?? School Bus IDI's vs F-Series ??

[THECACKLER]

Anybody know what the difference is between our engines and the IH 7.3 NA School Bus engines. I have a line on one and am borrowing a truck to go and check it out tomorrow morning. Supposed to be complete with all accessories, but with a wider frame in the Bus I don't have a lot of faith that the accessories will swap over. Someplace I had heard that the IP is governed lower and the cam is different but I hear a lot of things....

 

[starmilt]

The accessories will all swap. As far as I know the cam is the same. and on at least some of them you have to swap the oil cooler.

 

[RLDSL]

The injection pump will be governed around 2700 rpm. Depending on what bus chassis, it will most likely have a front sump oil pan and pickup instead of a rear sump and pickup, and oil cooler will be different. Fuel filter setup is also most likely different , but that's no big deal.

 

[Goofyexponent]

Is there a torque difference between the industrial and consumer versions?

 

[Diesel JD]

I think the different fuel delivery curve an lower governed RPM changes when and where max torque and HP happen. I used an S-series IH IP a few years ago and it pulled harder at low RPM but absolutely limited out at 71 mph with the C6 and 4.10s.

 

[Agnem]

The passenger side exhaust manifold will be different as well, but if your just doing an engine swap and have the old engine, everything will swap over fine.

 

[65sixbanger]

I know they hold more oil, two more quarts I thought

 

[THECACKLER]

Well it turned out to be a 6.9. It was tagged as a 7.3 but it had 7/16" head bolts. I got the gut to drop the price $100 and hauled it home.

JUSTFORD "The accessories will all swap. As far as I know the cam is the same. and on at least some of them you have to swap the oil cooler."
I think you're right about the cooler. I'll pull it and swap it with the just rebuilt one from my 7.3. Thanks...

RDSL "The injection pump will be governed around 2700 rpm. Depending on what bus chassis, it will most likely have a front sump oil pan and pickup instead of a rear sump and pickup, and oil cooler will be different. Fuel filter setup is also most likely different , but that's no big deal."
You are correct on all accounts. Thanks.

DIESEL JD "I think the different fuel delivery curve an lower governed RPM changes when and where max torque and HP happen. I used an S-series IH IP a few years ago and it pulled harder at low RPM but absolutely limited out at 71 mph with the C6 and 4.10s."
Thanks for the heads-up. I'll swap pumps. Thanks.

AGNEM "The passenger side exhaust manifold will be different as well, but if your just doing an engine swap and have the old engine, everything will swap over fine."
I'll swap both just to be sure. Thanks..

I am concerned about the smaller diameter head bolts. I am planning on installing a Banks W/G turbo on it, and under ideal circumstances I would go the ARP stud route, but those are currently out of reach financially for me. Anybody have any guidelines as to how low to set maximum boost as to keep this engine together and reliable? I am currently moving my home and shop over 1600 miles one way and typically load my 3000# net wt. trailer to about 11,000# gross wt. and hit the road. I am assuming the 6.9 will have to work a bit harder on the hills and that alone will bump the boost up. Should I pull the heads and install 7.3 turbo head gaskets to drop the compression? Or am I just worrying too much? I seem to have fallen out of favor with Gods of Cast Iron lately.

 

[rhkcommander]

Anybody have any guidelines as to how low to set maximum boost as to keep this engine together and reliable? I am currently moving my home and shop over 1600 miles one way and typically load my 3000# net wt. trailer to about 11,000# gross wt. and hit the road. I am assuming the 6.9 will have to work a bit harder on the hills and that alone will bump the boost up. Should I pull the heads and install 7.3 turbo head gaskets to drop the compression? Or am I just worrying too much? I seem to have fallen out of favor with Gods of Cast Iron lately.

<10 psi afaik for stock bolts. any more risks the gasket. ATS was 8 if i remember reading properly

 

[starmilt]

I would personally swap gaskets, that way you know where you are at, I don't know about 7.3 gaskets though and keep it under 10 pounds boost.

 

[THECACKLER]

Also what about the flywheel? Can I use a 7.3 flywheel on the 6.9? I have a crappy 6.9 flywheel I got years ago and its much lighter and thinner than the 7.3's.

 

[MIDNIGHT RIDER]

In my own honest opinion, the 6.9 is superior in all aspects to the 7.3, especially when it comes to heavy towing and long hard work.

Back before the internet came along and "learnt" me better, I was happy pushing my old 6.9 to 12-15 PSI boost regularly and if it had anything other that stock head-bolts/gaskets, someone put them in without my knowledge.

I wouldn't lose a lot of sleep over it; but then, I could be wrong and it cost you lots of dollars.

 

[gatorman21218]

In my own honest opinion, the 6.9 is superior in all aspects to the 7.3, especially when it comes to heavy towing and long hard work.

Back before the internet came along and "learnt" me better, I was happy pushing my old 6.9 to 12-15 PSI boost regularly and if it had anything other that stock head-bolts/gaskets, someone put them in without my knowledge.

I wouldn't lose a lot of sleep over it; but then, I could be wrong and it cost you lots of dollars.

Dont you mean before al gore invented it?

 

[Jake S.]

I reg hit 12 psi and 900-950 egts on a stock '87 motor with about 175,000 miles. I have weighed in at 17,000 lbs. at times. Works great. Owned it for 5 years now. Anything that fits a 7.3 will work on a 6.9. The only major differences are the pistons.

 

[65sixbanger]

The crappy flywheel you have that is thinner, is probably a flexplate for an automatic...