What Size Dumppipe For 500Hp

[nick81xd]

Tried searching but must be hopeless at using it. Also the 25 thread is full of small turbo results.

Have a 25 with a 3582r plain wheel turbo.

I have a full 3 inch turbo back exhaust with a resonator and rear cannon on it but I'm struggling with small amount of exhaust backpressure pushing open gate under full noise.

I am thinking the dump pipe might be a tad small With the wastegate plumbed back in. I'm aiming for 500+ (currently at 471hp).

looking at what people's opinions/experirence are on What size exhaust they have.

I have enough room for 4 inch but don't want to go oversized if not necessary.

Go with posts.

[scotty nm35]

A free flowing exhaust would just make it worse I think. You need to increase the wastegate actuator spring tension to help hold the manifold pressure in.

What is your base (minimum) actuator pressure?

[XRATED]

4" = no restriction.

Saying that, plenty of people have made 500bhp on a proper 3" exhaust with open screamers.

Personally I'd go with a 3.5" dump to tip, magnafolw muffler and a free flowing rear can of choice... Here's the thing though, make the waste-gate dump pipe larger and longer than you might think. Run it right down and merge it just before the cat in a nice long, shallow angle transition.

[nick81xd]

i have 14psi actuator springs in. its a turbosmart 50mm gate.

I cant stand the sound of a screamer pipe so plumbback is a MUST..
the gate pipe is about 60cm long joining in just before the cat area so i think having a bigger diameter exhaust in a copy of current setup will do the trick.

I just dont want to go to hassle of doing 3.5inch only to need a 4 inch down the track

[GTScotT]

There is no oversize with a dump pipe imho. 4" will work fine.

However I don't think that's your issue, you should be able to get away with a 3". Have you tried a heavier WG spring as mentioned above?

[XRATED]

4" is too loud if you already don't like the sound of a screamer.....

[nick81xd]

There is no oversize with a dump pipe imho. 4" will work fine.

However I don't think that's your issue, you should be able to get away with a 3". Have you tried a heavier WG spring as mentioned above?

i have changed the way the gate signal is being sent and it helped sort of. its either 16psi base and wont bleed past 21psi as a single connection onto wastegate or as a 2 port connection its 23psi minimum bleeding up to the 26psi wanted.

I would like to run 18psi low and 26psi high settings so changing the spring pressure up closer to higher settings is something im trying to avoid

[scotty nm35]

Then you must live with the boost drop I think, what rear housing are you running?

[nick81xd]

.82 rear housing.
Ported head with tomei poncams in it.

Ive got a feeling your right

[abr33]

I have 480hp on 3 inch, with cat, plumbed in gate, and with a 7 pound spring. Greddy gate holds very well though

[scotty nm35]

At what boost? 7psi is fark all spring...

I am running 26psi of spring, and after a few track days the tension has dropped back, now it only runs 19 psi off the spring. If you plumb pressure onto the top of the gate also you should be ok either way, mine easily runs a flat 32psi now with the 5 port Mac.

[Ke55pig]

I've got 3" dump making 310 was thinkin of upgrading the dump to 3.5 or 4 starting to seup up yo make 300-400 rwkw

[scotty nm35]

I have a 3 inch dump, and 2 inch off the 45mm gate. As long as they flow well and merge gradually into a 3.5 inch free flowing system you should crack 400kw with it fairly easily. Mine would be making that if I had a manual box...

[abr33]

At what boost? 7psi is fark all spring...

I am running 26psi of spring, and after a few track days the tension has dropped back, now it only runs 19 psi off the spring. If you plumb pressure onto the top of the gate also you should be ok either way, mine easily runs a flat 32psi now with the 5 port Mac.

22 psi, barely falls over any more than half a pound at 7700. Im running e-boost and pressure to both sides of gate respectively

Edited May 21, 2013 by abr33

[scotty nm35]

Sounds like a well sorted setup then. Pressure to the top is the key...

[hypergear]

I've made 431rwkws on 3 inch pipe externally gated. I wanted to run 4 inch how ever I can't get that size pipe to fit. I think biggest that fits is 3.5 inches.

[nick81xd]

Is that no fit in a r32 with a 25 in it stao? What fouled?.

I want to run plumbed in no matter what so can't include screamer. I prefer to hear the engine while its making noises not finding out after when its brokent

Edited May 22, 2013 by nick81xd

[34GeeTeeTee]

Is that no fit in a r32 with a 25 in it stao? What fouled?.

I want to run plumbed in no matter what so can't include screamer. I prefer to hear the engine while its making noises not finding out after when its brokent

It shouldn't make noises

Kurtis ran 500hp with the gate plumbed back and 3inch system....

Mine is a screamer so results are irrelevant I guess.

[nick81xd]

I mean in theory if a parts fails on boost can minimize the damage by hearing it go rather then all screamer noise

[nick81xd]

Decided ill go 4 inch dump just incase down track I get serious and go. Large frame turbo