Timing for NA

[Booyah45828]

Hello folks, multiple questions here. First and foremost I have a 6.9 IDI, allison automatic in a school bus. 4 years ago I set injection timing at 9*btdc with a snap on mt257 pulse adapter and a snap on timing light. I just acquired a j33300 and checked it again today and it is currently at 9.5* btdc with the pulse adapter and magnetic pickup(way easier this way then with the snap on meter).

Anyways, bus runs great, but anytime I'm over 1/2 throttle there is a hint of black smoke and it gradually gets worse with full throttle being pretty smokey. I don't have a pyro installed, but with the smoke and being NA, I'll assume it's hot. (I have a isspro gauge, just no probe)

First question is whether or not there are different specs/opinions on NA vs Turbo timing? Most of what I read on here stated 8.5* but that seems to be put out by guys running turbos. What do the NA guys do as far as timing is concerned? Do you guys think that retarding the timing a few degrees would eliminate the smoke?

Secondly, a turbo would be a really nice addition to this thing. Being a school bus however, I don't think any of the standard truck kits will work due to the different manifolds and the trans/firewall. Anybody got a rayjay manifold and intake horn that they're willing to part with for a reasonable amount? I think that style kit should work with some fabrication.

Let me know what you guys think,
Thanks

 

[IDIoit]

you can put turbos anywhere. that's whats great about em

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[FORDF250HDXLT]

Timing is the same N/A as it is turbo according to the specs which is 8 BTDC plus or minus 2.I prefer 7 BTDC.

If your seeing black smoke out of the exhaust,then your feeding the engine more fuel than it can burn.You'll need to turn the fuel down until the exhaust is clear at WOT under load.Black smoke doesn't mean extra power,it just means your wallet will be lighter do to reduced fuel economy,there will be more cancer causing particulates floating in the air and you'll shorten the life of the engine.

 

[pelky350]

I would go back on timing just a hair, make sure air filter is clean. Even with original stock fuel a idi is going to make some smoke at wot nothing heavy but a light haze is normal.

 

[bbjordan]

Is the smoke something new? If it is, check/change the fuel filter. Low fuel pressure can cause the timing to get way retarded causing smoke and poor performance. Since you say it's when the fuel demand is high, this is when this symptom shows up.

Heads up guys! Fall is a great time for your yearly(?) fuel filter change. Beats changing it in winter.

 

[Macrobb]

Being N/A, check the air filter as well. Restriction makes a difference.

I'd play with the timing a little, see what feels stronger. Being as the IP and injectors are worn at this point, you might find a more advanced or retarded setting to work better. Adjust and drive.
The stronger it feels, the better the timing - the more power you are getting out of the air you have, which means the less the engine is fighting itself.

Then, turn down the fuel screw until you get rid of the smoke. Smoke = high EGTs, low fuel economy etc.

 

[Booyah45828]

Turbo is the goal, I just don't want to spend a bunch of money to do it. Idioit, where did you get the pieces to make your manifolds? What did it cost? There is an hx35 on the shelf I could probably use, but I imagine it's too small.

Smoke isn't something new, it's just more noticeable now that the exhaust is fixed and is actually making its way from under the bus. It's definitely more then a haze. Filters were all changed less then 600 miles ago.

Is there anyway to verify stock fuel rate? I've never modified it but it's anybodies guess as to what it is. I'll back the timing to 8 and see what it does.

 

[Dieselcrawler]

hypermax makes a kit for the s series international trucks, which your bus is.

 

[Booyah45828]

I've seen that kit, but at close to 3 grand, I think I'll go with other options before I'd go with that.

 

[Thewespaul]

Can you swap on some truck manifolds?

 

[Booyah45828]

Wow, I finally have an update for this. This is a 6.9 with an allison in a school bus, so the speeds will reflect that.

I backed the timing from 9.5 to 8.5 and took the bus on a 200 mile trip. Didn't notice any changes really. It ran fine but seemed to lack power and acceleration(could barely get to 65mph and wouldn't hold going up the slightest hill, water temp was 215 and oil temp was 235 at 65mph for reference). Fwiw 65 mph is right around 3000 rpm, so I would think it would run faster, just seemed to be maxed out on power.

After I got home. I read up some more on timing these engines and decided I would back it off some more and see what happens. So I backed the timing to 6.5. Took it for a trip and it's much better. Gets up to 70 mph from a dead stop in a little more then a mile, water temp is 200, oil temp is 190 at 65mph. Much better.

I still have smoke. It might be less at 6.5 then 8.5 or 9.5, but that's marginal. I'm going to assume it's either injectors or normal operation. I'll solve that with a turbo if I ever can find the manifold. (Those of you buying the rayjay manifolds for your twin turbo setups can stop, you're not going to finish the project anyways )

 

[Booyah45828]

Can you swap on some truck manifolds?

I probably could, But I still don't think I'd have the clearance between the firewall and the engine for the up and down pipes to pass through. I just don't think I'd have enough room for a 3 inch pipe with clearance.

A thought that I had was to run an oil less turbo remote mounted and water cool the cartridge some how. But I don't think those oil less turbos have any sort of durability to them.

 

[Thewespaul]

I probably could, But I still don't think I'd have the clearance between the firewall and the engine for the up and down pipes to pass through. I just don't think I'd have enough room for a 3 inch pipe with clearance.

A thought that I had was to run an oil less turbo remote mounted and water cool the cartridge some how. But I don't think those oil less turbos have any sort of durability to them.

You can remote mount it and run it with a seperate oiling system. Have the drain run into a half gallon tank mounted directly below the turbo, and have an oil pump suck from the bottom of the tank and feed the turbo. Built a drag car with this setup and worked great.

 

[snicklas]

If this is an International S-Series chassis, Hypermax makes a bolt on turbo kit for them.....

https://www.gohypermax.com/Catalog....38ac&sub=d8bbc7aa-ffba-42fc-9563-b87ff94dc813