Nick_04k

So im running A&A bracket with a Novi 1500 and 3.25 upper pulley with stock dia ATI lower. Car is stock A6 with headers being the only non supporting mod.

Im only making 9.5psi with no restrictor plate in. Belt is definitely tight, but the manual tensioner is not maxed out (not using 100% of available belt wrap) Im running a brand new GATES K060900.

I have pressure tested by hooking a compressor to the blower inlet @25psi line pressure and using a squirt bottle. Found and fixed several very small leaks, MAF card, vac block, BOV nipple, etc. System now shows no leaks at all.

My logs always show my kPA building linear, and never dropping under WOT. Has anyone seen belt slip this consistent before? I was under the impression it usually is seen as boost building then falling off slightly, or maybe varying one pull to the next. Mine is just dead consistently low maxing @ only 167kPA around 6700rpm. Im stumped

Patriot Six

I made 11.5 psi with a 3.4 pulley on a Ti trim. With the same size balancer, but switching to 8 rib, new A&A secondary drive and a slightly larger 3.47 pulley, I made 13.5psi.

With the original set up, I couldn't detect any belt slip on the boost curve, but obviously the secondary drive is a lot more efficient and has more belt wrap and belt contact with the 8 rib.

Nick_04k

Pretty much answers it. Idk what to do. I really dont want to put insane belt tension on or convert to DD, or use carbonite..?

I suppose ill try adding more tension with the belt warm
Pray for my accessory bearings lol.

Patriot Six

As the belt stretches, you'll have to constantly adjust the tension, which will put a lot of sideload on the accessories. I avoided that with the secondary drive and gained 2 pounds of boost.

Unreal

If manual tensioner is maxed, you have too long of a belt and need to get a shorter one.

Nick_04k

I got a little more tension on it and peak boost came up to 10.2 @6600
still way low!

Anybody seen a big diff running the RPM belt?
Any other suggestions on what could be going on?
Anybody ever found a need to change bypass valve spring or anything like that?

Patriot Six

I think you're seeing the limits of a six rib. I would say go 8 rib and/or secondary drive. Boost is one thing, but have you made your power goal? If so, and you're not able to see boost loss up top, leave it alone.

Nick_04k

I dont necessarily have a power goal but i intended to lean on the car a bit for sure so 650-700ish i guess. I dont think ill even be 650 on 10psi and e85?
Its not slow by any means so if this is all i can get with the hardware i have thats fine, ill deal with it for awhile.

Most important thing to me is that im not overlooking something that is going to cause a bigger issue over time.

Patriot Six

650 with 10psi and e85 should be possible. The key is having enough octane and the proper tune. If you're content with how it drives, it should be fine, but you have to check belt tension as the belt stretches.

You can always do a secondary drive later on, but I can almost guarantee you'll pick up boost and lighten the load on your accessory pullies, if you go that route.

southspeed

I was reading schpenxels thread yesterday and noticed he switched to the 895 belt early on after using the 900. maybe that will help.

russ472

Not building a ton of boost isn't really a bad thing if the belt isn't slipping and its making power. I can build 14lbs of boost with the 3.25 pulley and no restrictor at 6800 rpm with a napa 6 rib belt. I think that is a ballpark norm for that setup with a stock cam/ headers setup.

Perhaps your exhaust is flowing a ton of air and you have little back pressure?

Nick_04k

Thats what everyone ive talked to says really. ECS/A&A are both saying 6rib and Novi/Ti trim should do 13 to 15psi with 3.25 pulley and be capable of ~700whp and 140+ trap speeds.

I also think my exhaust is basically what everyone else at this level has too, just a basic
1 7/8 header through an NPP.
I dont think people with stock manifolds usually opt to remove restrictor and/or go 3.25 pulley.

russ472

i guess there could be a possibility your blow off valve is leaking boost or your intercooler could have had a slight leak if a small rock hit it.

SBCGENII

Did you check the intake manifold for leaks?

C U IN REARVEIW

how much work is involved to do the secondary drive......im about to pulley way down from current

Patriot Six

Need to have the latest generation A&A bracket, install a new balancer, jackshaft pulley, and then you need to add a tensioner for the alt belt. Definitely worth it if you plan to max out your blower.

C U IN REARVEIW

I have an A&A ti-trim and going from a 4.0" to a 3.4" upper pulley

Patriot Six

I've got a Ti trim with 8 rib 3.47 blower pulley and stock size balancer. 3.4 was having belt slip with 6 rib and previous generation bracket. No more adjusting the tensioner and I picked up 2 pounds of boost.

C U IN REARVEIW

ls2? What kinda power it make? Just 8 rib,no secondary drive?

Nick_04k

Honestly never checked the intake manifold. Is that common? I never had any vacuum leak NA to my knowledge so i guess i assumed no boost leak through IM either.
Should check it i guess.

I already have a new ATI balancer and DO NOT want to remove it to do a DD lol.