Boost control on the 8v 2L turbo

[cthulhu]

How sophisticated is the boost control logic in the ECUs on these things? Will it trigger a fault if I plumb a bleed valve into the boost line going to the wastegate actuator? What about if I bypass the boost control solonoid completely and do my own boost control?

Thanks in advance.

[mjb]

A non-functioning turbo doesn't throw up the engine management light if that's what you mean

[cthulhu]

A non-functioning turbo doesn't throw up the engine management light if that's what you mean

No, that's not what I mean. I want to increase boost pressure but want to know if the ECU is going to get upset if I override its boost control.

[mjb]

Pretty sure a few people have run turbos at higher pressures. But you should be aware that there appears to be a VERY high failure rate of these turbos which have been run outside the factory setup

[mikey s]

your limited to 1 bar of boost as there is only a 2 bar map sensor in the ecu. it will be like hitting a brick wall when the ecu reaches its max capacity. they can be run at about 12 psi quite reliably but the turbo runs quite a small and inefficent compressor. better gains can be had by replacing the turbo and manifold. the 205 tt manifold and a t28 from a pulsar/200sx would be a very good upgrade for the 406, would deliver more power than the stock setup running the same boost pressure.

just remember, the xu10j2te engine was never designed to be a fire breathing animal, it was designed for torque low down and it does that very well.

[cthulhu]

Thanks mikey, that's very useful. I was only looking for a mild boost increase anyway on the stock pistons. I want to fit an afr gauge before I start messing with boost, just to be safe.

I've been lead to believe (by the local peugeot dealership) that the XU10J2 and XU10J4 motors essentially share the same block and the heads are interchangeable, except for the water pump which will need to be replaced with an electric item. Anyone on here done such a conversion or know more about this? I'd have thought a set of heads from the 306 S16 would be a nice breathing improvement, even if the cam profile wasn't ground with a turbo in mind.

[mikey s]

Thanks mikey, that's very useful. I was only looking for a mild boost increase anyway on the stock pistons. I want to fit an afr gauge before I start messing with boost, just to be safe.

I've been lead to believe (by the local peugeot dealership) that the XU10J2 and XU10J4 motors essentially share the same block and the heads are interchangeable, except for the water pump which will need to be replaced with an electric item. Anyone on here done such a conversion or know more about this? I'd have thought a set of heads from the 306 S16 would be a nice breathing improvement, even if the cam profile wasn't ground with a turbo in mind.

theres nothing really wrong with the stock bottom end. some guys in sweden are running circa 300bhp on stock bottom ends and using the cars for track days! if it starts going weak invest in rising rate fuel pressure regulator, its a crude way of doing things but it could save the pistons.

the bottom ends are the same. if you want to run a 16v head on an 8v bottom end you will need to do 2 things. firstly, the pistons will need pocketing to accomodate the valves and secondly, you will need to drill and tap the block to accomodate the second tensioner that the 16v engine uses.

effectively, mating the s16 heads to the 8v bottom end would create a t16 lump.

[cthulhu]

theres nothing really wrong with the stock bottom end. some guys in sweden are running circa 300bhp on stock bottom ends and using the cars for track days! if it starts going weak invest in rising rate fuel pressure regulator, its a crude way of doing things but it could save the pistons.

AFR gauge is going in this weekend, but I hope to pick up a proper wide-band controller in the near future, then look at outright after-market management with a megasquirt or something before I get too crazy.. £££ permitting. Glad to hear the engine's aren't as weak as I'd heard. What about the top end though? Any idea what the valve springs are rated to?

the bottom ends are the same. if you want to run a 16v head on an 8v bottom end you will need to do 2 things. firstly, the pistons will need pocketing to accomodate the valves and secondly, you will need to drill and tap the block to accomodate the second tensioner that the 16v engine uses.

I've come to learn the 16v head has individual exhaust ports for each valve so that means a new exhaust manifold into the bargain as well. Sounds like more hassle than its worth.

Next question.. you mention changing the turbo. I guess a T28 (as you say) or maybe a TD04 would be a good match, but will they just bolt up or am I going to need an adapter place or (god forbid) a new manifold? For that matter, what is the turbo on the 406?

Thanks mikey - you're champ.

[mikey s]

the standard turbo is a t25. the t28 will bolt straight onto the t25 flange. im unsure what flange the tdo4 uses but it maybe getting on to be abit to big to slip down the back in a 406.

[cthulhu]

the standard turbo is a t25. the t28 will bolt straight onto the t25 flange. im unsure what flange the tdo4 uses but it maybe getting on to be abit to big to slip down the back in a 406.

Oh wow, I didn't realise the factory turbo was a garrett. Cheers for that. Almost a shame really, though. The WRX are always upgrading their turbos so the TD04s are a dime a dozen.