Technical Seicento 1.1 SPI second injection

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Technical Seicento 1.1 SPI second injection


New member
Nov 27, 2021
Hello all,

This is my first post on this forum after doing so much research on turboing the seicento. Recently i put a 1.4 uno turbo on my seicento without any other upgrades. the issue I am having now is fuel. I read that you can install a second injector and regulate that with a mf2 or det3 controller. The problem now is that I can't seem to find how to install this second injector, i have searched the forums but can't find anything. I'm hoping with this way I can get some advice on how to start doing this. My engine is the stock 1.1 spi (176b2000) with uno turbo. Would it also be possible to replace the existing injector with a better one? Also what thickness would be required for the stronger HG im guessing close to 2mm? and the thickness for the decompression plate.

Edit: If anyone has a Van Aaken second injector adaptor or anything related to parts for a seicento turbo (stronger HG, pistons, rods, cam etc..) please do let me know as I am interested.
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Are you still on with this?

Sounds interesting!

The Van Aaken kit used an MF2 controller with an internal pressure sensor (don't think all of the MF2's had one) which controlled a green Bosch injector (450 ccm I think).

The injector was housed in a 'top hat' which sat on top of the throttle body and held the injector roughly 45 Degrees from the opening about 10 cm above the original injector. If you are half decent at fabrication you could make one, the only critical dimension is the width of the throttle body. If there's a 90 Degree elbow in reinforced silicon tubing, you've got the start of your adapter right there!

The Van Aaken kit changed the way that the original injector interacted with the engine while running because it also installed a Voltage clamp on the MAP sensor. Because the inlet manifold would see positive pressure when the turbo spooled it would kick the original ECU in a strange direction (I guess it would go in to error). The clamp allowed the MAP to report negative pressure ranges OK but stopped it from reporting negative pressures. I guess it kept the dash board happy. My point with this is that the original injector isn't doing a lot of the hard work any more, I guess it's more an idle injector and low RPM (although the MF2/Bosch can take care of all of the RPM range to be honest, if it were required)

Upgrading the existing injector instead of using a second injector and controller would be quite a task as I understand it for 2 reasons - one, the form factor doesn't give you a lot of choices if it were to sit in the throttle body housing. Two, to make the single injector fuel correctly through boost would be a custom remap or maybe not possible with the original ECU and MAP sensor. You'd need to at least get a MAP sensor which could measure both the negative pressure and positive pressure and then map the fueling to this new sensor output. As with everything, not impossible, but you're in the realms of a complete ECU change.

Thickness of the decompression plate depends on what compression ratio you want which will be determined by what kind of boost you expect to be running. As I understand it you can run up to 0.4 bar with stock CR and no intercooler, so depending on your wishes you may not need it. Otherwise I'm aiming for about 8.5:1 and an intercooler and would be willing to turn it up to 1 bar (but that's not based on science, just other people's research, let's find out).

It's small, but a decompression plate will play with your cam timing. It could be like 0.3 of a tooth misalignment considering the pitch of the teeth which may be considerable without Vernier pulley. If your head hasn't been massively skimmed, you can take some material out of your chambers or skim some off the pistons (or both) and not use a decompression plate. I may be worrying too much about decomp plate and timing, I'm sure others have used them with no problems.
It looks like an 8.5 mm pitch on the cam belt which means that a 2 mm plate would effectively 'jump' the belt a quarter of a tooth. Would it do anything untoward, I don't know, my pulley is in degreaser right now so I can't calculate the angular impact 😂