6.4 internal limits?

[Nic]

Besides pistons, what would yall consider the "limit" for HP when building these? I have a buddy fixing to pick up a regular cab and wants to throw bigger turbos on it and this guy isnt one thats "light" on the throttle....Drive it like you stole it kind of fellow.

 

[dmkolb]

If he's going to spend all this money and have the engine apart anyway there is no reason not to go with aftermarket rods just for the extra insurance. He's gonna be pissed if he builds the engine and by some fluke a rod fails and destroys the engine because he stayed with stock rods. Plus it should be able to take anything he throws at it once he has the short blocked buffed up.

 

[6.4strokin]

6.4s stock bottom end is pretty stout. If he has the coin he can get better rods but There's 800 + hp on stock bottom ends.


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[Morgan@Midwest Diesel & Auto]

Not true, I've seen a lot of bent rods in just "tuner" trucks. Lots.....

 

[SDS97_7.3]

Not true, I've seen a lot of bent rods in just "tuner" trucks. Lots.....

Me LOL but mine ended up being a Jasper reman

 

[B585Ford]

IMHO it is a little more complicated than a HP #. Turbo set up and fueling down low are very important. It seems to me singles can make a lot more HP "safely" cause it doesn't have low RPM torque. Valvetrain will also factor in depending on how fast he plans to spin the engine. I don't work as a mechanic so people like Morgan and other shop owners see a lot more than me, but I can't recall ever seeing the bottom end fail in a non-reman engine that wasn't over-revved, floated a valve from high EBP, or the piston let lose in 750 HP or under application. Do they exist...sure, but in most applications, I would feel safe up 750. In the end, especially in high HP applications, ch#t eventually fails and the more it is abused, the sooner it usually fails.

 

[Nic]

Ok Ill let him know. Are we talking connecting rods or push rods?

 

[B585Ford]

Ok Ill let him know. Are we talking connecting rods or push rods?

Connecting

 

[Nic]

Well hell, if you go in to do connecting rods, one might as well do pistons? :shrug: All the fuss I hear about them being crack prone all the time has me watching the EGT like a hawk trying not to let them over 1100...

 

[B585Ford]

Well hell, if you go in to do connecting rods, one might as well do pistons? :shrug: All the fuss I hear about them being crack prone all the time has me watching the EGT like a hawk trying not to let them over 1100...

Definitely. The rods are much tougher than the pistons

 

[Stroked777]

Well hell, if you go in to do connecting rods, one might as well do pistons? :shrug: All the fuss I hear about them being crack prone all the time has me watching the EGT like a hawk trying not to let them over 1100...

I have a stock motor aside from a cam and I don't worry about egts. I maxed my mini max out at 1871(or somewhere around there) and after the run it still took a few seconds before it read anything lower than that, and my pistons are fine. I think a lot of cracked pistons are due to casting flaws. On a thread there was a cross section of a cracked piston and there was a huge air pocket close to the bowl which lead it to crack

 

[RSK]

I have a stock motor aside from a cam and I don't worry about egts. I maxed my mini max out at 1871(or somewhere around there) and after the run it still took a few seconds before it read anything lower than that, and my pistons are fine. I think a lot of cracked pistons are due to casting flaws. On a thread there was a cross section of a cracked piston and there was a huge air pocket close to the bowl which lead it to crack

no way to tell which truck has pistons that are gonna crack or not though...personally I just wanna do turbo's/ head studs, egr delete push rods and valve springs for now and stay stock fuel until next summer and do the trans then too, but if I delete the egr and do turbo's then my pistons crack in the winter or fall, I'm not gonna be happy. especially because I already had the cab up and it would have only been 3000 with lifting the cab, pulling the motor apart and changing pistons and studding the heads and doing the egr delete and changing the up pipes to hd ones all at once...so its like a ticking time bomb.

 

[Stroked777]

If I had the money at the time I would have dug deeper in my motor. I'll run it til something goes wrong

 

[B585Ford]

Pistons scare me cause they are so hit or miss but I am in the same boat....didn't have the funds for this round of upgrades so hoping they will hold up for about another 20k. Back to the original question, my goal is to get up to about 750 RWHP with compound turbos and I am not planning on replacing the connecting rods.

 

[Super08Duty]

When buying a 6.4, it's best to start looking for a spare motor. Pistons and rockers suck on these motors. If I were him, I'd put a built short block in it and feel much better. Just because these motors can handle a lot of power doesn't mean they'll last long.

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[dmkolb]

I will say I have a bent rod that says mine didn't like 560 RWHP. Still got the bent rod. I think your just asking for trouble if you want to make reliable 750 RWHP not doing rods. Why would you spend all that money and skimp on such an important part that if it does bend could easily destroy your engine and then your out everything you just did. That just doesn't make any sense to me. This is coming from a guy who has bent a rod making well under what you want to make. I ended up going with R&R Billet rods purchased from Morgan at Midwest Diesel and Auto. I don't worry about the rods anymore.

I have heard what causes a lot of pistons to crack is the lip on the piston. Morgan has pistons that are delipped, coated, valve reliefs, and anything else you can think of that is going to really lessen the chance of a piston failure.

 

[drunk on diesel]

details on the setup? I've seen bent rods on stock trucks, and I've had my poor F350 service truck at 10,000lbs every day at 570rwhp for the past 4yrs.

just curious

 

[Morgan@Midwest Diesel & Auto]

Lots of variables. Stock turbos and high cylinder pressure, and the inconsistency in stock pmr 6.4 rods. It comes down to what your willing to risk and what your budget is. Anytime you plan on making bigger power you better be willing to take the risk.

 

[B585Ford]

I will say I have a bent rod that says mine didn't like 560 RWHP. Still got the bent rod. I think your just asking for trouble if you want to make reliable 750 RWHP not doing rods. Why would you spend all that money and skimp on such an important part that if it does bend could easily destroy your engine and then your out everything you just did. That just doesn't make any sense to me. This is coming from a guy who has bent a rod making well under what you want to make. I ended up going with R&R Billet rods purchased from Morgan at Midwest Diesel and Auto. I don't worry about the rods anymore.

I have heard what causes a lot of pistons to crack is the lip on the piston. Morgan has pistons that are delipped, coated, valve reliefs, and anything else you can think of that is going to really lessen the chance of a piston failure.

I plan to get my pistons from Morgan and that is one of the reasons I feel I can get away with stock rods. As Drunk said, what was your setup and most importantly, do you know what your EBP was you bent a rod? I am sure the manufacturing could be a factor, but from what I have seen, the bent rods on a relatively stock setup can usually be attributed to a piston failure, an over-rev, or excessive EBP causing a valve to float. IMO a lot of guys running tuner only mods don't realize how high their EBPs are getting. I am already gated to help with that issue. Also, just like with the 7.3 PMRs, you can get them to live at a pretty high HP level if you pull a little fuel down low. Who knows, maybe I will hit the lottery and do everything, but with my budget, I doubt that rods will be changed until I need a complete new engine. I realize I will be taking some risk, but anything over stock is adding risk. Like Morgan said, it just depends on how much risk you are willing to take. Finally my truck will never be a competition truck, just something I tow with and have fun on the street with.

 

[drunk on diesel]

good point, I always ran a low LBF setting on my canned H&S tunes, and Matt is very tight on LBF.

I can see how someone running a low shift/lock shift schedule with a lot of LBF could definitely be taxing the rods down low