S2 205gti power gain options?
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  1. #1
    Tadpole
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    Default S2 205gti power gain options?

    hey guys i currently have a 91 s2 and am looking to try and get the power output from 75kw to the 90kw that the s3 and eu spec ones are. I am having great trouble finding info and making sense out of what i can find.

    What is the best option to get more power out of the 205gti dfz and maintain reliability and drivability? As far as im aware the power diffrence comes from the compression diffrence. Is it possable to buy a s3 head and put it on a s2 block to make the diffrence up? If so what els must be changed? cam? head gasket? managment?

    I have also read that the si head and the s3 head are the same. Is this true and if so would it be a better/cheaper option to go for that?

    Failing the above would it be a better option just to work on the existing dfz head because i am craving some power and i need to make up the 15kw diffrence before i can sleep at night

    please help me work out the best way to get some s3 power. Thanks in adavance.

    BTW: car seems to need the seals done so the head will need to come off regardless.

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  2. #2
    1000+ Posts Dave's Avatar
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    Yes, you can put a s3 head on your dfz block. This will give you bigger valves, a smaller combustion chamber and a lot more compression than even the uk 205's. With std management you might get a bit of pinging at low to mid revs, but it makes for a lovely engine.

    Dave


  3. #3
    1000+ Posts Dave's Avatar
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    Use the camshaft from the s3 engine while your at it. More duration than the earlier item.
    When you reco the series 3 head, get some 3 angle seats cut and back cut the inlet valves.
    The casting of the bowls in the s3 ports is not really pretty you can grind it to have nice smooth curves using a die grinder (or if your cheap a drill and some carbides).

    Dave
    Last edited by Dave; 28th January 2006 at 07:42 PM.


  4. #4
    1000+ Posts Dave's Avatar
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    Here is a pic of a s3 inlet port before and after porting.



    After:



    You can see the big dip behind the valve guide is ground out for a really smooth curve.

    Dave


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    1000+ Posts PeterT's Avatar
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    Whilst the S3 head is a good option, you can do just as good by skimming up to 2mm off the DFZ and getting a 3 angle valve grind. You can also regrind the std. cam. I have a grind that works well with the extra compression. The end result is approx. 140-145hp.

    '92 205 Mi16
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  6. #6
    Tadpole
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    ok sounds easy enough if there are no other modifications required?

    Also how does this compromise the reliability of the car? i was told some myths that the 205gti's throw pistions often when pushed hard? If i do put the s3 head on will i be compromising reliability or do many people do it and not have too many problems?

    Can anyone confirm that the s3 head is the same as the si head?

    Has anyone done this modification before? and what steps must be carried out?

    How hard is it to find a s3 head?

    Does shaving 2mm off the original head make a more effective modification over finding a s3 head?

    What is the more cost effective option?

    Sorry about all the questions guys but i wanna get the ball rolling if im going to do it lol.....

  7. #7
    1000+ Posts Dave's Avatar
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    My Bx GT has that exact combination, s1 block with s3 head. I was just lucky enough to have a spare s3 engine to pull apart. If all you have is a s1 engine then just do the big skim, the ports are smoother in them to start with, and the valve size does not make a big difference.

    If you go through with this, make sure you get Peter to regrind your cam - no point having all that compression if your not going to make use of it.

    Also if you are doing a big shave, you will need to get an adjustable camshaft sprocket (because you are reducing the distance between the crank sprocket and cam sprocket and therefore are retarding the cam timing), talk to peter, he can probably make you a re-keyed sprocket.

    Dave




  8. #8
    1000+ Posts parry's Avatar
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    Quote Originally Posted by vespa
    ok sounds easy enough if there are no other modifications required?

    Also how does this compromise the reliability of the car? i was told some myths that the 205gti's throw pistions often when pushed hard? If i do put the s3 head on will i be compromising reliability or do many people do it and not have too many problems?

    .....
    I have been racing a DFZ now for over 2 years. Stock bottom end with the Peter T mods and the engine still starts first go and still has high compression. The stock bottom end has now seen 400 laps of full throttle with no problems.
    90 205 Gti Cherry Red(Track Car)
    2009 207gti
    1985 505gti (Shitbox Rally) Sold

    PBs:

    Oran Park: 1:27:9
    Wakefield: 1:05.6 (July 2015)
    Eastern Creek: 1:47 (16V) 2019
    Mt Huntley: 34.44 (2004 stock 205)
    Ringwood: 35.06 (30/10/2005)
    Winton: 1:33.6 (2017)

  9. #9
    1000+ Posts Dave's Avatar
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    The DFZ is definately a good little engine, my bottom end has never been apart, and has put up with very spirited driving from me for the last 5 years.

    Only difference between the dfz and dkz block is the pistons really. The dkz has a bigger dish in the piston (lowering compression) but concentrates this dish below the spark plug. This squishes the mixture close the the spark plug for a more efficient and faster burn. I believe the higher compression from the dfz pistons is more important though.

    Dave


  10. #10
    al
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    Quote Originally Posted by PeterT
    The end result is approx. 140-145hp.
    Does this move the power up the rev range, or does it remain good down low? (and what power do ours have standard - how many hp is 74kw?)

    I've been looking into buying an Mi16 soon and rebuilding it, but i have already spent a fair bit on my engine and it would be nice to keep it. I suspect it needs the cam seal done, (it looks a bit wet around there) so while the belt is off i could probably justify putting a worked head on...

    It is interesting how much more powerful the S3 cars feel though. I drove one last week and was really suprised...
    405 Mi16 - Sold - Now back
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  11. #11
    1000+ Posts Dave's Avatar
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    Increasing compression will give you more power down low as well as up in the rev range. By adding longer duration/higher lift cams, you move your peak torque up in the rev range and therefore compromise on low end power. My GT has a 272 degree cam ([email protected]) and still has much more bottom end torque than any other xu9 engine I have driven.

    Your std engine is about 105hp.

    Dave


  12. #12
    al
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    Quote Originally Posted by Dave
    Increasing compression will give you more power down low as well as up in the rev range. By adding longer duration/higher lift cams, you move your peak torque up in the rev range and therefore compromise on low end power. My GT has a 272 degree cam ([email protected]) and still has much more bottom end torque than any other xu9 engine I have driven.

    Your std engine is about 105hp.

    Dave
    Is peters 145ish figure refering to parry's car with the quads? That seems like a huge increase...

    And a bit more power up the top would be nice. This is sounding really attractive now, so when (if) the 405 sells, i think i get it done.
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  13. #13
    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by al
    Is peters 145ish figure refering to parry's car with the quads? That seems like a huge increase...
    No, that's just with a std. TB and manifold. Parry's has approx. 160-165hp.

    '92 205 Mi16
    '90 Mi16x4

  14. #14
    al
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    Quote Originally Posted by PeterT
    No, that's just with a std. TB and manifold. Parry's has approx. 160-165hp.
    If i can pull that much out of the 8 valve, it certainly puts me off dropping a standard 16 valve in. While it would be more tunable in the long term, if quads get 160ish that is heaps...

    If i wanted this done, (with one of your cam grind) would it be possible to send a complete head up to you and get it sorted peter?
    405 Mi16 - Sold - Now back
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  15. #15
    Fellow Frogger! Cubits's Avatar
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    Quote Originally Posted by al
    It is interesting how much more powerful the S3 cars feel though. I drove one last week and was really suprised...
    I find the S3 feels a bit lethargic and lumpy below 2500rpm compared to the S1, which suprised me considering the advancement of the ECU control and improved compression. But once you get into the meat (starting at 3k) it feels like the torque just keeps building, all the way to the limiter. The S1 still hit 6k well, but you could definitely tell the party was ending early.

    Also, i'm not sure if the S3 has slightly worse throttle response than the S1, it seems to hesitate for a fraction longer (of course, i could be imagining it).

    It is piles faster than the S1, and it's proving more fuel efficient too (same gearbox). Don't think i'll get tired of this engine for a while.
    1987 205 GTI - Graphite Grey - 206k km's
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  16. #16
    1000+ Posts parry's Avatar
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    Quote Originally Posted by Cubits
    I find the S3 feels a bit lethargic and lumpy below 2500rpm compared to the S1, which suprised me considering the advancement of the ECU control and improved compression. But once you get into the meat (starting at 3k) it feels like the torque just keeps building, all the way to the limiter. The S1 still hit 6k well, but you could definitely tell the party was ending early.

    Also, i'm not sure if the S3 has slightly worse throttle response than the S1, it seems to hesitate for a fraction longer (of course, i could be imagining it).

    It is piles faster than the S1, and it's proving more fuel efficient too (same gearbox). Don't think i'll get tired of this engine for a while.
    The main reason the S3 seems lethargic is because of the gearing. What you need is S1 S2 c&p and the 90kw is trasformed into a monster. Or you can go the 405 c&p of 4:11 and really feel the torque.
    90 205 Gti Cherry Red(Track Car)
    2009 207gti
    1985 505gti (Shitbox Rally) Sold

    PBs:

    Oran Park: 1:27:9
    Wakefield: 1:05.6 (July 2015)
    Eastern Creek: 1:47 (16V) 2019
    Mt Huntley: 34.44 (2004 stock 205)
    Ringwood: 35.06 (30/10/2005)
    Winton: 1:33.6 (2017)

  17. #17
    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by al
    If i wanted this done, (with one of your cam grind) would it be possible to send a complete head up to you and get it sorted peter?
    Yes, that's the best way to do it, as the cam needs to be set up on the head. In a sturdy wooden box, it costs approx. $20 to send the complete head. If you're not a competent woodworker, I can send you a box just to make sure it arrives safely.

    '92 205 Mi16
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  18. #18
    al
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    Quote Originally Posted by PeterT
    Yes, that's the best way to do it, as the cam needs to be set up on the head. In a sturdy wooden box, it costs approx. $20 to send the complete head. If you're not a competent woodworker, I can send you a box just to make sure it arrives safely.
    I've already got one of your boxes...

    Anyway, when my 405 is sold i will be in touch. The prospect of pulling the engine out and doing another swap doesn't fill me with joy...
    405 Mi16 - Sold - Now back
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  19. #19
    1075.6 SamR's Avatar
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    I will at some point in the nearish future be after some more power for my 205. But I don't want to lose the great low rev torque that makes for a good road car. I assume that this is achievable with an increase in compression ratio (without going overboard) and a suitable cam?

    On another note (I guess you could say it's related to 205 performance), al, you mentioned handbrake turns in 205s in another thread recently. I had to do a u-turn on gravel today out at Oran park raceway, and thought, "Why not?" They certainly do turn around on the spot. Very easy to do and very controllable, I had a blast.
    2005 Renaultsport Clio 182 Cup
    1989 205 Gti - Sold


    "This year, I invested in pumpkins. They've been going up the whole month of October and I got a feeling they're going to peak right around January. Then, bang! That's when I'll cash in." - Homer Simpson

  20. #20
    al
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    Quote Originally Posted by SamR
    On another note (I guess you could say it's related to 205 performance), al, you mentioned handbrake turns in 205s in another thread recently. I had to do a u-turn on gravel today out at Oran park raceway, and thought, "Why not?" They certainly do turn around on the spot. Very easy to do and very controllable, I had a blast.
    You had to do one... right.

    The things are insane for swapping ends. (I love the fact that you can pull it off in skinny streets to avoid 3 point turns!) I am trying to kill the tyres on my car (they are less than 1k kms old and too harder compound for my liking) in a hurry, and my technique is improving.

    When you get confident, try doing it with a bit more speed up... (although beware of running into things, obviously) I can get mine doing 180s nicely when it is wet in my work carpark...

    Watching the monte carlo round of the wrc has me all inspired now...
    405 Mi16 - Sold - Now back
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    1075.6 SamR's Avatar
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    Quote Originally Posted by al
    You had to do one... right.

    The things are insane for swapping ends. (I love the fact that you can pull it off in skinny streets to avoid 3 point turns!) I am trying to kill the tyres on my car (they are less than 1k kms old and too harder compound for my liking) in a hurry, and my technique is improving.

    When you get confident, try doing it with a bit more speed up... (although beware of running into things, obviously) I can get mine doing 180s nicely when it is wet in my work carpark...

    Watching the monte carlo round of the wrc has me all inspired now...
    Yep, I had to turn around and go back the way I came, and knowing that the turning circle isn't too fantastic, I gave the handbrake a go. I haven't done any on sealed surfaces yet. I don't want to chew up my tyres too much... Maybe, OK, definitely when it's time to replace my tyres
    2005 Renaultsport Clio 182 Cup
    1989 205 Gti - Sold


    "This year, I invested in pumpkins. They've been going up the whole month of October and I got a feeling they're going to peak right around January. Then, bang! That's when I'll cash in." - Homer Simpson

  22. #22
    Fellow Frogger! nos205gti's Avatar
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    nos kit....

  23. #23
    1000+ Posts Luca's Avatar
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    I've worked my head and am very happy with it. I spoke to PeterT first then asked what could be done from a head guy and finally took it in to a place that has racing experience in Vic. (Harrop Racing).

    If I were you I'd take the whole car to PeterT and get him to do it all. It'll be the ducks nuts when he's done with it.

  24. #24
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    Who is this peterT you speak of?

    I am look ing to get a whole lot of work done to mine, (refreshen a lot of running gear, not motor) and want a good mechanic, rather than do it myself.

    Regards,

    Byron

  25. #25
    Fellow Frogger! Cubits's Avatar
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    Quote Originally Posted by parry
    The main reason the S3 seems lethargic is because of the gearing. What you need is S1 S2 c&p and the 90kw is trasformed into a monster. Or you can go the 405 c&p of 4:11 and really feel the torque.
    But i do have an S1 gearbox! I've been comparing engines in the same car, so the only variable is the engine, and the S3 is definitely less sharp below 3k than the S1.
    1987 205 GTI - Graphite Grey - 206k km's
    1988 MR2 Supercharger - Mica Blue - 114k km's

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