Tubocharger, meets Venturi ???
Tubocharger, meets Venturi ???
(OP)
My goal is to build a High street tired 12'sec car and get somewhere in the nieghborhood of 40 mpg. and don't doubt me the last project was a 86 GLH Dodge Omni. ran 13.4 all day long and averaged 35 mpg. oh yeah and the whole car was put together with junkyard parts for less than 1000 US dollars.
The current project car is a 1985 Shelby Charger running a 2.5 turbo engine.
The ??? I have is why have I never seen a venturi setup on the exhuast side of things. The thought (may be way off base but.....) is to take a "ram air" style duct from the front of the car and run this ducting towards the rear of the car. At some point along this path the exhuast system would "T" into this pipe, so that given enough air volume and speed a suction would be created on the exhuast system.
The problem I am trying to overcome is that a large turbine side A/R is laggy and has some effect on the fuel economy. and using a stock .48 A/R leads to 45+ psi of pressure in the exhuast manifold, in my particular set up. So in theroy if a "large" enough suction could be created I could get by with a smaller turbine A/R and trick it into thinking it was bigger than it is.
??How am I wrong ????
Or how fast would I have to go for this to work :)
The current project car is a 1985 Shelby Charger running a 2.5 turbo engine.
The ??? I have is why have I never seen a venturi setup on the exhuast side of things. The thought (may be way off base but.....) is to take a "ram air" style duct from the front of the car and run this ducting towards the rear of the car. At some point along this path the exhuast system would "T" into this pipe, so that given enough air volume and speed a suction would be created on the exhuast system.
The problem I am trying to overcome is that a large turbine side A/R is laggy and has some effect on the fuel economy. and using a stock .48 A/R leads to 45+ psi of pressure in the exhuast manifold, in my particular set up. So in theroy if a "large" enough suction could be created I could get by with a smaller turbine A/R and trick it into thinking it was bigger than it is.
??How am I wrong ????
Or how fast would I have to go for this to work :)





RE: Tubocharger, meets Venturi ???
Regards
pat
RE: Tubocharger, meets Venturi ???
So if it won't create a 5 hp increase anywhere in my powerband, then what about just cruising down the highway at 70mph. at 2500 rpm with the throttle just barely open there isn't that much air in the exhuast system. I am struggling to figure out if I could create a pull on the exhuast system would it be a benefit to my fuel economy, by removing some of the resitance found between the exhuast valve and end of pipe. (understandin' that some level of resistance still has to be there)
RE: Tubocharger, meets Venturi ???
Good Luck
Steve
RE: Tubocharger, meets Venturi ???
2. There have been a number of devices such as you propose that have been patented. One is US patent 4313523, issued in 1982. You can see this patent by going to the Patent office website --
http://164.195.100.11/netahtml/srchnum.htm
and typing in the patent number.
None of these devices work, for the same reason that "ram-air" doesn't significantly boost intake manifold pressure. At 60 mph, "ram air" will increase manifold pressur by a whole 0.062 psi. If you want to get a 7 psi boost from ram air, you'll need to be cruising at about 600 mph.
RE: Tubocharger, meets Venturi ???
and 45psi exhuast manifold pressure isn't all that extrodinary. my set up is a 2.5 liter SOHC engine with a t3 garret turbo .42 a/r commpressor and .48 a/r turbine. with a little touch up to the wheels. At 20 psi of intake manifold pressure the exhuast pressure gets up there pretty fast. Yes I know that boost level is way at the top of the efficiency level of commpressor map but.. hey it still made the car faster. I have the time slips to prove it.
Corky Bell recomends a 2:1 exhuast to intake manifold pressure in order reduce lag not give up HP.
I was reading 45psi in the exhuast @ around 15-16 psi. in order to make a 2400 lb dodge omni run 13.4 on a slippery track/ with street tires it took 19-20 psi. With more traction that would have been a easy high twelve. My trap speeds were in well past 105mph. Everything that bolted directly to that engine was 100% stock. (head, shortblock,intake and exhuast manifolds, turbo, throttle body ect.)
What got me started on the kick was I was looking at a large truck pipe and got to think'n. I know that there are not to many thing a guy can think of that are new and just going to work outstanding on the internal combustion engine. After all the engineers that have been going after 'em for the last oh 100 years, a good ole boy like me ain't going to just strike gold. but... every little bit counts in a low buck, high performance machine.
I have been lookin' at pic's off GT and indy cars. if I don't see anything there I'll give up this thought.
oh and thanks for the patent #. what do ya know someone beat me to my idea almost to the "T".