I would spend that sort of money if this is something I wanted to daily drive but this is mostly just for the fun of it. I already have a F250 7.3 PS as my daily driver which I've sunk some money into fixing it up right. I'm more trying to figure out the best way to get it running to a point where I don't need to worry about it but not to a point where I'm breaking the bank.
Rebuilding a 7.3 IDI Turbo
- Thread starter CalebHa
- Start date
I would spend that sort of money if this is something I wanted to daily drive but this is mostly just for the fun of it. I already have a F250 7.3 PS as my daily driver which I've sunk some money into fixing it up right. I'm more trying to figure out the best way to get it running to a point where I don't need to worry about it but not to a point where I'm breaking the bank.
IDIBRONCO
IDIBRONCO
I would recommend against reusing them. You've already gone this far, so might as well do it right. If you absolutely had to reuse them, I'd say ok, but it just doesn't seem like a recipe for long life.
I don't know about that. I've seen a lot that weren't cracked. Maybe I just didn't look close enough? Then again, I'm thinking that someone ran with leaking injectors for a long time. Maybe the timing was too advanced for a long time? Gasoline in the fuel tank?
u2slow
bilge rat
I would spend the money on a proper TiDi engine.
To me, it is the "best" diesel Ford put in a 250/350/450 truck.
To me, it is the "best" diesel Ford put in a 250/350/450 truck.
XOLATEM
Full Access Member
This is just a dumba question...but...does that 'fracture' show through to the underside...?
All of the cracks are just on the top and appear to be mostly surface level
I have dropped off my block at the machine shop to get the cylinder sleeved and I will rebuild the motor in a few weeks when I get it back. I found pistons from Mahle that I was planning to buy but I just realized that the Pistons I am able to find are low compression pistons with .010 shaved off product number: 224-3512HA. I am curious on what difference I can expect to see going this route? I know the stock 7.3 IDIs have a compression ratio of 21.5:1 but I would like to know what ratio I would have if I lost 0.010 off the pistons. I understand that the appeal would be if I'm trying to increase the boost to make more power but I plan on just keeping it stock. The Mahle catalog shows the stock pistons to be 224-3511HA but I can't seem to find them anywhere that aren't oversized.
XOLATEM
Full Access Member
I am no expert, but I would like to make you aware of a few things to help you not worry with the .010 shorter pistons...
First of all...you are turboed, not NA...the more space you have in the combustion area when the piston is at TDC gives you a little more room to pack in air/fuel mix.
Keeping your boost level stock will not hurt you...there will probably be more than enough to take advantage of any extra room in the combustion area...
There is a difference between static compression ratio and dynamic cylinder filling pressure.
Static ratio is usually measured while things are at a standstill and it is a yardstick used to measure compression potential....it is assumed that there is no valve overlap or other variables in play that would inhibit achieving the maximum compression possible given the mechanical and dimensional parameters.
What cylinder filling and potential compression ratio you actually get when things are in motion is a different story and varies with RPM, intake air velocity and density, exhaust efficiency, scavenging of the unburnable gases in the cylinder before the exhaust valve shuts, and probably a lot of things that my coffee-starved gray mass can't think of or remember at this moment...but hopefully you get the picture...
Another thing to think about is...when the piston manufacturer designs the pistons they are probably assuming that you are rebuilding the engine and the block deck may have needed truing up and the heads (no matter how much we try to stop them) may have also been shaved.
This brings the valves closer to the pistons and the original clearance was not much to begin with...toss in the variable of which head gaskets you finally use and their compressed thickness and I would suppose that the slightly shorter pistons are doing you a favor...
So, if I were you I would sit back, relax, have a cream soda and dream about the extra power potential and margin of safety you will have with those pistons from a reputable manufacturer...
You asked...and I saw it...so that was just my 2 cents...
additionally...I am a little envious of your situation...I am aching to build engines again...but at the moment I don't have my stuff gathered...
Good luck and have fun...
First of all...you are turboed, not NA...the more space you have in the combustion area when the piston is at TDC gives you a little more room to pack in air/fuel mix.
Keeping your boost level stock will not hurt you...there will probably be more than enough to take advantage of any extra room in the combustion area...
There is a difference between static compression ratio and dynamic cylinder filling pressure.
Static ratio is usually measured while things are at a standstill and it is a yardstick used to measure compression potential....it is assumed that there is no valve overlap or other variables in play that would inhibit achieving the maximum compression possible given the mechanical and dimensional parameters.
What cylinder filling and potential compression ratio you actually get when things are in motion is a different story and varies with RPM, intake air velocity and density, exhaust efficiency, scavenging of the unburnable gases in the cylinder before the exhaust valve shuts, and probably a lot of things that my coffee-starved gray mass can't think of or remember at this moment...but hopefully you get the picture...
Another thing to think about is...when the piston manufacturer designs the pistons they are probably assuming that you are rebuilding the engine and the block deck may have needed truing up and the heads (no matter how much we try to stop them) may have also been shaved.
This brings the valves closer to the pistons and the original clearance was not much to begin with...toss in the variable of which head gaskets you finally use and their compressed thickness and I would suppose that the slightly shorter pistons are doing you a favor...
So, if I were you I would sit back, relax, have a cream soda and dream about the extra power potential and margin of safety you will have with those pistons from a reputable manufacturer...
You asked...and I saw it...so that was just my 2 cents...
additionally...I am a little envious of your situation...I am aching to build engines again...but at the moment I don't have my stuff gathered...
Good luck and have fun...
I appreciate everyone's help answering my questions, I have ordered all the parts for my rebuild and will post an update when I get it back together. I did go ahead and order those lower compression pistons (Thanks for your insight XOLATEM), I suppose it will allow me room in the future to throw a bigger turbo and injectors in it if I ever feel like going that route as well.
I've got another question, are the rod bolts/studs reusable? I generally think of rod bolts as non reusable but these studs don't seem easy to remove without damaging something? I am also curious about the head bolts/main cap bolts, I have been told that they are reusable on the IDIs but I wanted to double check with you guys that that is true.
XOLATEM
Full Access Member
Once again...I am no expert...but....if you seach on this site you will get a few different opinions on the head bolts...on the main cap bolts I plan on using mine again unless they feel funny when I tug on them with a torque wrench...but it would be good for you to search here a bit more before you figure what you want to do...
On the rod bolts...I have not seen the stock ones yet...but...I think that you said that the engine had 300k on it...that is a lot of cycling on rod bolts...
If it were me...I would get some really good rod bolts and have them installed in the rods and have a good machine shop resize the big ends to suit...
There is a good amount of weight slinging around inside that oil pan and I want it to stay together...
You might want to just go ahead and go with head studs....good ones...because you might want to turn it up once you get it together and get as much power out of it as reasonable...
But...that is just my opinion...
You will realize what is best for you...
Good luck on it...
On the rod bolts...I have not seen the stock ones yet...but...I think that you said that the engine had 300k on it...that is a lot of cycling on rod bolts...
If it were me...I would get some really good rod bolts and have them installed in the rods and have a good machine shop resize the big ends to suit...
There is a good amount of weight slinging around inside that oil pan and I want it to stay together...
You might want to just go ahead and go with head studs....good ones...because you might want to turn it up once you get it together and get as much power out of it as reasonable...
But...that is just my opinion...
You will realize what is best for you...
Good luck on it...
Head studs are undoubtedly worth it if you already have it apart
@XOLATEM fyi the rods are factory studded, should have no problem reusing them.
I reused my main bolts, there is a girdle and studs available from R&D fwiw
Ok thanks everyone, I will look more into the head studs. Does anyone know a good budget friendly option? I'm not opposed to head studs but $500 is a little steep and I'm trying to stay married haha.
Also does anyone know what the stock head bolts can realistically handle?
Also does anyone know what the stock head bolts can realistically handle?
IDIBRONCO
IDIBRONCO
The general rule is 20 PSI without studs. With your Factory set up, you'll be in no danger from too much boost. The bottom ends of these engine are very overbuilt. They can hold up to a lot of power just like they are. The biggest weak link is the N/A rods. Your Turbo rods will hold up to more power than 98+% of us will ever see. I wouldn't worry at all about the bottom end.
No there isn't a cheaper head stud option.
No there isn't a cheaper head stud option.
