http://www.enginelab...ingy-on-details
The are going to be some very expensive carburettors out there for sale cheap.
Posted 28 July 2015 - 16:55
http://www.enginelab...ingy-on-details
The are going to be some very expensive carburettors out there for sale cheap.
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Posted 28 July 2015 - 18:04
I assume they mandated carbs previously which is stupid cubed, so now they do merely stupid and mandate EFI and gratuitously obsolete a bunch of expensive gear. People who write technical regulations don't generally seem very bright, I suppose getting into that position in typical organizational manner is 90% political rather than based on actual merit.
Posted 28 July 2015 - 19:25
If you read the article the switch to injection does not bother them that much, they had to have two sets of carbs., one for the dyno and one for the track.
What they find stupid is the new 10,500 rpm rev. limit.
Posted 28 July 2015 - 20:01
To be fair, I know this is the top level but those sort of engine speeds on such a big engine on gas are insane.
The top teams according to that article are pushing 11500 rpm which is uuterly ridiculous for such an engine.
If grids are starting to fall, then I do not blame the governing body trying to do something.
Engine speeds are relatively easy to police and easy to govern, EF isnt though, unless theya re pushing for a spec ECU
Posted 28 July 2015 - 22:55
Yep, TC/LC stuff begins to get a lot harder to scrutineer against with more electronics.
Posted 28 July 2015 - 23:47
What is with the EFI,, a throttle body injection is 80s technology. And for a racing engine probably less reliable and harder to tune than the carbs. For street use EFI is better,driveability and possibly economy though realistically not much better than a good carb on older engines. none of which is a concern on a pro Stock!
This will make the car counts smaller, not larger. Though the cars look so out of synch with a production car anyway. They really border on being funny cars!
Production based cars and engines is in the long term the way forward. With probably a 400ci limit [or less] And then maybe an 8500 limit.
Making shorter wheelie bars will at least short term cause some accidents as the cars unhook and go into the wall, or the other car. Less power and unhook the cars with shorter 4 links and even smaller tyres will put more emphasis on the driver.
Posted 29 July 2015 - 03:05
One benefit of EFI is more consistent control of fuel mixtures, which should help with reliability. But I can't imagine the EFI system needed for a PS car is an off-the-shelf item.
Posted 30 July 2015 - 01:58
The term "throttle body injection" is a bit of a misnomer. Actually, the system is sequential port fuel with ganged throttle body and plenum -- much like the NASCAR system but 8V. Maintains the current intake manifold technology more or less.
Some Pro Stock engine builders have been using EFI on the dyno for some time. Allows much easier baseline setup and eliminates a number of tricky variables. They dial everything in, then bolt on the carbs and duplicate the calibration.
Posted 19 August 2015 - 16:55
Some more info/thoughts on Pro Stock going EFI
http://www.enginelab...stock-efi-rules
No more huge scopps!
The hardware rules seem quite logical - I love the 25 sq. ins. throttle body - F3 eat your heart out.
Posted 20 August 2015 - 02:41
No kidding. That 25 sq.in. throttle body is awesome!
Posted 28 August 2015 - 00:50
No kidding. That 25 sq.in. throttle body is awesome!
I guess it must work. It just looks wrong! 4 or 8 smaller ones with the same total area too me would be more efficient.
Most race style injection set ups use multiple throttle bodies, road cars use for the most part one as it is cheaper, and probably easier to tune for low end torque and fuel economy.
I think I am correct in that Nascar still use a 4 bbl throttle plate?
Posted 03 September 2015 - 18:03
some more stuff from the great Enginelabs website. Thye have very eclectic range of articles and its nice to see what goes on outside the world of F1.
3,000 bhp at 8,200rpm and a very interesting noise.
http://www.enginelab...000-horsepower/
To make the point about being eclectic this my favourite from 100 yrs ago.
http://www.enginelab...tone-oil-engine
Such a soothing sound, could be put on prescription for excess stress.
The website also has an article on the latest 500,000 lb thrust engine for NASA quoting that as equal to 12 million bhp. I'm never sure about thrust to bhp as I think it depends on alltitude etc. but IRCC correctly the biggest rocket engine of all time was the Rocketdyne F-1 , five of which powered the Saturn V Apollo launch rocket. IF the 12 mililon bhp for 500,000lb thrust is correct (?) then Saturn had 180 milion bhp??
Posted 04 September 2015 - 00:51
https://upload.wikim...eleration_2.svg
Nice acceleration plot for Saturn V. One of the stage 1 engines gets switched off at point 2 on the graph - to limit acceleration! Acceleration gets out of hand as the mass of the vehicle rapidly reduces during fuel burn.
Posted 04 September 2015 - 03:45
The Rocketdyne F-1 engine produced around 1.5 million pounds of thrust and used kerosene (RP-1) fuel and liquid oxygen. The RS-25 (SSME) produces around 420,000 pounds of thrust at SLS and uses LH2 fuel and liquid oxygen. The most recent NASA rocket engine is the RS-68 which produces over 600,00 lbs of thrust at SLS and uses LH2 fuel and liquid oxygen.
One main reason for using liquid engines is because they can be throttled during launch. When the rocket is still flying within the atmosphere its speed is kept below mach 1 to minimize aero loads on the fairing.
Posted 04 September 2015 - 07:41
" within the atmosphere its speed is kept below mach 1 t"
Nah, it easily exceeds mach 1. The limiting speed is at the max Q point, which is the dynamic pressure, a function of Cd (which varies with speed) density (which varies with altitude) and speed. M1 is roughly300-400 m/s right the way up til 100000 m, it is exactly given by sqrt (gamma *R*T) , as per this page https://www.grc.nasa.../BGH/sound.html
and you need to know T vs altitude, which is given by the NASA statndard atmosphere model
The following shows apollo 11 at roughly M2 only 10 miles up
Edited by Greg Locock, 04 September 2015 - 08:38.
Posted 04 September 2015 - 07:50
I'm old enough to remember hearing the Apollo 11 moon landing on a transistor radio in a pub garden and I did once catch a very poor glimpse of a Shuttle launch havng got up at a very silly hour to drive to see it.
To my simple mind those Apollo/Saturn missions remain the greatest engineering adventure ever. The way all that design and complexity becomes sheer power is awesome.
Posted 05 September 2015 - 07:59
Mach 1 in Greg's video is at around T+1 minute. At T+1:05 you can see (I think) a shock wave forming at the top of the first stage booster and sliding down the vehicle as its speed increases.
Posted 07 September 2015 - 23:22
The F1(B) engine is being considered as liquid fuel boosters for the later block SLS launches. They've got an advantage in terms of specific impulse and they could be throttled to minimize aerodynamic loads unlike solid boosters. Adding four liquid fuel engines adds a ton of cost and points of failure though.
Posted 08 September 2015 - 03:07
GL- thanks for the correction regarding mach 1 vs max Q for the limit of rocket launch velocity within the atmosphere.
C_D- Four RS-25's are used for the center 1st stage of the initial SLS vehicle, along with a pair of 25% longer SRB's. Most of the thrust comes from the SRB's. The reason SRB's are used is because they present less difficulty at launch. Cryogenic liquid propellants must be loaded just prior to launch, and if the launch is scrubbed at the last minute (which happens quite often) the liquid propellants must immediately be drained.
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Posted 08 September 2015 - 23:43
Ah. Last I'd heard NASA was still evaluating the Rocketdyne proposal for the Block 2 boosters. The nostalgic side of me thinks that's a bummer.
Posted 13 September 2015 - 12:04
I guess it must work. It just looks wrong! 4 or 8 smaller ones with the same total area too me would be more efficient.
Most race style injection set ups use multiple throttle bodies, road cars use for the most part one as it is cheaper, and probably easier to tune for low end torque and fuel economy.
I think I am correct in that Nascar still use a 4 bbl throttle plate?
Yes, that is the NASCAR setup. Originally I was told that NHRA Pro Stock was going to use a pair of similar throttle bodies, but that turned out to be old info.
Posted 13 September 2015 - 22:55
Lee. For steady flow, one large duct will always flow more than several smaller ones with the same total cross sectional area.
Posted 25 September 2015 - 11:21
Getting back on Topic. A big reason for going EFI is cost. Pro Stock teams have a LOT more than a couple of sets of carbs for the Dyno and Track. And each carburator costs well in excess of $5,000.
Warren Johnston did an article for Speed TV where they showed the rows of Holley carbs back in his Trailer... each one pre-jetted for different atmospheric conditions. At the time ( early 2000's ) he stated that he had $150,000+ of carbs hanging on the walls . And double that amount back at the shop. They only took what was required on that " Leg " of the schedule .Obviously if they were running in Denver he would not be taking carbs set-up for New England. Each carburator was pre-set for specific atmospheric conditions. If the Barometrc pressure or grains of water change even minutely, carburators have to be re-jetted and re-configured when you are at the Pro Stock level. It is far faster and more accurate to have extra carbs pre-set for the conditions than to be constantly adjsuting them. The West Coast swing was apparently one of the Major headaches. From the heat of Sonoma, to the low density altitudes of Denver then on to Seattle where it could be 50 F in the morning with air density below Sea level, to afternoon runs in the mid to high 80's with a 3,000 ft difference in Air Density from the morning.
With EFI all of that is eliminated. You can have one or two set of hardware and make changes with a simple keystroke. Atmospheric changes can be handled easily and automatically with the programing and sensors. Adjusting for atomospheric and traction changes is far easier with EFI and in the long run less costly.
Nascar has noted similar benefits from it's EFI program. And BTW... thre are some REALLY good deals on Nascar used carbs if you know who to contact. The Road Racing carbs are simply amazing.
Posted 03 October 2015 - 03:39
Slightly off topic, again, but somewhat related to the above about a single throttle body vs several.
I've always been curious why the BME top fuelers use the snorkel style scoop over the bird catcher style. There are no visible butterflies but obviously they're metering air somehow.
My first thought was that it's just cheaper than buying someone else's blower hat. BME is a machine shop, it's easy to machine some rectangles and build a throttle body. Then I noticed that the butterflies seem set different front to rear. Could they be using the butterflies to tune the front to rear distribution of boost? Setting the blowers back has fixed most of the problem but maybe there's some adjusting to be done for a given blower?
Posted 03 October 2015 - 11:15
Slightly off topic, again, but somewhat related to the above about a single throttle body vs several.
I've always been curious why the BME top fuelers use the snorkel style scoop over the bird catcher style. There are no visible butterflies but obviously they're metering air somehow.
My first thought was that it's just cheaper than buying someone else's blower hat. BME is a machine shop, it's easy to machine some rectangles and build a throttle body. Then I noticed that the butterflies seem set different front to rear. Could they be using the butterflies to tune the front to rear distribution of boost? Setting the blowers back has fixed most of the problem but maybe there's some adjusting to be done for a given blower?
NHRA limit for throttle body area is 65 square inches in any event, so...
Edited by Magoo, 03 October 2015 - 11:16.
Posted 04 October 2015 - 03:09
There are no visible butterflies but obviously they're metering air somehow.
I can see four rectangular butterflies in your photo but perhaps you were referring to something else?
Posted 04 October 2015 - 05:34
Posted 05 October 2015 - 02:36
There is quite a large volume of air inside the scoop. The scoop does not do much at low speed, so moving the throttle plates from the scoop inlet to just ahead of the supercharger should make a difference in response of the engine.
Posted 06 October 2015 - 05:02
Yes, possibly as much as two revolutions worth of air in there.
Posted 15 February 2016 - 05:17
Winter Nats are in the books, looks like Pro Stock lost about 1/10 compared to last year, well within the range that conditions could account for.
Still don't really understand why they don't just allow OHC heads. If the valvetrain is such a drain on the parts budget and manpower just eliminate a huge chunk of it. Blocks and heads are already purpose built, with a 1-2 year lead time the manufacturers could easily incorporate the change in their next gen designs.
Let top fuel do the same too. A guy like Gary Densham might have a spare car if he weren't paying a mechanic all year every year just to service the valvetrain.
Posted 15 February 2016 - 14:41
2 questions:Still don't really understand why they don't just allow OHC heads. If the valvetrain is such a drain on the parts budget and manpower just eliminate a huge chunk of it. Blocks and heads are already purpose built, with a 1-2 year lead time the manufacturers could easily incorporate the change in their next gen designs.
Let top fuel do the same too. A guy like Gary Densham might have a spare car if he weren't paying a mechanic all year every year just to service the valvetrain.
Posted 16 February 2016 - 02:57
2 questions:
- what mechanic makes the equivalent cost of a spare TF car?
- how does going to OHC eliminate that person's job? Seems to be implying that those costs are due to lifters and pushrods.
Bonus question: what do top fuel cylinder heads have to do with PS injection?
1. Some crew chiefs maybe? I wasn't suggesting that a mechanic earns a salary equal to the cost of a car in one season, which is why I mentioned the fact that he's paying a guy every year to work on valvetrain. The big teams would just spend any saved money to go testing or other R&D but a small team pocketing thousands of dollars per year can make a difference. Again, Gary Densham has been doing this for decades and is now probably done racing after his crash this weekend.
2. Because nobody has to service a large portion of the existing valvetrain between rounds? Why would teams keep a guy around when their job is unnecessary? The 45 minute turnaround means that you basically have a mechanic for everything, including valvetrain. Moving to OHC would mean just means that the cylinder head guys bolt in some cams and loop a timing chain around them after the heads go on, no need for another mechanic.
3. I wasn't making a connection between them, I'm sorry if it seemed that way. They were separate thoughts, though linked by the fact that pushrod engines are, in general, somewhat cumbersome to service and add several points of failure that OHC doesn't have to worry about.
It's entirely possible that I'm an idiot but given what teams and engine builders spend on parts I would think that the savings would outweigh the added investment in new **** over time.
Anyway, the racing was decent so far this year. Lots of fuel races decided by less than a car length
Posted 20 February 2016 - 05:53
The 2V pushrod V8 engines in TF/FC/PS NHRA drag racing are still used for a couple reasons. First, these engines have a long history with the NHRA that their fan base connects with. Second, these engines provide more than enough performance to please the fan base, at a reasonable cost to the race teams. As for the effort required from the mechanics to service one of these engines between rounds, if you've ever been in the pits of an NHRA race you'd have seen how quickly the mechanics can strip down and re-assemble a TF or FC engine. The work is usually performed without removing the cylinder block from the chassis.
Posted 20 February 2016 - 06:48
I don't at all disagree that they do the job quickly but it would seem that this is so because of the amount of preparation that takes place before and during a race weekend. The rocker assemblies are pre-built but someone back at the shop or in the hauler during the weekend has to assemble, inspect and repair them.
Posted 20 February 2016 - 16:25
Posted 21 February 2016 - 02:52
In reality valve actuation means little difference in power in a race engine. Chamber shape, valve location and size is the important feature.
OHC have the enldess problem with chains or belts. Those types of engine would use gears.
The service between runs would be longer too. As would the spares as you would have to have the cam/s as part of a head assembly if you torch one.
Posted 21 February 2016 - 11:45
Sainty Engineering from Sydney had a TF engine that was entirely built by them. The valve actuation was by SOHC - two intake valves and one exhaust valve. The thing that interested me most about the valve gear was that it was based on the E-series Falcon six-cylinder engines. The camshaft, rockers etc. looked very much like the Ford parts (the Ford valve system was, I think, designed by INA and in turn was based on a Mercedes design). I actually talked to Norm Sainty and he claimed that OHC had been banned in the US because they were worried it would take over from "traditional" V8 engines. He also claimed that Sainty Engineering was the first to use the all Al "billet" engine. Norm claimed the opposite happened with the billet engine in the US and all TF engine were soon legislated to be "billet".
Edited by Kelpiecross, 21 February 2016 - 11:48.
Posted 23 February 2016 - 03:31
I don't at all disagree that they do the job quickly but it would seem that this is so because of the amount of preparation that takes place before and during a race weekend. The rocker assemblies are pre-built but someone back at the shop or in the hauler during the weekend has to assemble, inspect and repair them.
That is a great point. If you watch that video of a 7 or 8 man crew tearing down an NHRA TF drag engine between rounds, you'll note that they had the blower/intake manifold/throttle/scoop assembly off the engine in around 2 minutes. They had the valve covers and rocker assemblies off in just over 2 minutes. And they had the cylinder heads off in around 3 minutes. Especially impressive was the guy underneath the car that appeared to have removed several main bearing caps before the video ended.
As you noted, this rapid rebuild of a TF or FC engine is made possible by having subsystems that are prepared and ready to be installed. But it is not much different than what teams do in endurance racing at LeMans or Daytona.
Posted 23 February 2016 - 08:41
Sainty Engineering from Sydney had a TF engine that was entirely built by them. The valve actuation was by SOHC - two intake valves and one exhaust valve. The thing that interested me most about the valve gear was that it was based on the E-series Falcon six-cylinder engines. The camshaft, rockers etc. looked very much like the Ford parts (the Ford valve system was, I think, designed by INA and in turn was based on a Mercedes design). I actually talked to Norm Sainty and he claimed that OHC had been banned in the US because they were worried it would take over from "traditional" V8 engines. He also claimed that Sainty Engineering was the first to use the all Al "billet" engine. Norm claimed the opposite happened with the billet engine in the US and all TF engine were soon legislated to be "billet".
Not knocking the Saintys as they have done a very good job on a budget but it really has never out performed any 'normal' engine. On its day competitive defenitly but what is its best times? High 4s from memory and that is slow these days.
Though watching Speedweek on the weekend and it was a pedal fest though a 4.40 was run with an engine detonating.
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Posted 23 February 2016 - 12:11
I'm old enough to remember hearing the Apollo 11 moon landing on a transistor radio in a pub garden and I did once catch a very poor glimpse of a Shuttle launch havng got up at a very silly hour to drive to see it.
To my simple mind those Apollo/Saturn missions remain the greatest engineering adventure ever. The way all that design and complexity becomes sheer power is awesome.
(O/T)
You should speak to Elon Musk, he can't even get a rocket to land on a flat barge, never mind a transistor radio in a pub garden!
(on topic)
In terms of spectacle, it didn't affect PS one jot, the racing was still blindingly good to watch *on tv.