how 'd you guys go about fitting the 3inch system through the rear crossmember hole did you have to get an engineer to drill it out so it fits the 3inches straight through

take the rear crossmember down to your favourite exhaust place, get them to enlarge the hole & fit a piece of 3 1/2" pipe in it's place & voila, nice big hole to fit a 3" exhaust thru

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Vaughan
'70 P130 Super 6
Fiesta XR4 (modified)
Formally: 510 L22B twin webber terror
510 FJ20et (510 FJ)

do u really have to fit a 3.5 inch pipe after u cut it? cant u just cut it and leave it as is?

also has anyone slotted the rear crossmember (for camber adjustment) whilst the crossmember is on the car? i was just thinking about drilling another hole just above the existing one and mounting it there (also it wont slip after time)

Well since you are cutting the crossmember and potentially reducing its strength a great deal, its probably very wise to weld back in a circular section around the hole you have ox'ied out to maintain some strength, plus it makes it less noticeable to a engineer.

im pretty sure maddat do a pre-fabbed one too

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Dan

I got a modified Xmember for 3" exhaust in Canberra $100

Okay, I have to ask this...

What f*cking engine are you putting in that needs a 3" exhaust system so much???

Exhaust flow is like inlet, bigger isn't always better. It is to do with flow dynamics (Positive and Negative pressures, Harmonics, Turbulent and Laminar Flow, Temperatures, etc). Do you understand enough about random theories and the chaos theory to know for sure that 3" is the best option for maximum area under the power curve???

_________________
http://www.capitalsteering.com.au - Steering you in the right direction
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I found someting on the net about enlarging it urself a while ago, ill try n remember what he did ok

weld a flat piece of steel about 1" wide n 1/4" thick across the center of the hole

mark the centre and dent with centre punch

drill a pilot hole through the centre

get a holesaw bit 3.5" diameter and drill through the crossmember

** I havnt done any of this **

when u now have a 3.5 inch hole through it

cut a apropriate length or 3.5 pipe and weld it in

this should now safely fit a 3" pipe

clean, paint vola


sounds so easy...not!

DAZDA,

Thankfully for turbocharged engines bigger is always better.
That being said, by the time you get to the rear x-member, the exhaust gases have most likely cooled (and therefore occupy less space) such that a 2.5" pipe will flow them just fine.
Regards,

Dave

_________________
USA Daily: 2014 Nissan GT-R, very minor modifications for the track
USA Project: 1978 280Z, minor suspension upgrades, VK56DE conversion in progress. SOLD
AUS Race Car: 1973 240Z, L28ET, Autronic, GT35R. SOLD
AUS Project: 1972 1600, 3200km old S15 SR20DET, ground up rebuild. SOLD

Dave,

It is all good, I know. This was my point.

Does this guy really need a 3" exhaust system through the crossmember?

You are correct in saying that the lower the pressure on the output side of the turbine wheel of the turbo, the more efficient it is at spinning the compressor (in theory). You know as well as I do though, that you can get better gains by fixing the exhaust system flow at the turbo end rather that just putting on a 'bigger pipe'. Getting better flow out of the turbo for the waste gate, turbine, etc, will help more than whether you have 3" rather than a 2.5" pipe through the crossmember (especially when there is normally a muffler of some sort immediately after the crossmember!). And as you have also pointed out, like I did, temperatures come into consideration when working out flow. The gas is a fair bit hotter straight out of the turbo than it is at the crossmember.

_________________
http://www.capitalsteering.com.au - Steering you in the right direction
http://www.fifthgear.com.au - Get the Driver's Edge

DAZDA,

I completely agree. Is there any real need for a 3" exhaust at the cross-member: no. For the reasons we have agreed on.

Also as you say, getting the dump-pipe (that being the exhaust directly off the back of the turbo - not for you DAZDA but for anyone else who is curious) as big as possible is of much greater benefit: as this is where the gases are at their hottest and therefore require the most space.

That being said, is the standard hole big enough for a 2.5" exhaust?

Regards,

Dave

_________________
USA Daily: 2014 Nissan GT-R, very minor modifications for the track
USA Project: 1978 280Z, minor suspension upgrades, VK56DE conversion in progress. SOLD
AUS Race Car: 1973 240Z, L28ET, Autronic, GT35R. SOLD
AUS Project: 1972 1600, 3200km old S15 SR20DET, ground up rebuild. SOLD

No. the biggest pipe you'll get thru a standard x-member is 2 1/4" & even then it's a snug fit. Mind you even a 2" is better than the standard 1" drinking straw.

_________________
Vaughan
'70 P130 Super 6
Fiesta XR4 (modified)
Formally: 510 L22B twin webber terror
510 FJ20et (510 FJ)

Ive just put in an sr20 turbo and i was told i would need a three inch pipe obvisouly you dont think it necessarynear the crossmember so what would you recemend then?

Ive just put in an sr20 turbo and i was told i would need a three inch pipe obvisouly you dont think it necessarynear the crossmember so what would you recemend then?

Blackdat,

Clearly I don't know the specifics of your setup, but if you are going to run a 3" dump pipe off the turbo then you should probably run a 3" system for the rest of the exhaust. Which will require you to put a bigger hole in the crossmember. Just make sure you do as Godzilladat said and weld back into the crossmember a 3 1/2" circular section to maintain the strength.

_________________
http://www.capitalsteering.com.au - Steering you in the right direction
http://www.fifthgear.com.au - Get the Driver's Edge