Alternative XU9 +T

[TomSaintJames 1]

Morning everyone, I've been enjoying the content of this forum for a little while now for research and planning purposes, and may I say what a fab palce this is with awesome knowledge and wisdom. Now it is time to really start considering my project as I near finishing the curent one - well, finishing it enough to be returned to use! Just for your info, I'm currently building a Volvo 740 with a previously standard bosch LH2.4 managed 2.3 940 turbo engine, but now with a few tasty upgrades! Including a hybrid turbo. The Volvo is the first time I have ever messed around with anything more in-depth than general maintenance, I used a complete 940 loom and 940 dashboard (mostly for the a/c but also other EFI reasons) which is what is taking time my time now - getting the 740 body wiring and 940 loom to match up - i'm nearly there!

 

Anyway, onto the XU9. I have a very rare and early BX GT with a carburetted 1.9. It had a new Solex 34/34 Z1 carb at the beginning of the year as the previous (original) Solex CISAC had worn beyond repair. I gave it to an official weber/solex dealer and had it rolling road tuned and re-jetted (it has a custom stainless 2.25" twin exit exhaust) but I've never been happy with it, the original CISAC which is an early version of the Z1 was just better. So, for this and general ease of use I want to go EFI - BUT due to the rarity of the car I don't want to just fit a BX GTI injection system to it, then it'll just be another GTI - the carburettor engine is what makes this particular model so rare,

 

It currently has 81bhp at the wheels, but only at 4600 rpm and 151 NM at 2700rpm - so power is down but torque is close albeit at a lower rpm. Factory sepcs for the 159A engine are 105bhp @ 5600 and 158NM @ 3000 AFAIK.

The plan is to use a throttle body kit from Webcon, as per the link below it directly replaces a weber DGV and is comptaible with a DMTL but needs  a slight mounting bolt adjustment, XU9 BXs (particularly auto's) did come with a DMTL so happy days, it looks like a carb which fits with my image/plan for this car. The only downside is the price, but as I can't really start this project until next year sometime there is time to save up. What I want from the car is not huge power, around 145bhp would be great but ease of use and an increase in torque is what I really want. For perspective, we went out for dinner the other day and going up a steep hill on the motorway I was flat out in 5th, which is too noisy with the sexy exhaust when your trying to chat with friends in the back! So a boost in torque and a turbo to slightly quieten the zorst is what I want. A quieter exhaust is the thing i've sold tothe OH to partly justify the project , we also use the BX to travel to it's homeland - France, so quieter and smoother FTW. I would probably want to fit a TD gearbox for lower motorway rpm's, as an aside when it's just me I really like the noise, but it is a multi-purpose vehicle.

 

Webcon retroject throttle body with integral sensors as per this link

If you scroll down the kit pretty much contains everything needed for an EFI conversion, the Maxxecu mini has a MAP sensor and is turbo compatible upto 1 bar of boost, which is great. I plan to initially keep the current distributor ignition, unless this is unwise.

 

So for collecting parts, from my research I have got the following list:

 

-XU10 turbo or possibly Turbotechnics exhaust manifold (i'm watching one on ebay, but £450 ish!)

-TD04-13C turbo with either a LPT 4psi wastegate or 8psi HPT- my reasoning for using this is that its a very quick spooling turbo and the Volvo boys frequently ditch them for upgrades, so I have been offered a choice of two for free (LPT/HPT).  I also believe it'll fit the T25 flange. I hope that the coolant and oil feed/returns from the 13C can be adapted or modified for the XU9. There is an oil pressure sensor in the block by where the turbo would sit, supply may be more tricky.

-Possibly DFZ head

-Possibly DKZ cam

-Possibly a BX TD intercooler that sits above the engine, I can then use the standard TD pipework and underbonnet scoop.

-The current air flter box should be compatible as the intake faces the area under the distributor, i'm sure the TD boost pipes can be adapted here.

 

Naturally I have some questions for the wise amongst us!

 

1. Compression ratio, pinking and head choice. My current engine is 9.3:1, I think it has the flat topped pistons based on research (not evidence) but unsure of the head I have other than i think it'll likely have the smaller valves. My Volvo buddies love the idea of this project and said just +T it at 9.3:1 and only worry about ignition control if it pinks under boost, especially as I only plan on either 4 or 8PSI. I know my valve clearances are out (too large), the cambelt snapped when I first bought the car but only at starter motor speed (it had been off the road for 16 years). Although it runs pretty well, I think it wise to have the head off to check and install an upgraded HG.

If I am having the head off anyway, should I get a DFZ head so that the CR is of no worry? Or would it perform generally better (ie off boost) with the original head? Ideally i'd leave the bottom end alone unless there is damage - which I think unlikely.

 

2. Exhaust manifold. Finding a standard XU10 turbo manifold would be the budget choice, however I have read how restrictive they are. With my want of no lag and a low boost application - would it be worth me spending £450 odd on the currently for sale turbotechnics manifold? I plan on getting the guy who did my downpipe-back stainless system to make me a new downpipe, so this is not a worry.

 

3. Cam choice. I am assuming my current cam is pretty mild, I know to avoid the 130bhp cam for a turbo application due to excess inlet (11.3 lift)/exhaust (11.3 lift) valve overlap so a mid-ground upgrade would be the 122bhp option which I have down as DKZ. Is this also a BX GTI cam? I want to avoid a TD like power output and be able to have a decent power spread over the whole rev range but not at the sacrifice of low-end drivability.

 

4. Intercooler. Finding a BX TD system should be easy and I think it should all fit with little modification, but having the intercooler above the engine is obviously not the ideal choice. Sierra cosworth intercoolers are frequently mentioned, in my BX I have twin fans, then a/c condesnor and then the radiator - there is no space for an intercooler infront of the fans, but possibly room for a small one (about 6 inches) in the lower bumper/grill area.-Having it out of sight would be ideal but tricky - routing the boost pipes would be a challenge and they'd be quite long.

 

5. PCV system, I'm not really sure of this but expect i'll need to look into it to avoid sludging or other excessive crank pressure issues.

 

I'd appreciate your thoughts and wisdom! I'm quite excited about the project and can't wait to start hoarding and planning in earnest.

 

This is the RR directly post-rejetting

 

 

Edited November 1, 2023 by TomSaintJames

[Tom Fenton 1,525]

The 2.0 8v turbo manifold will bolt straight onto the head, however the flange from manifold to turbo is a specific triangular shape thing, that only the specific T25 turbo intended for the manifold will fit. For what you describe it will not be overly restrictive, it can make over 200bhp. For ease of fitment that is the way I would go, i.e. a complete manifold and turbo from a 2.0 8v turbo. In my opinion you are making life hard with the carburettor requirement, but that is your choice. 

Cam and engine internals I'd personally leave alone, as again for 145bhp will probably do the job in hand. You will definitely need to do something with ignition management though, even the turbo technics cars which by modern standards are pretty crude, recognised the need to retard ignition timing with boost pressure.

The GTI cam works well in turbo applications despite what the internet might think, low overlap cams are great for an engine that is all out of puff by 4500rpm, the GTI cam if the turbo is up to the job will produce power all the way to near 7000rpm.

I own and have worked on a few turobcharged XU 8v so this is all from experience. 1580 8v turbo 204bhp, and a 1905 8v turbo 252bhp are 2 that spring to mind.

[TomSaintJames 1]

Thanks for the reply Tom, I was hoping you would reply! As you've said you have direct experience which is awesome.

 

I'm glad to not have to change many engine parts, i'll get my current head tested and cleaned. Is it worth getting the three angle valve flow job i've read about done? It sounds worth my while upgrading the cam. I see your 1.9T XU has 252bhp! That is very cool.

 

I'll look into ignition management, it will be good to have that sorted too.

 

Cheers.

[SRDT 146]

Tom is right about the turbo and the ignition.

I think your 159A head is close if not the same than a DFZ one. Too bad that you can't use a "big valves" head with your flat pistons.

You can find more info about the 159A, DFZ and DKZ engines inside this big .pdf :

http://www.ckc.dk/pubs/MAN008890.pdf

It's in French but it's all about the BX.

 

The diesel top mount intercooler has the outlet pointing in the wrong direction for a petrol engine so there is some plumbing to do.

 

The BX td gearbox doesn't have the best ratios, there is a sensible gap between 2 and 3. A 205 td gearbox has closer ratios but a longer final drive and is often a better compromise. Or you could try to fit a 6 speed gearbox from a 306 GTI6.

[Tom Fenton 1,525]

I personally wouldn't do the 3 angle valve seat. The turbo will make the valves run hotter, you want a nice wide seat to help take the heat away. On a NA engine all the flow you can get helps, on a turbo engine of course it helps, but its not as critical as you have the boost pushing charge in and to some degree out. Easier performance is increase boost pressure say 1 psi than the effort of 3 angle seats.

[TomSaintJames 1]

Awesome replies guys, thanks! It'll be very interesting to see how this turns out, it'd be great to be able to keep up with a BX 16v - although i have no idea if 160bhp might be ambitious or easily attainable.

Edited November 2, 2023 by TomSaintJames

[Tom Fenton 1,525]

TBH very easy if you fit injection and a proper ECU. Even at an equivalent 160bhp you would have significantly more torque than the NA 16v engine. 200bhp really is not difficult from 1905cc.

[TomSaintJames 1]

Great, as per the link in my 1st post - I'll be fitting that carb lookalike twin injector throttle body with ECU and all the sensors.

I'm guessing the internals can take the extra power etc if the management is properly set up?

 

My thoughts entirely, I've been in a few 16v BXs and whilst they are rapid, it's all top end. They sound great too I've noticed XU petrol have a fairly distinctive sound.

Edited November 2, 2023 by TomSaintJames

[SRDT 146]

Peugeot Talbot Sport had a turbo kit for the 309 GTI : 165hp @ 6000rpm and 24 m.kg @ 3000rpm. The 309 16v is behind except at low speeds but the turbo could probably beat it with the same tyres and suspension.

The XU10J2TE (2.0 8v turbo) has special exhaust valves for the heat but they should not fit as is on your 159A head. The turbo kit has sodium filled valves, maybe overkill for 165hp but they borrowed them from the close-to-200hp racing version.

[Tom Fenton 1,525]

20 hours ago, TomSaintJames said:

Great, as per the link in my 1st post - I'll be fitting that carb lookalike twin injector throttle body with ECU and all the sensors.

I'm guessing the internals can take the extra power etc if the management is properly set up?

 

My thoughts entirely, I've been in a few 16v BXs and whilst they are rapid, it's all top end. They sound great too I've noticed XU petrol have a fairly distinctive sound.

You are making yourself issues in my opinion, wet tract injection on the standard inlet may well give charge bias under boost leading to some cylinders richer or leaner than others. Probably also poor idle running and transition. Port injection easy to implement and none of these issues. I have never understood people fitting this or not fitting that because of what someone else will think or what it "makes it". Especially when its going to give you a headache. Its your car however so do what you want, you can always put it back if it comes to it.

[Tom Fenton 1,525]

10 hours ago, SRDT said:

Peugeot Talbot Sport had a turbo kit for the 309 GTI : 165hp @ 6000rpm and 24 m.kg @ 3000rpm. The 309 16v is behind except at low speeds but the turbo could probably beat it with the same tyres and suspension.

The XU10J2TE (2.0 8v turbo) has special exhaust valves for the heat but they should not fit as is on your 159A head. The turbo kit has sodium filled valves, maybe overkill for 165hp but they borrowed them from the close-to-200hp racing version.

Standard exhaust valves I have found to be OK at 18psi.

[SRDT 146]

This is how Peugeot took oil for the turbo on the race engine, the PCV system isn't the same than the street engine.

[petert 550]

On 11/2/2023 at 9:50 PM, Tom Fenton said:

I personally wouldn't do the 3 angle valve seat. The turbo will make the valves run hotter, you want a nice wide seat to help take the heat away. On a NA engine all the flow you can get helps, on a turbo engine of course it helps, but its not as critical as you have the boost pushing charge in and to some degree out. Easier performance is increase boost pressure say 1 psi than the effort of 3 angle seats.

An interesting point of view when you can make the seat as wide as you want with a modern CNC single point seat cutter, which cleans up into the bowl as well. I'd much prefer to make the hp with volumetric efficiency rather than winding up the boost and making unnecessary heat. Effort? If your head place is cutting seats by hand, you're at the wrong place. CNC seat cutting is fast and efficient. My place stores my favourite profiles as a CAD file and just calls up what I want.

Edited November 4, 2023 by petert

[Tom Fenton 1,525]

6 hours ago, petert said:

An interesting point of view when you can make the seat as wide as you want with a modern CNC single point seat cutter, which cleans up into the bowl as well. I'd much prefer to make the hp with volumetric efficiency rather than winding up the boost and making unnecessary heat. Effort? If your head place is cutting seats by hand, you're at the wrong place. CNC seat cutting is fast and efficient. My place stores my favourite profiles as a CAD file and just calls up what I want.

 

 

As with anything context is important, in context of you building a race engine wanting every last hp with assumedly a good budget to do so then of course you'd do all of the above. In the context of me strapping a turbo on an otherwise standard internally XU5 engine, no I didn't have the seats modified as for a car to mess about with on the road I didn't forsee the bang for the buck that would be required.

Maybe best summed up as the difference between the best it can be, versus good enough for the job.

[SRDT 146]

If you want/need to work on the small valve head maybe it's time to consider using another one.

Could XU7JP or XU7JP4 pistons make a turbo friendly C.R. with a big valves head?

[TomSaintJames 1]

Some really interesting replies here gents, thank you!

 

Going back the the wet liner, non-identical inlet runner thing - now you mention it what you say Tom makes perfect sense, even with the current standard setup the centre two spark plugs are blacker than the outer two - but it was something I was ignorant of until now!

To combat this, a standard 205 inlet mani, TB and fuel rail would probably be the easiest solution I guess? All the BX injection stuff uses round ports, but my carb head has the Cathedral shaped ports like 205's.

[TomSaintJames 1]

23 hours ago, SRDT said:

This is how Peugeot took oil for the turbo on the race engine, the PCV system isn't the same than the street engine.

This is great, thanks dude. Saved!

[TomSaintJames 1]

3 hours ago, SRDT said:

If you want/need to work on the small valve head maybe it's time to consider using another one.

Could XU7JP or XU7JP4 pistons make a turbo friendly C.R. with a big valves head?

If I can get an easy, affordable and efficient extra 50hp with a dollop of extra low end torque - thats pretty much all I want/need. I don't really want to get into the block unless I have to either (apart from oil drain/feed of course), that's a bit more of a project than I want.

 

So I may be messaging petert about a bit of light head work! The shop over used before is very good, but properly old fashioned.

[petert 550]

I fitted my first 205 race car with a DFZ (1.9L, small valves). You could definitely tell the difference between tractor seats and 3 angle seats, with no other mods. I wouldn't hesitate to run the small valve head. I'd also make sure it has at least 90lbs on the seat, if boosting. This can usually be accomplished by adding a 2nd shim under the valve spring.