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Re: Cracked Exhaust Manifold[240-260/85] posted by Philip Bradley on
Thursday, 7 May 1998, at 7:00 a.m.
I was the first guy in the country to do one of the late manifold conversions, back in 1990, when they first came out. After reading that the new manifolds added 10 hp, I bought one new from Volvo for $240, since I needed a rebuilt head and it all had to come apart anyway. Mine has well over 100,000 miles on it now. You only want an 1990 or later manifold. A 1989 or earlier 700 Turbo manifold is no better than a 240 manifold. I do not know about the 1993 and later manifold. I suspect it is just a 1990 one opened up for a Garret turbo. The opening for the turbo is different depending on what turbo the manifold was to be equipped with. Obviously if you have a small opening you should port it to match that of your T3 turbo. I recommend maching the turbo and manifold mating surfaces flat and using a metal gasket. It works better than the interference or depression fit of the 82-85 240 Turbos. However, on my 242T I have used the depression fit for 8 years. The manifold was ported to match the turbo inlet.
I recommend using a manifold/turbo brace from the head. One can be triangulated off the two top center manifold studs, using slightly longer studs, and connected to the brace hole on top of many turbos, which is also a triangular shape. This is a custom welding/bending job using quality flatiron or cut up old jack stands.
The factory 700T lower turbo manifold brace could be used alternatively but is not as heavy duty.
Larger studs can be used in the turbo to manifold to prevent breaks there, but this requires drilling and tapping.
A flex pipe should be used in the exhaust pipe since it is too rigid and stresses the manifold to head and manifold to turbo connections.
You should make sure your converter flows properly or replace it with a better higher flowing model since clogged cats cause glowing manifolds,which weakens the bolts and makes tem more prone to breaks.
I remounted the 02 sensor in the downpipe, which is easier to drill and weld a boss onto. The late manifolds have a boss in the runner by the firewall but I recommend plugging this with a large threaded plug.
The stock downpipe bolts up fine. A 700 series downpipe, which relocates the converter to below the car, will not bolt up without cutting and welding to shorten it significantly just after the turbo (the elbow is further away).--