6.2L Dream Build

67_C-30 · Feb 28, 2013

Tplane37 said:
I haven't seen the exact post you referenced, but similar information is available in another thread on that forum that I have been reading.

http://www.dieselbombers.com/6-2l-6-5l-performance/68582-6-2-performance.html

The fuel mileage is another reason I am interested in the 6.2L. I am more interested in higher torque than higher horsepower, but obviously, increasing the output of one will increase the other as well. Some of the structural issues with the block (provided we are starting with a good block, meaning no cracks, etc.) can be improved by having the block cryogenically processed which will "correct" some of the molecular imperfections by equalizing their "layout" in the casting.

As for the crank, I have read that the crankshaft is a weak point, but mostly from a collateral damage perspective due to a spontaneously failing harmonic balancer and/or weak main caps. This leads to more questions, of course. The issues with the main caps can only be addressed so much without changing the block casting itself (such as with the P400 6500 block). But what about the crankshaft? Are their forged cranks available for the 6.2? Where can I go to find the specs on the main and rod journals? At one point, I had found a company that could custom grind just about any crank you could come up with, I remember having a discussion with them about a custom ground crank shaft for a high HP 4.3L GM V-6 back in 2004. The pricing wasn't to extreme, but it wasn't cheap either. I also know that I can get custom ground cranks for my Hudson and Terraplane straight 6's and straight 8's... this leads me to believe that the 6.2 should also have something out there to take care of a weak crank shaft.

Also, with the recomendations that the harmonic balancer on a 6.2/6.5 be changed religiously every 100k miles, one would presume that there is a performance upgrade for these as well. And thinking about my Hudsons, their blocks are balanced and blueprinted from the factory (and their blocks are actually a chrome-moly type variant)... how well would balancing and blueprinting the 6.2 work out for us? The article I posted above about the race engine implies that this was done (as well as other fairly extreme measures) and that the 6.2 connecting rods were used for strength reasons.

And I am still looking for the exact differences between the 6.5 and the 6.2 heads. I have read that putting the 6.5 heads on a 6.2 makes a screaming bandit... for a short while, until the EGT's get to high and that's all she wrote. But if the valves on the 6.2 are larger than the 6.5, all I can think of is that the intake/exhaust runners are different between them and/or the precombustion chambers are different. But which one is the cause of the massive gains from putting the 6.5 heads on the 6.2, and what can we do to keep this combination from grenading the engine shortly after the build?

Besides the slightly different injector angle, the biggest difference is the size of the ports in the precups. The 6.2 precups have small, round d-shaped ports and the 6.5 have wider, bigger o
blong shaped ports. The diamond precups used in 6.5 turbo engines will make more power than 6.2 precups, but at the expense of fuel economy.

The first is a 6.2 precup and the second is a 6.5 turbo head.

67_C-30 · Feb 28, 2013

As far as my dream build, I have just about everything for as close as I'll ever get to my dream build. I have a late model 6.5 Navistar enhanced block with the late model heads with diamond precups. I also have an open single plane intake from a early 90's N/A 6.5, and a 4911 6.5 turbo injection pump. I am going to build an 18 : 1 compression 6.5 with a DSG stud girdle kit, ARP head bolts, with a turned up 4911 IP, with a HX-35 Holset mounted on the Banks manifold and and the Banks pressure chamber mounted on the open single plane intake. Similiar builds have resulted in around 250 - 275 HP and 550 - 600 ft lbs of torque depending on boost and fuel rate. Living in the south, the 18 :1 build will be fine because its doesn't get cold to have adverse effects on starting.

I plan on building this engine for my M1009, but I have a lot of other projects in front of it. The 6.2 with the Banks turbo does really well now, so I'm in no real rush.

nattieleather · Mar 1, 2013

A little off topic, but somewhat relavant. Can one put 6.5 turbo heads on a 6.2 motor with out any modification to the 6.2 block? Jyst wondering.

wayne pick · Mar 1, 2013

Yup, they are interchangeable. Use the injector lines off the 6.5, they have slightly different bend to them. Use ARP head studs, do not re use the head bolts.

nattieleather · Mar 1, 2013

What are ARP studs? Is that a brand name or manufacturer?

wayne pick · Mar 1, 2013

Both, look um up at Jegs or Summit performance parts. it's really not a good idea to re use head bolts, they stretch. You can use stock replacement GM head bolts if the ARP studs are beyond your budget. The head studs are the better choice though.

Barrman · Mar 1, 2013

Here you go Joe:http://www.summitracing.com/search/...r/1985/engine-size/6-2l-379?keyword=arp studs

Tplane37 · Mar 1, 2013

These guys are absolutely correct. Reusing head bolts is a bad idea, they have a tenancy not to hold torque, plus you most likely have no idea how many times they have already been reused in a shade tree head job/gasket change in the past.

The ARP studs are a worth while investment. They hold their torque better, and don't stretch as easily under the added pressures of the increased boost from the turbos.

67_C-30 · Mar 1, 2013

Tplane37 said:
These guys are absolutely correct. Reusing head bolts is a bad idea, they have a tenancy not to hold torque, plus you most likely have no idea how many times they have already been reused in a shade tree head job/gasket change in the past.

The ARP studs are a worth while investment. They hold their torque better, and don't stretch as easily under the added pressures of the increased boost from the turbos.

ARP studs are better for sure, and best of all they are reuseable, but I have had a couple of turbo engines with new stock replacement bolts, and they hold up fine up, but they are "one use" bolts as well.

67_C-30 · Mar 1, 2013

nattieleather said:
A little off topic, but somewhat relavant. Can one put 6.5 turbo heads on a 6.2 motor with out any modification to the 6.2 block? Jyst wondering.

6.5 heads will wake up a stock N/A 6.2 because of the bigger precup ports, but you can hurt the engine when revving it high or working it really hard because without the boost of the turbo, the EGT's can go through the roof if it getting too much fuel. Its actually easier to melt down a N/A 6.2 than a turbo'd one.

3rdaavbn · Mar 1, 2013

I have a few CUCV cylinder heads that are NOS new old stock if interested.

Tplane37 · Mar 1, 2013

3rdaavbn said:
I have a few CUCV cylinder heads that are NOS new old stock if interested.

Could you share what casting numbers they have and what, if any, noticeable differences they have? Pictures of any differences would be helpful.

nattieleather · Mar 2, 2013

Thanks for the info on the ARP studs. And yes I know not to reuse head bolts.

3rdaavbn · Mar 3, 2013

one head casting shows 10137687 on one side of the top and 68975 on the other. and then on the lower end SRF.
The other 2 show 10137567, GH14 and 567. The only differance on the second two is that one has I251 and the other has 160I.
Is that at all helpful? I'll get some pictures today.

donalloy1 · Mar 3, 2013

I Have been told that GM shops can perform what is called Dynamic Tuning on 6.2 to optimise all available HP and Economy? Has anyone taken 6.2 J code in to GM for Tune?
Sure I would like a little more power in fully loaded long pull situations! Why not pursue via this angle first? I am not unhappy with existing power available though. Gets much better MPG than newer vehicles in stable and weighs 2000 #'s more.
This tread is outstanding! Look forward to applying what I have and will learn from material made availible here.

wayne pick · Mar 3, 2013

Hea Don, I searched "dynamic tuning" and got nada, I think you mean dynamic timing. I searched that and found a few pages on it. www.thedieselplace.com etc. As far as the dealership doing the work, I think i'd find the oldest mechanic in the place to do the work. The lap top kids would probably not even recognize one of these trucks as a GM product! LOL!

67_C-30 · Mar 3, 2013

wayne pick said:
Hea Don, I searched "dynamic tuning" and got nada, I think you mean dynamic timing. I searched that and found a few pages on it. www.thedieselplace.com etc. As far as the dealership doing the work, I think i'd find the oldest mechanic in the place to do the work. The lap top kids would probably not even recognize one of these trucks as a GM product! LOL!

I agree - the GM dealers around have no clue about how to work on anything that you plug a scanner into. The last time I went to the Chevrolet place for parts for my old '84 K10, the service manager (a 30 something year old genius) commenced to tell me how I ought to be looking into getting myself a new truck because 6.2's were "crap motors" and I was driving a "ticking time bomb". I laughed and informed him that the truck had 320K miles (at that time) and the valve covers had never been off of it. I told him that it got 23 mpg in town and 27 on the highway. I asked him straight up "Now, can you sell me a new fullsize truck on your lot with a guarantee that I'd get 320K on the engine and that it would get that kind of fuel mileage?" Of course, he drew a blank, and I just smiled said "Yeah, I didn't think so."

I sold that truck still running at 339K and they guy that bought it from still has it and I still see on the road from time to time...

Tplane37 · Mar 4, 2013

3rdaavbn said:
one head casting shows 10137687 on one side of the top and 68975 on the other. and then on the lower end SRF.
The other 2 show 10137567, GH14 and 567. The only differance on the second two is that one has I251 and the other has 160I.
Is that at all helpful? I'll get some pictures today.

Honestly, I don't know how helpful this is so far, but I can say it is a start. Another member mentioned we should build a database on the 6.2/6.5 engines, and that this database should include casting numbers and whatever information we could gather so that we can try to figure out the various combinations possible. It has been said that there are about 5 or so different casting numbers for the 6.2 and at least as many for the 6.5. There are also numerous injection pumps that will bolt up and "interchange."

The issue is inconsistency in matching parts and combinations... person "A" can take an IP from model year "X", the heads from model year "Y", and injectors from model year "Z" and end up with decent MPG's and increased power while being able to run alternative fuels as well. But person "B" can do the exact same thing, pulling the same parts from the same model year trucks and engines, but ends up with a combination that can't move the truck out of its own way and gets gallons per mile instead of miles per gallon, and has an engine that barely idles on pump diesel, let alone run dependably on alternative fuels.

The only logical explination is that component designs changed frequently and drastically from casting to casting, some times in the same model year. These changes are trackable through the casting numbers and symbols of the various parts, so we need a database of casting numbers/symbols so we can research what changes were made and when.

The best suggestion I can think of on cylinder heads at this point is to make sure you have matched heads. In other words, the same casting number/symbols on each bank. Small bock Chevies, Big blocks, and most every other GM cylinder head I have seen has a casting 'symbol' on the front and/or rear of the head. For example, double hump heads literally have two humps cast into either end. Some SBC heads have two triangles of equal height, others have one tall triangle next to one shorter triangle. If you put a double hump (2.02 intake valve and large runners) one one bank and a double triangle (1.94 intake valve, large runner... I think) on the other, you end up with performance problems. This applies on other GM heads as well, though I can't remember all the symbols. It is very likely that the diesels share this same tried and true identification scheme. Look and see if there are and symbols cast into the head near where the alternator mounts up.

350TacoZilla · Mar 4, 2013

I'm currently planning a 6.2 build and have looked up countless setups, personally I'm not doing a over the top no expense spared build but I will give you run down of what I think.

again my build will be using mainly stock off the shelf type parts, if money was no option get a machine shop to do billet steel block and heads and just spec the build to use largest valves,runners etc that would fit.

6.2 heads have larger valves but small pre-cups, you can get more power out of stock 6.5 heads then stock 6.2 heads but mpg suffers. I personally plan to spend alot of man hours porting and polishing my 6.2J code heads till nascar teams would be proud of the port job. I may try to find a better set of aftermarket valves and springs to fit but not playing around with sizes.

Delta cams regrind for towing/mpg instead of their coal cams lol

6.2 pistons are actually better design for mpg/power than 6.5 and I do not plan to over-bore motor so stock pistons will get balanced and 2 stage coating. Hightemp ceramic coating to the top and teflon coating on skirts. Carbon raptor will probably get the wrist pins and plan to setup floating pins with custom machined teflon buttons holding the pins in.

rods will be stock 6.2 rods taken to machine shop locally and heat treated,balanced,then shipped off to carbon raptor for coating.

crank will be either a scat cast crank or peninsular forged crank (either has to be machined to fit 6.2 block) depending on what I can afford at time. scat can be had for $300 and up pen is $1200 so probably scat. balanced ,smoothed and knife edged.

stud girdle that not only connects all the caps but also goes fully around the block to sandwich under oil pan.

ARP head,main,rod and pan studs.

Stans headers for 6.2

Either 6.5 turbo intake ported or sheetmetal intake, either will be machined to fit a eaton m90 supercharger

standard 6.5 serpentine belts,water pump etc

marine 40hp injectors.

marine DB2 pump turned 1/4 up

harland sharp roller rockers.

gear drive for timing.

m90 blower will be ported and possibly have the rotors and housing coated also.

swbradley1 · Mar 4, 2013

Not that I have much to add to this but I do live close to GEP. I looked it up and I drive by it all the time on I75 and have always wondered what they did in that building, now I know. I learned something new.

http://www.amgeneral.com/vehicles/gep/

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