If I may add some info here I think I could give you some added insight and collectively place the information already given.

First you don't build a motor around a cam. I understand that you already have that cam, and it is fine for many applications. Alot of folks run it with stock cubed cars with noproblems, although it does require head work and a free flowing intake and exhaust to rech its maximum power. The drive train and gearing also play a role in that cams ability as well, but thats for another article.

To me the difference of going cast vs. forged is the costs. When comparing kits that are available you can se that it is just as cheap, if not cheaper to buy new than to have the old reconditioned. This pertains only to the rods as that would be the only part useable for the stroker. For just a few hundred dollars more you can get a complete forged rotating assembly, balanced and ready to install delivered to your door. The added costs of going forged vs cast and hypereutectic is minimal when you add the "reliability or durability" factor in it. This is not to argue that big hp strokers have not been made using cast or hyper pistons and been reliable, just a bit of insight.

Now component vs component which is best? Thats like asking who is the hottest woman or whats the best color, everyone has their bias. Most companies are made in the same forging plants overseas and they are imported here and then shipped to the respective factories where the place the final touches making them their own. For American steel you are going to pay a much higher price, thats why you see some that are comparable and some that are thousands more.

Again as Caprice points out that a 355 may be all you need and want, unless you really want that 383. I must stress this point very very much that machining is ABSOLUTE, no matter which components you decide on you must not skimp in the area of machining. Thats what makes the difference between a good motor and a great motor.

In addition to this you must also respect the fact that quality fasteners should be utilized throughout. Thats what holds everything together and thats where reliability is going to come into play. Using a 6" rod over a 5.7 does have added benfits, and quite a bit more than what most tend to think. You are taking the force placed onto the cylinder wall and adding it to the directional movement of the piston, thus making it easier to wind up, and creating less friction on your parts. You should however pay close attention to keep the pin height out of the ring lands in a street driven motor.

A few other tidbits for you. If you go 383 an HBEAM rod will clear the cam, therefor you will not have to run a small base circle camshaft. You will also gain an enormous amount of strength with that rod. The con, they are heavier. You can offset that additional weight by using a lightweight piston, look for one with a compression height of 1.250 or less and that will make for a fast revving smooth running motor, however any piston will work so long as you keep your eyes on the fine details.

I hope that helps ya some

Jack

 

Jack: I'd like to know where you get the information about a 5.7 v. a 6" rod. This has been tested by many engine builders, most notably Reher-Morrison and they found no meaningful difference (differences on the order a few tenths of a percent at best) between long and short rod motors. It all stems from Smokey Yunick a very long time ago in a very particular situation. And with Smokey, people never really knew exactly what he meant, or so I am told. The quote below is from Darin Morgan, formerly of Reher-Morrison. He has since started his own shop. Absolutely one of the best engine builders of the day.

People look at what Smokey Yunick said and they take it out of context in my opinion. He said you should put the longest rod YOU CAN not the longest rod YOU CAN CRAM JAM OR MANIPULATE into the engine. I see people all the time screw up the engine combination to facilitate some preconceived ideal rod ratio and they wonder why the thing wont turn up and make power. The difference in the GM 358 NASCAR test engine from 5.250 inch long rods to 6.1 inch long rods was maybe 2ft/lbs and 2 HP. Not much to worry about. That satisfied the GM engineers that there is nothing there. Does a short rod make more TQ? Does a long rod make more top end power? It probably does but its such an insignificant amount, its not even worth messing with! If there was a major advantage or power gain in this, it would have been proven a long time ago and we could all put this to rest but no one has. I wonder why???????????

Darin Morgan
R&D-Cylinder Head Dept.
Reher-Morrison Racing Engines
1120 Enterprise Place
Arlington Texas 7600

Rich

 

One other thing - I would use a long rod in a very high rpm engine because the rod -piston combo will have less reciprocating weight in a long rod combo. This reduces rod bolt stress. Not an issue in what we are building here though. IOW, the differences between a 5.7 and a 6.0" rod for a 3.75" stroke SBC operating at anything less than stratospheric rpm is insignificant.

Rich

 

I think the biggest thing with my motor is that I am not trying to make a big high hp motor. What I am striving to do is the complete antithesis. If I wanted high hp on a budget I would do stock crank, forged rods and forged pistons, and spray the crap out of it until it blew up.

I am building a low (low for today, I mean) hp motor for a weekend car. Even though forged is only a couple hundred more, that is more power handling capability than I would ever need. I beleive hypereutetic is also a little bit lighter (don't quote me). I also do not see the reason to spend more money than I need to. I work in a construction oriented field so this is the way I see it. A homeowner that does not perform their own in home work/maintenance goes to home depot to buy a cordless drill. They could pick a $50 black and decker/low cost dewalt/similar brand, or spend 200+ on a makita/dewalt xrp/milwaukee/similar brand. What will this person get out of the better drill? A ton of power, the ability to charge their battery in 15 minutes and have a back up, and the jealousy of their neighbor. Other than for those reasons, the better drill does not offer them any advantages. I see the forged motor as being something that does not offer me any advantages, other than less money in my wallet. I don't think that a super forged motor for a street car is a necessity. I am sure I would need my mains splayed way before I would require forged internals. I might be looking at this whole motor thing totally incorrectly, though.

I am looking into dcr and scr, which is why I am using the cam's specs. The car has been proven to work fine in stroker motors. Could I make more/better power with a custom cam? You bet I could, but to me the additional cost is not worth it; unless my builder tells me I need to get one. I am also concerned about the ability to run on Arizona's crappy 91 planet saving gas. The stuff stinks, no way around it. Last thing I want is to start the motor and blow it up.

I am very happy about hearing about the rods though. As a replacement for my rods I was looking into the scat i-beams. I will now look at the eagle h-beams. I defintely do not want to have the inconvenience of having to get a small base circle cam ground and set up.

machining will not be skimped on. I talked to my builder and he told me the machining is way more important than any exotic parts I might be able to find. 4340 zebra metal alloy doesn't mean a thing if the machining isn't better than perfect.

rskrause (or anyone with this experience), would a set of stock rods with lower miles have a lower cost of reconditioning? Or is it all the same once they are used?

 

Actually that quote was also in reference to specific engines as well. I understand what the theories and concepts that apply to each are, and for example the 6.0 vs the 6.125 rod the differences there are actually negated in a normally driven vehicle because of the overlapped ring lands.

With that being said it is simple physics. I am not trying to denounce or even argue the point but I would like to allow my opinion on the matter as I share it with several others and it has long been passed down. I have somewhere the data on the test between the two, and the hp advantage is not huge nor is the torque, but the efficiency is, as is the longevity of the parts.

I know that I need not explain to you the sidewall forces emitted, but in principal the same thing that makes a breaker bar work more effective than a standard short bar are there. The rod allows for a better angle up and into the cylinder bore, albeit fractions of an inch, and it also leaves the piston in the sweet spot longer again for only fractions of a second. It IS less stress of the piston, wrist pins, and rods.

So by that reasoning I apply the fact that is cost no more for a 6.0 rod vs the 5.7 and the advantages are there to be had. The topic that made this come to light was the words reliability/durability.With that being said can you think of any cons against using that rod length over a 5.7? Thats essentially what I was going on.

 

There is no denying the fact that the stock rod is strong, as is the crank. What was being said that if you are looking at the costs of having a rod recut, and then in return rebalanced it is cheaper to get a new rod or set of rods.

In reference to the drills. The difference is that eventually the cheaper one will go out long before the other. Now a good buddy of mine, I believe he is a member here as well just built a motor doing exactly what you are trying to do to see what he could get out of it and how much is was going to make etc. It can be and has been done before. There is nothing against doing so. It is strictly my opinion and belief that especially if stroking because you have to get everything new anyways, that the piece of mind is worth the few hundred more.

 

I appreciate it very much. The wonderful thing about forums such as these is the ability to garner information from a wide variety of different people that have all had their own share of experiences.

....how's your buddy's motor holding up by the way? Hopefully you are not speaking from his experience?

 

I am not speaking from his, I have my own to derive from I have just been around this for a very long time and I can appreciate what hindsight is all about. I was once told and never have forgotten the words "If you are going to do it do it right the first time. Why spend 75% now to do it half-arsed then spend more to do it again real soon."

As for my buddy here is his thread, and I apologise if the thread from another forum offends but I don't know how else to link it
http://www.z28.com/forum/showthread.php?t=117978