65mm pulley versus 68mm pulley....................

[DORSET_V_DUBSTER 0]

What are the pros and cons on running the two different pulleys. What I can gather is that a 65mm pulley will produce more boost but cause premature wear on the charger, is this correct? :?

 

Opinions please!

 

Scotty :D

[bazgreener 0]

You also need to restrict your max rpm to 6k with a 65mm.

[G60 0]

no ya don't! i rev to 6300-6400...mine's gettin rebuilt in a couple weeks though. :D

[Dubcharged 0]

You can rev to 6300 with a 65mm, you have to restrict yourself to 6000rpm with a 62mm.

 

I'm using a 65 and love it! I make 15psi boost and thats with a 268 cam (there'd be more pressure build up without a higher lift cam).

 

When making 15psi and over you need to uprate the injectors to 30lb items and obviously have the corresponding map.

 

I can supply the injectors and we've mapped a host of chips for the 30lb injectors, one which i'm currently testing. :D

[DORSET_V_DUBSTER 0]

Right..........So if I fit a 65mm pulley and sns chip is it absolutely necessary to fit the 30lb injectors and have a re-map?

 

This is all confusing to the novice!

 

Scotty

[G60 0]

not absolutely... but if you're pushin mad air through your engine (like you would with a healthy charger, 65mm at 6000+rpm) you're going to lean out (not enough gas, too much air) and you'll melt your lump.

 

i'd say as long as you have a healthy fuel system, and you're not boosting much past 15psi, stock injectors are fine. if you get 15psi before you hit 6k.. then dont rev it any higher then whatever rpm makes 15psi until you get new injectors..

 

or you could get an air/fuel gauge to make sure...but they are not so accurate all the time.

 

or you could get an exhaust temp gauge.. thats a better idea. if you're lean, the temps will jack way up.

 

hope you're less confused! :lol:

[Dubcharged 0]

Basically you don't need 30lb injectors until you're making 15psi and over. :D

[LowG 0]

how much do 30lb injectors cost?i hope i make more than 15 psi with my new charger. Guys what about O2 sensor,im sure you have to uprate them aswell or im i wrong?

[Dubcharged 0]

Nope you dont need to touch the O2 sensor cos your gonna be making peak boost under WOT therefore the sensor is bypassed anyway.

 

I've pm'd you a quote on the injectors :D

[LowG 0]

oh i just asked you again about sensors..dope :D

[bazgreener 0]

According to this site you should restrict your max revs to 6k with a 65mm pulley. Even if you can rev to 6400 this is very close to the chargers design tolerances so would be safer to change at 6k.

IMHO :)

[Dubcharged 0]

Baz, when you select the pulley size the limit is shown by the red arrow and the limit figure that they display is just the closest lower 500rpm increment.

 

On a 65, the limit is near more than 6500 since thay say 13000rpm is the charger design limit and it reaches 12899 at 6500. So i just change at 6200 - 6300. I wouldn't go so far on an unported charger of course :shock:

[bazgreener 0]

ok :oops:

[G60 0]

yep.. right about 6300 i shift... 6400 if i'm really goin to town.

 

but all that changes now because the charger is off, and about to be rebuilt! http://corrado.atx-hosting.co.uk/viewtopic.php?p=12139

[G-Lader 0]

heard somewhere that the G-lader came in two diff. types - A 4 pot diffuser and another one,the 4 pot was stronger and can take smaller pulley's if the charger is in good condition.If its the other no. of pots then should stick to 68m pulley? Jabba list the type on the re-build paperwork (mines a 91 and a 4pot type)

May be talking rubbish though!?

[Dubcharged 0]

You're right, they did come in 2 variants, the other is a 6 pot which is weaker (apparently).

 

One of the big charger killers is heat (destroys the seals). The smaller the pulley the faster it spins therefore the more heat it generates. There are a couple of things that can be done to minimise heat:

 

Remove the bypass pipe and route a cold air feed to the filter.

External Oil cooler.

 

I've tried and tested 68's, 65's and 62's. My personal favourite is the 65 and thats what i'm currently using. :D

[G60GAZ 0]

if you remove the bypass pipe do you just block off the inlet on the chargeror wat?

Also the bleed valve on the throttle body is it safe to just vent this to atmosphere cus thats wat i have done and i also adjusted the linkage so the the bleed valve butterfly closes sooner which i heard can give beter instant throttle response cus you get full boost sooner?

am i talking sense here dubcharged or complete poo?

 

 

Edit: Swearing

[G60 0]

you can just block it off, but dubcharged's point is that you should rig up a second intake and bring some more cold air into the charger. thats what i'll be doing now that my charger is back from the rebuild.

 

it is safe to just vent to the atmosphere, but stick a crankcase breather filter on the blow off on the bottom of the throttle body so no crap gets in.

 

not sure about adjusting linkage so the butterfly closes sooner.... you should have it adjusted so it is just hitting the WOT switch when the pedal is in the floor... if you have it set too tight (which i think is what you're talking about) you'll stretch the cable and it will go down the shitter... its a part worth replacing anyway if you already have a stiff pedal... if you dont have a stiff pedal yet, you will soon with a cable setup too tight! :shock:

[Dubcharged 0]

If you remove the bypass, you can either block off the end of the charger with a blanking plate, or put a second filter on it.

 

At the throttle body end, you will see a 90 degree bend rubber hose which goes into the plastic bypass pipe. This can be turned away from facing the engine bay otherwise the constantly venting air will make a lot of noise as it hits tubes/wires/etc etc. I will be doing a step by step procedure for this on the SNS site once its finally done :(

 

As for adjusting the throttle linkages, you wont get more boost, but you will be feeding more of the available boost to the engine. There is a danger in doing this since you'll be feeding boost to an engine whose ECU is still in closed loop mode. Therefore your fuelling is still cycling between rich and lean yet your engine is being loaded with more boost than usual. :shock:

 

We're currently testing some code which wll ensure your ECU provides the engine with correct fuelling under boost with or without WOT switch activation.

[G-Lader 0]

just tested the boost using the MFA (got the de-coding of mfa no's on vwvortex thread,2nd page technical g60)anyway read 1870 at approx.6000rpm third gear,seems to be roughly 13 psi which i think is pretty reasonable for my mods? Anyway thought id share as its the first time i have seen the de-coding list for the mfa!