l67 intercooler

[Kyle H]

hey guys ive been wanting to upgrade to a smaller pulley on my l67 and wanting to know if running 11 psi with out intercooling it is okay?

mods list:
pacemaker extractors
2.5 in twin catback exhaust
200 cell high flow cats
mace cai
shaved heads
yella terra rockers (unsure of ratio)
yella terra 87mm (10psi) pulley and snout

 

[Phillbert]

Have a look through @peteinoz thread about his L67 VS Ute

VS L67 Ute Project

So I just bought a very tidy 98 VS L67 ute As it turns out my 17 year old daughter is extremely keen to go drag racing.. Bonus!! I did my time as an apprentice mechanic and did 2 years after that, but haven't really touched the spanners much since then, erhm 3 decades ago. So this will be...

forums.justcommodores.com.au

He is running a smaller pulley with no intercooler interesting thread...

I would add to your list a lower temp thermostat from MACE.
In general rule you don't want to go smaller than 12 psi without an intercooler due to heat buildup.

 

[losh1971]

E85.

 

[Kyle H]

Have a look through @peteinoz thread about his L67 VS Ute

http://[URL]https://forums.justcommodores.com.au/threads/vs-l67-ute-project.285894/

[/URL]
He is running a smaller pulley with no intercooler interesting thread...

I would add to your list a lower temp thermostat from MACE.
In general rule you don't want to go smaller than 12 psi without an intercooler due to heat buildup.

definitely not going smaller than 12 psi without intercooling it, just wanting to make more power even if its not huge difference from 10 psi. thank you for the help mate

 

[Kyle H]

E85.

looked into running e85 before but not into it

 

[Phillbert]

definitely not going smaller than 12 psi without intercooling it, just wanting to make more power even if its not huge difference from 10 psi. thank you for the help mate

With your list above i would just get a bigger Throttle Body and a decent Tune. I think it would make a big difference without breaking the bank too much.

 

[shane_3800]

Honestly I would be trying to knock the boost down with engine efficiency from here if you're looking for more power.
I would be getting bigger intake valves and a bowl job with a proper Newen CNC seat job. Higgins heads in Melbourne can do the valve work or Rams head porting in Sydney.
Next step would be a cam and move to a stock ratio rocker still from Yella Terra unless yours are stock.

You might drop from 10psi to 8psi and pick up 10% horse power as the blower isn't worked as hard even though it's spinning faster as it's not compressing the air as much so less intake heat.
Those are very conservative figures btw.

Now you can add a smaller pulley and be under 10psi.

 

[losh1971]

Can the L67 take bigger valves? The early V6 couldn't as I looked into it.

 

[shane_3800]

Can the L67 take bigger valves? The early V6 couldn't as I looked into it.

It depends on certain factors. If the exhaust is too close to the intake you have to shrink the exhaust and sink it down into the seat.
Lots of machine shops will just do two bigger vlaves this is why you shouldn't let machine shops touch your heads and use a head porting specialist.
Also if you sink the exhaust vlave you should sink the intake then do some chamber work to smooth the chambers back out. So no it's not just a cut'em bigger and done job it takes a little knowledge and skill to do.
You usually only ever need to increase intake valve size as most heads have too much exhaust valve anyway.
Also sinking the valves will lower compression which isn't such a bad thing really on a forced induction engine which already has shaved heads.

 

[Immortality]

Ecotec/L67 can take marginally bigger valves but the difference isn't much. The last of the ecotec/L67's in the US got slightly larger valves from the factory. See

ZZP Stainless Valves

ZZP factory length Stainless Valves. These swirl polished valves are sold in sets of 6. Choose between Intake or Exhaust models. Intake sizes are 1.80" or 1.84". Exhaust sizes are 1.60".

zzperformance.com

Machine shops do as you ask as their job isn't specifically to increase performance. Having said that, the machine shop that did my ecotec heads did a 3 angle valve job to blended the seat into the port and because he had to take a bit off the exhaust seats to clean them up he also swept out the chamber to make sure the valves weren't shrouded.

Ideally those heads only need a little hand blending into the port and cleanup of the short turn radius.

And with the valves fitted where you can see the extra material removed to unshroud the valves in the chambers

I like him enough to take a set of 304 heads there next and let him work his magic on them.

The other issue with going much smaller than a 3.4" pulley is that you exceed the resolution of the standard MAF. I run a 3.2" pulley and 5% OD balancer and have maxed out the stock MAF just over 5000RPM. Honestly, anything smaller than 3.4" and heat management becomes critical as intake temps rise quickly.