FredR

A,

You deserve the "boot" for this!

After all the work you did you left the stock boot on?

What's the betting the dyno self destructs before your motor?

Regards

Fred

ptuomov

Comic relief interruption.

I have an anti-lag idea. Not that the car needs any, but still...

You recall that as part of the twin turbo install, we cut the WOT signal line to the EZK. This is necessary, because the EZK goes to a WOT ignition advance vector and one does not want that. As a belt and suspender approach, the WOT map is also disabled with Sharktuner.

Here's my idea. Cars with cruise control must have a clutch switch. Depending on how the clutch switch is wired, one may be able to get a signal from it. Hook that signal to the EZK WOT connector. Then enable the EZK WOT ignition map and set the EZK WOT ignition map to be stupidly retarded. I think most you can do with Sharktuner is zero degrees.

It may be possible to launch with higher rpm and shift the throttle open with this setup. When the clutch is depressed, the engine makes less power because the ignition is so retarded. However, the charge should burn in the exhaust port and the exhaust gas should be really hot and turbine should spin like crazy.

For the visual effect, one can have an additional dashboards switch between the clutch switch and the EZK:
http://ecx.images-amazon.com/images/...500_AA300_.jpg

Good bye transmission...

In any case, I don't really want to do that but I am just saying that maybe one could.

Back to the regularly scheduled programming.

Lizard928

Actually Tuomo, you could def do that, and it would work a treat!

Just set it so that it would go to a max of around 3500RPM. This way, you could also push in the clutch, put the pedal down, have full boost at launch too........

dprantl

Why do you hate transmissions and clutches so much?

Dan
'91 928GT S/C 475hp/460lb.ft

AO

OMG... I just got a tingle "down there." What a friggen hilarious idea.

ledee416

very cool. what did you use for internals?

Hilton

LOL.. I just posted a link to this thread in yout thread. He's using a completely stock 87 S4 motor with the original factory head gasket.

His stated goal is to find the limits of the factory internals, so he can work out how much boost/power to go with on his (already) built engine with lower compression and valve/headwork (altho' his "built" motor is still using stock crank and Porsche pistons IIRC)

These posts in this thread:

https://rennlist.com/forums/7833429-post283.html
https://rennlist.com/forums/7764427-post244.html

ptuomov

It might work during shifts but it wouldn't work when braking to a corner where you in theory really need the anti-lag. But here's an idea: Wire the clutch position sensor also to the LH idle switch and set the idle set point to 3500 in ST2! (Don't actually try that at home, please.)

Another fun scheme would be to connect the bypass valve to the exhaust manifold via a check valve and set the lowest load row on LH extremely rich. When you lift off and brake, the throttle slams shut. Boost surges and the bypass valve opens. The boosted air flows to the exhaust manifold, where it meets the unburned fuel from the overfueling. BANG and SPIN! ;-)

All this is fairly academic, as I can't get the engine to rev at 3500 with throttle open ever without the turbine having already spooled. It's not fast, it's instantaneous, as long as the engine spins above 3500 rpm.

I hate my clutch because it's a POS Spec 3+ piece which stutters and shudders embarrasingly every now and then.

I don't hate transmissions, I like transmissions. That's why I have two!

I don't know for sure, I've never checked. With high likelihood, they are just as they came from the factory a quarter century ago.

Gr8godbob

You Americans are so lucky with the space. I can just squeeze into mine when she is parked in the garage.

AO

It will get better... promise. But I remember this pain too.

ptuomov

No, it has not gotten better and it will not get better. What happens to most users, though, is thata they get used to the bad clutch. There's "bedding" in the Spec 3+ clutch, there's only bedding in the users brain. I am more immune to this than most people because I also drive a 991 GTS convertible with a working clutch.

123quattro

I have anti-lag on my 200 20v Audi. I'm using the clutch switch as the input when the function is enabled via a toggle switch. On my car I'm going as far as -60 BTDC to hold engine speed at 6500. It's works very well to spool the turbo and for flat shifting.

What I have is nothing like you have, but here's how mine works. Maybe it will give you some ideas. When the function is active it does nothing under 6500 rpm. Above that speed it will pull timing with closed loop control on the engine speed. I set the max retard at -60 because that is where stable combustion ended for me. When active it also adds 0.2 lamdba to that standard mix to help cool the turbo. So, under full load I'm around 12.5:1. During shifts the A/F ratio momentarily drops down to around 10:1 to help keep the turbo from dieing a fiery death. That said, things still get hot really quick. I've melted some of the ceramic coating on my header and had to re-weld a couple joints. However, I can get ~30 psi of boost with no load on the engine. It takes about 1 second to build that amount of boost.

In day to day driving having anti-lag on can be a little annoying. It can go active on some shifts when you don't want it. Not a big deal, but it sounds weird and dumps a lot of heat into the turbine.

As far as keeping the turbo spooled all the time what you mentioned sounds a lot like this.

http://www.bufkinengineering.com/Umluft.htm

It works, really well. You'll also destroy the turbo every couple hundred miles of driving.

AO

Buy an auto next time...

123quattro

I have never seen a really strong aftermarket clutch that didn't shudder under light load. I think it's something you'll just have to live with. I have a clutchnet 6 puck sprung hub in the Audi rated at 500 ft-lb. My truck has a SPEC full face twin disk rated at 1000 ft-lb. There is no finessing them. You have to be on the gas and quickly engage them. I don't think either are nasty to drive in traffic though.

Factory twin disks have nice release, but that's all I've ever seen with 600 ft-lb capacity that don't stutter. Stuff like what's in the ZR-1/ZL-1/GT-500.

Lizard928

I went with a divided T4 housing, so that below 5PSI I can close off one port to bring the boost up much faster.