J4R Head To Sequential Injection

[Flozman 4]

Hi All,

 

I was just wondering if it was as simple as drilling a cam phase sensor hole into the position as the RS head?

 

And are there any other little niggles ill have to overcome to make the ECU at home i know its an odd ball conversion but I have my reasons?

 

Any advice is welcome

[dcc 855]

assuming you mean the XU10J4R head, I think you'd need to run the J4RS cam's/pulleys for the sensor to read correctly.

 

Its quite a good head according to sandy, bigger valves, but narrower ports

 

The J4RS ecu is obviously mapped for the engine, with its timing etc - but I actually had a 306 gti shell with J4R engine on J4RS management, without the cam sensor. ran pretty well.

[welshpug 1,626]

it really is as simple as drilling out that casting, the RS and R use the same type of cam pulley, the hub is different.

 

there's also the coilpacks that would need some brackets making up as there's half the number of lugs on the R due to the single unit used rather than 4 separates.

[Flozman 4]

assuming you mean the XU10J4R head, I think you'd need to run the J4RS cam's/pulleys for the sensor to read correctly.

 

Its quite a good head according to sandy, bigger valves, but narrower ports

 

The J4RS ecu is obviously mapped for the engine, with its timing etc - but I actually had a 306 gti shell with J4R engine on J4RS management, without the cam sensor. ran pretty well.

 

Cheers Mate, i'm hoping to create a setup with a nice solid spread of torque rather than just peak horsepower. They are not bad lumps the J4R's but designed for towing rather than racing

 

it really is as simple as drilling out that casting, the RS and R use the same type of cam pulley, the hub is different.

 

there's also the coilpacks that would need some brackets making up as there's half the number of lugs on the R due to the single unit used rather than 4 separates.

 

Thanks Mate, useful advice as always.

[petert 554]

Here's one that's been done, not by me. It's a little rough, looks like it was done with a dremel, but would have worked ok. Don't dismiss the J4R as being tow unit. The valves and port sizes are identical to an Mi16. All that holds them back is the cams. If you use the universally accepted allowance of 0.007" between coils of valve springs at solid height, the maximum permissible cam lift is 0.380". More info here: http://www.taylor-en...6_camgrinds.htm

Edited March 1, 2012 by petert

[welshpug 1,626]

oohh, so RS cams in an R isn't really a good idea then!

 

can the RS springs be used if the RS stem seals are used?

[petert 554]

You'd have to change the entire lot over. I'm not sure if the RS seal fits on an R head. The R has an integrated seal/spring base.

[welshpug 1,626]

I shall have a look if I remember, got an XU7 head I can look at too.

[Anthony 1,000]

Different age J4R heads use different stem seals - some I believe can be changed to RS type, some can't.

 

(if nothing else, remember that there's two different stem dismeters used on J4R engines depending on age!)

[guffe 2]

Uh, this was news to me. Any chance I could escape using the RS cam with stock XU7JP4 springs etc.? Max revs would be round 7500

[welshpug 1,626]

same springs and valve stem seal as the 10J4R, so that'd be a no.

 

 

(IF all 10J4R and 7JP4 springs are the same coilbound height, there are two part numbers shared by both, August 30, 1998 is the changeover date, pics of the lower stem steal looks the same, incorporates the lower spring seat)

[guffe 2]

Drifting away from the original topic, but people here have used the 7JP4 head for high performance purposes and supposedly have used high lift cams. How have they solved this valve spring problem?

[welshpug 1,626]

yes, Sandy and Mark Shillaber have built a few race engines with them IIRC, he uses aftermarket valve springs and checks the installed heights etc.

[Sandy 189]

Don't think Mark has, but I've used both, but favour the XU7J4 head above all, it's cast so small that I can port it pretty much exactly how I want, rather than having to accept the shape of 10J4R and 10J4RS, because they are so big to start with. Recently had 197lbft from a 2 litre with XU7 head on 99RON fuel, personal best lbft/litre (calibrated/corrected engine dyno, not rollers!) The earliest 7 and 10 heads had 7mm stems apparently, but I've never seen any. Early 6mm stem have a guide with 8.8mm top that'll take a carefully fitted GTI6 stem seal, but most are 9.8mm top that will only take the top hat style seals. I cut the tops down to take GTI6 seals for convenience and to make room for double springs.

[Sandy 189]

Uh, this was news to me. Any chance I could escape using the RS cam with stock XU7JP4 springs etc.? Max revs would be round 7500

 

I ran GTI6 cams on the later tapered XU7J4 springs with no problems in my Goodwood years ago.

[guffe 2]

I ran GTI6 cams on the later tapered XU7J4 springs with no problems in my Goodwood years ago.

So there might be a minute chance to run with original 7JP4 springs and RS cams? I have later model head, so I suppose only way to be sure is to measure. Damn if I would known this when the head was disassembled...

[Sandy 189]

Yes, as always, measure to know for sure!

[guffe 2]

Yes, as always, measure to know for sure!

Yeah, but if I only had known... I think I was oblivious to this problem because the Catcams catalog says that OEM valve parts can cope up to 10.95mm of lift, but that surely that is only true with the RS engine (Catcams lists the Xantia 98kW also in http://www.catcams.be/800x600/prod01Alist.htm?PN49031xx.js)

 

Lesson #1: Always measure! And if you are sure, measure again!

[petert 554]

That all depends on what you think is a save distance to leave between each coil and at coil bind.

[welshpug 1,626]

surely coil bind is when they touch? so if they don't touch...

 

or is it not that simple?

[petert 554]

Maybe I didn't express that well enough.

 

eg If the spring is 1.000" high at solid, fully compressed, and there are five spaces between six active coils, allowing 0.007" clearance per coil, the safe compressed height is 1.035".

Edited March 6, 2012 by petert

[guffe 2]

Little browsing with servicebox and I found that EW10J4S uses the same retainer (0951 47) and stem seal (0956 45) with different spring (0952 A4). Only downside is that the springs are triple the price compared to J4R/JP4 springs

 

edit: If this is true http://www.catcams.be/datafiles/docs/springsetup49016xx1.htm then the EW10J4 spring (0952 90) would be perfect as is can handle more lift and third of the price! (okay, it has less spring pressure than the 0952 A4)

Edited March 6, 2012 by guffe

[Sandy 189]

10.9mm is based on the spraybar strike on the RS head I would say, 7 and 10R heads don't have spray bars, but springs are likely to limit lift anyway. I think I posted some spring data on these back along, god knows where though.

[petert 554]

Here's some research I did:

 

http://forum.205gtidrivers.com/index.php?showtopic=118620

 

I don't see an issue however, as 0.380" is heaps of lift. My Stage I Mi16 profile has 0.350" of lift. It's easy to put that grind on to J4R cams.

[Flozman 4]

Here's some research I did:

 

http://forum.205gtid...howtopic=118620

 

I don't see an issue however, as 0.380" is heaps of lift. My Stage I Mi16 profile has 0.350" of lift. It's easy to put that grind on to J4R cams.

 

 

Thanks for that Peter, if I go to a machine shop is that the only thing ill need to tell them?