I’m to install my Vortech and bough the same ATI, 6.8” crank pulley. Did you bought this when you have the Vortech?
How much larger the belts should be from stock 5.75” ?
I’ll take out my UR crank and leave the other 2 pulleys. Charger pulley is 3.33”

 

no, i only put the ATI on after I changed my setup and sold the vortech. Like I said, that crank pulley will add 1000 rpms onto your impeller speed off the bat. wayy too much unless you were only using the 3.33

I dont have a standard belt routing anymore either, so no idea on belt length you need. best bet is to measure with some string and buy 4 or 5 belts around and keep the one that fits the best.

Thats what I did

 

I re-did the measurement on my newly acquired Fluidampr to compare it to the same 5.75 measurement point on the stock pulley (which is where it mounts the belts) and I measured 6.125, the same as you got from Fluidampr...I'm not sure why they told me 6.25 when I called them

 

Ok, so after a good deal of searching/research, all "off-the-shelf" dampened crank pulleys (ATI,Fluidampr) for the VQ are slightly OD (6.610", 6.12"). The only one I found that is stated to be of stock diameter size are Ross Metal Jacket (made out of AU).

These are more expensive than the ATI or the Fluidampr, and have not heard of one being installed on a VQ35:

http://rossperformanceparts.com/meta...balancers.html

I was willing to try it out, although none are available presently, and won't be for another month or so.

The problem with OD damper pulleys on a SC setup, is the potential for overspinning the blower and/or throwing it out of its efficiency range.

So is the OEM crank pulley safe on a SC setup on stock block, given the extra load/strain being placed on the crank/bearings due to the SC? Is a dampened pulley really only needed/recommended for a built engine?

If I can't get the Ross unit in time for my tune, my options are either to:

1. Replace the GTM 85mm SC pulley for the HKS 95mm SC pulley and leave the OD ATI crank damper on--this would make the impeller speed 116,838 rpm at 7k.

2. Replace the OD ATI damper with a new OEM crank pulley and leave the GTM 85mm SC pulley on. This would make the impeller speed 113,506 rpm at 7k.

3. Replace the OD ATI damper with a slightly less OD Fluidamper, and replace the GTM 85mm SC pulley for the HKS 95mm SC pulley. This would make the impeller speed 108,265 at 7k rpms.

I was leaning towards option 1, but was concerned over using the OEM pulley with a 400/400 SC setup.. But others are putting down more power with SC and are using the OEM pulley without issue?

I'd like to prolong stock engine life, but if an aftermarket dampened crank pulley isnt really necessary for 400/400 SC, I'd keep the extra few hundered in just using the OEM pulley.

My concern with option 2 is that I am still overspinning the blower by ~6800 rpms at 7k, although this is better than ~20,000 over max limit with current ATI crank pulley and HKS 85mm SC pulley, and I would have a dampened pulley on the crank.

Also, I'm not sure what would effect my boost/power curve more--changing the SC pulley or the crank pulley? Could changing the SC pulley back to larger size negatively effect power more than the crank pulley, since it is closer to the blower?

Option 3 would keep a dampened crank pulley (Fluidampr), but with the larger SC pulley. This keeps the SC impeller speed well within the max limits, but may not be agressive enough and I may lose more power than I want?

thoughts/suggestions?

 

FYI,
I have now cracked 2 stock Harmonic Balancers. I highly recommend anyone going FI (well especially built motor), going with a fluid dampener!!!

Tom

 

What are you power levels and what rpm are you revving to?

 

Pump gas (14-17psi) 530-590rwhp
Race gas (25-30psi) 650-769rwhp

Stock valvetrain was reving to 6700rpm on street, would see 7200rpm on dyno and when needed.

Going to fluid dampener.

Tom

 

Thanks for the info. Do you launch a lot? It would seem that at those power levels on a built block, a harmonic crank pulley/damper would be highly recommened if not a necessity.

However, at 400/400 power levels on a stock block, with stock redline, it would seem that the OEM crank pulley might be just fine. Of course, it couldn't hurt to have one on, however. I'm just not sure of the need/true benefits with a stock motor at 400 power levels.

I would rather have a dampened pulley to be safe, but since I am SC and the only readily available options are OD, it's more difficult to have one on and still not overspin my blower.

The Ross damper, which is stock diameter, I am being told weighs about 3 lbs. heavier than stock. This is because it is made out of steel and actually has 2 dampers in 1 (vicious fluid damper inside an outer shell, containing rubber elastometers)--so it seems to be a hybrid between the Fluidampr and the ATI. 3 lbs. heavier than oem seems much heavier and I'm not sure how much extra strain this would put on the rotating assembly though.

So it's either I swap out the ATI pulley for a new OEM one or leave the ATI in place and change the 85mm SC pulley to the 95mm pulley...Still deciding on which route to go...

 

If the ATI/95mm combo puts u in the right psi and max rotational speed I would do that as this would be the cheapest way to go. You already have the parts. If not sell your ATI and buy the ross one.

 

If changing the SC pulley, it will start to be over stated limit @ 6600 rpm (110,161)
@ 6700 rpm (111,831)
@ 6800 rpm (113,500)
@ 6900 rpm (115,169)
@ 7000 rpm (116,838)

If changing crank pulley it will start to be over stated limit @ 6800 rpm (110,263)
@ 6900 rpm (111,884)
@ 7000 rpm (113,506)

So changing the SC pulley will not bring down the impeller speed as much as changing the crank pulley. However, I'm not sure which option would result in maintaining the most power (e.g.still trying to find which option will maintain the most power/boost, or if it doesn't matter). Both have an effect on impeller speed, but since the SC pulley is closer to the blower, does it have a greater affect on boost than the crank pulley?

As far as the Ross unit, it being 3 lbs heavier and $550, aren't great, although it does keep stock diameter. More importantly, it likely won't be available in time for my scheduled dyno appt. at the end May.

 

So I ended up swapping in a new oem crank pulley, and am somewhat regretting that decision. While, impeller speeds are in check and the power is more linear with the blower being more in its efficiency range, I lost 4 psi and about 50whp/50trq.! I can really feel the decrease in power

So, I am thinking I will swap crank pulleys again (either back to the ATI or a Fluidampr). I hate to keep spending more money, but I am leaning towards the Fluidampr because its OD is in b/w stock size and ATI, so it would offer a good balance between gaining back some lost boost/power and not as much overspinning as the ATI (it would start to overspin at 6400rpms and about 10% overspun at 7000, as opposed to the ATI starting to overspin at 5900 rpms and about 18% overspun at 7000). The Fluidampr does weigh about .5 lbs more than the ATI, however.

I also have read some internet comments by domestic guys claiming the Fluidampr ruined their crank/engine and will only use ATI. I'm not sure if this is install error/hearsay/or actual fact. Internet comments are internet comments. The Fluidampr "meets Sfi spec" while the ATI is "SFI approved"--I'm not sure how much this matters for street application--some state Fluidampr is not allowed in some racing sanction bodies--I dunno. I haven't heard of any negative Z/G accounts with the Fluidampr, though. It seems both the ATI and Fluidampr get good reviews.

So although I don't want to spend extra money on a crank pulley, the Fluidampr might be my choice simply because it is in b/w the OD size of the ATI and stock crank pulley. But I haven't fully decided yet and will probably have some time to choose before install/retune. The extra weight, internet comments, and purchase costs, are leaving some doubts in my mind, but the ATI calculations seem a little to high for me and I'm not happy with the power levels with the stock crank pulley.

I was also thinking of getting a Motordyne ART pipe/XYZ with HFC to replace my PE HFC's/Tanabe y-pipe to get more power and or methanol/alcohol injection, but would like to sort out the crank pulley issue first and the MD products are not to be in stock for at least a month.

Any comments/suggestions?

 

Can you share what issue you have seen with the Fluidampr?

The ATI may just be too big for my application...So i'm leaning towards the Fluidampr.

 

str8dum, are there any negative effects of greatly underdriving the AC with the ATI crank? (e.g. AC compressor overworked, AC not functioning 100%)?

 

ATI only makes one type with a/c provision

Having had it on my car since August 2007 the a/c works just fine

 

^^thx. for the info, are there any benefits of greatly underdriving the AC?

 

Can you guys confirm that the AC side of the Fluidampr is stock size and thus uses stock size AC belt? And the Alternator side is about .38" larger than stock--so is a slightly longer alternator belt required with the Fluidampr or is a stock sized belt used as well?

Can anyone provide a lenth of the belt they are using for the alternator side and/or the part number/brand?

thanks.

 

Just search on various sites for the benefits of underdriving, and you can weigh it out for yourself. In my case, given the rpm's my engine turns, the more it's underdriven, the better. That, and it's steel sleeve, are why I went with it.

Given your setup, your best option is clearly the stock pulley IMHO, or having something custom made, as none of these pullies are designed with a belt driven S/C in mind

 

To those that are using the ATI:

What size/number/brand are you using for the AC and alternator?

I think stock is 4pk945 (AC) 6pk1180 (alternator)

I would like to use Bando, but need the correct sizes before I order.

edit: The HKS SC I am using has a different idler pulley, so the alternator belt size may not benefit me, but the AC size would.

Thanks!

 

I’m in the process of installing my vortech kit and ATI .
Found no info on this site but saw a picture on one of the vendor’s site with the pulleys and the Bando number showed in that picture was;

4PK990
6PK1220

Not sure if these are correct.

That’s 1.7”-1.8” longer, my Vortech came with Gates K060795.
4PK990 = Gates K040390

So I ordered and received K040390 and K060815, but have not been able to install yet.

 

the belt that injected sent me with my ATI pulley wouldn't fit for my a/c. Two of us tried with a pry bar and couldn't get it to go on. I had to go up to the next size and with the tensioner all the way down it was just barely tight enough. So it's between sizes. Really weird.

I wish i went with fluidampr.