1988 All Wheel Drive Twin Turbo Experimental Car EX-5115

[3X00-Modified]

I guess it's time I create a thread about this car to document it on here as well as follow any updates that I may do to it... that means I need to take pictures of when I take it apart more... JOY... lol

Story about the car...

So lets keep a long story short. GM was forced to sell most of its heritage museum collection and the AWD Twin Turbo Beretta test car was one of them. Unfortunately, no one in the club at the time of the sale was in any position to buy it. It sold in 2008 for $8500. No one saw it again till it surfaced on eBay in 2010 for 10k, located in CT on top of it. SO, I went for a ride to go visit the individual. I got a chance to see the car, document some things, take a ton of photos and hear it run. That was that until 2018 rolled around and the Feretta was making headlines again.

When I saw a member obtain the Feretta, and others start to ask about the AWD TT car, I decided since I knew were it once was, that I should research it. I was now able to purchase this car and luckily the original Barrett Jackson buyer still had it. Emails were sent and we agreed upon a price. I went and picked it up the next day. The nice thing about buying the car from a used car dealer/collector, he was able to re-write the bill of sale to have the actual vin number that was noted on the door and under the carpet, this allowed me to register the vehicle as a 1988 Beretta CL 2.8L v6 car. On to the back story about the car, as found in HotRod Magazine June 1998 Edition.



Since buying this car I have found a few items that needed to be replaced or serviced since it’s been sitting so long… Lets start with the fuel system. Luckily the tank and everything else was in good condition and working order, the injectors on the other hand… those needed to be fully replaced. Being so old, one failed shut and another was stuck open. Car ran, but not well at all. I did get the car running and driving for Bfest 2018, but unfortunately the turbos were not up to snuff to perform the way they should. They are variable vane turbos and the rear one the vane system is stuck in the quick spool location. They are supposed to transition to allow more flow as the boost rises but the actuator was stuck. That’s a project for the future when I really dig into it.

Items replaced so far, fuel injectors, water pump, motor mounts, brake pads, rotors, rebuilt calipers and master cylinder. I’m sure as time goes on, I’ll find more that needs to be replaced and fixed, and hopefully when I do, I’m able to find parts for it.

Final plans for the car, Full drive-line tear down and restoration to how it was when they were last testing it. I don’t plan on upgrading anything other than getting many items cleaned up and powder coated. This car will stay as original as it was when GM had it in their heritage collection.

Updated list of things I have modified or changed since getting it.

Rebuilt all brake calipers
replaced all brake pad
replaced all rotors
replaced fuel filter
replaced water pump
replaced all engine mounts
replaced fuel injector since 2 were dead
replaced braided fuel lines due to leaking/vapor issues
tore down, cleaned up and rebuilt brake master (can't find seals to replace, application unknown)
Installed Moates chip adapter and created new bin/chip to idle better, lowered MAF tables.
welded in O2 sensor bung so I can monitor O2 with wideband, No narrow band used at all.
replaced Battery
replaced missing VIN tag under windshield

Uploading all pics I have to main site to insert here.

More to come.

[Rettax3]

Thank you Jon. While part of me is envious about this car, I honestly can't see anyone (including myself) that is better suited to own this part of GM and Beretta history. I appreciate the work you do on these cars, and I am looking forward to seeing more as you continue to work on it.

[3X00-Modified]

Thanks, I hope to get some time to get more info up here with everything I've done so far... mostly just drive-ability changes right now... I hope to dig in further, but I'm so far behind on other projects right now I can't justify starting this one yet.

[3X00-Modified]

Well yeah I should update this huh... Pics and story to come.

[3X00-Modified]

So to start things off I decided to look into the TT's whereabouts when everyone was asking about it on the facebook group, which only happened after Tyler got his hands on the Feretta. Seeing as how I knew where the car last was, and I had seen it with my own eyes I decided to reach out to that individual and see if he was still interested in selling the car. Two emails later I was I was driving to Ross Motor Cars in Torrington CT.

My first sighting of the car since I saw it 10yrs ago.

Car had sat for that entire time... When I saw it in 2011 ODO reading, 7471 From what I can read, bad angle.

And shortly after I got it road worthy... yes I know I did not take a ODO pic when picking it up... So at the most the previous owner drove it 30-40 miles since I saw it in 2010.

[3X00-Modified]

Here is my first looks at the car when I got it on the lift.

No special order here...

[3X00-Modified]

Now came the issues...
Bad Motor mounts,
Clogged Injectors,
Leaking Water pump,
Leaking calipers,
Leaking Master Cylinder,
Dry rotted brake lines,
Dry rotted tires,
Bad upper spring mounts,
I think that's about it...

First things first was to get the brakes all set, so I figured out it has HD A-body front calipers and Fiero, or Pointiac 6000 rear calipers. I ordered up the various rebuild kits and rotors to fix everything that was on there. The rear pads were soaked with brake fluid and it was leaking from everywhere back there. I did some quick seals on the fronts, and rear calipers and set it up to bring to my house since it was being stored at my father in-laws for the mean time.

Found something interesting and learned how they adapted the A-Body knuckle to the Beretta strut... The just cut the top off and welded these together!!!

Same welding marks where the ball joint mount goes... Yikes.

It was then onto the Motor mounts and water pump. No pics of the pump replacement... but it's a basic 3.1L setup.

Found out they were using a MAF on this setup vs speed density.

And the Twins in all their Glory while doing the 5-speed top mount.

Once this was all done I transported it home, and gave it it's first bath in I think 10yrs...

[3X00-Modified]

Now the fun began... Pull injectors and send out for cleaning, fully repair brake system including replace lines and rotors, also re-build the rear calipers again because I missed something the first time around (they were leaking again), as well as pull apart the master cylinder for cleaning and documenting. Still have not found what this is from... closest I found was a Isuzu truck, but the one I bought was much larger than this version.

Their highly customized brake booster.

[3X00-Modified]

More to come... time to take a break.

[woody90gtz]

Cool to see these details. Did they offset the brake booster?

[3X00-Modified]

Changed the angle of it to point more up, (sorry that's hard to tell it's a side profile picture of the booster mods) and it's also not a stock type booster at all. They welded the factory bracket to whatever this unit is.

[3X00-Modified]

Now we get into the motor some... Fuel Injectors were junk, needed to send them out for cleaning which ended up in replacing the whole lot with a newer type of more reliable injector. 2 were dead, one open and one closed. Thankfully he was able to flow test them and figure out what they were for replacement sake. Oh and the pistons have valve relief cuts in them...

Crane gold roller rockers.

Crane Rockers

Valve reliefs.

Valve Reliefs

Clearly some port work done to the runners... That's not stock casting.

Ported

Numbers I found on the underside of the air to water intercooler.

Fuel Rail

Customized fuel rail for AN lines.

Intercooler numbers

New Injector installed

Air Filter housing

Their custom air filter location, and filter

New Injectors

Custom air filter

And the mess of vacuum lines under the intake. Notice the Holley jets that they used to bleed off boost for control... yikes... this will be interesting to iron out after I get the turbos refreshed.

Vacuum line mess

[3X00-Modified]

Since doing most of this work I also had to modify the tune on the ECU. I was able to use a Moats adapter to put their chip off to the side, read the details and modify the MAF tables at idle to help it run better. Something else that I noticed is this car doesn't have an O2 sensor. They had the BLM's locked and weren't even monitoring it with a wideband... that's just nuts. I installed a bung and put a wideband on it so I could see how it was running, that is how I found that idle was super rich. And with the Moates real-time adapter I was able to make changes while it was running and see it's reaction to it, vs burning chip after chip... insane how that's possible with an 88 Corvette ECU, but not OBDII yet...

Added O2 sensor bung on downpipe.

O2 Bung

Corvette Ecu

Corvette ECU

Moates Hardware used.

Moates station

[3X00-Modified]

Just as a heads up, I have not "touched" the car teardown wise at all since it's been in Brooklyn. I have had way too many projects going on. The next major thing on my list is to get the fuel tank down and cleaned out, pumps checked and siphon checked since it's a saddle bag tank, unlike a factory Beretta one. I tried to pump all the gas out of it recently since it's not being used much and the gauge is registering 1/4 yet I am getting air from the pump... and you can hear it sucking down to nothing. I'm not sure if it's pulling fuel from the right side of the tank or not and I'd like to figure that system out and get it all sorted... and then it will be filled up with Sunoco GTX280 98 octane unleaded race fuel to prevent regular gas from causing issue in the future since it doesn't get driven much. It was noted to only be run on Idolene 30 at GM which is an additive free testing fuel that they use. While doing that I also need to get the turbos out to go through them. They are an interesting setup, they have both an Internal wastegate, as well as variable vane geometry on the turbine side. Sadly one of the turbos VNT systems is stuck, the actuator wont move. I'm sure it's from years of starting and moving and not letting it get up to temp. I hope it's repairable, if not Garrett will be getting a call for some custom work since they made these.... Info on VNT Turbos... https://paultan.org/2006/08/16/how-does ... etry-work/ I don't know how in the F they had these in 1988... but they did.

Tag on turbo CHRA

Turbo Tag

Internal Waste Gate arm, Silver tab in center of photo, the diaphragm pictured is for the wastegate.

Internal gate

VNT actuator arm.

VNT System

Dual vacuum diaphragms, one for vanes and other for gate.

Dual actuators

[3X00-Modified]

Wow this shows up all fucky on tapatalk... Photos are not Inline with the post.

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