Buddy gave me a truck for christmas, i want to make it my new daily driver.
91 7.3L ZF5 4x4 Reg Cab.
400K mi.
New tranny-t-case-axles, as of 97
Truck parked in 99, he got a new psd.


Goals for my new motor, i am building this for fun, and it needs it, 400K mi.

1. 225-285HP
2. 450-500lb. tq
3. Daily Drivabilty

What do i do here, i have an ATS wastegated system. Let me know everything i can do here to achieve these goals, i think they are easy.

I was also curious if they make a little lower comp pistons for these motors?

Mike

 

I'm working on similar project, but I'm using a 6.9 and going for 350HP.
You should be able to get that with a stock engine, a little extra boost, and the fuel injection pump turned up.

I think for pistions you'll need to take your stock pistons to a competent machine shop and have the top machined off. I did some rough calculations on how much the Comp Ratio changes: .030 removed would put the comp down around 18:1, which would make these engines very hard to start. So a little goes a long way.
There is an outfit that sells high HP parts for these diesels, It's dps-performance.com Its worth going to the web site to get some insight.

 

Why would it be hard to start at 18:1 compression? A stock Powerstroke piston is 17.5:1, and they start easily. You could also stuff 25 pounds of boost in it and not have to worry about the headgaskets every time you put your foot down. If it came down to it, it should not be that hard to scrap the GP system and install an ether assist.

I've had experience, and done business with DPS. Definitey would be worth your while to talk to Ken if interested in building a hi-po 6.9/7.3

 

I based most of my opinion on a sound bit on the DPS site under galleries titled, "Lowered compression 6.9 starting, 50 deg outside" I don't know how low of compression this engine had but it sounded like my wore out 6.9 when its -10 F and forget to push the glow button in. The rest was speculation that the powerstroke during starting changes the fuel timing. I don't know for sure. I'm sure others here, or maybe yourself can prove or disprove this.
I'm planning on an ether assist system for my project engine.
As far as those calculations, I don't recommend using those without checking it out yourself. I plan on purchaseing a burret kit to measure my combustion chamber before any material is removed from my pistons.

 

Since the Power Stroke engine is fly by wire the computer can change any operating parameter that it needs to for it to start. Cycle glow plugs a couple of times, inject more fuel, change the timing and more. Our mechanical IP's can not do this.

I spoke with Ken about parts for mine, he was going to recommend a minimum amount shaved off the pistons so I did not have cold weather starting issues (.010 if I remember right). Just enough to make it easier on the head gaskets.

 

Does anyone make a thicker head gasket? That would accomplish the same result as grinding the top of the pistons and should be a whole lot cheaper.

 

The computer does control the on time of the glow plugs, between 5 and 120 seconds, but it rely's on high pressure oil to push the fuel through the injectors so it cannot simply select more fuel to get it started. And while the electronics are adaptive on a very limited scale, it does not and can not, simpy alter any of it's operating parameters. PSD's are just as hard to start as any other diesel when it has fuel, oil, or glow plug problems.

The PSD does undoubtedly injector more fuel at start up than the IDI, and that may very well be the reasn the IDI's need that high compression ratio...I don't know. If that is the case one could stil make huge power with a lower compression IDI, but it absolutely would make ether assist neccessary.

 

i think the compression ratio is the killer of the good start, high compression equals less timing needed in order to burn the fuel efficiently, i say if you get some low compression pistons and bump the timing up to about 16-20 like i have on my cummins engine, then you could take the glowplugs out of it to make room for a little less compression!! fire right up.

 

Well guys I havent been here in a while so I'll fill in what I can. Everything about our IDI engines is based on the high compression. With Ken his 6.9 is 17:1 compression with I believe quite a bit of porting to the heads and polishing virtually eliminating the precombustion chamber in the head. As most of you all know that is the area the glow plugs warm up. With all this extra space the glow plugs cant warm it up enough for the engine to fire the way it was designed to. I have found some info on this company which may help us.
http://www.espar.com/htm/applies/pickup.htm
I'm also talking to a local shop to see if we can rig up a grid heater as well. I'm preparing to build a 500+hp IDI for pulling. I will be dealing alot with Ken at DPS as well. I'm having the engine balanced to 5000RPM's, Custom cam, Custom head work, intercooling it, custom fuel pump, injectors, fuel system, and maybe even twins. I just got this truck and have been wanting to build one for sometime now and I have my chance. My truck is a 1991, F-250 which will recieve a Dana 60 out front. It has a 5 speed and is a regular cab. As I go along with my slow process I will try and keep you all posted.

Andy

 

IDI engines use the precombustion chamber area, where direct injection engines klike the powerstroke and Cummins do not, and do not require as much compression. EVERY pecombustion chamber type diesel engine has higher compression than ANY direct injection engine. To lower the compression to the level of a direct injection engine would mean harder starts and less power. The turbo would have to raise the compression pressures to make up for it, sacrificing the non-turbo assisted start. Most IDI engines are in the area of 24:1 area new, if I recall correctly. Adding more fuel or any timing adjustments won't make up enough difference to compensate.

 

Well for one the 7.3 IDI is a 21:1 compression ratio. Lowering the compression to 17:1 allows you to be able to stud the heads and fire ring them so you can push in larger amounts of fuel into it. The basic diesel idea is more fuel and air you can push into the combustion chamber the more hp. Yes this will make it a bear to start if the engine is below 60*s. When you recalibrate the pump, extrude hone the injectors and put on a large charger you will definatly gain more hp then you ever could in stock trim. I'm talking about pushing 60+ pounds of boost into my engine when it is done. That would blow the heads right off a stock engine!

Andy

 

how much do you think i will have in this motor when im done,

-.010 on the pistons
harmonically balanced
DPS Pump and Injectors
Head Stud Kit
Nice set of gauges and a pod.
Complete rebuild of all rotating assembly and heads.

granted it will be about 2k less then someone with nothing because i have the ATS wastegated turbo, its about 2 months old and probably doesnt need a rebuild.

Anything else you guys recommend on this one?

Michael Howard

 

Well any good machine shop can mill the pistons for you for a couple hundred dollars. While I was at it I would also ceramic coat the tops and silicone the skirts to help repel the heat, usually about $60 per piston. Every shop is different on balancing so I couldnt really give you an estimate thier. A while ago Ken said that his performance pump was $525 exchanged, injectors style stage one are $36ea exchanged or $64 using new injector. The head stud kit runs $675 for the H-13 7.3 IDI kit and $330 for the 6.9 kit. Ispro boost guage is going to be around $45, pyro will be around $120, and pod is like $30. Figure a hundred or two for new bearings, gaskets, and freeze plugs. When doing the head I would also have valves ceramic coated and lightly polished. Probably have little over $1000 in heads. I would also install a intercooler from Ats if your truck is newer then 92. Oh and you will also need a new fuel sytem to supply it with, FASS should do the trick $550+.

Hope this helps.
Andy

 

Cookie you have to remember that change is relative.
The things you listed that the Power Stroke ECM changes is a lot compare to what the IDI does.

5 to 120 seconds compared to 10 seconds for glow plugs is a huge difference all alone.

I really have no idea about how much the Power Stroke can or does change the timing, but the way it is controlled would leave it open to much more adjustment than bolts can do.

 

hey (my first post) anyhow i have a 1992 7.3 4x4 extended cab extended bed. i would like to know if i can put heads from a turbo 7.3 94-96 non power stroke onto an idi 92 7.3? i have a complete motor a friend blew up. i want to change heads and turbo my my 7.3. thanx. great sight!
jesse