Exhaust size?

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Sparky

Sparky

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After owning my TTI headers for quite some time, I am going to install them.The thing is I have a perfectly good 2 1/4 exhaust system on the car now and I would hate to have to spend 5 or 6 hundred to go to 2 1/2. So the question is how much HP/torque/power will I loose by leaving the 2 1/4 system on the car? It has a 340,auto,Air Gap,670 holly,electronic ignition,355's out back,shift kit, Dinomax mufflers. I do not know what cam as I have never taken the motor apart to find out. I think it is a little lumpier than stock but I do not know for sure. This is primarily a street car, may see a track one day if given the opportunity but I do like it to perform and it does quite well now. I would hate to put the headers on and see no gain if i leave the smaller pipes on.
What do you think? Again not a race car but I do like to keep the Chebby and Ford guys a little nervous.
Thanks
 
2 1/4 especially with those headers is completley a waste. With a 2 1/2 exhaust you will pick up 25-30 horses combined with the headers as well as a ton of torque. Remember to think of an engine as an air pump, you have all the right stuff getting the air in, but your blowing it out through straws which is gonna hurt you a ton on power. You don't have to spend $500 on a 2 1/4 inch exaust, you can get a bolt on setup mandrel bent from summit for $209. Its not stainless but its a diecent setup!
 
streetdak said:
2 1/4 especially with those headers is completley a waste. With a 2 1/2 exhaust you will pick up 25-30 horses combined with the headers as well as a ton of torque. Remember to think of an engine as an air pump, you have all the right stuff getting the air in, but your blowing it out through straws which is gonna hurt you a ton on power. You don't have to spend $500 on a 2 1/4 inch exaust, you can get a bolt on setup mandrel bent from summit for $209. Its not stainless but its a diecent setup!
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Thank you,I will check it out!
 
...........3 inch is a waste unless u have an honest 450 HP..............u can also sell ur 2 1/4 set up , or keep it 2 put it back 2 factory down the line........2 1/2 is ur best bet...............kim...........
 
I think you would be fine with the 2 1/4 for your use and you will still see a gain with the headers. 3" would be overkill for your mild 340.

You have 2 1/4 now and the cost of adapting it to your headers will be very low. Try it out, you will probably be happy but if not you can change to 2 1/2 down the road and not be out anything.
 
2 1/4 that's for slant six and 318 cars.:toothy10::toothy10:you've spent the money on good quality headers now don't get cheap on the rest of the exhaust..trust me your 340 will appreciated the extra breathing room,i run tti's with 3"aluminized pipe to the mufflers 3" in 3" out,with 2 1/2" tailpipes,factory stainless tips.. sounds and looks great...yes it can be pricey but when done properly its worth every penny spent..oh for your car i think 2 1/2 all the way would do the trick..
 
ya 2 1/2" would be best if you spend most of your time at 4 to 6k rpm, but if you just cruse around with a stomp on the peddle every once and a while i wouldn't worry about it. if your straped for cash and think you need the breathing get 2.5" from headers to muffler and leave the tails 2.25".
 
your motor sounds very mild, you will feel a big difference with the TTi's even with 2.25". 440+6 and hemis had 2.25" not ideal but still ran fast!
 
Go to Summit or Jegs for the exhaust system. I used there 2-1/2 inch system on my Duster. It fit well and was easy to install with only minor tail pipe trimming involved. Cap them in chrome tips and your looking good.

They come with and without mufflers. With mufflers, I beileve I paid $200. Without mufflers, the savings is slight though you can then choose what ever muffler you want .

It is a true dual pipe system, no X or H pipe.
 
I think the write up on Summit said they were desighned to hook up to Hookers so so sme modifications may be required. Anybody hooked the Summit sytsen to TTI?, minor mods?
Thanks for all the help guys.! :cheers:
 
Your butt dyno will not be able to tell the difference between the 2 1/4 and 2 1/2. I would just install the headers and down the road if the money presents itself or the exhaust needs replacing go 2 1/2". The only thing 3" will do for you is make more noise.

My Barracuda orignally had a \6 with 6 into 2 headers. My ex father inlaw bent up a 2 1/4" dual system with an H-pipe for it at his muffler shop. When I swapped in the 360 (~370 HP) I just adapted the 2 1/4" system to the headers on the 360. My daughter was working for her grandfather at the muffler shop and offered to do a new system for me as a fathers day gift. I had her do a 2 1/2" system with an x-pipe and 50 series flowmaster mufflers. I could not tell any difference by the but dyno in the power between the two systems.
 
Wow, I am getting answers from both ends of the spectrum, complete opposite. Very interesting and slightly confusing. I will have to do some research and figure it out...keep the knowledge coming....

Thanks
 
Sparky, the way the header kit is made is easy to modify to hook up to any header.

DGC is probably more right about the butt dyno. It should show on a slip though. IMO, anything at 300 + HP could use 2-1/2 pipe.
 
Sparky said:
Wow, I am getting answers from both ends of the spectrum, complete opposite. Very interesting and slightly confusing. I will have to do some research and figure it out...keep the knowledge coming....

Thanks
Click to expand...


I think the reason you are getting conflicting answers is the mild combo you have.

If you needed exhaust from the headers back I would tell you 2 1/2" too. It opens up more options in the future.

For what you have (mild 340) and seeing that you already have a 2 1/4 system, running what you have is win/win. You are out less cash and aren't losing much if anything in performance.

Moving to 2 1/2" is something you can do anytime.
 
An internal combustion engine is like a big air pump.. the faster you get it in.. the faster you get it out.. the faster you go..2 1/4 might be ok for a little 318,but your running a performance "340" it'll benefit from the larger pipes and those nice headers:-D:-D

As for some not noticing a difference between the 2 do you actually run your car all out(race it) or do you just putt around on the street??
 
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