6.8 rod choice I vs H
 

Ordering up the pistons and rods here shortly for my 400 stroker build. 4.25 scat forged crank, should be 500-550hp. By all accounts the pn# 2-ICR6800-7/16 I beams should be completely fine at my level and $200 cheaper, is there any reason to upgrade to the pn# 2-454-6800-2200 H beams? Also I don't think my power level warrants the arp2000 upgrade and plan on using the 8740 hardware choices to save $$$. But I'm looking for opinions from the great mind pool here, please and thank you.

The rod choices

Butler has the H- Beams for $543

https://butlerperformance.com/c-1459...d-journal.html

You don’t need the added strength of a H beam, but besides that the H beam design keeps a lot more oil kicked up around the crank.

So this is where my OCD kicks in and freaks out about the thought of running a scat crank with eagle rods lol. I know there would be no issues what so ever, but for some reason it just bugs me.

I went with ARP2000 and H beams.Tom

I get it re: OCD.

I assumed dollar amount was the main concern based on opening thread, once checked out by the machine shop, it’s all the same and likely from the same Chicom foundry.

Well it is budget driven but the budget is blown anyways so... Lol. More so just wondering at my power level if there is a reason to upgrade. I have heard the same about H beams causing more windage as well, which makes sense due to their design. I'm fine spending money where it's warranted, like upgrading to arp2000 hardware on the I beams is only $70 more.

I had the same decision also. I went with H beams and arp, same as tom s.

Have a set of stock Pontiac length Crower I beams in one 455HO bottom end.

Few months ago began watching for a set of 6.7 or 6.8" BBC I beam rods for next build.
Would like to get some feedback on total gram weight of various aftermarket BBC rods in 6.7 or 6.8 length. Am sure many have gone this route, anyone like to share?

My latest build is a pontiac length and pin.Tom

Seems like I'm going with the scat I beams.

In reality, either rod will work in your application. “I” beam rods are actually stronger than “H” beam rods but are also substantially heavier as well. Be advised that nearly ALL offshore forged rods( Eagle are offshore forged rods) need a bit of touching up on the big end and on the pin end. Molnar and SCAT seem to be the exception. Consider this: both Oliver and Carrillo rods are considered to be the ultimate in strength in domestic forged rods; both are “I” beam construction.

My Carrillo rods are H beams?Tom

I don't know about either being substantially heavier than the other. I think the H beams are advertised as 810 grams and the I beams as 820 grams.

Just get Molnar H beams and be done with it. They are the best rod for the money period.

I went with the Molnar H-beams due to their quality and the weight savings over Eagle and Scat

So looking at the molnar H beams they come in around 749 grams which is significantly lighter. That sounds like enough to sway me and make everything happier at rpm.

I vote H-beams. Better to have them in case you want to add power later on down the road. Over kill is the way imo...

Tom, Carrillo produces both. The Carrillo rods I’m most familiar with ( SBC sprint car rods) are “I” beams. Fantastic rods IF you have the budget for them. I’m going with Pontiac length/BBC rod journal Molnars. Did you ever get your 301 based RAV built?

Lots of answers from your lowest cost Eagle H-beams to the Scat I beams to $2000.00 a set Carrillo connecting rods for a 500=550 HP Pontiac V-8 that may see 6000 RPM's a couple times? I love spending other peoples money as much as anyone, but yiikes. A stock set of cast Pontiac rods would work just fine in the stated application and HP with a set of ARP replacement bolts if the rods were reconditioned properly. But that's a big IF. So nearly everyone replaces their connecting rods now. The SCAT I beams are so much better and stronger than the OE Pontiac rods, I just can't imagine needing anything more expensive. Are Molnar, Oliver or Carrillo rods better? Absolutely. But is a 1000% safety factor really needed on an engine that's going to make 70 HP per cylinder? I have found SCAT parts to have much better finished dimensions out of the box than Eagle. But have them checked anyway.

There’s a set of 6.8 rods for sale in the Performance Parts section . . .save some money!

https://forums.maxperformanceinc.com...d.php?t=877395

OPH this week I weighed some Crower Sportsman 6.625 833 gm. Crower billet 6.625 908 gms!

My 500" IA has 6.625 SCATs and so far so good shifting at 6500. They did not need any resizing when we built it.

There is a set of NIB scat 6.8" h beams on eBay right now. Can't think of a reason not to buy them They are $490 but accepting offers.

Thank you! I, much like everyone else can get carried away. And a hundred here or a hundred there really adds up in the end.

i have eagle H beams and a forged eagle crank, so far so good, maybe 4k miles with a lot of hard driving. at some point you just have to hope the engine builder did their job or else measure everything and assemble yourself.

Scat makes some very high quality parts, machining done in house from what I understand.

Recently bought a set of four 5.7” H-beams w/ARP 2000 3/8” bolts (air-cooled VW) for $291.58, with tax and shipping about $340. Also bought one of their 82mm (3.228”) forged stroker crank for the same engine for $350. A guy I know who builds a good number of VW engines tells me that the Scat rods are his favorite with one reason being accuracy and says their cranks are just as good.

I’m running a set of stock dimension Crower I-beams in my 421 that were originally purchased in the early 1990s for around $900, now translate that into today’s dollars. :eek:

This was back when the only good aftermarket choices were those along with BME aluminum and crazy expensive Carillo. Be thankful you’re able to purchase nice forgings for a very reasonable price.

Bought some generic 6.800 BBC rods off eBay a few years ago. 826 grams.

The Eagles at JBP are $543…

That said the I beams sound like more than adequate!

The problem with Eagles and many inexpensive I beams is, are the big end and small end on spec ?
Every cheap set of China rods I have ever bought were tight. Needed the big end honed.
Molnars are dead on nuts. And if they are not for some reason Tom will send you a call tag and switch them out on his dime.
Can not ask for anymore than that.
Their regular H beams go over 1000HP NA all the time.
A street engine will never hurt them.

I know it stinks that the small end is tight on most of the less expensive rods, and curious what a machine shop charges to run a hone through them? And/or how much time involved since shop rates may vary.

So yesterday pulled out a few rods I have and weighed them.
The earlier wt on the Cower Billet was with bearings so I pulled them out for apples to apples

Crower Billet 6.625 853gm
Crower Sportsman 6.625 833gm
Cast factory rod 896gm
Tomahawk 5149 I beam(still in a PPR box! 2013) 834gm pictures included

Crower Sportsman 6.8 Pontiac rod 850(854 on their sheet)
SCAT 6.8 BBC journal 828gm

BBC journal bearing was 48 gm.

Well I just ordered a set of NIB scat H beams that were on eBay for $495. Hard to beat that

Tried sending an offer but he didn't respond, and didn't want to miss out so I just paid full price.

I can best answer your question this way. Small ends that are tight can be easily fixed if they are simply tight. (not greatly tapered or out of round). this process takes 1/2 hour maximum to open them up to specs for a set of 8. If you are having additional work done at the machine shop or know the folks and have a working relationship with them, it may be a no charge deal. As a walk-in don't know anyone, they may charge you an hour. The big ends are much more of an issue. Again, if the big ends are just small, it's the same as the small ends. 1./2 hour of labor will fix the set. Unfortunately, it has been my experience that the big ends can be really messed up. If already too big, you are screwed. First, you have to remove the hollow dowels from the rods. They can be difficult to pull and usually can't be re-used. Then the rods and caps have to be cut, new dowels installed, and honed to size. This entire process can take 2, 2 1/2 hours. So essentially, your rebuilding the new rods. The last 2 sets of rods we had through the shop from Ohio Crankshaft, all 16 rods had to be completely rebuilt before they could be used. They had taper as much as .0015" and out of round as much as .002". No way they would have lived in service. One set was SBC, the other BBC.

So in this case, buying a set of cheap rods, for $450.00 and having to pay $300.00 to get them fixed so they can be used puts you right in Molnar range. I have never had to service a Molnar rod new out of the box and I check every one.

Good info there. But not everyone can afford to buy the best of everything out of fear. I'm trying to build a very budget conscious stroker, not cheaping out on everything but solid middle of the road stuff. Like my speedmaster heads, are they the best, probably not. Will they work for me? Hopefully. But after talking to the forum I went with a forged crank, however even that I got for $800 using a sale and coupons. I love molnar, kinda wish I would have splurged and gone that way from the beginning but there are plenty of people running scat making way more power than me. Plenty running eagle cast cranks and budget rods too. $200 saved on the rods, $250 or so saved on the crank, it all adds up. Just that makes it easier to swallow the cost of a roller setup.

No argument there. We all have a budget and not every Pontiac engine build needs to be 8-10K. But spend the $$ wisely. Buying any internal engine part from E-bay needs careful inspection. I would have those E-bay, (SCAT), connecting rods checked for size, taper and out of round at a trusted machine shop. 95% + chance they are all great and within tolerance. If you don't want to go that expense, at least at a minimum, plastigage all 8 connecting rods on the crankshaft, clean and dry. .002" minimum clearance, .0005" maximum taper. Out of round can't be checked with plastigage. Make sure the rod bolts have plenty of "Extreme Pressure #3 grease" on the bolt threads and under the bolt heads. That's what SCAT specifies for their bolt torque. There should be a small pack with the rods. If not, Summit and others sell it. Good luck with the build.

https://www.summitracing.com/parts/scc-scp-3lube

Yup they'll get checked out. I have an excellent machinist who is one of the smartest guys Ive met. Everything is getting checked with him when he balances the assembly.

Thanks - great information as usual!