600-650HP LBZ Build - Misc Questions - I'm a Virgin!

[Rooftop Special]

Hello Everyone,

First, thanks for providing such a great resource for "normal" guys like me to attempt something like this. I've done a fair amount of wrenching but nothing like this.

So I blew my LBZ pulling a 21k 5th wheel a week or so ago. I have decided to have the motor rebuilt. I’m going to take the engine out and install it myself. I have some questions I was hoping you guys could answer. I’ve been searching and searching but finally just decided to post to tie up loose ends.

I’m looking for 600-650HP and dependability while towing is a must. I know a stocker is the most dependable but….boring!

Here is what I’ve decided on (open to changes/would like opinions)


· -All the typical dmax machining to include keyed crank and cam.
· -I’ll have the heads machined and rebuilt.
· -Assuming all is good I’ll reuse the crank and cam
· -Wagler as-forged street connecting rods
· -Mahle Performance cast pistons
· -ARP head bolts
· - Have engine balanced

Here is what I have questions on


· -Do I need a new flexplate and/or balancer/damper?
· -I’m still not sure why the engine blew (haven’t taken the engine apart yet). I want to eliminate a bad injector. Is there a way to have injectors tested/refurbed out of the motor?


What else should I be replacing while the motor is out? I changed the water pump last year but not with a welded one. Should I do that? Any other hoses or hard to reach items that make sense to replace while the engine is out?

I want to do anything I can to reduce exhaust temps. I plan on a turbo back 4” exhaust thus far. Anything else. I probably won’t have any tuning done until I can do the transmission but want to have the engine ready.


Lastly when I go to seek out the 600-650HP can I accomplish this via good tuning or would I need bigger injectors, different turbo, etc.


Thanks in advance,

Casey

 

[DAVe3283]

Also curious why the engine blew. What are the symptoms now? Locked up?

You can make 600 HP on stock fuel and air as a max effort race type setup, but it won't be reliable. You will want bigger injectors (+50% or more will support 650 HP easily), and probably will need a bigger CP3 (or dual CP3s). You can send your injectors out for testing, but I would consider getting some larger units now, rather than spend money diagnosing old injectors you won't be using for long anyway.

You will want more air, especially if trying to tow with that power. A compound setup is usually nice for towing, and that will keep your EGTs down too. The guys on here probably have good advice for what size turbo to add, I'm more of a big single guy myself. A 71mm single will get you 660 HP, probably even a single S369sxe would hit your 600-650 HP goal.

When I built my motor, I reused the flexplate. Just look it over, if it is in good shape (no cracks or signs of stress), it should be fine. Some people like to upgrade, but I say wait until you break it. They are relatively easy to change later if needed.

I recommend getting a press-fit style damper, like the SoCal Diesel / ATI unit. Have the assembly balanced with that damper. My ATI damper makes the motor improbably smooth, and I run nearly solid motor mounts.

You can get a pinned or welded water pump. I have heard of more failures with welded pumps than with pinned pumps, so I went with a pinned pump with a clipped impeller. If you are keeping RPMs down near stock, you might be OK with a stock pump. It is the high RPMs that put huge backpressure on the pump and spin the shaft. A compound turbo setup won't require the RPM a big single does. However, for the couple bucks more to get a pinned pump, I'd do it and sleep better.

If you are expecting to be able to use 600+ HP while towing, you will need major improvements to the cooling. See James' (Chevy1925) [THREAD=35104]thread where he fights temperatures with big power towing[/THREAD]. It is a long read, but there is a TON of great info in there. Just remember, semi trucks have about the same 600 HP, but their radiators are gigantic. So keeping that much power cool with half the surface area isn't exactly easy...

 

[Chevy1925]

ill wish you best at towing at 600hp and keeping temps in check :roflmao:. not laughing at you, more with you cause well.... i have more money/time than id like to even think about in trying to keep things cool at 600rwhp while towing.

where are you located, outside air temp really dictates how much power you can push before you overload the cooling systems.

i have not seen someone tow gross weights of 26k+ on a bigger single and kept oil temps in check. bigger single means more rpm which heats oil up faster, twins add more heat to the oil due to second turbo heating it up so neither will really keep oil temps at bay without a big cooler. So pick your poison on compounding or bigger single turbo.

i would for sure do bigger injectors as well and a bigger single pump. duals create more return fuel and more heat in the fuel which comes back to bite you when towing unless again, you have a decent cooler

if i was buying new pistons, i would buy fingers oval bowl pistons. i would then know ill never have a piston issue even when towing/pushing engine hard and running high temps.




I will say this, running 600-650hp unloaded is NOTHING like towing at that same power level and actually using it. you would have to be around the 1k mark or more to see the same wear on the drivetrain unloaded and even then you probably wont see the issues you see when towing at that level. Your transmission is one of the weak links here and you need very healthy internal hard parts to keep the trans up. Mike has been into mine many times from the abuse and we think we got something that will last now assuming planetaries hold up. T-case bearings will show their worn head quickly, u-joints MUST be in a good plane and in good condition (id up to the 1480 if i were you, my 1450's were not happy after 30k and they were good spicer non greasable), axle wrap bars will be in your future to keep axle wrap under control when towing, bolt engine mount or merchant mounts, and more on top of all this.

 

[TheBac]

Guys, this is the person over on DP from AZ that was looking for advice to rebuild his engine. I had no idea he had an account here.

 

[Chevy1925]

Guys, this is the person over on DP from AZ that was looking for advice to rebuild his engine. I had no idea he had an account here.

Oh then he definitely has quite the challenge ahead of him

 

[Rooftop Special]

Guys,


Great info. Thanks you!


So the engine runs but has 0 compression in one cylinder and severe blow by. I wasn't monitoring exhaust temp and I know better. This is my 4th or 5th dmax. I know I had a bad boost leak for a while and got it repaired before this summer but who knows how long it was that way before I bought it. I bought this truck used at 185k and it has just over 200k now. I also had overheating issues last summer. I cleaned the stack and replaced the clutch but honestly things still got warm pulling 21k on a grade.


I live in Mesa, AZ so things are warm to say the least. A already reached out to Mike L and he knows what I want to do tranny wise.



By the sound of things I better de-tune for towing and use the 600-650HP for fun. I assume efi live with the selector switch will accomplish this?



How much additional HP could I run while towing without having to worry too much about these, what seem to be, endless issues while towing?


What issues would I have running bigger injectors but not running additional HP while towing? If fingers are really stronger than I'll spring for them but if there just for additional HP I thi k I'd pass as at some point mamma will find out how much I'm spending!

 

[Rooftop Special]

Guys, this is the person over on DP from AZ that was looking for advice to rebuild his engine. I had no idea he had an account here.

Yeah, it's me....the way you say it makes feel like I have leprosy!



It seems like people have more experiance building over here. I decided to do the install myself since someone here told me about a machine shop that's done a few dmax's.



Thanks guys,

 

[TheBac]

Didnt mean anything by it, other than to let the other guys know who you were.


For 600hp, I would personally use cut LB7/LLY pistons, Brian Crower or Wagler rods, balance the whole rotating assy, stud the heads, better valvesprings and fasteners for the valvetrain, one of Danville's upgraded LBZ turbos, a 10mm or 12mm CP3 and 100-over injectors.

 

[Ne-max]

I bet you have the common cracked piston.

 

[Rooftop Special]

Didnt mean anything by it, other than to let the other guys know who you were.


For 600hp, I would personally use cut LB7/LLY pistons, Brian Crower or Wagler rods, balance the whole rotating assy, stud the heads, better valvesprings and fasteners for the valvetrain, one of Danville's upgraded LBZ turbos, a 10mm or 12mm CP3 and 100-over injectors.

I know you didn't. I appreciate the help over there.


What are the negative impacts of running bigger injectors if I'm essentially on a stock tune while towing?


Is a bigger CP3 something I can do later down the road?

 

[Burn Down]

First off, Welcome!

Second, whats the budget you have to work with? Makes a big difference on what most will recommend:thumb:

 

[MAXX IT OUT]

ill wish you best at towing at 600hp and keeping temps in check :roflmao:. not laughing at you, more with you cause well.... i have more money/time than id like to even think about in trying to keep things cool at 600rwhp while towing.

where are you located, outside air temp really dictates how much power you can push before you overload the cooling systems.

i have not seen someone tow gross weights of 26k+ on a bigger single and kept oil temps in check. bigger single means more rpm which heats oil up faster, twins add more heat to the oil due to second turbo heating it up so neither will really keep oil temps at bay without a big cooler. So pick your poison on compounding or bigger single turbo.

i would for sure do bigger injectors as well and a bigger single pump. duals create more return fuel and more heat in the fuel which comes back to bite you when towing unless again, you have a decent cooler

if i was buying new pistons, i would buy fingers oval bowl pistons. i would then know ill never have a piston issue even when towing/pushing engine hard and running high temps.

James, how much of that 600+ HP do you think you use when towing. Granted you have twins, more aerodynamic drag, long grades and altitude to deal with, which increases load on everything. I am curious, because the only thing I really have issues with when i tow heavy on my biggest tune is EGT's, which if its under 1200, I don't worry about it.

 

[zakkb787]

Didnt mean anything by it, other than to let the other guys know who you were.


For 600hp, I would personally use cut LB7/LLY pistons, Brian Crower or Wagler rods, balance the whole rotating assy, stud the heads, better valvesprings and fasteners for the valvetrain, one of Danville's upgraded LBZ turbos, a 10mm or 12mm CP3 and 100-over injectors.

Bingo

 

[Chevy1925]

James, how much of that 600+ HP do you think you use when towing. Granted you have twins, more aerodynamic drag, long grades and altitude to deal with, which increases load on everything. I am curious, because the only thing I really have issues with when i tow heavy on my biggest tune is EGT's, which if its under 1200, I don't worry about it.

I’ve used all 1350ft lbs quite a bit but if temps allow, I’ll use wot a few times a trip. Mainly to get back up to highway speed, passing truckers, or the occasional tow race. I usually let it hold 5th and just torque the shit out of the truck to pull a grade instead of revving it if I don’t have to.

Dropping my power level to 475/500ish I used wot alot up the last grade coming out of camp verde. Heavy traffic and trying to get around slow guys that slowed me to 35. Did 4-5 pulls from 35 to 65. I missed the extra power beyond that.... I never saw over 1100 egt on that tune. On the 600hp tune I don’t see over 1350 at wot. That’s never been my issue. It’s the outside temps and heat I generate that becomes my fight.

Honestly, when it’s 65* and below and I tow the same mountains with same weight, I’m holding 5th gear at 70mph on ever grade at 45-50psi of boost and temps never get hot. That is a very strange feeling when the truck loads up like that for minutes at a time

 

[Chevy1925]

I know you didn't. I appreciate the help over there.


What are the negative impacts of running bigger injectors if I'm essentially on a stock tune while towing?


Is a bigger CP3 something I can do later down the road?

Depends on how big of an injector you go. Some will be ok, others not so much. Bigger cp3 can be done down the road but you may not hit your hp goal depending on turbo/s choice

 

[Rooftop Special]

First off, Welcome!

Second, whats the budget you have to work with? Makes a big difference on what most will recommend:thumb:

10k. But that includes fixing whatever caused the engine to blow which could be an injector?



So if I'm at 3500 in machining and assemble, 3500 on rods and pistons, 500 on a balancer, and 600 on head bolts I'm at 8100 and that doesn't include incidentals. I want to build to a reliable (within reason) 650hp. For instance I "know" (at least from what I've read) that I'm not doing a crank or an AF cam as that would be overkill. What I don't know is fingers really worth an additional $450 if I'm only building to 650hp?


I do however want to spend on internals now for the obvious reasons VS externals like turbos and injectors since I can more easily go back to those when I have more funds.


Thanks,


Casey

 

[Rooftop Special]

Depends on how big of an injector you go. Some will be ok, others not so much. Bigger cp3 can be done down the road but you may not hit your hp goal depending on turbo/s choice

The 650HP is an eventual goal. For now I just want to make sure I'm building the engine to reliably handle it.


Did you use Larry's for your builds?

 

[Burn Down]

10k. But that includes fixing whatever caused the engine to blow which could be an injector?



So if I'm at 3500 in machining and assemble, 3500 on rods and pistons, 500 on a balancer, and 600 on head bolts I'm at 8100 and that doesn't include incidentals. I want to build to a reliable (within reason) 650hp. For instance I "know" (at least from what I've read) that I'm not doing a crank or an AF cam as that would be overkill. What I don't know is fingers really worth an additional $450 if I'm only building to 650hp?


I do however want to spend on internals now for the obvious reasons VS externals like turbos and injectors since I can more easily go back to those when I have more funds.


Thanks,


Casey

Id skip the balancer and do fingers ovals and wagler or BC rods. I think that will eat up most of your 10K. If you have the funds buy a oil cooler or build your own.

Whats the mileage/age of the fuel system?

As other mentioned I'm sure you cracked a piston, LBZ/LMM like to do that.

 

[DAVe3283]

I don't know that I'd do Fingers pistons at 650 HP. I'm at 660 HP on Mahle cast and no issues. I've heard more than one person lament the smokey nature and efficiency of the Fingers bowl design for towing. It holds power great, but the trade-off seems to be fuel economy and haze at all times.

I have no first hand experience with them, but wanted to put the counterpoint out there to make your decision harder

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[20dmax08]

If you think your going to be at 10g already. Why not look into a short block? Waglers entry level is 9800 I believe. Or buy the rotating assembly for 5200. When my day comes that’s what I’ll be looking at and adding a girdle and af cam. Overkill for 750rwhp goal? probably but I like peace of mind. Do it once and do it right.


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