I asked on nloc, but wanted too here also.

I was just wondering because I have the KB now, and it sure would be nice to run 18-20#'s with it. I know as soon as I did I would definately put a window in my block. I just wanted to see how many people have done it, and a ballpark cost. Still haven't decided if I would do it myself or take it to a shop. It has to be considerably cheaper than a whole new block, but I wasn't sure how much more power it could handle.

Any opinions are appreciated.
Thanks
Shane

 

Thought it was said that the assy. should be balanced if your going to the trouble.

 

I would like to know this as well. Has anyone gone this route, and what were the details and pricetag?

 

I get this question alot. I feel that its more benificial to rebuild the whole bottom end then to just fix the "weak point." The rods from the factory arnt the greatest so replacing them is the way to go. Spending the amount of money that you will replacing the rods you are better off with the whole bottom done. If you fix the weakpoint then theres more than likely going to be another (pistons, rings, etc..). We carry full bottom end kits and have them in stock today.


My final answer would have to be rebuild the whole bottom end and run as much boost as you can through that sucker.



JimIII

 

So you could rebuild the whole bottom end for around $2000.00. That sure sounds better than $10,000 For a Longblock if I were to blow up my stocker. What ballpark HP ceiling are you looking at running safely on a built bottom end?

 

I agree $2,000 or $10,000 not hard to figure out. The Manley bottom end that we use is good for 900 HP. I really feel its the way to go.

JimIII

 

there's so much more than just replacing the rods. If you are gonna go through all that, do it right. Just replacing the rods doesnt' mean your golden. Depending on the rod......they are rated for x amount of horsepower.

If it were me, I agree with Jim, do the whole bottom end. Don't forget , your probably talking a 50/50 failure rate on these engines of rods/lower end.......and valve train/head problems. If you run lean and burn up a valve which toasts you piston........isn't anything a built lower end is going to prevent.

 

so your bottom end rebuild kit is $2000? What comes in the kit?

 

As far as the 50% that toast a Piston, you are correct a built bottom end isnt going to help prevent that, a tuner you have a relationship and trust will prevent that. Now lets speak about the 50% that vent there block, it is always rod failure. The Pistons on these motors are very good and well designed. Back in the day people were actually building 4.6 Cobra and GT race blocks with them. The Pistons were a cheaper alternative to JE/Ross and they never failed besides being burned due to a poor tune. Ive looked into the idea of just replacing the rods and rebalancing the assembly but have been to lazy. The thing that backs my opinion is who here has seen a Rod Pin rip out of a piston ? Who has seen a piston skirt break ? I personally havent and even if it does break, 50% of the cost is worth the risk in my opinion.

 

Connecting rods don't just jump off the crankshaft because your making lots of power.

It is detonation and high RPM that will cause failure.

I agree that it is a safe tune that keep the engines alive and well.

 

While you are part correct, some rods do fail due to stress brought on by more power than designed to handle. Stock rods look like a pencil compared to a forged set of rods. Like comparing a reg pencil to a husky pencil you used in kindergarden

 

the manley's are nice, but i went with the modmax rods (same manufacturer as manley and eagle esp) because they came with the better arp 2000 rod cap bolts

 

have any of you done this rebuld yourselves?

 

5.4 No, 4.6 Yes same difference.

 

how big of a project was it?