Tuned collectors on a car with exhaust? please elaborate

 

hurst posted links that explain everything on the tuneable collectors

 

Tommy is like Joe,.. neither of them like to read more than 2 or 3 lines at the most and they have selective comprehension. At least Tommy does for sure.



Hurst

 

lol

 

you cannot forget one thing

these so called technical articles are not always true. so to throw a bunch of b.s. around just to make a point is like giving false info ....believe all you can see and half of what you read or copy and paste.....

you cannot sell a product if you have no info...most of the junk you read is like believing in the tooth fairy......

 

1: If you don't have mufflers on the car, get some. It may not make more power but, it will improve drivablity and at least give the illusion of more power.
2:Why is your fuel pressure so high?

 

Did you even read the links I posted John? Neither article is selling anything or supporting any name brand. They are just tech and explaining methodology.

Just because the tooth fairy never left you anything doesnt mean you should ruin it for others.

Hurst

 

Exhaust backpressure the myth - ThumperTalk



- It's about velocity (like a couple others said). You want as little backpressure as possible while maintaining the appropriate velocity to compliment your desired powerband. A large exhaust volume (such as a race engine screaming at 8-9k) automatically creates a high velocity, so people use open headers to improve their peak numbers in those higher RPMs. Is the velocity killed in the lower RPMs, where a street car would normally operate? -yes. Do they care? -no.

-You see all the time where just adding longtubes decreases low RPM torque but vastly increases top end HP. It's all a give and take. A great example in the article above is how Ferrari uses dual exhaust paths to promote higher velocity at lower RPM but less backpressure at high RPM. Vettes and other cars are starting to do this as well.

Everywhere you look, manufacturers are using technology to improve/modify flow velocity of their air pumps (engines). I first noticed this in the FR500 magnesium intake that had butterflys that opened and closed at specific RPMS - optimizing air velocity entering the engine by mechanically lengthening and shortening the intake runners. The same thing is achieved by variable cam timing (which is showing up in pretty much everything now).

So, to answer your question - put some mufflers on the damn thing - I don't want your 200hp car to blow out my ear drums when it goes by. A reasonable 2.5" exhaust system is fine for most cars out there. Will you extract that extra 5-6 hp? -maybe, maybe not, but trust me, the money is better in your pocket.

 

I tried to stay out of this pissing match but this is the best advice here...

 

Theres a few things in that write up I disagree with. For the most part he's generalizing and it sounds plausible,.. but when you think about it,.. it makes absolutely no sense.

About 20 years ago I read an article written by a GM engineer. He was on the team that designed the TPI intakes. He specifically stated that in order for the engine to run at optimum efficiency, that some back pressure is needed. The induction system was design for it.

The guy in the article is talking about exhaust gas velocity. Once the exhaust passes the manifolds why the hell would it NEED velocity anymore? Using a 4" exhaust would kill power,.. yet open headers will not? Come on. I can see velocity being needed in the induction. Yes.,. I agree 100%. And with a forced induction engine,.. I can understand where velocity is crucial. But I dont see where it plays that big of a deal with an NA engine,.. well at least once its passed the manifolds as long as the exhaust is not restricting anything I dont see where it would lose anything by virtue of lost velocity at the mufflers. It goes against so many other articles written by experienced well known engine builders.

Smokey Yunic wrote a book book on the subject a while back. I dont have it anymore. I'm trying to find it online. You guys cant argue with old Smokey,.. he is a legend.

Hurst