Location: sunny coast, qld
Registered: October 2002
1jz exhaust manifolds
Thu, 04 November 2004 04:11
Hi,
just found this design used on a salt lake racer. He says that it pulls strong to 7000rpm now and it hits 145mph. Makes sense I think because longer runners means more top end. Has now done 204mph with single turbo. Any way, just thought some people may be interested
Longer runners promote quicker air velocities which increase lower end power. AFAIK shorter runners are better for top end, not sure why but may have something to do with flow restrictions with long runners. The ultimate example of this was the Mazda 26B race car which had intake runners on a slide system which would retract to make the runner length shorter as the engine rpm increased. Im not sure how they were actuated perhaps manifold vaccum?
Location: I wanna go Hawaiiiiii.......
Registered: November 2003
Re: 1jz exhaust manifolds
Thu, 04 November 2004 05:20
Actually NARROW runners promote exhaust velocity not long ones.
Long runners only promote exhaust cooling, which results in slow exhaust speeds.
Every degree of temperature that can be retained in the exhaust side of a turbo set up = Horsepower. This includes the dump pipe side of the turbo requiring either high temps and or high volume to maintain velocity and efficiency.
In the case of the salt racer HIGH mount turbo manifolds like that are designed for efficiency in space not performance.
Location: I wanna go Hawaiiiiii.......
Registered: November 2003
Re: 1jz exhaust manifolds
Thu, 04 November 2004 05:23
The science of tuned or adjustable length runners usually applies to NA applications and refers to the intake side not the exhaust maniflds of FI engines.
Thu, 04 November 2004 04:11
