IW STi Forum banner

1 - 20 of 23 Posts

·
Registered
Joined
·
834 Posts
Discussion Starter #1
ok so here it is. my buddy has an older impreza that we tore down and we are putting a stock wrx turbo setup on it. and he bought this monster 4" bell mouth downpipe. well its looking like the clearances arent going to be right for this downpipe to work on his car so we are going to make our own to fit in there. anyways my question. this is a wrx downpipe. from what I understand it will bolt right onto the STi. so if I were to bolt this bad boy on my sti would I see any increases in power without loosing my stock exhaust. my buddy is willing to sell it to me pretty cheap and I would go ahead and do it. but I dont want to worry about boost creep issues as of right now I will be getting a ebc a little later on. but I am really waiting to get all of my guages in, and the new txs piggyback before I go into messing with the motor. I just figured if I could get away with this downpipe for now it would be great. so any info would be greatly appreciated!!
 

·
Registered
Joined
·
5,261 Posts
A downpipe + stock exhaust will still net HUGE gains... my downpipe on stock exhaust felt like a rocket ship. Felt like all my previous mods put together. Boost creep does not come from a downpipe (unless its designed crapily) but a full open 4" bellmouth wont do that. Also... the ONE and ONLY thing to FIX boost creep is porting the wastegate. Other stuff might help, but is NOWHERE near enough. I hit 19psi+ boost creep WITH ebc and slight port... so just do it right or you will not ever fix the boost creep problem. But yes a downpipe for now wont harm anything and will yeild great results... have at it!!

Robert~
 

·
Registered
Joined
·
834 Posts
Discussion Starter #3
ok, but just to clear this up a little bit. its not only a 4" bellmouth. it is a full 4" downpipe. I do not know the brand but it is friggin huge. maybe even too big?
 

·
Registered
Joined
·
5,261 Posts
althought not needed (4")... if it fits I guess it'll work. I dont know how it will perform though, that sounds very big. The only car that requires something that big is a T88 or so Supra... thats because they run turbos the size of Semi's turbos ;) good luck, just od it and see how it works out.

Robert~
 

·
Registered
Joined
·
834 Posts
Discussion Starter #5
yeah, I think I might bolt it up tomarrow and see what happens. but hey, while you are on the subject of semi turbos. My friend is a mechanic at our local frieghtliner dealer, and they just got the new CAT diesel trucks in. 3 turbos on these bad boys. and these are by no means 3 smaller turbos than the single turbo engines. these are 3 huge turbos. I will have to take a picture sometime.. haha
 

·
Registered
Joined
·
5,261 Posts
lol ya I work at a GMC Semi Dealership :). lol I love studying how all that stuff works as its like a car's but only HUGE and you can go through the open engine and see how it all works.

Robert~
 

·
Registered
Joined
·
834 Posts
Discussion Starter #7
yea, it is neat.. lol I went through and looked over some of the motors he was working on and everything. I also have a few valves and pistons that he took home pistons cracked completely around. those truck drivers are just brutal on their trucks. The other day I stopped down and the boss came out to look at my car, says he never heard of an STi but he wanted a wrx since they came out. he saw my car then called his wife and told her he is buying a new car this weekend.. haha he is getting a brand new one for around $27000 because of dealer connections.. wish I knew that before I bought mine. haha the things I could do with the extra $2500
 

·
Registered
Joined
·
5,261 Posts
Yes.. but i think he meant 4" Downpipe, like 4" belltmouth - 4" downpipe, not 4" bellmouth into a 3" pipe like turboXS. Thats the reason he has concern.

its not only a 4" bellmouth. it is a full 4" downpipe.
Robert~
 

·
Registered
Joined
·
759 Posts
staticx313 said:
Yes.. but i think he meant 4" Downpipe, like 4" belltmouth - 4" downpipe, not 4" bellmouth into a 3" pipe like turboXS. Thats the reason he has concern.

its not only a 4" bellmouth. it is a full 4" downpipe.
Robert~
Whoops. I missed that post.
TXS is a 4" downpipe that tapers to 3" at the cat. It is not a 4" bellmouth with a 3" pipe. A little clarification. :D
 

·
Registered
Joined
·
411 Posts
NewGenSTi said:
ok, but just to clear this up a little bit. its not only a 4" bellmouth. it is a full 4" downpipe. I do not know the brand but it is friggin huge. maybe even too big?
Wow, never heard of a full 4" downpipe. Let us know how it works out, and provide pics.
 

·
Registered
Joined
·
834 Posts
Discussion Starter #13
Widest rim for racing ? (autocross/road race)

I will take some pictures of the process and let you all know how it works out. I just got done washing the car and when I went outside with it my check engine light came on and my cruise light is flashing. I think I remember reading about this before but I do not recall for what reason. I think it has to do with the cold maybe? it was 1 degree when I pulled it into the garage, and the garage is about 75 degrees, then I pulled it back outside to go to the bank and it was only 3 outside and the lights came on. ahh I hate electronics.. haha
 

Attachments

·
Registered
Joined
·
5,261 Posts
You have a CEL and such because you are catless... to fix this you will need to weld on an extnesion on the 02 sensor or buy one of the CEL fix kits.

Robert~
 

·
Registered
Joined
·
834 Posts
Discussion Starter #15
I didnt put the DP on yet.. haha. I washed the car and pulled it outside. it is still bone stock? still runs fine. I am headed to autozone in a few minutes to pull the code and have it erased. and just out of curiousity, where can I find one of these cel fix kits that you mentioned because I will probably need one after I put the dp on
 

·
Registered
Joined
·
834 Posts
Discussion Starter #16
figured out the cel light. my gas cap had a little bit of moisture on it that froze up I wiped it off of the o-ring re-tightened the gas cap and started the car back up. no more cel.. anyways Im gunna make this short I just picked up the downpipe I have a picture below. you can see this is a monster almost like a 2 stroke dirtbike pipe. haha well I am going ot go start the work now and see how this bad boy works. it isnt a full downpipe. its just the first half? it only replaces one cat, and it leaves the o2 sensor untouched after the second cat. we wil lsee how it works
 

·
Registered
Joined
·
834 Posts
Discussion Starter #20
as you can see by the pictures this pipe is just huge. it is a 4" bellmouth 4 inch all the way through and it tapers at the very end to 3" the flange wouldnt bolt up with the stock second half of the system and it also ran about 6 incehs too far. so tomarrow morning at around 8:00 I am heading out to pick up some parts and I am going to make a pipe to fit what I need. I already have some 3 inch tobing around but I will be needing a reducer to go from 3" down to the factory 2.5" piping at that litttle ball connector. I am going to weld a flange onto the 3 inch pipe that will match up with the one on there now and another on the other side so I can use the stock mounts. I am also going to throw a bung in for the o2 sensor and probably raise it up out of the pipe so that I dont get and CELs once this thing is back together. as you can see by the pictures I managed to snap a stud off on my turbo so I need to pick up a stud remover and probably a whole new set of studs for it so I dont have any more breaking when I put it back together. I will take more pictures of everything else tomarrow and post them for everyone along with my review of this. but for now I am going to bed. I have a long day ahead of me tomarrow, and its 1:35 a.m. now.
 
1 - 20 of 23 Posts
Top