2H and 12H-T question

[Henry James the 47th]

Does anyone out there have familiarity with the exhaust maniforlds found on the 2H and 12H-T? are they identical or, as I am thinking, do the manifold on the 12H-T flow better because of the turbocharger?

[Tapage]

I'm not sure if are identical .. see my turbo setup thread I found a factory adapter that is bolt on in my factory exhaust manifold and bolt on to factory turbo of 12H-T engines ..

[Jan-78FJ40]

Originally Posted by Henry James the 47th

Does anyone out there have familiarity with the exhaust maniforlds found on the 2H and 12H-T? are they identical or, as I am thinking, do the manifold on the 12H-T flow better because of the turbocharger?

they are not identical.
what do you mean by better flow? what really restricts the flow is the exhaust diameter. if you switch to a 2.5 inch exhaust you'll get much better flow.
j

[Talos]

they are not identical.

but a exhaust manifold from a 12H will fit a 2H right?

[Jan-78FJ40]

Originally Posted by Talos

but a exhaust manifold from a 12H will fit a 2H right?

Yes, I think so. probably the easiest would be to see if the gaskets are the same, then it'll fit.

[UpsideDown]

Generally speaking, the flow characteristics of forced inducion manifolds are different than NA manifolds. For forced induction, certain factors are much less important - so they are designed differently and may actually produce worse flow in a NA engine.

On the exhaust side of things, I wouldn't worry too much about the manifolds, they are short and stout. I'd look at the pipes and see if there are restrictions or sharp bends that can be eliminated. A slight increase in diameter when doing upgrades is beneficial as well, but going to massive pipes can actually harm performance.

[Henry James the 47th]

Originally Posted by UpsideDown

Generally speaking, the flow characteristics of forced inducion manifolds are different than NA manifolds. For forced induction, certain factors are much less important - so they are designed differently and may actually produce worse flow in a NA engine.

On the exhaust side of things, I wouldn't worry too much about the manifolds, they are short and stout. I'd look at the pipes and see if there are restrictions or sharp bends that can be eliminated. A slight increase in diameter when doing upgrades is beneficial as well, but going to massive pipes can actually harm performance.

Alright then, where does "slight increase" leave off and "massive" begin? Is 2.5" too much? What are the typical sizes available, from stock, and where does the size begin to harm performance?

on another note, I've got to extract some bolt stubs in my exhaust manifold, and I think I'll go with the left handed drill approach. Anyone got pictures of what the factory heat shield plate looks like?

[UpsideDown]

Originally Posted by Henry James the 47th

Alright then, where does "slight increase" leave off and "massive" begin? Is 2.5" too much? What are the typical sizes available, from stock, and where does the size begin to harm performance?

on another note, I've got to extract some bolt stubs in my exhaust manifold, and I think I'll go with the left handed drill approach. Anyone got pictures of what the factory heat shield plate looks like?

Slight increase would be in the range of 0.5" to 0.75" diameter, massive would be 2"or 3" increase in diameter....

You can get exhaust tubing in many different sizes.... just have a look online. usuallly piping in exhausts is larger towards the engine and slightly smaller towards the tail pipe. Reason being is that hot gases require larger pipes to flow well and as they cool you can use slightly smaller pipes and have the same flow characteristics. Using the same diameter throughout is easier.

Often there are bottle necks in exhaust systems that can be removed to help performance considerably. Have a look at what you've got and try to figure out where they are.

As for removing broken studs, hopefully there is something sticking out. You can try vice grips or welding a nut to the stick-out (allow to cool well before trying to remove when using a welded nut).

If not, then grind the end as flush as possible and centre punch the stud and drill it. You can use an easy-out type extractor in some cases; in others you can drill almost up to the original bolt's diameter, once you get close to the threads in the head, you can try to pick out the offending pieces. Often re-dressing the threads with tap or thread chaser is a very good idea.

Good luck, removing broken studs can be a real test of patience.

[crushers]

Originally Posted by UpsideDown

A slight increase in diameter when doing upgrades is beneficial as well, but going to massive pipes can actually harm performance.

this statement is true with a gasser, no back pressure

but with a diesel, decent size is 2 1/2" anything bigger will not harm the engine or the performance but is a waste of money.