N4HHE

Based on my reading it is more than MPG. DI gives better control over the combustion process for emissions too. The better the emissions are controlled the more HP the engine can produce. Just consider how Porsche only got 234 HP from a 4.7L V8 in 1983 due to emissions. Today a Subaru Outback gets 182 HP from a DI normally aspirated 2.5L 4 cylinder.

pawprint

If we take into consideration that little thing called a turbo charger, as found on the 2.5L Subaru, we find when twin turbos were part of the Porche 4,7 package, it produced somewhere in the 540 HP range. I think it is always better to compare apples to apples NA to NA, FI to FI, otherwise you confuse yourself.

Napalm

so just to be clear here - it's about much more than just fuel economy. It's about the power rating too. ESPECIALLY in a force induction mill - a little less so in a NA mill.

but keep in mind with DI you are able to run higher base compression ratio and put pressure on top of it -without predetonation like you would get with port injection only. Without the worries of the pressure and heat being too high a DI setup can handle extra with the fuel combusting on the intake valve. Like all things there are compromises and to be fair here. the MPI and DI setups really do get some of the best of both worlds and as complicated as it seems the setup is actually fairly simple.

Now complicated is when you get into the ideas of the spark ignition - compression ignition gasoline engines. I think mazda is trying to call it something else - but back when I was in school the theory was SI/CI gasoline engine. I think some people tried to call it a stratified charge but at any rate it's an engine that moves to compression ignition at higher RPM and power need - shutting off the sparkers. Crazy right.

N4HHE

Read it again. I’ll help: “Today a Subaru Outback gets 182 HP from a DI normally aspirated 2.5L 4 cylinder.”

Porsche never put turbos on 1983 4.7L V8.

pawprint

No they did not put twin turbos on the 1982; however, when they did put a turbo on it, 540+ hp. 1982-83 Porche, turbo produced 296HP, 911 turbo. Thus once again proving, If you want big power-FI and V8.

N4HHE

There was no V8 turbo until 2002. The V8 got DI in 2007. You pretend like you want to compare like-with-like but you keep citing the highest number you can find irrespective of the engine, year, country, or displacement. You are citing European emissions not USA. The Wikipedia article cites European trim but doe not annotate as such.

I cited 182 HP 2.5L water cooled boxer 4 DI normally aspirated 2021 Subaru Outback vs 234 HP 4.7L V8 water cooled port injected 1983 USA smogged 928S as evidence of the best an exotic manufacturer could could do in 1983 vs a commodity grocery-getter of today.

In 1983 the Porsche 928S was the fastest top speed production car on the market until the 1984 Corvette started shipping.

pawprint

Of course, in the 80s Porsche turbo charged a 2.8 liter putting out 444hp, now that weve suddenly inserted the smogged problem, I guess you can kill any good engine by making it "smog" friendly; however, if not "smogged" the engineering of that said engine can be rightfully compared. I can tell you, without a doubt, huge numbers of drivers (so many in Ca) are running "tunes", most are illegal in the state, in fact, the gov has ordered a crack down.
Regarding, 'As evidence of the best exotic manufacturer could do in 1983..." well, Porsch put out a flat six in 1983, 2.6 liter that delivered 630 HP... Porsche 956, that puts them 0.1 liter larger in displacement, but somewhere over 300% More HP. So I guess the "exotic manufacturer" could do pretty well, back in the old days. BTW, 630HP really isn't that bad even for today's grocery getters...

Napalm

LOL ok so a devlopmental prototype race car from the 80's which was a flat 6, with a turbo, and the first progressive injection system which became MPFI - and was the development mule for the first dual clutch gear box.

yeah and there is alot of speculation on how much HP and torque those made, vs how they were tested. Interesting car though.

pawprint

If we are talking about engineering, what was/is great today vs. 40 years ago, I do believe it is well worth mentioning. The subaru mill is a good little mill, but hardly an engineering feat. The subaru boxer is used so often in X aircraft, it is hard to argue that their availability and reliability are bad, but a chevy 350 is reliable and very available....

blksn8k

DI also allows the use of a higher compression ratio due to lower combustion temps. Higher comp ratios also allow for better efficiency. The '18 F-150 gen III 5.0L was the first year for dual injection on the Coyote V8. The previous gens used port injection only. The comp ratio of the gen III was also raised from 11:1 to 12:1 and runs just fine on 87 octane.