I've got a freshly rebuilt Vortech V2 setup on my F20 with the following parts:

ID 1000's
AEM fuel Rail & AEM FPR
FullBlown 340LPH fuel pump
ASP Racing 4in pulley(12psi)
AEM 1052 non UEGO
Berk 70mm HFC
Stock Exhaust with Invidia Y pipe
SOS 3 bar map sensor
NGK BKR8EIX Spark Plugs

Now my question is, when I had it tuned on a dyno a few months back it made 320 whp @ 10 psi on a mustang dyno. I've seen other guys on here make closer to if not over 400 hp @ 12 psi. Now I know that the mustang dyno is the heart breaker dyno for good reason but should I have made more? The car has yet to see 12 psi and i'm thinking that it's the belt that needs tightening but on the dyno it only made 8 psi and then jumped to 10 psi. It wasn't touched on the dyno and confused me when the tuner said that it jumped from 8 to 10 psi.

 

Mustang dyno's read considerably low than others.

Granted, numbers are just that...numbers. The dyno is nothing more than a tuning tool, so keep that in mind as well.


FWIW. My old car made low 300's on a mustang dyno and over 400 on a dynapack.

The local "mustang" dyno in town, stock S200's put down 160-170.

Food for thought

 

Small pullies often slip. Sometimes they need tightening and sometimes they need "belt dressing" (basically adhesive asphalt to help traction on the pulley).

 

This.

I dont trust dyno numbers. I also believe dyno is nothing more than a tuning tool. Only way to find out if your numbers are legit is to hit the track or race someone with similar dyno numbers.

 

Yeah, baseline run was 189 whp Once I get some kinks worked out, I'll be headed to the track.

 

Given your exhaust setup, 10 PSI, the novi 1000, and the mustang dyno those numbers sound about right.

Mustang dynos read lower. Your exhaust is also probably holding you back a few horses. In addition, I found that the novi 1000 isn't going to give you the same results as the newer 1200 PSI for PSI.

If you look at the dyno sheet it should be easy to tell if your belt is slipping. I guess I don't know what it "jumping" PSI means. it will make more boost with more revs so I would think it would always jump. The sheet will tell. WIth a smaller pulley you will need some sort of pry bar to get leverage on the pulley when tightening. Not crazy tight but I was unable to get it tight enough holding the pulley in place by hand.

when i first started my belt slipped at 8PSI. I just tightened it and haven't had a problem since.

I had a similar setup as you and made 350 at 12ish PSI on a dynojet. Although I didn't have the map sensor or the FPR which I am sure would have helped get me more horses up top. I don't think it would be easy to get 400rwhp with a novi 1000 and 12PSI.

 

As stated above its only a tuning tool . So dont let the numbers bruise youre ego ! Mustang dynos read the lowest and dyno packs read the highest . Any others are in the middle of the two . If the car feels good and strong them thats all that matters .

 

If the boost "jumps" instead of linearly increasing with rpm, then really look at pulley slipping.

 

Yeah my money is on your belt slipping a bit. And 320whp on a mustang dyno is about right. Most Centrifugal blowers generally put down 350whp at 10psi on a Dynojet, which is a pretty consistent average numbered dyno. Check your belt tension and enjoy your car, it seems healthy

 

+over9000 for Mustang Dynos reading low and your numbers being around where they should be.

The guy who runs my local Mustang Dyno says from his experience that it can read up to 20% lower than a Dyno Jet.

Sounds plausible to me. As some have said though, dynos are definitely a tuning tool. Don't take the numbers too seriously.