TF

Carl
I understand no MAF but why is the blow-off valve recirculation removed. It appears the blow-off valve now dumps to the atmosphere

Jfrahm

With a MAP sensor the ECU only takes into account the air in the manifold (by pressure) so it does not matter if you dump or recirculate. With a MAF the air is measured at whatever point the air passes over the sensor (generally before the compressor.)

Some modern systems use both MAF and MAP. With temperature it's a good basis for the fuel maps.

-Joel.

Carl Fausett

Correct - we are now dumping the BOV to atmosphere. Because of the modern EMS, we also have gotten rid of that pesky (and slow) Idle Air Controller, and the MAF. The MAF couldnt measure our air flow anymore anyway... so its gone. The MAP and MAT are all the system needs now to fuel the engine correctly.

We expect smooth idles, flat fuel lines, and instant throttle response. :-)

TF

Understand you don't use the MAF with the Electromotive but don't understand removal of the air controller. How do you get the added air required at idle. I have the SC'd 944 with Electromotive and have had problems with idle.

Carl Fausett

TF - there are several ways to get and control an idle with an Electromotive system. But if you left your IAC installed - that's your problem.

The IAC (Idle Air Controller) is a "dumb" device (as in unsophisticated) and we have found also very slow to respond. Responsible for a lot of idle speed "hunting" because it reacts to slowly, too much, and too late.

Its purpose is to prevent the motor from killing when you suddenly snap out of the throttle, but the electromotive system will perform that function so you don't need it anymore. Remove it.

pudjnr69

Carl, is there an auto belt tensioner in there currently? What diameter crank pulley as SC pulley? What boost pressure are you expecting?

Carl Fausett

You cannot use an auto-belt tensioner (spring type) in a high load system like this. Sprung belt tensioners are useful on low load systems. We are continuing to use the stock belt tensioner system with this kit, that is the turnbuckle under the engine at the front. We have had no problems with that and see no reason to change from it.

Some owners have reported that they broke the mounting ears off the air conditioner on non-supercharged cars with the stock belt tensioner, but we believe they failed to loosen the pivot bolt on the compressor before trying to adjust the belt tension. The pivot bolt should never be more than snug - never tight. Then the factory belt tensioner works well.

The stock crank pulley is roughly 5" in diameter and our new crank pulley is 6". Then we use an under-drive alternator pulley to put the alternator back into its rpm range as designed.

Carl Fausett

The 968 is up and running with the Stage II kit on it now. We were able to wire the Tec-GT system to use the factory camshaft sensor so we have full-sequential injector timing.

Our first dyno appointment is currently scheduled for Friday evening. We will be looking at belt tracking and slip under load, and whether the 40 lb injectors that are on this car now are large enough and fast enough.

We'll see.

wpb968

Carl,

Keep up the great work. I appreciate all of your efforts to sort of the details and get it just right. Please keep us posted with the results!

Carl Fausett

Thank you.

Just strapped it down into the trailer, we leave for the dyno (about 1 hour away) at 2:30. This is first dyno run of the system, it may or may not produce final results, depending on whether these 40# injectors can keep up, or will we have to come back and install bigger ones.

We will also be testing for belt slip of the new drive system today.

I'll let you know what happens.

Carl Fausett

The trip to the dyno with the 968 Stage II kit went flawlessly and we have no further major work or parts to replace.

We ended up at 300 HP at the tire, 350 at the motor, and it is very safe, reliable HP. We ran it for more than 2 hours on the dyno in all kinds of conditions, ranges and loads. Its really nice.

There is absolutely no belt slip and the belt tracks perfectly. The engine tune is flawless. We really worked hard on all rpm ranges, all loads, all gears. Its ready to race.

I have dyno charts to post when I get to the office today. I'm sure you have questions, I have answers. I plan to be in the office this afternoon to post the charts and answer questions.

I think I will start a new thread about this, as it is a new product. The design goals for this Stage II kit were quite a bit different than those for the Stage I kit. You can review the initial design goals in Post #1 of this thread.

Carl Fausett

A new thread was started just for the new Stage II kit, but in case you are not subscribed to that thread, here are the results of the finished 968 Stage II kit.

296 HP at the tire, 348.24 HP at the crank. Stock engine.

Carl Fausett

I was able to bring this kit in at the same price as before, so there is no price increase.

It is available as a "Mechanicals Only" kit for the 968 owner who wants to develop their own fueling solution; and as a complete kit for those customers that want a proven, complete kit including Engine Management.

Mechanicals Only 968 Stage II kit: $5395.00

Complete kit with EMS: $7595.00

Webpage for more information:
http://www.928motorsports.com/parts/...percharger.php

Carl Fausett

With all the interest in our Stage 1 kit, and so many trying to modify it for track use, I thought there would be more activity and conversation on this Stage II development.... a little disappointing now that we took it back in and re-designed it to use the double-sided belt drive that the forum members were asking for, put up 50 HP more than the Stage 1 kit, and kept the price the same as the previous Stage II kit.... why no interest?

Carl Fausett

I was putting this together for a customer, and thought you might all want to know this.

If you have our earlier Stage II kit with the single-sided belt, you can easilly upgrade to the current Stage II setup with the double-sided belt.

You should have the upgraded (larger) crankshaft pulley, and larger injectors already.

If so, you will only need:

1) the new Stage II supercharger mounting bracket $ 136.00
2) the new Stage II double-sided belt $52.00
3) the new Stage II supercharger pulley $67

Total: $255.00

That will give you all the mechanicals for the new Stage II kit.

Then you will still need to come up with more fuel, control the injector events, and retard the timing under boost as needed. And the best solution I have found for this is the Electromotive kit for the 968 at $ 3120. Then you have complete tuning flexibility in the future and no idle issues.