Engine

Description - Spec -  First Mod - Boost Control - Dump Valves - Further Development

ANY MODIFICATIONS YOU MAKE TO YOUR CAR ARE AT YOUR OWN RISK!

Description The Lancia Y10 turbo uses the 1049cc Fiat Brazil engine with the addition of an IHI RHB5 turbo and Weber 30/32 DMTR twin choke carb. It also uses the Digiplex ignition system to retard the ignition under boost conditions. In general the engine works very well in standard form and much fun can be had, but if your here, you want more... As with all engines, to improve power you must increase the amount of air/fuel going in and enable the exhaust gases to get out easily, without restriction. With the Y10 turbo we can do this in a number of different ways, as we have a turbo the easiest method is of course to increase the boost pressure and re-jet the carb to meet the fueling requirements, this can give very good results, most seam to make around 120bhp with increased boost pressure, fueling (and in most cases a free flow air filter and exhaust), with no other internal engine modifications! Of course this engine will also respond well to "normal" tuning methods, "flowing" the head etc ( The 1049cc engine in non-turbo form can produce 100bhp+ as seen in a number of 127 racers). There would be very little point in me going into detail regarding internal engine modifications (as I know little!) but a few points should be considered when having this sort of work done. The engine uses has a 7:1 compression ratio, if you having head work done make sure the head is not skimmed too much as this will raise the compression ratio (and increase the chance of detonation). As mentioned, the Fiat 127 uses the same engine, and the 1050 and 1301 sport models have good (read lumpy) cams which work well in the Y10. Piper cams have also produced a very "hot" cam profile specifically for the Y10 turbo (as fitted to Peter Dietsch's Y10!), not really ideal for every day driving though as power arrives at around 4000rpm with a BANG! A good quality head gasket is obviously a good idea when upping the boost! If you decide to modify your engine, try to change the oil more frequently, if your constantly giving the engine a hard time oil changes as often as every 3000 Miles might make it last a little longer (especially the turbo). Give the engine time to "catch its breath" for a couple of minutes after a hard drive, this will allow the turbo and exhaust manifold to cool and might prevent the oil "cooking" in the turbo and destroying the bearings.

First Mod

The first modification that any Y10 turbo owner should consider is the removal of the intercooler bypass valve (fig 1) and pipework. This valve is intended to improve cold running by redirecting the compressed charge air to bypass the intercooler, well, that's the theory! In practice this valve just serves as an obstruction, in some cases the wax thermostat that opens the valve will stick, this means the charge will never see the intercooler no matter how hot the air gets, not good for power...
In fig 1 On the right you can see the bypass valve (1) and the lower T-pipe(2).		1.
To remove this valve from the system simply replace the top and bottom sections of pipe work with straight pipe of the same diameter, depending on the age of your Y10 the lower pipework may or may not be exactly as shown.
Your pipework should then look something like fig 2.		2.

Boost Control

Increasing the boost pressure should ALWAYS be accompanied by improved charge cooling and additional fueling, serious engine damage could result from an improperly tuned system.
ANY MODIFICATIONS YOU MAKE TO YOUR CAR ARE AT YOUR OWN RISK!

The Y10 turbo, like most factory turbo cars, uses an internal wastegate built in to the turbo housing to control boost pressure, the wastegate is a valve that allows the exhaust gases to escape into the exhaust without passing through the turbo's exhaust turbine, the more the valve opens the more exhaust gas is allowed to escape, controlling how much pressure is generated by the turbo.

This valve is controlled by an actuator, the actuator is pressurised by the turbo outlet and this acts against an internal spring to move an arm connected to the wastegate, boost pressure is set by the strength of the spring, once the boost pressure overcomes the resistance presented by the spring the wastegate will open, allowing the exhaust gas to escape.

There are a veriety of ways to control this process, we could use a stronger spring so more boost pressure is required to open the wastegate, or we could reduce the pressure the actuator will see, this is the most common method, to do this we can introduce a controlled leak into the wastegate pressure signal line, most often referred to as a "bleed valve" this is the method I will describe below...

Fitting
Locate the wastegate pressure signal line, depending on your dexterity you may have to remove the radiator but you should be able to see it by getting your head under the front of the car and removing the turbo outlet/intercooler pipework, the line you are looking for is shown in the image below (this turbo was lying around in my shed, you don't have to remove it for this job)..

small, rubber,and quite innocent looking.

Remove the rubber hose from both ends and replace with two longer sections of hose, secure with jubilee clips at both ends (fuel hose will do) ideally we should be able to adjust the valve from under the bonnet so each pipe should be long enough to reach a convenient place in the engine bay to mount the bleed valve (although the shorter the path the better).

Install the bleed valve between the two pipes and secure in the engine bay, again secure with jubilee clips at each side also make sure that there are no kinks in the hose as this will block the line.

Start the car with the bleed valve completely closed, the car should function exactly as it did before (although if the signal lines are too long you may experience "boost creep", this is where the boost pressure rises over the required level for a short time under high load as the air in the lines takes time to be compressed, this can be used in positive way, see Autospeed for more details!!.

Open the valve a small (very small!) amount and drive the car to see what effect it has on the boost pressure, repeat this process until the required boost level is reached, always move up in small steps so you have a chance to detect any problems.

If you want to exceed 0.86 bar you will have to bypass the maximum pressure switch, this is located on the inlet manifold to the right of the carb, you will see a black rubber boot with two brown wires entering it, remove the boot and disconnect the wires from the switch, and join them together. Insulate this connection!! shorting to earth can cause serious problems and a burnt out loom!!
Once you have done this the engine is left without protection so be very careful with your boost pressure!

You will know when you hit the maximum boost set by the pressure switch as the fuel supply will be cut resulting in a huge bang and a big black chuff from the exhaust!

I would advise a rolling road tune after the fitting of a bleed valve, if you are forcing more air into the combustion chamber you must also add fuel, if the engine is allowed to run without additional fuel you run the risk of a lean mixture, which could cause detonation and the end of your engine...and you can't buy Y10 turbo pistons any more so be careful! you have been warned!

I highly recommend the boost control device described in the Autospeed article "Audi Boost Control", this allows adjustment of not only boost pressure level but also the rate at which this boost is developed!!

Dump Valves
The standard Y10 turbo has a "dump" or "compressor bypass" valve located next to the turbocharger outlet, this valve releases the unwanted compressed air in the intake system when the throttle is released. You can use this valve in the standard location to get the pleasing "ptsss" dump valve sound by simply unplugging the outlet of the valve (the and blocking the hole in the inlet pipe)...I would not recommend this however...when the engine is running with the throttle closed the vacuum in the inlet manifold will cause the dump valve to open, with the valve located so close to the ground there is a risk the engine could induct dirt / dust from the road surface.

The best method I have found is to replace the turbo outlet elbow with a 90° Hose, then mount the dump valve on T-piece where the intercooler bypass box was originally located, this kills two birds with one stone, the bottom elbow (known for it's weakness) is replaced and the dump valve is positioned closer to the throttle body and after the intercooler for improved turbo response.

I Now Offer a Kit to remove the intercooler bypass valve and relocate the dump valve for better performance, everything is included in the kit and you can now purchase online in the Shop

Further Development
Fuel Injection etc coming soon...