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Should Prep 2/Limited Prep engines allowed alt rods
Yes 63%  63%  [ 51 ]
No 37%  37%  [ 30 ]
Total votes : 81
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 Post subject: Re: Poll: On alternate rod
PostPosted: Wed Sep 12, 2012 2:31 pm 
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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

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 Post subject: Re: Poll: On alternate rod
PostPosted: Wed Sep 12, 2012 2:57 pm 
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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.

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 Post subject: Re: Poll: On alternate rod
PostPosted: Wed Sep 12, 2012 5:23 pm 
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blamkin86 wrote:
Acme Speed Shop wrote:
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.


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 Post subject: Re: Poll: On alternate rod
PostPosted: Wed Sep 12, 2012 5:40 pm 
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Location: South Jersey
Ron Bartell wrote:
Aaron Johnson wrote:
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:

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 Post subject: Re: Poll: On alternate rod
PostPosted: Wed Sep 12, 2012 7:19 pm 
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hoffman900 wrote:
Ron Bartell wrote:
Aaron Johnson wrote:
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.

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 Post subject: Re: Poll: On alternate rod
PostPosted: Wed Sep 12, 2012 8:13 pm 
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Last time we took a poll (2 years ago?) it was exactly 50/50.

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 Post subject: Re: Poll: On alternate rod
PostPosted: Thu Sep 13, 2012 11:17 am 
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blamkin86 wrote:
Acme Speed Shop wrote:
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

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 Post subject: Re: Poll: On alternate rod
PostPosted: Thu Sep 13, 2012 12:10 pm 
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Joined: Fri Nov 06, 2009 7:08 am
Posts: 700
Location: Philly
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


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 Post subject: Re: Poll: On alternate rod
PostPosted: Thu Sep 13, 2012 1:11 pm 
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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 :)

disquek wrote:
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!


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 Post subject: Re: Poll: On alternate rod
PostPosted: Thu Sep 13, 2012 9:32 pm 
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Location: Pueblo West, CO
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.

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