Welding Tips and Tricks

This is combination of wanting to drop some weight from the car and try a make a few more horse power.

The first header flange I bought was for the wrong engine, they sent me a flange for a 5SFE engine instead of a 3SGE.
After they finally got me the right one, it was cut with over sized ports that would have been on use Schd40 pipe for a turbo manifold. But it meant filling the ports in and grinding them to match the ports in the head for use with 1.6mm tube.

Next problem was the ports aren't all the same and #1 port come out of the head at and angle, so I had to match that angle with a short stub. The pipes off #1 and #2 have both become a slight compromise.

Why didn't you just buy one somewhere else? Those guys obviously don't have their heads in the game

They were the only place I could get one. It's a problem in Australia, we just don't have a lot options for many things.

I've had to compromise on the pipe size too, There is no one here that stocks mendrel bent tube in anything bigger than a 1.5xDia bend center-line radius. It's all "custom" which pushes the price WAY WAY up.
So the only thing I can do is go 1-3/4 inch pipe with the tight bend radius instead of 1-5/8 inch pipe on large bend radius.

Starting to look nice!

For the ports being too big, instead of filling them in, you could also have looked at getting some slightly bigger diameter starting pipe pieces/stubs that would have fitted into the holes and then slightly tapered them so your final diameter primaries fit in/onto these.

For a normally aspirated engine such a 'stepped bore' style can be useful where having a bigger/oversized bore pipe right at the exhaust port allows the gasses to expand slightly as they exit the cylinder, creating a low(er) pressure region and drawing the exhaust gas out.

Not sure how it is in Australia, but here in Europe I can usually also get individual 0.8 or 1.5mm wall thickness 90 degree 'welding' bends in various degrees of bend tightness and for really tight ones where actual mandrel bending no longer works also some seam-welded tighter ones that are made from pressed 'half shells' welded together.

Still.. On most manifolds your first and biggest hurdle will be to get everything fitted onto the engine (and not hitting bits like alternators and such ) and into the car/chassis you use.

That will dictate a lot of the choices you have as far as pipe diameters, lenght of primaries and secondaries (in case of a 4-2-1) or pipe routing go and a lot of these will need to be compromises to actually fit in the car..

And then there's volumes of books and theories on manifold design, pipe lenghts and even if (on a 4-cyl) you should pair 1-4 + 2-3 or go 1-2 + 3-4.. Almost religous debates/wars about that sort of thing

For a race car you should at least have a few less restrictions as on a road car you also have to keep in mind the exhaust gas temperatures at the end of the manifold and if they are still enough to get a cat-converter to it's 'light off' temperature or ground-clearance issues for speed bumps and the likes.

Bye, Arno.

Arno wrote:Starting to look nice!

For the ports being too big, instead of filling them in, you could also have looked at getting some slightly bigger diameter starting pipe pieces/stubs that would have fitted into the holes and then slightly tapered them so your final diameter primaries fit in/onto these.

For a normally aspirated engine such a 'stepped bore' style can be useful where having a bigger/oversized bore pipe right at the exhaust port allows the gasses to expand slightly as they exit the cylinder, creating a low(er) pressure region and drawing the exhaust gas out.

Not sure how it is in Australia, but here in Europe I can usually also get individual 0.8 or 1.5mm wall thickness 90 degree 'welding' bends in various degrees of bend tightness and for really tight ones where actual mandrel bending no longer works also some seam-welded tighter ones that are made from pressed 'half shells' welded together.

Still.. On most manifolds your first and biggest hurdle will be to get everything fitted onto the engine (and not hitting bits like alternators and such ) and into the car/chassis you use.

That will dictate a lot of the choices you have as far as pipe diameters, lenght of primaries and secondaries (in case of a 4-2-1) or pipe routing go and a lot of these will need to be compromises to actually fit in the car..

And then there's volumes of books and theories on manifold design, pipe lenghts and even if (on a 4-cyl) you should pair 1-4 + 2-3 or go 1-2 + 3-4.. Almost religous debates/wars about that sort of thing

For a race car you should at least have a few less restrictions as on a road car you also have to keep in mind the exhaust gas temperatures at the end of the manifold and if they are still enough to get a cat-converter to it's 'light off' temperature or ground-clearance issues for speed bumps and the likes.

Bye, Arno.

I subscribe to pairing 1-4 and 2-3. I have some programs to help calculate pipe size length etc and advice from some people on the Speedtalk forum. I'm aiming right in the middle as far as length goes, secondary length and tail pipe length is limited by the MR2 having a mid/rear engine.

I'm building a 4-2-1 system and location of the primary collectors is the biggest headache right now. Having had time to think about what I've already done, I'm almost certain I'm going to cut all the tacks off and start again.

Yeah.. I know the mid-rear dilemma.. I have a Lotus Elise with a K20 engine and it's extremely tight all over the place in these too. Clearances of a few mm here and there.

Just re-did my exhaust system after the manifold for road and track use (dB limts getting lowered all the time on tracks) and had to squeeze some stuff in there that really wasn't designed to fit like an original TypeR cat and silencer off of a later model car, but in the end it worked after re-doing the design about 4 times so I know about tacking it all up and then grinding away to get it to bits again

Oh.. A tip if you are looking for a good heat barrier material in the car around exhaust bits: Teknofibra. (http://www.gssperformance.co.nz/teknofi ... etail.html)

Not affiliated or anything with it, but so far it has turned out to be the best I have found to cover firewalls and heat shields and such.

It's very lightweight but has high heat reflectivity combined with incredibly low heat conductivity so you can often get away with a single layer. Just make sure to put tape over the ends/edges as it's foam-like backing will otherwise absorb water that gets into it.

Good luck with the manifold design! It can be a very dull and repetitive process sometimes..

Bye, Arno.

cut all the tacks off today.

changed the primary pipe diameter and the layout.
One of my suppliers has come good with some 15 degree bends so I can make the merge collectors.
I guess that called progress.

After pulling it all apart, I have made some progress.

You're making some good progress there Brad.

I hear you on the 'limited choices in Australia' thing. It's even worse for bike builders. On the rare occasions you can source the right diameter/material exhaust tubing for bikes, it is usually only available in thick (1.6mm) wall.

Ironically, the rule of thumb seems to be that the thin wall stuff is only generally available in the larger 'car' diameters. As soon as the diameter goes smaller, the walls are thick. Not much good when you're trying to build a lightweight exhaust!

Keep the photos coming - love your work.



Kym

Missing cylinders?
Thought Aussie Supercars had 8?

Small amount of progress tonight.

number 2 tube is a little longer after the step than the other three, but the step is in the right place, collector is in the right place and there are as few bends in each pipe as I could get. Getting those three thing right is worth more than a 15mm of length difference.

Tacked a brace across the tubes to hold everything in place, the whole lots needs to come off the head flange so that I can 'black smith' the round tube into the oval ports. then it has to go on the car to start on the secondary tubes.

one more thing. if you have 2inches of fill rod in your fingers and you want to wipe the sweat off your face, PUT THE FILL DOWN FIRST.

Accidentally sticking the hot end of a fill rod up your nose is NOT a pleasant experience.

brad_m wrote:one more thing. if you have 2inches of fill rod in your fingers and you want to wipe the sweat off your face, PUT THE FILL DOWN FIRST.

Accidentally sticking the hot end of a fill rod up your nose is NOT a pleasant experience.

Yeah. I'm lucky I didn't put my eye out like that.

Just uploading another photo.

Need more practice, but then again, that's partly what this is about.

Actually not bad.. Seen a lot worse from commercial fabricators/sellers

Compensating for the distortion/draw in the welds when building systems is something you'll work out as you create more and more things and get to know how the material reacts and what tolerances you need to keep pre-welding to get the desired end result.

Just a tip.. I personally like to make simple jigs for any exhaust part on my car I design and build that worked out well, so afterwards I can work on a 'version 2' with at least some parts like flange locations and space restrictions already in the jig.

Eg. Use some scrap/leftover flanges and plain steel square tubing and such to create the jig. Doesn't need to take much time but can save you a lot of time afterwards. (or if mates start putting out hints that they want that same system )

Once you don't need to do the constant 'tack-testfit-grind-tack-testfit' of the initial fitup and design it saves a huge amount of time and gives you more time/freedom to look at specific parts you want to optimise/change as your season(s) progress.

Bye, Arno.

Finished, on the car the have been proven on the race track.
Worth 0.5 seconds on 46 second lap.

Well done Brad.

What track are you running on? 46 second lap...that's a short circuit!




Kym

MosquitoMoto wrote:Well done Brad.

What track are you running on? 46 second lap...that's a short circuit!




Kym

It's actually a Go Kart track that we run sprints on.


https://www.youtube.com/watch?v=Ibno2c0B7Qo