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Discussion Starter #1
Im putting this in the v8 forum because you guys probably know the most about cutouts. Will running through cutouts hurt your engine? How about when the plate is on and your running through mufflers, will it affect your performance by putting a "kink" in your pipes? Id love to cruise around town open pipes once in awhile but I dont want to wear out my engine. Should I get one?
 

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I havent researched it in while but when i did years back there was a big controversy as to if cutouts would even give you more power if your running below a XXX number horsepower. The back pressure that mufflers cause sometimes gives you more horsepower than straight pipes would.

As for the kink in the pipes hurting the airflow, i work for HVAC company and in duct work, caps in the duct can cuase little turbulance at that point and affect airflow a tad. But if you can relate that to exhaust on a car im not sure.

If your doing it just to sound cool i havent heard much on it actually hurting engines.
 

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on a stock engine at mid to high rpms you will only burn exhaust valves..... some back pressure gives you torque and you loose that with cut outs on a normal engine. at the speed the exhaust is coming out of the engine its ALL turbulent and doesn't really matter.
if this is a stock engine my suggestion is 2-2.5max to the cat or muffler and how ever big you want from there..... if this is for a vehicle that you drag but is primarily a stock engine (heads, bore, compr) my suggestion would be to make the cat come off real easily and replace it with a pipe at the track... you should have MORE than enough flow without hurting your engine

Ide hate to live in your town.....
 

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Discussion Starter #4
Well the engine will be moderately modified: cam, heads, compression, intake man, 4 bbl, headers, etc. I was just gonna get them for the sound, not really for performance. Just need to know if Im gonna burn up the valves, or whatever...
 

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moderatly built isn't gonna be built enough.. however if you dont rev the engine and dont do it all the time you will be fine. 3000 rpms or more and you might start to burn them ...... so yes if you just cruise around town once a week with them you might not hurt the engine but the I wouldn't go cruising down the highway....

i dont know how you like the sound, i personally would rather have a quiet 350 than a noisy 4.3........ my preferences lean towards sleepers.... just opinion though
 

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Discussion Starter #6
What's the difference in running open pipes on a heavy modified engine and a mildly modified? Why would it be hard on one and not the other? Dayum, whats the fun of runnin open pipes if you cant rev it up?
 

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whats this going in, a 92? gonna keep it carbed or FI? if you go carbed you should jet it with open headers or else when you pull the caps off you will go lean and burn valves. If you keep it FI move the 02 sensor befor the cuttouts and you MIGHT be alright, then again it might run like crap because the A/F mixture might go crazy. Put the 02 sensor a fair distance from the cutout too, this will minimize any false readings.... if you eliminate the 02 sensor with one of those things that fool the computer you will basically have a carbed engine and be stuck with one a/f mixture and probably burn some valves. To build a motor that will surly not burn valves it has to be a fire breather....... late models-sprints-stock cars-dragsters dont burn valves because they are jetted for the 14:1 a/f ration at peak hp rpm and are ussually still have back pressure due to the displacement and compression however small back pressure. Thats why it is common for these engines to load up if idled for any prolonged period... they arn't made for it... as most street engines arn't made for open headers

so if you can keep the engine at the proper burn then you will be alright

yes you can run open headers and never have a problem, but there is always the risk. I had a friend burn his valves on his 350 because he ran 3" dual exhuast with 3" packs......

most people with street rods who drag only pull the cut outs for the track. Why? they like their engines and dont care for the noise

im gonna get flamed for this
 

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Discussion Starter #9
Heres the setup:
'99 4.3l shortblock
270hr cam, roller lifters
vortec heads(port, polish, gasket match, valve job, decked to 10:1 compression, etc.)
edelbrock intake manifold
headers, 600cfm holley carb, 2" spacer
true roller timing, underdrive crank pulley
msd probillet distributor, 6a box, blaster coil
stock ypipe to 2.5" pipes to flomaster 40, no cats.

I think it would be fun to have the option to open up the pipes every now and then, its not something I would do often, I couldnt stand the noise. For racing and offroad, I would definitely run the full exhaust. But if theres a chance that I could burn up this perfectly good engine, I won't even consider it. How much does the mixture need to be richened to run open pipes? I dont want to rejet everytime I go wide open.
 

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where are you putting the cutouts in at? one after the y pipe or are you putting them in each side of the y pipe?

if your going with one at the end of the y pipe i would say you will be alright.. heck, there are going to be alot to say you will be alright no matter what you do.

im going to leave it with... check the plug color after one night of runnin open and if it isn't dead white you should be alright...

all that work into a v6..... im all for a v6 but it would be alot cooler with a sbc and all that work done
 

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Discussion Starter #11
It would be easier to put just one behind the ypipe, I'll probably just do that when I scrap the cat. Id think with a cutout AFTER the y-pipe, there will be enough backpressure. I know what you mean about a v8, but im shootin for 300+ hp which is good for a v6.
 

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Discussion Starter #12
Hey this is off-topic, but with the setup I got, what temp. thermostat would work the best? Stock 195 or something like 180? I have stock cooling system and no a/c. Thanks
 

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since your going carbed you can really put whatever you want in...... 160 would be fine..... 180 would be plenty good too.... i wouldn't go with a 195 there is no need for it on a carbed engine that doesn't have to worry about emissions. Being brand new I would go with a 180... on older worn engines i prefer to run a 160
 
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