Anyone running a Tri-Y exhaust manifold?

Cutz · Post by **Cutz** » Sun Dec 07, 2014 12:43 am

RattyMcClelland wrote:About a 25 bhp increase at the vtec crossover and so much more open at the top end. It's so free flowing I see a proper 6psi in vtec where other usually see 7psi on supercharged ludes.

Mines a hytech long tube tri y.

Also the noise is.....epic using a tri y.

Sounds awesome, how about bottom end?

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Sun Dec 07, 2014 10:11 am

RattyMcClelland wrote:It's so free flowing I see a proper 6psi in vtec where other usually see 7psi on supercharged ludes.

ok, this has me confused... 6/7psi where?

mercutio · Post by **mercutio** » Sun Dec 07, 2014 10:29 am

at the intake he is saying the manifold flows so well it reduces back pressure at the intake I think

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Sun Dec 07, 2014 10:37 am

That's what I was thinking, but that doesn't make sense...
The intake manifold never 'sees' the exhaust manifold because whenever an inlet valve is open, the corresponding exhaust valve should always be closed.
All the intake manifold ever sees is the closed inlet valves or the cylinder/closed exhaust valve.
The only way the exhaust manifold would be seen by the intake manifold is if the exhaust valve was leaking by..?

Hence my confusion...

mercutio · Post by **mercutio** » Sun Dec 07, 2014 10:41 am

yeah or if there is some overlap possibly in vtec some race engines run overlap to help with cylinder filling/scavenging

Therealjj91 · Post by **Therealjj91** » Sun Dec 07, 2014 2:40 pm

Does anyone know how these compare to a fujitsubo mani?

damon · Post by **damon** » Sun Dec 07, 2014 3:10 pm

I got mine from h tune for a good price, not sure if the deal is still on. Havnt had time to fit it yet

Post by **RattyMcClelland** » Sun Dec 07, 2014 3:29 pm

IIncreasing exhaust flow reduces back pressure. Back pressure builds up to the intake manifold.
The tri y exhaust is so much more open in vtec especially where there is valve overlap this mean pressure in the chargers manifold Is reduced.

Before vtec I'm at a peak of 9psi. At the crossover pressure drops to 6.3psi due to more open valves cam.

I did loose some bottom end torque. This was all untunned but I was at 227bhp and 156lb ft before positive displacent pump action.

Therealjj91 · Post by **Therealjj91** » Sun Dec 07, 2014 3:44 pm

So all in all its a better manifold then the fujitsubo? What size is the collector on the Tri-Y?

damon · Post by **damon** » Sun Dec 07, 2014 4:03 pm

Think the collector is 2.5inch, sure that's what it said lol