First OFFICIAL TWINCHARGED M20 BUILD

[kamotors]

I've run 23psi and its not too much, my car took it well. nothing maxed out and duty cycle was around 60% I believe. 23psi would be around 450whp on 91 octane on a good tune maybe a bit less depending on heat and losses from the supercharger.

really no point on running the turbo if your only going to run it at like 5psi. try to get that supercharge spinning slower, maybe back to m50 crank pulley? that seems easy enough, then dial up the turbo with a boost controller to get to your goal.

Your biggest problem is that the stock ignition system cant take much past 17psi(in my car not even 17psi)

if you want 23psi close up the gap and run wasted spark.

[Denny]

Why not turn the boost on the turbo down to 5psi to yield 18psi?

I've run 23psi and its not too much, my car took it well. nothing maxed out and duty cycle was around 60% I believe. 23psi would be around 450whp on 91 octane on a good tune maybe a bit less depending on heat and losses from the supercharger.

really no point on running the turbo if your only going to run it at like 5psi. try to get that supercharge spinning slower, maybe back to m50 crank pulley? that seems easy enough, then dial up the turbo with a boost controller to get to your goal.

Your biggest problem is that the stock ignition system cant take much past 17psi(in my car not even 17psi)

if you want 23psi close up the gap and run wasted spark.

Damn another thing I did not know the ignition system would crack up at 17PSI... please school me on wasted spark? what I need?

But I think the best would probably for me to bring down the boost on the SC to 7 PSI. The M50 crank is too small for a M62 it will only give me 3-4PSI. I would need to re-pulley the SC from a 2.6" to maybe a 3" and new belt...

I agree about the turbo it is the more efficient power adder it needs to be at minimum 8 PSI..

[Bullet Ride]

Just got myself caught up on your build Denny. Nice stuff! Glad to see you got it up and running.

For what it's worth, I had a similar issue with my DIYPNP and not being able to rev past like 2500rpm. The issue ended up being the value of the resistor in line with the jumper wire for the VR signal. The 18K resistor that the diyautotune application guide recommended didn't work with my car, it ended up being too large. I swapped to a 10K resistor and it fixed the issue. Maybe by moving the VR sensor a bit closer you counter acted the effect of having too large of a resistor.

[Denny]

Just got myself caught up on your build Denny. Nice stuff! Glad to see you got it up and running.

For what it's worth, I had a similar issue with my DIYPNP and not being able to rev past like 2500rpm. The issue ended up being the value of the resistor in line with the jumper wire for the VR signal. The 18K resistor that the diyautotune application guide recommended didn't work with my car, it ended up being too large. I swapped to a 10K resistor and it fixed the issue. Maybe by moving the VR sensor a bit closer you counter acted the effect of having too large of a resistor.

Hey buddy glad to see you :) thanks! Its been quite a journey. I'm almost there...idle is tuned..part throttle almost done...just got to fix the boost to be able to tune her fully.

Thanks for the info on the VR signal. I'm almost certain my kit came with a 10k resistor.

Had to cancel my dyno session of tomorrow night as I wont get my new SC pulley and belt by then..:(

[Bullet Ride]

Thanks for the info on the VR signal. I'm almost certain my kit came with a 10k resistor.

If I recall the kit doesn't come with a resistor specifically for the VR signal because I remembered having to take resistors out of an electronics hobby kit that I got as a present many years ago. Originally I had used a 16K because I couldn't find an 18K. Then I tried a 22K and still had the same issue. Then I tried a 30K and the car wouldn't rev past 1500rpm. So I knew that the resistor had to be smaller. I threw in the 10K and it worked fine.

[Denny]

If I recall the kit doesn't come with a resistor specifically for the VR signal because I remembered having to take resistors out of an electronics hobby kit that I got as a present many years ago. Originally I had used a 16K because I couldn't find an 18K. Then I tried a 22K and still had the same issue. Then I tried a 30K and the car wouldn't rev past 1500rpm. So I knew that the resistor had to be smaller. I threw in the 10K and it worked fine.

I built mine winter 2012 they must of upgraded their kits because I got one 10K in my kit.

**Update**

I just ordered a 3.0" SC pulley from ZZPerformance to replace my 2.6" pulley....(Happy I have a modular system where I can swap pulleys easy) just need a longer belt now too..thats going to give me 3-4 PSI less which is good as in total am still going to make 17-18PSI which will let me keep my OEM ignition. Keeps my SC at a lower temperature and still provide the low end Torque I love and If I want more power later I can just bring the boost up on the turbo :)

Its fine tuning right now...should have it all together very soon.

[Bullet Ride]

I built mine winter 2012 they must of upgraded their kits because I got one 10K in my kit.

And it was actually specified as a resistor for the VR sensor? Or did you just use a leftover resistor? Their application guide still says 18K.

That'd be interesting if they did upgrade their kit because I was having the discussion with them about the resistor value for the VR signal in the fall of 2011. I never did tell them directly that a 10K resistor ended up working for me, but I did post about it online. It's probably just a coincidence.

[Denny]

Just got myself caught up on your build Denny. Nice stuff! Glad to see you got it up and running.

For what it's worth, I had a similar issue with my DIYPNP and not being able to rev past like 2500rpm. The issue ended up being the value of the resistor in line with the jumper wire for the VR signal. The 18K resistor that the diyautotune application guide recommended didn't work with my car, it ended up being too large. I swapped to a 10K resistor and it fixed the issue. Maybe by moving the VR sensor a bit closer you counter acted the effect of having too large of a resistor.

And it was actually specified as a resistor for the VR sensor? Or did you just use a leftover resistor? Their application guide still says 18K.

That'd be interesting if they did upgrade their kit because I was having the discussion with them about the resistor value for the VR signal in the fall of 2011. I never did tell them directly that a 10K resistor ended up working for me, but I did post about it online. It's probably just a coincidence.

You are right my man they do still use a 18k resistor... I got it all confused its been to long since I built it.

[Denny]

**update**

Kind of update...lol..

While I waited for my new 3" pulley to arrive(it arrived this friday just need a longer belt now) I changed my sparkplugs got some NGK's 7es (2 step colder then stock) and gapped them to 0.23 instead of my old plugs at 0.28

Not related to this project but am already starting to put together my next project which is going to be my 1990 Red vert. I received my M30 (e34) mounts, got the engine harness and throttle body, etc...

I will be hopefully installing my new pulley and new longer belt this monday or tuesday so I can tune it...

So anxious to drive her again ...lat ride she gave me the ride of my life...lol... stay tuned.

[darvo]

Anxious to see and hear the video....

[Denny]

***Update***

Installed bigger pulley... installed NGK 7es a .23 gap and went for a little stroll ... car drives really well I am in love with MSII what a difference from WARchip! I am cruising a long at 2800-3000 rpm.. second gear then I attempt to press the pedal a little more then 1/4 travel...basically bang one shot 20PSI @3300rpm I immediately release the pedal Wow I'm stuck with a problem I just didnt see coming...TOO MUCH BOOST!! lol....



So now I think my only hope to control boost will be with the :

http://www.928motorsports.com/parts/boostlimitervalve.php

So I will order one tonight and set it to 17PSI and hopefully be able to enjoy my car...lol... Cant wait to get this beast under control so I can go race.

[twolitresix]

I dont think you need that valve, could there be something wrong with your signal plumbing? Where is your wastegate signal line connected?
If you connect it to the intake manifold, your maximum boost pressure should be determined by your wg spring (if above sc boost). But if you connected it to somewhere before the SC, you built quite a "boost-bomb" :D
Ex.: Connect wastegate-line to int. manifold, put 15psi spring in. Bam: 15psi maximum boost.

[Denny]

I dont think you need that valve, could there be something wrong with your signal plumbing? Where is your wastegate signal line connected?
If you connect it to the intake manifold, your maximum boost pressure should be determined by your wg spring (if above sc boost). But if you connected it to somewhere before the SC, you built quite a "boost-bomb" :D
Ex.: Connect wastegate-line to int. manifold, put 15psi spring in. Bam: 15psi maximum boost.

I'm trying to understand :( first I will explain the signals on my setup.

• Turbo wastegate spring 8psi and signal comes from turbo compressor.
• MSII computer is getting signal from intake manifold left nipple
• Boost gauge and fuel pressure regulator from intake manifold right nipple
• BOV(before throttle body) signal from SC intake (after throttle body)

Everything is getting proper signal and works very well. Problem(not really a problem) is the multiplication of boost on a twincharged setup. Which 10 PSI from SC + 8 PSI on turbo = 23 PSI and all that boost hit hard and extremely fast :)

The size pulley I would need to bring down my boost would rub on my upper rad hose and I dont feel like having a new Crank pulley built again.

thats why the BLV looks like a good option as it would safe guard my engine and bleed boost at high rpm so I can keep the amazing low end torque I have now.

[kamotors]

just pop a cheap ebay wastegate on a charge pipe to bleed off boost at a certain pressure, would work like that valve you linked....maybe

[twolitresix]

I'm trying to understand :( first I will explain the signals on my setup.

• Turbo wastegate spring 8psi and signal comes from turbo compressor.
• MSII computer is getting signal from intake manifold left nipple
• Boost gauge and fuel pressure regulator from intake manifold right nipple
• BOV(before throttle body) signal from SC intake (after throttle body)

Everything is getting proper signal and works very well. Problem(not really a problem) is the multiplication of boost on a twincharged setup. Which 10 PSI from SC + 8 PSI on turbo = 23 PSI and all that boost hit hard and extremely fast :)

The size pulley I would need to bring down my boost would rub on my upper rad hose and I dont feel like having a new Crank pulley built again.

thats why the BLV looks like a good option as it would safe guard my engine and bleed boost at high rpm so I can keep the amazing low end torque I have now.

No need to install a bigger pulley, in a twincharged setup you want as much boost from your primary (the SC in your case) as possible, for the fat powerband you mentioned.
What happens if you plumb your wastegate line to the intake manifold is that the turbo always adds as much boost as you need to reach your pressure goal. In a nutshell: You dont tell your your turbo "always boost the SC inlet to 8psi", but instead "always add enough boost to make it (for example) 15psi in the intake manifold"
If you have a 15psi spring or a mbc, plz try it. No need for that strange 200$ bleed valve...