XUD tuning - XUD9 n/a cam in XUD7TE?

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nametooshort
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XUD tuning - XUD9 n/a cam in XUD7TE?

Post by nametooshort » 24 Nov 2014, 19:49

Good morning people.

So, I seem to be seeing a lot of references to people putting the cam from a non-turbo XUD9 into a XUD7 turbo, treating the 9 n/a cam almost as a hotter cam upgrade for the 7 turbo.

We kinda started messing with various XUDs and came up with a couple of really tuned examples, I figured I would test the theory that the 7 is actually the most potent (potentially) member of the XUD family, despite being the smallest. The one on the bench now is running a heavily ported head, custom manifolds, a hybrid turbo, hybrid injection pump and some other stuff. Its running 1.1 bar of boost dry or 1.6 with meth injection, and its holding up really well. But on a stock cam cause aint nobody seem to make hot cams for XUDs.

So anyways, what IS this whole thing about of camming a 7 turbo by using a 9n/a cam? Is there a lot of benefit to it? What exactly does it achieve? And is it just any cam from a 1.9d or are there specific variants? Can anybody explain?

Thanks.

MikeT
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Re: XUD tuning - XUD9 n/a cam in XUD7TE?

Post by MikeT » 24 Nov 2014, 21:45

Subscribing with interest 8-)

Can't offer any insight into the cam change but interested to know what gains (hopefully) it'll bring you. Also want to be nosey at what prompted the alcohol injection addition, are you monitoring EGTs?

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Re: XUD tuning - XUD9 n/a cam in XUD7TE?

Post by RichardW » 24 Nov 2014, 22:17

The N/A cam has a higher lift and longer duration than the turbo cam, so sticking it in will give more time to get air in there, without having to increase the boost pressure. The original Haynes book for the XUD engine helpfully gives the cam timings and durations so you can compare!

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nametooshort
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Re: XUD tuning - XUD9 n/a cam in XUD7TE?

Post by nametooshort » 24 Nov 2014, 22:46

Meth injection keeps the EGTs down and the detonation threshold acceptable and makes it possible to run much higher boost levels than stock without killing the motor, while using stock pistons/compression ratio and a sensible size cooler. Without it, you would need a very huge and over-restrictive cooler and also the pistons would take a hammering and get damaged pretty quick, and also the head gasket probably won't last long.

The hybrid turbo starts pumping much faster than the stock one so its getting all this extra boost where the stock motor was still running in n/a mode.

The threshold (limited by sensible EGTs) for dry running is 1.1 bar or so, which is not much more than stock of 0.7 bar or so for the non cooled motor and 1.0 bar for the cooled setup (but remember this one is running a lot more breathing and fuel and therefore EGT is higher). But with alcohol, it spools up to the turbos limit of about 1.6 bar (its not a very big turbo, so it spools real quick tho) and its pretty gentle on the pistons and EGT is less than a stock motor being driven hard.

I have no idea what sort of performance gains this will give, but we doubled HP in Volkswagen motors using this kind of technique pretty easily. But of course its more about usable power than numbers on paper, you can have all the hp in the world, if its in the top 800rpm only it aint no use. I think in real life, this will translate into a typical lightweight front-drive pugcit totally smoking cars from the 2.5 commonrail category.

Basically I just wanted to see how far we can push a 7. The 7 is shorter stroke than the 9 and 11 and so more suited for tuning thats relevant to a small motor in a light weight car, or so I heard a lot of people say, so I decided to try it out. I wanted to see for myself if a hot 7 really is much better than any attempts to tune a 9 or 11.

Besides, HDi motors suck, these oldschool xuds seem to still hold their own when it comes to tuning. My buddy killed so many HDi 2.0s doing far less to them than this poor xud is subjected too. I can see why mechanics all unanimously hate HDi motors now, and most people consider them useless for tuning.

Ok, so that totally makes sense. When it comes to looking for a cam, does it have to be any specific version? Or just anything thats a 1.9 n/a. Don't some of them have adjustable angle sprockets and some don't, or something? Or did I imagine that?

If I am looking for the correct cam, is there anything else I should look out for apart from that its from a 1.9 n/a?

Thanks!

Northern_Mike

Re: XUD tuning - XUD9 n/a cam in XUD7TE?

Post by Northern_Mike » 25 Nov 2014, 00:16

nametooshort wrote: I can see why mechanics all unanimously hate HDi motors now, and most people consider them useless for tuning.
I have absolutely no idea where you get this incorrect information from. The common-rail tuning and remapping market is very much alive over this side of the pond and it's very easy (and cheap!) to get considerable gains reliably with comparatively little outlay when compared to old style tuning methods. For example, a proper rollong-road remap done by business that specialises in this kind of thing will release an extra 30bhp and a fair amount of torque from my 2.0HDi 90bhp motor -that's a 30% increase with no hardware changes needed for less than the cost of two tanks of fuel. If I were to bother fitting an intercooler, hybrid turbo and so on, bigger gains can be had. I've seen these engines running 160+bhp for very little. To say they're bad for tuning and hated by mechanics is simply wrong. The only reason a mechanic would hate the 2.0 8v HDi is that it's too reliable and not a good source of income..

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nametooshort
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Re: XUD tuning - XUD9 n/a cam in XUD7TE?

Post by nametooshort » 25 Nov 2014, 09:13

Ok, so HDis may be OK motors to drive, but from a tuning perspective they are hated because:

I don't touch HDis personally cause of all the bad rep they get, but basically the consensus seems to be that they are just a bit of a oops for PugCit. Like the old joke goes that back in the day in the 70s 80s and 90s, PugCit were the market leader in small diesel motors. Most companies either did not build a small diesel or used something awful by a 3rd party manufacturer, which probably had pushrods and made about 30hp, and the only serious competitor was Volkswagen with their 8v overhead cam motors, but they were waaaaay behind and were hella crude. So you had the ultimate car company, Volkswagen, basically get completely owned by a French brand. But then ironically the tables turned, the newer PD an then commonrail motors from Volkswagen just got better and better, and PugCit made the....HDi family. Oops.

And THEN, just to make matters worse, they decided that their home-grown disaster wasn't good enough, so they collaborated with like the worlds worst brand ever to make that Ford/PeuCit range of HDis, which kinda was like err guys what the hell you thinking? Thats like, take a bad engine, and collaborate with a company that still used a cast iron block and head pushrod motor in the 2000s in their smaller budget models, and gave us cars with absolutely impossible onboard electrical systems.

Seems to be that HDis are less reliable than all the other commonrail families out there (disregarding BMW motors which still have their inlet flaps fitted, but then again NOBODY runs BMWs with their stock inlet flaps still fitted). Sure you can get like 30% or something and you can remap them like any commonrail motor, but you can't tune them a lot, they just can't take it and fall apart.

The reason the XUD was so miraculous is because it was a small diesel capable of a big top end power if you messed with it. Most small diesels like the HDi family are designed for good power in the middle of their rpm band. That's why they have tiny turbos and very small inlet plumbing. If you look at HDi inlet ports, they are tiny, and with that horrible plastic combination cam cover and inlet manifold, you just can't push enough air into it no matter what.

If you are going to be doing 2500rpm or less all day, I am sure its a good compromise. The tiny inlet means it gets good midrange torque without boosting too early, which means the tiny turbo can still be small enough to spool instantly without going to the expense of multi-turbos. So for a 'normal' car that just gets driven everyday to work and back I am sure its a decent compromise.

But as soon as you start using them for competitive tuning, you hit limits pretty quickly.

Like I said, my buddy killed countless HDis trying to break...like..200hp or something unflattering like that. I don't remember what the exact numbers were but basically a Volkswagen TDI will do that all day long with some work, a 2.0HDi just can't take it. Cracks heads, throws rods, etc.

If only Volkswagen learned how to make nice cars hahahaha.

Chlorate
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Re: XUD tuning - XUD9 n/a cam in XUD7TE?

Post by Chlorate » 25 Nov 2014, 10:18

nametooshort wrote: Seems to be that HDis are less reliable than all the other commonrail families out there
Depends on which HDi you're thinking about, the older 2.0l 8v is notorious around these parts for being rediculously reliable - with good specimins pushing 300k miles before the car is finally consumed by the tin worm.

Anyway this is beside the point...

If I recall there isn't much difference between the bore of the 1.7 and 1.9 - in fact the heads may even be interchangeable....

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nametooshort
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Re: XUD tuning - XUD9 n/a cam in XUD7TE?

Post by nametooshort » 25 Nov 2014, 20:40

OK, well NOW I am confused.

I had a look through some parts listings and stuff, and it seems a lot of places list the SAME cam for ALL the 9s and 7s and DW8s, no matter turbo or not. The only variation is whether it's single or double slotted (for motors which have the other pulley).

It seems that all application data, from a early XUD7 n/a all the way to a DW8, points to one single shaft, the 0801E8.

For example this one of Ebay Germany

As you can see its clearly advertised covering the whole range.

So whats going on, im confused? Does anybody know the OE number of 'that' magical cam shaft that's the one to have?

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Re: XUD tuning - XUD9 n/a cam in XUD7TE?

Post by RichardW » 25 Nov 2014, 23:05

I don't think service.citroen lists the full gamut of shafts now, but it has

0801C2 for non turbo and 0801C9 for 1.7 turbo engines.

0801E8 does appear to be used on both NA and later turbo engines.

Haynes says

1.7 N/A Inlet 8 deg BTDC to 40 deg ABDC Exh 56 deg BBDC to 12 deg ATDC
1.7 TD inlet 4 deg 30' BTDC to 20 ABDC Exh 39 deg BBDC to 4 deg ATDC
1.9 N/A Inlet 4 deg BTDC to 35 deg BBDC exh 43 deg BBDC to TDC

Not quite sure how a valve can close AFTER TDC, but there you go....! 1.7 NA cam has a lot more opening than the turbo cam.

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nametooshort
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Re: XUD tuning - XUD9 n/a cam in XUD7TE?

Post by nametooshort » 25 Nov 2014, 23:51

So, looking at that, the 7 turbo has the lowest duration of them all by far, and actually the 7 n/a has the highest duration, even more so than the 9 n/a? So the 0801c2 is the grind to go for? However, it don't mention nothing about lift.

I wonder why 0801e8 is listed as the replacement for everything? maybe they made a one-size-fits-all replacement that superseded all the others?

Odd.

So the superior cam is the 7n/a? I might have one of those actually.

EDIT:
Ok now it's even more confusing. The 0801c2 is listed as being used in both 7 AND 9 n/a motors, (and also some volvos and benzes which kinda makes me wonder if there is a mistake someplace?)

However your spec list clearly shows different specs for 7 and 9 n/as. So they can't be the same for sure.

Maybe PugCit were just very messy with their numbers? Or there are mistakes in some database somewhere.

I wish there was a published list that just said cam number and specs.