wanted 155mm rifle drilled rods

[URQguy]

Jamo, I am calm my friend. A guy gets a b5 Rs4 and he is already picking up the b5 attitude When you say "better", you imply one route is higher performance than another. That just isn't the case. It is an alternative, and frankly a budget friendly one when considering the cost of custom pistons, but it is by no means "better".

Which piston would you want rotating at 8500 rpm at a mean speed of 27m/s?




That is an AAN pistons with a broken ringland btw on E85 with zero detonation at 630whp/550wtq. I have seen them break on a couple engines at that output on exotic fuels

[kamuto]

Jamo, I am calm my friend. A guy gets a b5 Rs4 and he is already picking up the b5 attitude When you say "better", you imply one route is higher performance than another. That just isn't the case. It is an alternative, and frankly a budget friendly one when considering the cost of custom pistons, but it is by no means "better".

Which piston would you want rotating at 8500 rpm at a mean speed of 27m/s?



That is an AAN pistons with a broken ringland btw on E85 with zero detonation at 630whp/550wtq. I have seen them break on a couple engines at that output on exotic fuels

first of all you need know how to tune e85 I know a car which are having 900hp with stock aan pistons.. there is one thing called MBT Minimum Best Timing, thats like you are geting max power ant 20 degres, you are over advancing it more like 25 28 degrees, very low gain of power, 0 knock and engine will fail.

[URQguy]

Hp isn't going to break ring lands, torque is. That said 900hp is close to 635whp using a 25% drivetrain loss on a mustang dyno. The day this car broke that ringland, there were 3 b7 rs4s that made inbetween 280-302whp on teh same dyno. Furthermore, 2.7tt motors that use mahle forgings as well, with very similar geometry of ring packets also start breaking ringlands at 175ft/lbs per piston. The guys breaking stock pistons on 2.7tt have similar turbo setups(light GT turbos with billet wheels like the TiAL 770 kits). The cars we are seeing break aan pistons are light billet HTA3582r turbos flowing 75lbs/min with full boost by 3900 rpm, boosting 35-40psi at torque peak.

You could calibrate boost control to save stock pistons i suppose by limiting torque in the lower rpm range, but that is just lowering the torque output of the engine.

I am familiar with e85 and did my college thesis on the topic. Spent over 200 hours on a dyno mapping thermal efficiency of a turbo 250cc from 0-100% methanol and ethanol content with cylinder pressure probe.



I realize that individual cylinder EGT logging and wideband sensing is a way to derive CP(and theus mbt) via the ideal gas model, but the engine was properly calibrated.

[Billman]

I used Sten Parner rods with 158mm length and 23mm Pins. At the time of purchase I did not want to go I-Beam with Pauter (they where not offering H-Beam) so went with that.

[quattro84]

Forum wisdom and big mouths,

H-beam has greater resistance to buckling compared to Pauter anytime pound for pound, so i don't get the fuss about the holy Pauters these days...

Everyone who has followed the basics of engineering knows that the Second area moment of Inertia for H-sized cross sections is much higher than "+" sized part.



Diagram of stiffness of a simple square beam (A) and universal beam (B). The universal beam flange sections are three times further apart than the solid beam's upper and lower halves. The second moment of inertia of the universal beam is nine times that of the square beam of equal cross section (universal beam web ignored for simplification)


Longer rods are always more efficient when it comes to transferring energy, reducing piston wall friction losses, buckling effects on the conrod, ...

I don't care which rod is the best, one thing i do know for sure is that Pauter's design is not the best available in engineering terms.

[diesel des]

This is getting interesting... Urq guy, what rods and pin size were you using untill the failure? Rifle drilled?

What's people's thoughts on 9a pistons 82.5mm forged. Do they have enough meat on them for long term use. I don't want to build a weekend hero, 800hp car, but something that will do 500 maybe 600 hp all day for a fair few tens of thousand miles.

[campbellWS]

Forum wisdom and big mouths,

H-beam has greater resistance to buckling compared to Pauter anytime pound for pound, so i don't get the fuss about the holy Pauters these days...

Everyone who has followed the basics of engineering knows that the Second area moment of Inertia for H-sized cross sections is much higher than "+" sized part.



Diagram of stiffness of a simple square beam (A) and universal beam (B). The universal beam flange sections are three times further apart than the solid beam's upper and lower halves. The second moment of inertia of the universal beam is nine times that of the square beam of equal cross section (universal beam web ignored for simplification)


Longer rods are always more efficient when it comes to transferring energy, reducing piston wall friction losses, buckling effects on the conrod, ...

I don't care which rod is the best, one thing i do know for sure is that Pauter's design is not the best available in engineering terms.

I can appreciate the engineering point of view as I dont know much myself, tho i thought the x-beam design, particulary the pauters have more material joining the two ends???????

I think the end machining quality of the pauter rods are a big selling point for most folk, the end product shows.

do you know of any other rod manufacturer that uses as traceable material as pauter?
what rods do you think are higher quality than pauters?

[quattro84]

I'm not ranting about quality nor material specs of the Pauters (that is fine for what i have seen of it) it's the design/shape of the final product.

The shape is not ideal for what it's main purpose is, transferring energy in form of force.
The amount of material at the center does not make it better, it needs to be at the outer edges to make it stiffer -> look at the supports of any roof for instance, wooden support beams are in the upright position for a reason.

Think of a ruler when applying a buckling/bending force in the laying position compared to the upright postion. Same material/weight, but very different stiffness due to geometric shape -> moment of inertia!

So, theoretically, an H-pattern product could be engineered with less material (=mass) for equal stiffness compared to the +-shaped product.

[Billman]

what rods do you think are higher quality than pauters?

Pankl if you have the money....

Maybe Carillo (Same Family with CP-Pistons now and all of them under Pankl Group).

[URQguy]

This is getting interesting... Urq guy, what rods and pin size were you using untill the failure? Rifle drilled?

What's people's thoughts on 9a pistons 82.5mm forged. Do they have enough meat on them for long term use. I don't want to build a weekend hero, 800hp car, but something that will do 500 maybe 600 hp all day for a fair few tens of thousand miles.

I used Scat rods in my Tall deck motor I built 2 years ago before I had developed my own 160x20mm rod that drops in with 9a pistons. These 20mm pined ABA rods SCAT makes have very thin necks. They rate them at 175ft/lbs per rod, and I am pretty sure I just exceeded that figure. Again, 42psi with an HTA3586r available at 4000rpm on a 10:1 CR motor makes for a bit of torque. I made 635wtq@ 4550 rpm at 38psi. My guess is that at 42psi, I was making close to 660wtq. I couldn't hold 42psi past 6000 rpm and would taper to 32ish by 8500, but the damaging torque was had pretty low. I had been running at 38psi for the better part of 6 months without issue, but I wanted to get it on the dyno one last time before I swapped it into my CQ in preparation for an 07k 5 cylinder.

Bearings were find on the other cylinders, crank looked surprisingly great. No signs of oil starvation despite not being rifle drilled.

here is a picture of the whimpy Scats compared to my 144mm I beams.



I wish I had a picture of them next to my 160 rod, but they are substantially smaller necks.

The reason we developed the 160 rod is that a tall deck ends up being aroudn 236.75mm, coupled with an MLS 1.6mm headgasket allows for these rods to drop in with cheap off the shelf 9a pistons for an affordable tall deck config without custom pistons.

Quattro87 is indeed correct about pound for pound strength. Most race cars use ibeams for windage gains. An H beam is terrible for scooping up oil in the pocket and flinging it against the wall. If you look at our Ibeams, you can see we left the long part of the inside cross section pretty stout to help with buckling in the y direction, while keeping the Top and bottom stout to minimize x deflection.

They are heavier than the H beams by about 10% but we recover that weight in strength by close to the same amount. To make an equivalent hbeam, you would have to machine the blocks at the bottom of the cylinder.

I agree with most everything quattro84 only critic is that the term "ibeam" has been pretty generalized in your post.

[JP]

I've personally always had a liking to pauter x-beam for strength. They weigh more than a h beam however they are indirectly stronger.

This is because a rod needs to act under tension aswell as compression. And unfortunately I have seen it happen before more than once when engines running high boost and compression ratios seperate the small end of the rod away from the main body on throttle lift of on a h-beam design.

Now I have also had first hand experience with a 1.8t running 2bar boost 500+hp during mapping they added a 150shot of nitrous forgetting to switch the secondary fuel pump on. The result was an almighty bang. Spark plug out the side of the head straight through the tensioner and car inner wing.

Head was a write of. The je piston was molten away on cyl 1. The factory crank had bowed 7thou, the lower half of the bore on 1 had ovalled by 6thou starting to crack.

The rods which were pauter measured up true on length, big end and small end bore with no deflection on all 4 rods. Ao they were used again and still going strong 7yrs later.

I'm sure there is better designs out there but whatever pauter does they have always done right for me never having had a failure unlike the more commonly favoured h-beams.

As for the new I-beams that are doing the rounds I've not used them before so can't comment on them. As it doesn't matter what maths you work out on paper the forces not accounted for in real life situations will always find weaknesses.

[quattro84]

I was keeping the I-beam out of the discussion for understandability purposes only, ultimately the "best" stiffness/weight/aero shape/efficient ratio will be a combination of but H and I shape with material at the places where it's needed, something those ExtremeTuners from Greece end up with:


Since such a shape would involve extra machining after forging the total costs for such a product do not add up for the applications we use them for (IMHO)

On another path, what pin desaxation do you use?

[quattro84]

As it doesn't matter what maths you work out on paper the forces not accounted for in real life situations will always find weaknesses.

I respect your opinion and achievements, but this is a dodgy statement. There is no such thing as unaccounted real-life forces.
Anything can and will be accounted for in modelling. (BTDT)

I calibrate heavy duty engines for a living pushing 3500Nm (with rods of 260mm between pin centerlines hanging on 550gr piston incl 50mm wristpins) and these do not fail/buckle on any engine failure except hydro locking so not that strange that a Pauter (sure a H- or I-beam will do the same) survived such a blow.

I am going to quit my part in this discussion /although mighty interesting/ since the main topic for TS was not: How to design my own rods.

[JP]

True true, bit of a broad statement. What i shouldve said is, as a general rule of thumb I feel most things out there being used in the automotive industry are used because the end consumer takes it for granted that when the original r&d was done it was done correctly. Although real life experience leads me to believe that not all eventualities have been correctly modelled prior to certain products becoming available to end consumer.

As for those rods pictured overkill to the extreme but just for that reason would love to have some

[bernsaudi]

Jeez we are not worthy..
I'm going to gas my s2 Des!