'04 Sportivo 2zzge engine power loss

[rchut1]

Hi there,
I recently took my corolla in to get an exhaust change. The mechanic was a exhaust specialist he fully changed the exhaust adding basically a straight pipe with two 1/2 resignators and a 3" cat convertor. after the mechanic changed the exhaust i've noticed a significant power loss my car certainly feels heavily affected, I wont lie its the most insane noise you have ever heard I cant drive anywhere without every person turning there head , even when the lift starts at 6k it basically feels the same the whole way through. i'm now wondering if I should replace the exhaust back to stock. does anyone know why im losing power or what I can do to fix my problem. thank you for your time

too add my previous 0-100 in this car was 5.9 seconds now its 7.5-8 with this current custom exhaust 

[Squalled]

So from my understanding, the whole exhaust is changed which includes headers as well? What size piping did you use for the new exhaust system? I haven't related to this ever since modding my Sportivo but have noticed a fair few guys recently having the same problems.

[jeffy]

having some doubts with your exhaust "specialist" mechanic.. because ive never heard of such a thing, but anyway ... if its got a cat, then that's not a straight pipe - if what im reading is right: im gonna assume youve changed to a 3" piping all the way.. and thats your issue there... exhaust piping too big (bigger doesnt mean better in your situation), youve just created backpressure, and youve most likely lost some rpms in the lower end

[Squalled]

As Jeffy said, biggest you should run with stock internals is 2.5" since it's not too large for our cars. 3" is quite big and even a few cammed guys may not even run that size.

[rchut1]

4 hours ago, jeffy said:

having some doubts with your exhaust "specialist" mechanic.. because ive never heard of such a thing, but anyway ... if its got a cat, then that's not a straight pipe - if what im reading is right: im gonna assume youve changed to a 3" piping all the way.. and thats your issue there... exhaust piping too big (bigger doesnt mean better in your situation), youve just created backpressure, and youve most likely lost some rpms in the lower end

thanks for reply, I feel as yeah the car has lost power in the lower revs 100%! from what the mechanic showed me while the car was on ramps it that the pipe coming from the engine to the end of the car was fully replaced. looking on the invoice it shows yeah he has changed it to "3 piping do you think a lower size piping will increase performance again or will I need to replace the entire exhaust ?

[jeffy]

 

3 hours ago, rchut1 said:

do you think a lower size piping will increase performance again 

2.25"-2.5" would be more ideal for your setup

3 hours ago, rchut1 said:

will I need to replace the entire exhaust

it will pretty much be replacing most of the piping from the headers.

Quote

the pipe coming from the engine to the end of the car

Its probably a flex pipe (bendy pipe between headers and cat)

 

 

Image below shows an exhaust "system" - (full exhausts systems go from headers all the way to mufflers) (some systems only go from the catalytic converter to the muffler or - cat back systems for short)

 

 

 

sorry i think i misunderstood you initially.. the term " straight pipe " refers to literally a pipe going straight from headers(exhaust manifold in above diagram) to the muffler (some may not even have a muffler) .. the cat (catalytic converter) is there for emissions, and the muffler muffles the sound, resonators (not resignators) are also used to reduce drone.

[rchut1]

37 minutes ago, jeffy said:

 

2.25"-2.5" would be more ideal for your setup

it will pretty much be replacing most of the piping from the headers.

Its probably a flex pipe (bendy pipe between headers and cat)

 

 

Image below shows an exhaust "system" - (full exhausts systems go from headers all the way to mufflers) (some systems only go from the catalytic converter to the muffler or - cat back systems for short)

 

 

 

sorry i think i misunderstood you initially.. the term " straight pipe " refers to literally a pipe going straight from headers(exhaust manifold in above diagram) to the muffler (some may not even have a muffler) .. the cat (catalytic converter) is there for emissions, and the muffler muffles the sound, resonators (not resignators) are also used to reduce drone.

thank you so much for your info, ill be ordering a full new exhaust with a different pipe size. hopefully ill book in asap, hoping to get my original power back (fingers crossed)

[Squalled]

What section was changed at the front? Before the shouldn't be changed even when you port the headers. Going to 2.5" will be good if you are planning future mods. You'll find 2.25" is the slightly bigger than the standard piping and won't yield as much of a gain if you plan on modding more.

[RSA_Platinum]

On the topic of exhausts, is it worth it to pay more for a mandrel-bent cat-back system over a press bent one? Stainless steel or mild steel system? I've been quoted $650 for stainless steel mandrel-bent system vs 4380 for a press-bent one (in Perth).

Is the extra cost worth it?

[Squalled]

4 minutes ago, RSA_Platinum said:

On the topic of exhausts, is it worth it to pay more for a mandrel-bent cat-back system over a press bent one? Stainless steel or mild steel system? I've been quoted $650 for stainless steel mandrel-bent system vs 4380 for a press-bent one (in Perth).

Is the extra cost worth it?

That's fairly decent price. Most places in Sydney seem to charge about $100-$200 more for the same setup. What size piping are going for also? One of the common things I've found is stainless seems to sound a lot more raspy but stainless lasts a lot longer than mild steel too hence the price difference. Just make sure you get a big resonator or 2 small ones to remove the "buzz" unless you like it, all up to you.

[RSA_Platinum]

28 minutes ago, Squalled said:

That's fairly decent price. Most places in Sydney seem to charge about $100-$200 more for the same setup. What size piping are going for also? One of the common things I've found is stainless seems to sound a lot more raspy but stainless lasts a lot longer than mild steel too hence the price difference. Just make sure you get a big resonator or 2 small ones to remove the "buzz" unless you like it, all up to you.

I'm going for the 2.5-inch piping, I don't think I'm ever gonna modify this car enough to warrant anything bigger. I think I might actually ask for a bigger resonator to dampen the raspiness, but to be totally honest, I don't really know what particular sound I'm listening for that you'd call raspy. I just know what sounds I like and don't like 🙂 

If anyone has a vid showing a stereotypically raspy exhaust, I'm all ears (and eyes). I mainly going for stainless for the longevity of the material and weight savings.

[Squalled]

11 minutes ago, RSA_Platinum said:

I'm going for the 2.5-inch piping, I don't think I'm ever gonna modify this car enough to warrant anything bigger. I think I might actually ask for a bigger resonator to dampen the raspiness, but to be totally honest, I don't really know what particular sound I'm listening for that you'd call raspy. I just know what sounds I like and don't like 🙂 

If anyone has a vid showing a stereotypically raspy exhaust, I'm all ears (and eyes). I mainly going for stainless for the longevity of the material and weight savings.

Well 2.5" is the biggest you should go unless you're going cams and onward. The resonator will quieten the sounds and remove the rasp but, the muffler choice is also a big one. A lot of mufflers like cannon style will make it sounds like a bee hive.

Literally search up Honda exhausts on eBay, they sure love their "fart cans".

[RSA_Platinum]

11 minutes ago, Squalled said:

Well 2.5" is the biggest you should go unless you're going cams and onward. The resonator will quieten the sounds and remove the rasp but, the muffler choice is also a big one. A lot of mufflers like cannon style will make it sounds like a bee hive.

Literally search up Honda exhausts on eBay, they sure love their "fart cans".

Oh yeah, its a solid no to a cannon; I happen to like my ears being able to hear things. I'm gonna go for a regular straight-through oval muffler that hopefully isn't obnoxiously loud.

Oh damn, they sound quite bad. Definitely want to avoid that noise. 

[jeffy]

2 hours ago, RSA_Platinum said:

On the topic of exhausts, is it worth it to pay more for a mandrel-bent cat-back system over a press bent one? Stainless steel or mild steel system? I've been quoted $650 for stainless steel mandrel-bent system vs 4380 for a press-bent one (in Perth).

Is the extra cost worth it?

yes

 

stainless steel sounds better than mild...

also stainless steel is thicker than mild.. soo if lets say for example you hit something the chances of something piercing through stainless is less

also as for mandrel bends, think about a bendy straw vs a non bendy straw... what will happen when you try and bend the tubing in both situations ? how does the air flow when it comes to the bends ?

Quote

I'm gonna go for a regular straight-through oval muffler

thats going to have some rasps, look for something that has bends inside the muffler

https://au.toyotaownersclub.com/forums/topic/56527-exhaust-system/?tab=comments#comment-571438

 

Quote

 The resonator will quieten the sounds and remove the rasp 

Resonators only move the sound to to a different rev range (or change the sound reverb)  - volume will be same

[RSA_Platinum]

4 hours ago, jeffy said:

yes

 

stainless steel sounds better than mild...

also stainless steel is thicker than mild.. soo if lets say for example you hit something the chances of something piercing through stainless is less

also as for mandrel bends, think about a bendy straw vs a non bendy straw... what will happen when you try and bend the tubing in both situations ? how does the air flow when it comes to the bends ?

thats going to have some rasps, look for something that has bends inside the muffler

https://au.toyotaownersclub.com/forums/topic/56527-exhaust-system/?tab=comments#comment-571438

 

Resonators only move the sound to to a different rev range (or change the sound reverb)  - volume will be same

I thought the stainless was thinner due to you needing less material for corrosion resistance, hence why they’re more raspy.

With the muffler, do you mean something like a baffled system or one where the exhaust gas has to snake through the whole body of the muffler?

[jeffy]

23 hours ago, RSA_Platinum said:

I thought the stainless was thinner

my mistake you are correct, stainless steel is thinner, lighter and the materials made are stronger than mild steel.

 

23 hours ago, RSA_Platinum said:

snake through the whole body of the muffler

 

 

[Hiro]

On 8/3/2019 at 8:27 PM, jeffy said:

my mistake you are correct, stainless steel is thinner, lighter and the materials made are stronger than mild steel.

 

In general, mild steel is stronger than stainless steel.  Exhausts are usually 409 or 304-grade stainless steel, which has a yield strength of ~200MPa (normal mild-steel tube will be 250MPa)

[Squalled]

From memory, could be wrong, I remember hearing that stainless generally lasts longer as it won't rust as quickly as mild steel? Not sure on this but I have seen it happen after some time on mild steel systems.

[Hiro]

2 hours ago, Squalled said:

From memory, could be wrong, I remember hearing that stainless generally lasts longer as it won't rust as quickly as mild steel? Not sure on this but I have seen it happen after some time on mild steel systems.

Corrosion protection is the whole point of stainless.