[ghporter]

Fyre4ce, I was referring exclusively to centrifugal and other turbine-based airpumps. The more advanced machines are beyond my experience, but obviously anything that produces compressed air without using turbine blades has a distinct high-speed advantage.

Did you know that superchargers were originally classified Top Secret by the Army? The application of superchargers to aircraft (piston) engines, and in particular to specific aircraft engines, was deemed to be important to keep from the enemy because superchargers let the aircraft fly much higher than planes with normally aspirated engines, as well as providing the craft with a significant horsepower boost. And these superchargers were all turbine-based.

[CMYKid]

Originally Posted by SuvsareRetarded

Exactly my point. Saying that turbocharger suck because you've driven a 1980s turbo diesel mercedes is a pretty stupid statement.

Read--->Think--->Comprehend------->Reply.

Try it sometime, tho novel for you, you'll get used to it.

Saying that turbos in 80's Mercedes sucked doesnt remotely resemble saying they all do. Neither did he.

[CMYKid]

Originally Posted by TurboMac

Don't be a prick Rob...

oh, you must be new here.

[TurboMac]

I know he can be, I was just aking that he not be at that moment. I'm new at posting, but I have been a lurker for quite some time. I see you are a fellow Ohioan, Cheers!!!

[TurboMac]

+2................

[TurboMac]

+3......

[TurboMac]

+4 Burps - Nice!

[d4nth3m4n]

dude, what the crap?

don't kill my thread.

[CMYKid]

Originally Posted by TurboMac

I know he can be, I was just aking that he not be at that moment. I'm new at posting, but I have been a lurker for quite some time. I see you are a fellow Ohioan, Cheers!!!

yeah, it was mostly rhetorical. most anyone would figure that out with the first post anyway. ;-)


is cleveland still part of o-hi-o? I thought the'd seceded.

But yeah, a bit south of ya.

[SuvsareRetarded]

Originally Posted by E's Lil Theorem

Check this beauty out:

What's funny is hte bodykit he has on that thing is for a coupe.... notice how the sideskirts cover up the bottom of his rear doors, making them totally useless. What a dumbass.

[Fyre4ce]

Originally Posted by Fyre4ce

I will have a reply for you, but not tonight. If I start doing thermodynamics calculations I'll be up until 1 AM. More to come...

I promised you numbers, so numbers you shall have!

Consider a base engine, 4.0L V8, 10:1 compression ratio, turning 6500 RPM, with a volumetric efficiency of 90%, an A/F ratio of 15:1, a BMEP of 10 bar, and an EGT of 1160 F.

Power = 291 hp
BSFC = 0.435 lb/hp-hr

Now, lower the compression ratio to 8:1, and add a turbo and an intercooler. Boost pressure is 17 psi, compressor efficiency is 65%, turbine efficiency is 55%, shaft efficiency is 95%, intercooler efficiency is 80%, and intercooler pressure drop is 1 psi.

Gross power = 565 hp
Loss from backpressure = 9 hp
Loss from compression ratio = 37 hp
Power = 519 hp
BSFC = 0.473 lb/hp-hr


Instead of the turbo, add a supercharger and an intercooler (same 8:1 compression ratio). Boost pressure is 17 psi, compressor efficiency is 55%, mechanical efficiency is 95%, intercooler efficiency is 80%, and intercooler pressure drop is 1 psi.

Gross power = 558 hp
Gain from boost = 32 hp
Loss from driving supercharger = 84 hp
Loss from compression ratio = 35 hp
Power = 471 hp
BSFC = 0.515 lb/hp-hr

Analysis:

Obviously, both the turbocharged and supercharged engines have significantly more power than without. Using these numbers, the turbo hurt BSFC slightly. Most of the effect comes from the lowered compression ratio, which is hard to combat. The loss from backpressure can turn into a gain with small improvements to the turbo's compressor and turbine efficiency but it's still likely that the turbo engine's BSFC will still be larger than for the naturally aspirated one.

The supercharged engine hurt BSFC quite a bit (~15%) and did not add as much power as the turbo, but this analysis obviously ignores the transient effects, of which the supercharger is king.

I can probably send my little spreadsheet to anyone who wants to play around with the numbers.

[SuvsareRetarded]

When was the last time you saw an intercooled supercharger? Seems to me that doesn't happen very often.... every factory supercharged engine I've ever seen has lacked an intercooler completley.

[Fyre4ce]

Originally Posted by SuvsareRetarded

When was the last time you saw an intercooled supercharger? Seems to me that doesn't happen very often.... every factory supercharged engine I've ever seen has lacked an intercooler completley.

I was thinking a water-air intercooler sitting between the supercharger and the intake manifold, which I have seen on factory supercharged engines. The SVT Cobra was definitely intercooled, but I can't think of any others right now - there is not a large pool of factory supercharged engines to look at. For someone throwing a supercharger on their street car, they are not very common.

I was also trying to do a fairer comparison between the turbo and the supercharger. NOT having an intercooler is a big disadvantage.

But no matter, here are the results for a blower with no intercooler, and I lowered the compression ratio slightly to 7.5:1 to account for the increased charge temperature:

Gross power = 434 hp
Gain from boost = 32 hp
Loss from driving supercharger = 65 hp
Loss from compression ratio = 34 hp
Power = 367 hp
BSFC = 0.513 lb/hp-hr

BSFC stays about the same, but power drops by a big margin.

[iT4c0]

I have to contribute this one here
I saw this on the free way. Pretty rice to me

[Kevin]

[SuvsareRetarded]

.... is that seriously a real neon limo?

[Kevin]

Yes

[Fyre4ce]

Originally Posted by ghporter

Did you know that superchargers were originally classified Top Secret by the Army? The application of superchargers to aircraft (piston) engines, and in particular to specific aircraft engines, was deemed to be important to keep from the enemy because superchargers let the aircraft fly much higher than planes with normally aspirated engines, as well as providing the craft with a significant horsepower boost. And these superchargers were all turbine-based.

I didn't know that superchargers were Top Secret but I did know that WWII was a period of rapid development in engine technology. A lot of the research done during that era is still useful today.

But, I think you're wrong about the centrifugal superchargers. The P-51's Merlin V12 engine had two roots blowers in series (two-stage) and was the most successful airplane engine in the war. Personally, I think a centrifugal supercharger would have been better than the roots blowers, with twin turbochargers being better than either of them, but it's hard to argue with the engine's success!!

The main design factors for airplane engines are the low air density (hence the big benefit from forced induction), the need for high power and low weight, and the relatively constant load and RPM (ie. "turbo lag" is not nearly as much a problem). Unfortunately for us car guys, gas turbines (which are superior in all these categories) soon took over at the cutting edge so we can no longer leech cool engine technologies from the aerospace industry.

[hamsher]

http://www.reubengathright.com/jpg/r...riousComic.htm

[ghporter]

Most of what I'd been working from was applied to the P-38 and (amazingly enough) the B-17. The P-38 had another advantage over then non-charged Luftwaffe fighters: twin, counterrotating engines. The P-38 could roll off in either direction with ease, while the Luftwaffe planes could roll off faster to the right (with engine rotation) than to the left. The P-38 pilot with a Messerschmidt on his tail could just roll left (fast!) and manuver onto the German's 6 o'clock with ease. It made the P-38 a not-well-liked plane among German pilots.

Supercharging the B-17 increased its range and ceiling by quite a bit, which is why the chargers were classified; they didn't want the Germans to supercharge a Junkers bomber.

Another important point about the Merlin is that Rolls managed to create a carburation system that worked in any attitude; up until that point, ALL piston engine airplanes had problems rolling all the way over, because their carbs would stall out. By making a carburator that wasn't dependent on being "upright," Rolls made the Merlin a much more wicked engine than it already was.

[teknopimp]

Originally Posted by iT4c0

I have to contribute this one here
I saw this on the free way. Pretty rice to me

another jetta:

[SuvsareRetarded]

Originally Posted by ghporter

Most of what I'd been working from was applied to the P-38 and (amazingly enough) the B-17. The P-38 had another advantage over then non-charged Luftwaffe fighters: twin, counterrotating engines. The P-38 could roll off in either direction with ease, while the Luftwaffe planes could roll off faster to the right (with engine rotation) than to the left. The P-38 pilot with a Messerschmidt on his tail could just roll left (fast!) and manuver onto the German's 6 o'clock with ease. It made the P-38 a not-well-liked plane among German pilots.

Supercharging the B-17 increased its range and ceiling by quite a bit, which is why the chargers were classified; they didn't want the Germans to supercharge a Junkers bomber.

Another important point about the Merlin is that Rolls managed to create a carburation system that worked in any attitude; up until that point, ALL piston engine airplanes had problems rolling all the way over, because their carbs would stall out. By making a carburator that wasn't dependent on being "upright," Rolls made the Merlin a much more wicked engine than it already was.

If I remember correctly, the engines on the p38 (my favorite airplane of all time) had 'turbosuperchargers' whatever the hell that meant. It also was the plane america's top WW2 ace flew. Richard Bong.

[ghporter]

Bong was quite a guy. He survived a whole lot of hell in the Pacific theater, got paraded around as a super ace, and then started test pilot duty-and wound up crashing and dying in an uprated version of the P-38.

Funny name? Sure, today. But he was quite a guy.

[SuvsareRetarded]

I've touched his plane.

[SuvsareRetarded]

I've touched his plane.

[Fyre4ce]

Originally Posted by SuvsareRetarded

If I remember correctly, the engines on the p38 (my favorite airplane of all time) had 'turbosuperchargers' whatever the hell that meant. It also was the plane america's top WW2 ace flew. Richard Bong.

I think when they say a "turbosupercharger" they really mean what you and I would call a "turbocharger." Turbochargers are, after all, technically a sub-class of superchargers so I think it took time before the original name was condensed.