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Engine Question

19USMC69

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Does anyone have a “cut-a-way” pic of a cup engine? I’m interested in push rod length. I’m told they are relatively short. If so, I’d like to see how it’s done.
 

aunty dive

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Camshaft location ... higher in the block in all 3 manufacturer’s Cup engines. By design.

Shorter pushrods reduced the extreme valve train angles that were causing component / engine failures in the older engines.
 

Formerjackman

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The R07 pushrods may well be shorter than the SB2, but I doubt they are substantially shorter. Yes, the camshaft is further up in the block, but the R07 cylinder heads are also rather tall. Since NASCAR instituted the gear rules, valve train issues have mostly become a moot point anyway, and it's not like the SB2s were regularly spitting out pushrods, even when RPM were inching towards the 10,000 mark.
 

aunty dive

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^ This is why we can’t have nice things.

“The R07's camshaft is located higher in the block than the camshaft in the SB2. The raised cam operates pushrods that are correspondingly shorter and stiffer, thereby improving valvetrain dynamics at high rpm.”

From Lew’s link.

The current engines are coming up on 12 or 13 years old. A lot of things have changed since the design briefs were written, including gear rules and computer controlled rev limiters among others.
 

Formerjackman

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Yes, they are shorter, but not by a lot. The comments make it seem like they are only half the length of an SB2. Also, part of the reason they are stiffer is because they are a larger diameter than the SB2 permitted.
 

OldTimer

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Yes, they are shorter, but not by a lot. The comments make it seem like they are only half the length of an SB2. Also, part of the reason they are stiffer is because they are a larger diameter than the SB2 permitted.
Believe .375 comes to mind...someone told me that they are the same length as the old Ford 289.
 

Formerjackman

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Hey, a question was asked, and I tried to answer it as absolutely accurately as I could. If I had asked the question, I would want as much. I spent 45 freakin minutes last night trying to find the actual dimensions, and never did find the answer, but I have spent CONSIDERABLE time examining display models and actual cutaways of the R07, so I am fairly familiar with most of the parts.
 

aunty dive

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Hey, a question was asked, and I tried to answer it as absolutely accurately as I could. If I had asked the question, I would want as much. I spent 45 freakin minutes last night trying to find the actual dimensions, and never did find the answer, but I have spent CONSIDERABLE time examining display models and actual cutaways of the R07, so I am fairly familiar with most of the parts.
You made no attempt to answer the question.

You’re so familiar with RO7 architecture that you’re willing to dispute the veracity of the statements made by people who designed and built the thing.

FYI, a standard SB2 pushrod is 7.800” long. The new ones are far more than 0.375“ shorter.

While you’re looking maybe you’ll find out that the CGI blocks for the RO7 are cast in Brazil.
 

KTMLew01

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You made no attempt to answer the question.

You’re so familiar with RO7 architecture that you’re willing to dispute the veracity of the statements made by people who designed and built the thing.

FYI, a standard SB2 pushrod is 7.800” long. The new ones are far more than 0.375“ shorter.

While you’re looking maybe you’ll find out that the CGI blocks for the RO7 are cast in Brazil.
I did what I could with calling Hendrick Moterspertz.
 

OldTimer

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You made no attempt to answer the question.

You’re so familiar with RO7 architecture that you’re willing to dispute the veracity of the statements made by people who designed and built the thing.

FYI, a standard SB2 pushrod is 7.800” long. The new ones are far more than 0.375“ shorter.

While you’re looking maybe you’ll find out that the CGI blocks for the RO7 are cast in Brazil.
The raised camshaft still cannot be more than 6.150" above the center line of the crankshaft, how much shorter than the nominal average (there are many variations of possible push rod lengths depending on lobe, rocker ratio, and rocker design) 7.8" long in the SB2. But...the height of the camshaft in the block between the two is not that much.
 

KTMLew01

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The raised camshaft still cannot be more than 6.150" above the center line of the crankshaft, how much shorter than the nominal average (there are many variations of possible push rod lengths depending on lobe, rocker ratio, and rocker design) 7.8" long in the SB2. But...the height of the camshaft in the block between the two is not that much.
Plus the heads are so tall on the intake side the pushrods can't be too much shorter. But they have gone to canted valves so who knows. Maybe I'll call Rick and ask. Worked for him briefly in 1996/97.
 

Formerjackman

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You made no attempt to answer the question.

You’re so familiar with RO7 architecture that you’re willing to dispute the veracity of the statements made by people who designed and built the thing.

FYI, a standard SB2 pushrod is 7.800” long. The new ones are far more than 0.375“ shorter.

While you’re looking maybe you’ll find out that the CGI blocks for the RO7 are cast in Brazil.
I NEVER disputed that they were shorter. What I said is that they are not a LOT shorter. I never mentioned the .375" number, I don't know how that got into the conversation. The original poster offered up the phrase "relatively short" My response was TRYING to make the point that I would NOT characterize them that way at all. To me, "relatively short" would imply something five inches or less.

Why are you obsessed with where the blocks are cast? Is that supposed to be important for some reason? To my memory, and at least partially confirmed by the photos I have taken, I don't believe the country of origin is marked anywhere on the parts themselves. At least SOME of Hendrick's connecting rods are made by Pankl in Germany. Is THAT important?
 

OldTimer

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I never mentioned the .375" number,
I did...because that is nominal difference between the pushrod when comparing apple to apple of the SB2 and R07 and the utilizing the same rocker ration. 3/8" is the nominal difference. But using a different rocker ratio, and lobe height...it is possible to make as much as a 1/2" difference.....which is huge. In generalization, the R07 has what I describe as 289 push rods (much larger diameter though) compared to the SB2 having the equivalent of 351W push rods.

Keep in mind that the deck height of the R07 is much lower than the SB2, so there might be some optical illusion going on there. The R07 makes up for much of the difference in the head height.
 

Formerjackman

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Ok, if we are to accept the numbers put out here, and I have no reason not to at this point, then the R07 pushrod is roughly 15% shorter than the SB2 pushrod. I'll ask the question again. Is 15% shorter what the original poster had in mind when he wrote "relatively short"? I didn't take it that way. If I'm wrong, excuse the hell out of me for living.
 

OldTimer

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Ok, if we are to accept the numbers put out here, and I have no reason not to at this point, then the R07 pushrod is roughly 15% shorter than the SB2 pushrod. I'll ask the question again. Is 15% shorter what the original poster had in mind when he wrote "relatively short"? I didn't take it that way. If I'm wrong, excuse the hell out of me for living.
It is a combination of things. But "relatively shorter" can be used as one part of a sequence of the whole. Raising the height of the camshaft relative to the centerline of the crankshaft also changes the angle of the pushrod. The theory is that when the valve is fully open and most susceptible to valve fibrillation, the angle on the R07 helps to that from happening.
 

Formerjackman

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That's all perfectly fine, but the OP specifically asked if the pushrods were short. It is my point of view that while they may be shorter than their predecessor, they are not short. If you are 6' 4" and I am 5' 11", I am shorter than you are , but I am not short. If anybody here wants to make the case that the R07 pushrod is short, that's fine. You are entitled to your opinion, as am I. I'm done with it.
 

aunty dive

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Keep in mind that the deck height of the R07 is much lower than the SB2, so there might be some optical illusion going on there. The R07 makes up for much of the difference in the head height.
The deck height of an RO7 block is 9.0"

The deck height of an SB2 block is 9.025" ... how much is much?
Ok, if we are to accept the numbers put out here, and I have no reason not to at this point, then the R07 pushrod is roughly 15% shorter than the SB2 pushrod. I'll ask the question again. Is 15% shorter what the original poster had in mind when he wrote "relatively short"? I didn't take it that way. If I'm wrong, excuse the hell out of me for living.
That's all perfectly fine, but the OP specifically asked if the pushrods were short. It is my point of view that while they may be shorter than their predecessor, they are not short. If you are 6' 4" and I am 5' 11", I am shorter than you are , but I am not short. If anybody here wants to make the case that the R07 pushrod is short, that's fine. You are entitled to your opinion, as am I. I'm done with it.
You've split more hairs here than you did in the Days of Thunder thread.
 

Churchkey

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The RO7 camshaft is raised because it is separated from the crankcase, pushrod length is not a factor.
 

aunty dive

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The raised camshaft still cannot be more than 6.150" above the center line of the crankshaft, how much shorter than the nominal average (there are many variations of possible push rod lengths depending on lobe, rocker ratio, and rocker design) 7.8" long in the SB2. But...the height of the camshaft in the block between the two is not that much.
6.150" vs 4.521" for the SB2

I'm done now.

The RO7 camshaft is raised because it is separated from the crankcase, pushrod length is not a factor.
I'm done now.
 

KTMLew01

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That's all perfectly fine, but the OP specifically asked if the pushrods were short. It is my point of view that while they may be shorter than their predecessor, they are not short. If you are 6' 4" and I am 5' 11", I am shorter than you are , but I am not short. If anybody here wants to make the case that the R07 pushrod is short, that's fine. You are entitled to your opinion, as am I. I'm done with it.
Somehow I doubt it.


I-dont-believe-you.gif
 

OldTimer

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he deck height of an RO7 block is 9.0"

The deck height of an SB2 block is 9.025" ... how much is much?
Add that 25 thou to the higher cam placement in the block....and guess what you get.

But the nominal difference between the 6.150" of the R07 is offset by the height of the R07 heads....and the valve canting.
 

KTMLew01

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Add that 25 thou to the higher cam placement in the block....and guess what you get.

But the nominal difference between the 6.150" of the R07 is offset by the height of the R07 heads....and the valve canting.
As I suggested. And 90% of what i know about the SB2 & RO7 I learned in this thread. But all you have to do to see the difference between the two is look at the intake manifold. That sucker is TALL! Almost straight shot into valve bowl area due to the intake port being raised. I used to love the articles on engine development. Remember the one about Ernie Elliott's Australian Cleveland blocked motors back in the 80's? Now it's all secret. Everything is secret. They keep dumbing it all down. Great thing about NHRA. They at least attempt to explain the technical aspects. I've loved this thread.
 

aunty dive

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Add that 25 thou to the higher cam placement in the block....and guess what you get.

But the nominal difference between the 6.150" of the R07 is offset by the height of the R07 heads....and the valve canting.
I'll guess shorter pushrods.

If I didn't know better, I'd think you ladies were arguing to the contrary. The head issue is a valid point ... give me the measurement from the centerline of the rocker arm shaft(s) to the deck surface in each case and we'll talk.
 

KTMLew01

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I'll guess shorter pushrods.

If I didn't know better, I'd think you ladies were arguing to the contrary. The head issue is a valid point ... give me the measurement from the centerline of the rocker arm shaft(s) to the deck surface in each case and we'll talk.
I took the original poster as thinking the pushrods were what I would consider short which would be @ or under 5". Now i just pulled that number out of my rectal cavity butt it's based on every automotive engine i've ever seen. The 60* GM engines are even longer than that. They are the shortest I can think of. Aagin, what IS is?
 

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OldTimer

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I'll guess shorter pushrods.

If I didn't know better, I'd think you ladies were arguing to the contrary. The head issue is a valid point ... give me the measurement from the centerline of the rocker arm shaft(s) to the deck surface in each case and we'll talk.
Just FYI...Ford 289 pushrods are nominally 6.8" long... an inch shorter than the SB2....my original assumption was that the R07 has similar length pushrods as the 289 Ford (+/- a few thou).
 

Greg

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All this math stuff is makin my head hurt
I dont know why everybody is so worked up with the lengths and measurements.

If I was building engines for midget race cars I could see getting worked up about the length of the pushrods. I would probably want shaved the heads for an extremely tight too. I even heard some talk about Brazilian engine blocks for those wanting more than a shave.
All the midget engine technology stuff.
 

Spotter22

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I dont know why everybody is so worked up with the lengths and measurements.

If I was building engines for midget race cars I could see getting worked up about the length of the pushrods. I would probably want shaved the heads for an extremely tight too. I even heard some talk about Brazilian engine blocks for those wanting more than a shave.
All the midget engine technology stuff.
knife edge crank ;)
 
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