It uses a Rootes blower at low RPM to develop 295 pound-feet of torque at 2200 rpm. At higher speeds the blower is disengaged as the turbo takes over to produce 316 hp at 5700 rpm. All from a poxy 2.0 litre inline 4!
That’s actually kinda nifty, because the big problem with either type of boost is that you’ve gotta run low compression ratios to make optimal use of it. But with low compression, the engine is a dog when the boost isn’t on. This way, it’s always on!
Volvo, of course, is installing these engines in – Volvos. Big heavy ones at that. Somebody’s gotta figure out how to shoehorn one into a Lotus Seven or something like that. Or, perhaps a Series 1 E-type – just to give this thread some Jaguar content.
Hi Kirby
This is like the Group B Lancia Delta S4… When the Engineers were told to “make horsepower” and don’t worry about rules. The 1800 cc engine made 500 hp and was capable of more I think…but for weight distribution they put the fuel tanks under the drivers seat and this didn’t end well…but the technology was developed during the great Group B times…30 odd years ago!!!
Matt
Another recent approach is variable compression ratio–high until boost is called for, then lowered. This approach seems to favor turbos, eliminating the need for low RPM boost or for boost without lag.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
5
This is like the Group B Lancia Delta S4…
Various articles mention this has been done before. Apparently VW did it a
few years ago on some cars that never made it to the North American
market.
I can certainly see how the issue would be integration. Having the blower
suddenly cutting in and out could be disconcerting. Apparently Volvo has
been working very hard on that, as well as packaging – with all that plumbing
and valving, you could end up with a rat’s nest for sure.
BTW, apparently newer renditions of the Volvo T6 are up to around 350 hp.
It supposedly sets some record for production street cars.
– Kirbert
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
6
Too many moving parts…
That’s the way I feel about lots of modern technology. Engines don’t bother
me that much, if one croaks you just pull to the side of the road. Braking and
steering systems are riskier places to be piling on the complexity, IMHO.
When I worked at P&WA, fighter aircraft were just starting to incorporate
“fly-by-wire”, where the pilot only controlled inputs and electronics actually
moved the control surfaces. There was a LOT of resistance to that idea. In
the end, though, fewer aircraft were probably lost to control system failures
than had previously been lost to pilot errors that the new control systems
prevented. There were certainly some teething issues, though.
I worked on the engines that went in the F-15 Eagle. The rudder control on
that aircraft involved a cable of sorts. The housing was racetrack-shaped in
cross section, and the moving core was a flat ribbon with grooves down both
sides that moved back and forth in the housing with balls running down
either side of that racetrack-shaped housing. A ball bearing cable, if you will,
connecting the pedals in the cockpit directly to the rudder at the rear end of
the plane. I think that’s the last time they did things like that, though,
because the F-16 Falcon was fly-by-wire.
Nitrous is more reliable.
Then how come so many people who go to nitrous seem to end up
grenading their engines?
That’s because the engines have too many moving parts. Nitrous is a simple way to prove that.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
8
Another recent approach is variable compression ratio…
Does anyone know how this is done? I could see going beyond merely
boost vs. non-boost to having much higher compression on low-throttle
cruise for fuel mileage, dumping much of the compression as soon as you
need more throttle.
What is it, the Miller cycle in which the intake valve is kept open through part
of the compression stroke in order to effectively reduce compression and
throttle? The problem with that is: It’s when you’re reducing throttle that
you’d like to be INCREASING compression!
They’re claiming remarkable achievements in fuel efficiency from the Volvo
T6. That’s interesting, since I think, on paper anyway, boost should be a
detriment to efficiency. With NA you’re already wasting energy by only
utilizing part of the expansion of the burning charge, letting the rest get
wasted out the exhaust. As soon as you boost, you’ve got that much MORE
charge to get wasted. And with the supercharger, you’re wasting yet more
energy providing the boost! The benefit of getting the needed power from a
far smaller engine with fewer cylinders must outweigh these factors.
– Kirbert
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
9
That’s because the engines have too many moving parts. Nitrous is a
simple way to prove that.
Back in the day, if you ran your engine too hard, you’d “throw a rod” and
possibly punch a conrod through the side of the block. Conrods were clearly
the weak link in an engine. But nowadays, spending a few enjoyable hours
going through the YouTube videos of engine failures gives an entirely new
appreciation of the stresses on virtually every part of an engine. Dragsters
with big blowers often seem to be blowing the entire top off the engine.
Others throw the entire crankshaft out the bottom, ripping all the main
journals out of the block by force. And one of the most amazing videos I’ve
seen, which was a tractor pull, the guy threw a BLOCK – the crankshaft,
conrods, and pistons stayed in place in the tractor while the block itself was
thrown completely out the top of the tractor and fell on the ground beside it.
Indeed… back in the day you were mostly talking about an engine which was more or less standard parts, carefully modfied, matched, and assembled. “Pushing the envelope” generally meant a premature failure typical for that engine in production form, with similar, if more catastrophic, secondary damage.
With the range of materials and techniques available today, “pushing the envelope” seems to be much more advanced… If you call loading things up such that the block returns itself to the nodule Iron phase “advanced”.
Kirbert, I am pretty sure Saab patented a variable compression ratio engine that moved the main bearing plane somehow. Didn’t they get bought by GM, then got sold to China??
Right; GM shelved Saab’s engine. I was thinking about this one from Nissan, which was patented ~15 yrs ago but just coming into production in the 2018 Infiniti. It’s direct injection, VVT, turbo, etc. Adding the variable CR gets it pretty close to all you can do before biting the bullet and going electric.
Atkinson cycle originally–a Brit no less, improved by Miller (US). Because intake valve timing is now variable on the fly, delayed intake valve closing can be switched in and out as needed. Evidently, the variable compression Infiniti engine does this.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
14
Didn’t they get
bought by GM, then got sold to China??
It’s Volvo that got sold to China. The sale of Saab to China got blocked,
resulting in lawsuits back and forth.
Tilting the top half of the block. Yeah, that’d do it I guess, but that’s certainly
a lot of complexity, especially when you consider cam drives, etc.
I’ve long wondered if you could accomplish variable compression ratio with a
plug that screws in and out of the combustion chamber as required. I dunno
how to do it so that it wouldn’t get crudded up with carbon deposits, though.
I seem to recall seeing some arrangement where a rocking lever connected
the conrods to the crankshaft, and moving the other end of this lever
changed the compression ratio.
Has anyone managed to bring a variable compression ratio engine to
production?
Not that bad actually. I have an e55amg with a supercharger. It appears to windmill in the airflow on a clutch drive at some percent slip below the airflow thru the engine…then when you ask for it there is a slight twitch and you’re on afterburner.
It must just lock from whatever slip,it runs to synchronous speed which is not a big deal on the drive system and is hardly noticeable. The drive belt is only a small multi ribbed flat belt.
I suspect when you are on turbo boost the clutch just disengages…
Matt
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
17
Well SAAB actually got sold to China but not the name…
I was just going by what was on Wikipedia. It says the deal with China fell
through because GM objected to the technology going to China. So Saab
got sold to some Swedish electric car company, which then restarted the
production line! Then THEY got sued for using the Saab name. After all that
got sorted out, supposedly they plan to restart the production line again –
producing exactly the same car, but no longer with the name Saab on it.
The cars that was made at the time when it whent busted is today slightly modofied made in China under some name…
to my knowledge… but hey Ive been wrong before LOL…perhaps it was the previous generation that got sold to China…
it was on the news just some days ago that the case will be in court soon… after almost 3 years of preparation from the prosecutor side…very complex story involving some very dodgy peolpe .
However there will never be any SAABs made again thats for sure…
I’m personally quite hooked on the latest (not in the US yet) Audi TT-RS with the decedent of the famous 5 cylinder world rally champion engine, now in all aluminum producing a whopping 400 HP and 480Nm. Faster than the R8. Now, where did I put my wallet ?