Re: 220hp? [All this carb crap]

[16V Jason <jason@scirocco.org>]

Okay, I've just about had it with this "Carbs" bullshit, and I'm going to 
throw out a few questions and maybe someone will tell me why this 
prehistoric notion of fuel delivery is making its way into people's minds 
as a viable way of making more horsepower.

While it could well be that Andy King's carbed Mk2 Golf gets 233, but when 
you say something in the next sentence like "And [only] 212 on the K-basic 
equipped Golfs", that gives people the impression that carbs somehow give 
you more horsepower.

Okay, let's talk about this, folks.  Yanking the intake manifold and all 
fuel-injection system stuff off of your 16V and replacing it with carbs -- 
1 of them, 4 of them, or 27 of them, will almost definitely NOT give your 
car any more power.  Why?

A look back at the ol' physics book will tell you that the most complete 
combustion (and therefore the best power) will occur at _slightly_ richer 
than stoich (14.7:1) mixture.  Therefore, your engine will put out the best 
power if you have a fuel delivery system that meters the fuel as precisely 
as possible from idle to redline and at any given throttle position, 
keeping the mixture almost exactly at stoich.

Guess what?  There's a good reason why carbs were eliminated on production 
cars.  The reason is because (in addition to the horrible starting and 
cold-running crap they're famous for) they are horrible at metering fuel 
precisely.  If they weren't, a carbed car would (a) pass emissions testing, 
and (b) make more power than its fuel-injected equivalent.

Well, we know that both (a) and (b) are false.  If (a) weren't, most of the 
cars on the road would have carbureted engines just like their Euro-market 
counterparts did up until Emissions Regulations stepped into effect 
there.  And if you look at the power output of any carbureted engine versus 
its fuel-injected counterpart, the FI engine will make more power 
REGARDLESS of how prehistoric and simple the fuel injection system.  It'll 
also be much emissions-friendlier and get better gas mileage.

To see these in action, take a look at any 1980s car line in 
Europe.  Looking in the back of the owner's manual on my Euro-spec 190E, I 
see that the fuel-injected 2.0 8V in my car puts out 122hp, whereas its 
carbureted counterpart (same exact engine, no fuel injection) makes 90hp.

The reason that people put carburetors back in cars originally designed for 
fuel-injection is for the purposes of FLOW.  If you have an engine that 
flows so well that it maxes out the capabilities of your fuel injection 
system -- or  your intake system becomes restrictive -- then you'll benefit 
from anything that will allow the engine to suck in more air.

However -- make no mistake.  If you were able to put a fuel injection 
system on the car that flowed as well as the 4 individual carbs do (by no 
means an impossibility), you'd be making much more power.

So, the original question was -- is 220hp possible from a 
normally-aspirated Volkswagen 16V?  Well, in short, yes, anything is 
possible.  Would it be worth it?  Absolutely not.  Would the car be 
drivable on the street?  Forget about it.  To get 110hp per liter from a 
normally aspirated VW 2.0 16V is about as likely as getting 100lb-ft of 
torque per liter out of a Honda engine.  Honda and BMW can produce engines 
with that kind of specific power, but there are many differences.  First 
and foremost, they have an almost 20-year advantage in technology compared 
to the VW 16V, which was, remember, one of the first multivalve engines on 
the market.  Secondly, and perhaps more important, they use a sophisticated 
engine management that, in one computer, has complete control over ignition 
timing, fuel injection timing (and quantity), and valve timing.  CIS-E (and 
Motronic) aren't even in the same league.  And third, also very important, 
they're very short-stroke motors.  The 16V isn't.

Think about the 1.8T for a minute.  You have a 1.8 liter with 5 valves per 
cylinder, a sophistocated engine management system, new technology, etc, 
and a TURBOCHARGER and from the factory it generates 150, 170, or 
180hp.  (i.e. < or = 100hp/liter).  It takes bigger turbos, intercoolers, 
and modifications to the pistons, rods, crank, and valves to get it to 
220hp reliably, which is 120hp/liter.

That's because, like most VW engine designs, it's not a severely 
undersquare design.  So to get it to rev fast enough to produce that kind 
of specific power (8500+ rpm) isn't going to be pretty -- or, more 
accurately, possible.

My $3.24
Jason




At 03:20 PM 11/13/2001, UrGTI@aol.com wrote:
>Andy King is selling his SCCA legal MK2 golf with 233 hp which was built by
>Bertils.
>And that is with carbs not modern FI.
>Tim Stiles of TSR in the UK has told me he gets 212 on the K basic equipped
>golfs since the rules in the class he builds for requires stock external
>components.
>
>As far as just tossing on some Tbodies and getting 220 we all should know its
>not that easy. Making that kind of power will require plenty of dyno time
>with an experienced tuner at the keyboard of that laptop programming the ECU.
>Of course the rest of the engine must be optimized also, balanced and
>blueprinted, P&P head, healthy cams, good exhaust.
>
>Jasin
>happy wrenchin'
>
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