Bret's MG Skunk Works Success!

[Bret]

Well sort’a

I finally made some time today to pull the old restrictive manifold & Cat and replaced it with my new custom intake & 3 into one header. Don’t worry folks I still plan on installing an aftermarket catalytic converter down the road.

Consider this a fitting & test run – kind of like what they do with development aircraft by testing the engine while on the ground. Well despite some minor hardware issues everything bolted up just as planned and I’ve incorporated all the original emissions equipment (save the cat) and it fired up after a quick jump start from my truck.

Then a surprise! That cool looking 3 into 1 header ain’t so cool looking anymore. Because the paint bubbled up on the number one & number four exhaust down pipe while the paint flaked completely off of the center Siamese (2 & 3) down pipe. In fact the whole header is going to have to be completely resurfaced. But that’s why we have test runs like this – rather than while driving down the road. Anyway once I figure out where I’m going to place inline Cat with a flange fitting – I’ll have it either powder coated or jet-hotted along with the custom intake.

By the way – during my test run I’m sure I PO’ed a few neighbors because I was running strait headers. As cool as it sounded I’m going to have to figure out something temporary to link the header to the rear muffler for harmony of the neighborhood. /bcforum/images/%%GRAEMLIN_URL%%/wink.gif

So what ya think?

 

[kyreb1862]

This is great! I know I am certainly well satisfied with my Austin Marina setup and your setup is very similar. My intake/exhaust is Jet Hot coated and seems to be holding up well after 4,000 miles. I'll be watching to see how the F.I. works out on the new manifold because this is something I would like to do on my car.

Regards John

 

[1965_MGB]

Guys like you are great. I wish I had the skills to fabricate stuff like that.

Putting on a cat should not be an issue, there are some high flow cats out there that should fit right in. They are pretty small as well.

 

[Nunyas]

nice! nice!

I agree in that there are some compact high flow cats out there on the market now. I'm certain your local 'custom' muffler shop will be able to do what you want with that.

 

[Bret]

Thanks gents!

As far as the Cat goes - I'm planning on using a smaller (pre-cat) made by Magnaflow #50004.

Pre-cats tend to be smaller to allow better placement of the regular cat on larger engine farther back away from the engine. I’m going to try to see if I can get my local muffler shop to place it just after the collector in a Simi vertical location before the 60 degree bend towards the rear of the vehicle. Tight fit to be sure but it wouldn’t be any worse than the told layout. Worst case I may have to place it just after the bend horizontally right under the drivers footwell. But with my lowered suspension – I’m afraid of dragging or tearing it off the first time I hit a speed bump a little too fast.

Something else about pre-cats that all us LBC owners should think about – is they tend to be much smaller (3" in diameter vs. 4" & 5" for most) and using Magnaflows caculator & doing the math, the one pictured above is more than capable of handling up to a 3 Liters of displacement all on their own without a secondary cat. So our little 1800cc engine shouldn’t be a problem for them. Especially with the Moss Motors EFI kit. I’m thinking I should sail through the tail pipe emissions part of the testing with flying colors.

Adding to that is that - is the fact that this modern & freer flowing cat design is about half the cost of the OEM style ones that Moss & others sell for our late model MGBs.

 

[Bret]

Alrighty then.

So after piecing the exhaust back together again I jump started Pagan. Now I’m a little surprised how loud the header is compared to the regular exhaust but then this is an experiment and the sound of the exhaust isn’t the focus here. Besides I’m thinking of installing a Peco (muffler & pipes – no header) exhaust system and use it with my short 3-1 header (Moss PN#459-011) that I plan on mounting the Magnaflow catalytic converter (PN#50004) that I ordered from JEGs (item #642-50004).

All & all I was impressed with the throttle response and that it seemed to want to pull for ever but avoided pushing it beyond redline. However it does seem to lag a bit – RPMs rise but I’m not taking off the way I think I should. I know I mentioned this before and everyone kept thinking my old cat was clogged – but that’s out of the picture now. Granted – when I pulled to old OEM style cat is was destroyed but it didn’t look that clogged or obstructed to me as I could see light through it.

Anyway I think the real problem is that my clutch is slipping. Now this is a brand new unit and I paid my mechanic to install it for me with my new (used) O/D unit I got off of ebay about a year ago.

Another possible cause for the bogging down (although not as bad as before) could be that my camshaft is warn not allowing my engine to breath as well as it should. But that’ll be taken care of when I swap in the new cam.

Speaking of the new camshaft install – I will be putting on the alloy head a the same time. But I’d really like to make sure I’m not dealing with a burnt & slipping clutch.

Any ideas on how I could check this without tearing it apart?

 

[Bruce74B]

Yea, Bret,

Get 'er warmed up, take 'er out and power shift it from 1st to 2nd at about 4000 rpm...if the tires chirp, you should be OK /bcforum/images/%%GRAEMLIN_URL%%/driving.gif

 

[kyreb1862]

Have you had your distributor recurved to match the new setup?

Regards John

 

[Nunyas]

if the clutch is slipping, you'll be able to recognize that easily by the engine RPMs rising while your speed is not changing at the same rate as the RPMs. I.E. It will be acting like your riding the clutch too hard while driving.

"Bogging" can mean several different things to different people. For me, bogging is when I go W.O.T. at idle and the engine acts like it is 'slow to respond' until it hits the 'power band', which, on my car, is anything under 1500 - 2000 RPMs. If I keep my RPMs above that, the response is dang near instantaneous. The way I figure it, my down low response is a factor of several things: fly wheel weight, all the gadgets running off the crank pulley, internal engine resistance, breathing efficiency, etc. However, I tend to lean more towards rotational mass being the biggest culprit in slowing 'spool up' from idle.

 

[DrEntropy]

With an 1800 "lump-o-iron" B engine, if you are going WOT below 2K you're lugging it. That's what first gear's for... get rollin' so's second is over 2K! /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif

 

[Bret]

Well I was thinking it was bogging down but RPMs where up and infact rising but the car was hardly moving.

But again I'd just replaced the clutch and wouldnt' thhink it'd fail right out of the box without some thing serious happening to it first.

Oh well I'm putting a few things together as I speak and will probably be taking it out for another test run later in the week. So I'll have more info at that time.