Ok Powerdyne guys, why am I eating belts and detonating?

**00whiteGTvert** · 11-14-03, 05:06 AM

I spoke to Powerdyne about my BD11A.

I told them I wanted to do a 2.7" (11#) blower pulley and maybe even a 7" crank pulley on top of that for more boost.

They told me not to go any smaller than a 2.93" (9#) pulley and stick with the stock crank pulley.

They told me any more than 9# boost is overspinning the blower and would not be a good thing, now I see why.

Now I have to decide between a Vortech S-trim or a Novi 2000.

Good luck,
Howard

**mr.b** · 11-14-03, 06:38 AM

if you have the performer rpm heads they have 60cc chambers, correct? and what kinda pistons do you have? are they dished, 2 valve relief, 4 valve relief? how far down in the hole are your pistons? .010,.020,.030

i did a quick calculation for a 60cc chamber, 4 valve relief head at .015 in the hole and got 9.13 to 1 compression.

if your pistons are 2 valve relief it will make your compression higher. Basically need more info. on what you have.

As far as the powerdyne goes, i called them one day to get some specifics on their blower. I asked the "tech guy" what was the adiabatic efficiency of the blower, the speed that occured at, the pressure ratio for it, etc. he replied with "we dont have that kinda of information". How do you sell something and not know what it does? Anyway, i wasn't to impressed with powerdyne after that.

I believe it would be real easy to overspeed these blowers because I think they aren't very efficient, therefore heating up the air increasing your chances of detonation.

**Psychdaddy** · 11-14-03, 11:24 AM

Quote:

Originally Posted by mr.b

if you have the performer rpm heads they have 60cc chambers, correct? and what kinda pistons do you have? are they dished, 2 valve relief, 4 valve relief? how far down in the hole are your pistons? .010,.020,.030

i did a quick calculation for a 60cc chamber, 4 valve relief head at .015 in the hole and got 9.13 to 1 compression.

if your pistons are 2 valve relief it will make your compression higher. Basically need more info. on what you have.

The pistons are 4 valve relief and were pretty much flush with the hole. Might have been barely out of the hole .005 - .010. What calculation are you using?

**mr.b** · 11-14-03, 12:22 PM

dyno 2000. if your pistons are out of the hole then you are running at least 9.5 to 1 probably closer to 9.75

**mustangdaren** · 11-14-03, 03:15 PM

Eating belts has got to be bad for you. I usually only detonate when I eat beans.

**Psychdaddy** · 12:50 PM

**StangFlyer** · 08:14 PM

are you talking about this washer?

http://www.usawebcraft.com/images/PD7.jpg

If you are, THAT IS A WASHER regardless of what the company says.

My airplane machanic had a thin stainless steel washer that fit perfect.

Al

**Psychdaddy** · 12:51 PM

**StangFlyer** · 09:37 PM

If you look close, there is a slot in the shaft that the washer snaps into. It should be a tight fit over the shaft at the point of the slot. If you don't get it on fully, the washer slides around and trashes the belt in short order. (I know from experience)(you have to tap in on pretty good with a small socket)

I used the thin washer mentioned above and it worked fine for the remaining 5000 miles I had the blower. I'm pretty sure the guy I sold it to hasn't had any trouble either.

I wish I could remember the dimensions of the washer. We mic-ed it and found one in his parts bin.

Al

**mr.b** · 11-15-03, 07:28 AM

psychdaddy, just because your air to fuel ratio is 11.5 to 1 this doesn't mean you will not detonate . With 9.5 to 1 compression and 10 pounds of boost your effective compression ratio is 16 to 1. And you don't run an intercooler so you are making a lot of heat. With regular pump gas you are going to detonate. If the air to fuel ratio was the only thing that mattered why do they make race gas? Everybody would just tune for 11.5 to 1 air fuel and been fine, right?

go to this link and read, it is very informative

www.kuhlsuperchargers.com/tech%20p05.htm

**Psychdaddy** · 12:52 PM

L8 MUSL · 11-15-03, 04:49 PM

What I would add to this discussion is this:
I would get detonation with a relitivly low base timing of 11 degrees at full throttle when I allowed the computer to manage the timing advance. When I remove the SPOUT connector and run a base of 30 degrees and then pull out 1.5 degrees per lb. of boost I have no problem. I have 10 to 1 compression.
I also have been running the 11psi pulley for quite awhile without problems, but the info about the bearing is verey interesting because I'm sure I will need it someday.

dsmyth8604 · 11-15-03, 09:04 PM

My cousin has a powerdyne supercharger with less than 2,000 miles on it and it's still on warranty. He's selling it for $1500 or maybe a little less for me. The thing is he had a lot of problem with throwing belts all the time(not the internal belt). It's a 9 psi supercharger. Well I'v got a 94 T-bird SC that i'm looking to sell in order get a mustang and I was thinking if I do buy one then I could buy the supercharger. But after thinking about the belt problem he had and the problems people on here have had that these superchargers may not be good to go with. Would this supercharger be worth buying? Also, he blew his auto tranny in the car twice because too much power with the charger; Will a ford auto tranny be able to hold the power? I'v got a friend that has a mustang with a 347 in it; Would this supercharger be big enough to supply sufficient amount of boost? Please let me know

thanks
dan

**Psychdaddy** · 12:52 PM

ccwilms · 11-25-03, 03:58 PM

I tend to discourage spinning a powerdyne above 9 lbs. Powerdyne doesn't recommend it, and here's why: You might wonder why vortechs can make so much more boost and you don't hear much about their bearings going bad so much. Does vortech use bearings that are so much better than powerdyne's? No, they don't. So why can vortechs spin at a higher rpm than powerdynes without difficulty? The reason is that what really matters is the total load that the bearings are experiencing, and the rpm is only one part of that total load. With the powerdyne belt driven design, you have the stress of this belt tugging on both the input and output shaft, putting a lateral stress on the bearings. The vortechs have almost eliminated this lateral stress with the gear driven design. The shafts and gears are fixed rigidly in space and simply spin. So nothing is really tugging on the input and output shafts. With this lateral stress eliminated the bearing is free to spin up to higher rpms before it reaches its maximum load capacity. So while the powerdyne has the advantage of a quieter design that requires no oiling, it sacrifices the maximum rpm that it can see. It's not a bad design, you just have to know its limits. Now you can see why powerdyne's latest supercharger, which can achieve higher boosts, is a gear driven design.

quest · 02:16 PM

Hey does anyone have an installation manual for a 94-95 mustang GT. Also how about a list of parts to rebuild and some instructions. Thanx quest

Also any tips you guys have come up with to extend the life or increase power with this supercharger. (BD11a)
gandujar@page-stream.com