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Back from the brink...help me locate and build my next 6.5!

Potluckslammy

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Ok folks, let me tell you what's going on, and bring you up to the minute...in case you hadn't been following my thread in 6.5 performance. (And I'm about to post in Introductions, too, if you care at all for my back-story). Original L65 in my 99 C3500 dually had been a pain in my rear for quite some time, although I very much enjoyed driving my rig when it wasn't. Looking for replacement, which will be used for frequent puttering, occasional light hauling and towing, and infrequent medium duty towing across Arkansas, Oklahoma and Texas...very infrequently longer trips into the deep South, likely in the heat of summer. Not many long, steep grades down here, but plenty of heat in the summer, and lots of open highway. Want to grade, and bullet-proof where possible. I guess my main purpose will be to build for Towing, rather than outright Performance. Would love a little more kick-in-the-pants, but efficiency and durability is of utmost importance...I'll likely be keeping this thing for a LONG time. Just escaped the noose and cancelled an order from US Engine Procrastination and Speculation! That wouldn't have ended well! Need some help, please!

Probably wanting a long block, preferably....Optimizer...clearanced and balanced....18.5:1 CR desired. Rather have the work done, and ready to install...as the local engine builder near my local is exceptionally proud of his work...quoting me $4K-$4.5K to rebuild my L65 (when I briefly thought it might be worthwhile to do so).

Here's a list of goodies I've already purchased while preparing for my now cancelled order from US Engine Plunderers: Aluminum 3-row radiator from Champion, New ACDelco 15-80690 21" Duramax fan, Hayden 2886 Fan Clutch, Fluidampr, Leroy Diesel Billet Crank Pulley, ARP Head Stud Kit, ARP Main Stud Kit, New AC Delco 251-603 Water Pump, 2 New 190degree stats (one from NAPA, one from Gates), New ACDelco 15158525 GM Original Equipment Engine Oil Cooler (to replace the one wrecked by a deer impact), 8 Marine Injectors rebuilt by TexasParts, Gates K061005HD belt, Stanadyne 39405 (Grey) PMD, 8 New AC Delco 60G glowplugs.

I think that's it! Don't think I forgot anything. OK, NOW I'm ready for the suggestions and leads to start pouring in! Hit me with some knowledge! Blast me with good advice! Hell....gut check me with constructive criticism if you have it! No sense rehashing what's been posted elsewhere, though...unless you want to link to something you think might be useful. I'll be looking for for technical advice later, most likely. Right now have to get a line on a quality replacement. Help me get'r did! And yes, I realize a built long block can likely be had with the studs installed, maybe the Fluidampr, too. If so, I'll resell the items I've already purchased...let'em go right here for a really good price, if anyone is interested! But first I have to find a quality builder, and that's where you guys come in...
 

Potluckslammy

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You need to talk to Chris....
I actually found the Twisted Steel website about the same time I found the Truck Stop...waslooking at his reduced CR pistons. Have been mightily impressed while window shopping...but it's just pictures and talk. And then...very pleased to see he's an active member here! Nice!

You won't need the marine injectors.
True. But the price was right, and TexasParts seems to be a reputable outfit. But then, what do I know? It won't hrt anything having them installed, right? Just a little higher pop pressure.

Can you afford a new optimizer long block?
Sell the new pistons, balancer, etc you dont need that come with it.
Afford? Well...what are we talking about, around $7100-$7400? It would chap my butt. But if that's what it takes. You have someplace in mind.
 

Twisted Steel Performance

Formerly: sctrailrider
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You can still order brand new long block from GM and get a 3yr warranty, BUT if you or someone else opens it up to modify things it voids the warranty.

I just shipped a P400 crate motor that I tore apart and heavily modified and sent it back to him, he is on this forum and I'm sure he will pipe up once he gets it installed...

but it's just pictures and talk. And then...very pleased to see he's an active member here! Nice!
Well, I have backed up my R&D with facts for years, and no, I'm not going to revel all my findings due to others copying for no spent money in their own R&D..

I guess with you being new to the site it's just talk, I'm good with that, I know my services are out of reach of a lot of people, but I do have a lot of folks out their that know what works and I stay busy..
 

JayTheCPA

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Focus on durability as there is not much in the way of kick-in-the pants gains without sacrificing durability.

Agree with the comment to not use marine injectors. From experience, they gained me nothing other than extra belching at start-up. OE injectors were noticeably more responsive to throttle inputs than the marines. Check with Leroy to see if he has a set of OE's. My vote is sell the marines to somebody whom thinks they are better than they really are.

Toward the parts list, consider a bypass filter. Or better yet a relocation kit with the dual filters.

And consider swapping out the Stanadyne FSD (it is a PMD when mounted to the IP) with a Flight Systems from Leroy. Got another subtle improvement in throttle response when I did this swap too.

When the time comes, a tune will play a huge role in the truck's overall behavior. And, the decision on turbo will make a difference in which tuner to work with.

Oh, and the IP . . . I developed an allergy to reman / rehab'd IP's. New or nothing. I know that some have had good results with reman IP's, but I did not.

If you can find a P-400, it is a tad more quiet than the other variants and supposedly a little more robust. But nothing is really going to make that motor very quiet aside from either going deaf, or a quality stereo system ;)
 

Potluckslammy

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You can still order brand new long block from GM and get a 3yr warranty, BUT if you or someone else opens it up to modify things it voids the warranty.

I just shipped a P400 crate motor that I tore apart and heavily modified and sent it back to him, he is on this forum and I'm sure he will pipe up once he gets it installed...



Well, I have backed up my R&D with facts for years, and no, I'm not going to revel all my findings due to others copying for no spent money in their own R&D..

I guess with you being new to the site it's just talk, I'm good with that, I know my services are out of reach of a lot of people, but I do have a lot of folks out their that know what works and I stay busy..
I was not aware such was still to be had from GM. That 3-year warranty is mighty attractive...and I will definitely weigh it as an option...but would rather upgrade to the Optimizer platform.
Please don't get me wrong with my comment about your website. To clarify my meaning, a bit of scepticism is healthy when faced with anything new, bright, and shiny...especially on the Interwebs! But any hesitancy on my part was put to rest after discovering your membership here at TTS, watching your active participation in the forums, and seeing the trust placed in you by the community. It's pretty damned awesome, in fact, that you and some of the other vendors take the time to join in the discussion, and actively help to sort out individual problems! It tells me that you do what you do not just to make a buck, but because you BELIEVE it's necessary and helpful...because you are a professional, but also still an enthusiast...you're one of US!
 

Potluckslammy

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Jay, I agree with everything you said. However, I believe long-term durability is to be had hand-in-hand with an increase in performance. Up to a point. The key is starting with a durable foundation...the Optimizer for my preference, and the P400 for those that can justify the cost. Then, choosy selection of quality parts, followed by accurate clearancing and careful assembly. Finally, insuring the investment with a Fuidampr, and robust cooling.
As for my own need and desire, it's not for a "Mountain Motor", as we used to call it back in my Harley days. But then, likely much like everyone else here, I'm one that just can't leave well enough alone when I know something can be made just a little bit better!
You're right, some type of upgraded filtration is an absolute must! I've also considered some kind of centrufugal filter. In fact, I learned Leroy offers an excellent kit that I'm considering. Everyone should check out his YouTube video!
You're probably right about the reman IP, too. I've always felt uneasy about it...bought it just because it was a "cheap" replacement. There was likely nothing wrong with the original, or it's replacement...at least until I boogered up the Encoder Ring while dicking around with the Optical Sensor! Anybody new a good, low mile core?!
Oh, and I like mine a little noisy! Well, the diesel rattle, and turbo whistle is music to my ears. Metal on metal grinding, and loud banging....not so much!
 

Twisted Steel Performance

Formerly: sctrailrider
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Most people don't do much investigating ( not directed towards anyone just a general observation ) they take info from various places from people who are just passing along something they read somewhere LOL .. never asking or most of the time looking for data to back anything up, if enough unknown people say something it must be true.... right... :banghead:

GM hasn't manufactured a 6.x in a very long time, but they still offer the factory replacement, ie the optimizer, GM could not ever order a P400 and wouldn't because it was never designed for public use.. The optimizer will be around a long time I think, but it is STILL the same week design with "said to have" better metal, to my knowledge that has never been tested, and they still crack just like the old motors did...
 

Will L.

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If you can get your hands on a p400- YES! The main girdle, the fractured rods, the pistons, the heads- all major improvements. If from us Engines- again I would tear it down. Still make some Improvements.

I did read from gep on the optimizers metallurgy to gm. It is higher chromium (and Nickel iirc).

And there was inside block water castings improvements made for the either march or april (have to look it up) gm 506 blocks to help cylinders 7&8 more which carried over to the Optimizer.
I am trying to find proof, but GEP nor Scat will confirm or deny what I think, and what a few high end long term machine shops I have taken them to believes- that GEP is not doing the crank. It seems Scat is doing the optimizers crank. Ive Recently put my optimizer crank next to a Scat. The scat crank owner and I only new which was which and because I had my balancer bolt and washer in mine- he was willing to “risk” the swapping if the machinist swapped them around trying to find the difference of quality.

But yes optimizers bottom end is still way out of balance like a gm. And the heavier rods and pistons compared to roughly 400cid sized ford/chevy/dodge gassers- the machinists always comment how heavy bob weight they have to run in balancing.

So if GM or optimizers- absolutely balance the bottom end, true the rods, etc. remember a better harmonic balancer helps- but it is for HARMONICS- not to fix an extra hunk of metal swinging around at 3500 rpm.
Out of balance beats them up, and when the balancer goes bad- out goes the mains.

On that same premise- main studs. You know it’s a weak point- why not help it where you can? Get the studs to the bottom of the hole, use all the thread that are there.
A 5 cap girdle is so obvious helpful in racing- cant be a bad idea here. Only no body sells one. There is the 3 cap one made that is basically angle iron. Can’t see it hurting any. But a existing cap/ 10 hole, vertical supporting girdle would obviously help. And require a custom oilpan.
Who knows, maybe soon some Alaska made cast iron mega girdles will be for sale. Innthe mean time donwhat you can to support the weak spots. Chryo the block for helping that strength. Just do ball all machine work first including ball honing, or it will take a LOT more time.

The best heads are hands down p400. Shy that the optimizers seem to hold up better than gm castings by a bit.

The chinese heads need to start out with a valve job clean up.

Everything benifits from chryo. Many parts benifit from coatings. No reason to not coat at least bearings. Combine chryo and coatings on entire engine if wallet allows- both proven tech that improve life.

Gapless rings help with oil consumption and longer before blowby, along with cleaner oil.

The new bosch (who i am currently mad at over glowplug) injectors still seem to be the best available. The German made are the best but out of production, never pop up for sale. (I have some nozzles listed now, but not for cash unless I find the new precups i want and my Germans wont be cheap). The India ones do good though, so don’t hesitate to buy them.
(Any injector I put in from now on will always be chryoed along with precups, rings, all cheaply shipped parts no matter what).

There are other places for improvements, but those all become more $ vs return you need to evaluate.

Btw, your upgraded radiator and the restnof the cooling stack- sending to TSP for coatings will greatly improve heat shedding. A constant % can never be set- but all the reading and questioning I done outside of TSP- looking at 3rd party testing and customer results from other approved applicators- all netted roughly 30% increases. Idk if he can legally say that, but as a customer I will. Only 1 customer reported as low as 25% I could find. Several as high as 35%. I know not engine, but you mentioned and obviously learned the importance of heat shedding for these puppies.
 

Jaryd

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