G60 power delivery question

[okcid 10]

Hi guys,

 

Ok I have a mk2 golf with a G60 conversion.

 

I had it on the road for a while but the charger went over Christmas so is now laid up awaiting a new charger.

 

Sorry to the point......

 

My G would always pull well, really well, through the gears but when it hit about 5-5.2k rpm it would take off again like it's gone mad.

 

Same sort of kick as a vvtli or vtec when the other cam joins in.

 

Now it's a little annoying as I never take my car to the limiter and when you change gear there is a second or two before you hit the extra power again so drivability is not optimal.

 

Now the cars quick so it's not like it's running poorly up until the extra power.

 

Anyone else have this or know why it is doing it?

 

My set up is as follows.

 

Jabba Stage 4 charger

Jabba stage 4 chip

68mm pully

Mild head work,

Full powerflow system

K&N cone filter,

Boost return mod

 

I'm unsure of the internal work but TSR did my head gasket and advised it appears to have had some mild head work.

 

All help appreciated in advance,

 

Thanks

 

Adam

[okcid 10]

Just read this and feel I didn't address the point very well :)

 

Why do I get this extra surge up the top of the rev range?

Does the jabba stage 4 chip adjust the fueling at the top to give the extra kick and do any of you guys get this in yours?

 

It's very noticeable and not a slight kick, you hear the engine really perk up at this point. :s

[mimjed 0]

mine does a fairly similar thing, but doesnt go mental. ive put it down to the charger putting out max boost/full cam and full fuel. i have no cams in mine, but you may find you have in yours.

 

8v normally rev well as they arent so great on bottom end.

[Yandards 0]

If you are getting a kick then your map is no good (unless you want a kick that is)

 

A good map should ensure a nice smooth torque profile, I know when Crazy Dave of DG was doing mine I was getting a noticable kick around 4.5k and upwards, some tweak to fuelling ensured that I get no noticable kick now and the car is more responsive as a result of this. The MFA is also now pretty accurate which to me indicates that the injector pulse duration (which the ECU provides to the MFA) is now accurate for the quantity consumed and not being adjusted by the other sensors as much (lambda etc) this means the map in the ECU is good in my book.

 

There are other factors with a G60 that you need to be aware of, first of all the standard MAP will open the ISV up to boost return at around 5.2k up to the redline of 6.2k to ensure a smooth arrive to the hard cut rev limit, this is done to protect the supercharger from shock loading which can destroy them (same reason you never want to fit a toothed belt conversion). The ECU will also dump boost if it detects knocking as well as pull the timing back - the quality of the fuel you are using will have an effect on the knock of the engine and you will be suprised at just how much a modern engine knocks - the optimal point is one just prior to knock so all modern ECUs will advance the timing to a knocking condition and then pull it back slightly. This process will also have an impact on how the car feels under WOT (wide open throttle).

 

So if you have a boost return deletion or a re-route back into the 'supply' side of the boost system this will cause a kick as it messes with the fueling for a bit, but ultimately there should be no kick at all you should just get a constant hard pull - oh er!

 

The other factor with the amount of mods you have, especially when you factor in the age and variable condition of the charger and engine, is that an 'off the shelf' map is likely to be way off in terms of fuelling when you go open loop (ie WOT and off the lambda probe). Try some acceleration runs on part throttle and see if it feels faster than full throttle - if it does you need some mapping doing.

[okcid 10]

Dude your a technical genius :)

 

My mfa has always been well out. Mpg normally averages between 13-15 with a reserved right foot. Now it's not the best on fuel but think that's a little off, lol!

 

I'm doing a fair bit of things before it's back on the road terrorising scooby and evo drivers!

 

New charger,

Changing all coolant pipes

New boost pipes

Various sensors, knock, wts, lambda etc...

Filter, plugs, dizzy, rotor, ht leads,

Brakes

All fluids

 

Gonna be pretty busy but want to finish it off with a live map from DG as I'm hearing good things from forum members on here.

 

In regards to the boost return mod, is there any advantage to me having this apart from the noise value.

 

I know some argue it vents hot bad air back into the charger but also that it helps keen the charger lubricated?

[mimjed 0]

^expalins a good amount. its common with g's though.

 

on the plus side for you been offered a garage today, so my charger is coming your way shortly :(

 

going to miss the old ****wagon.

[okcid 10]

whoop whoop :) let me know mimjed :)

 

oh and has anyone used one of these?

 

http://cgi.ebay.co.uk/VW-Golf-Corrado-G60-1-5-bar-Pressure-Sensor-/290545227745?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item43a5d857e1#ht_534wt_1139

 

Any experiences with these?

 

Also Yandards you mention the hard cut rev limit.....now......

 

I have hit the limiter in 1st gear before off the lights and it did not bounce as i expected it to. When it hit the limiter the revs very harshly shot back down as if it had died but when i put foot on clutch it did not cut out....put it in second and floored it and it carried on as if nothing was wrong.

 

Any idea why my car has such a dramatic reaction to hitting the limiter?

 

I have only every made this mistake the once (on that occasion) and have been extremely careful since.

 

I hear that hitting the limited is dangerous for the G60 charger, as i have a jabba chip could this be a kind of safety mechanism. A mate of mine used to have a pretty serious G40 and that was treated with far less respect than mine and it was happy on the limiter, popping and spitting (actually sounded pretty cool, lol) all day at various track days.

 

Thanks

 

Adam