Today i was looking at a nice set of electronic cut outs to go with my exhaust..would i or anyone else actually gain HP from them? no point in throwing my money away if i wont gain anything besides noise..if i i'd see a bit of a gain ill go for them for sure. Or is it more for the people making 700+ i'll be using a modified set of shorty headers & 2.5" down to the cut outs..the cut outs would start about 6" further back of where a usual set of long tube's would end.
sure they will! you must keep in mind that ANY additional length of pipe after about 12-24 inches behind the collector(often called "collector extensions") will cause power losses in most cases as it changes the resonant tuning and backpressures. Also imagine that bends reduce flow and add to that the fact that mufflers themselves compound the issues even further and it's easy to see why cut-outs can be so effective. I have used the old fashioned manual style cable actuated style a few times through the years and have several friends running the electrics in street/strip cars with great results. They're most effective on higher rpm(high exhaust flow) setups.. but even bone stock motors will realize gains from reduced pumping losses. I even had a manual set on my work van for all of about 9 months(they leaked too much and I eventually took them off). The power gain was quite obvious as you opened them up at steady state throttle/cruising down the highway because the van would speed up slightly(about 2-3 mph) without changing the throttle angle. Almost like the way an AC compressor slows you down slightly when it kicks in.. but just the opposite. Just keep in mind that the cops WILL hear you from a mile away and be on the lookout as you drive by. I wouldn't recommend doing many burnouts and/or racing around town with them opened up. Don't ask me how I know that. lol
Yes you will, but how much??????????????? And it really depends on the motor......................one of my neighbors put a pair of QTP's on his 2011 Camaro...........strapped to a chassis dyno pulled almost 20HP difference when they were open vs. with them closed............but it was all above 5000rpm. Below that it was a gain of only 2/3HP. Now, how much are you going to spend on the electric cutouts?...................I know the QTP's set my neighbor back (with installation) almost $600.00..............................an N02 setup will gain three times the HP and cost about the same amount of money........IMHO? I had cutouts on my 52 Chevy w/Corvette 235ci 6...................and that was almost 50 years ago............but with the choke on the tripower it almost sounded like a V8.................almost.
I ran Mr. Gasket cable operated cutouts on my Comet from mid 2007 to late this year. I learned a couple things along the way.. -I ended up using some safety wire to keep them "open" at the beginning of 2008 and on because they rattled like crazy when closed. -They are LOUD and sounded badass when I first got them. As time went on, I developed an issue where my body created an excess of ear wax to protect my eardrums from the noise and had to have my ears flushed every year. -I never could get rid of this flat spot my car developed from about 2500-3500 with the cutouts open. After I redid the exhaust (2.5" piping, "Flowmaster" knockoffs dumping in behind the axle) the car felt quite a bit more responsive and the flat spot was gone. This may have also been due to the fact that the previous exhaust system was poorly made. It went like so- Collectors, cutouts welded to the 2.5" reducers. After the cutouts there was an 8" section of 2" pipe then finally back to 2.25" to the mufflers. -Now that I think about it, could also be that I have an internally stock 302 as far as I know, just bolt-ons, the only time I pulled the pan was to change to the oil pump and pan gasket. -If you have stuck up neighbors (my neighborhood is composed primarily "upper-middle class" families with 2 European or Japanese "luxury" cars) prepare to get tons of dirty looks. -I don't have experience with electric ones though, which I hear are FAR superior to what I had. Hope this helps!
I've already purchased a No2 set-up as well..maybe i don't need the electronic ones..how good of a seal would the wing nut style or the bolt on cap would make/how long would they last..because they are a lot cheaper. this motor i got now i should shift at 7ish..so at higher rpm i would probably gain hp as well? 20hp is a lot of "free" hp to gain. As well as running them open all the time it wouldn't happen...would only happen at events and races, so the loudness isn't an issue. - especially street racing...around here that gets your car impounded & crushed or sold at auction due to a law being passed in like 2008ish (yet they wont make a legit 1/4 mile track)
I have had cutouts on mine for over 15 years now! I use soft alum gaskets and mine are quiet. I run 11.50's with them closed and 11.20's with them open...and have 2.5" pipes(although my pipes arn't so good bend wise) with flowmasters...so it can make a difference especially with proper jetting
In your case(no illegal intentions).. it sounds like a well designed system with capped cutouts should work just fine for you and save you cash in the long run. A buddy of mine has a nice system which I helped him design/build and has a removable rear section(including mufflers) just for strip duty. Not only does he get the high-rpm power boost.. but also drops weight in the process as well. That's the same type of modular system I will be implementing into my cars exhaust layout as well, only mine will have electric cutouts since the car will have a dual personality. Just need to make sure your class rules allow rear section/muffler removal.. and that you have a safe spot to store them during your runs, is all.
Any gain will depend on how restrictive the rest of your exhaust system is. If you have 3" with mandrel bends and straight through mufflers you will not see as much gain as if you have 2.25" with crimped bends and more restrictive mufflers. Also keep in mind your carburetor jetting will be different if you have them open or closed so to get the MOST gain you will need to tune for it. They're mostly for fun though!
it just...sounds faster... kinda like the...fart box Honda...sound... as stated...if you have a balanced exhaust system for your engine to start with...no gain.
If you have room, install termination boxes after the header collectors. Makes the headers think they are open to the atmosphere but the exhaust stays quiet.
If you have a mild 302 with a decent twin exhaust you won't notice a difference. The only car I have cutouts on is my 02 Camaro. The exhaust goes into a y pipe and I have a cutout. I have only made one nitrous pass with the cutout closed and it went a 7.29 at 95 spinning. With it open it went a 7.18 with a much better 60ft. Honestly to me they are not worth it unless you want to make noise
all I can say is that you guys must have some really badass exhausts on you cars if you can't tell much difference between an open exhaust coming right off the header compared to pushing spent gas all the way out over the axle. No motor ever likes to have to push exhaust that far. Or for that matter.. even half that far. I say this because.. ALL.. the serious street racers I know who actually drive their cars to a race(rather than pulling off a trailer to "run-n-done").. use them and they pick up far more than a tenth or two. And two that I can think of have 3.5 inch exhausts for sure and another supercharged big-block chevelle is running a sewer sized 4 incher. And these are all canned and dumped systems that stop far short of the axle too.
i consider my car to be a fair bit more than a "mild" 302...it will need to breathe when its at 7000rpm...maybe more. after thinking about this and reading a fair bit of responses here and old topic on other forums i do believe i will gain from this...and well if i don't i wont be out much as the "bolt on/wing nut cut outs are less then 100 bucks...so for less then 100 bucks it's a risk im willing to take...maybe or maybe not picking up .3 on the track seems worth it & beats the hell out of not doing it and having to unbolt half my exhaust system.
Dude!.. if ANY exhaust cutout.. even a sharply transitioned one with haggled up welds slagging into the pipes interior.. doesn't immediately increase your throttle response and make AT LEAST another 15 horses at 7,000rpm compared to a full exhaust system?(ESPECIALLY one with chambered mufflers because there's usually 5 horsepower lost in EACH muffler alone).. you seriously need to find another tuner to help you out with these sorts of things. No disrespect intended to anyone here(yourself included).. but anyone worth their engine building/tuning salt who's ever run a car with open headers.. then added extensions/turn-downs(at this point.. properly tuned lengths can actually increase power levels).. then added half-backs with mufflers.. then added over-axles.. will kindly tell you what each and every extra bit of exhaust pipe will do to power levels of an engine in negative fashion. And sometimes it doesn't even have anything to do with absolute flow itself either. It has more to do with the complicated matter of pulse wave/resonant tuning and its affect on the intake system itself. Even cutouts can.. and do.. cause flow/power losses over properly tuned collector extensions alone.. but it's sure as hell a far better design than zig-zagging or squishing through mufflers and pushing those gasses out a full length exhaust system. I know it sounds harsh.. but anyone who can't hear and feel the difference isn't tuning properly(carb OR efi). In fact.. you almost ALWAYS need to(unless the tune is already so far off that it "comes back in" after the exhaust mods) retune an engines ignition and fuel curve when adding a full exhaust as compared to the tune required for open headers. Hell.. I've helped guys retune after doing a simple collector extension alone! That point alone tells you what's up with how an exhaust.. or lack of one.. affects an engines tuning requirement and overall power band. The way I really see many of these discussions in the end is this. There really aren't as many 1%'ers in this world as you'd imagine and some are just fine with the accepted mainstream gains.. or losses. Those who want more keep working for it. Nuff said.
