Fitting an External Wastegate and Screamer Pipe

I have been looking at parts that I could fit to a 306 when I get one. My aim is to create one of the best set-up cars in terms of turbo performance and the map that goes with it.
In other words I want to get the very best torque curve and best boost rise and hold as possible.

I have been looking at ways of controlling the boost and the normal ways such as bleed valves and check valves just seem to have too many down sides. One of them being that they creep really easily when you start to raise the boost. This is no good for getting a good rise in boost.

Looking around the internet the best looking option is to go with an electronic boost controller. A lot of modern cars use electronic boost controllers but the 306 HDI's doens't have boost control programmed into it's ECU.
If I am going to get a good controller then I may as well go for a good wastegate to go with it. One that isn't built into the turbo and causing turbulence in the air flow behind the turbo. This is when I got the idea of fitting an external wastegate.

Having looked around on the internet I couldn't find much info. I then decided to look for a 306 HDI exhaust manifold on eBay just to see what would be possible with one. It's then that I noticed that the EGR valve has an output on the exhaust manifold.

306 HDI Exhaust Manifold

Most people when tuning a 306 HDI remove the EGR valve or at least disable it. That means that there is then a free output on the exhaust manifold that could easily be utilised for an external wastegate. Even if an adapter has to be made it won't cost a lot and it looks like it would flow well as well as it is branching out directly from the side of the input to the turbo. Very nice!

Looking on eBay for external wastegates seems to show that 38mm wastegates are the most popular sort of size. It looks as though it would fit quite snuggly onto the EGR flange on the Manifold.

External Wastegate

All being well that would give some seriously good boost control when paired with a decent electronic boost controller. When the fueling gets mapped to the boost levels it would allow for some very good low end torque as the boost will come on quicker and also allow for higher torque in the high RPM band as it keeps the boost pressure under control higher up the RPM range.

Fitting a screamer pipe may make the car a little loud but this would only be when I would be at full boost and almost never really occur at lower engine loads such as everyday driving without full throttle acceleration. If it was too loud then I could always fit a miniature 38mm silencer or something to quieten it down a little.

Screamer Pipe

If it wasn't too loud I could get a pipe made up or even use exhaust flexi pipe wrapped in heat protective wrap and then have it exit the car on a small exhaust tip mounted behind the front right wheel of the car. This would muffle some of the noise as it would be a longer pipe as well.

Thanks for reading.
Jack

Exhaust Options

I have been doing my research while I have been looking for a car and one of the things I have been looking at is the exhaust set-up.
Now HDI's have got a Catalytic Converter but they are known not to be needed on these cars as they do not produce enough emissions to fail the test at an MOT even without one being in the exhaust.
However if the car was fitted with one standard then you still need to technically have one.

There are 3 types of exhaust setup that I have often seen for the 306 HDI. I will start at the cheapest and work upwards.

Modified Stock Exhaust £10-60

This is the cheapest possible way to get a free flowing exhaust on a 306 HDI.
What people tend to do on 306 HDI's is smash the cat out of the box it is in and then put the box back on the car. This basically involves taking off the catalytic converter and then shoving a peice of wood or metal bar through the centre of it to break the cat out. It creates a free flowing cat but wont increase the size of the exhaust. It can sometimes also cause turbulence in the exhaust pipe as any left over parts in the box will cause the air to swirl and buffet.
 Once the cat has been smashed out the next part is the centre silencer. Most people remove the centre silencer on the HDI's and then just weld a piece of straight pipe in its place. This does the job really and will free up a little more flow.
 Finally is the back box. Now this is the harder part to do on the cheap. The common way people seem to do the back box is either to take the regular centre section and put that in place of the back box. Or to just put a straight through pipe in it's place. The first way would need quite a bit of welding work and aligning to make it look neat. The straight pipe will often make the car quite loud but not overly stupid really.

Custom off the Shelf Exhaust £180-£230

The next cheapest option is to buy the exhaust parts off somewhere like eBay. On the 306 HDI there are 3 sections, the catalytic converter, the centre section and, the back box.

You can find on eBay a straight through replacement for the catalytic converter. If you search for "Peugeot 306 HDI Exhaust De Cat" you will get a big list of parts. The most popular one looks like this and is a straight fit for the original position. It costs around £50 and will fit in the original catalytic converter place.

306 HDI De-Cat Pipe

The next part that you would need is the centre section. Now as standard the 306 HDI centre section is not that restrictive anyway but replacing it will still gain a little bit of extra flow and performance. The centre section will cost about £40-£55 and can also be bought on eBay.

306 HDI Centre Pipe

Finally is the back box. This part on the HDI is known to be really rather restrictive as it has lots of baffles in it. You can find a few different back box's on eBay, Most of them are made by sportex. They would free up quite a lot of flow and will lower the RPM that the turbo spools at. You can also keep going up though the revs and the engine won't feel as restricted. They can be bough for around £90-£110 and are a direct fit.

306 HDI Back Box

Fully Custom Exhaust £300+

For the perfect exhaust and best performance and look you can go for a fully custom exhaust. You can specify the size that you want and what sort of metal it will be made out of (Although Stainless Steel is always recommended) Usually people aim for around 3" and as straight through and free flowing as possible. This helps to spool the turbo up sooner and releases the potential of the turbo at high rpm and high flow situations. They are costly but if you want to do it properly then they are the best option so long as you go to a good reputable manufacture such as Miltek or Powerflow. They can be tailored to your needs and you can specify how many silencers and what type of back box you would like which makes it very easy to get what you want.

Thanks for Reading,
Jack

Getting The Car

Hey all,
Welcome to my new blog. This blog is going to be aimed at the tuning of the Peugeot 306 HDI. I am going to try and write up every modification I do the car that I plan to buy.

First off though I have to buy a 306 HDI. They are fairly rare to find now with less than 100k miles on the clock which means that I am going to have to do a lot of searching before I even get hold of one.

I am aiming for one with around 70-80k on it so that at least I know that when I start tweaking things it will be able to take the extra strain. I would like to be able to try and get one with a decent service history on it as well but I doubt I will be able to find one with full history.

Thanks for reading, I will update soon.

Jack