truckguy

Running open headers on my auto 5.7l TPI ... Im not looking to build hp, just want to build a custom exhaust ..( just like a straight pipe that fits my truck )


How do I figure out how to design a tube that will maybe optimize performance or at least "satisfy" the engine's needs (how do i determine the size of the tubes)
I dont want to buy headers i just want to building some tubing that extend off my stock ones.

SilverChicken

iTrader: (1)

Size is an easy answer, single 3". You gonna cut and weld your own exhaust go with Summit or Jegs mandrel bent U and J sections, and a few feet of straight 3" measure, measure, cut and weld from front to rear. Don't have the skills or tools then Hooker and Spintech both have 3" systems for around $400. Pretty self explanatory and very easy to do.Actual headers or cast iron manifolds? Shorties or LT's? If you're attempting to do the y-pipe it gets more complicated and a few specific parts are needed. For manifolds or shorties don't go over 2.5" tubing for it until they merge.

What does any of this have to do with destroying an engine?

Ozz1967

iTrader: (4)

Much of the work has already been done for you. No need to design anything. For headers the hooker 2055 or dyno don shorties are 1 5/8 primaries that come with emissions provisions if you wish, a Y PIPE that fits a stock oil pan likens glove and finally, pick your choice of 3" cutback. The single 3" is big enough to handle anything up to 450HP. There is also a picture thread of dual exhaust set ups that way however you have a hard time running that past an auto transmission.

truckguy

no just one pipe from head to the back of the truck.


idk lol is it possible air could get sucked back up into the engine causing incorrect air mixture or other problems like wear on engine parts or internal parts???


also just wondering does a cat make the engine operate better? i mean im pretty sure this car was engineered for a catback , so what is the affect by mean running a straight pipe, or aftermarket heeaders, and what not...?

truckguy

thanks might do this. and i prob wont use headers its too loud, dont need to spend that money, plus my engine prob makes less than 200 hp.

Ozz1967

iTrader: (4)

Get the headers, you will not regret it. I personally had hooker headers but the Dyno Don headers on here have a very good reputation for quality and you can buy them ceramic coated so they'll last probably longer than your car. The up-side is they fit just like stock manifolds except you'll gain roughly 10-25hp (Every car is slightly different). I went with hooker because in 08 Dyno Don hadn't yet made his headers available.

From there get a 3" catback. Just for ease, get a magnaflow set up. They're rather cheap, I found mine for $480 on Amazon.

Outside of swapping cams, intakes and/or heads, this is the number 1 thing to improve engine power/performance.

Also, nothing sounds like a set of headers. Also, the magnaflow isn't loud until you get on it. It's noticeable, but not loud. You can look up how it sounds on youtube.

Dartht33bagger

@Ozz: It sounds like this engine is in his truck so none of this really applies to him. He has a lot more options available than what we have most likely. A few things.

1. A cat is not required but is an emissions device. If you have emissions checks in your state, you will need one. It is also just good to have in general so your exhaust doesn't make the guy driving behind you have to turn off their heater or vent.
2. Headers vs stock manifolds will just make the engine sound a little better and make a little more power.
3. Straight pipes will likely be very loud. I would run at least a mild muffler.

Drew

iTrader: (58)

And this is yet again a non-thirdgen thread on thirdgen.org.

truckguy

1. well thats the thing its a 75 and i live in CA ...so 75 and older you dont need to smog .

2. yeah figured a little more power , what size should i get for the primer for STOCK cfm ?(my plan is to get the motor running closest to stock so im just going to assume the amount of exhaust CFM is going to be stock) what is stock the CFM for a 5.7l TPI 350 btw?

3. that makes sense .. ill look into it. I want to spend as little $$ as possible (not cheap) but save where I can but the get the motor running proper.

truckguy

how is this not a third gen thread ... ? im speaking in terms of a firebird engine where i need advice regarding info specific to the motor ... where else would i get this advice. I cant ask c10 forums about the firebird engine...


to clarify im asking how to build an optimal exhaust system interms of a stock TPI. I want to have a place where I can get ideas for my engine specifically. sorry if that wasnt clear to you.

you expressing your "complaint" in my thread is rather ironic btw ... if you want to speak about necessary / unpleasant posts.

truckguy

na man 400 is too much ...honestly to point out you didnt even specify what size to get .. yet you are saying "you will gain horsepower if you buy these headers" Im not getting headers if i dont need them.

I have headers.. im just asking about exhaust after the headers. "COLLECTION" trying to get an answer with some kind of optimal solution with some exhaust engineering in mind ... I specifically asked to "how to build" because I want to avoid buying things even though they are easier. Not that I cheap but I got time to learn so thats not a problem and I just want to make my own without "destroying" the engine if thats possible..

for example exhaust pipes that are way TOO big affect the engine post - exhaust stroke. But i guess YOURE RIGHT, I shouldn't worry too much about after the headers ...if the primary is the correct size and buying headers a little bigger than the stock would not hurt. still dont want to spend that money tho.

Drew

iTrader: (58)

A SBC is still a SBC regardless if it's got a TPI on top of it or a carb. The requirements of a thirdgen exhaust are more relative to space and packaging. What fits under a truck, and what fits under a thirdgen are pretty distinctly different.

I'm sorry you find it unpleasant, it was intended as a heads up that you're posting off-topic. Generally a moderator would have locked a thread like this by now. It's not intended to offend you, but this is an 82-92 F-body forum.