A few 6 bolt questions!

[dumb_ricer]

First off, the 6 bolt Ross Race pistons will fit on the 1g BigRod's without machining correct?

Next, what is the weak link on the 1g/2g combo. Is it the pistons or the rods or do both of them have about the same strength as far as max power goes.

Is there any downsides to running a cast rod on a forged piston? I have not done much research on that. I know the LS7 new Zo6 motors are Ti rods on cast.

Are ARP main stud's recommended on a buildup of a 6 bolt. I know I have heard some bad things about using them but im not sure if that was with 7 bolts and crankwalk or with 6bolts and something or another?

[1ViciousGSX]

1. 6 bolt pistons should fit 6 bolt rods without any problems. There is only an issue when trying to run 2g pistons on 1g rods.

2. I think both the rod and pistons are good for about the same power levels. If one had to be stronger then the other, the piston would probably support more power than the rod would.

3. Forged rods only please.

4. Mains studs are not the norm for the 6 bolt engine. You can run them, but the block/mains have to be recut/machined for it to work correctly.

[Shane@DBPerformance]

You can't just run any off the shelf aftermarket piston with the stock rods. Most pistons are designed with a full-floating pin. You would have to custom order pistons with a tapered or press-fit pin for your application.

Who knows if the 1G big rods or stock pistons will go first. RPMs will probably kill them before horsepower.

The downside of running a stock cast rod is the required use of special pistons, and the rods probably aren't as strong as aftermarket rods. With how inexpensive Eagle rods are, you might as well save up for a set of them before building a motor.

Main studs are not really needed. They are require a fair amount more machining to be uses correctly. A new set of stock main bolts will hold just about anything that you throw at them.

[Raptor]

I actually agree with shane on most of this, there are a number of factors that come into play to make a press fit pin work correctly with a piston designed for a floating pin. I have seen it done pretty ghetto a few times and it makes me cringe. Just pony up the few extra bill for a set of eages and don't worry about it. Only thing you may run into with Ross/Eagle as a combo is the rods may have to be pin-fit. Not an expensive process, but something to consider.

As far as the main studs go, if you are only dealing with power levels that are okay for stock rods <500 whp, you definately don't need them. If you are after more than that, it is worthwhile to consider them, at upper torque levels, the caps do have the capability of shifting and ruining your month. We don't have the option to go with a fourbolt main, adding any additional strength for reasonable money is a smart investment. I have always known this, seems a few other builders are starting to come to the same conclusion and advertising it as well so I am told. At your level though don't bother, just make sure the stock TTY main bolts get replaced, they are not designed to be re-used and are pretty inexpensive ( around $30 per set).

[Tsi]

Basically if your thinking of rebuilding a motor, you need to ask yourself what kind of horsepower you want to make. The 1g rod, 2g piston combo is said to be good up to 450whp, requires a little bit of machining but alot of people use this combo because it is less expensive. I am currently running Ross forged pistons on 1g rods and I am happy with it. No machining necessary, just a pin fitting by the machine shop on the 1g rod, forged piston combo. As far as main studs go, again how much power are u wanting to make, like the rest of them said, they are not needed but if you plan on making over 500 hp go for it.

[Raptor]

Just curious Tsi, it sounds like you had the rods resized to allow the pin to float, if that is the case: Did you have them bushed and have oiling holes drilled? Did you switch to ARP rod bolts and if so, have the big end resized as well? I know a lot of people forgo these things, I wouldn't recommend it. People can get away with crazy power and setups that are just a bad idea in many cases, it just doesn't make it right. The reason I ask is simply because if the correct choices are made in machining the 1G rods, the cost is close enough to the eagles that it is really a mistake. I will no longer build engines with 1G rods for that very reason. That and most of the time if the customer is going to cheap out on the rods, one of the most critical decisions, they will cheap out down the road somewhere else as well and nothing but problems will come from it. Not so much trying to slam the people that are running 1g rods/forged pistons, I would just like to see people start considering their shortblocks more important than all the bolt-ons. The shortblock is a bit more difficult and expensive to change if you decide you didn't do it right after the fact. Start with a good foundation and go from there. If you change your mind mid year and want to shoot for 600, you will be regretting the 1g rods.

[Tsi]

Yes my friend I had all that done ;) ...did lots of research on that, and had a guy that knew what he was doing and did it for me for cheap, thats why I went with that combo. Also I'm one that isn't looking for a day to day track car, just something with some get up around 300-400 hp

[dumb_ricer]

His power goals are dependant on money, so definitely no need for the mains then. Why would you need to machine it to run Main Studs? They basically do the same thing as bolts but much more effiecenty and more safely. I dont see why machining would be necassary for them. Why is it needed/recommended?


The reason I am wondering if forged/1g big rod will work is because by the time you buy .020 2g pistons and rings and get the rod machining done you could have just as well bought a set of forged pistons. People have stock bore 2g pistons all over for cheap but in my opinion to even semi properly build a motor you have to bore the block and get it honed well. Everything I have read/seen leads me to believe that cylinder trueness and preparation is the most important part of machining. Realistically the power he will make will never exceed 550whp in my mind, and at least not on this motor.

So what would be the "cheapest" route to go while still having at least 1grod/2g piston strength? What does machining cost on the 1g big rod to make the piston fit on? Do you think just running new mitsu 2g pistons and mitsu rings would be the smartest way to go cheap on the motor? What about the Speed Pro and other non forged pistons available? Are they as strong as the 2g pistons?

[MustGoFaster]

"His power goals are dependant on money..."

Money is dependant on time. Set your power goals and build for them. And remember that power is addictive.

[Raptor]

Anyone that understands engine building will tell you that studs, put higher torque loads on the mains or rods or whatever application you use them in, it makes the main OOR and therefore requires an align bore/hone or in the case of a rod, resizing. Make sense? Not much different than boring with a torque plate, same principles apply.

You lost the rest of my input on how to do it as "cheap as possible". Not to be a jerk, like I mentioned above, your shortblock isn't the place to cheap out, personal belief and I am sure there are enough people here that will give advice on cheap setups. BTW, Ryan is 100% correct on his above comments IMO.