The Racetractor. The End.

[bashbarnard]

Is it safe to open pre cups up? I thought they were a specific size to help ignition? I could be wrong though

[Piggy]

They are indeed. So extreme caution needs to be applied.
I am doing research on it. Will report.

[bashbarnard]

Awesome would love to know more

[Piggy]

Me too!!

[Paul_13]

I had new pre cups pressed into into my head
3 were vastly bigger than the other so I opened up the other one

[Piggy]

Only info I can find so far is the precups are VERY hard metal and should be removed for head skimming otherwise the skim is likely to dislodge the cups

[eskimogod]

So after getting the head skimmed they will they stick out the head a bit..?
Or get them machined separately

Thoughts about geting them ceramic coated? Or some other heat treatment to prevent the cracks

[Paul_13]

Mine are ceramic coated

[Piggy]

Mine are ceramic coated

Oh really!? Tell me moar!!

---

No they wont stick out but info seems to say it can dislodge them which then you dont know till later.

I fail to see still how a lose one can 'drop' as a big chunk of it is pressed against the block when the head goes on

[Ruan]

I did a crap load of research into precup related shenanigans back along...

The result I came out with is - go direct injection or leave them the f*ck alone! I've seen people ceramic coat them to keep the heat out, however this generally causes problems, most I've seen - the coating flakes off - no matter what you do, the precup is DESIGNED to run intensely hot, when running, this provides better, more instantaneous ignition, especially when the coolant temperature is down and during cruising, improves economy and combustion quality - this is one of the main ways the IDI engine is infact better than Direct Injection. High power levels accelerate the cracking, but you take apart any stock 90hp XUD9 and the precups will be cracked... I've only ever see ONE drop a cup.

Also if the precup is cooler, you get more noise - half the reason IDI engines were invented in the first place was for NVH reasons, the precup being hot is for the same reasons that most DI and late XUDs have twin-stage injectors and now on Commonrail, multi-burst injection - all to reduce noise...

I personally don't think unless you went down the road of different design injectors with more up-to-date precups (read Kubota...) you'd see any benefits... End of the day, going from 9 > 11mm is the only difference in the actual injection rate per crank degree/mS, when you crank the max fuel, you're doing nothing but increase the duration - hence IMHO there's little need to have larger precups... You're shoving the burning fuel mix through the hole at the same rate no matter whether it's idling or making 200hp - it just takes longer to do so.

The Merc OM603 and OM606 is an Indirect motor, no adjustments to the precups (admittedly of a different design..) and they're making happily up to 600hp with reasonable reliability... Just the slight issue of blowtorching pistons instead.

[Piggy]

Of more concern is that skewiff precup.

Dont need this agro right now. Need this head to be good

[Piggy]

Guna need to sort that precup.

Hmph.

However i have found a engineering place with all the right kit only 10min from me...only they have experience limited to classic porsche and VW petrol. Hoping they can still help!

[procta]

Guna need to sort that precup.

Hmph.

However i have found a engineering place with all the right kit only 10min from me...only they have experience limited to classic porsche and VW petrol. Hoping they can still help!

if they have experience in that sort for stuff, then sure to Christ they should help you out.

[C2K]

Only info I can find so far is the precups are VERY hard metal and should be removed for head skimming otherwise the skim is likely to dislodge the cups

most I've seen - the coating flakes off - no matter what you do, the precup is DESIGNED to run intensely hot, when running,

Very hard, and very hot... Suspect this will be Inconel 600? in which case i'm not surprised coatings fall off tbh.

[Ruan]

Yeah, it's Inconel 600

[welshpug]

I've had one fall off, only because my brother was a muppet and kept driving with a properly fooked rad and HG.


My advice would be to find a proper diesel specialist, not just any engineering place, most wont know engines especially diesel.

[Piggy]

Point me to one then welshy...theres none round here!

[Seb_Ryan]

Theres a diesel specialist in cardiff, over an hour run each way.. Cant remember name though lol

[Piggy]

Theres a diesel specialist in cardiff, over an hour run each way.. Cant remember name though lol

4hour round trip for me...
And I would have to do it twice!!

[welshpug]

possibly http://www.southwalespistons.com/ how big is the Cotswolds? I can make it to Gloucester in less than an hour!

there's a head specialist up the valleys from me too http://www.jse-services.co.uk/page1.html

this would be a good place to look for more local specialists

http://www.federationofengineremanufacturers.co.uk/

[Piggy]

And i am about 45min from gloucester!!

[Piggy]

Right...
After some emailing and calling...at 4pm I headed off for Bromsgrove!

MJA engineering for the win! They replied within 5min of me emailing, I sent them some pics, they gave me a quote and said it be no issue and wouldnt need it for more than a day!

Martin there is a top bloke and showed me around the workshop which is like heaven for me and showed me a couple rallycross and stock car V8 buggies too! Oh and their latest install of a 700bhp engine dyno!

Will have pics and video when I collect

Although...once fuel, buying the head from spike and this bill is taken into consideration I think I could have bought a recon head for the same amount

[Paul_13]

You going to recon your injectors?

Just had mine and fook me it's made a difference

[Piggy]

Recon 10k miles ago

[spike2002]

Should of said dude I know martin jayne and andrew at mja very well family friend

[Piggy]

I couldnt have posted much more about it!!!

Ring em and get em to make a cash payment discount then!!

[bashbarnard]

Any news about precup mods then man??

[Piggy]

[bashbarnard]

So something then but obviously not saying. Hope you dont keep it a secret love to know

[Piggy]

grinding tomorrow!