I wanted to know the differneces on "H-beam" rods, and "I-beam" Rods.
Also the advantages and disadvantages to both.
What do you think is most sutible for a 383 stroker engine.

 

The desciption of H beam and I beam refers to theshape of the rod if you cut them in half horizontally one looks like a H and one looks like a I. Thethree main differences I see are cost, stength and weight... the torsional strength of the H beam is alot greater than the I beam. Though I know guys who run I beam rods in 850 hp sprint cars to save on weight(titanium). The I beam strength ratings will vary depending on design, cap screw size and construction(material) and brand, choices include powered metal, stock cast, and forged, metal types aluminum, iron, steel titanium and Ive heard carbon fiber(not to sure on this one) in "normal applications" aftermarket we are generally looking at forged steel is two types 5140 and 4340 the cheaper eagle rods are 5140 and are rated at 500hp Ive seen some of the 4340 rods with good bolts rated to 750 hp scat or eagle.. olivers may be rated higher the H beams are rated 750hp and up.In my opinion the choice depends on budget use and horsepower levels can you tell us what you are building and for what?

 

My budget for rods doesnt matter cause i want them to be able to hold the horsepower i want with reliability. As for horsepower levels i am looking for somewhere around 450hp out of a 383 stroker. A lil later after i build my motor i think i might put a 100 shot of nitrous too (not sure about it yet) But definately i am looking at getting 4340 forged rods, just not sure if i should get "H" or "I" beam rods.

 

The 400 we built should be around570 hp n/a originally we ordered the better I beam because they were rated at about 750 hp and were lighter but they didnt come in so we opted for the H beam, the H beams are overkill in our engine the stock chevy block will be well into the danger zone before either the good I beam or the H beam will anyhow. My machine shop saidto avoid CAT rods. What block are you using(2 bolt or 4) crank, pistons? Another thing that the machine shop guys on here might be abile to answer is will clearancing the H beam rod in the 383 be more work than the I beam??

 

Im using a 2-bolt main 2 peice rear main. I was thinking about having the block machined for splayed mains, is it a good investment for the horsepower im looking for? Or is it a waste of money to do that, and will the 2 bolt mains hold 500hp? The crank im gonna use is a 4340 forged steel crank from a 383 stroker kit. Pistons are gonna be Keith Black Forged 5CC Flat Top Pistons.

 

In general the rating for a 2 bolt main block is 400hp some will say they go over this and they may with good cap and studs but its taking a chance. Splaying using the splayed 4 bolt cap is what I would do if you are going to use the 2 bolt block but be prepared for $500+ to do it registers need to be cut studs installed, line bored and honed. Its cheaper finding a 4 bolt block they claim they are good for 500hp. The splayed caps are the strongest with ratings aroud 600 hp. Personnally after building the 400 I think anything over 550 600 hp I would price out doing a big block. And anything over 500hp I would be looking at a Dart block and pricing it out if cost isnt a issue that is....

 

Splayed caps will have more strength than a straight up and down bolt. They have "splayed" anchors on bridges when they are built. Look at Iron Eagle for a 383 stroker kit. They have rotating assemblies up to 800 hp. I'm using them for my 510 HP 383 with H beams.

 

well i was reading about i beam and h beam rods. The main characteristics of the i beam rods that are different than the h beam rods is that they are lighter which give quicker revs and more horsepower. They are a little less stronger, but the forged rods can still hold up to about 700 hp

 

Assuming you are talking about 4340 forged versions either way; the H-Beam are stronger but we have been avoiding them on stock blocks. We have broken into the water jacket on many blocks while machining for rod clearance and I tend to worry about how thin the ones are that did not break through. I-Beam rods generally allow for .050" to .075" less material to be removed from the block and that is a lot extra when you are talking wall thickness.

I use a lot more aftermarket blocks these days because of reasons like this and of course other strength areas too. I always think back to the old days when we regularly built engines with stock rods and ARP bolts and ran the daylights out of them. For the most part, they held up very well.

If you are making under 500HP, go with the I-Beam rods. By the way, Eagle SIR rods seem to give us the best fit in the block. By the way, do not forget to check your rod to cam clearance as you may need to grind the rod a little for that too.

 

On the stock rods if you just used the factory bolts what ballpark power could they handle? To change the stock bolts to arp they need to be pressed would you normally need to resize the rods?