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To those running "larger" injectors on stock forged rods

7K views 54 replies 35 participants last post by  chvyrkr81 
#1 ·
Something has been bouncing around my head the past month or 2. I thought I would throw this out to the masses since no one can ever agree on any "1 said thing".

We all are aware of the dangers of PMRs & bigger injectors. But what about forged rods, where is the invisible line drawn for a "safe" limit? Let's assume we are going to take a 99 or a 00 SD in good working order with forged rods. Now some will tell you forged rods will still blow up with anything much over a 175cc injector. Other's will tell you that you will be safe to run up to say a 250cc hybrid with 200% nozzles & a 70something mm turbo & be safe. Now assume we live tune the truck (insert tuner of your choise here no pissing matches) & get it dialed in. We will call "said" setup around 550hp+ how many of you will still have faith in your setup & not worry about blowing the bottom end of the engine all over the pavement. Now flip side how many of you will cross your fingers & pray that everything holds together.

Pretty much I thought this thread would be good to show who has had good luck & bad luck with a stock forged rods & a stock bottom end. No pissing matches needed in here just facts on setups that work & didn't work.
 
#2 ·
Cracked my block with the mods in my sig below. 1k on my new engine and its always in the back of my head if this one is gonna blow when I get on it. Getting live tuned next weekend, try and make the tunes safe as possible.
 
#3 ·
I popped 2 forged engines with stage 2 injectors. They both had a modded H2E turbo. Both were DP tuned. The 2nd engine was live tuned by Jody. I don't know where the safe limit is because I thought I was playing it safe.-Especially with the $450 live tune. I asked for tunes with 'safe' timing and nothing crazy, just reliable. Oh well, u gotta pay to play right?
 
#4 ·
Mine has held up fine for a while with my new setup...almost 10 months and 10,000 miles. Theres about 60 passes down the drag strip and maybe 5 hooks on the sled. I cross my fingers and knock on wood.....you never know. But so far so good.

355cc hybrids....gen3...s475 turbo.....etc....etc
 
#5 ·
IMO there are too many variables you have to consider. I don't think anyone can draw a line on what is safe and what isn't. Although thanks to those who have pushed the bar, we can estimate what will most likely hurt a motor.

Cracked my block with the mods in my sig below. 1k on my new engine and its always in the back of my head if this one is gonna blow when I get on it. Pray everyday I drive it.:( Getting live tuned next weekend, try and make the tunes safe as possible.
Perfect example, we have very similar setups and I have not cracked my block or broke anything, although I had mysterious water in oil problem that has fixed itself somehow.
 
#12 ·
Was hoss's motor still running when he pulled it out to install the built one? I know he had ALOT of passes down the track & alot of street miles with 3 stages of nitrious.
 
#7 ·
Yup, very hard to put a number on it. Everybody says Forged rods will hold x-amount of HP, what about everything else in the engine. Take mine for example. My #8 piston let loose taking out 2 rods and the block.

You never know when something may let loose and you have no control over it......If it's gonna blow, it's gonna blow.
 
#9 ·
Yup, very hard to put a number on it. Everybody says Forged rods will hold x-amount of HP, what about everything else in the engine. Take mine for example. My #8 piston let loose taking out 2 rods and the block.

You never know when something may let loose and you have no control over it......If it's gonna blow, it's gonna blow.
Kenny, You have to agree, your's let go from excessive EGTs and a cracked piston across the wrist pin. I can't blame that on the rods :doh:. I think there was some operator concerns going on there LOL. Not too often you get up pipes looking like pretzels from normal driving :poke:


:D
 
#13 ·
I split the block at less than 400 hp ! I have 2 spare blocks to play with bring it on powah gods lets do this. LOL I always have the thought in the back oh my mind is this SOB going to blow or go ? I built a fresh motor put it in the truck and drove it 35 miles it sat till I got back to it.I went back home got the thing legal and drove it 400 miles on a wing and a prayer. Yeah I have less than 600 miles on and the other day a Chummins rolled up on me ,As the foot went to the floor I was thinking chit if it blows then what. But when I put 3 lengths on this dodge all that went out the window. :D
Alls I want is a reliable 450-475 hp . I am getting tunes soon from TDP ! Then a preist is going to bless it for me :doh:
 
#15 ·
i am not too worried about 650 on stock rods. mine blew yesterday but pretty sure the rods were not the cause.
 
#18 ·
I've never owned, ridden, or driven a 7.3 with any more HP than mine, so I have no real world experience, but from what I've gathered, I would be comfortable at 550rwhp.

I think the fact of the matter is clean reliable power. Not being overfueled, or running your injectors with insufficient hpo.

I think the secret of it all would be having only the best components. Not just good tooning, but well balanced injectors, a good oil system, as well as sufficient air. Also, high EGT's and CP are what I think I'm gonna try to stay farthest from when I start putting my components together.
 
#25 ·
Yup. Driver is probly 90% of it. I could blow one up with 140cc and my driving. Well , that and a bottle.:D

I got a few buddies who could run a 800 hp capable setup assuming it was achievable, and be fine. Cause they never stand on it.

I drive mine like I hate it daily. Like every day. Not a trailer queen, not a show truck. Its a true daily driver, tow rig ,drag race, sledpull , firewood hauling truck. I would think thats a big part of it.
And for those who think that a "worn out stock bottom end motor" is a good reason why it blew, consider this.
Mine cracked the block at 180,000 miles +/- (cant remember for sure)
When I tore it down, it looked like a brand new motor inside. Hone marks in the cyl. bearings looked new, everything lokked like it was right off the assy line. Except the cracked block.
Miles means nothing.
Maintainence maybe, miles no.

Misuse, and abuse, along with tuning on the edge is a bad combo.
My buddy wants mileage, and big power, all in one. I tell them get a tune for mileage that has maybe 250 rwhp. Another tune for the hp that has less timing and makes good power. Not both at the same time.
I'm not a tuner on these things, so I cant pretend to know whats all involved, but I can tell ya I have looked at many , many cyl pressure traces, and seen detonation, pre-ignition, dead cyliders, and all .
There is a fine line between making hp with low cyl temps, and good fuel rates. More hp usually means higher cyl temps, and higher fuel rates.
Want more mpg? More timing, lower cyl temps, less smoke, more chance of peak pressures spiking above a safe level.

Lots of stuff to think about.
Is it worth it?
Hmmmmmmmmm......
 
#26 ·
Yeah mine split at 220k and yeah it looked good inside considering where it had been and the knuckle head that had been maintaining it. I am hoping that reducing the compression and a good tune will help keep it alive alittle longer. I will add studs, and convert it to s/d stuff and a gt38r when cash allows.
I want a reliable power level that is fun to drive.
 
#27 ·
I am probably in the 550 tp 650 range somewhere with my setup and not worried about the rods. Jonathan finished up the live tuneing on it this weekend and we had a sensor installed to check cylinder pressure while doing it, so I know first hand what is going on in the cylinder with my tunes. (weather I understand it or not:doh:)
On the other hand I cant say that I will be overly supprized if it dose blow up, at this leval any little thing can cause the end............. I do have a spare engine laying in the garage, but have no intent on useing it for a year or two.
it is just a risk you have to be willing to take.
 
#33 ·
My combo is pretty much the same as pontiac cross and powersmokers and i have a couple thousand street miles and only a few WOT pulls on the street on it. Zero track passes at this point, i want to make sure its it tip top shape before i go beating the hell out of it. I am having it live tuned by jonathan next weekend so hopefully that will ease some of my worrying about the bottom end.
 
#34 ·
my truck is modded as said in the sig.. i flog the living #### out of it everyday and it hasnt blown the bottom out of it yet.. granted i have broke just about every other part on the truck but the bottom end is still hanging on... i do however cross my fingers every time i drive it... but i have faith that my tunes shouldnt blow it
 
#38 ·
I just popped a headgasket at 4xx hp. It was due to the higher cyl. pressure in the #1 Cyl!!!!!!! replaced rod for safeness though.
 
#40 ·
Anything over 400hp... is a crap shoot.

Mine blew and never dynoed over 470hp...
 
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