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View Full Version : Naturally Aspirated or Forced Induction?


Birdman
03-09-2005, 05:24 PM
Was wondering what the general public thought. Me personaly, I go for all natural. Post up you thoughts.

RevShoT
03-09-2005, 05:56 PM
for the longest time i wanted to go forced induction, hell even got about half the parts to finnish the set up

but now reading more on a stroker motor for my car i think thats my new path *th-up*

TiemenT
03-09-2005, 06:02 PM
natural inspired..a natural (V10 from the M5) or a forced (E55)..

you can always go for a supercharger or whatever on the V10.. give you even more power..

Manimillion
03-09-2005, 06:05 PM
natural inspired..a natural (V10 from the M5) or a forced (E55)..

you can always go for a supercharger or whatever on the V10.. give you even more power..

You can always pretend to own stuff as well. *wiggle*

bubsy12
03-09-2005, 07:35 PM
N/A is much more costly to do and doesn't yield the same results as forced induction (ie. Turbo/Supercharger/Nitrous) Plus you can always build your engine/head while boosted and gain more power/torque in the future, or do it right the first time and do the build up first.

Remember that once you fully build an engine up N/A you are pretty near to your limits, if you choose to use higher compression pistons you would have to completely rip the engine apart in the future should you choose to lower the compression to add any forced induction or seriously risk detonation and tuning issues.
Building a lower compression force inducted engine has many advantages in the way of upgrading (ie. bigger Turbo, other Turbo goodies, bigger SC pulley) or you could always just add Nitrous into the mix for that extra umph if you build right.

Do some serious online research and i'm sure you will find benefits of both.

djcontra
03-09-2005, 07:43 PM
forced induction! *th-up*



(ok ok! so i'm biased!!! :D)

Rampage
03-09-2005, 07:44 PM
I prefer Naturally Aspirated, all engine!

But Forced Induction, is quick and cheap(er).

bubsy12
03-09-2005, 07:44 PM
forced induction! *th-up*



(ok ok! so i'm biased!!! :D)

As am I *th-up*

Raging Lamb
03-09-2005, 07:52 PM
N/A or FI...the age old question. Like an all naturall body builder vs a juicer. I respect the natural guy a lot more, while I know what the other is capable of. In the end I'd have to say N/A because I appreciate it more.

bubsy12
03-09-2005, 07:56 PM
I'd have to say in defence for alot of F/I guys... there is alot of similarly respectable research and puzzle-piecing needed to be done in order to build a lower compression engine for boost. The majority of guys these days may just throw a Turbo-Kit/Supercharger/Bottle on their cars and call it a day, but for a serious enthusiast there is alot more to it.

///MsAniTy
03-09-2005, 08:16 PM
Depends what u wish to do. i would go for a turbo kit if i wanted speed and all but if i wanted to track the car then i would go all motor

bubsy12
03-09-2005, 08:20 PM
I agree it is all dependant on your intentions.

If you are referring to a road track i'd probably go for mid-compression build up with a smaller quicker spooling turbo, or SC which power is always there with.

RevShoT
03-09-2005, 08:25 PM
ide have to disagree on the price, ive been looking into a stroker motor and i can get an s50 crank and rods for 300 US

bearings would run me 60 bucks and the gaskets to re-seal the engines are 250 for the bottom half (includes new piston rings ect..) and get the chip from AA for their stroker kit

thats it!

plus you will have the satisfaction of knowing you got a fresh re-build on your bottom half

btw a 2.9L motor will out perform an M motor :) and have similar #'s and u can bring the redline higher

add headers and a few other goodies and u can achive 300 N/A horses!

tlaselva
03-09-2005, 09:44 PM
N/A and FI?
The old age question.
Both have their advantages and disadvantages.

Which one would suit you best is best answered by you, with answering a simple question or two.

What is your primary goal(s) for this car?

Track duty?
Strip duty?
Highway pull monster?
Dyno & Garage Queen?
How important is reliability i.e. daily driver or Saturday night toy?
How deep are your pockets?

Quack
03-09-2005, 10:42 PM
for the longest time I was a N/A fan, it's real raw power, but after looking at my wallet it would be so much cheaper to go F/I

paul christians
03-09-2005, 10:50 PM
N/A strocker high comp 10.5 to 11.5...............F/I strocker 8 to 8.5 comp........ *par-t* *par-t*

paul
03-10-2005, 08:46 AM
for the longest time I was a N/A fan, it's real raw power, but after looking at my wallet it would be so much cheaper to go F/Ijust go FI. it's the only way to go. just look at the guy on bimerforums with the same setup i have just he is running a bigger turbo. on a 328 he made i think it was 462rwhp. thats to the wheels. do u see the money that would have to be spent to an all motor to get thise numbers... :huh?:

AMG_POWER
03-10-2005, 09:36 AM
after i drove N/a for long time, and now tried F/I i say F/I ALL the way!

Furious
03-10-2005, 09:51 AM
i like the idea of N/A but forced induction is like just that much easier to do IMO.

Mitch555
03-10-2005, 09:56 AM
Nothing hotter than a high hp high torque N/A engine!

Furious
03-10-2005, 09:57 AM
Amen

EMPOWERD
03-10-2005, 10:05 AM
The way I see it, if you're striving for numbers over 400... then FI definitely makes more sence (reliability-wise). Also, with large displacement comes weight-unbalancing the car's dynamics. Sure, you might like the torque of a 460cuin big block, but what are you going to put that in? Under 400HP, NA is hard to beat with it's crisp throttle response and smooth/efficient power delivery.

///Maluco
03-10-2005, 10:29 AM
I agree...big motor=more weight.
I've driven both N/A and F/I high horse and torque vehicles from big block Chevy's and Bimmers to turbo lightweight Datsun's and I like them both. They'll all give you the big smile from ear to ear. :D
There's nothing like the torque feeling right off the bat in a N/A, but when you hold onto the wheel in a F/I small car...holy smackers....it sure is a ton of fun too.
Keep in mind that the F/I car needs some extra car in the heat department because a turbo can generate some serious heat :) and in summer driving (you know...when you're trying to smoke everything on the street that moves) you'll need to be more respectful to the motor, especially if you don't have all the necessary cooling required for those "spirited driving" moments.

GEEE$
03-10-2005, 12:54 PM
It's virtually impossible to beat forced induction. It's cheaper to acquire the same output levels, can be just as reliable as any N/A-built car when done properly, and the power output is unlimited. N/A motors are wonderful animals...but once you've driven, or been driven in a force-fed car putting out high boost, the feeling is beyond words.




G$

ara325
03-10-2005, 01:04 PM
I guess it's a question of satisfaction with your current power...personally, after driving a few turbo'd cars i.e. Eagle Talons, Mazda GTX, e30 325 turbo, VW 1.8T, I would say that i'd go F/I...primarily turbo...it's jsut so much more fun when the powerband really kicks in. *th-up*

tlaselva
03-10-2005, 03:08 PM
The way I see it, if you're striving for numbers over 400... then FI definitely makes more sence (reliability-wise). Also, with large displacement comes weight-unbalancing the car's dynamics. Sure, you might like the torque of a 460cuin big block, but what are you going to put that in? Under 400HP, NA is hard to beat with it's crisp throttle response and smooth/efficient power delivery.

A few years ago, I would've agreed with you.

In the last several years, you'd be suprised what current technology can do with the Aluminum block LSx series engines these days.
In New Jersey, there is currently a street legal 647 HP N/A 447 ci motor built by ECS, that weighs ~20 lbs. more than my stock LS6.

And FI will never be as reliable as N/A.
Ask any engineer he will tell you that the fewer parts a machine does to get the same job done the better. This also of course lowers build/operating costs considerably.

Additionally, the power band of a N/A motor is ideal for strip and track racing.
Makes power delivery much more predictable and manageable.
Ever wonder why BMW refuses to go FI on their M series cars?

SickFinga
03-10-2005, 03:20 PM
And FI will never be as reliable as N/A.



I think it also depends on the level of tuning.

A highly tuned, high compression, high revving NA, wont be that reliable either.

I really dunno, but I think a 400hp m52b32 NA vs 400hp m52b32 FI, Id say FI will be more reliable.

But yeah, big engine no longer means heavy and gas guzzler.

thinair
03-10-2005, 06:05 PM
I've been thinking this question also. What to do, which route to do. I'm a huge fan of NA, I love very fast engine response, but it does cost more to get a high HP NA motor, and you don't get the torque (generally anyway.)

I've been dreaming up a few setups in my head, ranging just from swapping in a 3.2L, to building a weird 3L setup (2.8L block, 3.2L crank). But I have also been thinking a lot of FI, but primarily a roots blower. I don't think i'll ever consider a centri or a turbo. But the cost of a twin screw at the moment are so expensive that I'd rather just hold off.

EMPOWERD
03-10-2005, 06:40 PM
A few years ago, I would've agreed with you.

In the last several years, you'd be suprised what current technology can do with the Aluminum block LSx series engines these days.
In New Jersey, there is currently a street legal 647 HP N/A 447 ci motor built by ECS, that weighs ~20 lbs. more than my stock LS6.

And FI will never be as reliable as N/A.
Ask any engineer he will tell you that the fewer parts a machine does to get the same job done the better. This also of course lowers build/operating costs considerably.

Additionally, the power band of a N/A motor is ideal for strip and track racing.
Makes power delivery much more predictable and manageable.
Ever wonder why BMW refuses to go FI on their M series cars?

I kept you in mind when I wrote that response Tony. Not everyone can shoe-horn any V8 into their car (ie: Sport Compacts) regardless of size. I think a good weight for a decent (RWD) sports car should not exceed 2800lbs. That said.. you don't always need displacements over 4000cc to get decent power when using FI (which is exactly what I'm talking about) for moving an agile-sized car (ie: Lotus Exige). A 3100lb Vette is in a whole different ball-game with NA motor options coming from every-town USA. I think this thread (question) is really posed for imports.

Birdman
03-15-2005, 01:08 PM
Looks like a pretty even line between NA and FI. I have to say, didn't expect that. I thought more people would have lended towards NA but looks like a lot of you enjoy the turbo.

JazzM
03-15-2005, 01:53 PM
Naturally Aspirated 100%. Went the FI route, blew the motor. Hence reliability is an issue... much more stress on the engine components, along with many more parts that need to be maintained. Rescently swapped an S54 (e46 M3) motor in my car and I will never go back the FI route. The throttle response is second to none, the high revving engine is both reliable and produces ample power.

Also, look at the new M5/M6 motor, V10, 5.5L with silk-smooth power and response. No turbo lag, no restrictions on RPM as with other FI applications, 9000+ RPM redline and a LOT of power.

Best regards,

T.

Jon@Bimmersport
03-15-2005, 02:07 PM
ide have to disagree on the price, ive been looking into a stroker motor and i can get an s50 crank and rods for 300 US

bearings would run me 60 bucks and the gaskets to re-seal the engines are 250 for the bottom half (includes new piston rings ect..) and get the chip from AA for their stroker kit

thats it!

plus you will have the satisfaction of knowing you got a fresh re-build on your bottom half

btw a 2.9L motor will out perform an M motor :) and have similar #'s and u can bring the redline higher

add headers and a few other goodies and u can achive 300 N/A horses!

dont you need 3.2L sized pistons, as well to bore the cylinders to fit the pistons?

and it really depends on the engine, but most likely 90% of the answers would be turbo, or S/C.

JazzM
03-15-2005, 02:37 PM
No, you don't, 2.9 is a stroked 2.5 with a 3.0L (95 M3 US) crankshaft and connecting rods... bore does not change (stays at the stock 84mm).. Altough getting 300 NA crank hp would not be that easy task (you will need to PnP, change cams, bigger injectors, larger AFM, intake, headers, no cats, etc..

T.

AMG_POWER
03-15-2005, 06:17 PM
Naturally Aspirated 100%. Went the FI route, blew the motor. Hence reliability is an issue... much more stress on the engine components, along with many more parts that need to be maintained. Rescently swapped an S54 (e46 M3) motor in my car and I will never go back the FI route. The throttle response is second to none, the high revving engine is both reliable and produces ample power.

Also, look at the new M5/M6 motor, V10, 5.5L with silk-smooth power and response. No turbo lag, no restrictions on RPM as with other FI applications, 9000+ RPM redline and a LOT of power.

Best regards,

T.

M5/m6 engines are 5.0 and 8.200 rpms!

M10-Power
03-17-2005, 10:43 PM
I kept you in mind when I wrote that response Tony. Not everyone can shoe-horn any V8 into their car (ie: Sport Compacts) regardless of size. I think a good weight for a decent (RWD) sports car should not exceed 2800lbs. That said.. you don't always need displacements over 4000cc to get decent power when using FI (which is exactly what I'm talking about) for moving an agile-sized car (ie: Lotus Exige). A 3100lb Vette is in a whole different ball-game with NA motor options coming from every-town USA. I think this thread (question) is really posed for imports.


LSx powered E36 is the same weight as a 6 cylinder E36 with the weight balance of a 4 cylinder E36.

Doesn't require a shoe-horn either ;)

Hard to beat the LSx engine for power delivery in an E36, even harder to beat the sleeper effect.

Bimmerfest in Calgary will have 3 or 4 of these cars if anyone wants to come see them.

Since he was posing this question while looking for a '97 M3, I'd assume he was refering to the E36 for the NA vs FI question.

BigD
03-17-2005, 11:35 PM
natural inspired..a natural (V10 from the M5) or a forced (E55)..

you can always go for a supercharger or whatever on the V10.. give you even more power..

It's beyond me why everyone assumes this. It's like some general stigma out there that a FI motor is just a poorly designed NA one. It's NOT. You can't just slap on a blower or a turbo on a NA motor. It will blow up!!! There are a LOT of considerations that must go into a well designed FI engine and guess what? What you have to worry about for an NA motor is there too, but there's a lot more in addition. For instance compression. To get a lot of power you need a lot of air density. You can get that by just jacking up the compression on an NA motor OR, you can artificially condense the air at a critical time. The former stays constant, you have a fixed compression figure to design the structure around. The latter however, is variable and you dont know precisely what boost characteristics you will choose until you are done. It requires knowledge and experience to predict it and design the motor accordingly. Then the forced induction system itself has to be properly designed.

Long story short, to me, an FI motor that lasts is a hell of a lot more impressive than an NA one if both motors are jacked. Certainly, I'm not going to compare the new ///M V10 to a typical turbocharged Volvo motor. There's definitely a greater feeling of accomplishment in getting all that power via motor only. But a properly tuned FI engine will be producing a lot more effort and I'd take that instead. Unfortunately, there are very few of those. Most people just take an engine that was never designed for forced induction and then have to fix all sorts of problems.

All that being said, my S38 is one of the greatest engines ever built so :moon:

BigD
03-17-2005, 11:46 PM
Ask any engineer he will tell you that the fewer parts a machine does to get the same job done the better.

The only problem is that an FI head does not need to be nearly as fancy as a stacked NA one (like the current ///M designs). Hell you could simply go with an overhead valve design, forget variable timing. And a turbine is basically indestructable. So I would even argue that an FI motor is actually less complex and hence more reliable - if designed that way from the ground up, and the FI bits weren't added outside of the factory onto an NA motor.

tlaselva
03-18-2005, 01:16 AM
The only problem is that an FI head does not need to be nearly as fancy as a stacked NA one (like the current ///M designs). Hell you could simply go with an overhead valve design, forget variable timing. And a turbine is basically indestructable. So I would even argue that an FI motor is actually less complex and hence more reliable - if designed that way from the ground up, and the FI bits weren't added outside of the factory onto an NA motor.

Have to disagree with you BigD.
A N/A motor will always be more reliable, dollar for dollar.
Now mind you, I'm talking in regards to the Domestic V8 scene.
Over the past year, I've talked to some of the most well respected engine tuners in the states, where all these guys’s do is build engines, N/A and FI'd for track duties.
They all had the general consensus that it was a given fact that N/A is the way to go if reliability is of concern, or you competitively race.

Take for instance, East Coast Supercharging. One of the largest and well respected F/I'd specialists in the States. They've built everything from H/C cars to 4 digit HP monsters. Over the past 15 years, he's had Turbo, S/C and N/A'd cars for his personal vehicles. His last 3 motors have been N/A motors. His current car is a 447ci V8, with over 550 rwhp.
To make a long story short, he found N/A cars are much more reliable. And this all coming from a FI'd specialist.
I was originally going F/I myself, but he talked me into a N/A motor.
Don't even take my word for it. You will find in the States where 1/4 mile and track racing is a serious business, there are very few F/I'ed cars compared to N/A motors. That alone should speak volumes.

Now like I mentioned before, making big power out of a V8 is relatively available.
If your car of choice is a 4 or 6 cylinder, FI becomes a necessity.

BigD
03-18-2005, 01:45 AM
Well the dragstrip is different. There you can choose between forced induction or nitrous, can't have both. And in that case I'd choose nitrous too, much less guess work, easier to fabricate, more reliable and greater effect.

That being said, I am not referring to tuners, rather engine manufacturers. When you compare two more or less equivalent powerplants (I'm not going to compare a 500 hp NA big block and a 500 hp blown 2.3L 4 banger), the way you extract the power out of them is much more reliable the FI way - IF you are designing the engine yourself with that in mind. To get the most out of a motor naturally you have to go maximize the power you can extract from combusting with the air that's available to you and to do that you need to compress the shit out of it and because of that, you need to do so very very quickly and often to do a lot of work (hence high rpm). As a result, you are looking at a design that is ALWAYS stressed, at any rpm, and its working range is also extremely high velocity where everything has to go perfectly or else...catastrophy. Now, a FI design on the other hand is only required to bare a lot of stress under boost. The rest of the time it is a very relaxed setup. Yes, the stresses on the engine will be very high but that has nothing to do with it being NA or FI, that's the name of the game - producing force. The difference is I don't necessarily have to worry about breathability and proper timing at radically different rpm ranges (ie having a cam for 0-6000 rpm and one for 6000-10000). I can shove all the air I need in there at any rpm I choose. Therefore I can make my big power figure by jacking up the other variable in the equation - the torque (whereas with NA you are trying to maximize the speed, rpm).

NOW, what you are getting at, what we've discussed at length before, is not NA vs FI, but rather cubic inches. And there I have no argument. I will take the LS7 over a blown or just NA jacked 3 liter any day. THe S54 vs LS6 is the perfect example. The latter being smaller (wider yes but shorter and hence requiring a smaller or at least equivalent eng. comp.), lighter (iron vs alu), stronger, cheaper, less complex (hence more reliable) and better balanced.

Frank de Jonge
03-18-2005, 09:28 AM
Natural Apirated all the way :)

GEEE$
03-18-2005, 01:35 PM
[QUOTE=tlaselva]Don't even take my word for it. You will find in the States where 1/4 mile and track racing is a serious business, there are very few F/I'ed cars compared to N/A motors. That alone should speak volumes.
[QUOTE]


I have to respectfully disagree with that statement.

If you are speaking of american cars solely, I can agree...but on a whole, that's simply not the case, especially when you mention the word Import.

I cannot even begin to count how many Supras, RX7's, EVO's, 300ZX's, WRX's etc running huge turbos at the track all over North America, for serious business(meaning dollars!!!). It's virtually a plague.





G$