So i'm spending the winter fixing up my rex, rebuilding whatever I can, getting it painted, replacing some interior parts next year. What i'd like to achieve for it next year is to have a perfectly usable daily driver, something that will pass emissions, not be to loud, and get decent gas mileage. On the other hand, I want it to be fast, loud as ****, and get as low of mpg as possible. So I came up with some idea's to go about having this, and i'm thinking they've already been thought of, so I just thought i'd check.

#1. Have racing beat header, and then beyond the header it splits off into two exhausts. One is a stock exhaust, and the other being a straight pipe. You could control which one is being used by a switch in the car.

#2. Have another switch in the car controlling the carbs. Flip it down, the carbs are running at stock settings, flip it up, carbs are running as rich as they can for best hp.

Anyone ever try either of these? I'm not a mechanic or anything, so i'm not sure what the great difficulties would be in either of these systems. And any other idea's for things you could flip on and off for max performance vs best daily driving conditions.

 

Well, they do make exhaust cut out pipes that are a butterfly valve that goes in the exhaust, so you could do that, but theres no point in the RB muffler and stock exhaust after that. The stock muffler is a giant cork. Just put full RB exhaust on it, get great power and stock sound 80% of the time.

Well, first of all, running rich as hell wouldnt make power, running leaner makes power, thats why turbo engines have so much monitoring the mixture. You want it to run as lean as possible without damaging anything and still making power. Running too lean causes power losses also. My advise for this would be to just get a Weber or maybe a modded Nikki. I cant speak for a Holley, I never used one. My Weber DCOE got the same gas mileage as my stock Nikki if I drove it normally. Romp on it and it would suck it down.

~T.J.

 

#2 would be damn near impossible unless you have a "controlled" vacuum leak in the mani, not even sure how well that woud work. iwould just try to find a happy medium

 

#1 it would be better just to put an rb header on with a nice high flow cat and rb muffler.

#2 would be also easier if it was FI.

#3 just add nos.

 

A bunch couple of solinoids, a y branch with an electrically controlld damper and a 12 Volt PLC and the both can be done.

It would not be easy but it could be done.

The exhaust one could be done easally with a mechanical solution ie have an Y pipe off the headder with a damper in it that is switched form Street to race via a handel that goes up through the flour. That leaves all the motors and stuff out of the equation...

I don't know enough about Carbs to say on the other one but you deffinatly need some sort of PLC (automation computer) and some sort of electrically actuated device to cahnge the carb settings.

Pritty tuff but not impossible (the best I can tell, I don't know weather the carb will allow yo to do it or not, you may end up having to modify it quite a bit), mind you any thing is possible if you have enough money...

I work in automation this is the sort of stuff I have to find solutions for every day...

EFI we don't need no stinkin' EFI

Carbs are your friend they add persoality to your car...

 

its called watching your RPMs

the more you rev it up the more power your get/ less fuel economy / the louder it get
the more you keep it in the low RPMs the it is more quiet, better fuel economy, and more dependable. With in reason.

 

as far as cleanlyness, use propane. Your car will run forever.

 

This is all sort of a budget solution, haha. I was just thinking it would be quite a bit cheaper to lay down a seperate straight pipe exhaust rather then spend the big bucks on a new rb exhaust. As well, straight pipes are so loud, could be fun for temporary usage

 

Ok. It is possible to electronicly control a holley 4 barrel, but it ain't cheap. If you really want to do it, call holley and ask where you can buy an electronic metering block. It uses a controller on the dashboard to control the size of your primary jets. I have only seen one in a book, but I know they exist.

You are right, BTW, normally you go richer to increase HP, but only up to a point. Right around 13.5 to 1 is the air/fuel ratio for max HP naturally aspirated. You jet leaner for economy. Lean max power is 14.2 to 1. stoic is 14.7 to 1.

But, if you burn more fuel, you have to make sure you get enough air in, and the exhaust out. Hence your better exhaust.

You can build you exhaust up with a RB header and presilencer. But, put a butterfly cutout after the presilencer, with one end routed to your normal exhaust, and the other to a straightpipe that runs right out to the side of the car.
You can buy on from summit racing, but some fabbing will be required, and the open exhaust should never be used on the street, or without earplugs!

 

If you want cheap flip switch HP, get Nitrous!

 

wait i got it!you could just tool around on the primaries and like someone else said have a solenoid for the vacuum advance like an inline block so that your secondaries don't open till you open the circuit allow vacuum secs to function normally.

Edit: damn nevermind the vacuum secondaries pod thingy attaches right to the carb....hook your choke cable up to the secondaries?? i dunno

 

There are electronic versions of these now. Not sure how long a mechanical or electrical one will last in the heat produced by the rotary exhaust.