Poll: On alternate rod

[blamkin86]

Stupid?? really..
These are opinions of your fellow racers.
I know that if rods are allowed , most new builds will use them. Why?
Turn the crank down to fit new lighter rods, well undersize. reduce the bearing area = go faster.
Now we have crank issues for the 2-3hp that may be the result of the new rod rule.
As an engine builder you have to sell the best engine, so rods are required and the domino engineering that goes with them..

If one or two cars have issues , let them have rods, on stock crank sizes+-025
Will the affected cars go faster, more often?? , yes. Will it affect my car?, maybe.
It is a lot easier to add weight to a car that we made errors on, than refigure the whole class now that we all can rev to intake limits..
Test the water, dont dive over the edge. IMHO.

Well said.

Anyone who thinks rods are reliability only is not thinking about the guy with the money to spend on higher-rpm cam/exhaust/dyno tuning, which could easily be a huge performance advantage. If you grant that advantage to only some of the cars, I'm completely against the rule change.

 

[Ron Bartell]

I agree if you allow rods, you have to allow cranks.

I'm a little slow - it takes me an hour and a half to watch sixty minutes, but could someone tell me why if you allow rods you have to allow alternate cranks as well, or is this to point out that it is inevitable that someone will need cranks because now the rods are not the weakest link.

 

[Sam Moore]

Did I miss something or did the proposal not include the wording to keep DIMENSIONS( I think that would include big end dia. and pin dia.) of the rod stock ?? Sure, given the opportunity I would make the journals AND pins as tiny as possible--there is a clear advantage there!! Like I meant to say--more stupid not stupider. Sorry if I offended anyone out there---just refering to the direction these discussions sometimes go.

 

[blamkin86]

Sam, we're not talking about the 2-3 hp gain from the change in rods.

We're talking about a totally unknown amount of power, gained from changing rods, cams, exhaust, tuning, and whatever else would be possible at the higher RPMs allowed by the alternate rods.

Not all cars are volumetrically limited at their current max (stock-rod limited) RPM. Maybe with enough money, 2.8L Vanos motors can spin to 10K RPM and make 25% more power. I just don't know - and my point is - no one can know.

I do think there's a middle ground here, I just don't know what it is.

 

[Sam Moore]

Stick a fork in me--I am done. Good luck to all. This beaten dead horse will probably not revive unless he can get a dose of Vanos.

 

[Matt Blehm]

Sam, we're not talking about the 2-3 hp gain from the change in rods.

We're talking about a totally unknown amount of power, gained from changing rods, cams, exhaust, tuning, and whatever else would be possible at the higher RPMs allowed by the alternate rods.

Not all cars are volumetrically limited at their current max (stock-rod limited) RPM. Maybe with enough money, 2.8L Vanos motors can spin to 10K RPM and make 25% more power. I just don't know - and my point is - no one can know.

I do think there's a middle ground here, I just don't know what it is.

Then IMO, you cross that bridge when you get there. Currently, the rods are the fuse in the engine, which causes the most catastrophic damage when the fuse goes. and said fuse is a completely unknown length. It could go in one race or ten, and when it goes it takes the rest of the engine with it and will cost several thousand bucks to fix.

If I had to race a car with those probabilities, I'd find another class that allowed me a reliable engine, or I'd find another place to race. I'd rather my friends not scream about a few extra HP so that I could continue to race with them.

If you allow replacement con rods so the engines don't blow and people suddenly start making 50 more HP, then you can restrict those cars with something else- lower compression ratio or valve lift, or more weight.

.... Or you could step up your game and build an engine to beat theirs.. :mrgreen:

 

[JessePrather]

FWIW. The car with the biggest problem with rods in LP form I think might be the FP Miata. If you gave us rods for these engines, we will not rev them higher because at 10:1 compression and .390 valve lift we've already maxed out cams, dyno time, etc. It would only be a reliability issue, not a power issue. I don't know about any other engines out there but we're not limiting our revs because of the rods. The problem exists in the fact that we don't have much of a fudge factor with these stock rods. A couple of missed shifts and you're taking your engine apart to replace inferior rods or you've already scattered your expensive racing engine. Limit the rods to .020 under bearings and everything else stock sizing and you're done. This is really getting overthought in my opinion.

I'm also all for alternate rocker arms with stock ratio's and necked down stainless valves with stock specs. Reliability is the key here, not rules creep with unlimited compression, porting, and valve lift. That's what killed production in the 90's.

Have I said this enough? I think so. See some of you next week!!

 

[RonInSD]

Limit the rods to .020 under bearings and everything else stock sizing and you're done. This is really getting overthought in my opinion.

I'm also all for alternate rocker arms with stock ratio's and necked down stainless valves with stock specs. Reliability is the key here, not rules creep with unlimited compression, porting, and valve lift. That's what killed production in the 90's.

Have I said this enough? I think so. See some of you next week!!

Even with the alternate rods you would be still limited by the current rule 9.1.5.E.2.i.1.

Stock crankshafts are required. The Crankshaft can
be lightened and balanced. Journal diameters can be a
maximum undersize of 0.045 from stock diameter.

Currently the piston pins and bushings are unrestricted so you could run a smaller size pin with the current stock rods. Not sure it would give much of performance increase.

 

[Acme Speed Shop]

Currently the piston pins and bushings are unrestricted so you could run a smaller size pin with the current stock rods. Not sure it would give much of performance increase.

I did just that with my LP MG 1275 rods, used a pin diameter of .750", instead of .812", mostly because it was do-able with a existing pin bushing that required no machine work to the rod, other than honing the bushing to fit the pin, many other have done this as well, which is perfectly legal within the rules. If you were to covert a press fit rod to a floating style, and you're making a custom piston, why not. The only gain is little less weight due to the smaller diameter piston pin, and you gain ease of mantainence being able to easily remove the piston from the rod during refreshing.

Now to address some earlier post, rod journal diameters are already adressed in the rules, if I remember correctly, -.040" is smallest undersize one can legally run. Oh and I keep hearing people state a HP gain with alternate connecting rods that may be lighter, last time I checked, lighter rotating mass does not increase HP. As Jesse stated, the limited factors in LP engine rules is head flow and cams, as long as that doesn't change in the rule, neither does HP, or RPM level, other than thru the development within the current rule set, and alternate rods, or cranks would not play a factor in this. It would interesting to see what sort of weight changes in stock rods, vs alternate there would be in big bore, short stroke engine, I guessing not that much, I remember years ago building a Ford 2300 race engine, the alternate rods were heavier than the stock rods. In the British small bore/long stroke engines, alternate rods are good bit lighter than stock, thru stock prep, you can cut those differences in half, more than half when compared to some of the cheaper alterante rods. The cheaper alternate rods, tend to be a bit heavier than say Carrillo, or Pauter, atleast on the engines I work on.

 

[blamkin86]

As Jesse stated, the limited factors in LP engine rules is head flow and cams, as long as that doesn't change in the rule, neither does HP, or RPM level, other than thru the development within the current rule set, and alternate rods, or cranks would not play a factor in this.

You guys are mistaken. My car is one of the few L2 prod cars allowed alternate rods. I make more power above where the stock rods would not survive. Go ask Jon Brakke how much slower he would be, limited to 8100 RPM.

It's one thing to say the change in rods would not increase power - it's another to say you know you're opening pandora's box and don't care. At least be honest.

That's it for me too. I'm fine with Rods + weight. I'm not fine with just Rods.

Come by spot 434 at the runoffs and say Howdy. And don't take the internet too seriously. :doh:

 

[Acme Speed Shop]

Well, I will continue this debate, I guess , the point being made is a different rod, even if it weighs less , meaning less rotating mass will not increase HP, now if you are saying your alternate rod set allows you to rev to higher rpm limit where your engine is still making more power, ok, but less rotating mass never made more HP, it just lets the engine get to what it already has a bit quicker. it would intresting to see what a short stroke engine rods, stock vs alternate weigh, I bet no where near the difference we see in our long stroke engines.

On the LP engines I've built, MG 1275 and 1800, they make power to certain rpm, which is much lower than that of full prep engine of the same kind do, so if the engine quit making power at say 7500 rpms, then rods that will allow you to rev to, say 8000 rpms, doesn't make you anymore HP and at that point HP is dropping like a grand piano being shoved out of airplane anyway


Maybe, I'm off base, but I don't think there are alot of serious national racers out there turning less rpms, when their engine would still making power in given higher rpm range, and thats why this thread got started, they are breaking rods, and limiting a racer to turn less rpm than his, or her engine makes because the connecting rod might break is kinda goofy. The big limiting factors in LP should be head prep, CR, and cam, those are the things that truely control a given engine's output

 

[Gary Wittman]

I keep seeing posts here that that say less rotating mass does not increase hp. I do know that reducing rotating mass increases acceleration. So, I guess that means it increases torque and will come off the corners faster. I think connecting rods have more reciprocating mass than rotating mass. I also think it does take hp to drive reciprocating mass. Take some weight and move it back and forth as fast as you can, you will realize in a short time how much power it takes to move that weight back and forth. This tells me reducing reciprocating mass frees up some hp. That combined with less rotating mass that frees up some torque should result in slightly faster times on any given track.

I am not trying to make an argument against after market rods. I just don't buy into the "it will not make any more power" argument and think an adjustment needs to be made if lighter after market rods are allowed. That adjustment may be determined to be a small adjustment but should cover the gains by the change in rods be it due to higher rpm capability or just the lighter rotating/reciprocating mass.

 

[Brian Linn]

As Jesse stated, the limited factors in LP engine rules is head flow and cams, as long as that doesn't change in the rule, neither does HP, or RPM level, other than thru the development within the current rule set, and alternate rods, or cranks would not play a factor in this.

You guys are mistaken. My car is one of the few L2 prod cars allowed alternate rods.

Maybe Jesse was only referring to the FP Miata's. I shouldn't speak for him, but that's what I think. Those early LP cars that are in EP are under different rules than most LP cars.

 

[hoffman900]

I agree if you allow rods, you have to allow cranks.

I'm a little slow - it takes me an hour and a half to watch sixty minutes, but could someone tell me why if you allow rods you have to allow alternate cranks as well, or is this to point out that it is inevitable that someone will need cranks because now the rods are not the weakest link.

Lighter connecting rods can mean lighter cranks? More machining on stock cranks can mean more failures? :ask:

 

[Ron Bartell]

I agree if you allow rods, you have to allow cranks.

I'm a little slow - it takes me an hour and a half to watch sixty minutes, but could someone tell me why if you allow rods you have to allow alternate cranks as well, .......

Lighter connecting rods can mean lighter cranks? More machining on stock cranks can mean more failures? :ask:

Thanks for answering but I still don't get it. It is kind of important to understand what is meant here because the poll on alternate cranks does not show the level of acceptance for that rule change and if they are somehow linked we should know it.

 

[loopracing]

Last time we took a poll (2 years ago?) it was exactly 50/50.

 

[RonInSD]

As Jesse stated, the limited factors in LP engine rules is head flow and cams, as long as that doesn't change in the rule, neither does HP, or RPM level, other than thru the development within the current rule set, and alternate rods, or cranks would not play a factor in this.

You guys are mistaken. My car is one of the few L2 prod cars allowed alternate rods. I make more power above where the stock rods would not survive. Go ask Jon Brakke how much slower he would be, limited to 8100 RPM.

It's one thing to say the change in rods would not increase power - it's another to say you know you're opening pandora's box and don't care. At least be honest.

That's it for me too. I'm fine with Rods + weight. I'm not fine with just Rods.

Come by spot 434 at the runoffs and say Howdy. And don't take the internet too seriously. :doh:

What do you think is an acceptable weight increase for the alternate rods? Base + 2.5% or 50 lbs flat across the board?

BTW Bill, I will stop by. I plan on being out there on Tuesday later afternoon to get settled in to enjoy the week. I just hope my cell phone does NOT work....LOL

 

[disquek]

I'm confused.

You're saying that your car has alternate rods. And that the stock rods would not survive into the RPM range where
your motor makes power. So it made sense to give you alternate rods. It was a good decision (assuming you're not an overdog).

Fair enough. But I fail to see the issue with other folks having alternate rods.

If, as it has been said numerous times here, the car in question does not make power above the limit of the stock rods, what's the justification for the weight? It becomes simply a reliability and cost issue then.

If you were pointing out a case where a car didn't have alternate rods and was limited in how much power it made because it didn't have alternate rods, I could see your point.

Maybe I'm missing something.

-Kyle

 

[blamkin86]

Ron - I would assume it'd be some percentage.

Kyle - come by and say hi and we'll talk. Just not before my on-track session please

If, as it has been said numerous times here, the car in question does not make power above the limit of the stock rods, what's the justification for the weight?

Whether it's been said numerous times is irrelevant. If some car suddenly picks up 25 horsepower - who in their right mind would come forward and say "oh yeah, it was the rods. Go ahead and gimme some weight, it's only fair."

Can't put this particular genie back in the bottle.

Essentially, I submit that alt rods will make some cars faster. If you assume we're all equal now, that's not fair.

One alternative would be to take some percentage of weight off the 7-8 cars that already are allowed alt rods. That would probably make everyone happy - as the rods would be optional and not cost anyone weight - and those of us who have that built into their weight would see a break.

Yet another alternative - maybe the best one - is to show some pattern of a particular Level2 car with rod failures, and give that car alt rods. I think that's the best option.

Right now there's a ton of speculation. Point to a car that has - more than one owner, more than one engine builder - clear and obvious rod failure. Fix that car.

Anyway - really - I'm out.

(Edit) Really!

 

[BobC]

Fiat was wise enough to supply the sohc 1500 with forged rods.
It did retain a cast crank - I've been to 9000 many times and 8000 regularly - why the crank suggestion.