Turbo Exhaust Manifolds

Hi guys, seen loads of these turbo exhaust manifolds like this one,

http://www.ebay.co.uk/itm/TOYOTA-SUPRA-STAINLESS-STEEL-EXHAUST-MANIFOLD-7M-GTE-/130480311036?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item1e613b8afc#ht_1608wt_1199,

not necessarily exactly like that but similar (i know this one is for a 7M but just for illustration. Was wondering what the other pipes go to, near the turbo flange where all six go in then two come back out into a round pipe with a flange on it, its seen coming out at the back in the photo, what are those for and why are they like that. Also I've seen designs where the turbo flange is one hole, whereas this one is two, does this make any difference? Was interested in this as i have also seen ones where that other pipe is not there, like on here,

http://www.ebay.co.uk/itm/93-94-Toyota-Supra-Turbo-Manifold-MK4-2JZ-GTE-Cast-T4-/200649751710?pt=Motors_Car_Truck_Parts_Accessories&hash=item2eb7a83c9e#ht_5578wt_1139.

thanks for any help

Brad

Thanks, i get that now, but whats that other pipe for which is not on the manifold in the second link?

the ones which come back out (with a flange) are for an external wastegate

Whifbitz have swapped from the single inlet to the divided one for their manifolds as Paul has found they give quicker spool.

Might be worth giving him a call if you are looking for one.

Tubular single turbo manifold, T4 turbo flange and 4 bolt external wastegate flange.

http://img195.imageshack.us/img195/2779/picture1re.png

http://www.autocarparts.com/images/HKS_USA/Wastegates/racingss.jpg

Cast single turbo manifold, T4 turbo flange and 2 bolt external wastegate flange (the wastegate opening on this cast manifold is way to small to be able to flow enough to control the boost).

http://img545.imageshack.us/img545/2029/picture2yp.png

As said above, the Whifbitz kit looks supremely well made

Detailed by Paul here : http://www.mkivsupra.net/vbb/showthread.php?236548-Garage-Whifbitz-Twin-Wastegate-Turbo-kit

Getting the twin wastegate manifold myself

thanks for the clarification, and yes that kit looks alright, but i think parts may be cheaper if i buy parts separately.

Also what is a 'screamer' pipe, is this basically a pipe which goes from that 2-1 hole flange at the back, straight to the exhaust gases. And in that image that wastegate is plumbed back into the exhaust system, are atmospheric ones better in any way, or is it just the fact that you can here it much louder being the only difference? Is the screamer pipe also vented straight into the atmosphere or do these plumb back into the system?

Thanks

The wastegate can either be vented to atmosphere through a screamer pipe or recirculated back into the downpipe, it makes no difference which you choose performance wise but recirculating the wastegate is a lot quieter.

A screamer pipe is very loud - think of a 3L engine with a 6" exhaust.

well now i think about it, isn't there chance of things getting to hot under the bonnet then and catching fire? And surely the screamer pipes would have to be taken off for MOT's?

Also if your driving the car pretty hard you might end up blowing a lot of the exhaust gases into the cabin?

The pipe from the wastegate should be pulled under the car. so you dont get exhausts in the enginebay. for MOT you would need to make a pipe from the wastegate to the exhaust system.

regarding the heat you would need to make either a heatshiled in some steel, or a turboblanket or both. kinda depends on your turbo.

Screamer pipes are fine from a safety POV so long as they are fed so that gasses exit below the floorpan, the speed you'll be going when on the wastegate is open will never result in them being fed into the cabin.

They are a complete MOT failure though as unsilenced exhaust exits are not allowed, so you will need a friendly MOT centre to get one through. That is never a problem though They'll pass lambda test if you have a race cat as the wastegate will be closed at static throttle.