How much timing should I see with 79mm pulley?

[raycer]

Swapped from 85mm to 79mm pulley on my VMP Gen2R. With the 85 I was seeing -3 Knock for a total of 20.5 degrees at WOT. Now I am seeing +1-3 knock for a total of 14.5-17.5 degrees. Seems like a lost cause but somehow the car feels faster . Should I be seeing more timing ? Am I making more power or chasing my tail?
I will track test it to see if I improve, just looking for some opinions.

Sponsored

 

[yote41]

I see 17 degrees with 93 on 10 psi

 

[raycer]

This is what confuses me. From what I understand a lb of boost makes similar power to a degree of timing. So ..

If I'm seeing 20 degrees at 8 psi and 17 degrees at 10 psi am I really making more power at 10 psi?

 

[yote41]

Its a wash really. Lower timing and higher boost equals about same as higher timing and lower boost. Your motor will be hsppier long term with higher timing and lower boost if you have the octane.

 

[raycer]

79 mm is the smallest recommended pulley for 93 according to VMP . Lot's of guys running this with no issues.

 

[Jay-rod427]

the 79mm is still on E85? it shouldn't really drop much timing with small boost increase. But if you're now on 93 with more boost ya timing will drop quite a bit.

 

[raycer]

Unfortunately no E85 here.

 

[Jay-rod427]

Doh I just saw the 85mm pulley and my brain said E85. LOL. then ya adding boost to 93 will force it to drop timing as cylinder pressure and heat goes up.

 

[ahl395]

When your limited by octane you will exchange timing for boost and vise versa. As said it's basically a wash, both have their pros and cons and its generally best to run a good balance of the two.

This is what confuses me. From what I understand a lb of boost makes similar power to a degree of timing. So ..

If I'm seeing 20 degrees at 8 psi and 17 degrees at 10 psi am I really making more power at 10 psi?

Peak it will be around the same. But depending on boost curve vs. timing curve you may get power sooner.

 

[ckendri]

I've got a similar experience. I am on E70 with a 79mm pulley on a VMP Gen2r... 1st gear generally sees up to 22 degrees, but 2nd, 3rd, etc. do not seem to see more than 15 degrees. I will get with my tuner, but thought I'd make a quick post here for thoughts. I’m currently stuck at the revenue office, or I’d post the log. The other thing of note is there is no knock. Maybe this is normal, and I’ve never noticed this limit before. I am trying to get better about logging and reviewing, so any advice is helpful.

 

[ramirj2]

Unfortunately no E85 here.

Add VP Octanuim, Boostane or Torco to the tank when you need the power and you will get your timing back

 

[Tommy V]

What are your intake air temps as these go up as you go through gears.High iat will cause the ecu to pull timing.

 

[ckendri]

What are your intake air temps as these go up as you go through gears.High iat will cause the ecu to pull timing.

Yeah, they are around 105°-110° on IAT2. I didn't figure it would pull timing until 130°-135°.

 

[raycer]

What are your intake air temps as these go up as you go through gears.High iat will cause the ecu to pull timing.

Less than 120

 

[raycer]

Just had it at the track yesterday and ran 10.71 @ 130. So its making more power. 15 degrees timing.

Sponsored