I know there have been a few posts about this topic in the past but it seems like a lot more guys are running the 9 lbs pulleys now.

My question:

What are the pulley sizes you are running and how much psi are you making?

In stock form, (the 7 lbs kit) my front left pulley was 38 and the front right pulley was 27. With the TS reflash I was able to hit 8.2 psi with this set up.

Recently ATI sent me out a 39 and 26 pulley which was supposed to up the boost 2 psi from stock. For whatever reason, I am hitting the exact same boost (8.2) psi with these new pulleys. Maybe I'm wrong but I thought when you increase the number of teeth on the left side (pulley 1) and decrease the number of teeth on the right side (pulley 2), more boost should be made?

What could be wrong and what are the pulley sizes you are running?

 

Here is what I was looking at:

https://my350z.com/forum/showthread....990&perpage=20

But you posted on that one back in the day . . .

 

Just when you think you understand something... (referring to myself)

Daking posted in that thread that his 9lb set consisted of a 40 and 25= 65. That is 2 higher than the stock 7lbs kit on the left and 2 lower on the right. The 39 and 26 which ATI sent us is 1 higher (left) and 1 lower (right), still equalling 65. If my theory (posted above) is correct, than daking should make more than 9 psi) However, he didn't have the TS ECU flash so he only hit 8.5 to 9 psi. Had he increased his rev limiter via the ecu flash he would have seen 11 psi like max did back in the day. This would also mean that I should have hit closer to 10 psi at 7.2 rpms. I give up.

Hopefully Eric will call you guys soon. One thing I know for sure is that you want to try and keep the 65 total teeth count, just so the belt fits perfectly. Other than that I am only speculating based on how I understand the ATI manual.

 

whosdaddy.....did you happen to change any thing with the exhaust ? Open it up more ? I could only hit 7.2 lb's with my vortech .Tuner said it may be that my exhuast was wide open and wouldnt allow full boost to build up , but would produce just as much power as if it did . Said he has seen this happen many times with F/I

 

Basically, Whosdaddy was making more boost with the stock kit pullies than with the new ones ATI sent.

Power was good . . .but psi could go up. If the psi was what we were thinking (10 psi @ 7000 RPM +) it would have hit what was originally desired.

Let me tell you as a N/A fan . . . man do the F/I cars haul. I will be keeping my eyes open for some deals .

 

OK, I have heard back from a couple guys I PM'ed/emailed earlier about this situation. Both say boost leaks...

Max said to check the hoses by the IC . He lost 3 lbs himself from a boost leak in that area. Another area to check is near the T/B.

It makes me feel a little better I guess. They both confirmed that with these pulley sizes I should produce 10 PSI at 7K.

 

What guages do you have Scott?

The leak I had Tadishi found, it's very hard to see.

I never liked messing with the larger pulley, The kit seems to like the 38 there for whatever reason. Make your boost with the smaller pulley and higher rpm's.

Oh and don't let the Dyno be the baseline for your power too many variables.

Also consider heat. It's smoking here.

When I made that post it was cool, now that it is 100 degrees my car is getting less dense hotter air.

Good luck man and be happy knowing that your car could not be in better hands. If I lived in TN Crawford would have to throw me out of their shop lol, I would live there (course I would bring beer!)

Keep us posted this boost level is really hit and miss it took me weeks of stressful calls to Eric and 3 sets of pulleys with about 10 flashes and two trips to TS to achieve what I did.

And on that link posted, true to my word I did add a bigger fuel pump and also the Edge Verter so our cars are so similar it's scary. What is your exhaust setup I forgot?

Crawford plenum and cats but what about headers and catback?

Thanks!

 

I tried to get a hold of Eric today to confirm the right pulley combination. He was to call Doug and then myself if he had time. I'm hoping he spoke with Doug earlier today.

Concerning Crawford, I am extremely confident in Doug and the Crawford crew. They couldn't be any better and they know this car better than anyone. If I lived 10 hours away it would be worth the drive just to have them work on my car...

As far as the horsepower, it made great numbers for 8psi on a 5AT. That really isn't a concern. I am concerned about the boost issue. Until someone confirms these pulleys are the correct sizes to make 9-10 psi, then we can't rule out wrong pulley sizes. From what others have said and from what I have read, they sound correct. The only other potential issues are belt slipping and leaks which Doug is confident we don't have. (I'm hoping Eric can shed some light on other potential issues)

As far as other mods: I have the stillen exhaust, crawford plenum and crawford headers. (Max you should see these headers. If you didn't already have some installed I would try to get you to install these. They are very agressive looking.)

If these are the right pulleys then the car needs to go back to the dyno to make sure the A/F ratios are OK. AT 8.2 psi the highest it got was 12.8. At 10 psi I am not 100% positve the A/F will hold? In which case the flash and fuel system need to be evaluated.

Again, anyone making 9lbs with the ATI kit please post your pulley sizes...

 

I would agree with you there. At 9 PSI I was 12.2 at the highest point *before* adding the larger fuel pump.

Yeah I saw Doug's headers, pretty sweet.