Xu10j2 Head

[wardy18 33 1 Cars]

Hi all,

 

I have a XU10J2 head kicking around from a 306 2.0ltr XSi i dumped, im tempted to have a little work done to this and throw it on the 1.9 XU9 bottom end.

 

Obviouslyh the biggest downfall of this head is the smaller exhaust ports, can these be easily ported to make a good little upgrade?!

 

What else needs to be done to the head to make it fit straight on?!?

 

Will my Catcam and double valve springs from my XU9J2 head fit straight in???

 

Regards

 

Simon

[TVH 0]

Hi all,

 

I have a XU10J2 head kicking around from a 306 2.0ltr XSi i dumped, im tempted to have a little work done to this and throw it on the 1.9 XU9 bottom end.

 

Obviouslyh the biggest downfall of this head is the smaller exhaust ports, can these be easily ported to make a good little upgrade?!

 

What else needs to be done to the head to make it fit straight on?!?

 

Will my Catcam and double valve springs from my XU9J2 head fit straight in???

 

Regards

 

Simon

 

As a rule of thumb, exhaust flow should be 80% of intake flow. According to the flow graphs posted on the forum, 3 angle seats will do the job. just get nough valve lift to overcome valve shrouding issues. Xu9j2 valve springs are shorter than xu9ja, xu9jaz xu5ja and xu10j2 springs.

[wardy18 33 1 Cars]

what is the xu9ja head from?

 

really.....3 angle valve seats is enough?!?

 

oh and sorry what u mean by valve shrouding issues?

[pug_ham 244 3 Cars]

Zip file of XU10 flow graphs.

 

Graham.

[wardy18 33 1 Cars]

wow thats impressive for a practically standard head compared to a BV XU9 which costs a good 800quid to do!!

 

so is there no way i can use the double valve springs from the XU9 head into the XU10?!

[sub205 5]

wow thats impressive for a practically standard head compared to a BV XU9 which costs a good 800quid to do!!

 

so is there no way i can use the double valve springs from the XU9 head into the XU10?!

cam/valve springs can be used and are interchangeable. the only differences between xu9 and xu10 heads are the inlet ports, bigger inlet valves (exhaust valves should be the same size! not smaller!) and the double-rilled valve-locks. (the 2 small parts in the head of the valve / spring assembly.

 

another thing to mention: the xu10-cams are locked at the 4th bearing, the xu9-cams are sometimes locked with a small piece of metal mounted to the first bearing. but i think your cam should have both variants, as nearly every aftermarket cam does ...

Edited July 14, 2009 by sub205

[wardy18 33 1 Cars]

excellent, so pretty much i get this head pulled apart and rebuilt with my Double Valve Springs and Catcam from my XU9 head one i have had the 3 Angle Valve Seats and a Head Skim done and i should be ready to go!!

 

Couple more little things, not having looked too much at the head yet do you use a XU9 Cam Cover as the XU10 had a massive plastic contraption on it, also does the XU9 Dizzy and Water Housing fit straight on from the XU9!?

 

Cheers guys, id have done this a long time ago if i knew it didnt a great amount of work costing hundreds, i was always told "Exhaust throats too small so no point" but if all you need is 3 Angle Valve Seats then happy days, obviously could always do slight smooting/polishing of the throats etc

[Anthony 1,003]

Couple more little things, not having looked too much at the head yet do you use a XU9 Cam Cover as the XU10 had a massive plastic contraption on it, also does the XU9 Dizzy and Water Housing fit straight on from the XU9!?

Yes, use the XU9 cam cover - you'll need the cam bearing cap nuts from the XU9 too. XU9 thermostat housing bolts straight on, as does the dizzy (assuming you're using an XU9 thermostat housing - XU10 one is designed for a wasted-spark coilpack)

 

Remember that you need to skim alot off the head to bring the compression upto that of an XU9, as the chamber is bigger on an XU10.

 

I'm running a fettled XU10 head on an XU9 bottom end, and it works well.

[wardy18 33 1 Cars]

yeh thats what i wanna do, i was always told the head height on XU9 and XU10 were the same, see attachement

 

i can use the attached to work out what has been taken off already in previous skims and what i am left to take off to get to a 60thou total skim

 

great news that everything swaps straight over, thanx alot for the advice

Edited July 14, 2009 by wardy18

[wardy18 33 1 Cars]

what have u done to your XU10 head and do you know what sort of power BHP/Torque you have gained!?

[sub205 5]

another thing to mention is that the size of the chamber ist not optimal!

you have aprox. 1.5mm space at some points, because the xu10-piston is 86mm (83mm xu9), this is obviously suboptimal!

 

you get a corner which will disturb the gasflow, possibly a weak spot on this conversion.

[Anthony 1,003]

what have u done to your XU10 head and do you know what sort of power BHP/Torque you have gained!?

The head was done by Mattsav at QEP. It was skimmed for approximately 10.2:1 compression, 3 angle valve seats, flowed/tidied valve throats, and the port shape matched to the XU9 manifold. It's running a mild Kent PT36 cam and vernier, and is otherwise standard.

 

No idea on power and torque I'm afraid as I've not rolling roaded it - it feels good and is noticeably quicker than other fresh 1.9 8v's that I've driven, so that's good enough for me. Others that have driven the car agree that it feels quick for an 8v.

[wardy18 33 1 Cars]

another thing to mention is that the size of the chamber ist not optimal!

you have aprox. 1.5mm space at some points, because the xu10-piston is 86mm (83mm xu9), this is obviously suboptimal!

 

you get a corner which will disturb the gasflow, possibly a weak spot on this conversion.

 

i assume there is no way to overcome this other than taking engine out and gettin the inside top of the liners flared out slightly!?

[wardy18 33 1 Cars]

ok i have spoken with Matt at QEP and the new head along with my catcam and double valve sprint from the XU9 and my carbs inlet mani will be sent to him straight after my 1st Aug Hillclimb to then get the cam fitted, 3 Angled Valve Seats, Port Matching, head skimming, valve springs fitting, cam fitting and shimming and anything else he can do

 

he gave a quick estimate and doesnt seem too too expensive

 

cant wait to get it back and get it fitted to see what power gains i can get

[Jakob 1]

another thing to mention is that the size of the chamber ist not optimal!

you have aprox. 1.5mm space at some points, because the xu10-piston is 86mm (83mm xu9), this is obviously suboptimal!

 

you get a corner which will disturb the gasflow, possibly a weak spot on this conversion.

 

So true!

Sadly the flow measurement did not tell on what diameter it was measured on 86mm vs. 83mm. Most likely all on 86mm. You will need to measure the XU10 head on a 83mm setup otherwise it tells you nothing about the flow potential on a xu9 engine.

Many owners of XU10 head conversions on XU9 block end up with questions like why they see less power than others with ported XU9 heads. Why...valve shrouding!

 

What are the flow cfm?? they are not listed on the graphs???

[wardy18 33 1 Cars]

I'm not expecting the same power as a sorted xu9 head as obviously I'm not pumping in 800 to 900 quid into a head!

 

Again what is valve shrouding?

[DrSarty 90 1 Cars]

Again what is valve shrouding?

 

I'll attempt to explain using my non-technical background, using what QEP explained to me on my engine. There is no reason why the same principles won't apply.

 

My XU10 block was bored out from 86 to 87mm. The Mi head I used has 'pockets' (naturally) where the combustion chamber is. This pocket/chamber has a bore to match the block.

 

In my case - and I gather in yours too - this pocket is not as wide as the cylinder block bore and therefore there is metal around the edges of the valves which could/will restrict fuel and air entry into the engine. In effect the valves will be choked a little.

 

Opening up the combustion chamber bore to match the block bore removes this restriction and allows the fuel/air mixture to enter and distribute better into the combustion chamber giving you better performance.

 

If the removal of this restriction is not possible your valves will remain restricted/'shrouded' which is undesirable.

 

HTH

[Jakob 1]

I'm not expecting the same power as a sorted xu9 head as obviously I'm not pumping in 800 to 900 quid into a head!

 

Again what is valve shrouding?

 

Clearance around the valve. There is huge difference when you put a 43mm inlet valve free floating in a 86mm bore block or park it at the wall side of a 83mm block.

Look at the flow measurement. The gain starts at lift of 10mm to 15mm on the valve.

Take your XU9 block of 83mm and place your XU10J2 2 valve 86mm head on top. Set the inlet valve (43mm) to lift between 10-15mm. The valve go into your block. Now look/measure how much space you have at your inlet valve in the 83mm block near the wall. There are lots of theory about valve clearance / shrouding.

[All Praise The GTI 3]

sorry for the hijack. jakob ive tried reply your pm but your inbox is full mate

[Saveit 0]

Well ill have my XU10 conversion on rolling road very soon. Its got twin webers and PT27 cam and some other fiddly things done to it. Hope to see 150 bhp.

[Jakob 1]

Well ill have my XU10 conversion on rolling road very soon. Its got twin webers and PT27 cam and some other fiddly things done to it. Hope to see 150 bhp.

 

Sorry, but 150bhp would IMO be a very poor result!

Ported XU9 head, pt36 cam, standard induction, kn-filter. Nothing else will net you 155 bhp and 150hp with cat. I had that for several years. The pt36 is just as bad/good as the standard OEM GTI cam.

 

If you add to that webers or throttle bodies and not to mention the pt27 cam you will have much higher flow !!!

[wardy18 33 1 Cars]

ive been told on the standard XU9 head with 3 angle seat, catcam, twin 45 webbers and a 10.9CR i should be running about 165bhp!!

 

with regards to the valve shrouding, Dr Sarty, i am the opposite way round, im putting a XU10 head on a XU9 block, so i have a combustion chamber in the head of 86mm bore ontop of a liner bore of 83mm!!

 

This is why i ask if the top of the liners could be machined ever so slightly to removed the top inside edge of the liner and so flaring them out from 83mm to 86mm to match the head, just to improve the flow in the combustion chamber????????????????

[DrSarty 90 1 Cars]

with regards to the valve shrouding, Dr Sarty, i am the opposite way round, im putting a XU10 head on a XU9 block, so i have a combustion chamber in the head of 86mm bore ontop of a liner bore of 83mm!!

 

I gathered that from the posts that followed, although the principle's the same. You are shrouding the valves either way.

 

Really don't know about your last question, as that's suggesting taking 1.5mm of the inside lip of the liners.

 

Somebody said earlier that this works quite well, and now it seems to be getting very complicated. I'm intrigued.

[Saveit 0]

Sorry, but 150bhp would IMO be a very poor result!

Ported XU9 head, pt36 cam, standard induction, kn-filter. Nothing else will net you 155 bhp and 150hp with cat. I had that for several years. The pt36 is just as bad/good as the standard OEM GTI cam.

 

If you add to that webers or throttle bodies and not to mention the pt27 cam you will have much higher flow !!!

 

Well then ill be upping my expectations

[Jakob 1]

Well then ill be upping my expectations

 

I refered to XU9 top on XU9 block.

As mentioned some people get disapointed with the XU10J2 head on the 83mm block.

Anyway more lift help equal flow loss by valve shrouding so your pt27 will help.

Good luck with the tuning/rolling - remember to post your result here. That will be quite interesting