Whats In My Back Boxes, Suggestions Please?

[conaero]

You could always just weld the valve open, even easier.

 

[GG]

Whats in the x-cross section, whats its function, does it allow the gases to cross from one pipe to the other?

 

[stradaman]

Anyone heard of these people? There stuff looks good.

http://www.prindiville.co.uk/storefront/maserati-1/4200-gt/4200-gt-exhausts/

Andy.

 

[jason23tong]

Its a 2004 QP. Also shaved 1kg off the weight of each box

 

[jason23tong]

Was thinking of doing that but that would still have meant a slight restriction on the main high flow pipe from the valve plate and mechanism.

 

[jason23tong]

You could always just weld the valve open, even easier.

Was thinking of doing that but that would still have meant a slight restriction on the main high flow pipe from the valve plate and mechanism.

 

[jason23tong]

Great pics and thread!

Did you leave the fiberglass wadding out when you reassembled?

GG.

I put the fiberglass back. I noticed the perforations on the wall facing the engine and figured the fiberglass was there to dampen the sound. I didn't want tin can sounding exhaust.

 

[jason23tong]

Whats in the x-cross section, whats its function, does it allow the gases to cross from one pipe to the other?

Its like the Larini X-pipe. It removes the center resonator.

 

[jason23tong]

Whats in the x-cross section, whats its function, does it allow the gases to cross from one pipe to the other?

Here is a picture of my X-pipe. its painted to make it look like an original part of the exhaust system.

 

[drellis]

i thought that putting straight pipes on a n/a engine normally reduced power slightly ? turbo cars work best with no bak pressure though

 

[stradaman]

Turbos need a bit of pressure, to help post manifold pressure.
Those cross pipes, will lose power on any engine. Air does not like changing direction, or having any obstruction.

Andy

 

[GG]

Some back pressure is important, I have a open 4 into 1 on my drag bike (275bhp), if you run it for more a very short while, the valves will burn out pronto.

So what is the x pipe for exactly?

 

[stradaman]

Valves burn out, because of temp, lubrication, and poor combustion. Nothing to do with back pressure. Back pressure will interfere with cylinder scavenging. Too much, and cylinders fill up, and the new charge is ruined!

Andy.

 

[GG]

Ok.

SO whats the X-PIPE FOR?

 

[Emtee]

Ok.

SO whats the X-PIPE FOR?

GG, it's lighter than the stock centre section and there's a nominal improvement in performance, but the main purpose is aural. It's a lot louder than the standard muffled centre section. The X pipe is very loud and the H pipe slightly less so, but both are louder than stock. Between these, the back boxes and the sports cats you can tune the exhaust system to whatever dB level you think your neighbours will stand.

 

[stradaman]

Ok.

SO whats the X-PIPE FOR?

Cosmetic loudness! Crisscrossing gas flow, just will not only slow gas speed down, but increase back pressure, where you don't want it. Much better, to have straight through pipes, or for quietness, race type silencers, that can be quietened, to what DCB, you desire.

Andy.

 

[GG]

Ok, some good info there.

Took off the boxes today in a moment of boredom. Using the images on this thread I cut open the box. I could not reach the flap so need to find an English speaking person with a blow-torch in old east Germany to cut them off!

Should be interesting, the flap is very restrictive.

 

[Emtee]

Cosmetic loudness! Crisscrossing gas flow, just will not only slow gas speed down, but increase back pressure, where you don't want it. Much better, to have straight through pipes, or for quietness, race type silencers, that can be quietened, to what DCB, you desire.

Andy.

But surely the cats (whether after-market sports or 20th century stocks) are the primary source of back pressure? Whether the centre pipes cross or not (in whatever configuration) down the line is neither here nor there in the scheme of things?

 

[GG]

I just dont get the x-pipe thing. How loud would it be without it?

 

[mjheathcote]

Cosmetic loudness! Crisscrossing gas flow, just will not only slow gas speed down, but increase back pressure, where you don't want it. Much better, to have straight through pipes, or for quietness, race type silencers, that can be quietened, to what DCB, you desire.

Andy.

Not too sure.
Most V8's have an H pipe, my Triumph Stag has an H pipe, and that's fast approaching 40 years old.
The H pipe is there, I believe, to make the exhaust sound nice. It offers no restriction to gas flow.
The X pipe achieves the same result, however it was discovered that crossing the gas flow (unlike the H) has a performance advantage over the H due to exhaust pulses/savaging effect.
So the X does not slow gas speed down, nor increase back pressure, or the H would still be used.
Cheers