Help Moving Restriction From Rear Cannon!

[Harey]

looking at the graph, i'd say that only a small percentage of the difference in pressure is due to restriction in the intercooler. the reason being that as airflow increases both the before and after pressure decreases at roughly the same rate. if it was a restriction the pressure before the turbo should increase while the pressure after it should decrease reletive to each other. you have to remember that the pressure after the intercooler will always be less than before the intercooler due to cooler air being more dense. depending on your before and after temps this could account for up to 10% of the drop you are seeing, and would defininately account for between 5 to 7% of the drop.

oh and FYI, the stock setup actually runs the wastegate off the cold pipe. when i put my fmic on i cut the stock nipple off and welded it onto the hot pipe. this made it hold boost much more stable. was getting spiking with it running off the bov line.

"if it was a restriction the pressure before the turbo should increase while the pressure after it should decrease reletive to each other"

That doesnt make any sense.

If what you mean is that you expect the pressure after the intercooler to drop as the airflow increases then yes marginally by not this much. You mention numbers like 7% and 10%. The pressure drop up to 4,000rpm is only 2psi but increases to almost 5psi in the top end. That is a lot more than 7 or 10%.

Intercoolers normally have a rating of less than 1psi drop at 15psi etc.

Not to mention Trent was the one who was telling me that the shapes should be similar if the intercooler is flowing well.

The stock configuration on my R34 GTT definitely gets the pressure signal from the hot pipe (turbo to the intercooler).

[Harey]

Doesnt the factory WG run off the intake pipe? I cant remember but mine is connected to the inlet manifold now..u think would it be any better off the hot pipe?

yeah i think a new muffler would be an eaiser way to go about it..I looked at mine today and thought stuff that

The factory wastegate runs off a nipple on the hot pipe, well it does on my R34 anyway. The intake pipe has 2 connections, a bov return and a breather hose from the pcv. Not to mention there isnt pressure in the intake pipe, only a possibility of vacuum.

If the exhaust is too loud or it is too hard then I will look at a new muffler but I cant see why it cant be done nor am I satisfied with how it is currently.

[boostn0199]

Mate what i used is the die grinder so that should get you out of trouble. Its a dog of a job but to make it easier once you penetrate one part use a chisel to break the rest Of the welds.

[SiR_RB]

im realy interested in the new kakimoto full mega N1+rev, wonder if this has this restrictor in it aswell, because it complies with the 93db JASMA rating hmmm

[mad082]

"if it was a restriction the pressure before the turbo should increase while the pressure after it should decrease reletive to each other"

That doesnt make any sense.

If what you mean is that you expect the pressure after the intercooler to drop as the airflow increases then yes marginally by not this much. You mention numbers like 7% and 10%. The pressure drop up to 4,000rpm is only 2psi but increases to almost 5psi in the top end. That is a lot more than 7 or 10%.

Intercoolers normally have a rating of less than 1psi drop at 15psi etc.

Not to mention Trent was the one who was telling me that the shapes should be similar if the intercooler is flowing well.

The stock configuration on my R34 GTT definitely gets the pressure signal from the hot pipe (turbo to the intercooler).

and you are running 33% more boost than 15psi, and i would hazard a guess that the restriction they have is not linear, but exponential. so factor in, lets say for arguments sake, 1.5psi of pressure drop simply from the drop in temperature, and about 1.5psi of drop from normal restriction of a decent flowing intercooler, at high rpm you are only losing around 1% of flow from your intercooler.

my point is, i can pretty much garantee that you won't see all of that near 5psi drop magically disappear with a new intercooler. my guess is that you will still have about 3psi of difference.

as for what i said about the wastegate taking the reading from the cold pipe, that is true for the r33. i wasn't aware that the r34 is different.

[mad082]

as for the initial post about how to remove the restriction from the exhaust, just simply cut cannon off and put a new one on with a 3" ID baffle pipe. it will probably be noticably quieter than what the fujitsubo one will be with the restrictor removed (since in the thread you linked to the guy said that it made his car noticably louder) and still flow just as well.

[boostn0199]

im realy interested in the new kakimoto full mega N1+rev, wonder if this has this restrictor in it aswell, because it complies with the 93db JASMA rating hmmm

What i personally think is whenever they mention jasma approved means they just stick a restrictor in to make it approved. Instead of actually putting decent muflers they take the short cut as many ppl will never know and be happy with the appearance of the exhust from outside and happy with the sound so will never investigate further.

[chiksluvit]

im realy interested in the new kakimoto full mega N1+rev, wonder if this has this restrictor in it aswell, because it complies with the 93db JASMA rating hmmm

Yes it does

had that before and its quieter than regu06R

the new N1+rev was the first exhaust which made me aware of the restrictor

[eron]

Nope exhausts after turbos are different. Bigger is better everywhere in the rev range. Better flowing exhaust only has the potential to reduce lag.

Whats the point in a 3" exhaust when it reduces to 2.5" in one location, might as well have a 2.5" exhaust.

http://www.team-integra.net/forum/blogs/michaeldelaney/103-advanced-exhaust-tech-ii-backpressure-area.html

So you are saying that putting a 5" exhaust is better?

From my limited experience and knowledge, it's about velocity of the exhaust exiting. Blow on a thin straw using X amount of force vs a thick pipe. Which one has gas escaping faster? Then blow 10 times harder, and the thick pipe will flow better.

2.5" at the end of the exhaust is definitely different from having it in the middle or upfront.

In the end, it depends on how much power the car is making, and where in the range the power is wanted.

[tridentt150v]

Why don't you use a set of cobalt drills and just cheese it and see if that makes a difference? Buy a 10-15mm bit and say a 5mm bit. Use the 5 as a starter and then finish with the bigger one.

Otherwise stones/tungsten carbide bits in a diegrinder tool or drill will do it if your patient. The other method is a hole saw, but it would have to be a good qual one for s/s and a big one, say 4" and good luck holding that [it can be done but will be a bitch to control].

[Harey]

http://www.team-integra.net/forum/blogs/michaeldelaney/103-advanced-exhaust-tech-ii-backpressure-area.html

So you are saying that putting a 5" exhaust is better?

Yes a 5" exhaust would be better. Sure you would not see much of a gain at the power level we are talking about, but you would not see any negatives apart from trying to fit the bastard somewhere!

You are getting mixed up with N/A cars like the integras in the link you posted. There is an article on the garrett site confirming this that bigger is better after the turbo.

[Harey]

and you are running 33% more boost than 15psi, and i would hazard a guess that the restriction they have is not linear, but exponential. so factor in, lets say for arguments sake, 1.5psi of pressure drop simply from the drop in temperature, and about 1.5psi of drop from normal restriction of a decent flowing intercooler, at high rpm you are only losing around 1% of flow from your intercooler.

my point is, i can pretty much garantee that you won't see all of that near 5psi drop magically disappear with a new intercooler. my guess is that you will still have about 3psi of difference.

Yeah I realise I wont defy physics and get the full 5psi pressure drop back. I am hoping with a better intercooler the after intercooler shape will be the same and at most be 2.5psi pressure drop in the top end.

The history with this intercooler is that I have never been able to run more than 15.5psi above 6,500rpm no matter what I do. That is with 2 different turbos, the other turbo was much larger and was proven to run 20+psi above 6,500rpm on other rb25dets. So I believe this test proves that at the very least that the intercooler is at least quite restrictive at higher airflow levels.

[simpletool]

+1 for 5" exhaust would be better.

For a turbo car the turbine and housing create back pressure for the exhaust valves. However a huge exhaust like 5" means the idle and response below 2000rpm would be a bit different.

[tridentt150v]

Anyway modifying your exhaust restriction is the first thing you should do for any setup. And for yours Harey it the next step before you can consider any other mod that would normally yield or unleash more kw. ie there is no use doing other mods if your exhaust restriction is the defining feature. So IMO its a no brainer, the only question you have to ask is grind vs replace?

[ARTZ]

i say replace with a budget cannon off fleabay..keep this one to clear noise defects should you get any..

Or just buy a good quality 3 inch muffler and never have a problem

[eron]

Yes a 5" exhaust would be better. Sure you would not see much of a gain at the power level we are talking about, but you would not see any negatives apart from trying to fit the bastard somewhere!

You are getting mixed up with N/A cars like the integras in the link you posted. There is an article on the garrett site confirming this that bigger is better after the turbo.

Bigger is better for peak power, and creating more noise. I would appreciate it if you can show me the article that says bigger is better for all rpms.

The link I posted earlier does include tests on turbo cars as well.

http://www.team-integra.net/forum/blogs/surferx/25-exhaust-basics.html

http://www.team-integra.net/forum/blogs/michaeldelaney/26-advanced-exhaust-tech-i.html

http://www.team-integra.net/forum/blogs/michaeldelaney/103-advanced-exhaust-tech-ii-backpressure-area.html

Edited June 27, 2011 by eron

[Harey]

Bigger is better for peak power. I would appreciate it if you can show me the article that says bigger is better for all rpms.

Here it is:

http://www.teamswift.net/viewtopic.php?f=2&t=7628&view=next

[Harey]

Anyway modifying your exhaust restriction is the first thing you should do for any setup. And for yours Harey it the next step before you can consider any other mod that would normally yield or unleash more kw. ie there is no use doing other mods if your exhaust restriction is the defining feature. So IMO its a no brainer, the only question you have to ask is grind vs replace?

Agree! I dont see the harm in grinding first, seeing if its acceptable noise wise etc. Then if not I purchase another muffler.

[eron]

Here it is:

http://www.teamswift.net/viewtopic.php?f=2&t=7628&view=next

Thank you.

This is from the article:

As for 2.5" vs. 3.0", the "best" turboback exhaust depends on the amount of flow, or horsepower. At 250 hp, 2.5" is fine. Going to 3" at this power level won't get you much, if anything, other than a louder exhaust note. 300 hp and you're definitely suboptimal with 2.5". For 400-450 hp, even 3" is on the small side.â€

[Harey]

Thank you.

This is from the article:

Yes exactly, going bigger then required wont net you any gains but it wont loose anything.

These are the 2 paragraphs before your sentence:

"Downstream of the turbine (aka the turboback exhaust), you want the least backpressure possible. No ifs, ands, or buts. Stick a Hoover on the tailpipe if you can. The general rule of "larger is better" (to the point of diminishing returns) of turboback exhausts is valid. Here, the idea is to minimize the pressure downstream of the turbine in order to make the most effective use of the pressure that is being generated upstream of the turbine. Remember, a turbine operates via a pressure ratio. For a given turbine inlet pressure, you will get the highest pressure ratio across the turbine when you have the lowest possible discharge pressure. This means the turbine is able to do the most amount of work possible (i.e. drive the compressor and make boost) with the available inlet pressure.

Again, less pressure downstream of the turbine is goodness. This approach minimizes the time-to-boost (maximizes boost response) and will improve engine VE throughout the rev range."

Not sure how it could be stated any clearer than that?? If you want to discuss this further please create your own thread.