The Bugatti Chiron uses a 16 cylinder engine and can go northwards of 250 mph. Would it be possible to go even faster with a gas turbine?
Top speed is limited by controllability, by power available, by gearing, and by tire survival. We don’t know which is the Chiron’s limiting factor.
In any case a gas turbine is simply a source of torque. The existing IC engine produces ~1500 HP. It’s not hard to find ICEs that make lots more HP than that. Admittedly not with the long term reliability which you’d get with a gas turbine.
Bottom line: Would more HP make it go faster? Maybe. Is a gas turbine the only, or even the best, way to get more HP? Not necessarily.
One question would be whether the car could safely go any faster if you increased the hp. According to Dan Neil’s review in the WSJ, Bugatti hasn’t run the car up to full speed yet, estimated around 285 mph IIRC. There are safety considerations even in controlled conditions with professional test drivers.
But on the simpler question of whether you could stuff a more powerful gas turbine into the car than the ~1500hp W16 piston engine, I think maybe. Back in the 1960’s, versions of a/c gas turbines stuffed into Indy cars were competitive enough, or even had the advantage, to where the rules were changed to ban them. The SXP-Paxton turbine Indy car used a 500hp version of the ubiquitous Pratt and Whitney Canada PT6 small a/c turbine. The highest power versions of that engine now have ratings up to around 2000hp, and weigh, engine only, in the 200-some kg range. The previous Bugatti Veyron’s 1200hp W16 weighs around 400kg. But that’s not including the differences in accessory weight, and volume, like much bigger air intake and exhaust required for a gt.
Also to the extent the Chiron is supposed to be ‘practical’ in any sense (though overall it obviously isn’t, even as is), you’d have the problems of very poor fuel economy of simple cycle gas turbines at part throttle, and very hot exhaust. But just to go faster, maybe stuffing a gt in there could do it, again assuming the car could safely use any more than 1500hp for max speed.
Probably. There are gas-turbine-powered drag trucks that can hit 376 MPH. To be fair, Shock Wave uses three engines, to do that, but it should also be noted that it’s a pretty unaerodynamic vehicle. If you used one of those engines in a Chiron-shaped shell, I’d guess you could exceed 250 MPH.
Turbine-powered cars have broken the sound barrier, too. Like the Shock Wave though, Thrust SSC doesn’t use a turboshaft engine to power the wheels; it’s just using jet thrust.
In the 1967 Indianapolis 500, a turboshaft-powered car almost crushed the entire field of competitors; it took the lead early in the race and kept it until very close to the end, when its transmission crapped out. The same car crashed during qualifying the next year, after which race officials changed the rules to make turbine engine uncompetitive.
Ninja’d by Corry El…
You’d get the top end but you’ll definitely lose the acceleration. It would also be highly dependent on how you’re harnessing that power; are you hooking the turbine up to a gearbox a la any turbo helicopter or turbo prop or letting the exhaust push you directly like a jet dragster?
Turbines also tend to be comparative gas hogs (Not that Bugattis aren’t) so any savings in weight or space are going to be eaten by the larger fuel tank. Chrysler’s Turbine car was a workable concept and there have been attempts to run a few turbine race cars like the Lotus 56 and Howmet TX. I know there are a few modern examples floating around as well.
Part of the issue, of course, is maneuverability or control. Except on a prepared course or salt flat, what’s the point? As Paul Walker demonistrated, or this guy ( Fast cars and fast living at heart of Malibu mystery ) the current roads can barely handle “normal” fast cars.
The excuse my cars gave (according to BMW and Audi literature) for refusing to go over 210km/h was that you need to buy tires rated for higher speeds.
The other issue is gearing. Teslas, for example, excel at 0-60 because electric motors are far more powerful at low RPM than equivalent piston engines - and thanks to valve float and other mechanical issues, piston engines also have an upper limit. I don’t know but I assume that turbines have the same upper limit. So part of the designed upper speed is probably the gearing ratio, rather than an engine limitation? You then want to replace the gearbox. At what point is it a completely different car?
From what I recall, turbines aren’t the best for varying loads, they need to be up or around their operating limit. So, I think the added complexity and weight of a transmission to make the car “daily-driveable” would cancel out the advantages of the turbine. Race cars aren’t much different as they are also designed around very specific parameters and will swap transmissions depending on the track. Maybe some beast CV transmission that could take the HP would be in order?
Secondly: fuel. I’ve never heard of a turbine that could use pump-gas but have heard of them using diesel. No idea how consistent pump-diesel is.
Lastly: exhaust temp. To be road legal it’ll have to have some sort of emissions control. Even diesel engines need catalytic converters now. No idea if the higher exhaust temp of a turbine will burn off the particulates of diesel which would be a good thing or a bad thing. But, yeah, a cursory Google search on turbine exhaust temp is that it’s way way higher.
Hard to answer not knowing much about the car itself.
You could drop in an 850CID V8 alky fueled blown hemi and get a lot more power
with out even going the turbine route
Question is can the car handle it?
Because the car handles at 250 does not mean at 300 it does not just lift right off the ground.
And i think even the greatest tire in the world reaches a limitation where it is just no longer possible to control the vehicle sitting on it.
Also can the vehicle itself even take the increased power? or will the frame/chassis begin to warp and deform?
Lots of things to consider besides simply engine power.
The existing engine may well go faster with a different configuration if it gives up things like drivability etc.
OP needs to clarify what type of gas turbine. Turboshaft? Turbojet?
anyway, in the space occupied by its current W16 engine, you could likely fit a 4,200 hp Honeywell T55 turboshaft, which would indeed get you higher top speed. but acceleration would be slow at least off the line. Plus you’ll need to make sure you have the exhaust duct clear to deal with the gas flow.
turbines are only really “efficient” running at peak rated load. below that they’re horrifically thirsty. the problem with a gas turbine is that its pressure ratio (analogous to a piston engine’s compression ratio) varies with engine speed; as the compressor slows down the pressure ratio drops and so does the engine’s efficiency.
just use kerosene; civilian jet fuel is basically 1-K with aviation-specific additives.
diesel fuel itself doesn’t cause particulates, it’s because diesels are stratified-charge compression ignition engines. The “stratified charge” part means the droplets of the burning fuel are not completely mixed with the air which forms soot particles. Gas turbines are continuous-burn engines, but still don’t completely mix the fuel with air. hence why jet airplanes still emit some degree of black smoke on take-off.
but the real elephant in the room is simple physics. The drag force on the car goes up with the square of the speed, so if you want to go 2 times as fast the drag force is 4 times higher. and the required power goes up with the cube of the speed, so to go twice as fast you need 8 times the power.
Agree overall.
But that last sentence says that to get to a mere 500 mph (:eek:) we’d only need 1500*8=12,000 hp. Here’s your “drop-in” replacement engine: Europrop TP400 - Wikipedia. That’s probably enough for our OP’s tastes.
“More power!” as xkcd might say.
nah, just use a Top Fuel dragster engine; you’d just better get up to 500 mph within about 6 seconds or so 'cos the engine won’t hold together for much longer than that.
That’s the big difference isn’t it? The TP400, supplied with fuel and oil, can pump out 11,000ish shp for probably 2 continuous *years *before anything broke. At 500 silly mph that’s 8.8 million miles.
The top fueler would never live 2 continuous minutes at high power output. Sometimes they don’t even make it two continuous seconds. Top Fuel Dragster: catastrophic engine failure - YouTube
One of the strengths of gas turbines is easy adaptability to a wide range of fuels. You can definitely burn gasoline in a gas turbine. In the early days of jets on aircraft carriers ca. Korean War the ships still had only avgas tanks/systems for their mixed jet and piston air groups so the jets burned avgas (though it that case some lube oil was blended into the jets’ gasoline since their fuel pumps hadn’t been designed to accommodate gasoline). OTOH the J-47 booster turbojets on B-36’s were adapted to burn avgas, no separate fuel system just for them. And nowadays the AGT1500 gas turbine on the M1 tank is said to have a fuel system capable of burning gasoline, though I guess that’s seldom if ever actually done in practice.
Or diesel fuel. So fuel wouldn’t be the issue but the ones I and now others mentioned like especially poor part throttle specific fuel consumption of simple cycle gt’s and their very hot exhaust*. And also as mentioned while it’s somewhat apples and oranges to design a car around a piston or gt engine, since other stuff would change, it’s absolutely apples and oranges to compare heavy duty power plants to ones expected to (maybe) last for hours, or minutes. Even comparing a PT6 to a car engine, the PT6 gets no credit for its far higher reliability and operating life, or alternatively there just isn’t as much use for that advantage even in a regular car. And I’ve read the average Bugatti Veyron gets driven 800 miles a year.
*the engine on the M1 partly addresses these by having a recuperator, OTOH it actually has lower power to weight ratio than competing high performance tank diesels: its advantages are in simplicity, low noise etc not higher power to weight ratio.