Been going back and forth on rods for my Tomahawk, my crank is on order finally and setup for BBC 6.8 rods naturally. My options are 1. Billet with L19's some say the L19's are a gamble due to them rusting so easy, where as some builders have been touching them during assembly for years and never had a bolt issue. Billets are of course $1300 plus, which while not terrible still stings when there is so much other stuff to buy. 2. Eagle rods, they are rated to 1200 with the L19's but a $450 set of rods in my 30k engine ehhh idk. I've seen Eagles hold way more power at much higher rpm than I will be playing with but still..... 3. A nice American machined I or H beam, like Lunati,Callies,Howard's etc not that much more than Eagles but pretty much everyone agrees they have better consistency and machining, but they carry less of a "rating" My head hurts.....
I have the oliver rods for my Tomohawk but JW said Molinar offers rods that are the same as olivers. Maybe He will chime in and comment.
The Howard's Billets are $120 each with ARP 2000's only avaliable in 6.700 tho so piston would need a taller deck to work with the 4.25 crank , I assume thats possible rite? Possible pitfalls?
I would call molnar and talk to them, I think they all come with a made for them special arp2000 bolt, they have more choices than they have listed. And for 600 or so reasonable. I think like most of the rods they are made across the pound, but not all foundries over there are the same, molnar finishes all state side. The ones for our BBB needed nothing, they were spot of in size, and even weight. I got the part number from them found them on ebay for under 500 shipped, so I know they were just normal production parts, not something they put extra time in just cause I called and asked a few questions and ordered from them. Our motor is not finished yet but so far I'm happy
Privately I shed a couple of tears every time someone uses eagle parts. I like Carrillo. Then Oliver and then Callies.
Ignore the hp rating. That's more intended to target the intended market, kind of like an rpm range for an entire engine family's cam. No worries over the rod bolt with a lower rpm deal. Anyone dealing with the machining and engineering of highly stressed parts will confirm that Chinese sourced alloy is not comparable in quality with materials from American or other origins. 'We' made billet rods and other highly stressed driveline parts for aftermarket, OEM, OEM backed racing efforts, etc.. The alloy can still be '4340' for example, but there's a wide range what meets that recipe. Our steel suppliers introduced more Chinese sourced bar stock as American plants were shutting down. We had many p/n's in the 100,000 piece quantity range, so we aren't talking about a small company. We also saw our first failures in decades. We knew something was up after having to change all of our feed rates, SFM's, incorporate more high pressure coolant thru processes (just to name the basics), just for our very expensive high end tooling to survive the production runs. Now the real mystery...what's going to happen after heat treat? What we found after tracking each alloy batch was that some had hard spots, inclusions, banding...and any variances in the pre-hard condition affected the end result. I'm fairly certain the failure rates were below 1%, but we intended that from the start. The unpredictability of the alloy and nature of the process mean that they simply take their chances. Who knows why any part fails? Spend the money on the good stuff.
GRP with the pro material. I run these aluminum rods in street engines and full-race engines. They are far superior to any aluminum rod of the past,and the material can withstand the hot/cold cycles of a street engine. About $800.00-$1,000.00 for a set.
I had Crower build me a set of 7.250 Billet Rods back in the mid 90's, ..... after installing them I never thought twice about a rod failure, .... and they never failed while in my engine. I believe the ARP 2000 rod bolts have a good reputation and as far as the L19's, ... there has always been talk of Hydrogen Embrittlement. Just keep them clean and oiled. Not sure if I like the idea of having expensive bolts holding my engines expensive connecting rods together, but they could fail if I touch them. Larry
The bigger problem with making parts from 4xxx pre-hardened material is it's tendency to work harden when the tools go dull, have coolant issues or use incorrect feeds/speeds. Now couple that with the uneven hardness of the broken carbide and pop-can infused chink stock itself, even when it falls in the average range it's supposed to. I will 100% agree that the Chinesium stuff can be tough. So here's what happens...when the machinist finds a dulling tool or any other normal production/process issue, appx. 4-20 parts before that are some perfectly good parts that have places in them that are much harder than the 28-32 Rockwell condition they are supposed to arrive in. Where do those parts end up? This is with 'billet'. I am unsure about certain forgings but I suspect it doesn't help things. I do know that when you can cut this stuff like butter for decades and suddenly the new stuff eats $1000 drill bits...it ain't good.
I would use modern aluminum for this one too. I've never had a problem with them and the weight reduction to the assembly helps everything.
Yes, you can use a billet/forged rod for around 1300-2300K, but I would use a set of Molnar Forged H beam rods, for around $600.. Your not going to break an aftermarket steel rod in that application. so don't worry about that. Forged, Billet, H beam or I beam, probably really not a concern here. It's heavy pistons and high rpm that kills rods. What your really buying is product quality, and I will tell you, the last set of Olivers I used, I was disappointed in how well they held the sizing. Lots of these older companies are going thru buyouts, and the farther the guy running the machine gets from the founder of the business, the more they often will let slip past. I have used about half a dozen sets of Molnar rods now, from their BBC stuff to our new 470 BBB rod, and they continue to impress me with their size and weight consistency. Love being able to pop in a set of quality rod bearings, like the King HP bearing we use here, and measure up a set, and have the rod clearance all be within .0001.. in about 10 sets, not one has varied from the recip/rotating weights that are listed on the box, more than half a gram.. now that's accuracy, someone really cares enough to put together a matched set. That's what you get when you deal with a small outfit like Molnar.. much higher attention to detail.. the owner of the company might just be the guy doing the final hone on your rods. And you can't get anyone who cares more about the product. In this country, we often times confuse product quality with price. While there is a kernel of truth to that logic, once in a while you stumble across a mid price product, whose attention to detail puts it on par, or above, a more expensive competitor. l believe Molnar is one of these companies. I encourage you to call and talk to Tom, tell him I sent you. JW
I know alot of times your paying for the name, but they got the Name reputation for a reason, but like you say alot of the more mature manufacturers have been sold out, and I know all to well what that means. To be honest, I will be babying this thing 80% of the time I'm not caging my Orange Car so other than the very limited occasion I make a 1/8mi hit it will just be out cruising around. Money saved on the rods would almost buy the pistons, or the cam etc..gotta make a decision soon so I can let Mike know the weight. It's going to be a hydro so 6200 or so is all it will need to make stupid power
As I stated earlier I was impressed with my molnar and after talking to Tom it's why I made my mind up. I did not know how true they were till at the builders. I told Tom on phone what we planned to do and the rpm range going upwards towards 7000 but planning on making every shift on the track at 6500, tom told me if I ever broke one of his rods he would buy me any other manufacturers rod of my choice. I thought it was a sales pitch. But after I bought my rods through rpm lab off ebay, opened then up. U called Tom to tell him how great they looked, a few days later in the mail came the letter from stating in writing what he told me on the phone. He ever took the time to explain why the 2000 series bolt he uses is better than the sardar ones from arp and why he had them made the way he did for his rods
