exhaust manifold

[ensign42]

Okay- so this is basically opposite of every manifold thread I have read so far. I have a set of headers on my engine. My goal is a very solid, as close to concourse restoration as I can manage. Internal changes are going to be a slight increase in bore (just clean up), cam shaft grind, big valves, etc intake will be ported and polished. Nothing extreme. That said- a big tubular header while a great improvement is so obvious when the hood is open it has become a source of concern to me. So, I have two good factory manifolds, but how can I use it without a huge loss of power that obviously a header solves?

So basically- what advice does anyone have on going back to stock?

Thanks!

Will
1966 S2 elan

[jimj]

With big valves and appropriate cams. I suspect the porting and polishing will help a little, and a little more with a bigger bore exhaust manifold but I reckon by using a standard manifold you will hardly tell the difference on the road, only in the bar.
Jim

[Gordon Sauer]

This is one of those things that seems to go so either way with people. That is, people refer to "period" changes like in having Panasport wheels although not factory. And I guess the same goes with headers. It's more of a problem with the federal spec motors because not only is the exhaust manifold different but you also need to be able to tie in the crossover tubes and then have the intermediate throttle body. Perhaps the biggest conglomeration was my choice to keep all of that Emission stuff but just dead end at headers without a connection. I just really wanted to keep the headers and yet visually the crossover pipes are a real marker for the engine. That's my solution and in the end that's what it's all about Gordon Sauer

[holywood3645]

Panasport......? I think you meant Minilite

James

[StressCraxx]

Will,

The S2's were sold with the S/E special equipment. Cams, bigger chokes and jets, a nice 4 into 2 into 1 header. So a header can be considered 'period correct'.

Dave Bean sells a really nice one, in 304 stainless. Fits great, power really comes alive above 4500 rpm.

Go for it.

[AHM]

I understood that the S3 S/E had a cast iron 4 into 2 Steel 2 into 1 manifold and the S4 had Fabricated steel 3 part 4 into 2 into 1.

Exactly how much of a "Great improvement" and under what conditions?

[StressCraxx]

I understood that the S3 S/E had a cast iron 4 into 2 Steel 2 into 1 manifold and the S4 had Fabricated steel 3 part 4 into 2 into 1.

Exactly how much of a "Great improvement" and under what conditions?

The SE gave another 3 HP. The S/E that I know (still in the hands of the original owner) had a fabricated steel tube manifold. His is one of the earliest, picked it up at the factory.

[Quart Meg Miles]

The SE gave another 3 HP.

That's what the Workshop Manual says but it also claims it's only 93 BHP. Wilkins book makes more sense of the engine's evolution even if Lotus did rather overstate their power in the early days.

[ensign42]

Can someone toss up some pictures of an actual factory example of each of the items? I feel like the correct thing to do would be to use the factory original (I got it with the car). But if the later item is externally identical I could be twisted into it I am sure. If someone has a good set of specs on a factory 66 era tubular manifold I would consider that, in mild steel, possibly with a jet coating.

[AHM]

Here is the 2 part S3 S/E manifold from my 67 car.

My S4 S/E had the original fabricated m/s manifold - which is commonly available.

There is a good illustration in the parts book.

I ask about the improvement as it isn't a straightforward +x HP gain

[cal44]

I'm into the cast iron manifolds. But the Federal manifold leaves me D.O.A.
The non Federal manifold when hot coated looks sharp. And, it is a header, just in cast iron.
The weight is negligible for me. If I want to go faster........I'll stop eating so much

mike