Pokher Ace

Im building some 509" 600hp carb motors and confused on advice Im getting on rods. Reuse stock rods and upgrade to ARP bolts? By that time im at the same price as Scat Ibeams w standard ARP bolts. Decent H Beams can be had for roughly 5-600 and is it worth it? And why are pro I-beams much more $$$ over H-beam?

Also on a 509 whats the benefit of running a 6.385 rod and shorter piston over a 6.135 rod and standard piston Only thing I see is the piston is roughly 100grams lighter what does that help?

FIXX

iTrader: (2)

Go with the h beams,The I beaams are lighter and cost more to mfr,more machineing involved..you want to get scared ,,price out a set of oliver rods .

a 6.385 rod will be easier on the cylinder walls,6.185 will put more stress on the cylinder walls with the ..6.385 rod will make the engine think its bigger because it will stuff the cylinders with more air due to the piston staying at tdc and bdc longer..

BillK

Ace,

If you are buying everthing including a crankshaft, the longer rods make it easier if you want to internally balance the crank because the counterweights can be a bigger diameter. The longer rods will make a little more torque because the piston is at TDC slightly longer.

To be honest with you, if your engine is low hours and not hurt I would not be at all concerned with running the stock rods and bolts at the 600 horsepower level. There is a ton of them out there exactly like that.

Just my opinion,

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

Bill Mattingly

i ran stock (dimple) rod's and bolt on 502 mag with 7lb's boost for multiple year's with no prob's, save your money end reuse rod's

n20michael

NO! If you want to get scared price a set of Cunningham or Crower Titanium rods, OUCH!

ezstriper

just remember those scat rods come from china....enough said so that being said...I would rather run the stock rods with arp bolts hands down !!!

Young Performance

There is absolutely nothing wrong with Scat rods. Also, there is nothing wrong with running the stock rods with ARP bolts in a 600 hp engine. It all comes down to economics. By the time you spend the money on resizing the stock rods and buying and installing the new bolts, you are better than halfway to a new set of rods. After you spend the $200+ on the stock rods, you still have a press fit pin. The H beams will give you a floating wrist pin. You could also install bushings in the stock rods, but now you are getting up to price of the H beams.
If you go with the stock rods with ARP bolts, make sure the bolts are installed and seated correctly. The rods should be torqued and taken apart at least 5 times to make sure the new bolts are seated correctly and won't move anymore. If they move after assembly, this will greatly change the torque values.
I have unintentionally run the Scat rods to 1000 hp. By that I mean when the project started, we had no intentions of making that much power. As it progressed, the owner wanted more and more. Had I known from the beginning, I would have chosen different rods. I was a little worried, but it has been over 3 years and a bunch of hard running (540 ci, over 950 hp, 6000 rpm, 8 psi boost). I would not recommend Scat rods in 1000 hp piece, but they can handle it.
Personally, I would go with a set of Scats or RPM's. If you go with aftermarket H beams, spend the extra money and go with the ARP 2000 bolts, instead of the 8740 bolts. The RPM's run about $350 with the 8740 bolts and about $450 with the 2000 bolts. The Scats run around $450 with the 8740 bolts are around $525 with the 2000 bolts.
Let me know if I can help in any way. Good luck.
Eddie

Pokher Ace

Thanks guys the machine shop also recommended RPM rods said with his experience they are the most consistent out of the box in that price range. Must be a builder thing Im not familiar with them at all. Now my only dilemma is 6.135 vs 6.385 is there any measurable gain with .25" Im using stock merc 4" cranks and blocks

Young Performance

If you ever have any intention of putting in a 4.25" stroke crank, then go with the 6.385 rods. You will need them if you go with a stroker crank. That way you won't have to buy another set of rods. If not, then you could really go either way.
Eddie

jeffswav

Again great advice from Eddie. I use the Scat H-beams standard length. Mine came in a kit with the stroker crank and pistons.