Engine Rebuild Have-To's

[codyn]

With ported heads you would have seen less boost. Its easier to make more boost with stock heads.

yea i know because air flow better with ported heads. can you tell me how much boost it would be with ported heads and if you change the intercooler it will go down farther than that but how much more. but its all in setup and what kind of charger your running. which was not a reg gt 42.

 

[EDP]

yea i know because air flow better with ported heads. can you tell me how much boost it would be with ported heads and if you change the intercooler it will go down farther than that but how much more. but its all in setup and what kind of charger your running. which was not a reg gt 42.

I would guess you would probably drop down to about 45-50 psi. Dont get all wrapped up in boost numbers. Its the fianl boost eficency that makes the power I have seen time and time again a 60-70 psi twin setup out preform a 90 psi setup, same motor upgrades, similar size chargers. Also remember a dyno will never beat you at the track.

 

[codyn]

I would guess you would probably drop down to about 45-50 psi. Dont get all wrapped up in boost numbers. Its the fianl boost eficency that makes the power I have seen time and time again a 60-70 psi twin setup out preform a 90 psi setup, same motor upgrades, similar size chargers. Also remember a dyno will never beat you at the track.

yea by track times it was around 830 hp im not wrapped up in boost numbers. i was making more power at the higher boost level on the track then what it was making on the dyno. it was the first tune i tried with the new injectors which was torque management. it was acting up on the line which would not let it go over 2000 rpm so it was not even tuned in . but im not in here for a pissing match about twins verses singles or you think i did a no brainer idea trying something different and it worked. everything came out to spec and on tear down insepection everything looked great. so lets get this back on topic.

 

[JOHNBOY]

Any of you guys think that having the rotating assembly balanced is a MUST have when doing a build? Since aftermarket rods and pistons will more than likely be used.

And John, somewhere didn't you say that when using head studs the block "moves" .004 of a inch?? And that's why you are saying that torque plate honing is a must?

I think balancing is needed. Most aftermarket parts are lighter which means weight needs to be removed from the crank. That is really not that expensive. Balancing gets pricey when you need to add weight to the crank.

The movement I talked about is the bore getting squeezed smaller. The extra force from the stronger studs and increased torque not only pulls the head down tighter it forces the threads in the block outward. This moves the bore inward. If your bore had .006 piston clearence in free state it could very likely have as little as .002 afterward as measured with a bore gage. When measured between the studs. The only way to correct this is to bore and hone with a torque plate.

 

[jimbar99]

Torque Plate

In the St. Louis area, AMT Racing Engines has a Duramax torque plate. According to their website,

"You can't afford not to torque plate hone your block. It produces the best ring seal possible and therefore makes more power. We installed studs in this block which required drilling and tapping for the larger diameter studs. They distort the block differently than the factory bolts, so torque plate honing is a must. Note the spacers used to mimic the amount of thread engagement when the head is installed and therefore recreate the stresses as closely as possible. If you hone your Duramax diesel block without a torque plate, you are definitely missing some power gains."

These guys do a lot of performance engine machine work and have a great reputation as meticulous machinists. They are a good resource if you are in the area and need top notch machine work done, whether line hone, bore and torque plate hone, install studs, head work, etc.

Johnboy is exactly right that balancing is needed. The stock stuff is not even close to perfectly balanced (manufacturing tolerances for mass production), so any performance upgrade is an opportunity to correct the situation. You might be surprised how much better a balanced motor runs. It's not something you should skip. Motors that are out of balance will eventually tear themselves apart, even though it might seem that they smooth out above a certain RPM.

BTW the AMT website is http://www.amtracingengines.com