Exhaust manifold construction

[The Mariner]

Hi Everyone,

I'm going to fabricate a steam pipe manifold to fit a TD04 turbo to my 1.6. It's in a locost clubman, so I don't have quite as much room under the bonnet to work with as in a normal MX-5.

At this stage I think it'll be easier to package it all in if I make it a 4-2-1 design by joining cylinders 1 & 2 to one secondary pipe and cylinders 3 & 4 to another secondary pipe, then merging the 2 secondaries at the turbo flange.

Is this a dumb idea? Will that arrangement have any negative effects on performance compared to a 4-1 design or a log manifold ?

If it's not a silly approach, would it be best to increase the secondary pipe diameter to allow for the extra volume of gas, or better to leave it the same size as the primary pipes to keep the gas velocity up given the 2 cylinders (1 & 2 or 3 & 4) fire 180 degrees apart ?

Thanks heaps in advance for your help.

[NitroDann]

Photos of engine bay please.

Dann

[The Mariner]

Please excuse my fat guts & ugg-boots in the 1st pic

The cam cover fits into a bulge in the bonnet, so I can't have anything up much higher than the exhaust ports. My thought was to come out of the exhaust ports & go straight down, joining ports 1-2 & 3-4 together on the way down, then do a 180 with the 2 secondaries (maybe 1 either side of the engine mount) & come up into the turbo flange.

[NitroDann]

Built motor?

Fuel?

HP goals?

Dann

[The Mariner]

Hi Dann,

Built motor? - No, stock.

Fuel? - 98

HP goals? - Modest. Only looking to use around 5-8 lbs boost.

No intercooler, already running a MegaSquirt. Basically doing one of your 'turbo for $2000' builds.

[NitroDann]

Do a log manifold

Dann

[The Mariner]

That's the problem... I don't think I have room for a log manifold 'coz it'll position the turbo too high.

- If the face of the turbo flange is vertical on a log manifold, the turbo will hit the bonnet for sure.

- If I angle the flange downwards by, say 45 degrees, I reckon the turbo will hit the bonnet or chassis frame.

I could mount the turbo upside down, clock it & run a simple manifold from the head down onto the turbo flange, but access to all the nuts & bolts would become an issue

I have the most space if I can lower the turbo down into the space between the motor & the frame. Down there, I believe I have enough gap between motor & chassis to fit a vertical run of manifold pipes + the turbo itself. My though was to make a manifold with pipes that makes a 90 degree downwards turn off the head, tuck close to the block & then do a 180 degree turn back upwards. Basically, from the front the manifold would look a bit like an 'S'.

I know I will have to do a mock-up with flexible hose to see if this will fit, but if it does is there a good reason not to do it this way ?

Thanks for your help

[Okibi]

As strange as it sounds, since HP goals aren't huge, is there any way to put the turbo back near the diff?

[NitroDann]

Response will be crap.

Have you considered building a log, then cutting a section off the bottom of a 'T' and using it as the outlet facing downwards?

Dann

[Okibi]

If you measure the amount of pipework in a FMIC on something like a WRX then it's probably as long as from the clubman diff back to the throttle body. No ideal but it might solve the problem.

[NitroDann]

Its isnt intercooler piping, its enthalpy. its the total energy in the exhaust gases being significantly reduced due to loss of heat.

Dann

[Okibi]

Exhaust Wrap could help a bit

[The Mariner]

Thanks for the replies guys.

I had another look at the space I have to work in last night & think I might be able to do as you suggested Dann... make a log with a downward facing outlet. It'll make access to nuts & bolts a bit harder, but might be the best in the long run. I'll just have to tack something together & see.

There's room back by the diff for the turbo but getting pipes to/from it would be a PIA. There's not much ground clearance to play with & the tunnel is only just wide enough for the powerplant frame & tailshaft.

[hks_kansei]

Being a clubman thing, can't you just have the turbo high enough to fit over the frame rails etc and simply have a cutout/blister in the engine cover to give room to the turbo?

Like this:
http://www.thevintagepanelworks.co.uk/w ... lister.jpg

[The Mariner]

Yes, I could do that but I'm trying to avoid cutting holes in expensive fibreglass. If that's the only way to do it then I'll do it, but that's Plan B.