Polo Gti (AVY) Tuning Results (read further on)

[poussou]

Hi everyone,

I have recently installed the Schrick cams to my Gti but as it seems they are EXTREME when compared to the originals, so i would like to fool around with the camshaft timing to try and get the torque to move down a bit.

Anyone knows where i can get some adjustable gears for the Gti??

Looking around the web i haven't found much, Neuspeed makes some, but there is no descrimination among models.

Do the VW's all wear the same cam gears?I have put some links and pics so you can get the idea.


http://www.gprparts.com/brands/neuspeed/camGears.asp




http://www.autotech.com/catalog/cam_vt.htm

Cmon guys gimme a hand here

[Josh_PoloGTi]

Not sure mate... All I know is there are 2 gears!

Try Kent Cams as they make adjustable gears...

Good Luck!

Oh, what sort of power is your GTi making now? I remember you put those dr schrik cams in it... Is it hard to drive now?

[waynesGTI]

where did u get your cams from? cuz my cam belt needs changing soon and i would like 2 fit some cams 2 my GTI when i have it all apart thanks!

[workinprogress]

adjustable cam gear for polo avy and needle in haystack pretty much the same thing been looking for some for ages now problem is one pulleys got 2 belt gears on so trying to get a adjustable bit of kit for them is hard as

[dubpolo]

Hi everyone,

I have recently installed the Schrick cams to my Gti but as it seems they are EXTREME when compared to the originals

what do you mean by extreme? i was looking for some but you may of just put me off!

[poussou]

Hi everyone,

I have recently installed the Schrick cams to my Gti but as it seems they are EXTREME when compared to the originals

what do you mean by extreme? i was looking for some but you may of just put me off!

Well....Here's the deal...

My advice to you is DONT DO IT, if you are not prepared for some MAJOR changes to the engine along with it....

There has been an EXTENSIVE discussion in another (greek) forum about this tuning by me and we have dicovered that the actual cams are as i said "extreme" for the Gti.According to WinElsa the Gti's original cams are 205 int. / 215 exh. while the Schricks are 256 int./ 244 exh !!

This, along with th installation of a BMC CDA has made the car TOTALLY different in its behaviour.Also to mention the car IS CHIPPED (cause i couldn't really imagine what it would be like ifit wasnt)

There is a huge shift of torque to the higher rpm's which makes the driver having to keep it always above 3000 rpm (during acceleration ) just to get the car to be responsive.Stepping on the gas in 2 or higher gear instantaniously from idle, has NO EFFECT.The is a lag phenomenon which i can't only atributte to the E-GAS thing.

The reasons for this (as i have figured out after LOTS of hour of reading on how engines work) are or moght be the following.

The increased cam duration has changed the timing of the valves which makes 2 things happen
a)The so called "effective compression" is lower now, making low RPM torque obsolete
b)The current ECU programming isn't sufficient to deliver the right advance for the low RPMs hence the car "lags"

I haven't been able to discreminate between the above yet, since what is necessary is a)a cranking compression test and b)a dyno session to determine the A/F ratio and necessary advance.

I was ready (and still am) to take the car to a dyno tuner for it to be programed on the dyno, but then it occured to me that the best thing would be to settle the compression ration first and then rechip the car.I am at this stage now thinking of what i should do.

The solutions to the above problems are as follows..

1)Increase effective compression by
a)Skimming the head.(As far as i know noone has done that and can't really tell how the Gti head will react to that.It is known the compression is pretty high already but due to the high compression pistons.Don't know how far i can skim of it without it being dangerous...)
b)Changing the gasket to a thinner one (AFAIK the Gti has a competition gasket and don't know if i can get a thinner one...Maybe you guys can help me out...)
c)Installing adjustable cam gears, which would have the effect of timing the cams to open and close the valves quicker, in effect reducing the cams duration and thus shifting the torque curve to lower rpm's, losing some top power.

Having said all that, i do have to stress the car behaves AMAZINGLY above 3000+ RPMS.The acceleration with 2nd gear from 3000 to redline is UNBELIEVABLE .It almost feels like the car is turboed !!!Power ahs shifted as i said and specially when the VVTi kicks in its hell.Engine sound has changed also with a racing sound in all the rev range.I guess it turned form a German one to a....Japanese ???

So as i said, if you are not prepaired for major changes (since i know most of you guys haven't even chipped that car) don't try it.They won;t work as direct bolt-ons.But if you do decide and the stuff along with it....IT GONNA BE ONE HELL OF A POWER GAIN .


Sorry guys...I'm alone sailing in uncharted waters here...I learn as i go along....

P.S. @ Josh....The car as i said above has change completely.I do have to say it has given me LOTS OF SMILES as it is right now Its just that you don't get the feeling of completedness if it doesn't behave fully as you want it to.I guess we can't have both (torque and power) in this N/A world.I am estimating it should be close to 145+ right now.But since i haven't dynoed it and seen ppl with Lupo's making 135+ stock, i can't really tell.A +15 hp difference from stock is a safe bet i guess....

[dubpolo]

So what you are saying is

-Above 3000 RPM the car is spot on!
-Below it is slower

So off the line in first the acceleration is reduced because of the "lag" but from then on with quick gear changes the acceleration is allot better.

(the same as a turbocharged car?they get all there power at the top end of the rev range)

If I changed the cams in my car and at the same time got the ECU re-mapped to try and compensate for the lag then the car would be ace!

What would gas flowing the head do? Would that help?

[poussou]

So what you are saying is

-Above 3000 RPM the car is spot on!
-Below it is slower

So off the line in first the acceleration is reduced because of the "lag" but from then on with quick gear changes the acceleration is allot better.

(the same as a turbocharged car?they get all there power at the top end of the rev range)

If I changed the cams in my car and at the same time got the ECU re-mapped to try and compensate for the lag then the car would be ace!

What would gas flowing the head do? Would that help?

Well here is the thing now...I really can't tell you that, cause i am in the stage of investigating that also !!!

I am hoping skiming of the head won't be necessary, and all the...artifacts are caused by the bad stage 1 program.Hopefully the "lag" is caused by the great difference in the manifold pressure due to the longer duration, OR cause the car is really lean down low so to prevent detonation the ECU reduces the spark advance thus the late response.

Here is the problem though....Dyno programming is gonna cost me upwards of 600 Euro, according to the "dyno hours" i'm gonna need.
BUT...What happens if what i really need is more compression and its not the fault of the existing programming???All the cash is gonna go down the drain with NO RESULT besides perhaps smoother curve and better A/F ratios.After talking to the programmer he advised me to finish up the rest of the modifications cause a new remap isn't for free

And so i'm stuck, and any advice would be by guess only.

As far as the porting goes...I heard somewhere the head was designed by Williams Racing and there isn't much room for improvement, or even worst spoiling the flow.But if you have decided to do it, go ahead and skim the head also cause you're gonna need it.Better yet find a thinner gasket and tell me where to buy it from also..

The cams are not a bad upgrade.Quite the contrary.It all depends on what you want.I've had 1.0 lt cars pass me by on uphill roads and that wasn't much fun...Of course on a drag stip setup the car flies, eventhough programing is still a must...

What do you guys think i should do ???

[dubpolo]

if you want to do more work to the car get this done befor the re-map! i got a price for the re-map

-£350 done by AMD, the man said i would ONLY get a gain of 10-15BHP he's used to getting huge gains by re-mapping turboed cars

[poussou]

if you want to do more work to the car get this done befor the re-map! i got a price for the re-map

-£350 done by AMD, the man said i would ONLY get a gain of 10-15BHP he's used to getting huge gains by re-mapping turboed cars

Hmmmm...Well my forum friend...It seems you are not much of an expert on the subject of tuning, so my advice to you is to just enjoy the car as it is, since messing with it will only put you through much trouble....

And another thing...If you really believe chipping will give you 15 HP you have another thing coming.EVEN I (with all the stuff already on the car) doubt i gained 20 HP.Imagine you and a stock engine....

[dubpolo]

no i don't know, well anything about tunnig , but i do want more power so i can enjoy driving even more! these where his words not mine! i was just saying that for £350 i would be more than happy with an extra 10BHP.

good luck with getting this sorted and keep me posted on how it goes! i let people like you do these things first, then you tell me what i need to go and buy!

[JWC]

Be very careful when making any of these mods, as he says, the stock engine is designed very carefully, if they could get more power out of their design without compramising talk and making it drive awful, they would have done.

The Cam lift design is very specific, people assume that higher lift gets more power, but as already discussed, over the rev range the actual amount of acceleration you get it pretty constant, as you end up trading something. Its the same with hi-flow exhausts, or induction kits. The OEM design isn't just stuck on your car for fun, it took thousands of hours to design. The backpressure and induction pressures are very carefully calculated for every RPM under every type of load, at all tempereatures, pressure and humidities. None of the after market stuff will have any of that. So whilst you gain a couple of HP and 6000 RPM you lose driveablility and in some cases increase wear on the engine components dramatically. The more you know, the more you'll get put off. Everyone would always like a little more power. Even the pilot of an f18 super hornet is thinking, just a bit more power, from his 86,000 HP engine!!!

[poussou]

Be very careful when making any of these mods, as he says, the stock engine is designed very carefully, if they could get more power out of their design without compramising talk and making it drive awful, they would have done.

The Cam lift design is very specific, people assume that higher lift gets more power, but as already discussed, over the rev range the actual amount of acceleration you get it pretty constant, as you end up trading something. Its the same with hi-flow exhausts, or induction kits. The OEM design isn't just stuck on your car for fun, it took thousands of hours to design. The backpressure and induction pressures are very carefully calculated for every RPM under every type of load, at all tempereatures, pressure and humidities. None of the after market stuff will have any of that. So whilst you gain a couple of HP and 6000 RPM you lose driveablility and in some cases increase wear on the engine components dramatically. The more you know, the more you'll get put off. Everyone would always like a little more power. Even the pilot of an f18 super hornet is thinking, just a bit more power, from his 86,000 HP engine!!!

Well there is some logic to what you are saying but its not all true.

The fact is that Automobile manufacturers have VERY strict guidelines to follow when introducing a new car to the market.Guidelines imposed by the E.U. as a part of its cleaner enviroment initiative.Thus the AVY engine is Euro 4 rated whilst the ARC engine is not.

The specs of a camshaft are designed with not only best output in mind but also economy and emissions.But after the car has left the factory noone is stopping you to unlease the full potential of an engine (of course still trying to keep polution to a minimum).

There is also another factor that comes into play.Thats the WIDE limits manufacturers put on an engine to make it work well at ALL conditions.This means it will run on 98 gas but also wont EXPLODE on 95 gas.And this is where chipping the ECU comes to play.If you promise to be a good boy and feed your car ALWAYS 98 gas, the programmer adjusts the managment accordingly to give you a few more hp.

But remember this is not magic.There are limits as to what a program can do...And then the rest of the mods come into play....

And as with ALL the things in life.. If you don't mess with it....You won't learn....

[JWC]

Well yes, the emissions obviously stiffle the car quite a bit, can't breath can't run too rich, can't do this can't do that. There are of course limits to the mods though, like you can't really remove the cat etc. I supposed making everything lighter is a good way to go, and ensuring that the intake charge is as cold as possible.

[twisty b-road]

I'm looking into this at the moment (it's an AVY Lupo though but there is always good info here)
I have some doubts as to whether the Schrick 256 degree are extreme enough for what I want. I should say that I don't mind loss of low rev torque. 170bhp at 7500rpm has been done in Germany
I have e-mailed Schrick and spoken to a few Shrick suppliers, but cannot get an answer as to why 256 is the most extreme profile they offer. Looking at other engines, conventionally speaking, I would be looking for a late 260/early 270 profile. It has been suggested to me that 256 is the most extreme profile they offer due to the variable timing on the inlet cam. I wish I could find out/understand for certain
A set of custom made piper cams would be over £1000, I didn't bother calling Kent or Cat as I thought the price would be the same
In my opinion replacing the cams and then not remapping the ECU will never extract the full potential of the cams as the engine still believes it's running the mild standard profile.