How high are PS engines winding now?

[sdwarf36]

Re: How high are PS engines winging now?

John;

A lot of the engines that I have worked with, like to be shifted around 10300 and go thru the traps at about 10400. I would speculate that the fast cars are about 10500 on the shifts and 10550 at the stripe.

Jim

I dunno-- a newbie with only 16 posts--not sure that's enough 'mater-cred....

J/K-thanks for posting Jim!

 

[Nick Name]

Re: How high are PS engines winging now?

The rotating assemblies can take a lot of RPM, it's the valvetrain that's the weak spot. That's why F1 went to pneumatic valves. Pneumatic valve springs - Wikipedia, the free encyclopedia

And the story you're thinking of was posted right here on Nitromater by none other than Alan Reinhart. I believe he was working with Nickens at the time.

Then there is piston speed. F1 engines probably have less than half the stroke a 500 ci PS motor has so it can turn twice the RPM with the same piston speed.

 

[Paul]

Re: How high are PS engines winging now?

I believe it was Reinhart that told us the story. If I remember correctly, it was something to do with a Spinatron (sp?) and they were testing it at Nickens shop. Had something to do with somebody that could build a better valve spring. Alan refresh my memory here.

Valve springs are definitely a critical component in 10,000+ RPM push rod engines. My company, Power Technology ( Power Technology ), builds the valve spring testers used by most of the top Pro Stock engine builders (WJ, Cagnazzi, Jenkins, Maskin, Schmidt) and its been pretty interesting to watch the development of the valve springs used by these engine builders.

When we first introduced the tester back in '93, our 1000 lb max test pressure was fine for the springs in use at that time. But as the engine RPM's kept going up, the builders needed stiffer springs to keep the valves and valve train under control and we kept having to redesign the tester to increase the maximum test pressure, in addition to accommodating the taller springs in use.

We had to go to 1200, then 1300 and now are at maximum of 1500 lbs of test pressure. A typical Pro Stock spring will now have around 450 lbs of seat pressure and a staggering 1400 lbs when the valve is fully open. Since the springs are taller than previous generation springs, they require a pretty large installed height of around 2.3".

The amazingly high rate of these springs means you could put one of the springs under each tire of a full size pickup truck and the springs wouldn't even be compressed all the way.

One issue that comes up though from making stiffer springs is that the spring weight itself becomes an increasingly significant part of the total weight of the valve train. The current springs are made taller to increase the spring rate, but this requires extra weight, and also requires a longer and thus heavier valve stem. This weight increase limits how far you can go with steel alloy valve springs.

To reduce this weight, titanium valve springs have been used in Pro Stock engines. Since they are so much lighter than steel springs, the weight reduction allows less spring force, so a typical titanium PS spring will have around 350 lbs of seat pressure and 1100 lbs of open pressure. The negatives on titanium springs are the high cost and the failure mode, when they fail they don't just lose pressure, they tend to fracture and come apart.

While mulling over that 1400 lb open pressure figure, keep in mind that at 10,500 RPM the valve and its spring is going through a complete open and close cycle of over 1" of lift almost 90 times per second. So in the time it takes to say "per second" thats around 100 complete cycles of this 1400 lb spring.

Its pretty amazing and impressive that working with engines and valve trains pushed this far to the limit that Pro Stock racing is so extremely competive, with the top teams often being within a few hundredths of each other on the track.

If you haven't seen one of the high speed videos of a valve spring at race RPM, take a look at:

PAC Racing - Multimedia

The wave motion of the spring coils up and down you see in the video are what are called "spring harmonics" and have to be carefully controlled to reduce undesired valve motion.

Paul Titchener
Power Technology

 

[Toejam]

Re: How high are PS engines winging now?

Is 4.90 still the Max Bore center for Pro stock? That must mean a 3.5" stroke(?) I'm guessing, but smaller stroke has to be paramount to those kinds of RPM's!

 

[NGNBLDR]

Re: How high are PS engines winging now?

Without necessarily quoting any particular post from above. I will try and touch on a few things that were mentioned. There’s a lot of stuff I can’t elaborate on for obvious reason. Unfortunately I can’t say what our piston to wall clearance is or what our head clearance is or even what RPM we leave at. I’d rather tell you I can’t say rather than lie to anyone. I don’t mind getting on these sites now and then to try and help people out. I was on “Mater” a long time ago and when it changed over I got away from it. Hopefully my “Post:#’s” will get a bit higher so I can get some credibility on here. Most of you already answered each others questions on here. RPM with an F1 engine are very high but the stroke is much less which equals out the piston speed. Pneumatic valve trains are the ultimate but will never be legal in Pro Stock. The success for high RPM’s in our applications has been the valve spring technology. It’s pretty simple, if you don’t have a spring that can support what you are trying to do. You probably can’t do it with any success. To be honest I really don’t know how much more RPM that these engines can handle. We are limited on bore spacing (4.900) and there has to be a stopping point sometime. A few years ago I would of said your nuts if you told me that we would be turning these things over 10k. Every day, month and year is a new learning curve for all of us out here. Who really knows what might happen even as little as a year from now. I agree with a post earlier, “It blows my mind that a 500 ci engine can spin that high and not toss it’s cookies out.” I often wonder that myself. That statement itself really plays out on the IHRA Pro Stock Engines. Talk about piston speed just look at those engines. Another post did ask if the pistons weighed around 400 grams. We do have minimum weights that NHRA has established for us. The pistons can’t weigh less than 460g, rods 480g, pins 135g, intake valve 90g and the exhaust valve 80g. I don’t know if I touch on everything but I look forward to being able to post on here every now and then.

Nick

 

[Paul]

Re: How high are PS engines winging now?

Nick, thanks for your comments on PS engines, I'm sure the members here would like to absorb as much as you can discuss without giving away secrets.

Paul Titchener

(Nick, also please check your Private Messages link here for a message from me)

 

[haagar]

Re: How high are PS engines winging now?

Then there is piston speed. F1 engines probably have less than half the stroke a 500 ci PS motor has so it can turn twice the RPM with the same piston speed.

An F1 engine is 152CI and the bore is right around 4 inches. I believe the last time I figured it out it worked out to a stroke of a little less than 1.5 inches.

 

[Bill]

Re: How high are PS engines winging now?

RE: "Pneumatic valve trains are the ultimate but will never be legal in Pro Stock." (bold type, mine)

For those of you who might not understand the significance of that statement, please consider this:

Formula I engines have not used metal valve springs for many years. Their "pneumatic" valve springs (compressed air, or "gas") are one reason they can run for hours on end at stratospheric rpm's without developing symptoms of valve train distress of various kinds. They can routinely run 20,000 rpm with no apparent problem.

I heard a rumor some time ago, that Warren Johnson had developed a compressed air valve spring at one time, but the rumor was unsubstantiated. I also heard that NHRA wouldn't allow it.

In fact, the NHRA Rulebook specifically disallows compressed air (pneumatic) valve springs on any car in competition, and has, for a while...

The burning question in MY mind is, since these current Pro Stock engines are rpm-dependent on horsepower production, and seem to have no end of problems with metal valve springs, why do they (NHRA) not allow such a system to be used? Can't be the cost factor...

You only have to buy them once.

 

[sdwarf36]

Re: How high are PS engines winging now?

Hopefully my “Post:#’s” will get a bit higher so I can get some credibility on here

LOL-- don't worry about that -this was a joke in reference to some doubters a while ago that thought post count was the only way to determine value of the info/rumor/Elvis sighting etc.

 

[Toby]

Re: How high are PS engines winging now?

He did build it. It was outlawed because MOPAR didn't want to race against it.

Check out the links below
F1 Engines _ Valve technology
http://www.billzilla.org/pneumaticvalves.gif

Toby Graham
DragTraction.Com

Warren Johnson had developed a compressed air valve spring at one time, but the rumor was unsubstantiated. I also heard that NHRA wouldn't allow it.

 

[Bill]

Re: How high are PS engines winging now?

Thanks, Toby, for giving some credence to the Warren Johnson rumor. And, thanks for the links.

I have no doubt that what you've said is true ("Mopar didn't want to race against it"), but it would seem to me that the guys who run the 10.000+ RPM alcohol-fired Hemis in TAD and TA/FC, which eat expensive valve springs at roughly the same rate that the Pro Stockers do, could benefit mightily from a long-life, pneumatic spring setup.

Are you saying that because Mopar didn't want to race against cars so equipped in Pro Stock, that NHRA banned them across the board?

That make no sense at all...

Seems to me, there's got to be more to this "ban" than that...

 

[Kelly]

Re: How high are PS engines winging now?

Hopefully my “Post:#’s” will get a bit higher so I can get some credibility on here

LOL-- don't worry about that -this was a joke in reference to some doubters a while ago that thought post count was the only way to determine value of the info/rumor/Elvis sighting etc.

heheh...the Mater Cred joke in it's essence and intended purpose!

 

[The Counterfeiter]

Re: How high are PS engines winging now?

I have no doubt that what you've said is true ("Mopar didn't want to race against it"), but it would seem to me that the guys who run the 10.000+ RPM alcohol-fired Hemis in TAD and TA/FC, which eat expensive valve springs at roughly the same rate that the Pro Stockers do, could benefit mightily from a long-life, pneumatic spring setup.

Interesting idea, but there might be a small rules problem and a big budget issue!
F1 ecus probably have as much computing power as the Space Shuttle - guaranteed to generate panic in NHRA Tech Department.
And . . . Ferrari's budget is $200,000,000 per car per year, requiring a huge sponsor (did ya ever wonder what those bar codes on Ferraris represent?).

It's fun to speculate, but reality quickly sets in! -

 

[Toby]

Re: How high are PS engines winging now?

The PVRS (pneumatic valve return system) is a dumb system, ie no computing power is required.

There is an outfit on the west coast making a bolt on PVRS and not a bad price either. I will try to find the link.

Toby Graham
DragTraction.Com

I have no doubt that what you've said is true ("Mopar didn't want to race against it"), but it would seem to me that the guys who run the 10.000+ RPM alcohol-fired Hemis in TAD and TA/FC, which eat expensive valve springs at roughly the same rate that the Pro Stockers do, could benefit mightily from a long-life, pneumatic spring setup.

Interesting idea, but there might be a small rules problem and a big budget issue!
F1 ecus probably have as much computing power as the Space Shuttle - guaranteed to generate panic in NHRA Tech Department.
And . . . Ferrari's budget is $200,000,000 per car per year, requiring a huge sponsor (did ya ever wonder what those bar codes on Ferraris represent?).

It's fun to speculate, but reality quickly sets in! -

 

[Nick Name]

Re: How high are PS engines winging now?

The drag on the crank from too heavy valve springs is a necessary evil to keep from scattering the motor. Imagine an engine with PVA that you could run at peak power on the dyno, then dial down the pressure and watch the power go up until the valves won't close properly, then dial it back up just a bit and it is set. Only enough drag on the timing gear to get the job done and not a bit more.

 

[Bill]

Re: How high are PS engines winging now?

Good idea, Jay; you could run variable, RPM-related pressure in the pneumatic "spring" that would rise with the rpm's... less pressure at lower rpm's when less pressure is sufficient to keep the lifters on the cam lobes...

A digital module could monitor the rpm's and feed the information to a simple pressure regulator that would let the springs have what they needed for any given rpm, then bleed it off when the rpm's come back down after a shift.

Probably would be worth some horsepower at the crank... do ya think???

 

[Nick Name]

Re: How high are PS engines winging now?

Yep, just staying slightly ahead of what the motor needs and not a bit more.

 

[Bill]

Re: How high are PS engines winging now?

So, with all the potential advantages of this system, why would you think NHRA would see fit to ban the use of it, across the board?

Initial cost could be expensive, but with it, you'd virtually never have to buy another valve spring. Ultimately, it would be a cost-saving measure, it would seem.

That's why Nick Ferri's comment, "Pneumatic valve trains are the ultimate but will never be legal in Pro Stock." is puzzling to me.

Doesn't NHRA contend that they try to keep the cost of racing down?

This would seeem to be just such an opportunity.... but, it's banned.

I wonder why?

 

[DaveRenk]

Re: How high are PS engines winging now?

OK, we just fixed the valve train limit with the air springs....What is the next limit we need to address? My guess would be the size of the carbs or ???

 

[Bill]

Re: How high are PS engines winging now?

Can't fix it if NHRA won't allow it... lol!

One thing at a time!

But, Electronic Fuel Injection might be the next step; Detroit hasn't built a car with a carburetor on it for a lot of years.... but, NHRA keeps these huge hood scoops and antiquated carburetor systems (which, though antiquated, may match the EFI for output) in spite of a loudly-ticking clock...

I don't think anybody can deny that Pro Stock has stagnated, technologically, through no fault of the racers. Legislated to death, it's a minor miracle that these cars are as blindingly fast as they are.... a tribute to the mechanical geniuses who make them perform way beyond what you'd expect, given their considerable limitations.