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Old 05-15-2000, 04:36 PM   #1
rrsettgast
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Post Staying NA with New Cams vs Turbo

I have been noticing that a lot of members have expressed interest in staying NA, and installing aftermarket cams (I may have said this a while ago too). The stated reason is generally something like:
"I don't want the hassle of adding a TC to my car."
I have been thinking about this logic, and I can't see how the argument for going to aftermarket cams makes any sense. I could be very wrong, but Reasons following:
1) With an aftermarket cam, you are replacing a part of you engine. This involves major engine work...doesn't it? So much for "no hassle"!
2) If you replace the cams, the stock ECU will get all confused...won't it? You will still be stuck with a bunch of piggyback controllers, or perhaps a programable ECU. You still have to spend a large chunk of time tuning the engine to get it to work right.
3) A turbo and cam do essentially the same thing, which is to increase flow. A new set of cams will change the valve intervals to acomplish this, while a TC just increases the intake pressure to get there.

So what are the advantages with staying NA and replacing cams again??

Randy
Please correct me if I have any misconceptions
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Old 05-15-2000, 06:03 PM   #2
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In regards to your 3 reasons that N/A is not a good idea....

#1) As we all know, the current 2.5RS has a Phase II engine, which is SOHC. The cams are easily accessible from under the valve cover. I wouldn't define that as major work, but some people may. Of course, you have to remove the timing belt and some other miscellaneous stuff, but it's not that big a deal. I wouldn't go so far as to say it's more work than installing a Turbo, that's for sure.

#2) It depends on how "radical" your cams are. If you have a lot of overlap, certain vacuum signals are going to be out of range for the stock computer and errors will occur. However, a mild cam upgrade shouldn't post any problem, and I'm sure companies like Rallispec realize this and is the reason they have not released any cams as of yet.

#3) A cam doesn't change "valve internals" it merely alters the timing events as to when each valve opens and closes. By optimizing these values, you can optimize the power output of the engine. The Turbo just "force feeds" air into the system, thereby bypassing the valve timing. However, a camshaft that is ideal for a turbo is not ideal for N/A. The reason the 2.5L responds so well to turbocharging is because the stock cam is almost ideal for a turbocharger. This is great if you want to go turbo, but for N/A, it means the engine is GROSSLY undercammed.

I still believe, that with the proper mods, 200+hp can easily and reliably be produced by the Subaru 2.5L in N/A form.

Some Advantages to staying N/A route:

1) May not void your warranty. Just the installation of a TC voids it from what I can tell.

2) Much easier to pass smog checks if you don't have a big blowdrier taking up engine space.

3) Much cheaper to install, since you don't need all those aftermarket doo-dads to keep detonation in check. You don't need an Intercooler, piping, special computers, etc....

4) Easily removed if there is a problem, since most N/A mods are bolt on mods.


Dave
'00 2.5RS Sedan
'72 Datsun 240Z
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Old 05-15-2000, 06:28 PM   #3
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Thats "intervals" not internals!!!

Randy
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Old 05-15-2000, 06:56 PM   #4
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Randy,
Actually my dream is scrap as much of the EFI and engine management system and get this baby running off of a crank fire ignition and Webers. At that point I can run as much overlap as I want and rev the motor until it spits a rod.

I would like to eventually build-up a used phase 2 this way, maybe even using the DOHC heads. I think with some more compression 230hp is not at all unreasonable. And you get too look down the throats of those Webers every time you open the hood. I would keep the stock motor in the garage for back-up and inspection.

I am a not-so-old fart who thinks turbos are inelegant

Tim
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Old 05-15-2000, 07:57 PM   #5
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Well cams aren't going to run you 4 or 5 grand and for most people 200-225 hp is just what they need most people aren't looking for 250-350 hp. The cost of running a high boost engine can get a bit excessive especially for someone who wants a daily driver as well. Cams are a mild performance upgrade that when selected carefully can get you over the 200 hp barrier that the RS runs into.

Chris
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Old 05-15-2000, 07:58 PM   #6
Joel Gat, 1.8L
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Quote:
get this baby running off of a crank fire ignition and Webers.
...
I am a not-so-old fart who thinks turbos are inelegant
Hello,

AHAHAHAHAHAHAHAHA. Damn, I fell off my chair reading that. Anyone who thinks carbs are "elegant" has not looked under the hood of a car in at least 15 or 20 years. The only people still using carbs are people who learned the trade before fuel injection worked decently and who now refuse to grow up with the times. Let's see, you have two choices. One, you can open a door and dump some random amount of fuel and air into the engine and fine tune it to plus or minus 5% or Two, you can squirt in the exact amount of fuel necessary for the exact amount of air you allow to enter the engine plus or minus maybe 0.01% (using flowbenched RC cams to compare to the Webers).

Oh man, that was a funny post.

And back to Randy - if you change the cams, you can use the stock ECU in much the same way as you can with a low pressure forced induction unit. Of course, you can use a more radical cam than "radical" turbo before needed a new ECU but that's because a radical cam doesn't change flow as much as a mild turbo. Once you get drastic enough with the cam to get real power, of course, then you need a stronger spark, more fuel, new timing, etc etc etc. To get to the same hp numbers would basically take the same ECU mods.

Obviously this isn't perfectly true, but it's close. To get to the same point in power, though, aside from mild increases, the turbo is going to be cheaper. Yeah yeah, for right now, turbo kits are stupid-expensive for our cars, but to "cam" your car to 250 hp is going to cost you dearly. The NA way to get there is going to involve a new valvetrain to support high rev limits, and other internal work, including probably new pistons, etc.

For mild power, like 200-220 hp, cams will be the cheapest way to get there. The cams are simple to change on the subaru. Pop off the valve covers, pull off the bearings and drop the cams out. It's a bitch to reach, but I bet even with the engine in the car, it could be done in the same time as a turbo install. Of course, the cams will need to be supported for that kind of power with an intake, exhaust, headers, hiflo cat, etc.

JYD
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Old 05-15-2000, 08:15 PM   #7
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I couldn't agree more with you guys. My Subaru is the daily driver/commuter and going Turbo is just too expensive for what the cars intended purpose is going to be. I'm one of the people that would be perfectly content to have "just" 220hp in my daily driver. It may not win all the races, but that's not why I bought this car. The Z fills my racing appetite quite nicely already.

Maybe that's the purpose of staying N/A; A farily cheap and easy way to get 220hp? The hp potential of going N/A is obviously much less than any forced induction, but like Joel said, it shouldn't cost you a fortune to get 220hp if that's what you're after. The turbo has much more potential, but it also costs a lot more $$$. I think you can buy all the stuff I need for a 220hp 2.5L N/A for less than half the cost of a Turbo. That has yet to be proven, but I see no reason why not.

rrsettgast-Sorry, about the internals vs. intervals. Must have read that a bit too quick and didn't notice the "v" instead of a "n".

Dave
'00 2.5RS Sedan
'72 Datsun 240Z
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Old 05-15-2000, 09:01 PM   #8
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Eeeewwww! Carburetors are yucky!!!
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Old 05-15-2000, 09:14 PM   #9
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I dont know, but i really think the potential of getting any serious gains out of a SOHC engine with cams wouldn't be that great. The 98's should benefit a lot though from it.

If someone can pump 220-240hp out of a NA engine for half the cost of the turbo, definately let me know! Im in for sure :-)
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Old 05-16-2000, 12:16 AM   #10
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Talking

whenever there is N/A posts I am there!!!

first a set of downdraft carburators on a classic Testa Rossa are a thing of beauty! I dare anybody to say any differnt!! haha

the thing about carburators is that you actualy had to know something about cars to tune one! No bolt on and let the computer learn it... you had to know about every part intimately... please tell me you can respect that guys! I know some people think its old school junk, but its not.. its pure skill.. its really very sweet to have a car with a properly tuned carb on it...

moving on...

The 2.5L is not unlike any other engine out there. I know that you guys are going to kill me but its incredibly close to a typical American V8 in its characteristics.

Lots of low end umph.. and runs out of breath up high. A mild cam is exactly what the doctor prescribes to fix this. Nothing radicle but just a few bumps over stock should be done with bolt on ease. This is of course if the piston to valve clearances are good and things of that nature are researched.

I will be on the lookout for a cam and I will buy it very quickly if it proves worth its salt..

later folks

SCRAPPY
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Old 05-16-2000, 12:52 AM   #11
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Scrappy, good work on your defense of a carbuereted Italian classic. There's nuttin like the growl of multiple webers on an Italian engine. You almost cant call yourself an enthusiast if you cant appreciate that..

A medium grind set of cams, decent headers and exhaust finished off with decent engine management would make for one nice running RS.

Very driveable with minimal reliability concerns as well.

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Old 05-16-2000, 06:46 AM   #12
HRE | giulio
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it's 8:48 am EST... I'm reading all this and getting a stiffy.

I want cams now! and headers, hiflo cats, exhaust, etc etc etc.

since i got a 98, will i have to spend 2x for the cams? prob... are the cams the same though?
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Old 05-16-2000, 07:31 AM   #13
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Joel,
If carbs are so bad, why do many FI 911 owners remove the EFI system only to add webers, when they put the car on the track. And why does that conversion bump you up in class at PCA events. I would assume Porsche has a very sophisticated engine management ssystem.

I agree that it is less accurate, but webers are accurate enough, really easy to tune, and make very good power. Also using carburators opens up the possibility of using very high overlap that would confuse even modern EFI systems (never idle right). Plus I don't need a laptop to tune the thing.

I am not a computer guy, actually, except for stereos (which I use vacuum tubes) and TV's, I hate electronics. With webers I can change primary and secondary venturi sizes, emulsion tubes, idle jets, main jets and auxillary jets. They can be tuned for any motor and easily retuned for any mod. They don't run as clean but I am about as far from green as you are going to find.

Most of the reasons everybody switched to FI were for milage and emissions considerations. I don't think any car would pass current emissions with a carb. The early systems sucked, but I agree the modern ones have good performance potential.

I would rather find mechanical as opposed to electronic solutions, but that's just me. I prefer that my car has only one brain and that it is located in the drivers head. Then again I still use an 5lb, old manual, Nikon from 1979 and have no desire to buy a digital, autofocus, auto exposure piece of plastic. (A camera is only as good as its lens).

Before you write carbs off, drive a 2.0Liter 911S (90hp per liter with carbs).

Tim

And I still think there is nothing pertier in an engine compartment than polished velocity stacks.

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Old 05-16-2000, 10:04 AM   #14
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velocity stackts...

oh oh.. grunt..

you are soooo right Tim!

Scrappy
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Old 05-16-2000, 10:17 AM   #15
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Carbs may or may not be the answer in this case, but don't knock them. With proper tuning, they can really perform. I feel the Holley's and other such carbs are not as flexible as the more "exotic" brands such as Weber, Mikuni, etc...There's just not a lot of tuning that goes into a Holley which is basically just a fuel dumping device. The exotics on the other hand, well that's another story. There is more of an "art" to tuning multiple carbs than there is for programming a fuel-injection system. With Fuel-injection, there are multitudes of sensors giving you feedback on what the engine is doing. And yes, you can tune more precisely because of that. All these technological gizmos don't exist on older carbureted machines, which makes the "art" of tuning multiple carbs that much more amazing or what some would call "black magic".

The only drawback to carbs, is that you have to tune for a specific rpm. If you want high rpm power, you need to sacrifice low-rpm driveability. You can't "have your cake and eat it too" so to speak. But with carbs, you can get MUCH more cfm at high rpms than you can with a single throttle body fuel-injection system, which is why people switch to them for race applications. I'm sure if someone went through the trouble to mount a couple IDF Webers on our 2.5L with a good cam set, this thing would scream until it threw a rod.

My Datsun has triple 45mm Weber DCOE carbs installed and it SCREAMS to it's 7500rpm redline. I can run the 1/4 in the mid 13's with 0-60's in the 4's. All this in N/A form. Of course the engine is somewhat of a dog out of the box, but once it revs, and with a close ratio gearbox, you can't beat it except for top-speed.


(Pic of my current 3.0L Rebello with triple 45mm DCOE carbs and ITG racing filters)

My Subaru is only my 2nd fuel-injected car. All of my other cars (VW's, Porsche's, Datsun) have been carbureted, so I may be biased.

Dave
'00 2.5RS Sedan
'72 Datsun 240Z
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Old 05-16-2000, 10:50 AM   #16
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Keep all this N/A talk coming !

Boomer
98RS
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Old 05-16-2000, 10:58 AM   #17
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Hmm all I know is this, the fastest NA 16v VW's run Webber sidedrafts. The first thing tuners do is rip out the CIS injection. Carbureted motorcycles still tend to perform much better than fuel ingected ones. I suspect this a lack of R&D though.
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Old 05-16-2000, 11:39 AM   #18
HRE | giulio
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Are cams possible on an RS, still keeping the stock ECU?
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Old 05-16-2000, 11:53 AM   #19
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Sure they are as long as you dont want a huge duration and big valve overlap.. what you want is a simply streetable cam. Just a little over stock lift and a tad more duration.. A huge cam gets into chassis dynamics problems.. you have to have low end in our cars. It weighs too much and has a hell of a lot of drivetrain to get through. You need low end to keep our cars punchy at low rpm. But all we need is a little more up top.. I dont care to rev it to 7000, it can stay at 6250 as long as it is strong up to 6250... and does not fall off like our stock cams do...

but sure you can get away with a mild cam.. I dont see why not...

SCRAPPY
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Old 05-16-2000, 02:29 PM   #20
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Joel,
We could argue back and forth on this for a while. As for the 2.0liter S vs. CIVIC SI motor, there is no comparison, the S motor has some torque, not alot, but some, and I can go to even hotter cams and bigger valves and bigger venturis and take it up past 210hp (and it is a Porsche from the days when they were handmade).

As I said before this is a personel choice. I am not interested in making a laptop part of my tool box. If I eventually get one, it will be for games and DVDs.

I prefer the look, sound, smell and yes performance of carbs. Of course if money were no object, I wouldn't buy a Skyline or a 22B or S2000, I would buy a 73911 RS or Ferrari 512BB (I think TR's are ugly with those big gills) or an E-type Jag, Hemi Road Runner, Boss 429 Mustang.

I like mechanical things, I like to see that this pushes on that, and makes this go around, that bumps this and makes that open. It reminds me of the game of mousetrap when I was a kid. Mechanical relationships have always made sense to me, they follow a visible logic, whereas a computer follows an abstract logic (you need a special tool to view the logic).

The problem with having an ECU doing all that, is that it is invisible to me, I can't see whats going on and intuitively adjust or fix it. Its like a magic box that controls your motor and I don't feel like going to magic shool. If I have to I will, but for now why go out and learn voodoo to dispatch my enemies, when I have a trusty baseball bat that has served me well for 20 years. you can argue that voodoo is more efficient, but my baseball bat works and I know how to use it. When my baseball bat doesn't work any more, then it's time to learn voodoo.

Remember the catalyst for automotive technological change has not been incresed performance, but ever increasing regulatory hurdles. If the evolution had been a natural progression led by market demand for better performing cars I may feel differrently, but the paradigm is that the government imposes technological change to fit design paramaters that I don't give a monkey's a$$ about (emissions and milage). Just like the switch to transistors was originally to make electronics smaller and maintainence free, not better performing.

Someone else is imposing design parameters that I don't agree with on products that I buy. No one ever asked me about CAFE and CARB. No one asked me what audio data is not important and can be thrown out when compressing analog recordings into a digital format.

PS keep your Minolta, especially if you have a bunch of lenses. See how many of the current digital cameras will still be usable in 30 years.

Peace,
Tim
lover of Tubes, Carbs, KodaChrome, leaded gas and baseball bats

PS: Joel, I still use Campy Delta brakes on my road bike (Steel Colnago) because they are beautiful, even though they are heavy, a b**ch to set up and maintain, have a reputation for being dangerous and are easily outperformed by modern dual pivots. You are dealing with a very stubborn man, who prefers to use his heart rather than his head.

I figure this analogy will make some sense to you since you said you used to race. Deltas are the C-Record brakes from about 88-92 that looked like polished silver bells. Most pro's and mechanics hated them, but they are gorgeous.


[This message has been edited by boxerman (edited May 16, 2000).]
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Old 05-16-2000, 03:04 PM   #21
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Well Joel the opinionated.. You sure are a big fan of fuel injection! I will give you that. And for some reason you have a bitter hatred for carburetors. The movement to fuel injection was inevitable. With the smog and emission laws making vehicles run leaner and leaner to improve mileage there was no doubt in the carb was running on borrowed time. The problem with this is that it has spawned an entire generation of bolt on superheros! The thought of going into and engine and actual do work to internals… <gasp> perish the though.. lets instead undo three screws and put on an intake instead. Kids now just purchase a super black box made by some body else that magically does this or that…

Want to advance your timing, buy this superbox…

Want to run your fuel more rich.. we have a superbox for that too….

We are turning into an entire breed of plug and play tuners that know nothing about the workings of an automobile… just put in this super box and it will make 200 HP.. oooh aaaaaah.

Sure I think the ability to adjust the fuel injection with a button is rather cool.. and I happen to like fuel injection (surprise!, surprise!). The fact of the matter is that you can get more power out of fuel injection. I never denied that.. never will.. if top fuel dragsters run fuel injection.. then its obviously the way to go…but I do still admire the simplicity and effectiveness of carb(s) too.

To say you cant tune an engine with a carb is ignorant. You said it yourself, they worked quite well for 70 + years. People often criticize things they don't understand. People don't tune engines anymore.. computers do… It was in fact an art to get a race car to run with 8 carbs. I am disappointed that you can appreciate the skill it required.. older tuners did not just bolt it on and let it run and call it tuned…they had to use air/fuel mixture guages, vacuum guages, fuel pressure, etc.. you know, everything that the computer does for you now….. so you don't have to know anything .. just wonderful ignorant bolt on bliss…

I will concede that a carb it not as accurate as fuel injection…. With that I cannot put any argument against your statement.. you are correct. But a carb is not caveman inaccurate either…

Now there is a new breed of new car tuner immerging. Although they are very rare indeed. I got my eyes opened to just how much control we can have over our ECU''s when I saw Shiv tune a guys car with his laptop.. this was impressive to say the least. I can respect that … it requires intimate knowledge of all variables involved. When you look at it.. things have not changed that much… just the tools to complete the job have.

I simply love the sound and feel of a carburetor, and I enjoy the simplicity and hands off tuning ability of fuel injection… I have learned both and understand both. To understand the workings of past cars helps to tune the new ones…..Just because its older does not mean its junk..

And that's all I have to say about that… (for now hahah)

SCRAPPYDO
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Old 05-16-2000, 03:13 PM   #22
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What an awesome discussion! I have to say I have learned a lot from all of it.

I have both a 1972 MG Midget (all 1275cc of it) and a 2000 2.5 RS. Would I like to see carbs on the Impreza? Sure! I understand what others are saying about wanting to "see" the magic that happens in the engine. And oh yes, do velocity stacks just look BAD ASS. But hey, we all have our opinions huh?

My MG has Webers. Oh yes, I love them. The Subaru is FI. Damn I love that too. I think the most important point here is that we all have different thoughts and ideas, and applying those to our cars is what makes this club so great. Not to mention it is a great forum to discuss these ideas...with intelligent thoughtful people.

Am I going to get a turbo or go N/A? Honestly I don't know. But for now I will keep the Webers on the MG and the injectors on the RS. That is, unless I swap engines....and drivetrains....hmmm....all wheel drive 165 hp MG Midget? Oh my....

D. Neil Crawford
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Old 05-16-2000, 03:54 PM   #23
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I think fuel efficiency and emmisions go hand and hand with performance. Correct me if Im wrong but if an engine burns cleanly it also makes more power.

If all the fuel was burned in the combustion cycle wouldnt that be clean and more powerfull.

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Old 05-16-2000, 04:03 PM   #24
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COZ

two words..

Honda Insight hahahaha

but I do see what you are talking about.. from a physics point of view..

SCRAPPY
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Old 05-16-2000, 04:14 PM   #25
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COZ,
You are right about completely burning fuel, complete combustion is good combustion. But a an inefficient 400CI V-8 puts out much more power than a 1.8Liter efficient 4.

Good, tunable carbs like Webers allow you tune to very close to perfect combustion for a fairly broad RPM range. Carbs have many circuits an Idle circuit for Idling and cruising, transition circuit for part throttle, sometimes multiple transition circuits (main circuit) and of course it can dump raw fuel down the barrel at WOT to prevent detonation(extre enrichment circuit).
All these circuits as well as maximum airflow and part throttle charge velocity can be tuned with Webers.
The emissions stuff came hand in hand with crappy gas, cars were compromised to make due with low octane unleaded. Overnight in 1972-73 compression ratios went from 10/1 to 7.5/1 Ignition timing was cut, smog pumps and thermal reactors were added and cars were strangled with restrictive exhausts. All this stuff killed performance. It has taken 30 years to get it back. Could you imagine how great cars would be today if engineers weren't distracted by the EPA. We are only now getting compression ratios back to where they were in 1970.


Tim

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