Best Exhaust Manifold?

[carockwell]

What is the best exhaust manifold for a modified 1275 street motor? My knowledge is 20+ years old. In those days everybody bought an LCB set and they all cracked within 5000 miles. What are people doing today?

[tmsmini]

My own two cents is the later model cast manifold with a Maniflow down pipe. This is what was used on the SPi and MPi Minis.
You do have to block the port it has for an 02 sensor. Supposedly it was tested against LCBs and was very close to the same performance.

[MiniDave]

I think a Maniflow LCB is fine - does your car have pot joints or Ujoints? It makes a difference in that with ujoints the twin pipe into a collector style doesn't fit and will hit the ujoint.

Also, don't get the biggest bore they sell, you don't need it and you'll actually lose power unless you have a full on race engine or forced induction.

RC 40 exhaust has a nice mellow but good sound.

Edit: Just FYI, the manifold tmsmini mentions requires metric nuts on the exhaust pipe end

[94touring]

Maniflow LCB stage 2, part number C-AEG376 from minispares.  Twin box rc40 1-3/4" the rest of the way back.

[MiniDave]

Those only work with pot joint cars, just FYI.

[94touring]

Pretty sure I had that manifold on the 66 too without any problems.

[94touring]

Spares list C-AEG365S as fouling on earlier coupling types but they sell a lower profile coupler that is supposed to help. The exhaust I listed they don't say anything about fouling.  There's a stainless version too.

[tmsmini]

This is the one I was referring to. I actually got this one from Dean awhile back and it had been converted to non metric, also coated.

It seems exhausts vary a bit with fouling. I have this same manifold/downpipe combination on all three cars and on one the pipe is very close to the diff, all with rod change shifters.

[MiniDave]

I just bought metric nuts!   ;D

[carockwell]

The car is a Heritage shell with a rod change tranny and pot joints so a Maniflow LCB will fit. That is what is on the car right now, though it is quite rusty. My obvious concern is the longevity of the Maniflow LCB system. The link between the manifold Y pipe on the bottom of the car and the exhaust tube stretching to the muffler really needs a flex joint and I am surprised nobody makes a system with this. All the vibration and movement of the motor is transferred to the exhaust system and it just seems stupid.

The car currently has the twin box RC40 system. I also have a brand new Manifold exhaust system with some sort of tapered cone secondary pipe on it I bought ten years ago and never installed.

I was wondering if springing for the stainless Manifold Stage 2 LCB system would result in a more robust exhaust system than the standard mild steel type.

Going with a cast iron system appeals to me because it would seem to be a more durable system all around. I was planning on installing a wide band sensor as a permanent fixture to the car, so the oxygen  sensor bung is a plus. If the power output is similar to the LCB and somebody sells a complete exhaust system with a sensible flex joint then I would probably go with that setup for the peace of mind knowing that the system would stay together without cracking. Reliability is first, power is second.

[94touring]

I've only ever had problems with the muffler cracking where the pipe meets the muffler box.  Maybe I just didn't have my rubber exhaust mounts done properly.  Never had an issue with any manifold. I put 02 bungs just past the collector where it meets to 1 pipe.  For my turbo exhaust I've yet to setup I do have a section of flex pipe I planned to weld in.

[tmsmini]

This is the other piece for the cast manifold.
I am not 100% sure the O2 port is the best location for a wide band. It may be a little close to the head. It is what they did for the stock narrow band and it is what I am using.

[MiniDave]

You could also just have the new header you have ceramic coated, that should make it last pretty much for ever.

Stainless is a good way to go too.

As for flex pipes, you can buy those in all different lengths right from your closest autoparts store.

Don't most widebands want the sensor at least 18" from the head?

Does anyone sell the injection exhaust manifold? I'll bet thousands of them have been thrown away when replaced with headers.....

Edit: Yes, MiniSport has it listed for £130.....LKC10090 - I would def have that ceramic coated. Of course you need the down pipe and gasket too

[tmsmini]

The cast manifolds show up on Ebay UK frequently, but shipping is an issue. Someone in LA has a NOS version on Ebay that they want a fortune for.

I gave one away many years ago before I realized that they actually work pretty well.
I have always had leaks at the y-joint with LCBs and occasional cracking probably due to not being properly secured to the transmission.

[John Gervais]

In my opinion, the issue with LCB's cracking is that folks either don't properly utilize (or tighten) the proper diff. mount support plate or they tighten the pipes & boxes first and then the diff plate afterwards.

As for exhaust pipe hangers, I like  (and use) the competition-grade C-19G3257 and C-19G3258 mountings - they'll surely last a lifetime.

[carockwell]

What is the proper diff mount? The one that comes with the Maniflow headers is pretty Mickey Mouse.

[MiniDave]

Sometimes I can bend that long tab that comes on the new headers to a better angle, the main thing you want is for the flex to take place after the header.....you want the header to move with the engine and not be a hinge between the engine and the body. For my own cars I add a short flex pipe after the header to take up some of the vibrations.

John I always tighten the header to the head solidly, then add the brace down at the diff as a support. After that's all done I add the rest of the exhaust system, get it all situated where nothing's going to touch, then tighten the clamps last.

[tmsmini]

I have been using this heavy duty version from Seven:

[carockwell]

With the Seven Enterprises mount in place, you are able to run a Maniflow LCB ,with the Y pipe, and the standard pipe back to the muffler with no problems?

[tmsmini]

Yes, one of our cars has that configuration. At one point they all did, but I am switch over to the cast manifold.

It requires some fiddling to get it to line up correctly and I use a spacer to align it. I use it with the cast manifold and the maniflow downpipe as well.
I thought I had a picture, but I cannot find it.
Terry

[tmsmini]

Not the best picture, but it shows it in place. You can use the straight extension that comes with the LCB to make it easier to align.

[John Gervais]

The bracket that tmsmini posted is Seven Enterprises version of the original GEX7526 (the alternative is GEX7088) - available from MiniSpares.

[MiniDave]

I know this is an old topic now, but the 5 year old or so Maniflow LCB on my car was cracked in the middle of the Y too, and it had the correct support at the bottom bolted on good. FWIW.....

I think it was cracked when I got the car for that matter, I just didn't know it. But I sure could smell it when the windows were down.