As I recall the 320 gear rule was an attempt to slow the cars down at the time.When the big dogs were running 2:90 gears and lunching rear ends on the starting line. NHRA stepped in and helped the racers help themselves by requiring 3:20. End of problem.
Some thoughts on the reasons for existing NHRA rules... (1 Viewer)
- Thread starter Bill
- Start date
Treeshaker
Nitro Member
Turbos are working today with EFI injection and controlled wastegates. I don't think there is an EFI system available today that will handle 120 gallons per minute of nitro. Exhaust pressures and heat would kill the turbo. One of those come apart and it would cause a lot of damage. Back in the day that you keep referring to, clutch management wasn't around and the turbo car had unpredictable horsepower. Smoking the tires is usually caused by the clutch catching up to the motor and locking up causing too much wheel speed, thus spinning/smoking. Add controlled horsepower earlier and the motor will stay ahead of the clutch causing clutch slippage and no tire smoke. Same with wheel stands, not enough power to drive through the clutch for slippage, and if there isn't enough wheel speed generated, the car will do a wheel stand.
The hot set up when I started racing a fuel funny car was a 3.70 gear and clutch management was just beginning. I found, as did others that going to a 3.50, then 3.30, then 3.20 and then 2.90 gear was viable with the clutch management systems, and we increased speeds along with lower ET's. Gear manufacturers got tired of making runs of the latest gear ratio and not selling the whole run before racers changed ratios. When it got to the 3.20 and 2.90, the manufacturers started making the racers buy a whole run of the gears and it was getting expensive. So it was decided to stop at the 3.20 ratio, thus the ratio rule. All of these ratios were for the 9" Ford Pro gear that had the bigger diameter pinions. As these started breaking with the extra strain on them at lock up they were upgraded to the 9.5" ring gear. As these started breaking, some teams changed them every run, we would get 2 -3 at the most, the 10.5" rear came out but was quickly replaced with the 12" ring gear using the tooling from a Chevy truck rear. At that time we were paying $1,700.00 to $2,000.00 for a single ring and pinion but you could run all year on one set where before we were buying the 9.5" thirty at a time.
Once the rear end ratio was settled, ET's were lowered with the clutches and mph was dictated by blower design. And once the blowers got close to optimum, head design took a huge leap. Changing from an AJPE stage 6 to a stage 7 will make your engine rpm 300 - 400 rpm more at the hit. And now you are seeing the results of just changing the angle of the exhaust pipes have had on the funny cars, along with the expense of the experimenting. Along the way was a lot of injector shape experimenting (on the inside where fans can't see it), chassis design (again under the bodies where fans don't notice), camshaft work to go along with the blower, clutch, head, injector development,
I was in the top end stands at Dallas when Ray Higley lost his exhaust just past half track and actually flew from there and landed in the shut down area hitting John Force.
The hot set up when I started racing a fuel funny car was a 3.70 gear and clutch management was just beginning. I found, as did others that going to a 3.50, then 3.30, then 3.20 and then 2.90 gear was viable with the clutch management systems, and we increased speeds along with lower ET's. Gear manufacturers got tired of making runs of the latest gear ratio and not selling the whole run before racers changed ratios. When it got to the 3.20 and 2.90, the manufacturers started making the racers buy a whole run of the gears and it was getting expensive. So it was decided to stop at the 3.20 ratio, thus the ratio rule. All of these ratios were for the 9" Ford Pro gear that had the bigger diameter pinions. As these started breaking with the extra strain on them at lock up they were upgraded to the 9.5" ring gear. As these started breaking, some teams changed them every run, we would get 2 -3 at the most, the 10.5" rear came out but was quickly replaced with the 12" ring gear using the tooling from a Chevy truck rear. At that time we were paying $1,700.00 to $2,000.00 for a single ring and pinion but you could run all year on one set where before we were buying the 9.5" thirty at a time.
Once the rear end ratio was settled, ET's were lowered with the clutches and mph was dictated by blower design. And once the blowers got close to optimum, head design took a huge leap. Changing from an AJPE stage 6 to a stage 7 will make your engine rpm 300 - 400 rpm more at the hit. And now you are seeing the results of just changing the angle of the exhaust pipes have had on the funny cars, along with the expense of the experimenting. Along the way was a lot of injector shape experimenting (on the inside where fans can't see it), chassis design (again under the bodies where fans don't notice), camshaft work to go along with the blower, clutch, head, injector development,
I was in the top end stands at Dallas when Ray Higley lost his exhaust just past half track and actually flew from there and landed in the shut down area hitting John Force.
Treeshaker
Nitro Member
I was at MIR tuning my son Richard's NFC this past weekend. We get to take it out about 4 times a year and have ran as quick as 5.60 @ 259.82 at Martin Michigan late last year. This past weekend our best was a 5.74 @ 257. I also do some telephone consulting periodically.
DrRocket
Nitro Member
Good stuff Virgil.
As Virgil's post shows, there's almost always a background story behind the rules, most of which, by their nature, are "reactive" rule changes. Sort of like NASCAR's fabled "Smokey Yunick" rules, rules passed on Monday morning to ban what he'd gotten away with the prior Sunday.
As Virgil's post shows, there's almost always a background story behind the rules, most of which, by their nature, are "reactive" rule changes. Sort of like NASCAR's fabled "Smokey Yunick" rules, rules passed on Monday morning to ban what he'd gotten away with the prior Sunday.
Bill
Nitro Member
Virgil. I really appreciate your input on this stuff that fans (like ME) could not possibly know about as you do, because you were THERE... it's fascinating to hear the "back-story" on things like, where the gear-ratio rule came from, for example.
Do you have any information as to why NHRA would ban pneumatic valve springs? It seems like compressed-air springs could save the alcohol racers a lot of money....
Thanks for your great replies!!!
Bill
Treeshaker
Nitro Member
I do not know anything about pneumatic valve springs. I do know that seat pressures on fuel motors have went from 150 lbs when I started to 650 lbs for some of todays teams. A current team installs new springs at 575 lbs on the intakes, they settle to 550 lbs and they last for about 20 - 25 runs before losing pressure. Then they put them on the exhaust at 475 lbs and run them another 20 - 25 runs. I know of another team that buys used springs really cheap and sets theirs at about 425 lbs and again run them for about 20 runs. So it just doesn't seam to be a really big expense for these teams, at least not big enough to seek an alternative method.
You should remember that today's intake valves are 2.470" diameter with a lot of pressure in the manifold behind the valve, and with the radical high lift cams it takes a lot to keep the valve on the seat for a good seal and to keep the lifter on the cam without bouncing. Teams shoot for 8400 - 8700 rpm at the hit with initial blower boost in the 48 to 52 PSI range. Exhaust valves are much smaller and do not have the blower pressure pushing on their back side. F1 valves are miniature pieces in comparison.
You should remember that today's intake valves are 2.470" diameter with a lot of pressure in the manifold behind the valve, and with the radical high lift cams it takes a lot to keep the valve on the seat for a good seal and to keep the lifter on the cam without bouncing. Teams shoot for 8400 - 8700 rpm at the hit with initial blower boost in the 48 to 52 PSI range. Exhaust valves are much smaller and do not have the blower pressure pushing on their back side. F1 valves are miniature pieces in comparison.
If I recall correctly, the reason for pneumatic valve train is eliminate valve float at high RPMs. Not sure of the valve pressure in an F1 engine and if they could make a pneumatic system for the valve pressure in an alcohol or fuel engine. I think one of the concerns would be the material used for the casing. If can see if that goes, more dropped intake valves meaning more kabooms.
Bill
Nitro Member
Virgil.
All good information; thanks for that.
Speaking from ignorance here, I was not aware that the Fuel motors turned that many rpm. I had heard that the alcohol motors turned a lot faster and that their valve springs lasted a lot less, on the order of three or four runs. That is why I thought a pneumatic system would pay off for them. Those alcohol motors in the dragsters at the hit, SOUND like they are turning way up there... are they not?
Again, thanks for any information.
Bill
Bill
Nitro Member
Tom,
I m sure what you say is correct... those issues are critical at the elevated rpm's these engines turn. I also think that the fact that they are asked to "go the distance," sometimes hours at a time at 20,000 rpm, plays into the rationale. That would be askingg a lot, of steel valve springs, to survive that extended torture.
I don't KNOW that; it just seems logical to me...
Thanks for your comments!
Bill
Sean D, shondoo
Nitro Member
For what's it's worth, when we began our foray into competition level valve springs, all the blown alcohol guys were killing the springs, while Reichert said he hardly had any valve spring problems. And it seems to me I remember him saying he was in basically the same RPM range that Virgil spoke of.
Sean D
Sean D, shondoo
Nitro Member
Exactly. I also seem to remember him saying the cam profiles weren't as aggressive in the A-fuel combination either, which if true would make a major difference in spring life as well.
Sean D
none
Nitro Member
Hey Bill,
Here's a blast from the past that I think you might find interesting, it's the classic "Spring Story" from when I was working in the Pro Stock world on a professional level. You can't buy the education that I got there at any price and it's the reason that I'm not allowed in most Pro Stock shops to this day. As Greg Anderson said to me earlier this year when I asked if I might stop by, "No way! You know too much!"
This was around 2000-2001 so the RPM was lower then, but the story relates to this day. The springs have gotten better, so the RPM is higher, but you always want more. It's the reason that NHRA finally said "Enough is enough" and instituted the 10,500 RPM limit.
Enjoy.......
When I was working with Nickens Brothers one of the biggest issues was valve springs (it still is). The life expectancy of an intake spring was maybe three runs if all went well and the driver didn’t over-rev the thing. Exhaust was a little more forgiving, but not much. At the time we were trying to shift at 9500. The HEMI ran more RPM then the wedge stuff at that time. If the driver ran it to 9600 in any gear the eight intake springs would be junk. At 9750, just get out a box, because you didn’t even need to check them, all 16 were going in the trash and you would be beating the retainers loose. Anybody who has ever been around high RPM engines knows exactly what I mean by that.
Even when the car ran well and the driver hit all the shifts on time we would come back and find two or three springs that needed to be changed. Now assuming that they didn’t wear out while the car was being towed back from the far end, when did the springs give up? Third gear? Or fourth? Or as the car crossed the stripe? If you can figure that out, you are smarter than I am. It seemed pretty obvious that if we could keep the springs up to pressure that the valves would stay under control and there had to be some performance that was there for the taking if only we had better springs.
One advantage that we had was that we were the factory MOPAR team and Chrysler was one of the principles in Ilmor. If you haven’t heard of Ilmor they are an engineering firm in England they are involved with Formula 1 and with Penske on his Cup stuff. Racing is their whole world and we’re talking about some really smart guys. Initially we sent them all of the valvetrain components that we were running at the time and explained that we couldn’t keep springs on the thing. The answer that they came up with was that no one in their right mind would use these parts in any engine much less trying to race this stuff. Keep in mind that an F-1 engineer has probably never seen a push rod! So, they sent a couple of guys to Houston to check out firsthand what we were doing and try to find a better way. One of the guys had a PHD in mechanical engineering and the other was right there with him in the brains department. They had spent some time working on Cup stuff for Penske so they had a little understanding of the type of engine we were running but when they saw the first Pro Stock HEMI they were blown away. We explained to them that a new spring would lose 40 lbs or so on the first run. They told us that if a Cup spring lost 8 lbs after 500 miles they would be fired. We had the right guys work on this now.
Step one was on the Spintron. I was the Spintron operator, if you’re not familiar with that machine is has a 75 HP electric motor and it will spin the valvetrain components without worrying about blowing up an engine. So you can check stability, valve float and bounce and any number of things. If you drop a valve on the Spintron you will be down about ten minutes. So it is the perfect tool to find the limits of stuff. The valve movement is tracked in real time by a laser in the cylinder. Just Google them if you want more info. One of the toys they brought from Ilmor was a load cell that goes under the spring (we machined a deeper pocket to accept it) and would tell us spring seat pressure IN REAL TIME with the valvetrain spinning at 9500 RPM. It was cool! And really enlightening. What we learned was that the spring was so out of control above about 7200 you couldn’t tell what was going on. There was a lot of room for improvement and they believed that they could help us. I jokingly told them that all we wanted was a spring that would run to 10,000 RPM and last for a season. His response was “Why would you change them after only one season?” We were on the same page. Two and a half days of trying to wear out the Spintron and Dyno and they had the information that was needed to go build us springzilla. They contacted us a couple of weeks later and said that after analyzing the data from the tests the main problem was that the camshaft was so aggressive that when the engine was running at high RPM the valve was being pushed open so fast, the first coil of the spring would smash into the second coil before it could move out of the way. The second coil would then be sent flying into the third coil and so on. Now just for kicks, get yourself a valve spring and try to get the first coil to touch the second one without the second one moving. They had an answer, they could build us a new spring that would stand up to what we were trying to do with it. We couldn’t wait.
They came back to the states a few weeks later with the new spring. It didn’t look much different but they assured us they would cure all of our valvetrain issues. It was time to fire up the Spintron. With the old springs if I took it to 9800 RPM the spring would break almost immediately and I do mean in seconds, before you could even get a reading. I put one of the new springs on and ask where do you want to start (8000 was the usual point). He said it didn’t matter I couldn’t break it. I love a challenge so I set the machine for 10,000 and ask again, he ask what I was waiting for so I hit start! At ten grand the valve was as happily under control at it used to be at 8000. I couldn’t believe what I was watching. After about thirty seconds at 10,000 he told me I could probably take my hand off the emergency stop button, because his spring wasn’t going to break. We spent most of that afternoon doing more testing on the Spintron and this spring was magic. It controlled the valves as good as the old springs at lower RPM and didn’t wear out. The first spring lost 10 lbs of seat pressure after ripping on it all afternoon. It was now Dyno Time.
The next morning we put one of the race engines on the pump, warmed it up and made a baseline hit. Then we changed the springs. We made four or five pulls and it was within a half a horsepower. Changed springs back and it repeated perfectly. The next race was Reading and we couldn’t wait. Those guys won’t know what hit them. We had the magic springs. We had found the cure for the biggest problem we had and couldn’t wait to unleash it on them.
Reading didn’t go quite like we had planned, both cars qualified bottom half and lost first round. We just never got a handle on it. We also made ten runs (five with each car) and never had to change a spring. Back at the shop the engines went back on the pump and were fine, right where they should be. We checked the cars, and couldn’t find any problems. It was just a bad weekend. Off to the next race, the cars were still slow. No reason, nothing we could find wrong, just slow. We went testing when we got back and couldn’t get the cars to run, finally after exhausting everything we could think of David ask what’s different? We had changed ignition boxes, batteries, carbs. You name it we changed it. The only thing left was the springs, but we knew they were good, we could check them and they were fine.
The next day at the track testing we opened up with a 6.86 199 not very good. Second run 6.87 199. David ask if we had any of the old springs? Yeah, there were still some in the trailer. Let’s change them. O.K. you’re the boss, but the springs aren’t the problem, they are fine.
New (old) springs, back to the line 6.80 202! That’s more like it. Back at the trailer two springs down 100+ lbs and one with a broken inner. Replace three springs, back to the line 6.79 202 but it still can’t be the springs, can it? We put the magic springs back on and ran 6.86 198, change to the old springs and made one last hit for the day. 6.79 203 and wiped out four springs.
When we called the Ilmor guys and explained it to them, they decided that you just can’t help some people. I have still never found anyone that can explain it to me and if I hadn’t been there and lived it I’m not sure I would believe it either, but they springs wouldn’t go down the track. We started changing 3 or 4 springs every run and being fast again.
Here's a blast from the past that I think you might find interesting, it's the classic "Spring Story" from when I was working in the Pro Stock world on a professional level. You can't buy the education that I got there at any price and it's the reason that I'm not allowed in most Pro Stock shops to this day. As Greg Anderson said to me earlier this year when I asked if I might stop by, "No way! You know too much!"
This was around 2000-2001 so the RPM was lower then, but the story relates to this day. The springs have gotten better, so the RPM is higher, but you always want more. It's the reason that NHRA finally said "Enough is enough" and instituted the 10,500 RPM limit.
Enjoy.......
When I was working with Nickens Brothers one of the biggest issues was valve springs (it still is). The life expectancy of an intake spring was maybe three runs if all went well and the driver didn’t over-rev the thing. Exhaust was a little more forgiving, but not much. At the time we were trying to shift at 9500. The HEMI ran more RPM then the wedge stuff at that time. If the driver ran it to 9600 in any gear the eight intake springs would be junk. At 9750, just get out a box, because you didn’t even need to check them, all 16 were going in the trash and you would be beating the retainers loose. Anybody who has ever been around high RPM engines knows exactly what I mean by that.
Even when the car ran well and the driver hit all the shifts on time we would come back and find two or three springs that needed to be changed. Now assuming that they didn’t wear out while the car was being towed back from the far end, when did the springs give up? Third gear? Or fourth? Or as the car crossed the stripe? If you can figure that out, you are smarter than I am. It seemed pretty obvious that if we could keep the springs up to pressure that the valves would stay under control and there had to be some performance that was there for the taking if only we had better springs.
One advantage that we had was that we were the factory MOPAR team and Chrysler was one of the principles in Ilmor. If you haven’t heard of Ilmor they are an engineering firm in England they are involved with Formula 1 and with Penske on his Cup stuff. Racing is their whole world and we’re talking about some really smart guys. Initially we sent them all of the valvetrain components that we were running at the time and explained that we couldn’t keep springs on the thing. The answer that they came up with was that no one in their right mind would use these parts in any engine much less trying to race this stuff. Keep in mind that an F-1 engineer has probably never seen a push rod! So, they sent a couple of guys to Houston to check out firsthand what we were doing and try to find a better way. One of the guys had a PHD in mechanical engineering and the other was right there with him in the brains department. They had spent some time working on Cup stuff for Penske so they had a little understanding of the type of engine we were running but when they saw the first Pro Stock HEMI they were blown away. We explained to them that a new spring would lose 40 lbs or so on the first run. They told us that if a Cup spring lost 8 lbs after 500 miles they would be fired. We had the right guys work on this now.
Step one was on the Spintron. I was the Spintron operator, if you’re not familiar with that machine is has a 75 HP electric motor and it will spin the valvetrain components without worrying about blowing up an engine. So you can check stability, valve float and bounce and any number of things. If you drop a valve on the Spintron you will be down about ten minutes. So it is the perfect tool to find the limits of stuff. The valve movement is tracked in real time by a laser in the cylinder. Just Google them if you want more info. One of the toys they brought from Ilmor was a load cell that goes under the spring (we machined a deeper pocket to accept it) and would tell us spring seat pressure IN REAL TIME with the valvetrain spinning at 9500 RPM. It was cool! And really enlightening. What we learned was that the spring was so out of control above about 7200 you couldn’t tell what was going on. There was a lot of room for improvement and they believed that they could help us. I jokingly told them that all we wanted was a spring that would run to 10,000 RPM and last for a season. His response was “Why would you change them after only one season?” We were on the same page. Two and a half days of trying to wear out the Spintron and Dyno and they had the information that was needed to go build us springzilla. They contacted us a couple of weeks later and said that after analyzing the data from the tests the main problem was that the camshaft was so aggressive that when the engine was running at high RPM the valve was being pushed open so fast, the first coil of the spring would smash into the second coil before it could move out of the way. The second coil would then be sent flying into the third coil and so on. Now just for kicks, get yourself a valve spring and try to get the first coil to touch the second one without the second one moving. They had an answer, they could build us a new spring that would stand up to what we were trying to do with it. We couldn’t wait.
They came back to the states a few weeks later with the new spring. It didn’t look much different but they assured us they would cure all of our valvetrain issues. It was time to fire up the Spintron. With the old springs if I took it to 9800 RPM the spring would break almost immediately and I do mean in seconds, before you could even get a reading. I put one of the new springs on and ask where do you want to start (8000 was the usual point). He said it didn’t matter I couldn’t break it. I love a challenge so I set the machine for 10,000 and ask again, he ask what I was waiting for so I hit start! At ten grand the valve was as happily under control at it used to be at 8000. I couldn’t believe what I was watching. After about thirty seconds at 10,000 he told me I could probably take my hand off the emergency stop button, because his spring wasn’t going to break. We spent most of that afternoon doing more testing on the Spintron and this spring was magic. It controlled the valves as good as the old springs at lower RPM and didn’t wear out. The first spring lost 10 lbs of seat pressure after ripping on it all afternoon. It was now Dyno Time.
The next morning we put one of the race engines on the pump, warmed it up and made a baseline hit. Then we changed the springs. We made four or five pulls and it was within a half a horsepower. Changed springs back and it repeated perfectly. The next race was Reading and we couldn’t wait. Those guys won’t know what hit them. We had the magic springs. We had found the cure for the biggest problem we had and couldn’t wait to unleash it on them.
Reading didn’t go quite like we had planned, both cars qualified bottom half and lost first round. We just never got a handle on it. We also made ten runs (five with each car) and never had to change a spring. Back at the shop the engines went back on the pump and were fine, right where they should be. We checked the cars, and couldn’t find any problems. It was just a bad weekend. Off to the next race, the cars were still slow. No reason, nothing we could find wrong, just slow. We went testing when we got back and couldn’t get the cars to run, finally after exhausting everything we could think of David ask what’s different? We had changed ignition boxes, batteries, carbs. You name it we changed it. The only thing left was the springs, but we knew they were good, we could check them and they were fine.
The next day at the track testing we opened up with a 6.86 199 not very good. Second run 6.87 199. David ask if we had any of the old springs? Yeah, there were still some in the trailer. Let’s change them. O.K. you’re the boss, but the springs aren’t the problem, they are fine.
New (old) springs, back to the line 6.80 202! That’s more like it. Back at the trailer two springs down 100+ lbs and one with a broken inner. Replace three springs, back to the line 6.79 202 but it still can’t be the springs, can it? We put the magic springs back on and ran 6.86 198, change to the old springs and made one last hit for the day. 6.79 203 and wiped out four springs.
When we called the Ilmor guys and explained it to them, they decided that you just can’t help some people. I have still never found anyone that can explain it to me and if I hadn’t been there and lived it I’m not sure I would believe it either, but they springs wouldn’t go down the track. We started changing 3 or 4 springs every run and being fast again.
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Sean D, shondoo
Nitro Member
I've read your account of that story before, Alan. As a springmaker, I would almost have given my left arm to have gotten my hands on one of those springs...... Lol
Sean D
Sean D
none
Nitro Member
The best part was that everything being done at Illmor was pretty much a Top Secret Project and as such every project had a code name. Our spring was known as the "FEM Valve Spring project" The engineers told us that E stood for Expensive and M for Material, can you guess what F was? LoL True story.
I'm not sure if they still have any or not, at one point I used a set on a Top Dragster engine, because it wouldn't really matter if it was a couple hundredths slow, and the car went 3 seasons without ever changing a spring.
Alan
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Bill
Nitro Member
Alan, I appreciate the time you took to post that, It is difficult to understand how a valve spring that apparently does eveything "right" can have such a negative effect on an engine's performance. All those springs can do (if they perform flawlessly,) is to keep the lifters in constant contact with the cam lobes... as far as I know, there isn't anything else... is there (parts-breakage, aside...)? Well, there is additional parasitic drag, but that doesn't seem to have been a factor, and harmonics, but the Spintron should have identified that, IF ithey were creating problems.
I dunno, but as interesting as it is (and, it IS interesting,) it doesn't shed any light on the reason(s) NHRA would see fit to ban pneumatic valve springs across the board, in all compeittion.
And, they have...
Bill
I dunno, but as interesting as it is (and, it IS interesting,) it doesn't shed any light on the reason(s) NHRA would see fit to ban pneumatic valve springs across the board, in all compeittion.
And, they have...
Bill
none
Nitro Member
Bill,
I wasn't addressing the pneumatic valve spring ban, I was simply posting what I think is an interesting story about valve-train issues. There is a lot that goes on in a race engine that defies logical explanation, but it still happens.
And I don't have any idea what the initial cost would be, but you would certainly need more than one set. To think otherwise is quite naive. For a team like Elite Motorsports (Just picking a name out of the sky) they would have to buy at least 20 complete units. You don't have time in between rounds to change pneumatics any more than valve springs if you have to swap engines between rounds. Even in the Dyno room, you would need many sets. I would imagine that if the Pro Stock teams or the Alcohol teams believed that there was a significant cost savings to be had and asked NHRA for acceptance that acceptance would be granted. I can't see why it wouldn't, and I don't know of anyone who has petitioned for it.
Again, this is strictly my opinion.
Why has NASCAR banned roller cams? Sometimes there is a reason for a rule that makes sense on a level that I'm not aware of.
Alan
I wasn't addressing the pneumatic valve spring ban, I was simply posting what I think is an interesting story about valve-train issues. There is a lot that goes on in a race engine that defies logical explanation, but it still happens.
And I don't have any idea what the initial cost would be, but you would certainly need more than one set. To think otherwise is quite naive. For a team like Elite Motorsports (Just picking a name out of the sky) they would have to buy at least 20 complete units. You don't have time in between rounds to change pneumatics any more than valve springs if you have to swap engines between rounds. Even in the Dyno room, you would need many sets. I would imagine that if the Pro Stock teams or the Alcohol teams believed that there was a significant cost savings to be had and asked NHRA for acceptance that acceptance would be granted. I can't see why it wouldn't, and I don't know of anyone who has petitioned for it.
Again, this is strictly my opinion.
Why has NASCAR banned roller cams? Sometimes there is a reason for a rule that makes sense on a level that I'm not aware of.
Alan
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