LP Connecting Rod Discussion

[Ron Bartell]

Any British car should be allowed good rods. The Honda, VW all have forged rods , OE.
The British cars should be allowed anything inside the engine as long as it breathes through the legal ports, cam and head/carbs. No reason for anything else ,logically. .
Tech should not even pul the pan for them, head, carb, cam cc. done,( maybe allof the cars.??)

Even the Briggs- kart clubs allowed good rods when the factory ones tossed. Blown up engines cost us all money , not just the owner. No shows, poor racing etc.
Write the paper . I''l sign yours and write another .
MM

Maybe it is time to take another bite of the apple on this rod issue. Keith blames the CRB for messing this up and not allowing aftermarket rods, but in fact IIRC they put the question out to the membership and got around a 50/50 response that weighed slightly on the side of not allowing the rods so it didn't pass.

I was not in favor of allowing them because unlike some of the modern cars they are very expensive for our old British stuff, so with two motors I was looking at over two grand for something that I didn't think we needed on an LP car because the revs are low. Also, I was concerned that if the modern cars got rods they could rev them even higher than they already were, and at the time they already had a huge advantage on the LBC's.

Since that time I have blown an engine due to a poorly prepped rod (not mine, but a very costly mistake), and I have learned that the stock rods on these modern cars are already good enough to allow them to rev to the limit of their breathing capability anyway. This is a huge turnaround in awareness for me, and I would now be in favor of allowing them for the LP motors.

Not saying that my opinion means anything more than anyone elses, but I was quoted at the time as saying that if I don't think they are needed, they aren't needed. Well, the facts say otherwise and we should revisit this issue.

 

[Ron Bartell]

I should point out that I am OK with the rules as written. However when I hear that Keith can't keep his motors together because of breaking rods, I have to wonder what is going on. Since the Toyota should have relatively modern rods, why are they breaking? Are they being lightened too much? Is the motor being overreved? What is going on that would cause the rod issue to be one that causes such grief towards the club management?

 

[zChris]

Ron, I would start by saying that H-beam rods are not expensive. In fact, usually cheaper than stock prepped rods if you know where to look. Eagle/Scat quality rods are available in any size for about $325 a set when bought 12 rods at a time. Modern engines have problems because most modern engines are built with uber light rods to help with fuel mileage. Hence there is little extra strength for anything more than stock HP and RPM. I left the Prod group after a rod failure and not getting anywhere on my request for a change. Its just to damn expensive when you lose a motor. And it offers no HP or torque gain. It just makes racing more affordable to not use stock rods. I'm building a GT car now. I will not have to worry about rod failures again. It didn't help that the person guiding the rule last time makes money prepping stock rods. Kind of a conflict of interest. But thats a whole other discussion.
Chris

 

[loopracing]

When the survey was given last time, it turned out to be almost exactly 50/50. I believe mostly british car guys were against it.

 

[Al Seim]

I voted "no" and will explain. I'm also willing to reconsider based on thoughtful input from others.

1. Rules creep - I left Prod once largely because I felt that "full prep" cars - especially the engines - had gotten beyond my interest in terms of radical modification / expense / poor reliability. And full prep did indeed proceed from near stock one well intentioned rule liberalization at a time, so that causes me to be prejudiced against liberalization of the limited prep rules.

2. Perceived barrier to entry - this may be hard to explain, but I've always felt that the longer the list of approved mods, even ones that might not make the car more competitive, the more likely a prospective entrant/car builder is to say "sheesh, I can't afford to build one of those, they have race rods, dry sumps, carbon fiber johnson bars etc".

3. Unintended consequences - although race rods won't make my VW any faster, as a set of minimally prepped rods will allow the engine to spin past its breathing limits anyway, I'd bet that there are a few cars out there that will suddenly go faster as a better set of rods lets the engine spin faster..... And then (being a bit cynical and doubting that those cars will be slowed down) either they win too much or maybe worse everybody lobbies for and slowly gets various allowances to speed them up.

 

[Al Seim]

Continued since my PC / browser seems to hate letting me make long posts:

4. Stability - Prod (and most race classes I think) seems to net suffer the more changes are made. Moving goalposts are discouraging to low budget, time limited hobby racers.

I think that all these reasons are reasonable and valid. There is however one big counterpoint that maybe should win:

To me, the biggest single "good thing" about the Limited Prep ruleset is that - in general anyway - the engines are breathing limited wrt RPM, rather than mechanically limited. In other words I shift my VW at ~7200 in order to go faster, rather than to avoid expensive exploding noises. (I heard too many of those way back when in my Datsun 1600 GP car, which would have made great power well into the 8000s if I could have kept it together.....As I found, even with guidance from great folks like Joe Hauser, it was terribly difficult for a budget racer to self-develop a mechanically limited engine.)

If a car is mechanically limited by weak conrods, that removes this "good thing" from their car and maybe to the detriment of the Prod category. Though of course it likely raises my point #3 above.

Al Seim
HP Scirocco 1.6

 

[Tom Broring]

Ron, since I have already invested in prepped stock rods, I have reason to say others should do the same. If I step back from my personal benefit I would say I have no problem with them being allowed on a spec line, such as Keith's Toyota if he can argue that is a weak link. I would say that if we open the door to them all the way there should be a weight penalty if someone chooses to run them on a limited prep Level 2 engine.

For my Spitfire, aftermarket rods are costly. I have not seen issues with prepped stock rods running the mild compression and reletively low RPM I see in HP. The benefit for me would be less weight (aftermarket rods are always lighter) which would both help performance slightly and help the 3 main crank live longer. In addition, the aftermarket rods have less metal and surface area for oil to cling to and to pass through the windage area. Although I have no numbers, I think both these benefits would add up to a couple hp. NASA currently uses weight penalties for certain optional mods and this appears a sensible approach for amature racing. Thay way if someone chooses not to upgrade they are not necessarily going to loose out. If the rods only helped reliability I would think no penalty would apply.

If this would be allowed only on certain spec lines I would let the prod advisers decide if a performace advantage applies and if that may be warranted for that car.

 

[zChris]

aftermarket rods are costly

Tom, I'm guessing you did not read my post above.

The benefit for me would be less weight (aftermarket rods are always lighter) which would both help performance

A stock miata rod and a Eagle H beam weeigh within 2 grams of each other.
Chris

 

[Keith Church]

Ron,
I don't lighten the rods at all. Assembly is balanced with the crank. Have tried everything but anytime I make over 9.5 to 1 compression the rods break. Have lost rods that were only sized as well as rods that were sized, cryo'd, rem'd etc. Ask Russ Theus, Scott Fritchley, Janet Guthrey or anyone else who ran these and they will all tell you step 1 is get forged rods. Wouldn't bother me if I hadn't started with full prep G motor with forged Eagles that never broke. The assertion that rods make either power or revs is absolute BS and any decent engine builder would never make that statement. Cast is cast, nodular iron has its weakness else they would never have needed forges. Do you mean to imply that blowing up engines is our sanction body's idea of equalizing competition? Rules creep should apply to rules that improve performance via increased horsepower or rev range. Replacing rods with stronger rods of equal or greater weight does not improve horsepower or rev range. Induction or compression changes must be made to enhance performance, period.

I have posted this in the Rules thread. Maybe someone can move some of the other post there.
Thanks,
Keith

 

[Al Seim]

The assertion that rods make either power or revs is absolute BS and any decent engine builder would never make that statement. Cast is cast, nodular iron has its weakness else they would never have needed forges. Do you mean to imply that blowing up engines is our sanction body's idea of equalizing competition? Rules creep should apply to rules that improve performance via increased horsepower or rev range. Replacing rods with stronger rods of equal or greater weight does not improve horsepower or rev range. Induction or compression changes must be made to enhance performance, period.

In a word - wrong.

If you've got an engine that can breathe well enough to make max power at 8000 RPM and you can't rev it past 7000 for fear of breaking the rods, then the rods just cost you power. Indirectly, maybe, but a power loss nonetheless. Seems pretty simple and obvious to me.

And - many items making up "rules creep" were surely sworn by the requestor to not make performance.

Not to say that you shouldn't get your non OEM rods, I half think you should, just can't agree with calling "BS" that replacing rods could possibly make a car faster.

 

[zChris]

If you've got an engine that can breathe well enough to make max power at 8000 RPM and you can't rev it past 7000 for fear of breaking the rods, then the rods just cost you power

So Al, let me get this straight, you believe that everyone should blow up one or two engines to verify what the working limits of a part are, and then tune the cam ect... around this weakness. OK Glad I bailed on Prod.
Chris

 

[Gary Wittman]

Keith, you have stated that you can't get over 9.5/1 compression without breaking. You have not stated what rpm you are running at. I know a bending moment can occur with higher compression but it seems the main killer of rods is the tension/stretch they see at higher rpm, be it on the rod itself or the rod bolts. Compression tends to kill bearings before rods.

I thought the original idea in allowing the LP engines was to allow larger displacement but keep them near stock so they would not become over-dogs. Utilizing stock rods is a way to limit the rpm. All engines have a rpm limit for one reason or another and the builder should know what that is. If you can show that you are running limited rpm and are still breaking rods due to compression alone, then allowing after market rods for your engine may be needed. I think opening up after-market rods to everyone is asking for trouble.

It has been shown that after-market rods can be reasonable in cost but that is not true for all engines. I have run stock rods in my full prep engine since I started racing in 86. I could not afford after-market rods and still can't. I take them to 8,000 rpm all the time and will go to 8,200 if I need to. I have over revved on mis-shifts and the tach memory tells me it has gone over 10,000 one time and in the 9,000 range several times. Resizing the big end is required at rebuild but I have been running the same two sets of rods from the beginning (with the exception of a few rods that had spun bearing early in my racing career). Rod bolts get replaced periodically.

 

[harvey]

I am all about the rules creep thing but in the case of the LP Prod cars that horse has not only been let out of the barn but it is already in another county. The other thing is NO BODY is telling you that you HAVE to use aftermarket rods.

 

[peterzekert]

Keith,
Call (three-one-four) 724-7098.
Peter

 

[Al Seim]

If you've got an engine that can breathe well enough to make max power at 8000 RPM and you can't rev it past 7000 for fear of breaking the rods, then the rods just cost you power

So Al, let me get this straight, you believe that everyone should blow up one or two engines to verify what the working limits of a part are, and then tune the cam ect... around this weakness. OK Glad I bailed on Prod.
Chris

I said that???

:roll:

And what you incorrectly think I believe chased you out of Prod???

Sheesh, people, be reasonable. It's quite a stretch going from me stating that improved rods CAN in some cases increase power - which they obviously can if they increase the mechanical ability to rev in an engine that can make power at higher revs - to accusing me of hoping your engines blow up. It's sad that a person can't lay out both sides of an argument without being attacked for not supporting one side or the other.

 

[zChris]

I will say this only once, and then I'm done with this thread. You limit performance with weight, inlet restriction, cam lift and or duration and compression ratio. Not with engine parts that will cause season ending problems. That is just STUPID, STUPID, STUPID. Is that plain enough. And yes, this is just IMHO.
Chris

 

[Dayle Frame]

I am all about the rules creep thing but in the case of the LP Prod cars that horse has not only been let out of the barn but it is already in another county. The other thing is NO BODY is telling you that you HAVE to use aftermarket rods.

Yes, but you now how this game is played. If I want to be competitive, I have to keep up with the pack. Carillos will make the motor spin better. It won't add reliability as a BMC A motor's rods are plenty strong. I've never had an issue and I've zinged it a few times to over 8800.

I was against the idea of after market rods in the past and I still am. Part of choosing the car you want to run is it's liabilities as well as its strengths. My car has some great strengths. It has awesome brakes and handles pretty well. And since I don't have a roof, this fat ass can get out of it pretty easily. :wink: But I have one helluva liability......it's motor is 300 or 400 cc's smaller than some I race against. At any track other than RAm, i have a pretty good package to compete (the driver sux but the package can compete). Again, you have to look at the whole package.

I agree that the LP horse is galloping away from us. But this is one place we can say "no" to rules creep.

Dayle

 

[harvey]

I am all about the rules creep thing but in the case of the LP Prod cars that horse has not only been let out of the barn but it is already in another county. The other thing is NO BODY is telling you that you HAVE to use aftermarket rods.

Yes, but you now how this game is played. If I want to be competitive, I have to keep up with the pack. Carillos will make the motor spin better. It won't add reliability as a BMC A motor's rods are plenty strong. I've never had an issue and I've zinged it a few times to over 8800.

I was against the idea of after market rods in the past and I still am. Part of choosing the car you want to run is it's liabilities as well as its strengths. My car has some great strengths. It has awesome brakes and handles pretty well. And since I don't have a roof, this fat ass can get out of it pretty easily. :wink: But I have one helluva liability......it's motor is 300 or 400 cc's smaller than some I race against. At any track other than RAm, i have a pretty good package to compete (the driver sux but the package can compete). Again, you have to look at the whole package.

I agree that the LP horse is galloping away from us. But this is one place we can say "no" to rules creep.

Dayle

I agree with your concept but have to agree with Chris on this 1 it is just plain STUPID to have something like rods that in a lot of cases are 3 to 4 times the expense of aftermarket be the limiting thing that DESTROYS a engine especially considering there are already LP Prod cars that CAN run aftermarket rods.

I think that you are unfortunately looking at this with blinders on just like So MANY things that the SCCA is doing in general. I will have to admit I did it in the past but am trying my best to broaden my scope a little.

 

[Ron Bartell]

Facts:
1) It is a very frustrating not to mention expensive thing to have your engine's performance limited by the strength of a connecting rod.
2) The rods that Keith has to use are from a relatvely modern car and therefore should be inherently strong and made of good material.
3) Stock rods would live forever in a stock motor that is not capable of reving beyond the limit of the rod
4) Keith is not lightening the rods and is using good practice such as cryo and rem in order to make them live as long as possible.
5) Rods generally don't break on the power stroke because that is when they are in compression and therefore in their strongest configuration, so it is not torque that is breaking them

Therefore, the rods must be breaking because they are being rev'd beyond what they can stand, and that is at only 9.5 to one compression. Aftermarket rods will not only allow the 9.5:1 motor to rev higher, it will allow more things to be done to the motor to allow it to rev even higher or produce more torque and therefore make even more power, since power is direcly related to rpm and torque.

Not saying that Keith and others shouldn't be allowed to make as much power as they want and to rev as high as they want, but we shouldn't think that allowing aftermarket rods won't change the equation some which seems to be what some are saying.

Chris mentions that some modern cars use ultralight rods to increase gas mileage. Ultralight rods could be inherently weak. If that is the case with Keith's Toyota, then maybe there should be a spec line allowance for this engine and not necessarily give an across the board allowance.

 

[JohnMcNaughton]

I have been reading this string as it evolves. My most recent racing was with the RX7 rotary. Didn't have a choice with which rod to use!
No compression, no rods, no torque......

My other 25+ years of racing was with L-16 Datsuns for 4 years. And then evolving to small block Chevy V-8's in excess of 700HP.

A few things I learned:

1) The best stock rods, forged, cast or new age tech, with the best of machine work and Cryo and any other NASA or NASCAR based whiz treatment are still not as strong as Carillo or other name brand rods. Stock rods do not have the durability, even if held to stock or maximum peak RPM. The average RPM's, the sustained RPM's and the total cumulative RPM cycles of a race motor are significantly higher, than the design application of a stock motor driven on the highway. The life cycle of a component is influenced, among other indicators, by the total cycles (RPM total) it has endured. NASCAR, Indy and, other pro teams measure the durability of rotating parts by the cumulative total RPM life of the component. Not just the maximum RPM's sustained in a race, but the total number of engine revoltions sustained during the race. They also consider sustained RPM range, compare Daytona, a range of a few hundred RPM around the entire track, to Bristol, a range of 3,000+ RPM in a single lap.

2) The cost of prepping and machining a block is very expensive. Some of the blocks used in Production racing are getting very rare and are getting more expensive. A single broken rod may also take out a very expensive block, along with possibly the crank, cam, heads and oil pan. Maybe even the water & oil cooling system.

3) Rods do not increase power. They may reduce the power losses because they are lighter, think aluminum drag racing rods. Or, they may increase power losses, because weight and durabilty have a higher priority from the guy buying/building the motor. Lighter parts = rev'$ fa$ter.

4) Rod "length" will move the power band around on the RPM range. Longer rods will generally increase torque, thru longer mechanical leverage. The stock Chevy rod was 5.7". I used as long as 6.125" to increase torque and move the effective range of the power up in the RPM range to take advantage of better heads and intake manifolds.

5) I never broke a Carillo rod. Never had any expensive machine work to do with them. Open the box, clean them off, check the balance and rod clearance, bolt them on. So I never had to worry about the spontaneous loss of a the investment in a very expensive block assembly, Callies crank and roller cam and heads.

6) A set of heavily massaged, properly treated, stock rods usually had broken one of the rods and the block, before 700 race miles. I always replaced the Carillo rods at 3,000 race miles. And I sold the used Carillo's for more than half of my original investment. In the interest of fair and good disclosure practice, I always told the buyer the life history of the part. And they were always ecstatic to have some hi-end parts in their project. Usually a short track car or street hot rod. None of them ever came back to me with a broken or damaged rod. They also make beautiful parts for spare engines, paper weights. Or, add a precision clock in the crank bore and a themometer in the wrist pin bore... Beautiful work of art that can be well sold.

7) The total cost of aftermarket rods is $ignifcantly less when all factors are considered. Higher initial investment, significantly lower operating costs and fewer rebuild$. More time available for racing and working on the suspension. Or waxing the car.

I enjoy building engines, when I am able to schedule them.
And, not when the component schedules the rebuild...

It's not about the power an aftermarket rod yields. It is all about the simple reliability. Or, is that what the LP engines are supposed to do??? So many choices!

I hate creating confusion