Cummins Mechanical 8.3 Vs Electronic ISC 8.3

[Bon Voyage]

I've got a choice between a couple buses and would like some advice on which to get, the 1997 that will probably have the mechanical 8.3 or the 2000 ISC 8.3 engine. They're full size Thomas buses and Allison transmissions though I don't yet know which tranny.

I'm concerned about basically everything: fuel economy, ease of repair for me to do or cost of repair if it's beyond me. Also upgradability, reliability, power and availability of parts as they are getting to be old engines.

What do you guys think would be the better decision?

[TJones]

The mechanical would be easier to work on. Also consider what transmission and rear axle ratio is in each bus.

Ted

[brokedown]

All else being equal it's a no brainer. Mechanical engine for the win. Instead of a complex array of ECMs and sensors, a mechanical cummins can run with a single wire having power.

In trade, you lose the diagnostics features of all those sensors, which may or may not be useful. My first bus is an electronic T444E and my new bus has a mechanical 5.9.

[Bon Voyage]

any idea what's better on fuel? and upgradable?

[TJones]

The electric may have a slight advantage on fuel economy because the injection is electronically controlled. The electronic version may be able to be reprogramed for a higher hp/torque. The mechanical pump can be adjusted for more hp/torque. Electric ISC with the CAPS pumps did have problems with pump failures. The CAPS were used until the ISC switched to common rail injection. The mechanical pump would be likely be more reliable.

Ted

[magnakansas]

more power is to be had with turbo and fuel pump modifications, also so camshaft and valve springs, then in order not to blow headgaskets, something called "o ringing" the cylinder head/ engine block. Both engines can be tuned for more power. mechanical is done with parts and knowledge, the electronic, software at first, then mechanical changes. the electronic is likely to burn cleaner, but a well tuned mechanical will be very very close to the same. The additional parts in an electronic fuel system killed that for me, but I am in a unique position of starting with a bus that had no drive line to start with, and even if it did, I had already decided what engine and transmission I was going to use.

[Mekanic]

Originally Posted by TJones

The electric may have a slight advantage on fuel economy because the injection is electronically controlled. The electronic version may be able to be reprogramed for a higher hp/torque. The mechanical pump can be adjusted for more hp/torque. Electric ISC with the CAPS pumps did have problems with pump failures. The CAPS were used until the ISC switched to common rail injection. The mechanical pump would be likely be more reliable.

Ted

X2 on that

I love my 1994 12V 5.9L (NO computer)

[Tango]

Make that FAR more reliable.

[TJones]

I've been doing some research on the early ISC CAPS injection pumps. They will last longer if a low pressure fuel pump around 15 psi is placed at the fuel tank. This pushes fuel to the CAPS pump preventing it from pulling in air if there is a leak in the fuel line. It also pushes more fuel through the CAPS pump which improves cooling of the pump. I havn't had a chance to check my bus to see if it has an additional pump but it does have a fuel filter next to the fuel tank so I'm thinking it might.

Ted

[Bon Voyage]

I ended up getting a 2001 bus with the caps system so hopefully I won’t have any problems.

I asked Cummins if they could increase the power in it but after checking into it the guy said they can’t without replacing camshaft, pistons and some other things. They put some lower grade parts in the lower power engines to make them more affordable. 260 HP and 660 torque will have to do I guess.

[Bon Voyage]

Originally Posted by TJones

I've been doing some research on the early ISC CAPS injection pumps. They will last longer if a low pressure fuel pump around 15 psi is placed at the fuel tank. This pushes fuel to the CAPS pump preventing it from pulling in air if there is a leak in the fuel line. It also pushes more fuel through the CAPS pump which improves cooling of the pump. I havn't had a chance to check my bus to see if it has an additional pump but it does have a fuel filter next to the fuel tank so I'm thinking it might.

Ted

That’s interesting. I’ll have to read more about this too. Do you have any links Ted?

[Tango]

If it is a 5.9 that is nonsense. You can add nearly 50 hp with a screwdriver and no parts on a 4BT. More on a six. Check out the many Cummins forums (such as 4BTswaps.com). Between the smoke screw and timing you can do a surprising upgrade and often pick up a few mpg's in the process.

[EastCoastCB]

Originally Posted by Tango

If it is a 5.9 that is nonsense. You can add nearly 50 hp with a screwdriver and no parts on a 4BT. More on a six. Check out the many Cummins forums (such as 4BTswaps.com). Between the smoke screw and timing you can do a surprising upgrade and often pick up a few mpg's in the process.

See thread title.

[TJones]

Originally Posted by Bon Voyage

That’s interesting. I’ll have to read more about this too. Do you have any links Ted?

Here is a thread discussimg the problem.

Repeating CAPS Failures - Need Help - iRV2 Forums


Ted