detuned 1.9 205gti
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  1. #1
    Member Cosmo's Avatar
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    detuned 1.9 205gti

    I know this question has been asked a thousand times, but I'm pretty new to all this stuff......however......I have a lovely 205 gti 1.9 model that apparently was detuned before coming to the land of Oz to run on 91 octane unleaded.
    Now the problem is can I easily re-tune it to run better on Optimax.....
    I have ported the air intake & used a bigger butterfly.....as well at added a 2.5 inch exhaust with a figh flow cat.
    evil
    Would I require new pistons, new euro spec computer, new cam, shave the head? What did the French do to detune it in the first place ?

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    Cosmo
    1993 205 GTI
    2009 MX5

  2. #2
    1000+ Posts PeterT's Avatar
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    Three things spring to mind:

    1. Compression - difficult to improve unless you fit pistons from a series 2. Shaving the head will not result in a significant enough improvement, to take advantage of 98. Perhaps a skim and an icrease in ignition advance down low will see some improvement. Skimming OHC heads usually retards the valve timing, and often there is not enough metal there for a decent shave like in the good old days.

    2. Valve Timing - the timing is retarded 4 degrees crank, to improve emissions, by way of a different pulley. Three choices here; vernier pulley, original UK pulley or offset key.

    3. Cat. - fit a high flow after market unit, say from a 5.7L V8, if your environmentally conscious, and/or worried about the law. Otherwise, knock the centre out.

    I doubt a 1.9L engine can flow enough at 6000RPM to make use of a 2.5" exhaust. I would have used 2.25", and enjoyed the extra torque.

    These are the cheap alternatives. The rest costs more money. I can help with progammable ecu's if you want to go that far.

    '92 205 Mi16
    '90 Mi16x4

  3. #3
    Member Cosmo's Avatar
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    Thanx for your reply PeterT.........I have heaps to consider.....whether or not to rebuild the original motor......it's smoking by the way.....replace it with a post '92 motor.....or put in a 306 donk...apparently the standard 1.8 has more power & torque.....however it may 'de-value'the car, ie not original anymore. Will a 'Unichip' piggybacking the ecu work just as well ?
    1993 205 GTI
    2009 MX5

  4. #4
    1000+ Posts PeterT's Avatar
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    I haven't had any experience with Unichip, but see my reply in the 405 Peugeot section.

    '92 205 Mi16
    '90 Mi16x4

  5. #5
    Fellow Frogger!
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    cosmo,

    I was in the same situation as yourself with my 205gti
    I opted to put a series2 engine in it (Makes the world of difference)
    I would advise on rebuilding what ever option u take (Low k engines r rare these days)
    I have a 2.5 inch stainless steel exhaust system on my car and like PeterT said u will loose a bit of torque down low but boy does it go up top.

    Murat

  6. #6
    Member Cosmo's Avatar
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    Thanks Murat,

    You have inspired me. I'll have to price out my options & go for the best one. The engine has a genuin 113,000km on it. I bought it from these enthusiasts in Nowra (country NSW)over the internet......risky business.
    I have considered making the car lighter, ie taking out the aircon & the electric window hardware.....power to weight ratio you know.
    Would you know if I have been wasting my time by using Optimax & the like........would it make a difference in the performance on a detuned engine ?
    Cosmo
    1993 205 GTI
    2009 MX5

  7. #7
    Fellow Frogger!
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    Cosmo,

    Your correct running optimax is a waste of money with the detuned series1 engine.
    I have the series2 engine and still only run premium unleaded when i can.
    Usually i am running mobil 98 ron synergy 8000 (But remember i am running a little more compression than u and most likely a little more ignition advance (I don't get any pinging in any situation)
    Optimax is a slower burning fuel and is ideal for the high compression engines running bit more ignition advance from the factory settings for a little more crisp throttle response.
    Talking about weight my car is around 835-850kg depending if i am at the track with no spare or on the road with it.
    My aircon is completely removed (I like a basic car that easy to work on)
    I used to have a lot of fun with 4cyl late at night coming home from the city and have not lost to a normally asperated 4 yet these r some of the cars i have run.
    Some of the interesting runs were
    Suzuki swift gti (This guy pulled me over and thought i had a turbo)I let him know i have a big 4 cyl with great power to weight.
    The closest run i have had was with a 4cyl
    Diahatsu Detomasa 1.6L 122hp from the factory just managed to pip him after he got a smile on his face with his fwd lsd (This guy was poker faced)But what a great little car)
    I have also been left for dead buy a silvia sr20 turbo that has been extensively modified.

    goodluck with your 205
    Murat

  8. #8
    Member Cosmo's Avatar
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    Morat..thanks for the info.....again.

    I'm going back to regular unleaded.....
    Apparently what they do in Europe to get the 205's faster at bottom end, is to replace the transmission with the 1.6's...electric take off .....however the top end will ultimately suffer.

    I think I'm going to look for a replacement series 2 engine......it is sounding like the simplest solution....& I'm not planning to sell the car....whoever's nice to me will inherit the beast when I die.

    The aircon will go, cos my fan has never worked & I replaced both the fan itself & the heater control unit in the dash.......I think this may be a common problem.

    How funny.....I too drive without the spare & love surprising the competition especially around twisty roads.....

    I have recently got hold of a set of new 15inch (originals) & with 195/50 tyres have completely transformed the handling & roadholding... tongue
    1993 205 GTI
    2009 MX5

  9. #9
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    Hi!
    Before I bought my Reno 5 GT Turbo I wanted one of those 205 GTI. I like ligth and powerfull cars. I also have VR6 Golf 4 door.Next car will be 2 door VR6 Turbo Golf. Good luck with 205 GTI!

  10. #10
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    Hey Cosmo,

    I wrote a reply in the 106 discussion before i read this one. I put a series 2 motor in my S1. it had 100k on the clock and i had a drive of the car before it was taken out (too make way for Mi16 motor). Always wanted a S2, but didn't have the cash, so got the disc rear end, and this S2 motor. When the head gasket went on my S1 motor that was the perfect opportunity to take it out and put the S2 in. I dont have aircon anymore either. The car should be lighter than a S2, no aircon, no power steering, smaller wheels and shorter gearing.

    My car seems to run better on BP ultimate, rather than optimax. Did noy know that Mobil premium was 98RON. Theres a new one at the moment, i think Caltex. 'Evolution', 98RON. Didnt try it.

    If you look in the back of one of the little handbooks in the glovebox (if your glovebox has not been overtaken by the fuse box like mine and the books are not lost) it says that a dealer could do the detuning to run on 91RON. Does that mean that it wasn't a terribly complex operation? A matter of altering the computer management? A car that runs on 91RON is handy on long trips to Adelaide and the like, when premium is rare.

  11. #11
    1000+ Posts PeterT's Avatar
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    Shoj,
    the 205 ignition advance can be atltered by rotating the distributor housing, thus making it more tolerant to low octane fuel. Unlike Mi16, which had totally integrated ECU, with a knock sensor.

    '92 205 Mi16
    '90 Mi16x4

  12. #12
    Member Cosmo's Avatar
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    Hey Shoj & PeterT,
    thanks for the info......how much was the S2 engine.....if I may ask ? I'm also happy to hear that the S1 gearing is shorter than the S2 & the car is lighter.......many people that I speak to always bag the S1 as the "bad" series.....I'll have to prove them wrong....& beat them at the lights.

    What I've also done to mine is take out the door panelling & the back panelling & glued to the metal panels sound deadning material....making sure to keep clear of drainage holes & where water may flow.......the results are instant....the car sounds more solid, there is less intruding road, tyre & wind noise....but still the nice drone of the engine & exhaust.... A cheap & easy sunday arvo project.
    Cosmo
    1993 205 GTI
    2009 MX5

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