Oddjob

I did some testing while trouble shooting a weak 87 turbo, and I have some questions on the APE chips.

For stock chips, the car runs approx 10-11 psi peak and drops to 9 or so at higher rpm.

APE stage I chips. The car runs the approximate same boost curve as the stock chips.

APE stage II chips (w/o jet in banjo bolt). Runs the same boost curve as the stock and Stage I chips.

APE stage II chips (w/ jet in banjo bolt). Peaks about 13-13.5 psi then drops off after the spike to the regular boost curve, down to 9 or so at high rpm.

I assumed that at least the stage II would have a different KLR cycling map and it would run higher boost than stock, even without the jetted banjo bolt. I also thought it should be peaking closer to 15 psi with the jet in.

Thinking I might have a leaking waste gate, I clamped the line from the CV and the car will run 15+ psi from 3500 to redline. But not sure that eliminates any waste gate concerns.

Im trying to track down and trouble shoot some problems with this car, so my question is not based on how well these chips will compare to other aftermarket chips; but is this the boost curves that APE chips should be capable of? And Im trying to get this car to run in stock trim for PCA club racing, so aftermarket mechanical boost controls are not an option (APE chips were tested just for trouble shooting a power loss problem).

Any tech knowledge or experience with what to expect for APE chips is appreciated.

Thanks.

special tool

Everything is working correctly. The 951 cycle valve is not a closed loop boost controller - it gets sent fixed look-up table values regrdless of the mechanical condition of the turbo, wastegate,etc.
You need a boost controller, or at least a poppet style check valve to get higher boost with any chips.

pk951

I have APE CHIPS STAGE 2 run them at 15 psi with a tial wg only way to hold 15 psi.

Oddjob

I was expecting to see about 15 psi peak and drop off to maybe 12-13 psi at high rpm with the Stage II in the 87.

Here is my logic on this one:

APE claims approx 270bhp for Stage II chips. If these chips do not alter the boost curve (other than the spike around 3500-4000rpm w/ the jetted banjo), they would not produce that much horsepower. Torque would increase at the peak boost, but the peak horsepower at approx 6k would not increase by 50bhp with just a different ignition/fuel curve in the DME chip. Are you sure the APE KLR chips do not alter the cycling valve duty cycle?

Ive run both APE Stage I and Stage II chips in my 89 turbo (street car) for years. And that car definitely runs more boost than stock. The 89 does not have a secondary boost gage so Im not sure exactly what the increase is, but it pegs the stock gage to redline and you sure feel it in the seat of the pants (it’s a big increase in power over stock). APE claims approx 290 bhp for the turbo S stage II which is around the same 40-50 bhp increase they claim for the 86-88 cars.

Even knowing that the K26/6 wont push as hard at the top end, I don’t feel a similar seat of the pants increase in power with the chips in my 87 car. And that makes sense, since Im not seeing an increase in boost across the rev range.

Based off of this, is something wrong with the car (intake/exhaust, etc) or something wrong with my logic (operator headspace and timing)?

Jake951

To increase the boost, you just need a smaller jet size in the banjo bolt. As I recall Autothority supplied 2 or 3 different jet sizes and you picked the one that produced the correct boost in your car.

B951S

I have stage II APE chips in my 89. I also have just installed a Profec B spec II EBC. I have limited boost to 14psi as I thought that the APE chips ran lean at the top end WITH a dropping boost curve. Holding 15psi to the red line would lean out even more right??

rhesus

Chips by themselves won't change the boost, just the fuel maps.

Jake951

Yes, you'll probably run lean on top with 15 psi all the way to redline. As I understand it, the APE chips are mapped for a dropping boost curve, as you get with the banjo bolt, not a flat curve.

Oddjob

>"I have APE CHIPS STAGE 2 run them at 15 psi with a tial wg only way to hold 15 psi."

What did it drop off to before you added the Tial waste gate?



Ive got to play devils advocate with some of this:

If the aftermarket KLR chips do not increase boost by changing the duty cycle for the cycling valve, what do they do? Why have the extra chip at all? If programmers have gone to the trouble of remapping the fuel/ignition curves, why not tackle the cycling valve duty cycle?

I would not expect to see peak 40-50 bhp increase at 6k rpm, if the chips (KLR) are not increasing the boost. Remember, the jetted banjo just spikes the peak boost right after wide open throttle, because it delays the system's response (takes 1/2 to a full second for the reduced air flow to build up enough pressure to open the waste gate). So if the KLR chip is not altering the boost curve, by 6k rpm, the boost would be back down to stock which = stock bhp (plus a couple bhp for the more aggressive ignition, but not 50bhp).


No one running APE Stage II chips in an 86-88 turbo w/o other engine upgrades, that can throw out some boost numbers at peak and high rpm?

Sorry for beating a dead turbo on this one....

Jake951

If the jet size in the banjo bolt is small enough, you will see more boost than stock, even at redline. When I had APE chips, I played around with jet size. When I had it set up for 15 psi peak, I still had about 12 psi at redline, which is more than the stock setup produced anywhere. When I replaced the jetted bolt with an unjetted one but with the APE chips in place, the boost was essentially the same as stock. The APE KLR chip merely removes the stock 6500 rpm rev limit and raises the overboost protection limit. The increase in boost is produced by the jetted banjo bolt.

Oddjob

>"When I had it set up for 15 psi peak, I still had about 12 psi at redline, which is more than the stock setup produced anywhere. "

Thats pretty much what I was expecting/hoping to see.

Apparently overboost protection is controlled by the DME unit/chip as well as the rev limit. I found that out from some threads here (rennlist) and then looked up a presentation made by Paul Hensler (director of power train design at Porsche AG) to SAE when the 944 turbo was introduced in DEC 85. Refering to the DME brain: " the system in the turbo has overboost protection in case of air leaks in the pressure system which could push the turbo charger to unacceptable levels. The fuel injection system measures airflow and compares it to values stored in the control system. Should the air flow exceed theoretical flow values by ten percent for three seconds, fuel injection is interrupted..."

However he also states there is a feedback loop in the KLR for boost pressure that compares actual pressure to a desired map and controlled by a governor, which I think most everyone generally agrees does not exist.

special tool

Sure, it is there. It is a clear line from betwen intake runners 3 and 4 and goes to directly to the KLR. The klr recieves it. and if it sees something it doesn't like, will cut igniton and/or fuel. It can also send all of the manifold wastegate signal air to the wastegate (via the cycle valve), to make sure you don't have any fun. But it is always a fixed look-up table, not a sophisticated closed loop boost controller which moniters itself - like an avcr.

Oddjob

As I read it, the Paul Hensler article implied that the KLR system makes corrections by modulating the cycling valve to achieve the desired boost curve; which I dont think it does.

The DME cuts the fuel when it determines there is too much airflow through the AFM, which is the dramatic cutout stumble that everyone refers to as the overboost protection. The KLR can detect an excessive boost condition from the manifold pressure, and it will trigger the limp home mode (1.3 bar max boost).

These two responses appear to be separate, because you can trip the DME overboost protection w/o the KLR identifying an excessive boost problem (because it wont store the fault code or drop to the safety boost level). Ive done that many times. An intake leak after the turbo can cause high load/airflow through the AFM so the DME would trip the overboost fuel cutoff. But because of the leak, the manifold pressure would not be excessive to alert the KLR.

But without getting into more DMR/KLE/bungo bolt jargon.... I was just looking for some examples of what boost guys are actually seeing with APE Stage II chips in an 86-88 turbo.

Thanks.

Tomas L

I have an 88 turbo S with APE chips. It has the same KLR as the later cars so I don't think the chip is identical to yours.
I get approximately 0,2 bar more boost with the APE than with stock chips.
This difference exists regardless of whether I have the jet in the banjobolt installed. With the jet however I get 0,1 bar more boost for both stock and APE chips.
Because the jet is located far away from the WG it will cause a delay in the regulation. However the main purpose of the jet is to increase boost over the entire rpm range. The principle of boost regulation with a CV requires a restriction in the flow path before the CV or else we would bleed away all boost like a pop off valve. There should be a restriction in the in the inlet of the CV. What APE does is to put in a smaller restriction to lower the pressure signal from the CV to the WG further.

3 Turbos

This is what I have, maybe this info may help;


** SRF MAF Level 1 (with K&N cone filter)
** Garret Turbo Level 1 (water/oil cooled)
(T04B w/#8 46mm compressor stage 3 turbin wheel)
** Tial 46mm Wastegate
** ARC2 - piggy back computer
** ARM1 Split Second air/fuel indicator
** Greddy Profec B adjustable boost controller
** VDO Mechanical Boost gauge
** Billet adjustable fuel pressure regulator
** Stainless steel braided fuel lines
** SRF 2.25" Intercooler Pipes
** Chip is a Autothority version 2.5
** Stock exhaust with no cat


With this setup I have on my Profec B, it is set at "14.7lbs on low
boost - **** is maxed" and "18lbs at high boost - **** at midway/12
o'clock". Balance is set to 3 o'clock (towards sharp).

FYI, no matter where I turn the **** for high boost, it will not go
beyond 18lbs-19lbs, although I understand my turbo should be
able to hit 30lbs, and my wastegate should hold 36lbs.

I can hold max boost in the low boost setting of 14.7lbs all the way
to redline on "low boost control " - but when set at 18lbs, I can only
see 18lbs until 4800rpm, then it drops back to about 15lbs. I think
it was able to hold 18lbs to redline before - but not sure. It does
seem to hold 18lbs in 1st and 2nd gear and sometimes 3rd gear
if the weather is cool enough but will still drop back to about 15lbs
when I pass 4800rpm most of the time. This by the way is on
100 octane fuel.

Is there something wrong, or do I need to change chips or is there a
leak somewhere. I've tightened all the vacuum lines on top of the
engine including the 2 big hose's for the boost controller. My fuel
pressure at idle with the vacuum connected is between 38lbs and 40lbs
- I've tried 42lbs also - but I still have the same problem.

Bottom line: If this is normal, what can I do to get it to maintain 18lbs to
redline in all gears when in th high boost setting?

Other than that small problem, the car runs great!