Fitting the weapon R to a VX

Karlosfandango

I've been reading through all the old posts and have a pretty clear idea of what's needed. I have a full milltek system which I assume looks like this..

So questions time.. Will the flange on the milltek/manifold end be at the same point as where the flange on the weaponR manifold will be? It would just be easier to make the 2-1 section if I know physically a size to make it to, and I assume that making the 2-1 and cat section in one piece will be fine? Whilst doing these mods would increasing the diameter of the U bend to 2.5 be a good idea? And if so do you just grind the weld off at the backbox end in order to fit the larger U section into the backbox?

Cheers notsure.gif

luna_s

you wont be able to use much of the milltek cat section at all.

basically you need 2 flexi joints iirc 100mmx50mm that fit to the weaponR flange which is cut off from the downpipe section

then 2 x 2" 90 bends , then the collector section also cut off the weapon R downpipe - then to a 90 bend of the size of your choice

heres mine (messiest welding ever) - mine stops at a flange so i can have a removable cat section - but you can just have a long straight section easy enough
i just made it harder for myself :lol:

i found it to be a real tedious job getting it all lined up

vocky

I would fit a reducer to where the U bend meets the backbox.

they sell them in demon tweaks, part number U077600R (R = stainless, for mild steel remove the R)

to increase the size of the cat simply cut the cone shorter, this will enable you to use 2.5" pipe 😃

a few pics of mine

Note the reducer on the end of the U bend, it sleeved OVER the inlet to the backbox, every little helps :lol:
actually this pipe made a good difference to power :shock:

rabidh

luna_s said:
i found it to be a real tedious job getting it all lined up

Yep 😃 I put mine all on the car and tacked it up while it was on there. Still a PITA - even with a friend helping to hold stuff in place. Definitely using shorter flexis would help I think - I used quite long ones...

Personally, I'd sell your Milltek section and start again with 2.5" pipe and a bigger 200 cell cat (and possibly 2.5" u-bend as it's a pain trying to find a matching flange for the existing U-bend). I believe those Milltek sections are worth quite a bit of money (isn't the whole system over £1000 new?), so the money you get from it would probably cover the cost of getting all the bits you need for the new 2:1 section, plus a bit. Besides, once you've welded up the curvy bits, the straight bit with the cat on will be a doddle 😉

vocky

thats true, the cat section will fetch almost new money on ebay !

a magnaflow cat is less than £80

cthomas443

If you need a end cat flange i have a miltek one which is currently bored out to take a 2.25" OD, i can bore it out to 2.5" if youd like it. as i now have a t304 flange

Yours for £7.00 posted.

Karlosfandango

Thanks for the info and offer of a flange. My father in law is probably going to do most of the making/doing as he is a welder and has access to lots of big machines at work, I've just got to get the dimensions correct!! If I think of anything else I'll be back.

sdbutler10

sorry to change subject but did you tig your welds on the s\s or have you mig it all?? i have heard u can mig s/s? is this true?

rabidh

It's probably worth trying to make a jig out of wood as it is quite tight to get the 2:1 bend sorted and the cat in - especially if you use one of the bigger magnaflow cats. I'm sure quite a few people would be interested in using the jig after you too!

I attempted TIG at first, but had very little luck - I think mainly because I'm shit 🙂 Stainless MIG wire + Argon/CO2 mix was perfect though... I couldn't recommend it enough.

exmantaa

As I like a more conventional 4-cilinder pairin (1+4, 2+3) on my engine, did anybody look to the Weapon R "Race" header?
Sure it needs fabrication, but looking to the layout I think it might be suited (heat shielding boot!)than this older style (or Tsudo) header.

Weapon R race header:

I also looked to their Elise header, as this layout looks perfect. Have to investigate if it is possible to just swap the Toyota flange for an Ecotec exhaust flange:

(Anybody happen to know the exhaust port distance from a Toyota engine?)
😃

vocky

the toyota looks to shallow, like it might hit the subframe ?

but a bit of cutting and welding might work wonders ....

Karlosfandango

Quick question, how many bolts attach the manifold to the engine? I've tried a search but nothing obvious comes up and I can't fine the link to the workshop manual that someone has hosted on their site. What would happen if I started the engine with no exhaust attached?

Karlosfandango

And just found a chuffing great crack in the old manifold!!

edbutler

Karlosfandango said:
And just found a chuffing great crack in the old manifold!!

That could be the answer to some of that super-rich mapping!! 63.. :lol:

luna_s

iirc its 10 nuts

Karlosfandango

Just got the last one out, it's rather snug in there with the clam on, then took ten minutes to persuade the manifold to come out. The crack runs right from one side under the first branch to the other side.

rabidh

Some people reckon it's bad news to start the engine without an exhaust on. Not sure what it can do tbh apart from having bloody great flames coming out. I started mine with just the weaponR header on, and it sounded gorgeous - shame I couldn't have just left it like that 😃

I was just thinking - maybe i'm totally wrong here but what if you took the weaponR 2:1 section and sliced halfway across it in lots of places, then bent it (so the slots closed up) and welded up the slots... could you get that to 90 degrees, and save all that hassle with the first bit? Obviously there's then no flexi for that bit, but you could put a single 2.5 one after the other 90 degree bend...

winstar

With the calm off then I wouldn't have a prob with starting the engine however as said it'll shoot flames out the ports.

IMO you should go about making the 2-1 section like vocky's cut the flange and then use two 2"x1.5D bends and a peice of 2.5" pipe pressed at one end to make a collector, then make the rest of the pipework 2.5". I'd use one of these cats http://www.nemesisuk.com/mm5/merchant.mvc?Screen=PROD&Store_Code=N&Product_Code=59956&Category_Code=MAGNAFLOW-CONVERTERS to give yourself a bit more space to work. You could get fancy and make longer secondaries that join under the sub frame but it would be alot more difficult.

One thing I would do is junk the Miltek and get somthing with 2.5" piping thoughout even if it's a VXT exhaust.

OAKMERE

I'd use one of these cats http://www.nemesisuk.com/mm5/merchant.mvc?Screen=PROD&Store_Code=N&Product_Code=59956&Category_Code=MAGNAFLOW-CONVERTERS to give yourself a bit more space to work. You could get fancy and make longer secondaries that join under the sub frame but it would be alot more difficult.

That is the cat I am going for this time as it looks very compact to aid air flow around the exhaust and it is also a 200 cell.

Do you think these flanges might be suitable?
http://solid-fabrications.co.uk/flanges.aspx

Cheers Oakmere

rabidh

I did mine with vocky's method (used the WeaponR's Y-piece), and it did work ok, although welding the flexis on so they sealed well was a bit of a PITA. If you do it that way i'd suggest leaving some stubs of pipe sticking out of the flange and then stick the flexis over them and weld. It's also handy because if you put the flexis flush with the flange, it gets difficult to bolt the flange up.

I think it's worth considering bending the 2:1 pipe. Biggest problems I had were sealing the Y-piece and the 2 upper flexis. If you can get around that it would save a lot of time (and money - I think the 90 degree bends were £10-15 each, as were flexis).

I opened up my OEM backbox to 2.5" and removed some baffles then welded it back up - that seemed to do the trick quite well. OEM backboxes go on ebay for around 99p so it's worth a punt. As before, if you sell your milltek backbox too you'll likely end up with a full WeaponR system AND some money left over 🙂

edit: I used one of these cats:
http://www.nemesisuk.com/mm5/merchant.m ... CONVERTERS
But I had to grind the edges down a bit (they're just spot-welded for the heat shield) and put the cat at 45 degrees. All a bit of a pain really, but it will fit... Not sure how much extra airflow you get over the one you guys are suggesting though.