32 replies to this topic

[Canuck]

Reading the June/July issue of RET (late thanks to the Canada Post strike which otherwise affected only internetless grandparents and junk mail senders) and can't help but run the numbers on the latest Sonny Leonard 16.5 litre drag engine. According to RET, it breaks down as follows:
5.220" bore
5.875" stroke
8200 RPM
17:1 compression ratio
2200 hp

There's a number of things that jump out at me - the obscene (imaginary?) piston speed of 41 m/s being the largest, BMEP surpassing NASCAR (if one assumes the 2200hp occurs at peak rpm) despite the ludicrous bore size, the compression ratio with that bore size...

I know it doesn't need to last long but 41m/s with a 5.22" diameter piston on an 8" rod? Really? REALLY? I'm wrong often enough to be open-minded about it, but sitting firmly in the "marketing bullshit" camp. If Mercedes/McLaren and their AlBeMet rods allowed the use of a longer stroke and smaller bore, which allowed for better breathing and better mid-range performance, how on earth are SRE supposed to pull a huge BMEP out of such a massive bore? More, how are they managing a 17:1 comp ratio?

[Bob Riebe]

I put his under the V8 thread in the nostalgia section, but I'll add it here.

Sonny Leonard, current king of mountain motors has taken them one step farther.
There are engine with 5.20, then 5.30- now Sonny's latest has 5.40 bore centers.


I just got the newest Hot Rod magazine with an article on the now production engine, but I cannot put a picture up.
It does look slightly different from the older engines as it has a bigger block. Standard small size will be 940 in. cu., but the first built for the gent who paid for the developement is 1005 in. cu. with a 5.22 bore by a 5.87 stroke.

Here is part of an article when he was working on it.

“...I believed back in those days that engines could only get about 540 or 550 tops,” he admitted. “Those were mountains back then but in today’s world, they are effectively molehills.”

Back in those days the leading proponents of the massive displacement engines were not only Leonard, but Pat Musi and the legendary “General” Lee Edwards.

As overwhelming as the 1005 cubic inch engine is, Leonard isn’t naive enough to believe that it’s the end all of engine displacements. He definitely sees even larger on the horizon with the continual refinement of the technology.

“It takes two things, time and money,” admits Leonard. “If we could put a man on the moon and bring him back over 40 years ago, anything is possible.”

The general consensus amongst engine builders is that the larger the displacement, the less efficient it will be. For instance, Leonard believes an engine displacing in the range of 500 inches will more times than not be more efficient than one displacing twice as many cubic inches.

However, for brute horsepower in a car weighing 2350 pounds, size does matter. And truth be known, the outer dimensions on the 1005-incher will be the same as the 904-inch beast he completed last year.

“This engine is capable of running 8,000 rpm which was unheard of five years ago,” Leonard explained. “The door is open here. It might not be as efficient but it will go quicker. If it was weight per cubic inch, this wouldn’t be the way to go.”

Leonard is building this monstrous powerplant for Craig Olson and his CEO Racing team sponsored by Rescue Voice.

According to Leonard, the engine will be naturally aspirated and feature Sonny’s Racing Engines new fully in-house CNC-ported special Edition GM Hemispherical Cylinder Heads.

The heads on this 2150 horse engine will feature Sonny’s Ultimate Pro Stock porting. Other engine components includes SAR custom titanium valves, PSI springs, Sonny Bryant billet crankshaft, GRP billet aluminum rods, mammoth SAR/ custom pistons with special ring package, SAR/CE 1.062 keyed lifters, 1.031 tool steel taper-wall pins, SAR/T&D.

The mega-inch engine will also feature a Jesel shaft mounted rocker system, Jesel belt drive, Custom Dailey 7 stage lightweight dry sump oiling system, ATI balancer, MSD Ignition, SAR sheet-metal Pro Stock intake featuring SAR/ Accufab Throttle Bodies.

The engine will be equipped with a custom Big Stuff electronic fuel injection system, a set of billet valve covers from Moroso and an MSD Pro Series Starter.

The engine is based on a special SAR billet aluminum block with a 2-inch raised cam to accommodate the custom 70 mm camshaft.

Leonard estimates the engine will weigh about 675 pounds with an EFI system. The average 500-inch engine typically weighs in the 550 pound range.

“It will catch a lot of eyes and it will go plenty fast,” Leonard added.

Edited by Bob Riebe, 24 July 2011 - 05:07.

[Canuck]

So - what advancement has allowed the massive increase in piston speed?

(interesting to note that the Hotrod article seems to have more specific specs as opposed to the RET article)

[Magoo]

So - what advancement has allowed the massive increase in piston speed?

Running the engine eight seconds at a time, the classic piston speed limits don't apply, at least not in the same way. Once again, the critical factor is not mean speed but acceleration. This monster has a 5.8-in. stroke, but it also has an 8-in connecting rod so it's not as outlandish as it might look.

[cheapracer]

I know it doesn't need to last long but 41m/s with a 5.22" diameter piston on an 8" rod?

As Magoo points to the rod length has bearing on the acceleration and deceleration of the piston which is more important than the average piston speed.

"Piston speed" is a bit of a misnomer and a guide only as it's never doing one speed and of course is stopping and starting twice per 360 degrees and a longer rod effects gentler stops and starts as well as shorter dwell allowing higher compression ratios.

[Canuck]

Yes, I'm aware that it's a "mean" piston speed with stop/startconditions and no real period of constant velocity. Still, it's a been a bit of a benchmark in the past as mean piston speed hasn't really climbed much in the past couple of decades - much like BMEP. Of course we're increasing the speed at which those BMEP figures are beig achieved, which says a lot but 16ish bar is still fairly reliable as a max figure.

I'm on holidays and away from my spreadsheet-o-formulas - very much looking forward to plotting that acceleration curve.

[Magoo]

(interesting to note that the Hotrod article seems to have more specific specs as opposed to the RET article)

In this same (current) issue of HRM there is also a decent (I think) story on the Katech-Motus V4 engine, in case anyone is interested. (It's a sort of 3/4-scale V4 version of a GM LS V8 with a big bang firing order, GDI, and other neat wrinkles.) There did seem to be some interest in this engine here in a previous thread. It's a sort of walk alongside the engine over its journey from the drawing board to production.

[WPT]

....and a longer rod effects gentler stops and starts as well as shorter dwell allowing higher compression ratios.

A longer rod, other factors being equal, will reduce the piston acceleration at TDC. This will increase the dwell time at TDC, not shorten it. WPT

[TDIMeister]

Nevertheless, 8/5.8=1.38. The only lower L/R ratio I've ever seen is 1.36 here: http://users.erols.c...ss/tablersn.htm

Piston acceleration at TDC induced by secondary motion is very high and peak piston velocity occurs at an earlier crank angle after TDC.

Edited by TDIMeister, 27 July 2011 - 01:41.

[cheapracer]

A longer rod, other factors being equal, will reduce the piston acceleration at TDC. This will increase the dwell time at TDC, not shorten it. WPT

Yes you are correct, I blame Tony.

[gruntguru]

. . . . and . . . . . after all the fuss, it seems 8" is actually a very short rod. Thanks TDI for pointing that out.

[Canuck]

The acceleration is not as high as the 20k rpm F1 V8s however, it's velocity is considerably higher and one would have to assume that a 5.22" piston is going to generate enormous forces compared to the F1 engine's. I wonder how much that piston/pin combo weighs.

Edited by Canuck, 27 July 2011 - 05:07.

[Tony Matthews]

Yes you are correct, I blame Tony.

Guilty, your Honour. No, wait a minute, I blame grunt.

[Magoo]

Nevertheless, 8/5.8=1.38. The only lower L/R ratio I've ever seen is 1.36 here: http://users.erols.c...ss/tablersn.htm

Those are all stock production engines. Sonny's engine is based on BBC stroker motor architecture and experience. Sonny and a few other builders have been doing these outlandish combinations for some years now (aka "mountain motors") and each year they get incrementally larger in displacement. This latest engine exceeds 1,000 ci, hence all the to-do. The latest billet block employs a taller deck height and greater bore spacing, which allows a longer rod and a better bore/stroke ratio than some previous engines.

Edited by Magoo, 27 July 2011 - 08:37.

[TDIMeister]

The acceleration is not as high as the 20k rpm F1 V8s however, it's velocity is considerably higher and one would have to assume that a 5.22" piston is going to generate enormous forces compared to the F1 engine's. I wonder how much that piston/pin combo weighs.

When I have some time I will calculate the value of the acceleration, but based on an extrapolation from Jack Kane's comparison of a Cup engine and an F1 one, I would disagree that the acceleration of such a motor is not as high as a 20k RPM F1 V8 - as you well know, RPM is not the only factor. Acceleration being only the time rate of change of velocity, if you have a high velocity and you go between this high velocity to zero twice per cycle at a given RPM, the acceleration is going to be higher, period.

I calculate 14.56 bar BMEP assuming 2200 HP @ 8200 RPM and 16.48 L displacement. Pretty impressive, considering the FMEP from the high side-thrust loads of the low A/R geometry, high bearing loads from the 17:1 compression, and the tribological issues of the sky-high piston speed. While still impressive, it's interesting to note that while you can break the rules of mean piston speed 8 seconds at a time, the BMEP boundary of NA engines has not been breached.

Those are all stock production engines. Sonny's engine is based on BBC stroker motor architecture and experience. Sonny and a few other builders have been doing these outlandish combinations for some years now (aka "mountain motors") and each year they get incrementally larger in displacement. This latest engine exceeds 1,000 ci, hence all the to-do. The latest billet block employs a taller deck height and greater bore spacing, which allows a longer rod and a better bore/stroke ratio than some previous engines.

Thanks Magoo. Yes, I know this engine is not based on any production parts. Nevertheless, the value of the L/R ratio is very small. But kudos to the builder for going against the grain of typical practice for building an impressive spec sheet. I know that more than 8 cylinders in a cross-plane crank, 90° vee layout is anathema for North American drag racers, but I've been thinking about designing and building a V12 turbodiesel drag engine based on 2 Cummins cylinder heads on a common bespoke billet block and crankshaft using widely available aftermarket Cummins reciprocating components.

[mariner]

“It takes two things, time and money,” admits Leonard. “If we could put a man on the moon and bring him back over 40 years ago, anything is possible.”

Well said,Sonny - you here so much about "can't" these days that saying it IS possible ( albeit with time and money) is refreshing.

[TDIMeister]

Let's put that thinking into time- and intergalactic travel...

[WPT]

When I have some time I will calculate the value of the acceleration

For acceleration at TDC use: a=rw^2(1+r/l) where r is crank throw radius, (l) is length of rod ( center to center), and (w) is rotational speed in radians per second. WPT

[cheapracer]

I've been thinking about designing and building a V12 turbodiesel drag engine based on 2 Cummins cylinder heads on a common bespoke billet block and crankshaft using widely available aftermarket Cummins reciprocating components.

Alibaba and China are your friends ... (and possibly Tatra!)

http://www.alibaba.c...h...ct_en&fsb=y

[TDIMeister]

Interesting find, thank you.

[Magoo]

I know that more than 8 cylinders in a cross-plane crank, 90° vee layout is anathema for North American drag racers, but I've been thinking about designing and building a V12 turbodiesel drag engine based on 2 Cummins cylinder heads on a common bespoke billet block and crankshaft using widely available aftermarket Cummins reciprocating components.

These giant V8s are popular in American drag racing because the prevailing rulebooks for their categories (Pro Stock and Pro Mod, essentially) state "maximum 8 cylinders." Your V12 Cummins sounds like fun. Here in the states the Cummins is the SBC of diesels and parts are ubiquitous.

[Canuck]

When I have some time I will calculate the value of the acceleration, but based on an extrapolation from Jack Kane's comparison of a Cup engine and an F1 one, I would disagree that the acceleration of such a motor is not as high as a 20k RPM F1 V8 - as you well know, RPM is not the only factor. Acceleration being only the time rate of change of velocity, if you have a high velocity and you go between this high velocity to zero twice per cycle at a given RPM, the acceleration is going to be higher, period.

Entirely possible I made a mistake - I used Kane's F1 engine specs and my curves matched his, which led to the supposition that my SRE curves were also accurate. I was surprised to see the variance but it was well past my nap time when I finished so I didn't bother to hash it out or post my results. I disagree with the last sentence though - if you look at Kane's chart, you'll see that the F1 has higher accelerations but lower peak velocities.
(Apologies to Jack for the hot-linked image - firewall prevents me from re-hosting the image)

[Lee Nicolle]

. . . . and . . . . . after all the fuss, it seems 8" is actually a very short rod. Thanks TDI for pointing that out.

I was thinking that too, all these very large [for me] numbers but it did not really seem in context
But after all said and done really while some interesting mechanical exercise these engines should at least be based on standard dimension hardware by the rules. Standard bore spacing, cam location and maybe even deckheight. Which should bring the costs down somewhat.
That should not preclude aftermarket blocks though but recogisable Chevs, Fords, Mopars and whatever can be found that works.

[Canuck]

That's NHRA. Pro-Mod is IHRA where you can run 1000 cubic inch engines. Sounds preposterous to type that. I'm not sure of an NHRA class that allows more than 500ci including TF.

[bigleagueslider]

The actual kinematics of this particular engine (piston diameter, stroke length, rod ratio, mean piston velocity, piston accelerations, etc.) are not so important. What really matters with this very limited life drag motor is the actual number and magnitude of the conrod load cycles. Even running at 8500 rpm, this engine's conrod would accumulate fewer than 10^5 fatigue load cycles during a single run. Such a low number of fatigue load cycles would permit a high conrod stress level to be used. An F1 engine running at 18,000 rpm, even with much lower piston accelerations/velocities, would use a far greater percentage of its available fatigue life cycle in just a few minutes.

As for its claimed BMEP rate, it's within the range one would expect from a high performance N/A engine like in F1.

[WPT]

The calculated max piston acceleration of the 1005 ci drag engine at 8200 RPM is 7670g. WPT

[Canuck]

The SRE engine has significantly higher velocity than the F1 piston, 68 m/s vs. 42 m/s, yet drastically lower acceleration. It's "short" rod / small L/S shows up in the double-hump deceleration.

[Magoo]

Personally, I think the 2.900-in. intake valve is sort of interesting.

[Canuck]

Tea saucer on a broomstick. You understand my incredulity, the disbelief in my initial post. Everything about this engine is enormous - absurdly large (okay the rod length is only half and inch longer than the gazillion Harleys out there) and despite being a caricature of a "normal" engine, by all of the normal performance measures - BMEP, hp / unit displacement, MPS - it's no slouch either. Clearly it suffers due to its size but it still measures admirably.

[TDIMeister]

Follow up: my own spreadsheet gives results in mm/deg and mm/deg^2 and from that standpoint, my statement is correct:

Acceleration being only the time rate of change of velocity, if you have a high velocity and you go between this high velocity to zero twice per cycle at a given RPM, the acceleration is going to be higher, period.

However, I neglected to consider the effect of RPM, which increases the acceleration by the square. That's my bad. On this, the F1 engine @ ~20k RPM does see substantially higher g's than the Cup engine @9k RPM, with the SRE engine @8.2k RPM in between (my numbers also agree with those already reported @ 7670 g).

Nevertheless, forces are more relevant than accelerations, in being that F=m*a, the SRE engine - on the assumption that reciprocating components would be at least as heavy as Cup counterparts - would see pin-eye, crankpin and rod tensile loads that far exceed either engine compared by Kane. But, 8 seconds at a time (only about 1000 revolutions of the crankshaft from green light to the end of the 1/4 mile!), many rules go out the window, e.g. the aluminum con rods.

Edited by TDIMeister, 30 July 2011 - 14:34.

[bigleagueslider]

Follow up: my own spreadsheet gives results in mm/deg and mm/deg^2 and from that standpoint, my statement is correct:
However, I neglected to consider the effect of RPM, which increases the acceleration by the square. That's my bad. On this, the F1 engine @ ~20k RPM does see substantially higher g's than the Cup engine @9k RPM, with the SRE engine @8.2k RPM in between (my numbers also agree with those already reported @ 7670 g).
Nevertheless, forces are more relevant than accelerations, in being that F=m*a, the SRE engine - on the assumption that reciprocating components would be at least as heavy as Cup counterparts - would see pin-eye, crankpin and rod tensile loads that far exceed either engine compared by Kane. But, 8 seconds at a time (only about 1000 revolutions of the crankshaft from green light to the end of the 1/4 mile!), many rules go out the window, e.g. the aluminum con rods.

TDIMeister,

With regards to rod fatigue life, you are partially correct that forces are relevant. But more importantly, what matters is the number of load cycles (N), the magnitude and direction of the applied loads ®, and the total combined stresses (tension/compression/torsion/shear). As I previously noted, a Ti drag race rod that is subject to 10^5 load cycles can have a working stress level almost double that of a Ti F1 rod that is subject to 10^7 load cycles. Take a look at an S-N or Goodman diagram for alloy steel or titanium.

slider

[gruntguru]

Ahhh the good old days of qualifying engines in F1.

[TDIMeister]

With regards to rod fatigue life, you are partially correct that forces are relevant. But more importantly, what matters is the number of load cycles (N), the magnitude and direction of the applied loads ®, and the total combined stresses (tension/compression/torsion/shear). As I previously noted, a Ti drag race rod that is subject to 10^5 load cycles can have a working stress level almost double that of a Ti F1 rod that is subject to 10^7 load cycles. Take a look at an S-N or Goodman diagram for alloy steel or titanium.

Yes I am well aware of that. That's why I qualified my post by stating that an 8 second run represents only about 1000 crankshaft revolutions. If you don't need infinite life out of a set of rods, aluminum is a fine lightweight alternative and you can load the rods relatively higher at few cycles.