Xu9 & Xu10 Head Cc

[wardy18 33 1 Cars]

Hi all,

 

I have searched and searched but cant find the answers

 

Im sure someone will know off the top of their head, can anyone give me the folowwing:

 

XU10J2 Head CC

 

XU9J2 Head CC

 

XU9J2 Piston Dish CC

 

Thanx

 

Simon

[wardy18 33 1 Cars]

Hi all,

 

I have searched and searched but cant find the answers

 

Im sure someone will know off the top of their head, can anyone give me the folowwing:

 

XU10J2 Head CC 36cc

 

XU9J2 Head CC 32cc

 

XU9J2 Piston Dish CC 15cc

 

Thanx

 

Simon

 

After hours of searching i may have found the answers, BUT PLEASE CONFIRM

[welshpug 1,655]

could try searching for XU9JA as that's the more common derivative.

 

not sure which the 9J2 is?

[wardy18 33 1 Cars]

Any ideas what dish cc the 1.6 gti B6D pistons have?!

[James_R 3]

I had the XU9J2 (GTi head) chamber at 36cc's

[wardy18 33 1 Cars]

The std CR is 9.6, with a head cc of 32 a CR of 9.9 is achieved

 

If it were 36cc then the Std CR would be 9.28 which seems low.

 

This is going on a Compressed Gasket of 1.2mm and -15cc Piston Dish!!

 

 

 

Anyone know the 1.6 Gti (B6D) Piston Dish cc!?

[wardy18 33 1 Cars]

ok i think 1.6 B6d Pistons are also 9cc Dish

 

...........and think ive found a solution!!

 

A set of Mi16 Pistons, 0.38mm Shorter giving an extra 2cc BUT the piston Dish only being 2.8cc so this gives a total of 4.8cc.

 

With a Std Head Gasket Compressed at 1.2mm and a head CC of 32cc on a XU9 block this should give a good Race Engine CR of 11.03:1

Edited August 21, 2009 by wardy18

[DrSarty 90 1 Cars]

You're clearly working hard at this Si. Do you need to consider that the Mi pistons will have valve pockets (x4)?

 

And if you can use them, just make sure you get XU9 Mi pistons and not XU10 ones (83mm v 86mm bore) .

 

I would be amazed if no-one's tried this before though.

[wardy18 33 1 Cars]

You're clearly working hard at this Si. Do you need to consider that the Mi pistons will have valve pockets (x4)?

 

And if you can use them, just make sure you get XU9 Mi pistons and not XU10 ones (83mm v 86mm bore) .

 

I would be amazed if no-one's tried this before though.

 

 

Mate im rushed, ill have the new XU10 head next week and its gotta be fitted and running by 31st but i cant run std XU9 pistons as the CR will be about 9.2:1, with DFZ or B6D pistons i can get 10.2 or with D6C Mi16 pistons i can get 11.0 which is perfect!!

 

oh and i cant skim the head for reasons ill reveal soon

[DamirGTI 342]

.... could use 405 1.9 SRi pistons as well if you wish more than 11.1 CR mark as they're fully flat top type - no valve cut outs , no dish

 

Damir

[wardy18 33 1 Cars]

.... could use 405 1.9 SRi pistons as well if you wish more than 11.1 CR mark as they're fully flat top type - no valve cut outs , no dish

 

Damir

 

 

Well ive found a good set of Mi16 ones but i just need to ensure they 1.9 and not 2.0ltr, they are stated as 83mm so 99% sure they 1.9

[welshpug 1,655]

don't forget you'll need 1.9 Mi16 rods as well, unless you're getting the pistons or 8v rods machined to suit.

 

 

what's wrong with the old engine?

[wardy18 33 1 Cars]

Yeh these are a full set rods and pistons I'm looking at!

 

she's just lacking a bit of power within the class and I've gained the XU10 for nothing and a XUD9 block for peanuts so I'm goin to utilise them and build a powerful engine which the car now deserves!

 

Ill get the plans up soon, I don't wanna start yet another engine thread that never happens so need to be sure of what I'm doin before hand this time!

[DrSarty 90 1 Cars]

Ill get the plans up soon, I don't wanna start yet another engine thread that never happens so need to be sure of what I'm doin before hand this time!

 

Well said.

 

But as Damir says, surely you would do better with 83mm pistons designed for an 8v engine. You'll also up the CR. Can't be that hard to find.

 

P.S. 83mm Mi pistons will be the XU9 ones; that's why I said it. 86mm Mi pistons are for the XU10 iron block displacing 1998cc as opposed to the narrower bore, but longer throw of the XU9 at 1905cc.

[wardy18 33 1 Cars]

Well said

 

i knew you would appreciate that mate

 

 

But as Damir says, surely you would do better with 83mm pistons designed for an 8v engine. You'll also up the CR. Can't be that hard to find.

 

Is this because the Dish in the 8v pistons helps with combustion and so being that the Mi16 are flat top with slight recess for the 4 valves they not as effective?!

 

My only trouble is i need the engine back together by the 31st Aug (a week monday) Mi16 pistons are available now but DFZ pistons are going to be harder to find and wont give me as much CR.

[James_R 3]

Why not just get a complete XU7J4 pull the head off and then plonk your yeah on, flat top pistons over square, bang on compression and it will rev to 8.5k std, baffled sump, and you're in the sub 1800 class then. nice combo!! oh and will cost sub £100

[wardy18 33 1 Cars]

Why not just get a complete XU7J4 pull the head off and then plonk your yeah on, flat top pistons over square, bang on compression and it will rev to 8.5k std, baffled sump, and you're in the sub 1800 class then. nice combo!! oh and will cost sub £100

 

 

Nice idea but that block was never fitted to a 205 as standard (to meet class regs) im sure!??

[welshpug 1,655]

just stick it all inside an 8 valve block then.

[wardy18 33 1 Cars]

I dont know what to say, yes this would be great but i have a week to find the block, ship it to me, pull the old one out, swap everything across, fit the head and time up, fit engine in ready to go!!

 

Like i have said i will be having a new XUD9 block built so the XU9 with Mi16 pistons only has to get me through say 4 more events, i think the extra effort and money of the above XU7J4 fix out weighs its usefulness to me whereas the Mi16 Piston/Rod combo is a quick and cheap fix to get me through the rest of the season.

 

Thanx for the ideas and advice thou, its best to explore all options

[DamirGTI 342]

Problem with the valve cut out type piston crown is that the sharp edges around the cut outs might cause pre-ignition , so id smooth them up a bit , but not so much as they reduce the CR anyway .. but i dunno which and what kind of effect will this type of piston crown and XU10 8v combustion chamber shape made in terms of squish i.e. combustion efficiency ?! I would really like to see piston crown coloration after a few miles of running inside this engine !

 

Anyway , try it out and see how it goes even if you wont be satisfied you can always remove them out and fit a different set , like 1.9 DFZ or 1.9 SRi items ..

 

Damir

[James_R 3]

It's an alloy block, how anal are they?? they look the same, and they can't hardly see the block under the carbs and pipe work etc... the only thing you have to do it make sure the std GTi head/engine mount was retained as the XU7 one is a bit of a give away, but how knowledgable are the scrut's?? I know it's not in the true spirit, but it's hardly giving you a large advantage is it??

 

And I'm currently running this engine combo at the moment, it's a nice little revv'er

[wardy18 33 1 Cars]

Yeh old be great but I'm not goin against the msa rules! Plus I can't just find a block and drive a few hours to get it like most of you guys can, I have to get it couriered over which costs in excess off £100 and would take a week!

 

Its just not an option in my current situation but thanx for putting the suggestion forward!

[welshpug 1,655]

how about leaving your current engine in there and concentrating all your efforts on next years mega engine? you'd be able to afford proper management if you did that!

[James_R 3]

so the engine's not even failed?? I fail to see what the situation is now :s had assumed the original was dead :s

 

Didn't you win the last climb??

[wardy18 33 1 Cars]

sorry am I doing something wrong by wanting more from an engine? It really does feel like it!

 

I had an XU10 head so sent it to qep with my cam, costs 280 for the work and will give me better power, was intending to keep this on the xu9 block but then an XUD9 block came along and I now have the chance to do a project that I always wanted to do so the work was carried out on XU10 head as planned with minor adjustments to the original outcome ie not skimming the head so it suits the XUD9 block! However this means that I will left have a good head on a std xu9 block with bad cr for the short remainder of the season, along comes mi16 pistons as a short term fix! Over the winter the new XUD9 block will be built to go with the XU10 head built to suit and hey presto I have a killer engine for next year! Staying 8v has made this achievable within my budget, my availability and my regulations!

 

Finally a build that makes sense to me, I just need to persuade you all!

 

I have wiped up in season this year but only cause my main competition a 420bhp evo m3 has had problems BUT they are fixed now with only 2 local hillclimbs to go! I need to pick my game up for next year to match this and this engine will do it!