8v Block Options - More Cc Help Please

[mattbenselin 0]

I need to swap my DKZ block due to reduced compression and a piston problem. Was going to go for a D6B but have now thought about iron block.

 

This is due to their increased strength and options to raise CC. I'm thinking 2.0 8v iron block 86mm x 86mm, with a GTI head should give 11:1.

 

My head I want to use has been skimmed 40thou so this would bring CR up to 11:9, surely too high for a road car. Can I use thicker head gasket, which one?

 

I also want to swap the crank for my 88mm one which would bring CC upto 2044??? How would this effect CR and what's the best combination for CC and CR (its running a 285 cam).

 

 

What about using a diesel block such as the 2.1 iron with a 92mm crank. How would this effect the numbers on a GTI head with a 40thou skim?

 

Any thoughts, I like the sound of more CC and torque.

 

I have searched and read a load but really want more specific answers, help please !?

 

Matt

[Saveit 0]

Hi Matt,

 

Dont know how the Diesel block will affect the CR.

 

But regard to your question about headgasket, then just use a two headgaskets and tighten them by 30nm, 55nm, loosen all slightly, tighten again by 55nm, 80nm and 100nm. After having the engine started and getting up to normal running temperature re-tighten again by 110nm. Two headgaskets will solve your problem, cause yes, 11.9:1 is too high for a road engine.

[welshpug 1,629]

I don't think 11.9 is too high, just make sure its mapped properly.

[Tom Fenton 1,529]

Please do not use 2 head gaskets, this is not a good idea.

[DamirGTI 331]

In between the two ideas , id stick with light weight ally block ... build great deal of squish and CR and you'll have LOADS of torque all around the rev range = cheap , easy and effective

 

Damir

[mattbenselin 0]

Because I have a DKZ block now which gives lower CR (with my head about 10:1 (40thou skim)) and the fact that the numptie who built it before I got it put the pistons in the wrong way round I need to either swap the pistons for some D6B (giving 10.4:1CR) or just swap the block for something else. Easiest thing just to swap the block which I why I started thinking about my options.

 

I like the sound of 2litres+, it will be running MJ V4 so 11.9CR is do-able then? What would reliability be like?

 

Is the extra torque/power from the 2l+ worth the extra weight? OR do I just go D6B and 10.4:1?

[pug_ham 242 3 Cars]

Its not the block which gives the lower c/r but the mix of otherparts such as the pistons & head chamber volume.

 

I don't think swapping to a 2.0 iron block will give you any extra power than you can get from the same spec alloy block 1.9 engine, just the extra weight.

 

The higher c/r ratio wil have nothing to do with the reliability either, if its mapped in a competent person & everything else is right then it shouldn't be a problem.

 

Graham.

[mattbenselin 0]

I know that it's the piston dish which causes the lower CR that's why I either need to just swap my DKZ pistons for D6B and keep my block, or instead of taking the block apart just put a complete one straight in which is why I was thinking of other options.

 

So you reckon just go with D6B pistons and/or block and 10.4:1? Not worth the extra weight of XU10?

[pug_ham 242 3 Cars]

So you reckon just go with D6B pistons and/or block and 10.4:1? Not worth the extra weight of XU10?

Yes, I'd strip your engine & fit the correct pistons rather than swap to an XU10.

 

Graham.

[mattbenselin 0]

I had another thought...can you tell I'm getting no work done today!

 

1.6 pistons on the 88mm crank would give 11:1 on std GTI head, with my head 11.9:1? with the added bonus of keeping the weight down.

[DamirGTI 331]

As for me the best cost effective solution (if you fancy 8v unit) is :

 

1.9 DFZ block + 1.9 D6B head (preferably with a little bit of porting job or at least 3-angle seats .. and aftermarket cam , but it's not a must ..) + mappable ignition , tuned properly spark/fueling all together running on as higher octane pump petrol as possible ... that'll be nice engine (might add 1.6 flywheel and 1.6 box as well .. and , if possible budged wise , TB's or an pair of weber/dellorto carbs in order to get rid of the OE inlet manifold ..)

 

Damir

[mattbenselin 0]

I have pretty much that entire spec just which block to choose to get good cr with my head and optimal cc.

 

The DFZ block has 8.4:1 doesn't it, wouldn't it be better to start with something with higher cr?

 

edit: is the lower cr in DFZ engine through larger combustion chambers, they use the same pistons as 1.6...so essentially it's already a stroked 1.6 to 1.9.

Edited June 9, 2009 by mattbenselin

[James_R 3]

You have limited options with the head you've now got skimmed.

 

If you're going from scratch then you can alter the pistons to run the pistons you want. over 11:1 on std pistons is asking for trouble, although people have been known to run in to the 11.5 region, but nearing 12 won't last out really.

 

I'm running 10.5ish:1 on a 285 cam and seems fine, not sure you'll get any improvement adding compression.

[mattbenselin 0]

Adding my head to a D6B block will give me 10.4/10.5:1 with a 285 cam. How did you achieve 10.5:1?

[DamirGTI 331]

The DFZ block has 8.4:1 doesn't it, wouldn't it be better to start with something with higher cr?

 

Yes , but this engine/block has very high compression height and it reduces squish clearance .. it's the head which is crappy on this engine with deep chambers smaller valves etc. .. piston crowns are the same as 1.6 item with 9cc dish (15cc D6B pistons) so by bolting D6B head onto the DFZ block you'll get 11.1 CR

 

.. but the problem is because you have skimmed head so adding that one onto the DFZ block will result with CR higher than 11.1 mark .. how much is 40thou in mm's ?

 

Damir

Edited June 9, 2009 by DamirGTI

[mattbenselin 0]

40thou = 1mm

 

So you think because of the skim I should go with a D6B block to keep cr lower? This is what got me thinking of an iron block with 88mm crank as something a little different to norm!

[James_R 3]

Adding my head to a D6B block will give me 10.4/10.5:1 with a 285 cam. How did you achieve 10.5:1?

 

I'm using an XU7J4 bottom end and virtually unskimmed head chmaber size is the same 8v and later XU 16v's so I get the same CR. Lighter piston set up, over square conf and hopefully super revy's RR results coming soon.

[DjB 0]

I'm in the middle of building up a DFZ bottomend and DKZ head motor. No machining and a standard head gasket will see me having around 10.5:1 c/r. Combine that with a PeterT cam should make this a fun package.

 

I'm also building (PeterT is actually building it for me) a DKZ bottom end/crank with Mi16 internals (rods,pistons and liners). There will be some machine down on the deck of the block and a DKZ head with ITB. Cam specs haven't been discussed yet (I'm aiming for something fairly wild) but with this in mind I will be running a fully programmable ECU. The second motor I'm hoping to have a fitted early next year.

 

Time will tell,

 

 

Chris.

[mattbenselin 0]

Ok thoughts please, need definitive answer because I can't make my mind up....

 

Engine spec: see signature

 

Option 1: Alloy XU9 D6B block giving 1905cc and CR of +/- 10.4:1

 

.......Easy to do, lightweight but a bit 'normal'!

 

Option 2: Iron XU10 block giving 1998cc and CR of +/- 11.9:1

 

.......Again not hard to do, a good 20-30kg more! Option to use 16v head in future. Will I need different upper mount? How will the internals cope with 11.9 CR?

 

Option 3: Iron XU10 block with 88mm crank giving 2045cc and unknown CR?

 

......Swapping the cranks won't be hard but anyone care to estimate CR? Would the extra weight of using an iron block be outweighed by the extra performance?

 

Option 4: Iron block XU10 with 92mm crank giving ?cc and ?CR?

 

......This one probably not practical but thought i'd see if there were any takers!

 

 

With putting an 88mm crank or 92mm crank in an XU10 block would you need to machine off some block or do they drop straight in?

 

Cheers, Matt

[DamirGTI 331]

If you fancy torque and mid rmp kick rather than 16v rev nature why not to build turbo engine myself i prefer torque and power on mid rmp's rather than 16v engines shotgun rev nature ..

 

2.0 8v turbo engine (from Citroen XM , pug 605 etc. ) with good management would be my choice (or Mi16 with turbo but that'll be a bit pricey to build properly) .. to be honest i'm a bit sick and tired of atmo engines next engine which i'll be building will deffo be an turbo unit

 

Damir

[Tom Fenton 1,529]

As I've just found out, a suprising amount of power can be extracted from a turbo motor.

[DamirGTI 331]

Precisely ! and easily achieved than from the atmo engine , for the same amount of money turbo unit will always be one step forward ..

 

Damir

[Saveit 0]

Next one ill build when im done with my high powered 1.6 will definitly be a turbo... Probably rear mounted turbo..

[carbers205 1]

Matt, I can certainly comment on the XU10 with 88mm crank as I have done it!

I used a crank from an XUD9 but equally you could use one from any 1.9 petrol. The diesel crank only has 4 webs as opposed to the 8 of the 86mm petrol crank so worked out a little lighter. Dont know how many webs the petrol XU9 crank has.

The XU10 rods were a straight fit on the XU(D)9 crank so that is all good, had to machine approx 1mm off the top of the pistons though to avoid piston/head clash. You could prob get away with less than 1mm for super tight squish area but I never worked out how much less.

Final c/r was never worked out either due to the piston machining but the increased torque from the 2045 capacity and increased c/r was very impressive.

I ran this in conjunction with a D6B cam and lightened flywheel with light head work and 3 angle valves and seats and it actually managed on standard MM8P management.

One thing you will need to consider if swapping to XU10 is that the plastic inlet manifold will cause clearance issues with your 205s bonnet, options extend to ITBs or using the XU9 inlet with reshaped ports to match (XU10 head port is round and XU9 inlet is square). You would do well to keep the XU10 TB though as it comes with all the sensors you need.

 

HTH

Andy