Short Block Machine work ?

[spadepro22]

Would be the better to machine a 7-bolt crank to fit a 6-bolt rod, or switch to a 6-bolt and do the work needed to make the pistons fit the rods?

The reason I'm asking is I just put in a new 7-bolt flywheel and need to know which is cheaper. Swapping to the 6, buy another new flywheel and do the combo? Or do the machining to make the combo work on the 7?

 

[pauleyman]

Why do you want 6 bolt rods? If you're making that much power you should be considering different pistons, at which time you could get new rods etc. The goals of the car should determine what parts you buy, not which is cheaper. Flywheel is cheap. I wouldn't machine the rods to fit the seven bolt crank. Not even sure you can. I would get appropriate rods if that is what you need.

You might ponder this.
http://www.dsmtuners.com/forums/newbie-forum/421705-project-management-building-dsm.html

 

[spadepro22]

Why do you want 6 bolt rods? If you're making that much power you should be considering different pistons, at which time you could get new rods etc. The goals of the car should determine what parts you buy, not which is cheaper. Flywheel is cheap. I wouldn't machine the rods to fit the seven bolt crank. Not even sure you can. I would get appropriate rods if that is what you need.

You might ponder this.
http://www.dsmtuners.com/forums/newbie-forum/421705-project-management-building-dsm.html

I'm looking for hp in the 350-400 range and the 6 bolt rods are a upgrade from my 1g 7's. Well the crank might need the machining work done, sorry about that, I edited the post

 

[herms99gst]

Keep the7 bolt and just swap out the rod bolts for arp's.

 

[spadepro22]

And not change the rods/pistons? The pistons will give a higher comp. ratio for more hp. It's a 1g 7.

 

[pauleyman]

You dont' need to swap anything. If you want new pistons 2g pistons will fit on 1g 7 bold rods just fine.
This is why I asked the goals of the car.In my opinion you don't anything. Not even arp rod bolts. Bolt on and proper tuning will put you there. Actually there are no 1g and 2g rods, they are the same, hence the reason either piston fits. 7 bolt that is.

 

[spadepro22]

You dont' need to swap anything. If you want new pistons 2g pistons will fit on 1g 7 bold rods just fine.
This is why I asked the goals of the car.In my opinion you don't anything. Not even arp rod bolts. Bolt on and proper tuning will put you there. Actually there are no 1g and 2g rods, they are the same, hence the reason either piston fits. 7 bolt that is.

http://www.dsmtuners.com/forums/new...lved-how-can-you-tell-between-2g-1g-rods.html

The 1g rods are bigger and said to be stronger. What do you mean they are the same?

 

[2slow4now]

What Pauly was saying is a 7 bolt rod is a 7 bolt rod. It doesn't matter if its a 1g or 2g if its a 7 bolt its a 7 bolt.
You are correct the 6 bolt rods are known to be stronger but a 7 bolt should be fine at a 400hp level.

 

[spadepro22]

What Pauly was saying is a 7 bolt rod is a 7 bolt rod. It doesn't matter if its a 1g or 2g if its a 7 bolt its a 7 bolt.
You are correct the 6 bolt rods are known to be stronger but a 7 bolt should be fine at a 400hp level.

Got you. 400 on dd? I understand now that the 7 bolt rod will be good, but im also asking if its worth the machine to do the combo on the 7 to have extra security? Or do the combo on the 6 and get another flywheel.

 

[gsxtreme1987]

You honestly don't need to do anything to the block if your goal is 350-400.

Proper tuning and your motor will be healthy.

 

[2slow4now]

Your gonna have to decide 6 or 7 on your own. What your willing to spend. Are you comfortable with a 7 bolt or are you paranoid it will walk? Do you trust your machinist to customize rods, pistons, etc.

If it helps any just make a pros and cons list of the two ways and then make a cost sheet for both. I always build overkill but that's me. It all comes down to personal comfort and cost.

 

[spadepro22]

You honestly don't need to do anything to the block if your goal is 350-400.

Proper tuning and your motor will be healthy.

I want safely make 350-400. I understand things can happen anytime, but I don't wanna take the motor close to limits on a daily base and shorten the life span.

 

[BogusSVO]

For the cost and extra expense spent to make a 6 bolt rod work on a 7 bolt crank, spend a few dollars more and just buy some H beam rods and be done with it.

The 7 bolt pistons are a clip wrist pin and not a press fit, so the NPR pistons can be run on the 7 bolt H beam rods.

 

[spadepro22]

Your gonna have to decide 6 or 7 on your own. What your willing to spend. Are you comfortable with a 7 bolt or are you paranoid it will walk? Do you trust your machinist to customize rods, pistons, etc.

If it helps any just make a pros and cons list of the two ways and then make a cost sheet for both. I always build overkill but that's me. It all comes down to personal comfort and cost.

Not paranoid of the walk because its not a 2g 7 bolt, but let me ask what is a ballpark figure on that work? Anybody?

For the cost and extra expense spent to make a 6 bolt rod work on a 7 bolt crank, spend a few dollars more and just buy some H beam rods and be done with it.

The 7 bolt pistons are a clip wrist pin and not a press fit, so the NPR pistons can be run on the 7 bolt H beam rods.

Good info here, might go this route. Are the nrps like factory replacements with higher compression?

 

[BogusSVO]

NPR makes the OE pistons.

.5 of a point in compression is not going to make that nocitable of a diffrence in how the off boost throttle is.

Going from 8.3:1 to a 8.8:1 may give an add'l 2-3 HP and maybe 1-2 Ft/torque

 

[spadepro22]

The 1g 7 is 7:8.1 right? And with the 2g pistons all be going to 8:5.1 correct?

 

[gsxtreme1987]

The 1g 7 is 7:8.1 right? And with the 2g pistons all be going to 8:5.1 correct?

Yes.