Speedtoys

I would not be pulling the engine.

But I have creative people in the 'hood.

terry gt

Dyno is booked for this afternoon, I am not expecting a HUGE power incress .Considering the stock exzost , and O tuning . I am going to install the MSDS headers next and also a X and 2 1/2 exzost . Then I should see the full results of the cam change . Any guess as the the dyno results ?

Speedtoys

5 Kiborts, but 6 if you can get a wider contact patch.

John Speake

What were the dyno results ?

Lizard928

Ok, so an interesting update for this.

Terry did get to the dyno and did a pull.
What I can tell you is that we have found the limit for the stock exhaust/cats.
The car had pretty much no change in power with using the stock cats/exhaust.
Everything on the chart shows that the cams are timed properly, and that the flappy and everything is working.
It is interesting to see that there is less of a dip between flappy open/closed, and the power does not fall off above 6,000RPM. The car was getting into the 10:1 AFR in the upper RPM as well. So with tuning there is power to be had there.

Next thing we are doing is MSDS headers with a dual 2.5" exhaust (with X). I expect that we will find the real power once this is done.

With my car, I have a homemade X with the Vibrant X piece in the middle (not very good) and 300CPI cats, I picked up 25RWHP over stock with the cams advanced 5 deg.

So the simple answer to this is that one needs to do an X pipe at least with these to be able to make the proper gains.

Speedtoys

"Terry did get to the dyno and did a pull."


THIS THREAD....

John Speake

Certainly the additional power will be made at the top end of the rev range.

Was the torque curve also essentially the same as stock ?

Lizard928

Yes, the torque curve was similar to stock, but it was flatter.

Lizard928

The dyno runs.

Speedtoys

So..this was an otherwise stock car..no intake/exhaust mods?


Turned about the same numbers as I did with Xpipe/cats/RMB?


However, it seems that peak HP way way higher than mine was..and didnt fall off.

I guess, Id haev to see similar setups, to see what the difference really could be.

Lizard928

That is correct, bone stock, original cat. This is the ONLY change made.

With an X pipe (and no cats), you will get a big improvement as the exhaust can then flow.

terry gt

The performance shop where I did the dyno runs is owned by a very talented engine builder . He felt the exzost was the point of restriction , said its acting like a big restrictor . just look at the torque curve , flat . He also said that with the cams / exzost and the fuel ratio brought to 13:1 that I should see 350-375 RWH . So I will get started on the exzost .

the flyin' scotsman

ok.......so the hp curve is flatter and the net results are similar to before the cams.

I know for absolute surity removing the cats and adding the modern X was considerable SOP and much free reving engine to my car with stock cams and untuned PEMs so itll be very interesting to hear what the X does with this car.

Also what hp gains were expected from only the cams then any other predictions with what Greg is developing with cranks, bigger displacement and longer stroke?

Lizard928

Malcolm,

If you were to go with a GB 8,000RPM bottom end 5.0L with slighly worked S4 heads, my cams, headers, pull exhaust, and proper intake, 500BHP should be easily achievable.

I know that with a proper exhaust system that the gains should be substantial, over just an exhaust system.
Also Malcolm, iirc you got a ride in my car with Cams, I could be wrong on that though.
I do know Dan (S4Ordie), and PorKen got a ride in my car with the cams and they both agreed that the car moves very well.

Rob Edwards

I can totally believe that you're now exhaust limited, I had the same problem with the stroker with a completely stock exhaust (and a very conservative sharktune) . Here's the dyno curve from May 2010 (the only one I've managed to do), you can see the inflection point at 4600 rpm, the slope of the hp curve just flattens out, just at the point it should be coming on cam. I have not had the chance (pathetic, I know) to get back to the dyno after doing the headers and 2.5" catback, but it certainly drives like a different car. I will bet Terry will have the same experience.