Talking to a rep at vortech, he advised against using the 3.12 pulley. He told me to tune the r4 fuel and timing on the 3.33 instead. He said that i would be better off adding 1 degree back in than changing the pulley. Im only using 93 canadian octane gas which i have heard is better than 93 american gas( dont know why but i will parallel it with our canadian beer ) Any thoughts on this. What he said kind of makes sense as they tune to 91 octane on their kits.

 

If I remember right the stock timing map for the Vortech is...2...4...6...10 degree's starting at 4000 or 4500rpm . You can go with the 3.12 and reduce the timing . But you should have a good tuner do it . Each car is different and the tuner would know how much is safe

 

Based on my recent experience, I think you're better off with the 3.12" pulley. As booger says, it will take a little more time to tune properly, however...

with the smaller pulley you can make the same power you do by pulling the extra timing. The difference is, the more timing you pull, the closer you are getting to detonation. So, the power made using the smaller pulley should be safer.

Now, if you put on the 3.12" AND you pull the same timing as you would with the 3.33" pulley, then you would make more power, but you are running the same risk (or more) as you do with thet 3.33".

Make sense?

for reference, my peak numbers with a very aggresive tune and the 3.33" pulley were 425rwhp and 337rwtq. My peak numbers with a safer tune and the 3.12" pulley are 421rwhp and 340rwtq. Pretty comparable, though with the 3.12" pulley I have more "area under the curve" since boost comes up earlier in the powerband

 

yeah makes sense, ive got the 3.12 on order

 

What belt size did you use for the 3.12" pulley?

 

its the gates xxxxx930 i beleive.

 

Are you getting knock?

If so be CAREFUL. If not you should be ok. But do scan for knock if you want to keep your block.

You can probably get away with it if you have the supporting mods i.e. headers, downpipe, colder spark plugs, hood vents, race gas.

 

So when i get the 3.12 should i tune a/f only, as the stock r4 pulls quite a bit i timing to start with? 6 degrees at 6500 to be exact. Once you get up to 10 psi it pulls 8 degrees.

Another qustion, is it better to tune via rpm or boost. I see vortech goes the rpm route.

 

Reps are always back pedalling. Told me that system was close to max . So I asked why on your website do your specifications show more than kit provides. Got the well you have to account for pressure loss throught the system. Replied so you are telling me that there is like a 12psi loss throught the system. Thats when they gave me the goods