I am getting Hooker Shorties 2460 and need a y-pipe. I was told that a 3" y-pipe will actually make me lose backpressure and power. I am just wondering if its better to go from 3" collectors to 3" y-pipe to 3" cat to 3" cat-back to 3" tips

Or

3" collector to 2.5" y-pipe to 3" cat to 3" exhaust to 3" tips

Or

3" Collector to 2.5" Y=pipe to 2.5" cat (hi-flow of course) to 3" cat-back to 3" tips.

All this losing of power between 2.5 and 3" is alot to me so let me know guys. thanks.

 

Keep it all 3". You'll be fine.

 

all 3'' its better for now, and in the future..

 

3 all the way through to go less would be just like the stock crap and its better bc u shrink the size anywhere in the exhaust and it doenst matter how big any part of it is bc exhaust is only as good as its smallest part.

 

Okay thanks guys. my buddy kept telling me stuff like when he had his full 3" exhaust that he got more power when he went to 2.5" y-pipe and cat. But yes for down the road I will need that 3". Considering Im stroking my LO3 and camming it with a nice tune. Would like 350HP...I mean 350TQ out of this motor before I buy my 350...Oh Yeah! That or 12's. Whichever comes first. Then I can swap over the parts. thanks a lot. Let me know if dumping the exhaust (with QTP Cutout) right before the cat (pointing towards middle of car) would lose me power as the Backpressure thread states something like that....*scratches head* I think.

Also let me know if right before the cat would be a good place. Thanks.

P.S. Some people were stating how loud their cutouts made the inside of the car. I cant find that thread but I know alot of people had many different opinions on where to install a cutout...I dont want to blow my ears out so...once again let me know...sound clips, video clips, pictures would help my decision.

P.S.S. What is everyone running for their exhaust from Header Collector on back?

-Still Hating That Front Wheel Drive !BS!

 

u dont need a cutout with your 305 u will prob lose power even if its putting out 350hp and tq. even a properly built 350 with more than that wont benifit from a cutout, a good low backpressure 3" exhaust will flow enough for 400hp a cut out will help if ur running more than that like 450, 500.
and the cutout under the car will make it alottt louder but cutouts are usually only for track use so ppl bare with the noise when at the track. it wont blow ur ears out but it will get annoying real fast.

i dont have shorties, or a ypipe etc.
im runnin headman longtubes, 3" headman sbends 3" xpipe into 3" force mufflers and i have wayyyy to much exhaust for my modded 350tpi but i did it for the sound and for a 500hp383 down the road.

 

So my shorties will be fine for my 305 then and full 3"?

 

Yeah, you should be fine with that setup.

 

Thanks much.

 

Funny how you're worried about the y-pipe when the 1 3/4 inch primaries and 3" collectors are way to big for your 305. They would best suited to a potent 350 that you have planned for the future that I missed in your other post.

 

keep it simple, good set of shorties and 3" inch all the way to the tips and your good for even a heavily build 305. And it should also be good for a well modded 350.

Pat

 

Next winter I'll have 6 months Nov-April to gather money. I have estimated quickly around $5g over those 6 months Ill have to spend. Am going to wait until April to buy everything. Summits going to love me.

But for right now I am just buying some parts that will help out my 350 when I get it next summer.

P.S. What do you recommend matt_p for Headers and exhaust setup on an LO3 305?

 

Hedman 1 5/8 primary headers. A low revving 305 just doesnt produce enough power to make use of the 1.75" primaries. The exhaust gases expand to much and thus slow down reducing the scavenging effect far too much. They basically become tubular manifolds.

A local guy with a 305 TPI did a before and after at the track. His ET stayed basically the same and only gained 2 mph. No gain in the 60 ft or anything else. No torque was gained at all. The low power 305's only go faster because for crappy restrictive log manifolds are gone.

The only two guys to need those larger headers, that I know of, on this board are mw66nova and Fast355. They are both making over 400 horsepower in the 6500 rpm range, and peak torque in the 4500 rpm range.

1 5/8" primaries will be smaller so you will gain torque but they aren't too small to restrict horsepower unless you want to make power around 6000 rpm's. 1.5" is optimal for a low revving 305. But they aren't made and will become too small as soon as you mod.

3" collectors are too big because the exhaust gases slow again one the exhaust gases exit the primary, reducing scavenging even more on the other primaries.

Unfortunatly, pretty much every header made for our cars out there have 3" colletors so your stuck with them unless you want to cut them off and weld 2.5" ones on.

 

I agree with matt however....

I think I H8 WWD is planning to use the same headers on his 305 and later swap them onto his 350 to save money and to avoid repurchasing headers. In this case go with the 1 3/4 primaries.

Basically whats going to happen is as you build up your 305 or 350 (especially if you choose the 350) you will probably want more and more power and your powerband will increase from 2.5k-4.5k to 2.5k-5k and one day 3.0k-6k, and once you hit that 6k rpm range and beyond you will need the 1 3/4 primaries. Although you will not maximize the full potential of the 1 3/4's now(you will notice a difference between your stock exhaust to a 1 3/4), it will save you time and money down the road.

Here are 2 links to a website that i think will benefit you in general especially if you decide to kept your L03 setup, it is a long read but it will explain a lot of the grey areas you may have.

http://www.goingfaster.com/spo/modthel03.html
http://www.goingfaster.com/spo/praisetbi.html


Hope this helps,

Pat

 

Thanks alot....Read the first already and will now get into the second. Much thanks.

 

fwiw, i'm only running a 1 5/8" primary longtube header...

 

fwiw???

And I am lowering my car with coilovers for track use so I dont think I could ever get long tubes how I like. Anyone have a lowered car with longtubes?

 

FWIW = For what its worth

 

Gotchya.

So any lowered F-bodies with long tubes

 

mine was pretty well slammed with longtubes and dual 2.5" pipes for a while.

 

You have pictures. If not, did you ever scrape the ground or bump the exhaust?

 

I have longtubes, and i live in Louisiana. The roads are horible and i bottom out all the time. Not one mark or dent on my headers. I scrape the rest of the exaust bad tho. Mossly because it isent done right, just did it to get exaust on the car.

 

Anyone have emissions cat check? I have to have a cat...for emissions checks, so I am looking into single exhaust with cat because I dont think true duals with two cats will be fine?

 

I H8 WWD i have those tests too since i live in CA. I didnt think i would pass smog with 2 cats either since my car came stock with 1 but i was talking to my auto teacher and he said that 2 cats would be fine and that the just check to see if you have any hooked up.

 

I have a single cat. I think I might go with Hedman Shorties until I have money to make up true duals with crossmember with dual cats and hookups all the way back. I will let you guys know how my tests are when I get my Hedmans.

I have to find out how far you can go before you dont pass emissions....especially in Ohio.

 

I have hooker headers, going to custom y pipe 3" going to hiflow cat then thru flowmasters. The high flow cat is just a little above a straight pipe. You can even see thru it. The car sounds great thru the flowmasters, just loud. That is because of the cat. Could defintly tell more power.

 

I am thinking about going this route.

Hedman Hedders- HED-68470
Custom 3" Y-Pipe- CUSTOM (Might get 2.5" custom)
Magnaflow Cat- MPE-93441 (Might go with 2.5" Cat)
Flowmaster Cat-Back- FLO-17234

I need some backpressure so....thats why I might go with the 2.5" y to cat then 3" the rest of the way out.

 

No, you don't.

 

As you can tell I didnt get much from the backpressure thread. Lol. So going with 3" from collectors back will be fine then. If so thats what I'm gunna do. Thanks.

What do you run on your 305???

and your 383?

LMK, Thanks again.

 

go 2.5 to cat then 3" all the way for the velocity to prevent backpressure and stay legal

I just responded somewhat at length to the ( 2.5 or 3" thread ) to explain why please read , should help .

 

2.5 seems to be the best. Thanks guys.