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Richard Jemison
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Shankle info

Nice explanation Richard but I'm just the messenger for the Shankle write up below.
But proven incorrect. Today the ability to measure every interaction in an engine has changed much.

Your link is illegible...

If you are running Shankle cams using 102/102 LCs move them to 104/104 (and even wider) and give us a report!

Ho Ho Ho:santa:
 

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The information in the Shankle catalog is at odds with everything that I have experienced or read elsewhere. I think that somebody did a poor job of proof reading it.
 

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Discussion Starter #23
Merry Christmas. I stopped by my shop on the way back home and grabbed a few images off my dyno PC.

First up we have the before and after. The before is immediately after I got the car. It took me a month to diagnose the running problem. It turned out the main ecu and injector power relay had been swapped for an identical looking, but incorrect relay. The ecu was getting about 4 volts somehow backfed through the injectors or sensors, I'm amazed it ran at all. Would have been easier to diagnose if it didn't run, haha.

Aaron
 

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Discussion Starter #24 (Edited)
So with the ecu power issue fixed, and the car running about as expected I decided it was time to test a few things.

Between runs 20 and 34 I tweaked on the AFM, basically moving it one click each pull. Eventually I made myseld an additional 4 or so whp. Run 20 peaks at 89.55 and run 34 is 93.47

I noticed the inlet to the stock airbox was pretty small, so I removed it from the car, grabbed a hole saw and added a second hole. I described the procedure earlier in this thread, but here is the before and after with no other changes to the car. I was astonished to see a solid 5whp gain.

Aaron
 

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Discussion Starter #25
I kept tweaking the AFM, but really didn't get any better results. Then on one pull the VVT connector actually fell off and hit the fan. I noticed a jump on top end power the instant the VVT closed. That was a surprise. Somewhere around pull #52 my O2 sensor flange broke off the exhaust, and I gained a couple more whp. I'll try and address the O2 sensor bung area, and perhaps see if I can free up some exhaust flow tomorrow.

So right now I have 100whp and a loud exhaust leak, haha.

Oh, the jaggedness of the graph makes me thing the engine could really use some more ignition timing, but of course that is locked by the ecu.

Aaron
 

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Nice work. It is interesting that your rich dip moved from about 3700 rpm in the first chart to 4300 rpm in the 3rd one. I presume that it is due to the change in intake cam timing.
 

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Discussion Starter #27
I think you are right. My goal is still to put a rom controlled switch in their to deactivate the VVT around 5000 rpm. I have one, but it seems I need a tachometer filter on it as it doesn’t work correctly yet.

Aaron
 

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Richard Jemison
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VVT

I think you are right. My goal is still to put a rom controlled switch in their to deactivate the VVT around 5000 rpm. I have one, but it seems I need a tachometer filter on it as it doesn’t work correctly yet.
If you cut off the VVT you will retard the cam 7 degrees which is 14 crank degrees.
Best to retard the cam 1 notch at the sprocket as that will improve cam timing from engagement of the VVT to redline.
 

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May be I am not right but VVT works only till 1650 rpm and has only two positions.

When crankshaft speed exceeds 1650 RPM, the spool of centrifuge valve 14 closes the oil passage C; oil pressure rises in the circuit, is transferred to chamber B, plunger 12 is pushed axially to the right. The helical gear 3 and the splines 11 causes a relative rotation between support 7 and sleeve 5 to take pace; the timing chain is thus rotated with respect to camshaft . As a consequence of this relative rotation, the intake valves open 44o 34' BTDC instead of 24o 34' BTDC.
When crankshaft speed is less than 1650 RPM, the oil passage C ls open: oil pressure is relieved to such an extent as to fail to actuate the plunger; restrictor A, however, keeps oil pressure high enough to ensure proper lubrication of bearings in this case the intake valves open 24o 34' BTDC
The increase of power on the graph is caused by the open throttle switch (approximately at 72 degrees).
The corresponding electric signal causes a greater fuel flow and the simultaneous switching off the lambda sensor circuit
 

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Trained (ex)Professional, , 1953-2018 RIP,
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Then on one pull the VVT connector actually fell off and hit the fan. I noticed a jump on top end power the instant the VVT closed. That was a surprise.
...and expected as written back in post #9.
Please click on this Web Cam link and scroll to the bottom of the page to ‘Varying Lobe Separation Angle’ and ‘Advancing/Retarding Cam Timing’ to see why your result should come as no surprise.
 

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That is true for the centrifugally operated VVT. The later models have a solenoid operated VVT
Aaron has S3 QV with L-Jetronic. I provided a description from 1984 S3 Shop manual which works for all Jetronic cars. But the operating logic is the same even for Spider/75/155/164 8v TS with Motronic 4.1. VVT has only two positions which switched at 1600 rpm. The main difference between Jetronic and Motronic VVT is operating range - 20 degrees for Jetronic and 30 degrees for Motronic.

I think the power increase happened not due VVT disconnection, but due full throttle switch. As Aaron described at facebook it happened at 75% of the throttle opening which is matching to full throttle switch position engagement.

I would check the oxygen sensor and full throttle switch. Even if you see the shop manual, if NO PEAK OUTPUT. MAXIMUM SPEED NOT REACHED there is no any procedure to check VVT. All procedures are about throttle valve, throttle switch, fuel pressure and AFM
 

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The first 2 or 3 years of the USA versions of the L-jetronic Spiders had the centrifugal VVT. The later model years of L-jet Spiders had the solenoid controlled VVT. The solenoid version triggers the VVT device at higher RPM & with the throttle wide open (or nearly so).
 

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Trained (ex)Professional, , 1953-2018 RIP,
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There are 3 documented VVT types that I found.
1980?-1984 uses centrifugal actuation at engine speeds exceeding 1650 RPM. (1)
1985-1989 have a TPS (Throttle Position Switch) actuated VVT when throttle opening exceeds 55 degrees. (2)
1990-1994 have the VVT controlled by the ECU. (3)

(1) 1982 Bosch/Alfa L-Jet manual #3004
(2) 1985 Bosch/Alfa L-Jet manual #3651
(3) 1990 Spider workshop manual #4363 and 91-94 manual #4466
 

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Papajam, thank you for the manuals :) Just want to confirm you words

For MY85-MY89 models
TPS (Throttle Position Switch) actuated VVT when throttle opening exceeds 55 degrees. Switch works as on/off, there are only two positions of intake cam shaft, the difference is 7 degrees.

Still do not see the reason to turn off VVT as based on the attached the standard position of the shaft should not give any advantage for the peak power.
 

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Richard Jemison
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VVT

Well you can measure and mark the amount of advance on a VVT unit
and re-mark the cam`s timing notch (mark) so that when it is advanced the total advance leaves the cam position at 104-105 degrees.

Simply plug one of the oil pick-up holes on the cams bearing journal and use air pressure on the other hole to pressurize the unit. (On solenoid activated units the center "Button" must be pushed in.)

To test "Performance by driving as Ed does it`s simple to just move the cam back 1 or 2 notches on the VVT to get activated LCs at 104-105.
 

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My motor with big cams and 45DCOE's could use some help below about 2700 rpm and if I were doing a custom VVT it would retard the intake cam at about that point. I would not use throttle position to activate it.
 

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Aaron: Where are you disconnecting the VVF? I assume with the wiring on the solenoid attached on the front of the valve cover.
I have an 1987 Spider and find this VERY interesting.
Mike
 
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