i just got my cutout, but everybody tells me not to install it because it will melt my valves. i'm hoping that's not the case. i wanna install it before the cat, so it will be fairly close to the exhaust manifolds (if that makes a difference). i don't care about performance with it (all i have is a 305 so performance isn't an option) all i want is sound, but not at the expense of screwing up my motor. so, is this true that it can hurt the engine?

by the way, i couldn't find anything thru a search, but if there has been a post about it i'd appreciate a link.

 

nope, pure bs

 

who ever told you that is a :lala: . go to any exhaust shop, and have them replace your cat with the cutout. it will sound loud and you can cap it easily. i ran it like this on my old z28 for a while.

 

If you just want "loudness" or as an obnoxious a sound you can muster, just get straight pipes from the catalitic converter and forth. An SLP loudmouth cat-back sans the resonator should terrify all those you keep close(not just your family who's in the house but people who live CLOSE)
The reason I say "cat-back" is if for some reason you have comply to inspection/emissions check, you should still be the most noise polluting donkey's rear section excretion unit on your block and still be sorta legal.
The last thing you should worry about is burning your valves...after all you don't care about performance. LOL.

 

are you trying to say that there aren't any performance benefits from cutouts?

 

newbie takes a stab.

Having cut outs (when open) is in essence opening your headers, which relieved a lot of back pressure on your engine. Cutouts wont give you a 100hp boost or anything, but it will help a little bit performance wise. And even if it is noticable, your engine will still appreciate being able to exhale every once and a while.

------------------------


I have heard you have burn up valves too... and even crack an entire block if you engine happens to suck up a jet of cold air into the hot engine on a downshift.

So that is complete BS?

 

the only way you can "burn a valve" with exhaust mods is if you run your engine with no exhaust manifolds or headers.

 

i went as far as running new headers and just the y-pipe, i ran like that for 4 weeks, then got my catback on. my car still runs good and no burnt up valves as far as i can tell.

 

where did that stupid idea ever come from anyways?? and to think of it, i've heard of burning a valve, but not melting it.

 

melt the valves???

sorry but that made me laugh fairly well

the person who told you that has no clue about what he is talking about


as mr_dude said the only time you would worry about burning/craking/warping a valve or whatever is with NO EXHUAST... that means headers/manifolds (whichever you have off as well)
and even then not sure what the chances are


but with less backpressure in the exhuast you reduce the resistance to to the exhuast making the exhuast move faster which would get that hot exhuast gas away from the vavles keeping them cooler




also hot air makes more pressure which would keep the colder air out of your exhuast system, and then if any air does go up the exhuast it should get heated fairly well by the exhuast itself

so no worries there

 

thanks, i feel better now, because i was gonna install the cutout anyways. now i have less to worry about (can't afford a new motor ).

here's another question: a lot of folks i've heard with no exhaust (straight pipes or cutouts) have backfires. is that bad for the motor, or a sign of something bad going on in the motor?

 

that is fairly common

if you don't like it though never buy a rotary motor
add a free flowing exhuast and you would spit some nasty *** flames




but best I can as to why it does that is with a stock exhuast setup the there is enough resistance in there to cause the fuel to burn in the exhuast (exhuast moves slower through stock exhuast) and also with an aftermarket exhuast you are prolly getting a little pull through of fresh/air fuel which is burning in the exhuast ( better scavenging)

niether one of those are going to hurt performance or anything else




but if you are not backfiring with the aftermarket stuff then start to out of the blue one day.... that might be something to worry about

 

Umm... the exhaust would have to be over 5000* to melt steel valves

 

yeah..thats definently BS....I was told maybe if you didn't have any manifolds/headers on your car...it might..but not with a cut-out. I've had mine on for like a year now...and it's great..I absolutley love it....I have the loudest 3rd gen around here in the area.....and it's REALLY fun with the Electonic McCord Power Plate II

 

Why should anyone take advise from someone who doesnt have a single valve in there engine? hehehe

that person that told you that... kick them in the nhut sack for me please... Maybe all thoes pro streeters and drag racers that run open headers go through thousands of valves a day... THATS why they are always rebuilding the engines after a race...

 

umm no. They rebuild their engines after a race because they have close to 7,000 hp and everything in the engine is severly abused to they have to tear it down every run to make sure it didnt hurt anything. It has nothing to do with the valves. rx7 was right. Melting a valve or hurting a valve in someway by using a cutout is crap. Ever wonder why a top fuel or funny car uses such heavy oil? It's because in the course of just one run from the start to the finsih of the race the clearances in the engine are so big too free up lost hp due to friction that the oil breaks down in just 1 run. That is why they rebuild the engines every race. it has nothing to do with melting the valves. That is just some old wives tale and it is absolutely not true.

 

After every run, the top fuel drag motors are torn apart and they inspect the exhaust valves and change them if they look burnt.
They also change out thier clutch discs as well. There is a 20 minute limit to the work that can be done on the drag car.
This was in an NHRA or IHRA article I read on the net a few months ago.

Also, you can burn valves when running headers, probably more likely with shorties than longtubes. I believe it happens when cold air is drawn up the header(s) when the car is running.

 

I have nothing but good things comming out of my cutout. Ive had it on for about a month now and cars still running strong. My friends tell me it's to loud but i dont beleave it.

 

can you explain how cold air would burn something?


also how could air even get up in there with how fast gas leaves the cylinder?

 

it doesnt "burn" them.. thats mostly a expression. but think of the temp diff and its effects on metal.


as for the popping, you car does that anyway.... but by changing the exhaust you can hear it..... most exausts tune that sound out, while others make them louder.....

 

Cold air isn't drawn up into the valves. Thats the thing. When you shut the engine off air doesnt miraculously rush up the headers and onto the valves. How many people on here run cutouts or open headers and how many have actually "burnt" a valve? I have heard all the old tales about this happening, but not one single person who actually had it happen. You know why? Because it's simply not true. It was probably started by some drag racing or dirt track guys so that their competition wouldn't run open headers and then they would have an advantage. This whole myth is simply not true. Cold air just doesnt misteriously get sucked up into the heads and "burn" valves. Just doesnt happen. Atleast not to the probably thousands of people who run open headers or cutouts that I have seen. Think about it, take a pan and put it on the stove and heat it up to the highest setting it can get to then turn it off and take the pan off the burner all at once and let it air cool. It won't have any adverse effects. The only way you would harm something is if you took it directly from the stove to cold water. Otherwise everything will be fine. The same thing applies to valves.

 

i agree with the above...... as long as you have headers or manifolds, you wont harm your valves.


but you can harm them if you dont have any form of exhaust on them (ie, open ports and thats it)

 

I love my cut-outs. You can't go wrong with getting cut-outs there sweet. Other than I just got a ticket for it, but the cops dont know that i was running with the cut-outs open. Just watch out for the cops and it'll be all good.
Peace Out,
PsychoGTA

 

thats why i want to get a power plate..


get a nice, quiet exhaust... perfect for crusin with the top down around with... and for daily driving

and drive around with it open when i want to cause a lil trouble


and if i ever do get stopped by a cop for the loud exhaust, you can bet that plate will be closed before he even gets out of his car...

uhhh revving officer? as you can hear, my car is pretty quiet.... that damn mustang though, he was making all kinds of noise....

 

ummm i was being very sarcastic... i was laying it pretty thick...

 

eh I think 25th just has too much ls1 on the brain

if he would lay off the stuff maybe it wouldn't be so bad

 

i just welded in this cutout (only took me 3 weeks to get around to it ) and it sounds soooooooooooooooo good. i just hope i don't get a ticket. oh well, it'll be worth it.

i put it after the cat so it wouldn't be as loud, and somebody told me the cat would help muffle it and make the sound deeper and prevent backfires. don't know if it's true or not, but i'm damn happy with the sound. now if only my car was fast

 

werd to yo mothua! it is one of the sweetest sounds one man can hear. I cant wait to put headers on so i can hear it again!! maybe ill put a cut out between the y pipe and the cat....hum :lightbulb:

Yeah, the cat will muffle it alright... but not deeper or backfires. I noticed a LARGE difference when i had a cat on and a cat off. I probably could run no muffler and just run the cat and it might of sounded pretty dam nice... oh well.

 

Burning valves is not a myth. It's totally possible, but not why people think.

Sometimes the answer is SO obviously right under your nose, you can't see it.

It's called running lean.

When most people install headers or open up the exhaust, they fail to tune (be it re-jet the carb or burn a new chip). The result is burnt valves.

The exhaust valve is normally the one that becomes damaged because it never has cooler air flowing over it like the intake valve. It always has hot air running over it. If the "cold air rushing into the exhaust will burn a valve" was true, then we'd burn intake valves everytime we drive our cars.

Another common thing among racers is to run rich. It's not as efficient, but it's safer. The unburnt fuel helps to cool the valves.

It's the same thing with gaskets. Ever seen a header glow red? It's because the engine is running lean, and that in turn can burn out the gaskets.

I've had multiple cars with headers and only ONCE did I have a problem, and it was a gasket. It was a Holley carb on a DP manifold. The guy I bought the car from didn't install a fuel filter. The pass side primary jet got clogged and caused the #1 and #7 to burn the header gasket.

Plus, I've spent A LOT of time around circle track guys who ALWAYS test an engine (before installing it into the car) without any exhaust. NONE of them burnt a valve from doing so.

So yea.... burning a valve because of cool air is a myth. It's actually caused from running lean.

 

Ask TunedPort335 what he thinks about his cut-out.

He gained 20RWHP & 8 RWTQ from a $35 dollar part.