126 Progress log - 126 1.1 8v FIRE with a Van Aaken turbo kit


Hello Fiat forum,

I have a 126 with a 1.1 FIRE in which is fine for what I need, motorway is no bother and it's a bit of fun around the countryside, but last year a Van Aaken kit came up on eBay and I was clearly on a mad one because I ended up buying it. I thought I'd see the summer out enjoying it NA and get the kit installed over the colder months, which is now!

I intend to drive it often, commute etc so I'm trying to make it as reliable as possible, oil cooler, reduced compression ratio, intercooler as well as maybe some less well founded (?!) stuff like polishing the combustion chambers to reduce knocking. I guess while it's all in bits, I may as well. I'd like to have the confidence in the build to turn the boost up if wanted.

We know this engine wasn't meant to be turbo'd and I don't have unlimited budget so I'm trying all I can to get full enjoyment from it for as long as possible. I'm no expert but YouTube has made me believe in myself to maybe extreme levels :rolleyes:. I have a modest workshop so I can do a bit of this myself.

Today was engine out day, only a bit of rain so no complaints.


The plan in a rough order is:

  • Polish and cc combustion chambers
  • Strip down bottom end and inspect bores/crank/pistons - hopefully all will be in good shape, I expect to have to get new rings but these aren't ordered yet, don't know which size I may need depending on bore wear. Interested to hear what you'd gap these at.
  • Fit any new bearings and seals identified as bad along the way, inspection points will be end float, big end bearings and seals
  • Turbo oil feed from upper tap of oil pump/filter housing. This takeoff was included in the kit but it doesn't seem restrictive as much as I have seen on other turbo feeds, any advice on what kind of restrictor I need would be much appreciated
  • Turbo oil drain fitted to new sump, above oil level
  • Reduce compression ratio to about 8.5:1. My preferred option would be to skim the pistons but I'd need to do some measurements on them first to see what I'd be left with! Second option is work the heads pre-polish and last option is a compression plate. I don't fancy the plate because it's the most expensive option and I don't want to mess with the valve timing.
  • Install the thermostatic Mopar oil takeoff (filter sandwich type) and radiator
  • Find somewhere to mount an intercooler - thinking of making a shroud that will duct air over it picked up from under the car, or from one of the side vents, with the oil cooler behind it
  • Make an exhaust up - bearing in mind that I want it to be a useable car and it's very noisy right now, I'd like to quieten it down a lot. The previous owner was frugal yet smart and used a mid box from the donor car (Sei). Any suggestions on a decent backbox which isn't huge would be greatly appreciated
  • Clean and paint a few bits on the engine, I don't want a show car engine but it would be nice to have something that looks better than when it was pulled out. Why not ey?!
  • Blow up the stock gearbox
This is a learning experience more than using what I already know, so if you have some tips please let me know.

I'll keep updating this thread as I go.
A few days later, a few more bits taken off the block and inspected/cleaned/stored.

The block as it stands (waiting bolts to mount it to the engine stand):


The collected parts:


If the part isn't in one of these two pictures it's in the tub of degreaser, which is slowly eating all the aluminium parts... I should really take those out.

Looking at the bores, all surfaces look like this:


Which look quite good, original(?) hone marks all still there with no visible damage. When the pistons are out there will be a quick multi point measurement of the bores to see if they are as good as I need.

The head is being replaced with a reconditioned one - I'm not equipped to deal with the head work and testing.

Next step is to get the block on to the stand, get the crank out and take a look at the bearing surfaces and measure up for rings and bearings. Probably paint a few bits too.

Away from the engine, I need to set up the instrumentation in the car. I have an AFR, RPM and boost gauge to install, thinking about where the radio would normally go (no chance of hearing that anyway). The issue is routing the wiring. In my haste to insulate and carpet, I didn't leave a flap along the nearside footwell to allow for any further wire runs to be added. Tempted to penetrate above the bell housing of the gearbox (there's a ~150 mm square panel that can be removed/modified) and run the wires along the centre console...

Also need to work out the oil feed to the turbo - the feed line I was supplied looks to be oil tight but it's been around the block. It also doesn't seem to have a restrictor in. If anyone knows, what thread size is the filtered take off from the oil pump housing? I did search here and google it up but no luck. What size restrictor would you fit in line between the pump and the turbo? I have seen 0.9 mm being a very common size. This is a T15.

For what it's worth on the restrictor, Garrett reckon 40 thou orifice will do unless exceptional circumstances, which I don't think I'm in here...

A little further on, checked the main bearings which are in tolerance, on the loose end. Nice an even throughout. I'll keep them in.


I had spent a bit of time measuring all the constituent parts of the compression ratio calculation, did a rudimentary combustion chamber measure with some acrylic and a syringe. The head had been skimmed and the chambers came out even at 20.9 ccm.


The combustion chambers were also cleaned up and polished/sharp edges knocked off.

Knowing everything I was able to plug the numbers in to a calculator



I simulated taking off 2.4 mm using the piston to deck clearance. I then took off 2.4 mm


This is about half of final depth of cut, I was taking off about 0.8 mm a pass. The 2.4 mm takes off all shaping and makes it a completely flat piston. This was not an ideal setup and took a bit of dialling in, but I don't have tall jaws and I really didn't want to take the pins out of the piston/conrod assembly.

I saw somewhere that VA suggested 'a couple of mm' when asked how much they take off a piston for their high boost kit. As this head is skimmed and that I wanted to reduce the CR quite a bit, that seems about right.

Next job is to get the new rings in, bolt the bottom end back together, sort out the turbo drain in the (new) sump and work out how to fit the intercooler in there...