I-beam or H-beam rods?

[Lynn Larsen]

Hey all,

My motor will absolute max at 500HP and that was calculated based on a Dart block with 4.125 bore and a 3.25" stroke, but I just bought a R302 and am going to start at .040 over and won't even get to 4.120 for a while and will still use the 3.25" stroke. I'd like to go with the lightest rods that won't break on me. The PITA is that I am right on the edge for going with I-beams or needing H-beams. There will be little to no banging of the engine (read no drag racing), but there will be rpms up to 7-7.5K that the rods should withstand. Haven't decided on pistons yet, but I will use <500gm forged pistons w/ tool steel pins for sure. I've got a shot at a new set of Eagle I-beams for $150 (one bushing will have to be replaced; the guy screwed it up somehow, but at least he was man enough to admit it) which is hard to pass up. But one of the goals of the motor is to make it bullet proof.

So do I go with the I-beams or use the heavier but stronger H-beams???

Thanks,
Lynn

 

[James]

Hi Lynn,

My engine has H-beam rods.

SVO block

Vctr Jnr Heads

Max power is up at 6600RPM - 449BHP.

Hope this helps you with your choice.

Regards,

J.P

 

[Fran Hall RCR]

Eagle rods are inexpensive copies of Carrillo .
If you really want to make it bulletproof put the real thing in,Carrillo or Crower is the only true way to eliminate any future issues.
Remember that you get what you pay for......
The FACTORY Corvettes that run at Le Mans used to run Carrillo but they now run Crower as they are a little lighter.... /ubbthreads/images/graemlins/smile.gif

 

[Lynn Larsen]

Fran,

In an ideal world doing what you suggest would be a no brainer, but I am not made of money and, in light of what is happening with my paint job, I must keep costs down at the same time. That is why I limited to choices to the I-beam and H-beam eagle rods.

I will be using the Eagle forged 3.25" stroke, internally balanced crank. Also, I have decided upon CP pistons to keep the piston weights down to reduce the stress on the rods. I did read today where someone rated the I-beams to 500HP, but only 7K rpm. That leaves no margin for missed shifts, etc. with respect to the rpm. There is a tiny bit of margin from a HP perspective. I am starting to lean to the H-beams based on the notion of a margin of safety.

So, the question remains, which do I use?

Thanks,
Lynn

Lynn

 

[James]

Lynn,

Something else.

My engine has been designed to be driven very hard. I expect to hit 7000RPM on a regular basis at track events here in the U.K - hence H Beam. I think you'd feel better for it, even if you haven't got the slight weight saving from I beams to boast about! /ubbthreads/images/graemlins/grin.gif

Regards,

J.P

 

[Rick Merz]

Lynn,

I used the Eagle H beams in my first hi revving engine. This engine was ran for 8,500 mi with at least 1,000 of those miles at 7,000 to 8,000 rpm without any problems, and I even banged it a couple of times... OK more than a couple. /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

 

[Fran Hall RCR]

Lynn,
the Carrillo is an H beam rod and would highly suggest that style for the greatest strength even for the slight weight penalty, you may be surprised how inexpensive the Carrillos are if you shop around.
As this component is one of the most ,if not the most critical for high revving reliability dont scrimp on the motor build as it may be way more expensive further down the road....or track /ubbthreads/images/graemlins/grin.gif
Good luck

 

[Lynn Larsen]

Fran,

Of course you are right, and I am doing exactly what you suggest by looking around for "more affordable" sources. Another rod that is always mentioned as a quality pieces are the Oliver rods. Any opinions on that brand?

Rick, I know you USE your car, so hearing that from you carries a LOT of weight.

Thanks,
Lynn

 

[Lynn Larsen]

Anyone out there using Mahle pistons? In their motorsports line they have some very light pistons, 427-437gm, for 302/5.0 Fords.

They say that for the last 12yrs, every LeMans winner has had Mahle pistons/cylinder assemblies and that they supply 6 of the 10 F1 teams, including Ferrari. That sounds pretty impressive.

Regards,
Lynn

 

[Paul Thompson 'Hooligan']

Good Pistons Mahle - Ford Cosworths use them too (2.0 Turbo) giving some very impressive power outputs.

Roy's Mk1 GTD has Custom Spec Ross pistons - also very good.

 

[Fran Hall RCR]

Lynn,
Oliver rods are very good too and less expensive ..again a little heavier but as you are not running Le Mans ..yet.
They will be fine.
Mahle makes great pistons if they are off the shelf parts but the lead time is sometimes a little long if they are custom....
I know for a fact that we have run them at Le Mans and won with them..
Fran

 

[Mike Dozier]

Lynn

I believe CHP sells H-beam for $ 450....so if you're only
talking $ 300 more than the I-beams you found, that sounds like cheap insurance.

MikeD

 

[Malcolm]

To help your decision, bearing in mind budgets, if you pay the extra expense for H beam eagles (I have these and am very happy with them) you will have to pay out a little extra now. If you rev to 7000 with ordinary rods and one lets go it will be more than a little extra to replace crank, block and everything else taken out as collateral damaged items! The extra $$$ now is a security policy (not foolproof!) to give you peace of mind at 7000 rpm. Are you a gambling man?

 

[Chuck]

Anybody driving a Porsche vouches for Mahle pistons (and cylinders for that matter). They are great but, as pointed out, the lead time for custom ones can be a bear.

Lynn, get that motor in that car and get driving!

 

[Mark Worthington]

What Malcolm said. Lynn, if you really want to spin that engine past 7,000 rpm and if you don't want to tear up that nice new Dart block, you should find a way to use the H-beams. Good luck.

 

[Lynn Larsen]

Thanks, guys! I am pretty sure that I will take the conservative route and use H-Beams. Mark, the Dart block bit the dust because of $$, but the R302 that I got is no slouch either and will do just fine. I may give up a little initial displacement (4.000-.040 vs the 4.125" Dart), but I honestly don't think I will miss it. The R302 will go to 4.120 w/o having to do an ultrasound test on it, but I'm going to keep the bore passes down to save $$ initially.

Now is just a matter of who will do the machine work on the block. The guy that I was looking at hates Eagle stuff. So, I may have to take some verbal abuse for my choices. He has plenty of money and does the hipo stuff cause he likes it and is very opinionated. But as shops around here go, he has the most and best equipment there is.

Well there is one more decision to make and that is the pistons. I have a spread sheet of the contenders and now have to decide. They are JE (not SRP), CP, Probe, Ross and Mahle. The engine builder mentioned above carries 4.040 Mahle pistons for $600 and they are only 431gm. That sounds like a pretty good deal to me compared to similar pistons, but it is a bit pricey. Getting them might reduce the level of abuse if I insist on Eagle. I think he sells SCAT, but I have heard "not so good" stuff on them. I can't help but wonder if there is all that much difference between Eagle and SCAT once you get the right part. Anyway, I digress; my second choice would be CP they seem to make damned good pistons, but not cheap. For the lower cost pistons, I think I would go with Probe before Ross. I have heard bad stuff about Ross; from the engine builder above as a matter of fact. (I told you he was very opinionated.) The good thing about JE is that they have a VERY good range of stocking pistons: more choices between 4.000 and 4.120 than anyone else.

So, since you guys were soooo helpful with which rods to use, which pistons should I go with?? (this may end up being an engine built by committee

Thanks!
Lynn

 

[Ron Earp]

I like JEs. I like Mahle too, but I feel they are over-rated. I respect Ex-Porsche's opinions, but I see lots of Porsche guys (got a set in the office next door for a 2.7L screamer to go in a 911S) that build Porsche motors and replace the pistons with JE. Mahle is good but others are too.

 

[Fran Hall RCR]

JE is part of the Wiseco company now but they will still make custom slugs with no problem....
Check out Bill Miller pistons as well they are nice pieces.

 

[Lynn Larsen]

I just got a quote on Mahle for $430. Does that carry any weight??

Lynn

 

[Ron Earp]

Good price, hard to beat for the quality...