Xu10 J4rs Versus Xu10 J4r

[BackStreetRacecars 3]

I have found an xu10j4r head and loom today at one of my local breakers yards.. . I was wondering what the difference is between this and the one found in the gti6 or xsara vts i think? Anyway.... is the loom the same? I wanted to try and get the loom and the head then get gti6 inlet and exhaust manifolds.... Jus wanted a quick concise difference between the R and the RS head and loom....I also wanted to know if the timing belt cover will work with an aluminium mi bottom end.... cheers!!!

Edited March 17, 2009 by BackStreetRacecars

[24seven 104]

not sure about the loom, but the R and RS heads are similar, but the RS has bigger ports, double valve springs, sodium filled valves with smaller diameter stems and a more aggressive cam. the '6 manifolds will bolt straight on, and I've been told that for outright tuning potential the R and XU7 heads are preferred, as they have more metal on them to work with when shaping the ports.

[petert 554]

but the RS has bigger ports, double valve springs, sodium filled valves with smaller diameter stems

 

Both the R and RS heads have 6mm stems. In terms of port and valve sizes, the R is basically identical to an Mi16 head.

Edited March 18, 2009 by petert

[BackStreetRacecars 3]

so I'd probably be better waiting to find a Gti6 head.... The money that the breakers want for it is too much just to buy it anyway... They'd probably want the same for the RS anyway... What other models bar the Gti6 and the xsara vts have the xu10j4rs head?

[DrSarty 90 1 Cars]

so I'd probably be better waiting to find a Gti6 head.... The money that the breakers want for it is too much just to buy it anyway... They'd probably want the same for the RS anyway... What other models bar the Gti6 and the xsara vts have the xu10j4rs head?

 

I thought collectively the answers above were saying you may as well start with the J4R head? Did I miss something? More work, but cheaper starting price and more potential.

[BackStreetRacecars 3]

thats the thing though...... potential.... I cant afford to buy a head and then spend hundreds of pounds on it to get to somewhere that the gti6 head is already at. Not that I'm saying that the gti6 head is better than a ported,polished etc R or Mi head I'm not, but for the amount of bang per buck the 6 head delivers better.... If you know what I mean.... . I shall have to do alot of thinking.... And cover post it notes with ideas and run through them all!!!

[BuD 0]

As far as the loom is concerned they arent the same between j4r and j4rs as the coilpacks are individual on RS and one single unit on R. Dont know if there are other differences.

[welshpug 1,627]

the thing is, being essentially identical in port size to the Mi16 means it'll flow enough for 250 bhp+ if your cams and bottom end are capable of it....

 

as standard yes the gti6 maybe the best place to start, but once you start modifying the differences don't seem to matter one bit.

[BackStreetRacecars 3]

the thing is, being essentially identical in port size to the Mi16 means it'll flow enough for 250 bhp+ if your cams and bottom end are capable of it....

 

as standard yes the gti6 maybe the best place to start, but once you start modifying the differences don't seem to matter one bit.

 

 

Well if it made anything like that I'd be happy!! I think I'll maybe phone back about the J4R head as I cant see a gti6 one appearing roung here too soon. And I want to start building this engine!! Does anyone have the flow figures for these heads? I remember seeing a post ages ago with someflow figures for different 16v heads......

[DrSarty 90 1 Cars]

You might do well PMing (and chatting with) Pip470, who ported out his XU7JP4 head by hand (and Dremmel). The work isn't that tough.

[24seven 104]

Both the R and RS heads have 6mm stems. In terms of port and valve sizes, the R is basically identical to an Mi16 head.

 

 

ahh, gotcha. On that basis it should be fairly straightforward to extract Mi16/S16 performance from the J4R then?

[welshpug 1,627]

the theory certainly suggests it, also most XU7JP4's have the same valves as the 10J4R, just smaller ports.

 

I have a question that's along similar lines, I have seen that a regrind of the original RS cam is quite limited if you stay hydraulic due to the decreasing base circle, but what if say an XU7JP4 or 10J4R cam would be reground, are they a better starting point?

Edited March 20, 2009 by welshpug

[BackStreetRacecars 3]

getting a bit confused now.... maybe i've just been doing too much uni work but.... what is the head from the iron block mi like(taking it that its the same as the alloy block one?) in comparison to the xu10 j4r head? the 8 exhaust ports and? How does an Mi head flow compared to an R head?the afore mentioned J4R head flowing enought for 250bhp what is the Mi one good enough for in standard guise? This is getting more and more interesting.... probably been covered a trillion times.....oops.

[welshpug 1,627]

Only the Mi16 had the 8 exhaust ports, and yes, bar some minor details on fixings and the like they are the same for 1.9, 2.0 and 2.0 T16.

 

The J4R architecture is nearly the same as the RS, just slightly different finishing to the ports and different vavle sizes, as PeterT said, they flow near on the same as the Mi.

[Mandic 0]

but the RS has bigger ports, double valve springs, sodium filled valves with smaller diameter stems and a more aggressive cam.

 

[24seven 104]

 

 

http://www.autoeducation.com/rm_preview/valve_train.htm

 

scroll to the bottom

[kutija 1 1 Cars]

He knows what are sodium filled valves but are you sure that they are on the 10j4rs?

AFAIK there are only sodium filled valves on T16 head.....don't see the point of them in NA car....

[DrSarty 90 1 Cars]

He knows what are sodium filled valves but are you sure that they are on the 10j4rs?

AFAIK there are only sodium filled valves on T16 head.....don't see the point of them in NA car....

 

Purely for interest: my RWD 600BHP E36 project, which is using a Saab 9000 2.3 turbo engine as a base, is using the Trionic 5 head rather than the newer 7. This is based on advice from Saab tuning experts, who say the T7 head which has the lighter, sodium filled valves in practise had weaker valves which were prone to breakages.

 

Back on topic.

[Mandic 0]

AFAIK exhaust valves are two piece. A 21/4N or 21/2N SS head and lower stem friction and EN52B on upper stem. One can use a magnet to determine the crosspoint. And T16 is the only one in Pug range having sodium filled valves.

 

Cheers

 

Ziga

Edited March 21, 2009 by Mandic

[kutija 1 1 Cars]

Purely for interest: my RWD 600BHP E36 project, which is using a Saab 9000 2.3 turbo engine as a base, is using the Trionic 5 head rather than the newer 7. This is based on advice from Saab tuning experts, who say the T7 head which has the lighter, sodium filled valves in practise had weaker valves which were prone to breakages.

 

Back on topic.

 

Hmm you too are putting saab engine into the bmw

There is a guy in Serbia that finished his600 hp project but in E30 M3...

 

here's the link

 

http://www.cbc.rs/forum/viewtopic.php?f=15...&start=2075

 

He also has 206s16 and had throtlle bodies at first but now is doing ITB+turbo on the 206s16

[24seven 104]

I was always under the impression that the RS head had sodium filled valves. pretty sure I read that on here somewhere.

[BackStreetRacecars 3]

so...... another chapter the thread..... is the Mi head related to the oil control problems? I read on Camerons gti6/mi hybrid thread that the gti6 head kinda sorts out the oil surge problems? maybe I read it wrong!!! anyone??

[DrSarty 90 1 Cars]

so...... another chapter the thread..... is the Mi head related to the oil control problems? I read on Camerons gti6/mi hybrid thread that the gti6 head kinda sorts out the oil surge problems? maybe I read it wrong!!! anyone??

 

My understanding is that the Mi head requires a fair amount of oil in its basic function. IIRC it holds 1.5 to 2L (but ready to stand corrected), and does literally that, 'holds' the oil.

 

As a result, particularly on track work or ludicrous road hooning with long sweeping bends, there is potential that insufficient oil can return to the sump, meaning the oil pick up becomes starved and the oil starvation issue causes crank lubrication problems/failures.

 

I wouldn't say the head is the source of the problem; rather an oil supply problem, as it's proven that more oil left available by baffling the sump, adding a spacer, an extended pick-up and a windage tray or all of the above often cures the issue. Others go further and tap the head with an oil return or go the whole hog and dry sump it.

 

From what I've read though, the GTI6 (RS) and J4R heads IN CONJUNCTION with the other goodies the XU10 bottom end provides - which is most of what's listed above - means the problem isn't so great.

 

How's that for a bluff?

Edited March 22, 2009 by DrSarty

[BackStreetRacecars 3]

is this a trust me I'm a doctor moment?!

 

I know this is all stuff I should be experimenting with and findng out myself... but it seems a shame to waste the wealth of knowledge that is this forum!!! Was trying to search for a thread for running different management options on the Mi head, if i do go that route I wanted to go '6 management or similar anyway.... as it has knock sensors and lambda so i'd be less likely to blow it up with higher comp ratios etc.... so if anyone can remember any similar ones? obviously most throttle bodied Mi's will have a similar set up to what I'm going for..... off searching I go again!!!

[BackStreetRacecars 3]

is this a trust me I'm a doctor moment?!

 

I know this is all stuff I should be experimenting with and findng out myself... but it seems a shame to waste the wealth of knowledge that is this forum!!! Was trying to search for a thread for running different management options on the Mi head, if i do go that route I wanted to go '6 management or similar anyway.... as it has knock sensors and lambda so i'd be less likely to blow it up with higher comp ratios etc.... so if anyone can remember any similar ones? obviously most throttle bodied Mi's will have a similar set up to what I'm going for..... off searching I go again!!!

 

 

 

Anyone? The management I have found is in a 2.0 16v 406 coupe, I possibly have the rest...... Is it worth getting all the sensors, loom and ecu? Will it be worthwhile doing that instead of running afm dizzy etc?/ I know it will run nicer but what about power gains? Would it be worthwhile getting the loom etc then gettin a gti ecu? any suggestions?