noob question here about f.I.... - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

zimzum · 03-06-2014, 01:59 AM

Wasn't sure if I should post this here or in the exhaust area but I figure most of you have tackled this while only a couple have there.

Like many people here I came from a Honda background in my younger/dumber days. I really have enjoyed my brz over the last month and would like to learn more about what goes int the exhaust of a force induction boxer. Three quick questions...

With most cars the turbo exhaust starts with a 3 inch cat/test-pipe and goes through the catback to the mufflers. Since the brz has an over pipe and front pipe does the three inch piping start at the over pipe or is there a gradual gain in size opening?

Also with a supercharged setup is the aftermarket header that many use for NA still able to keep up the supercharger or do most kits come with there own?

I have seen some people people running a full 3 inch exhaust on there NA cars because the plan on doing F.I. in the future. In the Honda world a 3 inch exhaust on NA had huge power drops in street cars and was usually only done by people with fully built H22 or K series engines. What kind of loss, if any do these people tend to get with the twins?

Thanks for any help you can give me.

nood edit

zimzum · 03-06-2014, 02:22 AM

yeah, I always surprised by the amount of people that ran a 3 inch exhaust because they were getting a boosted later down the road. I guess its as bad for this vehicle as it is for others. Thanks.

cdrazic93 · 03-06-2014, 03:56 AM

I wouldnt reccomend anything larger than a 2.5" for an NA setup. Even boosted this motor is still small enough to have a need for back pressure. The FBM shop car that was pushed to 600whp was done (as informed me by another member) on a 2.118" exhaust.

Gains from a 2.5" and a 3" on a daily vehicle under or at 300whp isnt going to be much. I recently saw the AVO turbo FRS at an import meet at the end of feb, and Paul said it was all a 2.5" exhaust from the headers back still making 265whp.

Im no exhaust expert but others would probably best me in their answers.

ZionsWrath · 03-06-2014, 03:58 AM

Who else came to see if OP was a female posting pics.

cdrazic93 · 03-06-2014, 03:59 AM

Quote:

Originally Posted by ZionsWrath

Who else came to see if OP was a female posting pics.

lolwut

ZionsWrath · 03-06-2014, 04:04 AM

Quote:

Originally Posted by cdrazic93

lolwut

Thread title says nood

Wheres the noodz

cdrazic93 · 03-06-2014, 04:09 AM

Quote:

Originally Posted by ZionsWrath

Thread title says nood

Wheres the noodz

.................................................. ............I second this.

zimzum · 03-06-2014, 05:24 AM

Quote:

Originally Posted by ZionsWrath

Who else came to see if OP was a female posting pics.

thanks for catching that. Im using a Surface Pro , have to wait till Friday for my keyboard to come in.

03-06-2014, 01:59 AM	#1
zimzum Member Join Date: Jan 2014 Drives: h22 hatch Location: houston Posts: 53 Thanks: 14 Thanked 2 Times in 2 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	noob question here about f.I.... Wasn't sure if I should post this here or in the exhaust area but I figure most of you have tackled this while only a couple have there. Like many people here I came from a Honda background in my younger/dumber days. I really have enjoyed my brz over the last month and would like to learn more about what goes int the exhaust of a force induction boxer. Three quick questions... With most cars the turbo exhaust starts with a 3 inch cat/test-pipe and goes through the catback to the mufflers. Since the brz has an over pipe and front pipe does the three inch piping start at the over pipe or is there a gradual gain in size opening? Also with a supercharged setup is the aftermarket header that many use for NA still able to keep up the supercharger or do most kits come with there own? I have seen some people people running a full 3 inch exhaust on there NA cars because the plan on doing F.I. in the future. In the Honda world a 3 inch exhaust on NA had huge power drops in street cars and was usually only done by people with fully built H22 or K series engines. What kind of loss, if any do these people tend to get with the twins? Thanks for any help you can give me. nood edit Last edited by zimzum; 03-06-2014 at 05:26 AM.

03-06-2014, 03:56 AM	#3
cdrazic93 Junior Join Date: Aug 2013 Drives: a car Location: Probably at school Posts: 4,341 Thanks: 3,184 Thanked 2,512 Times in 1,502 Posts Mentioned: 20 Post(s) Tagged: 0 Thread(s)	I wouldnt reccomend anything larger than a 2.5" for an NA setup. Even boosted this motor is still small enough to have a need for back pressure. The FBM shop car that was pushed to 600whp was done (as informed me by another member) on a 2.118" exhaust. Gains from a 2.5" and a 3" on a daily vehicle under or at 300whp isnt going to be much. I recently saw the AVO turbo FRS at an import meet at the end of feb, and Paul said it was all a 2.5" exhaust from the headers back still making 265whp. Im no exhaust expert but others would probably best me in their answers. __________________ "Ah! What music! They could have never imagined, those pioneers who invented the automobile, that it would posses us like this, our imaginations, our dreams. Men love women, but even more than that, men love CARS!"-Lord Hesketh

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03-06-2014, 02:22 AM	#2
zimzum Member Join Date: Jan 2014 Drives: h22 hatch Location: houston Posts: 53 Thanks: 14 Thanked 2 Times in 2 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	yeah, I always surprised by the amount of people that ran a 3 inch exhaust because they were getting a boosted later down the road. I guess its as bad for this vehicle as it is for others. Thanks.

03-06-2014, 03:58 AM	#4
ZionsWrath Thanks Join Date: Apr 2013 Drives: BRZ Location: NY Posts: 4,163 Thanks: 5,989 Thanked 3,100 Times in 1,498 Posts Mentioned: 38 Post(s) Tagged: 3 Thread(s)	Who else came to see if OP was a female posting pics.

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