Pics of cracked tubular manifold,

equal pipe length design very different from the one we were looking at last night at Squires, don't know what difference in performance or exhaust note the different designs will give (if any) also note the flexi piece (arrowed) I've never seen a flexi section so close to the flange and why only one???
exhaust was cracked see pic

I know cracking on S/S manifolds is quite common, certainly the last 2 manifolds I had on 200SXs' have both needed repairing, I guess it's the price you pay for tubular manifolds with their thin walled bent tubes.
This one is now fixed so while it's off and before I re-fit it I'm wandering whether to heat wrap it, I know the various pros and cons on normal cars but with the Impreza engine been a flat 4 design this will mean the manifold is more exposed to the elements than a regular straight 4, the question is whether it's worth bothering for the small likely gains, will the wrap just be a waste of time and dirt trap? is it a common thing to wrap the Impreza manifold or something best left to conventional engine lay outs?

 

I've always been told its's best to wrap, speeds up gas exit and keeps under bonnet temps down
Equal length is better for power but lose the distinctive burble, people quote 25 bhp gains on equal length headers

 

Im going to wrap mine tomorrow. Hoping the under tray will keep a lot of the dirt off. Seems a shame to wrap shiney new stainless so I hope its worth it.

 

25bhp seems a lot for headers but I suppose it depends on how poor the std ones are, if they are restrictive then I maybe it's possible,lets hope so

looks like I may as well wrap them then, although mine doesn't have the luxury of a undertray, but what the hell anything for a little more power

 

Its not just the BHP, you get better throttle response.

They also sound better, and we all know things that sound better are faster.

 

The factory set-up is done to keep cost down, far from ideal, equal length headers are "easier" to map and give decent mid-to-top end torque and bhp improvements.

IMHO

dunx

 

yeah std cast headers are always build to a cost, but the they are also built stronger and heavier for reliability it would be no good for Subarus image for fancy S/S to be cracking all the time

re mapping I know this car I've bought isn't (or wasn't) std , I know it had a front mount IC which was removed and replaced with the piece of junk that's on it now, it has yellow 440 injectors (are these std on a '99 UK turbo?) it has a K&N induction kit and full after market exhaust with de-cat and tubular headers I'm assuming that whoever fitted this lot raised the boost and that to support any boost increase and the mods it would need to have been mapped, is it possible to map the classic without a chip or daugther board? or is this only possible '01 on?
I suppose it's always a problem buying a car with unknow spec, the seller was hopeless and didn't know anything about it he even said it was possible it had a TD05 turbo fitted (I'll remove it and check because I can't see any markings with it fitted)
my problem is not knowing the spec could lead to damage if it has been modded and I guess the best course of action is to get the clutch done, fit the later type IC then fit a boost gauge and check that, then work out what it needs to run safe.

just had the ECU out and it looks std no daughter board and all the chips look std, it has Y7 on the sticker with a small yellow sticker that says 'TEK2'

 

I may be wrong as some scoundrels have added stickers to ecu's to bull at selling time...

But a TEK2 sticker MAY imply an Ecutek dremap has been done on the ecu at some point.

dunx

P.S. With 2.5 motors failing like they do, a set of headers would appear to be a small problem ?

 

that's the problem I've no idea what's been done, it could be stock or it may be mapped but if it's mapped and parts have been removed then it's not going to be right, I'll take the turbo off tomorrow see if that's std or not.

 

Once tubular headers start cracking it is only a matter of time before they crack again. There are some very crap tubular heades on the market, very thin walled stainless pipe and poor quality workmanship and some of these have very questionable design including a flexi joint that fails early. The header is subject to frequent heat cycling and if the EGTs get much beyond 930C. the stainless steel becomes brittle.
As for claims of an additional 25 bhp, well I have something in my pocket now that will ensure the sun splits the pavements tomorrow. £1 plus postage.
Other than turbo and injectors, headers and uppipe are probably the biggest factors affecting performance of a Subaru engine.
The original headers made of cast can be ported and coupled to a matched uppipe. Compared to standard the car will immediately feel far more responsive, boost earlier, have far more torque across the rev range and not run out of breath beyond 5500 rpm or whatever.
Tubular headers, even with efficient design are really intended for big power application and it is unwise to fit these without a remap and certainly you won't get the best from them without a remap. Generally all cars below 380-400 bracket are better off with ported headers and above 400 bhp the benefits swing to the advantage of the tubular header and certainly by 420 bhp the tubular header starts to have an advantage.PROVIDING the design of the uppipe has been taken into account.
I have done a lot of work on ported and tubular headers and have a range of eight uppipes to suit differing applications and I also sell the GT2 Spec type tubular headers as sold by everybody else but unless the uppipe that is supplied with these headers is changed any car with these fitted will suffer considerably more lag than is desirable.

 

Heat wrapping is not difficult if you follow these instructions but you cannot expect to achieve a professional standard on your first heat wrap operation unless you follow these instructions exactly.
Because of the cost of heat wrap ties I only use stainless steel tie wire and generally the more ties the better the job.
To use tie wire it is best to have a set of tie wire pliers/ lock wire pliers which makes twisting the tie wire that much easier.

The DEI heat wrap has a stitching down each side to show the amount of overlap required and you should follow the overlap guide stitching where possible.
The wrap should be applied damp but not wet. You can use a house plant leaf sprayer or any other water aerosol/spray to dampen the wrap or set the tap to a very fine trickle and run the wrap through the trickle quite quickly. In a few minutes the water will have spread evenly throughout the fabric to dampen it. The wrap must not be soaking wet because the impregnated chemicals run out.
Wrap from the bottom to the top with the appropriate overlay.
Keep the wrap as tight as possible.
Remember that the wrap on the outside of a bend requires more material and therefore the corresponding inside of the bend will have big overlaps and on a tight bend this can be almost 100%.
Do not cut the wrap in to short lengths but try to apply in continuous lengths and certainly 15 feet at a time.
The rolls come in 50 foot by 2" .
A 3" open neck downpipe wll generally take three quarters of a roll of wrap done properly.
Remember. Keep it tight.
Tie at the end and then every 3 or 4 inches but on curves or corners you can increase the number of ties.
The tie must be applied while the wrap is still damp.
Cut off any strands and loose ends.
When put on the car first there will be a lot of moisture released from the wrap. Do not be alarmed.
On damp and humid days the wrap will absorb moisture so again there will be a lot of steam.
It is quite normal for the wrap to smell for three weeks after applying as it dries through thoroughly.
Happy wrapping.
If you need further assistance please do not hesitate to contact me.

FWIW, I have a set of headers and uppipe here that have just come off a car that were fitted three years ago. The wrap is still in very good condtion but two areas need minor rewrap and I suspect there has been physical damage caused by a boulder or a lump of flying wood on the road. Done properly, wrap will last for several years providing the quality of wrap and workmanship is of good order.

 

thanks for the info,I agree that the headers will probably crack again but the welder did a real good job so I'm hoping it will last a good while, as for power I'm not sure what mine is making it's got a larger turbo fitted and yellow injectors so I'm assuming it's been mapped to suit but I don't know for sure so once it's back up and running I'll get it mapped and see what I've got, I'll have a bash at wrapping the headers and down pipe, I assume the cheap wrap on Ebay is poor quality and I'd be betteroff with DEI or similar? also is there any point wpapping the the big de-cat pipe?

 

It is worth heat wrapping headers, uppipe and downpipe and the exhaust side of the turbo. I also heat wrap the hard pipe for the front mount after the front mount core to the throttle body but not the hot pipe from the turbo to the core.
The problem with the headers is that no matter how well they are welded, the stainless steel material is already in a brittle form and while the weld won't break it is possible for an area adjacent to the weld to split because of the hot and cold cycling.