LB7 modification: Daily Driver/Tow Duramax

[Bersaglieri]

Years back I had a LB7, I was dumb, I stacked [Edge/Predator], beat it up, and traded it in on a 12v Dodge. Now I've got another LB7 and I'm gonna try and do it right. This thread exists to discuss and document each step of the modification of this truck. It's a daily driver/tow truck so the factory turbo and bottom end will be utilized for as long as possible. This 2002 CC/SB truck was purchased with 297k and it stock to the bone.

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December 2013:
I got a little crazy for Christmas and since it's technically the woman's truck I bought a few things for her truck while the sales were still on. I decided to address the exhaust flow.

Exhaust:
BD Full Bore Manifold: $120 shipped on sale
Magnaflow SS wrapped downpipe: $120 shipped on sale
3.5" Muffler Delete Pipe: $50 shipped

The goal here was to get the best flowing exhaust setup from the heads back spending the least amount of money. I don't care about big pipes or shiney tips, the exhaust choice was all about performance to dollar ratio. I [and others] didn't feel that a 4 or 5 inch exhaust was worth the investment at my anticipated power levels AND without addressing the factory downpipe. Now you're asking, "why the BD manifold then?" At it's original price I wouldn't have considered the BD Manifold. However, at $120 it's not much over the dealer price vs a LMM/LML manifold and it's arleady tapped for the EGT probe. I remember my manifold cracking around the tapped hole on my old truck. Between the tapped hole and the alleged flow gain and "cylinder balancing" it should be worth it.


Gauges: I'm undecided on 1500* vs 1800* pyro gauge, the 12v outgrew a 1500* one pretty quick. However the girl would probably benefit from the color coded ISSPRO pyro. I can't remember my old truck getting over 1400 degrees pre-turbo, but that was like 8 years ago. Probably just get a 60lb boost gauge and one of those two pyro. No reason for a trans temp or anything else is there?

Intake: I've never been big on cold air intakes on most light diesel trucks. I've read the factory one can handle 500hp with ease, however I'm thinking about constructing one of those cheesy PVC intakes and using the factory airbox like I had on my old LB7 truck. Anyone have thoughts or opinions on this?



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[Chris Tobin]

I like the Banks cold air intake on my LB7. It installed easy and as directed has a huge filter and no flow restrictions and seems to isolate the intake air well from engine bay heat.

I would suggest you get a Fleece turbo intake elbow as well as intake heater delete plug. The factory intake elbow is restrictive and they machine it out to match the turbo and the intake heater is not needed and it make a good place for the port for your boost gauge.

 

[1pieceatatime.]

Just do the PPE Airbox mod. A cold air intake does offer a ton of gain on an LB7 The ported intake horn is a good idea. I'm not sure what fleece charges for the one they sell, but I would definitely shop around some. I bore intake horns out for local guys on occasion.

You really just need to decide what your goals are. 400RWHP is about all a stock 5 speed allison is going to tolerate, even less if its got some hard miles on her.

A max effort tune, a lift pump and a built trans will make an LB7 a night and day different animal. Head gaskets will probably be a concern if they haven't been done/updated to new style gaskets.

Oh, and if your going to run any kind of built trans tunes, a 1500* pyro might not be adequate.

 

[Bersaglieri]

I like the Banks cold air intake on my LB7. It installed easy and as directed has a huge filter and no flow restrictions and seems to isolate the intake air well from engine bay heat.

I would suggest you get a Fleece turbo intake elbow as well as intake heater delete plug. The factory intake elbow is restrictive and they machine it out to match the turbo and the intake heater is not needed and it make a good place for the port for your boost gauge.

I'm not sure I could run any Banks parts on my truck, however it seems I may have to consider a cold air kit. Someone mentioned a larger intake elbow, but I never looked into them. What gains are we talking on that and the heater delete, I'm looking for MPG increases and EGT reductions.

Just do the PPE Airbox mod. A cold air intake does offer a ton of gain on an LB7 The ported intake horn is a good idea. I'm not sure what fleece charges for the one they sell, but I would definitely shop around some. I bore intake horns out for local guys on occasion.

You really just need to decide what your goals are. 400RWHP is about all a stock 5 speed allison is going to tolerate, even less if its got some hard miles on her.

A max effort tune, a lift pump and a built trans will make an LB7 a night and day different animal. Head gaskets will probably be a concern if they haven't been done/updated to new style gaskets.

Oh, and if your going to run any kind of built trans tunes, a 1500* pyro might not be adequate.

I'm curious about the gains on the cold air intakes, perhaps I dismissed them too soon. But I feel like the intake elbow and heater delete aren't going to net the performance to dollar ratio I'm looking for.

Right now I have mild goals. I don't plan on anything more than economy and tow tunes for years not months. Unless the Allison gives up, but even then, I'm trying to avoid doing what I did with the 12v, getting power crazy. Like I mentioned above, I'm interested in increasing MPG and keeping EGT's in check for towing. This truck is replacing a Tahoe that was sucking us dry at the pump for daily driving/long trips. Towing with a hopped up 12v isn't ideal when you get into altitude and/or steep grades. I'm hoping the LB7 can fill the daily driver spot and share some towing with the 12v.


I'll read up on the head gaskets, I'm pretty sure they are factory. When should I worry about those, boost levels or ??
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[1pieceatatime.]

I'm not sure I could run any Banks parts on my truck, however it seems I may have to consider a cold air kit. Someone mentioned a larger intake elbow, but I never looked into them. What gains are we talking on that and the heater delete, I'm looking for MPG increases and EGT reductions.



I'm curious about the gains on the cold air intakes, perhaps I dismissed them too soon. But I feel like the intake elbow and heater delete aren't going to net the performance to dollar ratio I'm looking for.

Right now I have mild goals. I don't plan on anything more than economy and tow tunes for years not months. Unless the Allison gives up, but even then, I'm trying to avoid doing what I did with the 12v, getting power crazy. Like I mentioned above, I'm interested in increasing MPG and keeping EGT's in check for towing. This truck is replacing a Tahoe that was sucking us dry at the pump for daily driving/long trips. Towing with a hopped up 12v isn't ideal when you get into altitude and/or steep grades. I'm hoping the LB7 can fill the daily driver spot and share some towing with the 12v.


I'll read up on the head gaskets, I'm pretty sure they are factory. When should I worry about those, boost levels or ??
.

The cold air intakes DON'T offer a ton of gain. Sorry about the typo. As for the muffler delete pipe, for the $279 you can get a muffler less 4" MBRP for, I would have gone that route.

The factory gaskets on LLYs and LB7s "expire" I guess you could say. Torque to yield head bolts stretch over time, and the original design riveted together gaskets don't help matters. Its more of a when than an if with the kind of miles you have on your truck. Not to worry you, BUT many a person have bought a Dmax in the early stages of headgasket failure and not realized it.

 

[Bersaglieri]

Sorta late for me, but what are the early signs?

Here is my thought process on the MBRP. What would be the gain for with the extra 1/2 inch? What is that gain vs the $225 increase in price. I'm not saying my logic is correct, but I guess rather than jump to 4" like I did with my first LB7, I wanted give the muffler delete a shot. Then a buddy and I were thinking that $280 would be better spent on the downpipe, muffler delete, and maybe the manifold. I'd really like to do a before/after dyno and EGT documentation just to see what it would net me vs just a 4" MBRP, but I don't know of any diesel dynos in this area.

So leave the intake alone, maybe port the air box. Are we thinking the PVC tubing would nether hurt nor help?

 

[1pieceatatime.]

Sorta late for me, but what are the early signs?

Here is my thought process on the MBRP. What would be the gain for with the extra 1/2 inch? What is that gain vs the $225 increase in price. I'm not saying my logic is correct, but I guess rather than jump to 4" like I did with my first LB7, I wanted give the muffler delete a shot. Then a buddy and I were thinking that $280 would be better spent on the downpipe, muffler delete, and maybe the manifold. I'd really like to do a before/after dyno and EGT documentation just to see what it would net me vs just a 4" MBRP, but I don't know of any diesel dynos in this area.

So leave the intake alone, maybe port the air box. Are we thinking the PVC tubing would nether hurt nor help?

You are wasting your time with the PVC tubing. If you look at the way a stock exhaust bends and flows VS and aftermarket, thats a contributing factor to your gain. The downpipe isn't even remotely worthwhile on a stock trans no lift pump truck.

 

[WhitetailAddict]

I would get an Autometer pyrometer and boost gauge, swiss cheese the airbox, put a 4" straight pipe exhaust on it, an LML manifold (if you're concerned) and write a good tow tune for it.

 

[6spdCR]

Without typing a book here let me just say that with those miles and in anticipation of towing with it save as much as you can to put towards head gaskets and or fuel injectors if it hasnt had a set in the last 100000 miles. Soot in the coolant or a darkened coolant degas bottle is a common sign if the beginning of head gasket failure. If somhow they are still in good shape you are lucky because I have studded a ton of lb7 trucks with under 150k on them that were stone stock.

Sent from my SPH-L720 using Tapatalk 2

 

[Bersaglieri]

You are wasting your time with the PVC tubing. If you look at the way a stock exhaust bends and flows VS and aftermarket, thats a contributing factor to your gain. The downpipe isn't even remotely worthwhile on a stock trans no lift pump truck.

I'm not trying to be disrespectful at all because clearly you have more experience with these trucks than I. But, aren't the last two statements you made contradicting each other? I mean wouldn't bends and pipe ID help at the down pipe as much or more than under the truck bed?

Without typing a book here let me just say that with those miles and in anticipation of towing with it save as much as you can to put towards head gaskets and or fuel injectors if it hasnt had a set in the last 100000 miles. Soot in the coolant or a darkened coolant degas bottle is a common sign if the beginning of head gasket failure. If somhow they are still in good shape you are lucky because I have studded a ton of lb7 trucks with under 150k on them that were stone stock.

Sent from my SPH-L720 using Tapatalk 2

Thank you for that information. It had injectors done about 30k ago, compression on the cylinders at the point were claimed to be in the 390's across the board. How ever I'll take a peek at the coolant and coolant tank tomorrow. I'm assuming that means they bust and leak into the cylinders rather than seep down the block? I hope I'm not doing head gaskets in the near future, but it's good to know what to watch out for.

 

[6spdCR]

Your welcome, another tell tale is residual pressure in the coolant tank after the truck has sat long enough for the engine to be at ambient temperature. You are correct in that Miramax head gaskets rarely leak externally. If anything you may notice disappearing coolant with no external leaks found. Glad the injectors were done recently, personally I like adding a lift pump, water separator and 2 micron filter in place of the expensive and marginal factory filter and primer pump. I prefer using a walbro 255 LPH pumP, return regulator and Baldwin filter bases to build a lift pump setup. It's about the same money all told as an air dog or Fass, but it will outlast either of those pumps and the filters cost half as much and are available anywhere.

 

[1pieceatatime.]

I'm not trying to be disrespectful at all because clearly you have more experience with these trucks than I. But, aren't the last two statements you made contradicting each other? I mean wouldn't bends and pipe ID help at the down pipe as much or more than under the truck bed?
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You are dealing with 2 different issues. Getting air in and getting air out.

500RWHP is easily obtainable with the factor air intake setup. A PVC setup is going to have more turbulence than the factor intake.
Witht he exhaust system. Larger exhaust both gets rid of the factory bends and creates more room for volume of flow.

I'm not saying you need 4" and your muffler delete is inadequate. But IMHO you are pissing into the wind swapping that downpipe out with that setup.

Your welcome, another tell tale is residual pressure in the coolant tank after the truck has sat long enough for the engine to be at ambient temperature. You are correct in that Miramax head gaskets rarely leak externally. If anything you may notice disappearing coolant with no external leaks found. Glad the injectors were done recently, personally I like adding a lift pump, water separator and 2 micron filter in place of the expensive and marginal factory filter and primer pump. I prefer using a walbro 255 LPH pumP, return regulator and Baldwin filter bases to build a lift pump setup. It's about the same money all told as an air dog or Fass, but it will outlast either of those pumps and the filters cost half as much and are available anywhere.

They push the coolant out the overflow, so they do push the coolant out externally, but it usually gets noticed in the wheel well if the drip/wetness gets noticed.

 

[Bersaglieri]

Your welcome, another tell tale is residual pressure in the coolant tank after the truck has sat long enough for the engine to be at ambient temperature. You are correct in that Miramax head gaskets rarely leak externally. If anything you may notice disappearing coolant with no external leaks found. Glad the injectors were done recently, personally I like adding a lift pump, water separator and 2 micron filter in place of the expensive and marginal factory filter and primer pump. I prefer using a walbro 255 LPH pumP, return regulator and Baldwin filter bases to build a lift pump setup. It's about the same money all told as an air dog or Fass, but it will outlast either of those pumps and the filters cost half as much and are available anywhere.

I'll have to keep a close eye on this, I'll also pick the previous owners brain on if it's got factory gaskets. On filtration, I do have 2 aftermarket filter heads, with the spin on filter/seperator that I bought for a belt driven fuel pump project on the 12v. The WIX fuel filter I bought yesterday for the LB7 said "7 microns". I'm not sure what's recommended but WIX has always done me right in the 12v.

You are dealing with 2 different issues. Getting air in and getting air out.

500RWHP is easily obtainable with the factor air intake setup. A PVC setup is going to have more turbulence than the factor intake.
Witht he exhaust system. Larger exhaust both gets rid of the factory bends and creates more room for volume of flow.

I'm not saying you need 4" and your muffler delete is inadequate. But IMHO you are pissing into the wind swapping that downpipe out with that setup.




They push the coolant out the overflow, so they do push the coolant out externally, but it usually gets noticed in the wheel well if the drip/wetness gets noticed.

I wasn't clear. I'm wasn't arguing for the PVC intake, it was more about the exhaust. If the factory intake can support 500rwhp, I'm happy wit that, less time and money spent.. In regards to the exhaust I was trying to say is that if you argue that the bends/flow reap benefits from the downpipe-back 4" exhaust, then the same could be argued about the factory downpipe, right? Now I've done no actual testing to back this up, but when I was looking for pictures to compare I did find this article:

http://www.thedieselpage.com/reviews/magnaflowc.htm

Here is the picture I wanted to explain my point with:

I think the factory muffler is the most restrictive point in the factory downpipe-back exhaust. This article seems to show rather minimal gains at stock and tow tune levels with a Magnaflow exhaust. I feel that for mild performance a muffler delete would reap similar gains for hundreds less than a full 4" setup. I then thought that the downpipe itself would be the next most restrictive piece in the factory turbo-back system. However, it seems I was looking at the EGR LB7 pipe and not the 49 state version. Here are some pictures for anyone else learning like me.

49 State:

EGR/California:

Vband style:

Both aftermarket:

The 49 state LB7 one doesn't seem as bad I what I thought, however it's hard to determine in the pictures how restrictive it as compared to a nice round 3" pipe. Tobin had my psyched up about these downpipe gains. But like you said, air in/air out, and if a BD Manifold and 3" downpipe can make the engine more efficient throughout the RPM range, that's really what I'm looking for because efficiency = mileage. Are there gains to be had there, it looks like it, but I don't know, that's why I'm discussing it. Maybe not worth $120 at my power levels. I really wish I knew before going through the hassle if it would drop EGT's by even 50*. Little amounts like that add up when towing. But, I'm ok with cutting out wasteful spending if it saves money on things like gauges or tuning.


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[JoshH]

I've never really understood the need for the high temp egt gauges. You're either watching the gauge to keep it cool, so you would already be doing something to bring the temps down before it got close to burying a 1500 or 1600 degree gauge, or you're racing or sled pulling or doing something where you don't really care how hot it gets for a few seconds. I don't see why you would need to see it got to 1900 degrees unless its just for morbid curiosity.

 

[TheBac]

I'd have left the factory airbox on it, you are good to around 500rwhp with the stocker. Maybe swiss-cheese the box for more airflow.
IMO an aftermarket downpipe is waste of money except to replace Cali downpipe.
Last I knew, LML manifold was around $60, but if you're ok with paying double, then fine.

Add a cheap PPE boost valve and port the intake horn and leave the rest of the turbo alone. Add a lift pump for fuel.

Gauges are gauges. 50psi boost and 1500 pyro are fine. If you are pushing the stock LB7 turbo past 32psi its not going to last long. If you are running over 1300 egt all the time, the engine is going to die a quick death, too.

 

[Bersaglieri]

It still has the factory airbox. I ported the airbox on my old LB7, seems that's still the way to go under 500hp, which I what I thought originally.

It looks like I was referencing the wrong factory piece to justify a downpipe, however Chris Tobin's notes on upgraded downpipes from the other thread had me thinking there were gains to be had. The cost for a LML manifold from the dealer with an employee discount was $75 plus tax and shipping due to non-stock item. It was going to be close for the BD sale price, I figured the pyro port covered the cost difference.

What does the PPE boost valve do?
What is involved in porting the factory horn? We've home ported throttle bodies and stuff.

On the gauges I was just curious what most people were using. My 12v had to be upgraded to 100psi and 1800* from 60psi and 1500* ones. I didn't think LB7's ran that hot, but when ordering 1500 vs 1800 the price is the same so I figured some head room wouldn't hurt.

 

[LSGUNSS]

It still has the factory airbox. I ported the airbox on my old LB7, seems that's still the way to go under 500hp, which I what I thought originally.

It looks like I was referencing the wrong factory piece to justify a downpipe, however Chris Tobin's notes on upgraded downpipes from the other thread had me thinking there were gains to be had. The cost for a LML manifold from the dealer with an employee discount was $75 plus tax and shipping due to non-stock item. It was going to be close for the BD sale price, I figured the pyro port covered the cost difference.

What does the PPE boost valve do?
What is involved in porting the factory horn? We've home ported throttle bodies and stuff.

On the gauges I was just curious what most people were using. My 12v had to be upgraded to 100psi and 1800* from 60psi and 1500* ones. I didn't think LB7's ran that hot, but when ordering 1500 vs 1800 the price is the same so I figured some head room wouldn't hurt.

The PPE boost valve fool's the wastegate in to seeing less pressure so it opens later creating more boost. With this I can see 30PSI at will on my big tune.

I ported my factory horn myself and opened it up quite a bit. I also notched the bottom bolt like the aftermarket jobs to help with installing it. Here are some pics of my horn ported next to a stocker. All of these pics are before I polished it.


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[TheBac]

Ok, Ive seen those pics somewhere before.....DD perhaps?

Nice idea on notching the bottom bolt. That one is a PITA to install.

 

[JWhite]

IMO, run an adapter for a 2 micron Cat fuel filter. Run the stock airbox like everyone said, might as well install the delete pipe and downpipe since you already bought them. It'll sound better with that downpipe, and that's not a bad price on the BD manifold, no point in sending it back now! For cost effectiveness, install a single Kennedy fuel pump, no need for a fancy airdog/fass.

 

[Bersaglieri]

So it just delays the reading, can that be done with tuning on a LB7, or is it merely a mechanical metering? I run a spring pressured wastegate on my 12v, so I never messed with limiting the boost referencing.

Does the intake horn need porting throughout or is it just stepped at the ends? What improved with that modification, just peak boost or ?

TheBac:
I registered at DD and found some of your discussion on downpipes. Good info on the cross section area and noting that the Vband area is still a bottle neck on the aftermarket pipes. My gasser side sees that as the 'pushrod pinch' of the system. In general people don't analyze modifications at that level and I respect that. Most of those posts seemed older but did you ever try a 3" or make a 3.5" with a larger Vband?

I saw a few folks claiming 50-100* decreases in EGT's empty, despite the bottle neck. From a towing aspect, that's a notable gain in efficiency.

IMO, run an adapter for a 2 micron Cat fuel filter. Run the stock airbox like everyone said, might as well install the delete pipe and downpipe since you already bought them. It'll sound better with that downpipe, and that's not a bad price on the BD manifold, no point in sending it back now! For cost effectiveness, install a single Kennedy fuel pump, no need for a fancy airdog/fass.

I've got a filter head and a FF5320 2 micron Fleetguard filter already. Do I just run that between the factory filter filter and the pump? I just figured getting as many bottle necks out of the exhaust for the least amount of money would increase efficiency. I'll look up the Kennedy pump, I'm not exactly a big Airdog or FASS fan.


I really want to unchoke this exhaust ASAP, the delete pipe showed up yesterday, but I need to wait for gauges. I'm planning on as least doing EGT documentation on each change in the exhaust system. Factory empty, Factory towing, tuned empty, tuned towing.


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