Estimated HP gains - bolt on mods and reflash?

[WingsofWar]

Originally Posted by serialk11r

Too many edits. Okay so the area that the wrist pin spreads the forces is much greater, that makes sense. Thanks. I see why it makes sense to use it in frequently rebuilt engines, you can cut down the mass significantly, and the aluminum rod will still survive a respectable amount of time, but if you want to increase the service life the aluminum rod needs significant strengthening which would not be worthwhile.

yep pretty much the jist of it. but your on to something though. We still might see aluminum connecting rods in the future in street cars. I don't believe we have reached the peak of research in rod development.

[serialk11r]

http://www.asminternational.org/cont...81G_Sample.pdf
Interesting read on fatigue. 300M steel seems to have a fatigue limit >4 times higher than aluminum (with 10^8 cycles or so), so in theory 300M rods built to the same strength would be lighter. Damn.
I think for lower rpm street cars the stresses would be low enough and the compressive forces would be comparatively greater so aluminum rods could outlast most of the other engine parts. I think aluminum is probably cheaper than say 300M steel so we might see it in street cars someday.

BTW WoW, the red lettering is quite menacing

[WingsofWar]

Originally Posted by serialk11r

http://www.asminternational.org/cont...81G_Sample.pdf
Interesting read on fatigue. 300M steel seems to have a fatigue limit >4 times higher than aluminum (with 10^8 cycles or so), so in theory 300M rods built to the same strength would be lighter. Damn.
I think for lower rpm street cars the stresses would be low enough and the compressive forces would be comparatively greater so aluminum rods could outlast most of the other engine parts. I think aluminum is probably cheaper than say 300M steel so we might see it in street cars someday.

BTW WoW, the red lettering is quite menacing

lol dont get too intimidated

but ya, big thing about 300M is the amount of increased carbon / silicon over 4340 steel. making it a big costly cluster fuck. Especially compared to aluminum!

In the case of the AS1 as an application, i think Carbon aluminum forged rods would be PERFECT for cost and strength, and performance. because its got a wide rev range, low output non-FI. Making it just as durable as similar 4340 steel in performance engines.

[Dimman]

Originally Posted by serialk11r

http://www.asminternational.org/cont...81G_Sample.pdf
Interesting read on fatigue. 300M steel seems to have a fatigue limit >4 times higher than aluminum (with 10^8 cycles or so), so in theory 300M rods built to the same strength would be lighter. Damn.
I think for lower rpm street cars the stresses would be low enough and the compressive forces would be comparatively greater so aluminum rods could outlast most of the other engine parts. I think aluminum is probably cheaper than say 300M steel so we might see it in street cars someday.

BTW WoW, the red lettering is quite menacing

Serial, if you want to blow your mind on rods, there are currently some dirt-bikes that use an aluminum matrix composite rod. Also it's one-piece and has no bearings.



http://www.ret-monitor.com/articles/...omposite-rods/

Also keep in mind what fatigue is. Repeated loads, over and over again. Then think about how many cycles a con-rod goes through driving over only a half hour. If you look at rods for racing, they are exceptionally well surface-finished as well as fancy metals, and this has to do with fatigue. Any small stress risers will affect the fatigue limit, and then also think of aluminum's relative softness/how easily it will notch on even slight impacts.

And there is also stiffness, (which Old Greg has enlightened be about on numerous occasions) in which aluminum is again inferior to steel. Also why we see the 'H' rather than 'I' pattern cross-section in certain racing rods, more stiffness. In huge HP drag racing where aluminum is most common in rods, the lack of stiffness is actually desirable due to something about how quickly they build power, and the rods bending actually prevents crank failure.

[Homemade WRX]

Originally Posted by serialk11r

Too many edits. Okay so the area that the wrist pin spreads the forces is much greater, that makes sense. Thanks. I see why it makes sense to use it in frequently rebuilt engines, you can cut down the mass significantly, and the aluminum rod will still survive a respectable amount of time, but if you want to increase the service life the aluminum rod needs significant strengthening which would not be worthwhile.

you've got the idea now. Also keep in mind that pistons are usually 2618 and they have a higher strength 'at temp' than 7075. But now you get the idea of the load area for the forces perpendicular to the crank axis (up and down). The big force that usually causes rods to fail (neck before bending) is pulling away from TDC on the intake stroke. It then folds on the following combustion if it doesn't actually tear through. In this case, the rod is now fighting the momentum that the piston had when approaching TDC on the exhaust stroke.

Edit: forgot to mention that you'd probably run into fitment issues with an aluminum rod in an FA case if building for lower power but longevity. I couldn't get them to fit without extensive case clearing for EJ applications.

Originally Posted by serialk11r

http://www.asminternational.org/cont...81G_Sample.pdf
Interesting read on fatigue. 300M steel seems to have a fatigue limit >4 times higher than aluminum (with 10^8 cycles or so), so in theory 300M rods built to the same strength would be lighter. Damn.

Yup
billet 4340 rods are my budget rods and 300M are a $180 add on. L19 bolts standard and then I upgrade to 625 for my guys going after 4 digits.

Originally Posted by Dimman

Serial, if you want to blow your mind on rods, there are currently some dirt-bikes that use an aluminum matrix composite rod. Also it's one-piece and has no bearings.

Perhaps I ought to bite my tongue on this but what fun would that be?!

My mind isn't blown...though I will say that rods are next on the list once piston testing starts in two months.

[Mr.Jay]

^ cant wait for group buy

[Homemade WRX]

I do plan to toss MMC pistons in and will probably start with A-beam 300M rods for customers running the FA engine while the MMC rods are going through testing.

**Because of volume, the MMC rod development will probably be done under my EJ race engine program.


and I think we are well beyond 'bolt-ons' at this point

[serialk11r]

Can you quantify the amount of mass that can be trimmed off pistons/rods/(anything else I missed that people swap out?)? And would you happen to know what effect this has on friction? (I read that piston rings, piston skirts, and rod bearings are about 40% of overall engine friction, and that piston rings make up a big portion of that...so not expecting much)

Also can someone share with me the effect of reciprocating mass on response and acceleration...reciprocating mass hits 0 velocity at top and bottom of stroke but the increased peak velocity as speed increases should have an effect right? Something I haven't thought much about.

[WingsofWar]

Originally Posted by serialk11r

Can you quantify the amount of mass that can be trimmed off pistons/rods/(anything else I missed that people swap out?)? And would you happen to know what effect this has on friction? (I read that piston rings, piston skirts, and rod bearings are about 40% of overall engine friction, and that piston rings make up a big portion of that...so not expecting much)

Also can someone share with me the effect of reciprocating mass on response and acceleration...reciprocating mass hits 0 velocity at top and bottom of stroke but the increased peak velocity as speed increases should have an effect right? Something I haven't thought much about.

oh man, i wish i could answer that..i kinda have an idea..but i don't think im good at explaining it. I should ask my uncle, hes an engineer that builds aircraft engines for boeing and builds Hydroplane engines for a hobby. Fucking smart ass people in this world, makes me feel like an idiot sometimes. Homemade WRX has got this in the bag, especially if hes got plenty of crazy EJ builds under his resume.

[serialk11r]

Okay I thought of some stuff. So the reciprocating mass' kinetic energy is more or less recovered (minus friction) when the velocity hits 0 at TDC/BDC. However at the peak velocity it has some amount of kinetic energy. I think the effect on acceleration would be the average kinetic energy stored, but this seems wrong in some way...since the net is 0. If we assume sinusoidal motion and that the pistons actually store some energy (which is bad but not that far off) then it would be pi/4 times peak kinetic energy, which is very significant.

What I'm getting is that it doesn't actually affect transient response or acceleration much because the reciprocating motion is effectively smoothed out by rotational inertia. The effect on acceleration would be very minimal, since the reciprocating motion absorbs energy from and puts energy into the rotating motion. Sounds pretty crazy, but it makes sense. Although heavier pistons and rods would increase vibrations and have a noticable impact on smoothness, which manufacturers seem to solve by using heavier flywheel.

So another question remains, how much do lighter internals reduce friction as a proportion of total friction? I read some paper yesterday that showed something like 1% overall friction reductions with smaller journals alone, which suggests actually reducing bearing loads would do more. Loads increase as a 2nd degree polynomial function of engine speed +the constant effect of cylinder pressure assuming the typical linear relation between normal force and frictional force, lighter mass would be responsible for a similar decrease in the coefficient of the x^2 term, except that half the time the cylinder is exerting an opposite force so that makes things a bit complicated, doh. From typical FMEP vs. rpm graphs it's pretty hard to tell what proportion of the load is non-linear...if there were no cylinder pressure then it would be a straight line, but there is something complicating it. help?

EDIT: Actually I guess loss to oil pump and such would explain the "higher degree" losses. Bearing friction seems to account for about 20% of overall friction (more if water pump is electric), and piston skirt friction would go down a little bit so 25% seems like a safe guess. If reciprocating mass is reduced 20% then overall engine friction would go down about 5%. If engine friction is worth 10% of engine power/torque at full load, then this would be a 0.5% increase in efficiency. If friction is 20%, this is a 1% increase. How does this compare to real data or better models? Oh and of course, how much weight can you trim using 300M rods

[Dimman]

Originally Posted by Homemade WRX

I do plan to toss MMC pistons in and will probably start with A-beam 300M rods for customers running the FA engine while the MMC rods are going through testing.

**Because of volume, the MMC rod development will probably be done under my EJ race engine program.


and I think we are well beyond 'bolt-ons' at this point

What? This isn't my 'Engine Tech' thread? Dammit...

Have they got to the point where they can economically machine MMC for a 2 piece rod? Article says they are mostly net-shaped forged, with a fancy high-speed boring operation, since the matrix is aluminum and silicon carbide. And silicon carbine is usually on the side doing the machining operation rather than the receiving end.

Also what is the cost difference between normal 4340 and 4340M/300M?

[Homemade WRX]

Originally Posted by serialk11r

Can you quantify the amount of mass that can be trimmed off pistons/rods/(anything else I missed that people swap out?)? And would you happen to know what effect this has on friction? (I read that piston rings, piston skirts, and rod bearings are about 40% of overall engine friction, and that piston rings make up a big portion of that...so not expecting much)

Also can someone share with me the effect of reciprocating mass on response and acceleration...reciprocating mass hits 0 velocity at top and bottom of stroke but the increased peak velocity as speed increases should have an effect right? Something I haven't thought much about.

I'll get to the other post, when I have time to sit down and run through it.

As for the frictional losses; it'll depend on the engine as to how much friction is where. For instance, push rod vs. SOHC vs. DOHC. Is the DOHC work on a rocker (hydro or not?) or is it a bucket style?...rod ratio, bore stroke ratio, bore size, ring design, etc...all are factors. Timing belt/chain designs play a roll. This is why I wouldn't both trying to guesstimate what is what. Of all of this the only thing that I can really change is the shortblock, as getting into reworking timing components and making a custom head is a big job and a lot of money.

As for reciprocating mass, think of it from square one. What makes the crank turn? Combustion in one chamber. What does this have to overcome? For a 4-cyilnder (easy to think of a 4-stroke) you then have to overcome the forces of one cylinder going through exhaust stroke (pressure), one on intake stroke (slight vacuum or negative pressure) and one that is compressing the intake charge (more pressure). Now beyond that, you also have the frictional losses of each cycle (as friction will vary from load of each of the four strokes). Now also think of the energy used to turn all of the reciprocating mass as it does require energy to accelerate it.

Neglecting the mass as purely mass would be much like assuming that picking up 200 lbs is just as easy as 100 lbs...but now an engine is much more complex than that simple example. Perhaps saying catching a 20 lb pound medicine ball and throwing it back compared to doing the same with a 10lb medicine ball. You have to catch it and then throw it back...accelerating in two directions.

Originally Posted by Dimman

What? This isn't my 'Engine Tech' thread? Dammit...

Have they got to the point where they can economically machine MMC for a 2 piece rod? Article says they are mostly net-shaped forged, with a fancy high-speed boring operation, since the matrix is aluminum and silicon carbide. And silicon carbine is usually on the side doing the machining operation rather than the receiving end.

Also what is the cost difference between normal 4340 and 4340M/300M?

We aren't working on pricing on rods, yet. It is planned down the road and pricing will be brought up as it plays a big role in the aftermarket industry. However with the pricing on pistons, we are trying to keep it down and rather market competitive to others out there.

[Dimman]

^ I was thinking of the material specifically. Curious about the 'M' 4340. Since it's only a few alloying elements different than 'normal' 4340, I wouldn't think it would too different price-wise.

But then I'm thinking that if the effort is made to modify 4340 for superior properties it is also likely that it will be made with higher-purity (vacuum re-melt) and therefor more expensive manufacturing processes?

[Homemade WRX]

Originally Posted by Dimman

^ I was thinking of the material specifically. Curious about the 'M' 4340. Since it's only a few alloying elements different than 'normal' 4340, I wouldn't think it would too different price-wise.

But then I'm thinking that if the effort is made to modify 4340 for superior properties it is also likely that it will be made with higher-purity (vacuum re-melt) and therefor more expensive manufacturing processes?

Well condsidering my rods are VAR anyway, that wouldn't be a cost increase. I am vaguely familiar with 4340M but if I recall it actually doesn't contain any elements different from 4340 but lacks a few that 4340 has. I believe it has a higher molydenum percentage as well. So, I'd guess a harder material = more machine cost.

Sorry, I don't really know your answer off the cuff. I guess I'm off to see what I can find on it's properties versus 4340 and 300M. Where I imagine it will fall in cost. But if that's the issue, the $160 difference between 4340 and 300M, I don't think there will be market there...from a part making perspective.