mattXCoupe

hey guys,

i hope im not asking an all too common question here but here goes....

im gonna be needing a new set of extractors very soon on my coupe.... what can you all suggest? its already got a twin 2 1/4 exhaust which i was planning on keeping.... its a mildly worked 351C.. C4.. in an XC... 600 vs holley & edelbrock man.. if ya want more details just ask...

cheers
matt

xacoupe

are you planning more mods in the future??

STROKEXD

Either pacemakers or pacemakers... 4 into 1's unless you love towing then 4:2:1's. Go 1 5/8 primary pipes for your current combo.

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xacoupe

I would think 4 - 1 would not suit his combo .. it's a very torquey setup so I would think Tri Ys would be perfect .. unless he has future plans

STROKEXD

Yeah but I've come to find out through trial and error that there is more myth than fact with 4 into 1's not giving a good low end response compared to tri-y's.. The old rule of thumb is for revs go 4:1, for torque go tri-y's. I've found you won't get any less torque with 4:1's providing primary pipe diameter and length is suitable to the motor.

There's a few dyno comparsons out on the web with the same findings.

Personally I wouldn't use tri-y's again. No real gain in it.

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xacoupe

Basically you end up having a smallish pipe diameter to make up for the design, thereby removing the basic benefit of free er flowing at higher revs.
There are other considerations too ... tri ys are cheaper and more importantly, don't hang down as much. I got my pair for 50 bucks ( 2nd hand obviously ! ) and can't see the need to get more expensive 4-1

brenx

Nothing wrong with Tri-y's. XBWGN's 351 breathed out 212rwkw through 4-2-1's. It went extremly fast for a 2 tonne car. Espesially when you can buy 4-2-1's around the traps for $50-$150 secondhand. Money well spent I think.

My setup benifited with 4-1's. I had 180rwkw with tri-y's and 230rwkw with 4-1's. The 4-1's just suited my setup better.

Brenden

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XB Fairmont (street car) 11.07@123.02mph.

falcon coupe

Same here, i gained 16 rwkw changing from tri-y`s to 4 into 1`s.

STROKEXD

Yeah nothing wrong with Tri-y's, but not much right with them either in my view. On same motor I've had 2 different sets of tri-y's and 2 sets of 4 into 1's (different primary pipes). Never lost any bottom end response as I was told would happen. The 4 into 1's gave me gains in every area - except financial and ground clearance - two things not really an issue for me.

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XEesp351

Hi fellas, Dont forget that the Phase 3 had Tri-y's on them, cant have been too bad, i believe the reason was to try maintain a flatter torque curve, without killing top end. An article ive got written by the Phase 3 designer mentions they tried a set of extractors that dumped into 4 side by side collectors that was brilliant, but too hard to fit into the engine bay on production line. Ive seen these fitted to 5.0litre race engines too, wish i knew where to buy them.