Simple Turbocharged Zetec: Build Diary

[ganges]

you sir are a little tease , I am never likley to do this, but well presented, and explained, if i may say so

[Stu]

It's also a good idea to spray any nasty bolts with penetrating oil (e.g. plus-gas) at this point.. items of a particular pain are exhaust manifold studs

[sidrick]

How should you remove the head locating dowels?

[Stu]

How should you remove the head locating dowels?

 

One technique is to find a socket or something that fits nicely in the dowel and use this to keep it in shape when you remove it with some mole-grips or similar.

[waynegc123]

I really enjoyed reading that, So much information !! :drool: Loving this

 

Thanks Stu!

[maxwax27]

i want that turbo lump lol

[lee grout]

Already looking forward to the next installment

[Yule]

Lol, You'll probably get fellow engine builders on your case anytime now crying coz you're giving away all this info to the masses! Jolly good.

[Danzetec]

Good write-up Stu, looking forward to the next stage

[shifty]

This is going to be a good read.

[Stu]

Right.. let's proceed..

 

So the block is now stripped and ready to go to the machine shop with the crank shaft once the pistons arrive. In the mean time I picked up an inlet manifold from a Fiesta RS1800i (also used on the 130ps Escorts).

 

 

You don't NEED the 130ps manifold, or throttle body, for the kind of power I was looking for, but it doesn't hurt and leaves you some capacity incase of urther power increases. Less is more when it comes to engine specs - you want to use things that are as small as possible to achieve what you want, reliably. This means pipework, intercoolers, turbochargers, ports, valves, throttle bodies, everything. If you go 'too large' on any item it will most likely negatively affect response or low/mid range torque. Of course you can go too small too, which may affect other things in the engine (for example a restrictive exhaust manifold can make the engine more detonation-prone, even though it makes the power - it'll also make the engine run hotter).

 

Anyway, here's the manifold and injector holder after a brief clean up:

 

 

 

Here you can see the fuel injector holder in some more detail. You'll notice how mint it looks inside - this is due to the cleaning effect of the petrol. This inlet manifold is designed to use side-fed injectors, which basically means the injector is sitting in a bath of flowing fuel.

 

 

This engine will be using some very rare Bosch side fed injectors in the holder above. They were fuel injectors used by Cosworth in the Indy Car programme and a few batches of them were made available (most likely out of the back door!).

 

They flow 300cc/min @ 2.7 bar (OEM fuel pressure), or approx. 400cc/min @ 4.5 bar. With a turbocharged engine (with a BSFC of around .55), you want about 5 times the total flow in comparison to your horsepower target, e.g. 300hp you want 1500cc total flow, which on a 4 cylinder engine is about 375cc/cylinder. So as you can see, the injectors i'm talking about will be good for just over 300bhp (at the flywheel). You want to choose a fuel injector which is using most of it's linear range in operation - this means you're using up to about 85-90% of it's capacity at your peak power. This gives you the best atomisation and most importantly, better control at the low opening end of the operation (e.g. your idle). If you put massive injectors in an engine, you can struggle to control your idle properly and meeting emissions regs can be difficult, or impossible. Good luck passing an MOT with these 1000cc injectors that you'll see some people using! You're better off running eight smaller injectors rather than four big ones. Just look at the Sierra Cosworth RS500 (and rally cars) - they ran 8 injectors for a reason!

 

Anyway, enough blogging about that, here's a photo of a box of bits:

 

 

 

Remember, always keep everything, you never know when you'll need it! (until you've finished the build & installation!). It may not be a part you will re-fit to the engine, but perhaps you need something to measure, or something to manufacture something from (like a pulley or something).

 

 

Okay, so I thought i'd spruce up the inlet manifold and cam cover. I had both bead blasted (I think, perhaps I cleaned them by hand, can't remember now).. For some reason I thought that silver would look good.. so gasket faces masked up, and some paint:

 

 

 

 

 

Now the above photos show some pretty poor masking. You always want to mask off mounting surfaces for fixings (bolts). Paint compresses when you clamp a bolt head against it and with temperature changes (both atmospheric and during engine heat cycles) bolts can become lose. This applies to everything on the engine.

 

Also as a hint, on the cam cover you put ten or so rubber seals in the bolt holes. I would recommend masking these up too to prevent any oil leaks in the future. I didn't on the photo above as you can see.

 

 

 

Okay, so let's get kinky. Here's some photos i'm sure will appeal.

 

Pistons arrived. They're genuine Mahle pistons designed to go in the Vauxhall C20LET engine. These pistons come in two versions, these particular ones are the forged ones (have 'P' in the part number IIRC). These pistons are not a straight swap, they are a larger diameter (86mm vs 84.8mm stock 2L zetec), and some other geometry is different. I will explain what other changes are required to use these later.

 

 

 

 

These pistons weren't cheap. Probably in the region of £600/set at the time, brand new. You can pick them up pretty cheaply these days, especially if used, but to be honest I don't like to skimp on these critical components so new is always in my list. There are some newer Vauxhall engines, like the Z20LET which may also have similar geometry pistons, but i've not looked much into it.

 

You can also use the C20XE pistons which come form the normally aspirated 2 litre engine from Vauxhall (The LET pistons are from their turbo engine). The XE pistons have a flat top design so your compression ratio will end up higher. They're also typically low pressure cast rather than forged, but i've seen them used successfully in many Ze-VH engines and also (relatively) high compression full zetec engines (this is possible with long cams and/or high octane fuel).

 

 

So onto the connecting rods, or con-rods do you and me. These particular items were a special order from Farndon via Burtons as they have a larger small end diameter designed for the Vauxhall pistons (21.00 vs OEM 20.63mm). It doesn't sound a lot, but it makes a big difference when it comes to bearings in rods.

 

 

 

These rods are superior to a lot of the junk you find out there (like Eagle). They actually use a steel-backed bronze bush rather than a solid bush. This gives much better performance and greatly reduces the risk of 'doing a small end' at some point in the future. As I would be running a 'fully floating' setup, this is important. Fully floating means that the wrist (Goodgeon) pin (in the piston) rotates both in the piston and in the small end of the con rod. Semi-floating means that the pin is pressed into the small end of the rod and does not provides inferior cooling or lubrication.

 

 

So now the pistons are available, and the block has been stripped, they will both go off to the machine shop. It's important to send both together so that the pistons can be measured when they are acclimatised with the cylinder block. A lot of people make the schoolboy error of just sending a block to the machine shop and asking them to base it on the measurements written on the underside of the piston, or on the box! This often leads to a slappy engine... As these pistons are OEM quality and not made of the same kind of material that common aftermarket pistons are made of, they can run to much finer tolerance for piston to bore clearance. IIRC the clearance desired was around 1.7 thou, compare to 3-4 thou for typical forged pistons. This makes it even more important when machining the block to get the clearance dead right.

[Ahmotorsport]

Nice thread. Still find it weird about the small end bushes and in the pictures don't look steel backed but alright xD

 

Also, as an add on you can buy Wossner Zetec Turbo pistons now.

Edited September 17, 2012 by Ahmotorsport

[Stu]

Also, as an add on you can buy Wossner Zetec Turbo pistons now.

 

You've been able to buy Wossner pistons for the Zetec for several years, I used to be a reseller but the distributor was pretty useless so I dropped them. They used to do them for the 1.8 too, which is a preferable engine to turbocharge.

Edited September 17, 2012 by Stu

[bongo]

why is the 1.8 better stu? would have thought the 2.0 would be better because of the cooloing jets.

[Stu]

why is the 1.8 better stu? would have thought the 2.0 would be better because of the cooloing jets.

 

You can have the under-piston jets on the 1.8 too (130ps have them as standard).

 

The 1.8 is technically superior because it has thicker cylinder walls and it is not a siamesed block like the 2.0 is. This means the coolant flows around more of the cylinders on the 1.8 compared to the 2.0.

 

However, I have never seen a 2.0 zetec block fail due to poor cooling, so it's a bit of a moot point! Just being pedantic. Once upon a time I considered building a custom short-stroke 1.8 zetec (to give 1.6 litre) with the intention of rev'ing to 10k rpm.