# turbocharging versus n/a engines: N/A takes it.



## pdz (Nov 17, 2002)

turbos are nice and everything, but there just isn't any replacement or substitute for more cylinders, displacement, or variable valve timing.

WRX is fun, but the engine is downright coarse and extremely peaky. drive it back to back with the e46 and the sheer thrust from a standstill of the straight bavarian six (and these aren't notable for torque characteristics) puts the issue to rest for me. displacement and VANOS win and win and win for me.

just took some firsthand experience all over again to change my mind.


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## Plaz (Dec 19, 2001)

pdz said:


> *turbos are nice and everything, but there just isn't any replacement or substitute for more cylinders, displacement, or variable valve timing.
> 
> WRX is fun, but the engine is downright coarse and extremely peaky. drive it back to back with the e46 and the sheer thrust from a standstill of the straight bavarian six (and these aren't notable for torque characteristics) puts the issue to rest for me. displacement and VANOS win and win and win for me.
> 
> just took some firsthand experience all over again to change my mind. *


Ahhh, but how 'bout a supercharger on an M54?


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## pdz (Nov 17, 2002)

*wouldnt' touch the current crop.*

all of the blowers i've seen are hack kits (no offense to HACK the man) and use centrifugal blowers.

so the problem is the same as with turbos, but these turbo kits are factory OEM engines whereas those are godawful things (i owned one on an S52 M coupe) that have hot start problems, fuel delivery issues, fouling spark plugs, gasket issues....idling issues.....it all is very unpleasant. not to mention the peaky power.

if there were a positive displacement blower a la eaton or the vendor for the IHI blower that MB uses, that might be a consideration, Plaz. but that is ungodly expensive because it would require a new intake manifold.

so, "no".


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## RKT BMR (Sep 7, 2002)

I just can't endorse anything you've said here about charging an M54 engine in an E46... I've done it.

I have an ESS blower on my 330cic. Installed it myself. "Hack kit" does not characterize this addition to my bimmer at all -- the parts and materials are first-rate, fit perfectly, and worked as advertised the first time I turned the key.

I have 8k miles on it now and it has been getting faster and faster. I was advised that this would be the case -- as the blower itself went through break-in, it presents less parasitic drag on the motor, and gets more efficient at compressing air.

I have had absolutely no problems. Motor runs as good, or even better, than it did before the install.

And, the bottom line: It's a power monster. I'm gonna dyno over the holiday break, but I'm pretty sure I'm getting near the 300 ft-lbs / 335bhp at the crank as advertised. The torque curve is generally about the same shape as the stock engine, just shifted up. No doubt thanks to the VANOS and other great BMW technologies.

You can take a look at it at Bimmerfest in April, if you'd like. Or check out my writeup about the install. Or, check out MarvelPhx excellent DIY writeup of his install in October.

Try to catch me during the Bimmerfest Road Rally


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## in_d_haus (Jan 2, 2002)

There's no replacement for displacement! :thumbup:


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## pdz (Nov 17, 2002)

*'thought i might see you.*

and how do you feel about the cost of that kit (i'm assuming you did brakes, suspension and clutch to keep up with the power) compared to an M3convertible?

naturally, my feelings about supercharging stem from one of the most reliable kits made, by Dinan, running 6psi and spitting out 340HP in conservative fashion on an S52 motor.

it was fast.....just not my cup of tea because you really had to get up there in the rpms to get max power, and it did suffer big time in hot weather.

you have an aftercooler?


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## pdz (Nov 17, 2002)

*heat soak at the track, too.....*

...forgot to mention heat soak on an engine not designed for that extraneous heat in the engine compartment.

at the track, it got some serious heat soak.


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## Kaz (Dec 21, 2001)

I agree, centrifugal superchargers just don't work well in a street car application. All the addon kits that use them (anything that uses a Vortech) seem to use em strictly for packaging reasons.

Every current factory supercharged car I can think of uses Roots or Lysholm (basically a modified Roots) blower. There are also variants like the Whipple Their adiabatic efficiency is lower than that of a centrifugal blower but they're much easier to add on.

The same adaptability also applies to turbos vs a centrifugal SC. Their operating principles are similar, though turbos are more tunable since you're not bound by engine RPM to drive the impeller and instead can use different housing and turbine combinations to do the tuning. (SCs typ. run at 2x crank speed whereas turbos can run 5-10x faster than that) But since you need to tap the exhaust, its not always easy to retrofit.

As for boosting a modern BMW engine, I have my reservations because they're not designed that way. The dynamics involved when the intake charge is pressurized has all sorts of ramifications that can't easily be solved just by bolting crap onto the outside.


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## RKT BMR (Sep 7, 2002)

*Re: 'thought i might see you.*



pdz said:


> *and how do you feel about the cost of that kit (i'm assuming you did brakes, suspension and clutch to keep up with the power) compared to an M3convertible?*


If my only objective was the preformance, I would have purchased an M3. My car's a hobby, and I like to tinker. The SC was an interesting and gratifying challenge.

So were the sways, exhaust, alarm, clears, shifter, etc. etc.

Brakes are on the list, as are upgraded springs/struts/shocks. Clutch? I'm not convinced. Depends very much on how you drive the car. I don't race or autox, so my main use of the power is in normal driving (passing, etc.). That's what I wanted it for.


> *it was fast.....just not my cup of tea because you really had to get up there in the rpms to get max power, and it did suffer big time in hot weather.
> 
> you have an aftercooler? *


I develop quite a bit of power from 2500 on up. It peaks, of course, around 5500-6000, around the same place as a stock M54 engine. I think you're possibly mistaking turbo lag problems with superchargers? Drove the car for a year before I boosted it, so I had a pretty good feel for the power curve of the stock motor. With the blower on it, it just added power across the range.

No after/inter cooler. As for the hot weather comment, that affects all engines, not just FI. Air is air is air... An engine can move a particular _volume_ of air, not a particular mass. If a 20deg temp increase outside drops air density 10%, then NA and FI engines will see the same proportional drop in power. NA engines can't magically cause oxygen molecules to appear in the cylinder that blown engines can't


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## nate (Dec 24, 2001)

I agree...

I think N/A is best. The only aftermaket S/C kit that I could have near full confidence in is the Dinan kit.


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## RKT BMR (Sep 7, 2002)

Kaz said:


> *As for boosting a modern BMW engine, I have my reservations because they're not designed that way. The dynamics involved when the intake charge is pressurized has all sorts of ramifications that can't easily be solved just by bolting crap onto the outside. *


The only comment I can make here, Kaz, is that I'm running a Vortec (centrifugal), have been for 8k miles, and it hasn't caused any problems. No check engine lights, no fault codes (I've checked), significant power boost.

My own direct experience doesn't bear out what your cautioning here. Did you mean, perhaps, bolting on an SC without modifying the ECU programming? If so, I'd wholeheartedly agree. That would be stupid.

Of course, that's not the case with currently available kits from ESS, RMS, and others. They all include new SW for the ECU (fuel maps, VANOS timing, ignition, etc. etc.)


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## pdz (Nov 17, 2002)

*after/intercooling is pretty important.*

RKT:

aha! i sensed it was as so. i, too, was tinkering when i should have just bought an S54engine'd M coupe.

but i think the intercooler issue bears some second thought because the vortech unit gets quite hot, even though the 330 engine has an oil cooler, that oil still runs pretty darn hot. i think the heat soak that sets in on an forced induction engine is far more detrimental than that of an N/A engine. i think a dyno bears this out, as well.

for streetable occasions it does not matter unless you are in 100degree heat index conditions, and you notice it pretty badly when the ignition gets retarded significantly. autoX, track and rallying, it will impact longevity, i should think.

my main point is: even engines designed for forced induction with cooled pistons and lower compression are still suboptimal, in my estimation, to displacement and more cylinders. moreover, since i have had the same experience as you (only about 18k miles after it was said and done), i cannot say that my mind has changed about after OEM kits. posi-blowers are king in the OEM arena for several reasons, but power characteristics are high among them.


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## JST (Dec 19, 2001)

pdz said:


> *turbos are nice and everything, but there just isn't any replacement or substitute for more cylinders, displacement, or variable valve timing.
> 
> WRX is fun, but the engine is downright coarse and extremely peaky. drive it back to back with the e46 and the sheer thrust from a standstill of the straight bavarian six (and these aren't notable for torque characteristics) puts the issue to rest for me. displacement and VANOS win and win and win for me.
> 
> just took some firsthand experience all over again to change my mind. *


The big "but" here is that the WRX is an extremely peaky engine, even among turbos. There are lots of turbo applications out there that have friendlier low and midrange torque curves. The 1.8T is one of them; in fact, if there's one complaint I have about the VW, it's that the power levels off too soon, and doesn't keep building frenetically all the way to redline.

The Volvo 2.4T (LPT) is the same way, offering lots of punch right off idle.

Either one of these engines feels a lot stronger than the M52/54 B 25 off idle, but neither is as linear. I've never driven a turbo engine that completely gets rid of lag, and in both the Volvo and the VW you can feel the briefest hesitation at low RPM while the compressor spools up.


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## HW (Dec 24, 2001)

pdz said:


> *displacement and VANOS win and win and win for me.
> *


having variable timing and LIFT would be nice too. if i'm correct, only honda and yamaha has variable lift valves. (yamaha/toyota engine in the toyota celica gts. ) but the variable lift technology is supposed to be more expensive though.


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## Kaz (Dec 21, 2001)

RKT BMR said:


> *The only comment I can make here, Kaz, is that I'm running a Vortec (centrifugal), have been for 8k miles, and it hasn't caused any problems. No check engine lights, no fault codes (I've checked), significant power boost.
> 
> My own direct experience doesn't bear out what your cautioning here. Did you mean, perhaps, bolting on an SC without modifying the ECU programming? If so, I'd wholeheartedly agree. That would be stupid.
> 
> Of course, that's not the case with currently available kits from ESS, RMS, and others. They all include new SW for the ECU (fuel maps, VANOS timing, ignition, etc. etc.) *


I've seen cars with turbo kits made out of radiator and dryer hoses that run "fine", so your first comment is meaningless to me. Yes, there is always the possibility that any level of hacked-together crap could run indefinitely. I'm 100% positive there are cars out there that have gone 100k mi without an oil change. That doesn't mean its a good idea.

As for modifications, I'm talking about physical ones. I know ESS's kits, at least, have reprogged ECUs and bigger injectors, which are steps in the right direction and frankly is about all you could do without opening the motor.

But there are lots of physical differences that should at least be accounted for when introducing boost. Its more than I have expertise in, and beyond the scope of going into here, but everything from compression ratio, to cam profiles/timing, head sealing, piston design, head quench, intake manifold design, etc. etc.

A good example of this would be to examine the history of a Japanese engine that started out as a NA design and slowly adapted over the years (the Toyota 3S-GE might be a good example; it started as a ~140HP NA motor but was modified over the years to get to about 500 reliably) to accomodate initial boosting, then later to accomodate more.


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## Kaz (Dec 21, 2001)

*Re: Re: turbocharging versus n/a engines: N/A takes it.*



HW said:


> *having variable timing and LIFT would be nice too. if i'm correct, only honda and yamaha has variable lift valves. (yamaha/toyota engine in the toyota celica gts. ) but the variable lift technology is supposed to be more expensive though. *


AFAIK there are 3 systems in existence that vary lift by messing with cam profiles in some way. Honda DOHC VTEC, Toyota VVTL-i and Nissan VVL. All the other systems vary timing but not lift, though I think Valvetronic might be able to accomodate it.


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## Plaz (Dec 19, 2001)

I don't pretend to be educated or knowledgeable enough to definitively state anything on the subject, but I have been intrigued, fascinated, and tempted by the idea of adding a supercharger to my 330i for awhile now. I still don't think I'd do it until I was out of warranty period, for obvious reasons.

From what I've read on the boards, however, there are many out there who think it's a bad idea. Then there are many who think it's an incredibly awesome idea.

Those who have done it seem to report universally good results, with the exceptions of the occasional burnt-out clutch or stupid overpowered driving mistake. This seems like a good sign to me, although there are still relatively few people who have done this with an M52/M54.

I'll be curious to see how opinions change/remain the same once some of these S/Cd E46s get over 100k miles on them. To me, the durability of the engine long term when subjected to the extra stress of the blower would be my main concern.

:dunno:


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## Kaz (Dec 21, 2001)

I've never asked him in detail, but in the years that he had it, a friend of mine started with a E36 318is and went through several remotorings, including at least 1 and possibly 2 rounds with supercharging. In the end, it all came out and a stock E36M3 motor went in, and that's the way the car exists today.

One of these days I'll have to get more details as to what made him take the blower motors out.


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## nate (Dec 24, 2001)

Plaz said:


> *I'll be curious to see how opinions change/remain the same once some of these S/Cd E46s get over 100k miles on them. To me, the durability of the engine long term when subjected to the extra stress of the blower would be my main concern.
> 
> :dunno: *


Not just the engine

http://www.e46fanatics.com/members/nate328Ci/subframe.jpg


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## Plaz (Dec 19, 2001)

nate328Ci said:


> *Not just the engine
> 
> http://www.e46fanatics.com/members/nate328Ci/subframe.jpg *


Right... that too, as we've discussed before.


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## Jspeed (Dec 23, 2001)

*Re: Re: Re: turbocharging versus n/a engines: N/A takes it.*



Kaz said:


> *AFAIK there are 3 systems in existence that vary lift by messing with cam profiles in some way. Honda DOHC VTEC, Toyota VVTL-i and Nissan VVL. All the other systems vary timing but not lift, though I think Valvetronic might be able to accomodate it. *


Add Porsche's VarioCam+ to that list.


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## RKT BMR (Sep 7, 2002)

Kaz said:


> *I've seen cars with turbo kits made out of radiator and dryer hoses that run "fine", so your first comment is meaningless to me.*


That's a shame. Of course, I hope it was obvious that I wasn't talking about hairdryers, radiator and dryer hoses, but if not, I was referring to well-engineered kits offered by reputable tuners, like ESS, RMS Dinan, etc.


> *As for modifications, I'm talking about physical ones. I know ESS's kits, at least, have reprogged ECUs and bigger injectors, which are steps in the right direction and frankly is about all you could do without opening the motor.*


Agreed. There's no argument that boosting places greater demands on the motor, and larger stresses on the parts, particularly pistons, rods, and cranks. The question is, can the motor as designed handle it? How much does the manner in which the car is driven impact stress and reliability? Can the cooling system keep up with the extra heat energy generated?

You know a lot more about these things than I do. But so do the engineers at ESS, Dinan, etc. From what I have been able to learn researching the question before I plunged, there isn't a simple answer to the question, "Is it a bad idea?"

The answer is, "it depends". Just like with a stock S54 engine, a boosted M54 engine can fail if pushed too hard. What's more, the margin for pushing it too hard is reduced by boosting it. The extra power tempts and encourages one to push it too hard. All of this can lead to failure -- no argument there.

But does this make it unwise to boost an M54 engine? FWIW, after looking into the question, getting to know a few people first-hand who had done M52 motors in 323's, etc., in my judgement it did not present a significant risk for adding power to normal street driving -- *my* application.


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## RKT BMR (Sep 7, 2002)

nate328Ci said:


> *Not just the engine
> 
> http://www.e46fanatics.com/members/nate328Ci/subframe.jpg *


Nate. if you wouldn't mind, could you interpret that pic for me? I'm not familiar enough with what should be there to tell what's failed. Embarassing, as I've been under there to install my barbarians. :dunno:


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## RKT BMR (Sep 7, 2002)

Something I think needs to be said: No modification is risk-free. All changes you make to the car are cost/benefit decisions.

If boosting my engine results in some failure in the future, possibly expensive, a fair question will be, "was it worth it?" An honest answer today for me would have to be that I can't say until it happens. If I get 50k miles out of it before there's a problem, I might feel it was worth it for all the fun I had. Many other people wouldn't judge it the same way.

I'm clearly in the camp that is willing to take some risks in this regard. Others aren't. Both are right. :thumbup:


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## Plaz (Dec 19, 2001)

RKT BMR said:


> *Nate. if you wouldn't mind, could you interpret that pic for me? I'm not familiar enough with what should be there to tell what's failed. Embarassing, as I've been under there to install my barbarians. :dunno: *


Torn subframe. Expensive repair -- definitely not under warranty if a blower is seen by the techs.


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## chukiechz (May 15, 2002)

*Re: wouldnt' touch the current crop.*



pdz said:


> *
> so the problem is the same as with turbos, but these turbo kits are factory OEM engines whereas those are godawful things (i owned one on an S52 M coupe) that have hot start problems, fuel delivery issues, fouling spark plugs, gasket issues....idling issues.....it all is very unpleasant. not to mention the peaky power.
> *


I gotta put my 2 cents in too. I have a stage 2 RMS kit that includes the aftercooler. I have never had a check engine light, spark plugs are normal, idle is like stock. The car passes CA smog with lower emissions than my old 2.5 when it was N/A. Power delivery is smooth and consistant.

I guess my main thing is that the key to drivability is in the tuning. The tuner needs to understands how the DME works, and work with it, not to manipulate it.

That being said, my software is NOT RMS software. RMS turned off my vanos, and the car was running lean. I had mine custom tuned by someone recommended by Jim Conforti. Most of these "tuners" are mechanics that got a hold of some editing software.


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## pdz (Nov 17, 2002)

*fellas:*

fellas:

have any of you driven the new 3.6 litre variocam plus 996 engine? (post 2002 cars)?

it is phenomenal. it has displacement, plus an ability to breathe so the power is everywhere. that engine rips.

if someone presented me with a centrifugally blown 3.0 or 3.2 engine versus that engine, even if i were in the same car, and i didn't have to upgrade the fragile dual-mass flywheel & clutch, upgrade the brakes, and upgrade the suspension parts, i'd still opt for the displacement plus higher revs.

and what is most instructive about this exercise for me has been: the WRX is fun enough and i could tweak it, but none of that would really eliminate the lag. it could keep it the same or make it worse on the way to more power. easy sub 5 second power.

but when that is compared to straight or boxer six cylinder engines....the sixes take the cake and it is sheer grunt while also being able to rev to hold gear. the next hot day in the summer, we'll revisit this question......but i know chuckie's got an aftercooler, but RKT doesn't.


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## chukiechz (May 15, 2002)

IM assuming you're talking about a porsche engine? Im not too familiar with them. But if someone offered me a 911, not even a turbo, for my blown 3.2, Id take it in a heartbeat. 

Is it fair to compare all these different engines though? Its not really comparing apples to apples?


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## pdz (Nov 17, 2002)

*nah, chuck.*

that was the point.

that given displacement plus excellent breathing characteristics, forced induction in any flavor doesn't do as well.

chow, my mein.


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## JST (Dec 19, 2001)

*Re: fellas:*



pdz said:


> *fellas:
> 
> have any of you driven the new 3.6 litre variocam plus 996 engine? (post 2002 cars)?
> 
> ...


Absent artificial limits imposed by sanctioning bodies or taxation authorities, there is no reason to avoid larger displacement if what you want is more power. High specific output engines are interesting, but the engines with the highest specific output (e.g., the S2000 engine) are not necessarily the most fun to drive, most fuel efficient, lightest or even the best performing overall. I would much rather have, for example, a 5.7L LS6 than a 2.0L S2000 engine, in any car.


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## HW (Dec 24, 2001)

*Re: Re: fellas:*



JST said:


> *Absent artificial limits imposed by sanctioning bodies or taxation authorities, there is no reason to avoid larger displacement if what you want is more power. High specific output engines are interesting, but the engines with the highest specific output (e.g., the S2000 engine) are not necessarily the most fun to drive, most fuel efficient, lightest or even the best performing overall. I would much rather have, for example, a 5.7L LS6 than a 2.0L S2000 engine, in any car. *


but in terms of weight, wouldn't a 5.7L v8 be much heavier than the 2.0L i4 vtec that runs at 10Krpm. personally i prefer smaller lighter cars over the "ace'n'gary" type cars with the dragster profiles that rival locomotives.


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## Plaz (Dec 19, 2001)

*Re: Re: Re: fellas:*



HW said:


> *"ace'n'gary" type cars *


:lmao:


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## nate (Dec 24, 2001)

*Re: Re: Re: fellas:*



HW said:


> *but in terms of weight, wouldn't a 5.7L v8 be much heavier than the 2.0L i4 vtec that runs at 10Krpm. *


Who gives a damn about engine weight when you've got more than TWICE the peak torque and easy modifications for more


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## HW (Dec 24, 2001)

*Re: Re: Re: Re: fellas:*



nate328Ci said:


> *Who gives a damn about engine weight when you've got more than TWICE the peak torque and easy modifications for more *


handling would suffer :dunno: i remember reading that the 318is handled better than the 328is because it was lighter.

fuel economy due to weight

the profile of the car ("ace'n'gary" / corvette profile) :thumbdwn:

i remember reading that the s2k was originally supposed to have an inline5 (similar to the one from the acura vigor). but i think they scrapped it because it was too long and heavy.


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## nate (Dec 24, 2001)

*Re: Re: Re: Re: Re: fellas:*



HW said:


> *handling would suffer :dunno: i remember reading that the 318is handled better than the 328is because it was lighter.
> 
> fuel economy due to weight
> 
> ...


Ok, I would take 200 more lb/ft of toque for a few hundred pounds.

A Corvette will take an S2000 in any kind of motorsports event you can think of.


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## HW (Dec 24, 2001)

*Re: Re: Re: Re: Re: Re: fellas:*



nate328Ci said:


> *Ok, I would take 200 more lb/ft of toque for a few hundred pounds.
> 
> A Corvette will take an S2000 in any kind of motorsports event you can think of. *


no doubt there but having to lug around a bigger heavier car sucks and so does the fuel cost. well, then again gas is cheap for you guys in the u.s.. :dunno: so does everyone in the south drive drive pickup trucks, suv's and old muscle cars?


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## nate (Dec 24, 2001)

*Re: Re: Re: Re: Re: Re: Re: fellas:*



HW said:


> *no doubt there but having to lug around a bigger heavier car sucks and so does the fuel cost. well, then again gas is cheap for you guys in the u.s.. :dunno: so does everyone in the south drive drive pickup trucks, suv's and old muscle cars? *


For comparison:

http://www.edmunds.com/new/2003/chevrolet/corvette/z062drcoupe57l8cyl6m/specs.html?id=lin0018

http://www.edmunds.com/new/2003/honda/s2000/2drroadster20l4cyl6m/specs.html?id=lin0018

Z06 is 300lbs heavier, gets better highway fuel mileage. But is massively faster.

And no, not everyone is a *******.


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## Kaz (Dec 21, 2001)

*Re: Re: Re: Re: Re: Re: Re: Re: fellas:*



nate328Ci said:


> *
> 
> Z06 is 300lbs heavier, gets better highway fuel mileage. But is massively faster.
> 
> *


BTW GM purposely designed the Vette to get good highway numbers. It has the 1-4 SkipShift, and it basically idles at freeway speeds in 6th.

Drive both the S2k and Vette at, say, 8/10ths and guaranteed the Vette will guzzle way more gas.


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## HW (Dec 24, 2001)

*Re: Re: Re: Re: Re: Re: Re: Re: fellas:*



nate328Ci said:


> *For comparison:
> 
> http://www.edmunds.com/new/2003/chevrolet/corvette/z062drcoupe57l8cyl6m/specs.html?id=lin0018
> 
> ...


gee, that pretty good. still both cars could lose some weight (3200 for 'vette convert and 2800 for s2k). at 2800lbs, i could see why they decided against the inline 5.

too bad the mr-2 spyder mr-s is not available in canada. only 2200lbs.

do you own a  gun?


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## nate (Dec 24, 2001)

*Re: Re: Re: Re: Re: Re: Re: Re: Re: fellas:*



Kaz said:


> *BTW GM purposely designed the Vette to get good highway numbers. It has the 1-4 SkipShift, and it basically idles at freeway speeds in 6th.
> 
> Drive both the S2k and Vette at, say, 8/10ths and guaranteed the Vette will guzzle way more gas. *


Yea, I don't doubt that.


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## Plaz (Dec 19, 2001)

Emission said:


> *In my garage right now... I have a 993 ('96 911) *


:yikes:

When did you buy that?


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## Emission (Dec 19, 2001)

Plaz said:


> *:yikes:
> 
> When did you buy that? *


My sig has the cars I make payments on. See post above. I wish it was mine!


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## pdz (Nov 17, 2002)

*sorry. didn't mean to stray.*

i would like to add that i drive a turbo everday, make that 7 days a week, and i do love it. it allows for an econobox to absolutely scream.

it is a visceral, undiluted driving experience that requires dutiful shifting to stay in the power, some forethought on manuevers, and extra thought to warming up/cooling down periods.

but no matter how much i enjoy it, two more cylinders just seem so much more effortless from a standstill or low speed maneuvers, be it the S54 or the flat-6. the S54 is a terrific engine because it is a flat power curve; the flat-6 is fun because it has enough cubic inches to have grunt, but it's still quite peaky.

i am still betting that even if the WRX gets its 280hp (believe you me, it will), it will still be a completely different driving experience with more lag and more heat soak ignition retardation.

this is why, to me, at the end of the day, OEM to OEM, i'd still rather have the cubic inches the cylinders and N/A.


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## Rook (Oct 15, 2002)

Awesome discussion, as someone who loves the way N/A motors put out their power its been a good read, but I'd like to say a few things.

1) To the gent who said that his ESS supercharged M54 was more powerful at 2500rpm over stock, I'd love to see you proving that on a dyno. Centrifugal superchargers produce boost exponentially, at 6000rpms, you may be making 9lbs of boost, but at 3000rpms you're making 3lbs of boost. While I doubt you're making 9lbs, you're probably making more like 6-7lbs, which puts boost at 3K RPM somewhere about 2.5-2.7. even less at 2500rpms, probably little enough to even be LOSING power becuase of the parasitic drag from the supercharger. Your powerband is not the same only larger, it is shifted higher, I guarantee it. 

2) Positive displacement blowers, in my humble opinion, are the only way to properly add forced induction to a motor. Turbos are good for ULTIMATE POWER (drag racers), but a Pos. car makes peak boost at all RPMs, never laggy, never waiting for the boost to spool, it simply acts like a larger motor. Done properly, I love a P/D blower. But its difficult to do properly.


3) I would chose a 993 Carrera S or 996 Carrera 2 over any other 911. I love the way an N/A car feels.


My own personal ultimate dream is to put an S62 into my M Coupe. The 5.0L V8 weighs 6kg more than the S52 that is currently in the car, and the weight could be offset with a CF hood. Combined with custom headers and some tuning, Dinan has shown that 475bhp is easily possible with this motor. Thats where I'd tune it and leave it, roughly 400whp. Reliable, solid, consistent, non laggy, POWER.


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## Emission (Dec 19, 2001)

NA aside...

Supercharger vs. Turbocharger.

SC is belt driven off the driveshaft. It can produce boost at idle. There is direct horsepower loss from the accessory drive (SC). As the SC increases in size (more boost), so does the amount of horsepower required to turn the pump. Efficiency runs about 50%.

Turbo is driven by exhaust gas. It produces boost as exhaust pressure increases. There is little (to no) boost at idle. Turbos also cause horsepower loss as they 'choke' the exhuast system. A smaller turbo will cause more back pressure (but quicker boost as it spools faster). A large turbo will cause very little back pressure but require 3000+ rpm for boost (turbo lag). Efficiency runs about 70%.

(There is much more to the story. Read "Maximum Boost" by Corky Bell for more detail)

It is a fact that a turbo is a much more efficient air pump for pressurizing a motor.

Turbo lag, the common complaint, has been nearly eliminated with smaller, lighter, turbo units. My 1.8T will peel-out from a standstill without loading the torque converter!


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## Rook (Oct 15, 2002)

Yes, your K03 equipped 1.8t Will, but chipped, they run out of breath handedly around 4000rpm. I've driven modded 1.8ts.

That is the biggest problem, If you want to get topend power out of a turbo, you either have to have a car that has a VERY narrow RPM band (none that I know of) or you have to put a bigger turbo on. In your 1.8t's case, a K04. One of the 1.8Ts I've driven was a 280whp Scirocco II. Very fast car, tons of topend, but crazy lag. Same with the 650hp Supra I rode in. Lots of topend, laggy lowend. 

This is why I say turbos are good for ultimate power. Drag racers keep the cars in boost 100% of the time, track racers do not. Lower boost turbos that spool quickly and don't have much lag either drop off quickly or don't make THAT much power to begin with. 

That is why I like a positive displacement blower. Since I'm not looking to make 600hp, I'd rather have a posi. on there to give me the most CONSISTENT F/I power I can.

Centrifugal superchargers CAN produce boost off idle, but they are not compressors, they are FANS, (often called hair dryers). At idle/low RPM, with 99% of all centrifugal blower setups, you will not be making any appreciable boost until around 3000rpm. I've had a centrifugally boosted 2.8L V6 (Corrado SLC), I made basically stock power until 3000 to 3500rpm and then started to really pick up and spool more noticeably until redline.

Lysholm makes a blower that is 80% efficient, the most efficient supercharger I'm aware of. Its loud as all getout but it certianly gets the job done. Otherwise just stick with N/A, consistency means everything to me.

I'm basing my comments from someone who drives on the track and doesn't drag race. Turbos are fun on the street and the strip, but not my kinda car on the track. Centrifugal chargers make the same PEAK hp of a P/D blower, but you end up making far less average power. Thats a waste of time to me.

give me a bigger N/A motor, or give me a P/D blower so my motor FEELS like a bigger, N/A motor.


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## Plaz (Dec 19, 2001)

Emission said:


> *My sig has the cars I make payments on. See post above. I wish it was mine! *


10-4. (I turn sigs off at work to make my already obscene listings in the firewall admin's weekly report a little less obscene in turns of KB downloaded)


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## Emission (Dec 19, 2001)

Rook,

I'd have to agree that a turbo does take some work on the track. I'll also agree that a road circuit tends to have the turbo in and out of boost (not a good thing when you are looking for power). 930 vs. 993 on the track, the NA car will win. It is always inside it's power curve, never waiting. My 930 has a K-27. It is great for top end, hopeless on the bottom. 

On a track (road circuit) I'd take displacement over turbo. I'd also take SC over turbo.


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## Emission (Dec 19, 2001)

Plaz said:


> *10-4. (I turn sigs off at work to make my already obscene listings in the firewall admin's weekly report a little less obscene in turns of KB downloaded) *


Too funny. I can only imagine what those traffic reports look like! :yikes:


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## Mashuri (Aug 14, 2002)

Actually, if you want to get into ideal setups, mine would be a strong, low CR motor with a large turbo and computer controlled nitrous. This gives you the best of all worlds. The nitrous is only fed into the intake when initially getting on the throttle. This spools the turbo up instantly and eliminates lag. It also uses your N2O very sparingly so one bottle goes a long way.

Also for you guys complaining about lag. A twin turbo setup really helps reduce lag. One turbo is small to get boost up quickly while the other is large to deliver high pressure at high RPM's. Drive a 996 TT next to a 930 single turbo and you'll find the difference to be night and day.


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## Emission (Dec 19, 2001)

A few minutes ago, I took the 930 for a late-night spin. Outside temps are very low for Los Angeles right now - about 35 degrees. A full moon and dry pavement made a perfect night for a big turbo.

I got on the (basically empty) freeway and let the car's engine oil warm for about 10 minutes as I cruised at 70 mph (staying off the boost). All the while, the large aluminum intercooler was 'freezing' itself in the ambient air. 

A long empty stretch opened up and I dropped the car into 3rd - and floored it.

It shot from 70 - 120 mph in mere seconds. An "E-ticket" ride all the way!  Needless to say, it was an hour before I returned home again....

Conditions like the above are perfect for a turbo. You don't want to hear about the same drive on a hot August night...


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