Thinking of best way to approach new engine install. I see the P400 is rated 250HP and 550t, does that mean thats what it puts out in stock trim or what? Can it take more boost? What are the numbers on the optimizer? Can you expect more longevity with the P400 VS Optimizer under same conditions? If you have to spend 1,000 more on an Optimizer to get it to put out what a P400 does out of the crate, I'm thinking the P400 is the better deal.
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P400 questions
- Thread starter Hill Top
- Start date
Will L.
Well-Known Member
The p400 is the pinnacle. The power rating is what it is set up mass production for. The more power you pull from it, the sooner it should wear out theoretically like any engine.
The power capability is going to be better on the p400. Everything about the engine is simple built stronger.
Read the thread on what Leroy did to his. That is what I would do, except I would have to push a lot more power with 311 injectors, big azz IP, and if I could fit the extra one, compound turbos.
But I get carried away when spending $, and thats part of why I am so broke now. Haha.
Seriously I own an optimizer, and wish for the p400. No contest which is better. It will absolutely outlast any 6.5 in same power levels.
The power capability is going to be better on the p400. Everything about the engine is simple built stronger.
Read the thread on what Leroy did to his. That is what I would do, except I would have to push a lot more power with 311 injectors, big azz IP, and if I could fit the extra one, compound turbos.
But I get carried away when spending $, and thats part of why I am so broke now. Haha.
Seriously I own an optimizer, and wish for the p400. No contest which is better. It will absolutely outlast any 6.5 in same power levels.
JayTheCPA
Well-Known Member
P-400 is a nice motor. It is notably a few Db more quiet than the 506 that I had.
Power will depend on aftermarket modifications and tune. So, if the goal is to simply transfer OE components on to the P-400, expect OE power. Toward the potential of 250 / 500, even the military and Banks cannot get all the stated rating out of the motor although better than OE is definitely possible. The last dyno I did came in around 245 / 394 where the notable modifications were marine injectors, ATT (turbo), exhaust, and a tune.
While the P-400 will drop-in, the extra 3" girdle will force purchase of a custom oil pan, so this will increase the price differential from an Optimizer. If the tranny is automatic, plan on either modifying the lower cover or leaving it off.
Toward the overall project, do not recommend simply transferring OE cooling parts as it seems that the goal is to get more power out of the motor which in turn is more heat to shed under load. Plan on making sure the cooling stack is in excellent shape if the intent is to tow.
Whether the final decision is the Optimizer or P-400, consider adding the gap-less rings. I was talked out of them by my seller and am now wishing that I had them installed just from the perspective of minimizing soot in the oil.
Regarding the question about more boost. Am not personally sold that having more boost is desirable. Having a system that breathes well and burns the fuel without smokey exhaust is the better approach to the question. Put another way, the dyno numbers that I got were at a measly ~12 psi.
Power will depend on aftermarket modifications and tune. So, if the goal is to simply transfer OE components on to the P-400, expect OE power. Toward the potential of 250 / 500, even the military and Banks cannot get all the stated rating out of the motor although better than OE is definitely possible. The last dyno I did came in around 245 / 394 where the notable modifications were marine injectors, ATT (turbo), exhaust, and a tune.
While the P-400 will drop-in, the extra 3" girdle will force purchase of a custom oil pan, so this will increase the price differential from an Optimizer. If the tranny is automatic, plan on either modifying the lower cover or leaving it off.
Toward the overall project, do not recommend simply transferring OE cooling parts as it seems that the goal is to get more power out of the motor which in turn is more heat to shed under load. Plan on making sure the cooling stack is in excellent shape if the intent is to tow.
Whether the final decision is the Optimizer or P-400, consider adding the gap-less rings. I was talked out of them by my seller and am now wishing that I had them installed just from the perspective of minimizing soot in the oil.
Regarding the question about more boost. Am not personally sold that having more boost is desirable. Having a system that breathes well and burns the fuel without smokey exhaust is the better approach to the question. Put another way, the dyno numbers that I got were at a measly ~12 psi.
JayTheCPA
Well-Known Member
Yes, Leroy discovered that even 2WD needed a custom pan for the P-400.
Rebuilding? Well, as far as professional engine re-builders are concerned the GM cast stuff is scrap metal. The blocks crack to death making it hard to find a good block and two damn good heads to work with in a pile of used engines. Literally the 6.2 and 6.5 is a throwaway engine. (A 6.5 is just a punched out 6.2. Main difference is in the heads for injector angle and precups. 599 blocks only have the cylinder size different and best I can tell some GM 599 crate engines did not have the 6.2 or 6.5 cast in the block as they could be 6.2 or 6.5's.)
A good plan is surplus military used and buy from an outfit that test runs their engines. Best if you can hear your engine run on a stand. Then freshen it up with rings etc.
This said the Optimizers and P400's are rebuildable as they changed the design to fix the crack prone areas. Of course you need one that isn't full of dessert sand...
Some of us go through 6.5 and 6.2 GM cast engines and get one running frugally. For example you can get a test run low 30K mile NA 6.2 military surplus for $1500.00. Starter, ARP head studs, and Misc krap has you up and running for $2500.00. I would recommend an additional expense of 6.5 heads with turbo precups for the ATT.
Gapless rings I have oil samples posted around here of "0" soot where I can read the marks on the dipstick under the oil at 2000 miles. It takes 4000 miles to hide the marks now the engine has 30K+ on the gapless rings and I run it more than 3K miles in a year.
At the end of the day what's it worth to you for the best there is to reduce the risk you have to pull the engine again? There are no guarantees as even the 1/2 million TBO industrial Cummins I have that is known for 1 million miles has been out 2x and replaced the 3rd time in under 120K. I expect the replacement to last longer than a 6.5 unless SHTF. (Literally as elk $hit has, in fact, hit one of our fans before. Drove the waterpump shaft into the timing cover and really really messed up the metal fan.)
A good plan is surplus military used and buy from an outfit that test runs their engines. Best if you can hear your engine run on a stand. Then freshen it up with rings etc.
This said the Optimizers and P400's are rebuildable as they changed the design to fix the crack prone areas. Of course you need one that isn't full of dessert sand...
Some of us go through 6.5 and 6.2 GM cast engines and get one running frugally. For example you can get a test run low 30K mile NA 6.2 military surplus for $1500.00. Starter, ARP head studs, and Misc krap has you up and running for $2500.00. I would recommend an additional expense of 6.5 heads with turbo precups for the ATT.
Gapless rings I have oil samples posted around here of "0" soot where I can read the marks on the dipstick under the oil at 2000 miles. It takes 4000 miles to hide the marks now the engine has 30K+ on the gapless rings and I run it more than 3K miles in a year.
At the end of the day what's it worth to you for the best there is to reduce the risk you have to pull the engine again? There are no guarantees as even the 1/2 million TBO industrial Cummins I have that is known for 1 million miles has been out 2x and replaced the 3rd time in under 120K. I expect the replacement to last longer than a 6.5 unless SHTF. (Literally as elk $hit has, in fact, hit one of our fans before. Drove the waterpump shaft into the timing cover and really really messed up the metal fan.)
Nessmuk
Well-Known Member
I know a better, marine injection pump will let you add more boost and per a guy here's build, make some awesome numbers.
This is my truck:
86 CUCV, 6.5 Navistar, ARP Studs top and bottom, HX40WII Turbo, 3 into 4 into 5 inch exhaust, Exhaust manifolds and ports ground to match, 14 ply 9-16-36 bias ply tires, H.O. Water pump, Hi CFM fan, 4 cored industrial radiator, Remote oil cooler, Dual alts, 4L80E transmission, Twin sticked NP205, 2 transmission coolers, 4010 u- joints, Water methanol injection, Rebuilt injection pump and hi pop injectors, Steering cooler in radiator, Detroit locker, Dual tanks, fuel pumps and filters, Oil, Trans, Water temp gauges, Pyro, Tach, Boost gauges, Oil press, Fuel press, Volt gauges, Trans press gauge.
Will L.
Well-Known Member
Nessmuk
Well-Known Member
It's at the trans shop.
Anyone that says ya can rebuild one cheaper than purchasing a new motor is not truly rebuilding it, cheeping out on most things and cutting corners, it's that simple.. Yep you can throw some parts at it and hone the cly and such, a true rebuild will be costly, line honing, boring, pistons etc.... and you will still have a crack prone block that sucked before you so called rebuilt it and it still will...
If you expect or want it to hold up under more stress of higher boost & fuel you will spend the money once and buy a new motor... my 2cents for what it's worth ... And yes, a p400 is worth the cost, it is in NO WAY the same motor, I have shown some of the differences that can't be seen from the outside and still haven't shown all I have found different.
Take whoever's word you wish but be advised most haven't ever cut up a set of heads much less a new 2000$ set to find the differences... I have and have pics here of SOME differences...
If you expect or want it to hold up under more stress of higher boost & fuel you will spend the money once and buy a new motor... my 2cents for what it's worth ... And yes, a p400 is worth the cost, it is in NO WAY the same motor, I have shown some of the differences that can't be seen from the outside and still haven't shown all I have found different.
Take whoever's word you wish but be advised most haven't ever cut up a set of heads much less a new 2000$ set to find the differences... I have and have pics here of SOME differences...
Nessmuk
Well-Known Member
The 400 has a lot more steel. It is a block that happens to use most of the 6.5 gm\amg parts.
The AMG Navistar block is able handle the horse power and torque you'll likely ever make. If it was made in the GM days I'd pass.
The AMG Navistar block is able handle the horse power and torque you'll likely ever make. If it was made in the GM days I'd pass.
They ONLY use the parts on the outside of the motor, nothing other than the pushrods & rockers inside...
And the timing set... other than that nothing will interchange from p400 to anything else...
Will L.
Well-Known Member
You could fit the cam, but it is not the same specs or material. They juiced it up too.
Its an absolute no brainer, if you can swing the P400 then thats your choice.
Unfortunately the P400 has not been available for a few months though (I could have sold 20. No exaggeration). The good news is they are supposed to be back mid to late March.
Start here and follow my build.
Unfortunately the P400 has not been available for a few months though (I could have sold 20. No exaggeration). The good news is they are supposed to be back mid to late March.
Start here and follow my build.