3B Turbo Injection Timing

[bblawless]

Hello everyone. I just moved up to a 3b in my bj40 (from a B) and I brought my turbo with me. This new engine seems to be in great shape, and I’d like to do everything in my power to increase its lifespan. Only thing I’ve played with so far is the fuel. I did on my B as well, and was always chasing egt temps…eventually I’m going to run a water to air intercooler, but not for a few months at least. Someone told me it would be wise to dial in my injection timing now that this 3b is running a turbo. Can someone shed some light on this? The pump is currently on the factory timing marks on the pump/gear case. I’m running 12lbs of boost at the very most when on the highway, and my temps are manageable, but I’d like to lower my numbers to something more conservative and safe. Would appreciate any input, thank you!

 

[stevebradford]

You need to retard the timing as the boost from the turbo increases the compression and can cause early detonation.

It probably won’t help lower your Egt numbers but it will help keep unnatural forces off your crank.

For a non Intercooled 3b 12psi is pushing the egts high here on the hilly island and rest of BC from my experience.

I recommend a small low rpm spooling turbo with a wastegate and keeping the boost to under 10psi. Or intercooling it and still only making 12psi or you will run into heat issues on those 5 kilometre 6-10% hill climbs.

Also something important of note I feel is I did some testing on the 60 series that has a larger intake for the factory air can than the 40 series and I was pulling a vacuum in there under boost so I upgraded the air box inlet.

Post in thread 'Some info saved'

Nov 18, 2023

Sorry this is for the Diesels:

One random day the thought occurred to me that my non intercooled turbo 3B might not be getting all the air it could use at full send threw the stock air cleaner.

Conveniently I found my air cleaner lid had this nipple I never noticed before seemingly perfect for this test.

A carburetor vacuum gauge slipps right on

Top picture at idle, bottom picture is anything over 1600 rpm. So I’m pulling around a 1/2 psi negative pressure threw the stock air cleaner at anything over 1600 rpm.

A couple things might help...

• stevebradford

• 

 

[Dougal]

Retarding timing may make it too hard to start. This is climate/temperature dependent though. I definitely wouldn't advance the timing. It can be tempting and delivers more power but increases stress on the engine a lot.

 

[bblawless]

You need to retard the timing as the boost from the turbo increases the compression and can cause early detonation.
View attachment 4189317
It probably won’t help lower your Egt numbers but it will help keep unnatural forces off your crank.

For a non Intercooled 3b 12psi is pushing the egts high here on the hilly island and rest of BC from my experience.

I recommend a small low rpm spooling turbo with a wastegate and keeping the boost to under 10psi. Or intercooling it and still only making 12psi or you will run into heat issues on those 5 kilometre 6-10% hill climbs.

Also something important of note I feel is I did some testing on the 60 series that has a larger intake for the factory air can than the 40 series and I was pulling a vacuum in there under boost so I upgraded the air box inlet.

Post in thread 'Some info saved'

Nov 18, 2023

Sorry this is for the Diesels:

One random day the thought occurred to me that my non intercooled turbo 3B might not be getting all the air it could use at full send threw the stock air cleaner.

Conveniently I found my air cleaner lid had this nipple I never noticed before seemingly perfect for this test.

A carburetor vacuum gauge slipps right on

Top picture at idle, bottom picture is anything over 1600 rpm. So I’m pulling around a 1/2 psi negative pressure threw the stock air cleaner at anything over 1600 rpm.

A couple things might help...

• stevebradford

• 

Thanks Steve. I’m working from home today, so I will be retarding the timing before I hit the highway this afternoon…will report back. After looking through your thread I also do suspect in having restriction issues at my factory air cleaners inlet. Time to get the grinder out!!

 

[stevebradford]

I have experimented with timing advanced and retarded on the 3B and it between it having very little adjustment and being a tractor motor I never noticed a difference. With good compression it starts just fine with the timing slightly retarded.

The main reason for retarding the timing when adding a turbo is as we know diesels run by compressing a fuel air mixture until it explodes.

Further increasing that compression ratio by fitting more air and fuel into the cylinder with a turbo causes that compression point of ignition to happen earlier.

The ignition point should happen slightly before the piston reaches top dead centre. If your compression ratio is higher from adding a turbo that ignition happens earlier in the piston stroke it will push against the up coming piston robbing power and causing shock forces on the crank and rods.

Retarding the timing is just moving that ignition point back to just before that piston is reaching by top dead centre.

 

[seapotato]

Yeah that super long hose to the air filter is pretty restrictive. I opened mine up too and everything was noticeably better. Particularly how quickly the boost comes on.

I also retarded the timing a bit. How much wasn't terribly scientific. Likely copied what someone did in this section circa 2005 haha


There's also a trick with playing with the hoses on the intake butterfly. Rotating the fitting with the hole changes the throttle response noticeably. Not everyone likes the change, but it works on my tired old 3b.
There's a thread about it here somewhere, but here's a pic of what I'm talking about. The thread explains it in more detail, I just finished a graveyard shift so if I tried to explain it I'd just confuse myself.

Mine is set around 12 psi which is probably a bit too much, but with the IC my egts are tolerable if I'm not stupid on hills.
I don't worry about it with me driving, but I do cringe if the lead footed woman takes the truck out

I'm in cedar, give me a shout if you're up this way.

 

[bblawless]

So i made a couple changes, i retarded my timing and modified my airbox until I can make a proper pipe that runs to the front of the bay, but for now it’ll work. Before I retarded the timing it was actually a little advanced from the mark, so the truck runs a fair bit different now. I can’t tell if it’s got less power, kinda seems like it, but it does run quieter. A little bit more “knocky” on startup, so maybe I should bring it back a hair? Hard to tell..

The airbox mod made a world of different, turbo spools much faster now and my egts are noticeably lower, but I still plan on doing a water-to-air setup at some point. Once I get bored again, or until the next time I hit the Malahat lol

Probably pulling a decent amount of hot air, but I’ll get to it…

Current timing setting…thoughts? Too retarded? Looks pretty comparably to the pic @stevebradford posted above

 

[stevebradford]

Nah I love it. The adjustment setting looks good. If anything you have it nice and retarded now.

At idle it’s slightly retarded ready for the extra compression when the turbo spools and forces more air in under load that inadvertently advances the timing.

If you feel you lost anything power wise I would focus more as you already are on intake/exghust efficiency such as intercooling. You will make that power up by other means and have that power exactly when you need it like pulling a hill with a load.

Seapotato and I experimented extensively with the throttle body Venturi tuning. I think he like likes it still but I put mine back to stock. It does make a noticeable difference but in my opinion the difference it makes is when you feather the peddle it just goes to wide open throttle faster. To me that makes parking lots and low range crawling worse. I don’t mind having a deadish 1/3 fuel peddle feeling, I can get to WOT by pushing just a bit more to the floor if I want.

But if you want to try it all you need to do is turn this top Venturi tube opening in the throttle body from stock hole up to more horizontal.