m477 said...

QUOTE]How come every car like the Supras, Skyline GT-Rs, RX-7s that are modded to make make 1000+ hp are all turbo and not supercharged? I'd like to see someone try to make 1200hp in a 2.6 liter 6-cyl with a supercharger![/QUOTE]

Umm... come back to reality, my friend. I'm not going to bash Turbos... they are a good, economical way to get horsepower. However, superchargers are just as viable. There are several cars out there that come stock with superchargers and are just as, if not more impressive than turbo equipped cars.... Cobra and Benz mentioned on this thread are just two examples.

If you want to pull out the modified car measuring stick... well, I have yet to see a turbo top fuel eliminator dragster. They all use superchargers and turn about 3x the horsepower you quoted above.

The bottom line is, for street use, they are two different means to get power. Turbo is cheaper, but higher maintenance. Supercharger is more expensive, but offers a more even increase in the powerband.

Personally, if I had to have one, I'd take the supercharger because it offers more use in daily driving... I can use it off the line or in passing situations. The turbo is more effective when you already have revs. Just my .02

 

Because I'm insanely curious, thought I would share this with the group to follow up my last message. Data taken from http://bmeltd.com/dragster.htm, but I bet you could find similar figures by searching the web a little more extensively...

Stats for the BME Top Fuel Dragster...

Displacement .... 500 cubic inches/supercharged (that's 8.14 liters for those who only speak metric...)

Horsepower.... 6000hp at 8200rpm!

1 - comparisons:
Turbo... 1200hp for 2.6L, or 461.5HP/L
Supercharger... 6000hp for 8.14L, or 737.1HP/L

2 - please note the peak HP rpm... what was that about superchargers not making power at high rpm?

Granted, point 1 is kind of silly since no one is going to use a top fuelie as a daily driver, but the second is not unique to racing superchargers. They make power through the entire rpm range if built properly

 

"Spooling up" means lag. Superchargers give instant power. I, for one, enjoy the sound of a gigantic roots blower on top of a masssaged V8. There's nothing like that sound.

 

If I remeber reading correctly their is a large turbo manufacturer who is developing a turbo that spools up faster with the assist of an electric motor. The advantage of this application is that your turbo has a supercharger feel as the electic motor produces the forced air till the exhaust pressure builds up and takes over. The advantage is that it allows you to get supercharger performance at low end with out the excess friction (ie better fuel millage).

 

Something that many of you fail to realize about the supercharger is that it has more parasitic loss than the turbo. At the same boost levels the turbo will make more power. Now using a roots type supercharger you will make that boost right off idle, but a properly sized turbo should start spooling by 2-3k rpm, and be fully spooled shortly after that.

Since at the same hp levels the supercharger is running more boost it will be putting more wear on the engine than the heat from the turbo will. Also consider the ease in intercooling a turbocharged engine, it is 1/10 the work of intercooling a roots type supercharger. So after considering the heating of the air caused by compressing it in the supercharger to the intercooled air from the turbo, the difference will be negligible if not in favor of the turbo.

Another misconception is that the n/a engine will be more responsive. Actually, the same engine, turbocharged, will be just as responsive, it will have approx the same output of the n/a engine up until it spools, and from there on out it will have more. It may seem less responsive due to the power curve being less linear, but it is actually very near to the same.

As for maintenance a turbo may be more complicated, but there is nothing to worry about other than the oil, and a minute or so of calm driving after prolonged full boost driving. The supercharger will require its belt to be replaced regularly.

Something else that many of you complain about is the lag when compared to the supercharger. A roots type blower has no lag, but the centrifugal blower will have similar lag to a turbo. Now you say you don't want the lag for your stop light drag races and such. How often due you launch at less than 3-4k rpms in a race? At that engine speed the turbo will spool almost instantly upon launching the car.

So in the end a turbo, while more complicated in implementation will be more efficient, more powerful, and less detrimental to the life of your engine, assuming similar boost levels.


ek

 

Yes, but they can only do that with a tank full of nitromethane and with rebuilding the engine after every single race. Excellent comparison.

The cars I was talking about are STREET cars running high octane gasoline and producing 1200+ hp and not needing to rebuild the entire engine after each run down the drag strip. Again, you just can't do that with a supercharger.

 

Can I get 2, that should give me about 100 HP....


That's Hillarious, if I saw that on someones car, I would blow it up....

 

Garrett has had the E-Turbo (as they call it) out for a few years. I saw it intoduced at the Frankfurt Auto show over a year ago, it looks just like a normal turbo. I have not seen it used yet though....

 

Personally, I think a non-intercooled, low-boost SC (much like the Comptech SC for the NSX) is the best option overall for the 350. An intercooled, twin-turbo setup on the 350 may be a maintenance nightmare.

If you don't believe me, then try owning/maintaining a 300ZX Twin Turbo for a while. Not easy to replace turbos. Not easy to locate boost leaks. Not easy to diagnose. (The Supra Twin Turbo, on the other hand, is a different story -- it has a simpler turbo setup)

Michael.

 

Oh, now you say so. At first, I could have sworn you said:

How come every car like the Supras, Skyline GT-Rs, RX-7s that are modded to make make 1000+ hp are all turbo and not supercharged? I'd like to see someone try to make 1200hp in a 2.6 liter 6-cyl with a supercharger!

So what's your point about 3000hp drag cars needing rebuilds after every race? Aren't turbocharged F1 cars rebuilt after every race as well?

If anything, the rebuild indicates that the block can't handle that amount of power and stress. It should have nothing to do w/ whether a SC can produce the power or not (which I thought was the original point). Besides, would you want to go a full race season w/o rebuilding a motor if there was $$$ at stake?

And don't believe the hype about those 1000hp Supras. Supra owners tend not to publicize that they've blown a motor. Some high hp Supras are on their 2nd, 3rd, and maybe even 4th shortblock.

Michael.

 

You can use an intercooler with the supercharger if you set it up this way:

http://www.jacksonracing.com/pages/p...ichose_prt.gif

I think you would be able to use a small roots blower in the 350Z like you can the centrifugal type along with an intercooler. It would be placed where the stock intake box is and run off the pulleys there also like in the pic.

 

Actually, before the turbo spools up, you will most likely have LESS power than you would in a NA engine since, in uprgrading to a turbo, your compression ratio. will most likely have to be lowered.

So the lag then becomes even MORE apparent ina turbo.... I don't care if a supercharger is thermodynamically less efficient that a turbocharger, it sure as hell is easier to maintain. Less parts... And, as mentioned a million times,, NO LAG. So if it can get me close to 400HP with no lag,, I'm all for it.

RaymanZ

 

This debate is kind of like the "which color looks best on the Z" debate. There will always be fans of both turbos and SCs. People like each for different reasons.

If Nismo offers either (especially if it does not void the warranty), i will buy and have either installed. My preference would be for a supercharger , but that does not mean I would look down my nose at a turbo if only that was offered. To me, the bigger question will be how much gain to get for my buck and still have maintenance coverage.

As for...
I'm sure the cars you are referring to are not "Street cars" either. The parts they have used to get the proposed 1200+HP (probably overstated... show me dyno slips), I bet state quite clearly "for offroad use only". At that point, by definition, the car is no longer a "street car". Don't believe, go ask your local inspection station or DMV.

 

When I said the same engine, I meant the same engine... High compression and boost go together fine so long as they are tuned right, in fact, aside from a racetrack where you can keep the boost up, it is better. Ask any turbo Honda guy...

But as it was said earlier, either would be a lot more fun than stock...

 

Isnt a turbocharger a form of supercharging?

With that said I think that a crank driven blower is better suited for the 350's engine powerband. But you can't beat having a boost controller to dial up power when you need it, it beats pulling over to change a pulley.

 

Actually, if the air is too hot this could cause detonation. Which can blow an engine. Hot air is also less dense, so compression will go down and the turbo will have to work harder to maintain the desired compression. That is why an intercooler is used on turbo cars. I think this is more dangerous to your engine overall than wear from a supercharger at full boost. In both cases, your engine is going to wear out faster than it normally will.

 

350Z33...

No, both are forms of forced induction. The end result for both is the same... higher air/fuel mixture flow. How they get there is different. Spin off exhaust gases or spin off of crank rotation. Because they generate the boost differently, they have different power gain characteristics.

 

Are you kidding me? Since we are looking at the possibility of adding TT, everyone should look at the installation and maintenance required. I own a a 93 RX-7 TT. If you need convincing, take a look at the "rats nest" under the manifold. I have all of my hoses swapped to Silicone with tie wraps. If ONE hose comes loose, you are potentially looking at hours to find the culprit.

Yes you can get high HP out of a TT setup. Is it worth it? There is an RX-7 (Rotory Performance) that ran an 8.92 on a 1.3 litre single turbo set-up. I don't believe this applies to anyone here. That car is not streetable.

Bottom line, a Super Charger makes the most since for me. Less maintenance, more reliable, and smooth powerband.

IMO, of course.

Eric

 

aftercooler...

 

Actually, compressions should not have to be lowered unless you plan on doing some extreme boosting. There are turboed RSX-S's running around with 9-10 psi and they have a higher CR than the 350. If you do 9 psi w/ a turbo in the Z we're looking in the 400 hp range.

Also, there are plenty of people that have reliability problems with SC's. The bottom line is: if you're not up to taking more care of your car, then FI of any form is definately not meant for you.