Hello, Iam looking for a little help here on a conversion project. I transplanted a 12v cummins into a 91 f-350 crew cab. the problem is the exhaust outlet is to close to the heater/ ac .So I need an exhaust manifold that positions the turbo closer to the engine or a bit forward. Any help most appreiciated.

 

Medium duty truck manifolds tuck the turbo in closer to the engine and further down beside it, imagine your current manifold with the turbo flange welded to the bottom of it - that's what it's like. That would help with the heater but might cause interference with the frame. The manifolds can also be installed upside down, I've seen this done with Dodge manifolds on twin turbo setups and with truck manifolds on industrial engines.

 

Maybe these guys can help

 

First, the industrial manifold will not work, the turbo tucks in too close to the engine and you have to relocate the right side motormount and cut out part of the frame (not good). That is a real pain in the backside! Flipping the OEM manifold upside down creates a major block with the Ford hood, so build your own downpipe or you will be driving with no hood.

I do these conversions pretty frequently, and what I do is get the 4" turbo outlet from Piers (his part number PDR1010500, for around $50), then get the straight connector for the new outlet for a motorhome (cost is about the same and you have to ask Piers specifically for the connector that hooks MH exhaust systems to the HX40 turbo - it is a straight chunk of SS pipe with the connector flange that hooks to the new outlet - If you have a lathe you can make your own from a cylinder liner), then weld a 90 degree 4" stainless steel elbow to the connector, and take the exhaust straight down and tuck it next to the engine to keep it away from the plastic heater and A/C housing. NAPA sells some header wrap for around $18 that I also wrap the new handbuilt downpipe with to keep the heat in.

It will be a tight fit, but with some care you will be able to cut and fit the pipe sections and then make the second 90 degree turn to connect to the new exhaust. Using this method also eliminates the totally worthless and leaky cast iron ball on the end of the OEM style downpipe, so you will not get any exhaust leaks and stink in the cab when you are done.

The new stainless steel downpipe will last forever, so take your time and do it right. I get my stainless stock from NAPA for around $90 for everything, including the two elbows. When you order the elbows, get the tightest radius you can so you can make the turns. Then dry fit everything and you may have to bend the pipe in a spot or two, depending on how deep and back you installed the engine in the Ford engine bay. I generally set it forward enough so there is 4" of clearance between the engine and the firewall, but some guys set it farther back.

 

Will the 4 " outlet set in closer to the engine? As the engine sits now the stock pipe clears the heater / ac box by 1/4". Also I don't think I have 4 " clearance between the firewall and bellhousing . Thanks

 

Ok heres how it works flip the exhaust manifold upside down then clock the turbo around until the oil outlet is down next clock the air inlet around until it hits the manifold mark the manifold note the position the intercooler feed needs to be in and grind the manifold for clearance. Does not interfere with the hood repositions the exhaust outlet 2 1/2 inches away from heater ac unit. Cheap and easy