Carrillo VS Pauter

[Ben M]

Building a short stroke 2.5 liter engine for racing. Advise on which rods to use would be appreciated, Carrillo, Pauter or ?

Thanks in advance!

[MBruns]

I use both in our engine builds, and have no problem with either, Since Pankl bought Carrillo the price has gone up a good bit which makes the Pauter's an excellent value.
Mike Bruns JBRacing.com

[AlfonsoR]

Mike,

Just an observation from reading posts over the years, but when people have a questions or possible issue, I often see "call Brian Pauter..." This gives me the impression customer service is top notch. Is that correct? Is Brian the owner?

[MBruns]

Brian is the guy, his customer service has always been top notch !
Mike Bruns

[safe]

R&R sold by LN engineering seems to be reasonably priced??

[Henry Schmidt]

There are several beam choices that are popular. Most commonly used are H beam and I beam styles. Less common are A beam and X beam. Most factory rods are I beam design and this was done to aid in forging for manufacturing. This design is very strong, but tends to be slightly heavier than an H beam. The I beam has preferable windage characteristics over an H beam though. However, most people choose the H beam due to weight and strength characteristics. I'm not saying H is stronger than I, but you can have a lighter H that is just as strong as the I beam! A beams are for lower horsepower applications that require a very light rod. X beam rods, while being strong design, tend to be very heavy, as if they are lightened they become weak.
Generally speaking the X beam rod is the poorest design but craftsmanship and high quality materials offered by Pauter overcome this less desirable design.

[KTL]

Another thumbs up for Brian Pauter. Sent him some old Pauters that needed rebushing (previous user upsized them from 22mm to 23mm to use "Carrera" Mahle motorsport pistons) and asked that he crack check, check the big end bore & C-C length, rebush with 22mm size, plus some new ARP bolts. Turned them around quickly and did a great job.

I think the Pauters + ARP bolts were a contributing factor to NOT throwing a rod thru my case when I had a major engine failure.



Not saying Pauters are better than Carillos because I have no idea. Just saying they are a darn good rod. Stock rods most likely would have caused considerably more damage and i'd probably be buying a whole/longblock engine instead of being able to recondition most of my engine.

[chris_seven]

Originally Posted by Henry Schmidt

I'm not saying H is stronger than I, but you can have a lighter H that is just as strong as the I beam!

I have been interested in the basic design of con rods for some time and as manufacturers of I-Beam Rods and H-Beam Rods always claim their product is the best it is difficult to make a good judgement.

In general beam theory the difference between the two designs is concerned with the width:height ratios of the two sections.

In an H-Beam the width of the flange is equal to or greater than the height of the cross-section and in the case of the I-Beam the height of the cross-section is greater than the width of the flange.

The strength of a rod in tension is simply a function of cross-sectional area – its shape makes no difference.

The stiffness of the rod in terms of buckling and flexure, however, produces significantly different results and the Second Moment of Area of the section needs to be considered.

For an equal stiffness an H-Beam would be just over twice the weight of an I-Beam. This means that for an equal weight an H beam has only 40% of the stiffness of an I-Beam.

This analysis doesn’t take into account the increased volumes around the big end which reduces weight difference but is does mean that for a given stiffness an I-Beam would be significantly lighter than an H-Beam.

If this were a complete picture then I-Beams would surely be the rod of ‘choice’ and would easily out perform H-Beams and some manufacturers claim that the only advantage of the H-Beam is that it is easier and hence cheaper to manufacture.

The H-Beam shape does, however, have one advantage, and this is in the area of torsional rigidity. It is well understood that a piston will rotate around a cylinder axis and produce torsional loading in the rod.

H-Beams are torsionally rigid in the direction of crankshaft rotation and this does provides some benefit with regard to compressive loading as two wide flat pieces of steel parallel to the plane of rotation provide good resistance to twist.

The higher the compressive loading the higher the lateral, torsional buckling force and the better the H-Beam performs in comparison to an I-Beam.

Looking at the market leaders products is interesting. Pankl for example produce both I-Beam and H-Beam for different applications and I have come to the conclusion that the detailed geometry of an engine and its peak combustion pressures need to be considered to develop the ideal con rod for a specific application.

In the UK many of the aftermarket Con Rod manufacturers have little design capability and use a simple base model and ‘head shrink’ this model to suit a wide range of applications and this doesn’t seem very ideal.

I think that in general most aftermarket rods are likely to be over-designed for the majority of applications and it is only extreme engines that run into trouble and they clealry need a better analysis and design capabilty and buying 'off the shelf' rods is probably a mistake.

[winders]

This thread might be of interest:

Pauter or Carrillo?

My engine builder uses Pauter rods and that is what is in my race engine. He has been building race engines for a very long time. I seem to recall him telling me he has never had a Pauter rod fail.

Scott

[Jimmy18E]

Pauter Rods on two Maxed out 2.5ss 8K + RPM motors, no issues.....

Pauter also has worked my 66mm Crank, oil mods, knifed edged, balanced polished. great folks to work with.

Jimmy

[AlfonsoR]

Originally Posted by chris_seven

In the UK many of the aftermarket Con Rod manufacturers have little design capability and use a simple base model and ‘head shrink’ this model to suit a wide range of applications and this doesn’t seem very ideal.

I think that in general most aftermarket rods are likely to be over-designed for the majority of applications and it is only extreme engines that run into trouble and they clealry need a better analysis and design capabilty and buying 'off the shelf' rods is probably a mistake.

Chris, excellent points.

Many of us get all wound up about "what's the best......?". In the end, the answer "It depends..." is the best answer.

The "best" is to take into account all the variables: engine speed, bore, stroke, rod load, thrust specifications, etc, etc, then base your design on the requirements. If the design is correct, it shouldn't matter what geometry you select.

[Ben M]

Thanks to all for your thoughts and ideas!

[neilca]

Originally Posted by chris_seven

I have been interested in the basic design of con rods for some time and as manufacturers of I-Beam Rods and H-Beam Rods always claim their product is the best it is difficult to make a good judgement.

In general beam theory the difference between the two designs is concerned with the width:height ratios of the two sections.

In an H-Beam the width of the flange is equal to or greater than the height of the cross-section and in the case of the I-Beam the height of the cross-section is greater than the width of the flange.

The strength of a rod in tension is simply a function of cross-sectional area – its shape makes no difference.

The stiffness of the rod in terms of buckling and flexure, however, produces significantly different results and the Second Moment of Area of the section needs to be considered.

For an equal stiffness an H-Beam would be just over twice the weight of an I-Beam. This means that for an equal weight an H beam has only 40% of the stiffness of an I-Beam.

This analysis doesn’t take into account the increased volumes around the big end which reduces weight difference but is does mean that for a given stiffness an I-Beam would be significantly lighter than an H-Beam.

If this were a complete picture then I-Beams would surely be the rod of ‘choice’ and would easily out perform H-Beams and some manufacturers claim that the only advantage of the H-Beam is that it is easier and hence cheaper to manufacture.

The H-Beam shape does, however, have one advantage, and this is in the area of torsional rigidity. It is well understood that a piston will rotate around a cylinder axis and produce torsional loading in the rod.

H-Beams are torsionally rigid in the direction of crankshaft rotation and this does provides some benefit with regard to compressive loading as two wide flat pieces of steel parallel to the plane of rotation provide good resistance to twist.

The higher the compressive loading the higher the lateral, torsional buckling force and the better the H-Beam performs in comparison to an I-Beam.

Looking at the market leaders products is interesting. Pankl for example produce both I-Beam and H-Beam for different applications and I have come to the conclusion that the detailed geometry of an engine and its peak combustion pressures need to be considered to develop the ideal con rod for a specific application.

In the UK many of the aftermarket Con Rod manufacturers have little design capability and use a simple base model and ‘head shrink’ this model to suit a wide range of applications and this doesn’t seem very ideal.

I think that in general most aftermarket rods are likely to be over-designed for the majority of applications and it is only extreme engines that run into trouble and they clealry need a better analysis and design capabilty and buying 'off the shelf' rods is probably a mistake.

I think Chris brings up an interesting question, what is the failure mode you are trying to avoid? Is it tensile, twist or bending. My experiance with rod failures are bolts breaking or bearings starved for oil. I have seen bent rods due to hydrolock or overboast, but that is a rare occasion.

That being said, I like the light weight of an H beam but chose stock rods with ARP bolts for my race engine.

[Steve@Rennsport]

For the record,...

Its VERY VERY rare to see an actual rod failure. The vast majority of rod issues are due to either bolt stretch problems (factory) or mostly bearing related.

Bearing fitment is everything and rod bearing oiling goes hand-in-hand here. Rod bearing quality isn't what it used to be and thats a concern to those building 911 race engines for a living.

Factory rods are plenty strong, they are simply heavy and that places much higher loads on those bearings as RPM's go up. For this reason, lighter aftermarket rods such as Pauter, Carrillo, and Arrow are much preferred for applications where 8K RPM is expected.

[HawgRyder]

A question..
What ever happened to the composite rods from back in the 90's I believe?
I remember seeing an article about them..being made of fiberglass and something...and poured into a mold.
Was that just a pipe dream or did they fail the tests in the end?
I remember thinking that the weight would be of great benefit.
Bob

[TimT]

I remember an effort in the 80's where a plastic engine was developed and used in a Lola racecar. The rods, block, etc. were made of a type of thermoplastic called Torlon

It was 2.3l 4 cyl with a Pinto crank

Plastic automotive engine - Wikipedia, the free encyclopedia


Lola Heritage - History

[chris_seven]

Just before this debat we designed a con rod to suit a 2.0 litre engine and had two sets manufactured. They ahve been installed in engines for a few moths now amd so far so good (to quote the guy who fell off the Empire State Building).

We are now planning for more 2.0 litre engines and as most thisng we try to design we are thinking about trying to refine and enhance the design.

This is the basic model of the lates rod that we have just finished.

Now we will carry out some basic FEA work and see how it looks.

[HawgRyder]

Are these composite rods Chris?
Bob

[chris_seven]

Bob, I wish we were that advanced. they are just steel.

I would like to try some metal matrix composites but tooling costs would be prohibitive. I did some work years ago on the Fracture Toughness and Fatigue behaviour os Aluminium based MMC materials that were being developed for high speed torpedos (125 knots) and they were generally excellent and properties are bound to have moved on.

AMC 225XE for example is around 88ksi and its modulus is similar to Titanium but its density is very low as it has 25% silicon carbide and is based on a good 2000 Series Alloy.

One concern is that its ductility is only around 4% but its fatigue strength is quoted at 340MPa which is no too shabby.


The main problem is that these materials are very difficult to machine so that normally they are forged very closely to a net shape altough some companies do claim to be machining thIs type of material successfully.

I think, however, that it is a bit too much for our recources and I don;t think we will try.


I may try Grade 5 Titanium with a Chromium Nitride PVD Coating as this is much more of a 'known art' situation.

[HawgRyder]

Chris
When I made the front end (Girder type) for my Harley...I used an aluminum alloy called Fortal (I think the spelling is correct) for the stock.
It had better tensile strength than 1020 steel which is what the original girders were made of...and the machined surfaces came out very smooth for polishing.
I kept a cross section on the legs at 1" squared (about twice the steel dimentions) and in the years of riding it has held up nicely.
I just looked it up again...and according to the web...it is 7075-T651 type metal.
I wonder if it...or some of the new 7000 series metals could be used to make rods?
We used to use aluminum rods in the drag engines...but of course they were torn down and rods replaced after almost every run.
Technology marches on...so I have hope.
Bob