SnoBall wrote:
Ive talked to a few people about this, both experts and others, they all are apposed to what you guys are saying, they seem to believe that the only people they know with them are purists and people doing resto's. there arent a lot of people who can tune twins well, and i dont know many either. The cost of rebuilding them seems a bit scarey too......
Quote:
they will use the same amount of fuel, up until the point where they make more power than the other..
i'll dissagree there, it comes down to which units are tuned best and are the most effecient. why can a single throttle SR20DET out-perform a quad throttle SR20DET set up? its all in the development.
If anyone has done such a swap, let me know cheers! (The SU's i mean!)
I'm going to quote a bit of Vizard here...:
David Vizard wrote:
I would like to bring one point to light: Many people are under the mistaken appregension that twin carbs will use more fuel than a single carb...This is a complete and utter fallacy.
Remember a certain amount of fuel has to mix with a certain amount of air. Within very close limits a set quantity of air is needed to produce a given horsepower. Because fuel/air ratio is virtually fixed, this means a set amount of fuel is needed to make that horsepower to go with the air..
The net result: For a given HP, if all else is equal, the twin-carburetor setup will use no more or less fuel than the single-carb setup...
Which is what I was saying..then he goes on in further detail which i can't be bothered typing or explaining...
Also says and i quote:
David Vizard wrote:
Twin SU's feed straight into their respective ports; therefore the mixture distribution is better. So for a given horsepower, you actually use lessfuel.
David Vizard wrote:
While I am on the subject of arguements against twin carbs, let's look at another one. A lot of people go for the single carb because it's easier to set up, and there are no balancing problems. Many people are afraid of the twin-carb setup because they are not sufficiently knowledgable to be aboe to set the carburetion correctly. They also argue the carburetors "go off tune" too easily - quicker than the single ones. The first arguement won't apply cause somewhere in this chapter I'll tell you how to performance tune SU's, so you'll know how to do it. The second arguement is just one of those old wive's tales. Twin SU's do not "go off tune", unless you have a loose screw somewhere and it physically moves. What happens is the rest of the engion starts to carbon up, wear out; plugs are getting on their last legs, ignition tails off, etc., etc., and the performance of the car deteriorates....
and it goes on..
Buy the book.
Haha Chris..SR20DET is a 2L Nissan motor...and i'm not got to bother discussing it..
