2 1/4" exhaust?

[aussiegen3]

grettings all,

ive recently considered equiping my 3gee (89-si) with a new exhaust.
i was thinking 2 1/4 inch with a hi flo cat, to big or to small?

if i was to go with this size what sort of performance increase whould i expect? i'm also planing on adding a short ram intake with either K/N or AEM filter.

i'm in austrailia so finding a set of headers is nearly imposable, getting a mandrel bent exaust made up is much mucj cheaper.

[SteveDX89]

2 1/4" is the perfect size. I noticed a bit more torque especially on highways going uphill. I don't have to downshift as often. I can just hit the gas and it goes. I also noticed that I don't have to downshift as much when slowing down. If I slow down and the rpms are down to like 1500, I don't have to downshift to a lower gear to go again. I can just ease into the gas and she goes.

[shepherd79]

still, you should get headers. they will help a lot.

[aussiegen3]

i was thinking the 2 1/4 because a friend of mine just got one put on his 92 integra and it made a huge differance heaps more grunt in the top end.

[rjudgey]

Definately get 2 1/4" min if running N/A if going to go turbo get 2 1/2" as future proofing. headers can be made any descent exhaust place should be able to make something up and wnything is better than the stock cast POS, although i still use mine but you can port flow and polish it which help a bit a few bhp can be had. But Headers can be bought just mail order them, S&S headers have a website and do world mail order, they are pretty cheap too and do loads of different designs. Also PAcesetter if your on a really tight budget. Also worth noting most the pre made headers only have 2" collectors to the main pipe so ideally get one made up that goes to 2 1/4" and also get a cat replacement pipe made up.

[SteveDX89]

Oh yeah. Forgot to mention that getting a bigger pipe will prevent you from having a weedwhacker/angry bee/fart can sound from your exhaust.

[rjudgey]

my stock exhaust sounded good and was only 1.75" but then having the twin Webers probably helped ;0) But at 170bhp started to cause the exhaust to fall apart from the huge backpressure created!! changed to 2 1/4" with new downpipe and ported flowed poilshed manifold gained a easy 20-25bhp was like a wild animal afterwards was scray to drive for the first few days then got use to it and now i want more!!!!
So 4-1 with new big valve head conversion and a wild cam and hopefully should see me to new levels of exhilleration!!

[1988starter]

what what did you do to your car to get 170 bhp on an a20

[rjudgey]

173.6 bhp at the wheels i have my own onboard diagnostics and meters, as long as figures for car weight, driver weight and howmuch fuel are correct, combined with drag co-efficency readings and a few other measurements are correct it's pretty accurate.
but secret to my engine is that the build is immaculate/clean/blueprinte
all measuerments/clearances are spot on and re-checked. i do all my own engine work only i don't do is surface grinding, boring and cam grinding, everything else i makesure is done myself, headwork, port matching, carb mods, assembly and any work on the car itself. Don't trust any other engine builder or mechanic been ripped off so many times that i learn't everything for myself took a while but over 5 years i've successfully squeezed more power outta my a and e series (83-85 blocks) engines after each re-build some went well others went horribly wrong only after a few hundred miles! but you have to learn by your mistakes and also by what works and what doesn't! also the engines i have are all hybrids only common parts are blocks a all bored to 2.0litre, pistons are all sealed power which are customized by myself, rings which are specially chosen and hand gapped, rods are the same but stress relieved, polished, balanced etc, crankshaft re-balanced etc, extreme attention to detail in headwork, manifolds and carbs. it is this that really gets the extra horses some people say i'm overkill but if you add up 10 small things that get you extra flow althoug seperately may only produce 1 or 2 extra bhp but times that by 10 you have a huge amount of extra power! and most the time all this can be gained from having just logical thinking in physics and a hella lot of time and patience!
even normal bolt on products you by off the shelf can be improved in some way it's my way of thinking everything i touch i find some way of making it better whether its cars, computers, or R.C models!

[A20A1]

So you're building your own 4-1? I'm going to get to work on a second 4-1 design... but I'm building it out of stainless steel this time. And I'll get a better flange made... I used a grinded stock exhaust flange for my first 4-1. The primary tube routing went a bit crazy cause I didn't have enough subtle bends to get all 4 primaries between the oil pan and the tranny.
My goal was a 4,000 rpm - 7,500 rpm powerband... and I belive I hit that nicely

PICS OF 4-1 HEADER (http://www.3geez.com/showthread.php?t=6466&page=3)

... 3" collector, I couldn't find a 2.5" collector.... the header is also missing the 30" or so of exhaust pipe needed after the collector... which acts like a secondary tube IMO. I tossed on a 2" muffler instead so it has a fair bit of restriction when it goes from 3" down to 2".

Also in the new design I'll include a flange so i can unbolt the pipe after the collector... cause right now if I added a pipe I would never get the header out from under my car unless I get it on a lift.

[BootMachine]

I agree. 2 1/4" exhaust is a good size. I went with 2" a LONG time ago and it was too restricting.

Its old now and falling off so the new exhaust will be a bit bigger!

[aussiegen3]

hey thanks for the info everyone, what exactly can i do to make sure i definetly done get that pathertic fart sound from there rear,

i whould be shattered if i got that sound. i'm after a realy deep sound not nesisaraly load but just deep. i need to be set apart from all those stupid gli lancers in my town with thier stock exhausts and strait though mufflers welded on the end, they sound so crap.

please i need to make sure i wont get that sound, i'm terriefied of it.

heheheh
thanks again

[SteveDX89]

The sound depends mostly on the muffler. Dynomax sounds great. I've got that and it's no where near an obnoxious sound. I've heard that Flowmasters sound good too.

[Justin86]

you will love it. I noticed a gain buy getting exhaust! :)

[PhydeauX]

The collector on the pacesetter is 2 1/4", atleast mine was.

andy

[Bioforge]

I would definately get 2 1/4, along with flowmasters....I have 3" piping (for the hp in the higher rpm's with the s/c, going out to dual 40 series flowmasters, and the sound is imaculate...I also have a Borla resonator to help with air flow restriction, and giving it a deeper roar....But thats just me :)

[1988starter]

I am all about the dynomax super turbo

[Bioforge]

but then thats just known..the only problem with dynomax's is that alot of shops are dicks, and will only weld what they sell...but if you can get ahold of dynomax's, then by all means use'm.