| Need a catback? - Click HERE for Original Thread |
| testingcheck |
| I was told that if I was going Turbo I would need a bigger exhaust system. I was wondering if I was going all motor do I also need a new exhaust system/catback? |
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| 2ndgenlude |
| it would be a good idea to get the whole thing done to larger diameter. other wise its going to be a bottleneck |
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| testingcheck |
Is it best to get a shop to make me a catback or buy one already made? Do I have to put one of those big mufflers on? Or can I put a different muffler end onto the catback?
Something like this.
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| scooby_dooby |
the turbo would need a slightly bigger exhaust, like 2.5" instead of 2.25 for the typical N/A.
But you don't get much gains at all n/a form exhaust, you get most of your bolt-on gains when you buy an aftermarket header, and that would be a waste if you plan to go turbo. |
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| REFLUX |
For NA applications you want SOME restriction if you wish to retain some midrange power.
A large & very free flowing exhaust will generate most of its hp in the higher rpm ranges, you may even have a loss in hp in the midranges.
As for what kind of muffler, typically you can use whatever you want. Unless you wish to gain every last HP out of your engine from an exhaust mod, I highly doubt the design of an aftermarket muffler will make significant differences.
You can buy premade aftermarket ones or you can make your own.
Look for "mandrel bends" to make up your own exhaust. They are smoothly curved metal tubes that allow for exhaust gases to travel quickly & without turbulence.
If you want something quiet, keep some midrange, get some gains & want to keep it relatively inexpensive, I'd suggest buying a "presilencer", a decent muffler (Magnaflow is a good company) and connect it all together with mandrel bends.
A muffler shop can weld it all together for you but put up a thread in the "Where To Buy" section and ask for a good place to weld exhausts.
Another mod you can look into is a "header".
These are the tubes that initially collect & redirect the exhaust gases straight from your engine.
It is the piece that attaches to the engine and goes from 4 pipes down to 1. It may go 4 to 2 then to 1 as well.
A header usually can not be made by exhaust shops, most people buy aftermarket headers. |
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| testingcheck |
Thanks Reflux for all the info. What size do you think I should go? 2.25" like scooby_dooby says? Also when making an exhaust its not like buying one big piece is it? How do I know what I need? Is the aim of an exhaust to have less bends?
Also I was told that a cat back will give beter mileage true? |
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| TrevorK |
quote:
Originally posted by testingcheck
What size do you think I should go? 2.25" like scooby_dooby says?
2.25" is a good size for a naturally aspirated car making under 200HP.
quote:
Also when making an exhaust its not like buying one big piece is it?
If you go to a muffler shop, they will custom fit the exhaust to your car. Remember, every car looks different underneath, so the pipes have to be routed differently. It will be all one piece when they're done - but it'll be assembled from a bunch of smaller ones...
You can buy an aftermarket exhaust that you can put on in one piece - which is because it is specifically made for one car...
quote:
How do I know what I need? Is the aim of an exhaust to have less bends?
Yes - the goal is to have less bends.
To eliminate the effect of bends you can use mandel bends.
Think of it this way, when you are drinking a slurpee and bend the straw does it limit the amount you can get? Absolutely. Which is the same effect on a typically exhaust bend.
The way around this is mandrel bends. Without explaining how they're made - the mandrel bends basically gives you the bend, while maintaining the inside diameter of the pipe the whole way. And yes, these bends are more expensive.
quote:
Also I was told that a cat back will give beter mileage true?
I think typically they do. |
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| testingcheck |
| Alright thanks |
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| REFLUX |
Good luck buddy!:bthumbup:
And yeah like TrevorK & scooby_dooby said, 2.25" is good for your purposes |
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| SilverNeonRacer |
The SRT4 comes stock with a 2.25" exhaust 2 14" resonators, no muffler, just as a comparision... heh yet my 02 R/T with 70+hp less has a 2.5" exhaust 1 24" resonator and a highflow muffler, stock.
So yeah... 2.25" or 2.5" would be fine. |
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| scooby_dooby |
ya you don't realyl want to go 2.5" in an n/a integra, unless you're pushin over 170 or 180whp, all that will do is gut your mid-range
if you are planning on making that much power, a header with a 2.5" collector > 2.5" exhaust would be a much better choice.
basically you need to figure out your goals, the last thing you want to do is just start buying pieces and bolting them on. If you plan your whole build, and create a system that works and breathes together you will be much much happier.
If you plan you end goal for whp, you figure out what power-range you want to make poower at, what your budget is.
Those factors will then decide what size exhaust, intake , intake manifold, cams, etc etc you're gonna want to buy.
An engine is a complex system, the more you learn about how it works together, and the different components, the better off you'll be. |
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| Pro Drag |
A good rule of thumb to follow is 1" diameter for every 100 hp your engine makes @ the flywheel.
If you are running a turbo it will provide enough backpressure for the engine and you can generally want 2.5-3", leaning towards 3" for a street car. The goal is to have the least restrictive exhaust possible on a turbo car. |
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| DeathBy240 |
quote:
Originally posted by Pro Drag
A good rule of thumb to follow is 1" diameter for every 100 hp your engine makes @ the flywheel.
So for a stock 240sx the ideal size would be less than 1.5"? |
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| SilverNeonRacer |
well don't most honda's come with a 1" exhaust?
My old swift has a 1.25" exhaust stock with 95hp @ the crank.
:lol: |
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| buh_buh |
on a boosted car, the bigger the diameter the better.
Going from a 2.25 --> 3" I gained 40whp. |
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| Neo-Blue99GASE |
| Now I know this wont answer his question but you also have to look at your vehicle. Im just using my car as an example becasue well, its what I know best. I used 2.5" mandrel bent piping for a good reason, I wanted high-end power. If you look at my previous dyno, im making all my power up to 5000 rpms, and after that, it really runs out. Well with a 2.5" on my V6, I was able to greatly smooth out my torque and hp curves. Now this is for a torqey engine, yours is a more high end hp car and thus, would probably need more backpressure so you dont loose more low end. On the dyno, I lost about 10 WHP and 10 ft-lbs of torque up to 4400 rpms, where my before exhaust hp and torque met with my after-exhaust hp and torque. That said, at peak numbers of only 5500 rpms ( redline is 6000 ), I was making over 30 WHP more and 30 ft-lbs of torque more. In effect, by sacrificing some of my low end, I was able to make some very impressive high end power. Thats is why I chose the piping I did. I only did find this out by talking to alot of other guys who have my car and mods, you might have to do the same to figure out exactly what you want. |
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