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Guest Darragh

1.6 With 1.9 Head

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Guest Darragh

hello again!!

really stoked to be back on the forum again after loosing my last 205 to a fire 2 years ago. i have just picked up a mint white 1600 non-sunroof model for not much at all and intend on going the whole hog with this one (engine, suspension ect.). i intend on rebuilding the engine as its up on miles. i heard that putting a 1.9 head on the 1.6 engine will help as there are bigger valves. is this correct???

 

does anybody know if the combustion chambers are the same size on the 1.9 and 1.6??

 

thanks

 

darragh

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Baz

Nope, head's/valves are exactly the same.

Edited by Baz

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Guest Darragh
Nope, head's/valves are exactly the same.

so are the 1.9 pistons dished to overcome massive compression ratio?

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welshpug

what massive compression?!

 

yes the dish does differ slightly, its common to fit 1.6 pistons into a 1.9 engine to gain compression, but its not a massive amount.

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bensonmi
what massive compression?!

 

yes the dish does differ slightly, its common to fit 1.6 pistons into a 1.9 engine to gain compression, but its not a massive amount.

 

 

slightly of the subject but while every 1s talking about heads, can the head of a 2.0l turbo engine be used on a 1.6/1.9? would there be any benefit? surely it has bigger valves? using the standard non turbo manifolds of coarse and changing the cam, always wondered so i thought id ask!!!

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Guest Darragh

brilliant!!!

thanks for the fast replies!!

 

will porting the head give a noticable power increase? or am i just pissing into the wind?

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MrG

combined with other mods then yes, but on its own not sure.

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pug_ham
slightly of the subject but while every 1s talking about heads, can the head of a 2.0l turbo engine be used on a 1.6/1.9? would there be any benefit? surely it has bigger valves? using the standard non turbo manifolds of coarse and changing the cam, always wondered so i thought id ask!!!

 

Try a search for XU10 heads, they've been used before on both 1.6 & 1.9 GTi engines but not from the 2.0 turbo engine, just off the n/a XU10J2.

 

Graham.

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MerlinGTI

Early 1.6 heads had smaller valves than the 1.9 (XU5J)

 

Later ph 1.5 on had the larger (1.9 sized) valves (XU5JA)

 

correct me if im wrong?

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pug_ham
Early 1.6 heads had smaller valves than the 1.9 (XU5J)

 

Later ph 1.5 on had the larger (1.9 sized) valves (XU5JA)

 

correct me if im wrong?

No, thats right.

 

Graham.

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MerlinGTI

Intresting about the 1.6 pistons in a 1.9 lump, food for thought for my rebuild.

 

Can anyone elaborate please? (links, figures, pro's, cons', do's, donts?) sorry for hijack :(

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DamirGTI

1.6 pistons fitted inside 1.9 block will push the CR up to around 11.1 :( (but with 1.9 conrods of course) which is quite a bit high for today pump petrol octane rating and also for this our 205 dizzy ignition systems (apart from good fuel , you'll need to recurve the dizzy or fit mappable ignition in order to unleash full performance from such high CR engine)

 

As for the head job , it depends how well you're capable to prepare it , but don't expect much just from gas flowed head - ideally match few things/modifications together with gas flowed head like for instance - gas flowed head + carbs/TB , an nice camshaft , good exhaust system .. that will yield nice power/torque gains ..

 

Damir :(

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projectpug

Regarding what 1.6 pistons are like i used them in my old 1.9. As said very high compression on my track car i had to run 99 ron super unleaded with a couple of bottles of millers octane boost to stop it pinking. Does produce more torque though and on sandard cam will give more low down torque than stock but overall power will be about the same. Not worth it on a road car though as super plus octane bottles arn't too cheap.

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DamirGTI

I'm running mine on 98 RON petrol , and on H&H recurved dizzy to suit all the engine mods (but will stash the dizzy now cos i'll be fitting MS ..) now i dunno how the engine performs just with these 1.6 pistons fitted as i didn't try to drive the car with just this one single mod ... apart from fitting these pistons i've prepared the head , made some modifications on the inlet manifold and TB , adjusted the fuel pressure cos i've had problems with lean mixture conditions afterwards i made all this mods .. and some other bits and bobs ..

 

And i can say for sure that this engine now goes so much better that when it was std. , it's not just the torque gains , it feels and it is quite a bit faster than before , in term of both standing 0 to 60mph acceleration and in gear times acceleration , which is even more noticeable , and all that with a loads of torque trough all the rev range ..

 

From my experience the key for this "high CR operation" mod is good ignition system , and fuel quality/octane rating of course , but 98/99 RON is good enough providing that you tune up the engine properly (fuel mixture/spark advance) and keep the engine cool .. i've tried mixing Xylene (known as an very good anti knock agent ie octane booster used in the past in the 80-s in F1 , which is in fact main ingredient in most of production premixed octane boosters.. apart from these new MTBE ((methyl tertiary butyl ether)) or MMT ((methyl cyclopentandienyl manganese tricarbonyl)) boosters , that's another type of chemicals ..) and with roughly 1L of Xylene on full tank of 98 petrol i've been amazed how well this engine performs on good high octane fuel and how much spark advance it can handle when running on this mixture (well i dunno how much RON it was in the end but Xylene has octane rating of around 117-120 RON .. so it must be somewhere around 100/102 RON when mixed with 98 petrol ...) .. can try this for yourself but be careful cos Xylene is toxic !! (can use Toluol as well cos it's very similar , kinda like Xylene .. but again be very careful as both of these chemicals are toxic and Toluol is even reported as carcinogenic ! , so i prefer Xylene .. )

 

Damir :ph34r:

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taffycrook

I have a 1.9 with 1.6 pistons for the increase in CR.

You need to use the 1.9 rods which is often a problem, you need a press and a method of holding the piston without damaging it. Heat helps too.

Once again this simple but effective method of increasing performance has to be used in harmony with the rest of the engine.

Is there any point on an otherwise std set up? Not if you have to retard the timing so much that the gains are marginal.

Or have to use expensive fuel and additives.

However if you are planning on running maaped ign the benifits are worth the effort. The increased CR is a major advantage at part throttle. But ultimate gains will be all about how much ign adv you can get away with.

I used the pistons with a big cam, and the increase in CR should work well with this, however the draw back is in the cam timing I can only swing the cam a small amount this may prevent me getting the best timing possible with more TDC clearance.

So as you often find with tuning engines to gain in one area often means losing out somewhere else.

The trick is to find gains where the loss doesn't effect your particular application.

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DamirGTI
You need to use the 1.9 rods which is often a problem, you need a press and a method of holding the piston without damaging it. Heat helps too.

 

No need , quick and easy solution is using 1.9 DFZ pistons (from 205 1.9 CTi) as an whole assembly -> conrods are the same length as 1.9 D6B ones and pistons/piston crowns are identical to the 1.6 item (same 1.6 piston crown design/height and dish cc volume ..) .. ;) or could use flat top pistons from 1.9 SRi engine , but that will push the CR even more , over 11.1 value for sure :rolleyes:

 

Damir B)

Edited by DamirGTI

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MerlinGTI

Thanks for the interesting reading gents, that particular modifaction is unsuitable for my mildly tuned road car.

 

Still... nice to know these things :rolleyes:

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rex

The XU9 405 SRi had flat top pistons here in Fance.

 

Rex

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pug_ham
The XU9 405 SRi had flat top pistons here in Fance.

It did here in the UK along with the BX GTi.

 

I've got two sets of these pistons somewhere downstairs, one with rods still fitted & one without iirc.

 

Graham.

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