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quattrobros twincharged audi 90

PostPosted: Sat Dec 14, 2019 1:23 am
by quattrobros
I've been meaning to make a build thread for months now.

If anyone is interested in the history of this car (October 2014 - May 2018) i have somewhat of a build thread on that other website under the username 8990q.

Last year the car shut off on me and would not re start. I thought it was the distributor. So i installed a new one and turned the car on and then proceeded to listen to the valves hit the pistons. Turns out the distributor was fine but rather the timing belt slipped and while installing the new distributor everything was in time other than the cam gear. I'm sort of happy that happened as it is what caused me to do this build.

Here is the current setup

Engine:
-3b block 82mm bore
-FRP 9.1:1 pistons
-Scat rods
-ARP hardware
-Coated bearings
-Supertech valve springs
-terrybullowon timing gear
-Autotech cam gear
-Tubular SS manifold
-Holset hx35 (turbo lab of america 0.82 ar exhaust housing)
-Eaton m62 (AAN crank pulley machined to accept supercharger pulley)
-Nissan throttle body as supercharger bypass
-Mishimoto Evo 10 3" thick intercooler
-Coil on plug conversion
-Vems

Drivetrain/Suspension:
-6 speed 01e
-Sachs zf clutch
-KEP 6 puck ceramic disc
-4kq driveshaft
-custom coilovers (koni struts & eibach springs)
-5 lug conversion (b5 a4 rear hubs on all 4 corners
-200 20v BBS wheels
-Coupe quattro g60 brake calipers
-4kq front sway bar mounted in the rear

Chassis/misc:
-Electric power steering conversion
-b4 cabrio carbon canister mounted in passenger fender
-wiper fluid reservoir mounted in drivers side fender
-JHM b5s4 solid shiftier modified for b3

Here are some pictures i took along the way. Currently the car is done in terms of fab work and whatnot. Still have yet to start it or drive it but that should happen any day now. Everything in terms of supercharger control/wiring and plumbing is in place. The plan is to first do a break in with just the turbo at spring pressure then eventually get larger injectors and throw the supercharger belt on for some twincharge goodness.

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Pistons from Jeff
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Re: quattrobros twincharged audi 90

PostPosted: Sat Dec 14, 2019 1:25 am
by quattrobros
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Re: quattrobros twincharged audi 90

PostPosted: Sat Dec 14, 2019 1:27 am
by quattrobros
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Re: quattrobros twincharged audi 90

PostPosted: Sat Dec 14, 2019 1:39 pm
by PRY4SNO
Mmmmmm, twincharging.

The final frontier of 20vt territory.

Can't wait to see how this goes.

Interested in the details of your clear cam gear cover.

Re: quattrobros twincharged audi 90

PostPosted: Sat Dec 14, 2019 2:10 pm
by quattrobros
https://www.amazon.com/Royal-Imports-De ... 522&sr=8-1

I didnt do the best i kind of rushed it but its the perfect size.

Also the brand name is "royal imports" which could not be more fitting haha. It has a little logo on the bottom of the vase.

Re: quattrobros twincharged audi 90

PostPosted: Sat Dec 14, 2019 5:17 pm
by mrdeye
This is cool!! Looks like a real banger!! When it’s finished that thing should rip! Good luck with it.
:beer:

Re: quattrobros twincharged audi 90

PostPosted: Sun Dec 15, 2019 12:52 am
by quattrobros
It starts! It idles wayy too well for some reason.

https://www.instagram.com/p/B6FG8henMPN ... nrmxhg95zt

Re: quattrobros twincharged audi 90

PostPosted: Wed Dec 18, 2019 1:10 am
by quattrobros
Received my Hella/Behr radiator from the uk today. Not the greatest feeling quality wise but at least it looks alot better than the old one. only half the price of the nissens radiators that can be found online in the us.

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Re: quattrobros twincharged audi 90

PostPosted: Wed May 27, 2020 7:51 pm
by quattrobros
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Re: quattrobros twincharged audi 90

PostPosted: Wed May 27, 2020 10:50 pm
by quattrobros
Finally got the car working. Ended up needing a larger wastegate right off the bat so ditched the stock one and went with a 44mm.

The twincharge system seems to be working as planned. Theres a switch on the dash so it can be ran turbo only or compound twincharged mode.

The supercharger does 9-10 psi on its own (yes i ran it supercharger only and its not that great at that boost level) and the turbo adds enough boost to reach the gate pressure of 15psi. At around 4500 rpm the supercharger turns off shutting the wastegate and making the turbo spool up to 15psi. Transition happens very quickly and is not noticeable.

Basically feels like a v8. Have a d2 s8 as well and thats what this reminds me of so far. No lag and lots of part throttle torque.

Planning to go e85 soon and raise the boost. When the smaller wastegate was in place the compound charging would easily make over 20psi due to overboost before reaching 3000rpms.

Will have some video soon!

Re: quattrobros twincharged audi 90

PostPosted: Thu May 28, 2020 1:52 am
by quattrobros
Here are a few pictures of the switch. In the middle position the car is in turbo only mode. In the top position the ecu gains control over the supercharger clutch and bypass valve. The clutch is set to always be on while the switch is on and the valve closes above 30% throttle up to 4500 RPM routing all turbo air through the supercharger. Once past 4500 RPM clutch turns off and the bypass valve returns to its normally open state allowing the turbo to go straight into the motor. The bottom position of the switch is for launch control.

Other twincharged cars ive seen use a blow off valve or a normally closed throttle body to control supercharger boost. Doing it the way i did prevents the engine choking in the event of a bypass valve failure. Also turbo flutter :)

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Re: quattrobros twincharged audi 90

PostPosted: Fri May 29, 2020 11:18 pm
by PRY4SNO
This is wild stuff, congratulations!

Cannot wait to see some video and hear some of these beastly noises.

Also, >20psi before 3k rpm is insane. Glad you got her dialed in before too long.

This is only going to get better, looking forward to more updates.

Re: quattrobros twincharged audi 90

PostPosted: Thu Jun 11, 2020 11:15 pm
by quattrobros
Here is what i came up with for the dual pump set up. The second pump is activated by a pressure switch at the intake manifold. I was a little paranoid using a pressure switch and a relay as any of those could fail and cause the second pump not to come on. I ended up cutting one of the n75 wires and running it through a relay as well so in the event of anything happening with the fuel pump ill be limited to gate pressure.

Just waiting on some injectors and the flex fuel sensor and its ready for e85!

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Re: quattrobros twincharged audi 90

PostPosted: Wed Jun 17, 2020 1:50 pm
by quattrobros
Woop!

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Re: quattrobros twincharged audi 90

PostPosted: Wed Jun 17, 2020 3:30 pm
by audifreakjim
That fuel pump setup turned out nice!

Re: quattrobros twincharged audi 90

PostPosted: Wed Jun 24, 2020 11:06 pm
by quattrobros
Got it running on 72% ethanol now. I was under the impression i could keep one VE table and use anytrim on vems to adjust fuel based on ethanol content but that seems to not be the case. As i add more and more ethanol my "cruising" zone on the VE table seems to need more fuel compared to my full throttle zones. It seems to specifically be the area where the turbo starts to spool at 102kpa. Its good enough for different concentrations of e85 but i dont think ill be able to go from 93 to e85 without some tweaking.

I also recorded a not so good one handed video to showcase how it sounds. 3rd and 4th gear are only at 30% throttle just enough to close the supercharger valve and have it start building boost. Ill have better video eventually from outside the car at full throttle without the wind noise.


Re: quattrobros twincharged audi 90

PostPosted: Wed Jun 24, 2020 11:31 pm
by jolio1994
God this think sounds wicked. I can't wait to see it running at full tilt!

Re: quattrobros twincharged audi 90

PostPosted: Mon Jun 29, 2020 10:07 am
by audifreakjim
I run ~e45, and mix it to suit at the pump. My main tune is targeted at that mixture with no flexfuel adjustments. My "low boost" tune is flexfuel and it's basically to get me from point A to point B till I can get proper fuel.

Re: quattrobros twincharged audi 90

PostPosted: Mon Jun 29, 2020 12:38 pm
by quattrobros
I thought about doing that also but i want to be able to just use whatever is at the e85 pump and not worry about mixing. Everything seems to scale fine other than the circled zone. I've ruled out possible fuel pump cavitation or any voltage change affecting injector behavior at that point and even my twincharge intercooler piping doing some helmholtz resonator type thing but none of that is happening.

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Everything works and drives fine its just weird to me. If i were to put 93 in it now everything else would adjust but that zone would probably be too rich.

Re: quattrobros twincharged audi 90

PostPosted: Tue Jul 21, 2020 8:24 pm
by quattrobros
Small update:

Had a horrible misfire for a while. Turns out the injector connectors were all broken apart on the inside. Bought new ignition coils in the process of troubleshooting which eventually lead to a trigger error misfire while trying to use the supercharger. Old coils are back in and everything is working amazing now. Car has been on e85 for a few weeks now with no hiccups.

Don't have access to a dyno for ignition tuning but i did get a hold of amdisthebest (Nick) who is currently tweaking the timing for me. The car is starting to feel pretty freaking fast now at only ~18 psi.

Here is a quick picture from some logs i have of the boost curves with the supercharger on and off. There is no boost duty cycle pre 4400 rpm so the compound charging is limited to spring pressure. Once i add some duty cycle in the lower rpms it should make the boost come on even sooner.
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Within the next few weeks it should be all tuned with the boost raised some more.

Re: quattrobros twincharged audi 90

PostPosted: Tue Jul 21, 2020 8:48 pm
by quattrobros
Here's a shot of the car too. The whole US/euro bumper thing went way over my head and had to do a lot of cutting on this s2 fiberglass replica. I was able to get it for $200 so i don't feel too bad about it. Its my only option since the supercharger pulley and intercooler push everything forward so much.

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Re: quattrobros twincharged audi 90

PostPosted: Tue Jul 21, 2020 9:00 pm
by mrdeye
Cool pic. Where’s that bridge at? Or is that a high speed pic going through the Golden Arches drive through? :D :beer:

Re: quattrobros twincharged audi 90

PostPosted: Tue Jul 21, 2020 9:09 pm
by quattrobros
I was thinking the same thing :lol:

Its the Hoan bridge Milwaukee Wi

Re: quattrobros twincharged audi 90

PostPosted: Tue Jul 21, 2020 9:13 pm
by quattrobros
Here's another

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Re: quattrobros twincharged audi 90

PostPosted: Wed Jul 22, 2020 1:33 pm
by PRY4SNO
Tis a brawny thing of beauty. Can't wait for more pics and vids.