6000 miles were on the clock and the mileage was increasing with every tankfull even after 16,000 miles.

My max boost was at the redline on the tach.