The muffler in the 3 Atr will be the choke point before the 3 downpipe.i only saw a gain with the 3.5 downpipe by removing the muffler and going to a 3.5 inch single exhaust.the car leaned down .4 on the wideband and was much more responsive in racing.this was on a very fast buick and I don't think most need more than a 3 inch setup especially if you have a 3 th fp and a nice 3atr crossflow setup which has a sweet sound to it.any gain moving from a THDP (3") to a TA Performance 3.5" External Gate down pipe??
250 CU Stroker Motor
GN-1 Heads
E85
TA SS/Race Headers & 46MM Gate
6870 3 Bolt DBB Turbo
Pypes 2-1/2 inch exhaust --soon to be replaced with ATR 3" SS Crossflow
The general of thought is mid / high 9's is the transition area for going 3.5 over 3. Doesnt gain anything before that. Mid 9's and faster for sure.any gain moving from a THDP (3") to a TA Performance 3.5" External Gate down pipe??
250 CU Stroker Motor
GN-1 Heads
E85
TA SS/Race Headers & 46MM Gate
6870 3 Bolt DBB Turbo
Pypes 2-1/2 inch exhaust --soon to be replaced with ATR 3" SS Crossflow
None. 3.5" single will get you mid 9's so to argue that 2.5 vs 3 in a dual system shows any benefit is moot. Either will work just fine.How much of a difference is there from a performance stand point between a 2.5" duals and a 3" duals (or even a 3" single for the matter)?
Are we talking a tenth?, several tenths?, half a second?
But a 2.5 dual weighs 40 lbs more.unless the cars running in the 9s a single 3 inch is fineThe 3" crossflow system flows less than a 2.5" dual. 9s is where I would want a 3.5" downpipe.
There is a difference between out flowing and what the engine is actually pushing thru it. I dont think even an 8 sec engine would out flow a dual 3 like the GN1. I run a 4" single modified to accept the 22" long Borla XR-1 Race muffler. I'll never out flow it and my car makes around 800fwhp.Wouldn't two 2.5" mufflers out flow the single 3" or 2.5" pipe feeding them? I get the reasoning on the reducers though.
I only had the last car at the track once - couldn't get it to hook but went still went 10.80 @ 128 through a Hooker 2.5" cat-back being fed by a 3" downpipe.
Wouldn't that be 30% increase?The main benefit of going single is weight. (and balance since the entire system is on the passenger side)
Just to throw some math at you, the cross sectional flow area of a 3" pipe is 7 square inches. The flow area of two 2.5" pipes are 9.8 square inches. It's only a 20% increase in flow area but it comes with a lot more weight and a lot more friction area from the extra walls and bends.
More math... a 10' section of 3" pipe has 7.85 square feet of wall area, 20 feet of 2.5" pipe has 13 square feet (and twice the bends).
So basically 3X the friction area with 20% more flow area. In real world numbers the extra flow area won't do anything unless the 2.5 system is a cork. So any normal street car probably won't see a HP increase worth the cost.
BUT every car, no matter the power level, will see a performance advantage with less weight.
My personal GN has a SS 3" single shot with a Dynamax Race Magnum. I've got a pretty hot roller 4.1 and there's nothing to gain from opening the dump (except noise and turbo whistle). One of these days I'll toss the muffler. It didn't quiet the car down any but it killed off a lot of whistle at cruise.
Not yet but closeso whats the flow on the atr crossflow system? I have been in the nines @ 29 psi with a 67 turbo? My current best 1/8 is a 6.28 @ 112 mph @ 27 psi
Am i at the limit of what it can flow?
The downpipe is ATR 3 INCH