Modify boost return valve to increase performance?

[G_Power 10]

Hi everyone, this is my first post on this forum so go easy on me!

 

I'm from the UK but now live in Cape Town and recently picked up a stock G60 Corrado. I've been bringing it back to life over the last few months and have got to the stage of increasing HP.

 

Everyone seems to have good things to say about a smaller pully and chip as a starting point. As the engine uses more boost than it needs ,most of the time, would another way to improve HP not be to modify the linkage between the throttle body and the boost return valve? Obviously a chip/remap would also be required. At what RPM does the engine require more boost than the charger produces?

 

Have any of you ever tried this? Am I barking up the wrong tree? Would be interested to here your thoughts/experience.

[mimjed 0]

if your going for a power hunt, 68mm pulley, shaving down the fins on the supercharger outlet, port the throttle body and fit cams, fit fmic, then go for a map.

 

Some like/some don't - delete the boost return pipe to keep cool charged air only going into intake.

 

Have fun :)

[G_Power 10]

That's pretty much what I was/am planning but more power comes from more air and fuel, if the charger is producing more air (even with the boost return deleted the excess air is vented to atmosphere) than the engine can use (apart from at or close to WOT) then surely reducing the amount of pressurised air that is recirculated will allow for more fuel which should give more power.

 

If I'm onto something here then it would potentially improve a setup that already has a smaller pulley (after a remap)

 

Thing is where I am these cars are feck'n rare so parts are impossible to get, no way I'm gonna mess around with something unless I'm sure it's gonna work

[G_Power 10]

No other comments on this?

[Album56 0]

The adjustment of the linkage on the boost return is critical to driveability of the car & should not be altered, other people have tried it without much success. Best way to increase power & make car feel more responsive is the tried & tested smaller charger pulley & chip & mine has a valve in the ISV plumbing to stop it dumping boost aswell.

[Riley 0]

At what RPM does the engine require more boost than the charger produces?

 

It never does :thumbleft:

 

After a smaller pulley/chip/cam/fmic etc it's probably time to actually make use of the boost via better flow, head work and whatnot. Aim for a lesser boost reading which equals better breathing ;)

[G_Power 10]

@ Album56 that is exactly my concern, whilst the theory seems to have merit I don't want to bugger anything up in terms of driveability. Perhaps the only way this could be managed properly would be a modern fly by wire setup with the ecu controlling the boost valve. Outta my budget and level of expertise!

 

@ Riley - I'm not sure I agree when your at WOT but that's what got me thinking about adjusting the boost valve in the first place. Essentially what we are doing is taking an engine S/C setup where the engine can never (or rarely) use all of the boost available.

 

this means that most of the boost is being recirculated most of the time?

 

Then we go and stick a smaller pulley on creating even more boost that the engine cannot use?!? It just seems a very inefficient setup

 

What sort of gains do peeps see if they leave the pulley alone and just get a new chip?

[Redfox 10]

Just thought I'd chip in with my thoughts,

 

On late G60 engines (mine is a 1991), the cylinderhead is ported both in and out, together with ported manifolds. Mine is stock standard, and is rolled conservatively at 178 Hp. When I later on made my own 2,75 inch complete exhaust including a special flowed cat, I now have 192 Hp, while still being able to get a really good milage, if I don't press the pedal heavily.

 

There are other small Things to do. The rallye/street cam, assymetric, is giving good power. The Little throttle blade can be changed to a better flowing one, and the Black plastic lunchbox can be deleted.

The snorkel inside the airbox can be taken out, but keep the connector to the front. Or cut it shorter. Better airflow, as the air don't have to turn, right in the middle of the flow.

Remember to run in your g-lader slowly at idle for quite long time, like an hour or so, to let the seals settle. And not too much grease.

And remember to change the oil line to the g-lader every now and then, as they disintegrate frominside, while looking good on the outside, making sure oil feed to your precious g-lader is fine!

 

Be carefull on using a smaller Wheel for the g-lader, as it can spin so fast, that it vibrates to pieces.

Speak for example to Tim at roettele racing in Germany about it. He also makes bigger g-laders, like the G65 and G75.

Front mounted intercooler and remap is always good,. and now adays some Guys are making an even better one than the Rallye.

Depending on tuning grade, you may want to run a colder spark plug.

If you delete the boost return, be sure that there is a bit of oil mist in the charger still.

Never use a k&n or alike, as it grinds Down your charger like very thin paste. I've seen the insides of what it does. Or change tour charger more often.

If carefully made, the g-lader will hold up. Service it completely and with better bearings, every 50.000 km, and you'll be a happy driver.

Keep the feeler on the inlet tubing clean and the oilmist (just a tiny bit) clean from the charger up.

The reason some people get much better power with the front mounted intercooler is not only it's bigger and may flow better, but also that some original coolers (the small one in the corner on the Corrado g60), is leaking.

I have changed the tightening bands to better type all over, so there is no leak.

Finally, the chargers came in 3 different versions, increasing power, as vw got some critique originally on the cars being slow. Which they are not.

I've knocked some 944 and a few 308 gtb's and many more in my Corrado G60.

Make a short shift. I did, and it's really better to drive. Increase your oil cooling, and delete the Little oilcooler with Water around, and go for a real oilcooler. The Corrado can run quite hot in oil. I change my full synt castrol oil every 5000 km always. Only original oil filter to be sure that flow through it is like it should be. No alternative filters here, thanks. I've seen a filter that did not flow the same as an original filter, and the guy lost his engine. Only give some pedal, after oil is 90 degrees.

Finally, I will say, always roll the car, and do it the same place. It's often seen that some bolt on mods, or even a flowing of a head, is making Things worse, or just the same. Every time you do something, roll it. It's the many Little Things adjusted completely, that makes good power. Not justa catalogue on stuff. Often items are boasted to be so and so efficient, but often with out real evidence. A testbench is easy to "pursuade" to give better results, than it actually do.

Air and airspeed and the perfect temp on the air is the way to go. Fuel alone is just wasted. To use it, you must have better flow and more air. I'm sure you know that, just mentioning ;)

On my Esprit turbo se, there are a lot of chips to be bought, and they are mostly marketing stuff.. No real power gains. Instead a lot of wasted fuel and eventually burnt piston Crowns etc.

Lighten your car for all the crap that sometimes sneaks in, like heavy stereo, heavy Wheels and so on = free power.

 

Just my two p as others may see Things differently.

Redfox.

Edited July 15, 2014 by Redfox

[Matt@OCD 0]

You will get good gains on a standard pulley with a tuned setup.

 

And you are right to an extent with the small pulley theory but the small pulley is used to build more pressure at lower revs, ie WOT from 2000rpm, more boost will be created at this rpm all the way to 6500rpm than with a standard pulley.

 

This is the means for the smaller pulley.

 

The boost return is so the boost system is open as it has to be but this is also aids in some more mpg as the engine is essentially ran as an N/A until WOT :)

[G_Power 10]

@ Redfox, some really good info there thanks.

 

@ Matt, You've hit the nail on the head!

The boost return is so the boost system is open as it has to be but this is also aids in some more mpg as the engine is essentially ran as an N/A until WOT

the car is essentially setup as N/A until WOT! I am quite happy to sacrifice some fuel economy to get more progressive power. (getting too old to drive around with my foot flat all the time :( ) Have you ever adjusted the boost valve? Do you think this is acheivable?

[Matt@OCD 0]

I haven't, I know people who have, so the boost return shuts earlier.

 

But it's a lot of faf and can quite easily make it a nightmare to drive!

 

And unless you're throwing the ISV away there's no need as that'll just bleed any pressure over 1bar

[G_Power 10]

that was my concern. Oh well I guess it's back to smaller pulley and a remap. The way that VW have designed the G60 is baffling, a supercharger that essentially acts like a turbo :scratch: maybe it was cutting edge 20 odd years ago but now just seems well err... eccentric to say the least!

 

Matt I'm overseas would you recommend an off the shelf chip e.g. SNS (not sure what OCD offer) or a piggyback mapped on the rolling road (done locally obviously)?

 

Any advantages/disadvantages (apart from the obvious)

[Matt@OCD 0]

It's just down to VW always strive to get power from small engines, while still giving good drivability and economy. Just what they're about really.

 

The 1.4TSI set up is similar affair, with a supercharger the engine can turn on and off as it pleases :)

 

off the shelf are fine, with a slight tweak of the sensor's you should have no issues at all.

 

A RR map is obviously better, as long as you've got a mapper who knows G60's and the digifant management, that's the only issue nowadays :)

[G_Power 10]

My local tuner knows digifant but not G60's. Anything specific he must be aware of?