3" after 2.25" y pipe, waste of money?
#1
Senior Member
Thread Starter
Join Date: Feb 2002
Location: saugerties new york
Posts: 885
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91 firebird,mint
Engine: 305 tbi,lots of work done
Transmission: 700-r4 built by level 10 in nj
Axle/Gears: 3.73, auburn , precision
3" after 2.25" y pipe, waste of money?
well i have to add a cat or i wont pass inspection, right now i have 2.25" y pipe and 2.25" all the way back to a flowmaster , no cat..........................i was going to have them change it to 3" after the y pipe, with a catco cat and a hooker aero chamber, think this is money well spent or should i just have em throw a 2.25" cat in?
#2
Senior Member
Thread Starter
Join Date: Feb 2002
Location: saugerties new york
Posts: 885
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91 firebird,mint
Engine: 305 tbi,lots of work done
Transmission: 700-r4 built by level 10 in nj
Axle/Gears: 3.73, auburn , precision
well a summit tech told me he wouldnt go any bigger than 2.50 " on a 305 cube motor...................he said id lose alot of scavenging with 3" which isnt good............you guys agree?
#3
Junior Member
Join Date: Feb 2004
Location: vermont
Posts: 14
Likes: 0
Received 0 Likes
on
0 Posts
Car: 84Z28
Engine: 305,s/r torquer heads,cam,headers
Transmission: 700 r4
bull ,i just went from a dynomax 2.5 cat back to a 3 " banks and change my hedman y pipe to 3 where the pipes come together to the cat and let me tell you what a differnce. i had a bog off the line i couldnt tune out now with the 3" no more bog and more throttle responce and power. took me and my friend about 2 hours to do the job at his shop. i would have the shop do the same to your y pipe.
#4
Senior Member
iTrader: (1)
Join Date: Nov 2002
Location: Kansas City
Posts: 889
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1991 Trans Am
Engine: L98
Transmission: T56
Originally posted by onebad84z28
bull ,i just went from a dynomax 2.5 cat back to a 3 " banks and change my hedman y pipe to 3 where the pipes come together to the cat and let me tell you what a differnce. i had a bog off the line i couldnt tune out now with the 3" no more bog and more throttle responce and power. took me and my friend about 2 hours to do the job at his shop. i would have the shop do the same to your y pipe.
bull ,i just went from a dynomax 2.5 cat back to a 3 " banks and change my hedman y pipe to 3 where the pipes come together to the cat and let me tell you what a differnce. i had a bog off the line i couldnt tune out now with the 3" no more bog and more throttle responce and power. took me and my friend about 2 hours to do the job at his shop. i would have the shop do the same to your y pipe.
original poster: depending on what your future mods are, a 2.25 y pipe will be the restriction before even a 2.5 inch catback would be. if its cheaper by any substantial amount to go 2.5 inch for the rest of the ehxuast i woudl do that unless you have honest plans for bigger cubes or a better top end for the 305.
#5
Senior Member
Thread Starter
Join Date: Feb 2002
Location: saugerties new york
Posts: 885
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91 firebird,mint
Engine: 305 tbi,lots of work done
Transmission: 700-r4 built by level 10 in nj
Axle/Gears: 3.73, auburn , precision
well first off my motor isnt stock , ive done everything cept cam and heads.................ill list later....................my y pipe im going to leave 2.25 because i was having a scraping issue and i dont want to have it again, so i was only going to change from the y pipe down to bigger, 3 or 2.5............................
msd 6a box
accell coil
accell plugs
msd wires
dual snorkel with k&n ( ran both hoses down into the air dam)
edelbrock tbi intake
flow matched injectors
injector spacer
tb spacer
adjustable fuel pressure reg (running 16 psi)
crane 1.5 roller rockers
griffin radiator
be cool tranny cooler with fan
tranny rebuilt by level 10 in nj
aluminum tranny pan
helwig sway bars front and back
3.73 precision gears with auburn posi
aluminum driveshaft built by dennys driveshafts
kyb shocks and struts
panhard bar
hooker 2138 headers (1.5 primaries into 2.25 y pipe)
accell heated o2 sensor
i may have missed something, the bottom end hasnt been touched yet but i do have an slp cam (51002), i just havent had the money to get edelbrock e-tec 170 heads and a different manifold( different bolt pattern , name escapes me now)
but the summit tech said no matter what i do to a 305 3" is too big.................
msd 6a box
accell coil
accell plugs
msd wires
dual snorkel with k&n ( ran both hoses down into the air dam)
edelbrock tbi intake
flow matched injectors
injector spacer
tb spacer
adjustable fuel pressure reg (running 16 psi)
crane 1.5 roller rockers
griffin radiator
be cool tranny cooler with fan
tranny rebuilt by level 10 in nj
aluminum tranny pan
helwig sway bars front and back
3.73 precision gears with auburn posi
aluminum driveshaft built by dennys driveshafts
kyb shocks and struts
panhard bar
hooker 2138 headers (1.5 primaries into 2.25 y pipe)
accell heated o2 sensor
i may have missed something, the bottom end hasnt been touched yet but i do have an slp cam (51002), i just havent had the money to get edelbrock e-tec 170 heads and a different manifold( different bolt pattern , name escapes me now)
but the summit tech said no matter what i do to a 305 3" is too big.................
#6
Supreme Member
iTrader: (2)
Join Date: Jul 2004
Location: Miami
Posts: 1,678
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1992 Camaro RS
Engine: L03
Transmission: 700R4
Axle/Gears: Stock
Originally posted by wasp
but the summit tech said no matter what i do to a 305 3" is too big.................
but the summit tech said no matter what i do to a 305 3" is too big.................
But think ahead a few years...when the 305 quits, you're gonna have to drop in a bigger motor, and the 3" would be nice to have. Also, cheaper than a 2.5" and then a 3" exhaust. And if for no other reason: why not?
(Besides, the guy is just trying to sell you a crate engine)
#7
TGO Supporter
Join Date: Oct 2002
Location: Saskatoon, SK, Canada
Posts: 9,067
Likes: 0
Received 1 Like
on
1 Post
Car: '83 Z28, '07 Charger SRT8
Engine: 454ci, 6.1 Hemi
Transmission: TH350, A5
Axle/Gears: 2.73 posi, 3.06 posi
Two 2.25" pipes flow the same amount of air as a single 3" pipe, from what I've read from past discussions. So, when your 3" single becomes a restriction, your 2.25" Y-pipe will at more-or-less the same time.
a 3" DUAL exhaust is way too big for a 305, and even some big blocks... a 3" single exhaust system is roughly the same as using a 2.25" dual exhaust system, which is just about right for a decent 305 or 350.
a 3" DUAL exhaust is way too big for a 305, and even some big blocks... a 3" single exhaust system is roughly the same as using a 2.25" dual exhaust system, which is just about right for a decent 305 or 350.
Trending Topics
#8
Senior Member
Thread Starter
Join Date: Feb 2002
Location: saugerties new york
Posts: 885
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91 firebird,mint
Engine: 305 tbi,lots of work done
Transmission: 700-r4 built by level 10 in nj
Axle/Gears: 3.73, auburn , precision
ah , so the 2.25 y flows almost the same as the single 3? well it does go into a single 2.25 pipe for about 10" or so............perhaps 3" is the way to go then
#9
Member
Join Date: Nov 2003
Location: Maryland
Posts: 389
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1992 Camaro RS
Engine: 305 L03
Transmission: Borg-Warner WC T-5
Go 3", as long as you have stock manifolds and y-pipe going 3" with the cat and cat-back won't hurt you at all. I did this, I have stock manifolds and y-pipe going into a 3" Catco direct-fit and a 3" Flowmaster American Thunder. It sounds bad *** and it did not hurt performance at all. The mods you have right now are more than justified for a 3" cat-back.
#10
Supreme Member
Join Date: Oct 2001
Location: Louisville, Ky
Posts: 3,155
Likes: 0
Received 2 Likes
on
2 Posts
Car: 1991 Z28
Engine: 383
Transmission: T-5
Axle/Gears: 3.08 10 Bolt
i have that same issue, no cat but my headman 1 5/8 headers came with a small y pipe and i have a 3" mandrel exhaust the rest of the way back. i know the y pipe is holding me back and because its so small compared to the rest of the piping it is a crappy job trying to get the two to meet together
#11
Senior Member
Thread Starter
Join Date: Feb 2002
Location: saugerties new york
Posts: 885
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91 firebird,mint
Engine: 305 tbi,lots of work done
Transmission: 700-r4 built by level 10 in nj
Axle/Gears: 3.73, auburn , precision
i have headers vnate.................camaro.............dont they make 3" to 2.25" reducers? how else would the shop do it?
#12
Junior Member
Join Date: Feb 2004
Location: vermont
Posts: 14
Likes: 0
Received 0 Likes
on
0 Posts
Car: 84Z28
Engine: 305,s/r torquer heads,cam,headers
Transmission: 700 r4
What we did to my y pipe was cut it where they merge into one and weld a 90 degree and 45 degree bend cut to fit and mig weld it together,now i have two 2 1/4 into a 3" pipe instead of going into a 2 1/2 pipe. i am sure a shop could do the same to yours.
#13
Senior Member
Thread Starter
Join Date: Feb 2002
Location: saugerties new york
Posts: 885
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91 firebird,mint
Engine: 305 tbi,lots of work done
Transmission: 700-r4 built by level 10 in nj
Axle/Gears: 3.73, auburn , precision
i was looking at reducers on summit, none go from 2.25 to 3 , but they have a 2.25 to 2.5 and a 2.5 to 3..................should i get these when i order the muffler and cat? cant the shop just widen the end of the pipe on the machine? or not that much
#14
Member
Join Date: Nov 2003
Location: Maryland
Posts: 389
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1992 Camaro RS
Engine: 305 L03
Transmission: Borg-Warner WC T-5
Any good exhaust shop should be able to make or find a reducer to put from the 2 1/4 Y-pipe to the 3" Cat. That's how mine is set up and they did a dang good job welding the reducer in. I'll have to take some pics when the rain stops.
#15
Senior Member
Thread Starter
Join Date: Feb 2002
Location: saugerties new york
Posts: 885
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91 firebird,mint
Engine: 305 tbi,lots of work done
Transmission: 700-r4 built by level 10 in nj
Axle/Gears: 3.73, auburn , precision
what about from the catback? im going to purchase a hooker aero chamber muffler, i have a flowmaster now and wana try something different......................should i buy a cat back system or let the shop make it, which do you think would be cheaper?
#16
Originally posted by wasp
well a summit tech told me he wouldnt go any bigger than 2.50 " on a 305 cube motor....
well a summit tech told me he wouldnt go any bigger than 2.50 " on a 305 cube motor....
He probably wouldn't go any larger on a 305 since they didn't have a larger one in stock, would be more my guess. He gets no commission on a no-sale.
#17
Senior Member
Thread Starter
Join Date: Feb 2002
Location: saugerties new york
Posts: 885
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91 firebird,mint
Engine: 305 tbi,lots of work done
Transmission: 700-r4 built by level 10 in nj
Axle/Gears: 3.73, auburn , precision
well i see what your saying but the tech line is different from sales, he said hed change to 2.5 but not 3 as the motor would be pushing the exhaust more than the pipe helping to pull it, he mentioned a few different types of pulses...........
Thread
Thread Starter
Forum
Replies
Last Post
Bohemian
Aftermarket Product Review
11
11-25-2015 09:38 PM
[Sold] Flowmaster exhaust system
Night rider327
Engine/Drivetrain/Suspension Parts for Sale
4
10-09-2015 09:25 AM