Project: The New CDD Shop Truck

[Goose_ss4]

Definitely a skill my friend. Oh and follow up on my bp. At idle its 40psi and at a hard pull 130 psi. But that is what the computer sees so the tune writer could change those parameters a bit and can be slightly squed. My point was I wouldnt worry to much about high back pressure.

 

[79jasper]

Yep, sct screwed something up. Yours isn't the only one. Still reads in kpa, even if you have psi selected.
You could use the datalog function, then screenshot/copy it from your computer, but that's a bit more involved. Lol
KOEO map, ebp, and baro should all read about the same.

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[Thewespaul]

So about 20 psi at wot? That seems awfully low for a vgt turbo

 

[79jasper]

While most of us know how a vgt works, here's a good post on the more "control" side of things. While that seems like a fairly low ebp reading. It sounds about right.

The ebp:boost ratio numbers get thrown around a lot without much explanation. Also you really need a mechanical boost and ebp gauge to know what is going on.


There is a common misconception that vgt turbos "always" run higher ebp:boost ratio as opposed to non-vgt turbos. But that is not true. They can and will run a higher ebp:boost ratio when spooling the turbo (only if you desire and command it). You can pick your ebp:boost ratio with a vgt turbo and adjust this through tuning. I have multiple tunes that run at different ratios. (it has more to do with desired ebp or desired boost and not necessarily the actual ratio)


Most people want faster spooling turbos down low, so when you mash the throttle you can see upwards of 20:1 ebp ratio (20psi ebp:1psi boost). But that usually only lasts for a split second until the turbo is spooled. After that split second the ratio drops WAY down to like 1.5:1 (15psi ebp:10psi boost). That is how vgt works. You can manipulate the vanes to create excessive back pressure for a split second which will spool the turbo. A 20:1 EBP:boost ratio will not hurt the motor at those small boost/ebp levels. Heck 20-35psi of ebp is completely normal and wont hurt anything.

When cruising I have tunes that run at a 1.7:1 ratio (10psi ebp and 6psi boost) which seem to spool faster and be much more responsive with much less smoke output. I also have some tunes that run 1:1 ratio (3psi ebp and 3psi boost) Those tunes are usually less responsive and are a little smokier... Interestingly enough they both run about the same egts at the same cruising speeds.


At WOT most people I know see right around 1:1 through 1.2:1 ratio (unless they are throwing a ton of fuel at it). On long hard runs the ratio can start to creep up a little bit to around 1.3:1, which is completely normal and safe. It is the high ratios with higher ebp/boost numbers that you need to worry about. A 2:1 ratio at (90psi ebp: 45psi boost)... that can blow your motor/headgaskets... but that does not happen with vgt turbos unless something is wrong (stuck vanes, bad tuning, etc). The vanes will adjust to keep that from happening.

So...

Cruising usually around 1:1 - 2:1
Mashing throttle and spooling up the turbo can see upwards of 20:1
1/2 throttle acceleration after turbo is spool can see around 1.5:1
WOT runs after turbo is completely spooled usually see around 1:1 - 1.3:1

But it all depends on which tune and turbo you are running

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[Goose_ss4]

Yea I agree with the sct . But I think that is mostly because of the custom tune. Tune writers sometimes increase the value of ebp to get the computer to give full fuel and open the vanes on the turbo all the way up. I was mostly using that as an example that it was 90 point swing on that scale.

 

[79jasper]

Yep, I agree that after tuning, the values can be skewed as well.
Some 6.0's don't even report ebp. (03's only iirc)

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[Thewespaul]

You guys reviving this thread got me itching to turn some wrenches on the shop truck, and I needed some better pictures of the 38 gallon tanks installed for the website since they weren’t selling very well after the initial release. So, pulled an all nighter last week and got the bed pulled off, stripped all the stock lines off the frame, pulled both tanks, prepped and painted the frame, and installed the tank the following night. Plan is to run two GSL392, with a 1/2” feed and return.

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[IDIBRONCO]

Plan is to run two GSL392, with a 1/2” feed and return.

Well that sure ought to give you plenty of fuel flow. Hopefully this engine will hold up long enough for you to take full advantage of it.

 

[IDIBRONCO]

and I needed some better pictures of the 38 gallon tanks installed for the website since they weren’t selling very well after the initial release.

I'm still planning to order one this summer after the heating bill has gone down.

 

[Thewespaul]

All the fuel, the ip I’m going to be putting on it is going to require a base pressure around 100 psi and going to need a lot of volume to be able to maintain that, so running two pumps and staging them should work well for that.

 

[Booyah45828]

I don't remember if it's been said, but are you planning on eliminating the transfer pump in the injection pump when this goes back together?

 

[IDIBRONCO]

All the fuel, the ip I’m going to be putting on it is going to require a base pressure around 100 psi and going to need a lot of volume to be able to maintain that, so running two pumps and staging them should work well for that.

Good Lord! If you're doing this to the shop truck, I can't imagine what you'll do for the fuel in the drag truck. Maybe just put a 20 gallon drum on the top of the cab and run a 3" line straight to the IP?

 

[Thewespaul]

I don't remember if it's been said, but are you planning on eliminating the transfer pump in the injection pump when this goes back together?

It might be needed to control this pump, but I’m going to try and retain the factory transfer pump if I can.

 

[Thewespaul]

Good Lord! If you're doing this to the shop truck, I can't imagine what you'll do for the fuel in the drag truck. Maybe just put a 20 gallon drum on the top of the cab and run a 3" line straight to the IP?

The race truck is getting twin .450 db2s

 

[IDIBRONCO]

Two engines? Or two IPs on one engine? Either way, I can't wait to see this!