****ing /thread

 

Well Johnny over yonder in Winchestertonfieldville made 780 with a stock TYPE R axle back so that means it is law that you don't need a Mack truck diesel stack hanging under your car to make power on a ls turbo. LOL.

But on a real note all you need is some 3" and some good mufflers and you will be happy with the sound and performance. IMO the only reason to run 4" on a honda is to get around a rule that you must have exhaust and muffler when you need/want to run open dp. Some guys on ls1tech.com run exhaust that big but they are actually making serious power.

 

What a single 4" exhaust? Can you link to said people and their thread/sig?

 

Point I was trying to make is Johnny Cash doesn't even know if it will lose power or not yet he is stating

What is this being based off of? His knowledge? I thought that was funny so I tried to bait him alittle but he didn't bite.

Anyways since there hasn't been a comparison on 3" vs 4" has anyone seen a comparison on 3" vs open downpipe?

I've seen a Cobra Mustang make 980rwhp on 2.5" exhaust. Hell I made 629rwhp on a Mustang Dyno through 1 5/8" longtubes and 2.5" exhaust. On the flip side my N/A 5.0 made 438rwhp with 1 3/4" longtubes and 2.5" exhaust, I did nothing but switch to 3" and it jumped to 456rwhp. If I could have gone with 1 7/8" longtubes I would have picked up even more. According to the other Mustang gurus 3" should have been way too big for my setup. Another thing is a bolt on LS1 will pick up power going to true dual 3" exhaust. Another one, a bolt on Mach 1 which is a little N/A 4.6L V8 will gain (alittle not much) going to big 1 3/4" longtubes over a 1 5/8" longtube. Now I know this doesn't have anything to do with Hondas but I know more about V8s than I ever will about Hondas probably. LOL

And BTW, yes 3" is exactly 1" smaller than 4". If anyone was still unsure about this.

 

It's because I don't fall for silly kid games. Nice try though youngblood.

 

I am good friends with the guy that bought Phil99vette's old Vette. He is running a pte88 turbo with a 4" exhaust all the way to the rear of the car and made low 700's on 9-11 psi. Most threads I see people do either twins with 3" dual or a big single turbo with 4". On a Honda a 4" is quite large for a street car that will actually be driven on the street on a regular basis.

 

Most single turbo v8 owners go with 4"-5" downpipe into a Y with dual 3" exhaust, myself included.

 

Exactly. I wonder what flows better for them, a single 4" or 5" or dual 3"?

 

Just calculate the cross-sectional area of the pipes and you will get a close number to their flow capability. If it's dual, then multiply by 2.

Dual 3" outflows a 4" single, although it depends on how the exhaust is merged/split. Turbulence plays a big role, and a lot of our smaller engines demand good velocity out of the exhaust. For most higher RPM engines, a big single exhaust always work better than duals of near equivalent flow rating.

Efficiency and bottle-necking are two important factors to determine exhaust size. To make efficient power, the engine runs cooler, requires less octane, and also needs less fuel. Running the engine at an efficient state means the setup should be nowhere near bottle-necking. Running lesser fuel also means there is also less heat and exhaust gases exiting the motor. This in turn, also stretches the power capability of a certain exhaust. Whenever the engine needs to run rich to combat higher EGT's, or needs to run more boost/much less timing and richer AFR's by a noticeable amount on a certain fuel, then it is a sign of needing a bigger exhaust.

A 3" system can support lots of power. I've seen cars making over 800 WHP with a 3" system, but it also requires race fuel much sooner than expected, and also very big turbos running lower boost. However, I can assure you that if you had a medium compression motor (9.5:1 - 10.0:1), medium frame turbo (35R or smaller) and making 500 WHP on pump 91oct on a Honda B18, that 3" exhaust is becoming an issue already.

The next factor that determine whether a big exhaust works well, is due to your turbine sizing. A turbo with a small turbine housing likes to have a big exhaust system or a big downpipe. A big turbine housing can cope with smaller downpipe or exhaust. It's no coincidence that a smaller A/R housing is building much higher exhaust pressures at the inlet, hence, sees a much greater improvement when it can reduce those pressures the moment the exhaust gases leave the turbo. For a bigger turbine wheel/housing, when the pressure differential between the inlet and the outlet is lower, thus doesn't require as free flowing downpipe/exhaust as a smaller turbine; yet both engines could be at identical HP/TQ. If your turbine is on the smaller end of the spectrum, you should give it more headroom in exhaust requirements.

If you are on the high HP pump gas game, go with 4", and find some way to make it quiet. I have an electronic muffler on mine, so it becomes quiet in a flick of a switch. It's not a dump or E-cut, so the car sounds awesome and I drive loud all the time until a cop cruises nearby or driving through residential neighbourhoods at late nights

 

Well its a stock LS head on log manifold making 500whp on 93 around ~25psi with a 62mm wheel. If it was a vtec head I probably wouldnt second guess going to 3".

 

If your planning on staying with 500whp there is no need for the 4 inch exhaust. I have a 3inch k teller with magnaflow muffler n like what a few said before it is quiet untill the WG opens.

 

Hey Tony the tiger, what is considered to be a small turbine housing? I would like to know more about your setup in your integra. I have seen your videos on youtube and it looks like it's very fun to drive!

 

You'll have to judge it by the turbo.

If you are on a GT35R for example, the power rating on that turbo is reaching the upper limits on a T3 turbine housing. A 0.63 a/r turbine housing on this turbo will considered a small housing.

 

Here is some pictures of the exhaust work I did on my car... I had a major loss in power on my car and found that the muffler on my single exhaust setup was shot... so when i removed the muffler my entire tune was destroyed... so I tried to put together an exhaust system that was high flow but also was properly muffled... With the extremely lean conditions added from taking off that screwed up exhaust, after adding this Y design it stayed exactly the same....

 

How bad does that resonate into the car? Usually when the exuats doesnt end outside of the frame or the car its resonates pretty bad inside the car but outside could be quieter.

Lightning what size turbine housing are you running and what exhaust wheel?

Great write up Tony learned alot from that thank you very much

 

Tony your are the man and are crazy lol

Yeah the muffler isnt quite as far as it was before which I think is the main problem. Im goin to try and exit it past the bumper today by adding a little more pipe.

Its an SC61 turbine wheel in a T3 .63 A/R.

 

LOL. We have very similar license plates! I wonder how that dual exhaust sounds? Nice work man!

 

Specifically a P-trim exhaust wheel in the .63A/R IIRC. Not a whole lot of backpressure created in that case. Lighteningteg, am I correct on this? Please remind me. was it a 6169,or 6176?

 

Can you explain this back pressure thing? How does that effect absolute power output?

 

it does resonate in the cab pretty bad so i will be routing piping over the top of the control arms in the near future... im thinking about adding these 100 cell high flow mil.spec cats (reese tuning evo Time Attack car made 689whp with this cat) as well if the interior resonance does not decrease after rerouting the exhaust over the control arm...

its a properly functioning dual exhaust though...

Tony the Tiger is a genious BTW

 

6152e

 

My buddy who has a 700+hp integra went from a 3inch down pipe and exhaust to a 4 inch aluminum dp and exhaust but it dumps right behind the doors in the middle of the car. He said he should see around 50whp gain from it.

 

Ok. Pete did yours specifically. I didn't remember. I'll PM you the "backpressure thing", when I get an opportunity today.

 

Well I added about 4" of pipe to the end of the exhaust and it is much bueno.

 

Went from a full mandrell 3" DP and ex with magnaflow "race muffler" to 4" DP "race muffler" and 4" aluminum ex that stopped under the rear seat. car makes 750 WHP 575tq and the exhuast made a difference of about 40 WHP (but more tq) over the 3. Under 700 theres no way you NEED 4"... In the LEAST