Got my Birkin!

[jloehlein]

Wanted to take a minute and introduce myself. I bought the Supercharged 2009 Birkin on BringATrailer about a month ago. I've been lusting after a Lotus 7 replica for almost 10 years now. I bought my first Miata about 5 years ago (for $200!) to build one, but after determining I didn't have the time, my friends and I turned it into a crapcan race car and ran it in Chump Car and 24 Hours of Lemons.

 

The plan has always been to build one, but that hasn't stopped me from trolling the internet looking at the ones for sale. When the Birkin came up on BringATrailer, I was talking to a friend about it. I'm not sure I'd ever spend that much money on a car, but it looked pretty sweet. He offered to split the car with me and after some discussions about logistics, we agreed we could work it out. So we bid and won...

 

After waiting about a month, the truck showed up last Sunday. Very exciting. I figured I would chronicle my ownership experiences here.

 

 

We unloaded it and looked it over. Overall, it's fairly cleanly built.

 

 

 

We drove it around for a bit, taking a bunch of the neighborhood kids for rides around the block and then went on ~30 mile drive. The car is pretty quick and rides better than I expected. It's easy to drive over 50% or under like 1%, but very sensitive to throttle changes. We noticed a few things that we're digging into now:

 

• the oil pressure gauge only reads about 30-35psi once warmed up when driving around over 2500rpm. i'm hoping it's just the gauge because there is another gauge on the accusump. we shut the accusump off mid-drive and that gauge read either 60 or 80psi when we checked it (it's in the front grille). we just put one of my spare gauges and senders in it to verify, but haven't fired it back up yet.
  
• many exhaust leaks - every exhaust gasket was blown out. the manifold gasket, the gasket between the collector and cat, and even the slip joints at the collector were leaking. Easy fix, we ordered some new gaskets and are planning on trying some "Muffler and Tailpipe Putty" or just some copper RTV on the slip joint for now.
  
• the car runs insanely rich. i think this is contributing to how difficult the car is to drive at part throttle. you can smell the gas and see black soot on many things around the exhaust outlet. the plugs are also black and were very wet when we pulled them (pic below). there is no wideband O2 giving feedback to the ECU, so I assume it's running of the base map in the tune. we pulled a spare wideband I had laying around and are installing it (once we fix all the exhaust leaks). the ECU is a Specialist Components Typhoon. There is a serial cable dangling out of it. I bought a serial to USB adapter and will see if I can access the tune with that.
  

 

 

 

Anyways, the car is sitting for now while we wait for some parts. Progress will be slow over the next month - I am close to finishing a Factory Five Cobra build for my Dad. We're trying to do the Hot Rod Power Tour in June and need to have the car on the road by then. I'm looking forward to interacting with the community here.

[jloehlein]

Well, unrelated to the Birkin, but exciting to me...I painted my Dad's Cobra over the weekend! The color is Lexus Matador Red Mica. My Dad is wet sanding the whole thing and I've gotta spend the next weekend or two buffing before we unmask everything and can do the final assembly (windshield, wipers, lights, etc).

 

 

In the meantime, Jeff re-installed the exhaust on the Birkin with new gaskets. We've gotta figure out where we want to drill the hole to run the wideband O2 into the passenger footbox and then hopefully we can fire it up and start tuning...in a couple weeks.

[mrmustang]

Any pictures of the Birkin engine compartment, I requested several from the seller (way before it was on BAT as well as on BAT) but never received any.

 

Also, nice FPSB , is it a MK I, II, II.5, III, III.1, or a new MK IV (I've built "just a few")?

What drivetrain, suspension you went with?

 

 

Bill S.

[jloehlein]

I've just got the images that were part of the auction. If there is anything specific you're looking for, let me know.

 

The Cobra is a MkIV. It's got a 408w and Tremec TKO600. 3-link rear end. I go carted it at a couple autocrosses last year with some 12 year old street tires and it was fun. Hoping to get it looking like a car in the next two weeks so we can kick off the registration process.

 

[Automoda]

That cobra is going to look great. Its one of the most beautiful car shapes, in my opinion. Color sanding will probably take more than a couple weekends. With some brands of clearcoat you need to get it done within a time window, and you need to get the room as warm as possible to keep the paint soft.

 

Regarding your exhaust leaks. I used some black tar-like stuff on the collector and it worked well. For a while. I think the tar stuff has dried up and vibrated enough that some exhaust is leaking out again. I'm seeing some odd readings on my O2 sensor which is a few inches down the pipe. I think a little air is getting sucked in from time to time. But you don't run these cars in closed loop anyhow so the 02 sensor is only used for tuning. Honestly I should remove it and put a plug in the pipe when I get it tuned right. Mine runs rich too, but I'm reprogramming it from scratch and its nowhere near done. Really its probably worth it to go to a pro tuner with a rolling road.

[jloehlein]

Any pictures of the Birkin engine compartment, I requested several from the seller (way before it was on BAT as well as on BAT) but never received any.

 

Also, nice FPSB , is it a MK I, II, II.5, III, III.1, or a new MK IV (I've built "just a few")?

What drivetrain, suspension you went with?

 

I only have what was on the listing and linked in the post on this site. Are you looking for something specific?

 

The Cobra is a MkIV. It's got a 408w, Tremec TKO600, and 3-link rear end. I put some 3.08 gears in there to calm it down a bit. Just using the Konis and springs that came with the kit.

 

 

That cobra is going to look great. Its one of the most beautiful car shapes, in my opinion. Color sanding will probably take more than a couple weekends. With some brands of clearcoat you need to get it done within a time window, and you need to get the room as warm as possible to keep the paint soft.

 

Regarding your exhaust leaks. I used some black tar-like stuff on the collector and it worked well. For a while. I think the tar stuff has dried up and vibrated enough that some exhaust is leaking out again. I'm seeing some odd readings on my O2 sensor which is a few inches down the pipe. I think a little air is getting sucked in from time to time. But you don't run these cars in closed loop anyhow so the 02 sensor is only used for tuning. Honestly I should remove it and put a plug in the pipe when I get it tuned right. Mine runs rich too, but I'm reprogramming it from scratch and its nowhere near done. Really its probably worth it to go to a pro tuner with a rolling road.

 

Thanks. We'll see how long this stuff lasts on the exhaust. I'm hoping to get the tune pretty close on the street - might then spend some time dyno tuning. Might do the Cobra and Birkin together.

 

Re: wetsanding, thankfully my Dad is mostly retired, so that's pretty much done already and I've just gotta polish everything now. We're pretty close - very exciting after ~2 years.

[mrmustang]

I wanted shots of the supercharger set up, that is all

'

 

As for the MK IV (the best of them all), the 3 link is the way to go, I've retrofitted them in to 6 of my early FFR's that were built without them. Makes the car superbly predictable at track speeds as well as on the street. Koni's are the best shocks FFR has ever offered............200hp is enough to kill you, so best to respect the car before you ever turn the key for the first start, as the car is like nothing you have ever driven in your life, and the learning curve while not long, can be dangerous. Just some friendly advice from the retired body shop owner (and racer) who has repaired enough of them from owners who "knew what they were doing".

 

Bill S

[papak]

The exhaust on my Birkin has the O2 sensor mounted midway between the 2 into 1 merge and the muffler flange. I used the orange sealant on all mating surfaces except the slip joints. I plan on wrapping those shortly. The basic programming in the Typhoon ECU adds a longer pulse width under acceleration and feathers it off after you have reached a steady throttle setting. Hence, if you are running rich enough at cruise, you will always run richer under acceleration. Tom Carlin said to try to run a lambda level of .94/.95. Better a bit rich than lean. Get it running as would like with the closed loop disengaged and then activate it. the closed loop has a range of authority of 20% or so. Don't forget to calibrate the sensor first.

[jloehlein]

Here are a few shots of the nose of the car and the front of the motor. The supercharger is really buried in there, kind of difficult to see anything. The intake from the filter makes a 90 degree turn into the supercharger inlet through the sheet metal brace that has a few holes punched in it. As it comes out of the supercharger, you can clearly see the BOV and it just runs into the throttle body.

 

 

 

 

We also noticed that the hose to the Accusump is leaking from the back of one of the fittings, so I'm ordering more hose and replacing it.

[Lightguy]

I was this close to buying that car but kinda felt a bidding war was going to happen.

Wasn't ready yet anyhow.

One would think the "supertuner" that put the supercharger on would have sorted out the glitches as was led to believe in the ad.

Looking at the photos first thing I would do is somehow get cool air to the air cleaner.

Once the hood is on you get hot air through the radiator.

East cheap HP and mpg.

Looks like a nice car otherwise.

[jloehlein]

Well, good news on a number of fronts.

 

1) I basically finished my Dad's Cobra. It's at his house now, waiting for the DMV inspector to come bring the VIN tag. Then we can drive it around, tune it, and button up any loose ends.

 

 

2) We put a spare oil pressure gauge on the Birkin and it shows ~60psi at 3k rpm, a lot better than the 35 the VDO gauge showed. I don't trust any of the VDO gauges in the car - the odometer blinks in and out, the tach gets stuck occasionally, the voltmeter reads 12v all the time, and the coolant temp reads over 220 when the ECU is seeing 180. Oh well, at least I know I have good oil pressure.

 

3) I started re-tuning the car from scratch and with ~2hrs work so far, the car runs way better. AFRs under acceleration are 11.5-12.5 and 13-14 cruising around. The hesitation and jerkiness is all gone. I suspect that after the supercharger was put on, the fuel curve was still the same shape as when the car had ITBs - and there is a big difference between 5% throttle opening across (4) ~50mm throttle bodies vs a single ~65mm throttle body. I switched the ECU to speed density and used the fuel table shape from a 2.0L Honda motor (K20). Once I dialed in the idle, we drove it around a bit and I tweaked everything under 5k rpm, staying out of boost. We're setting up dyno time over the next couple weeks to really tune it. I'm excited to see what it'll do.

 

4) I was trying to figure out how to use all this newly found free time (I've been busting my @ss on my Dad's car for the last 6 months to get it done), so we threw the Birkin on the scales. 1310lbs with 3/4 tank of gas. Not too bad. Balance is not terrible with a driver (2nd pic).

 

 

 

Next steps are dyno tuning, corner weighting, and alignment. Anyone have any track-oriented alignment specs handy I can use as a starting point?

Edited June 4, 2017 by jloehlein

[jloehlein]

Alright, took the car down to the dyno today. The Typhoon ECU and SXTune software are fairly clunky, but we got a safe tune on it. I've gotta go back through the logs, but it seems like it's making about 5psi or boost at 4500rpm and 12psi at almost 7k. The car ended up putting down 245hp and 191ft-lbs. We only wound the car out to ~6800rpm for now. I'm going to take care of a few things and we'll head back to the dyno to do some more tuning later.

 

 

. Edited June 11, 2017 by jloehlein

[panamericano]

Congratulations on the new Birkin. Not to start a gang war, but I love telling people that of all the companies Caterham sued, Birkin was the only case Caterham lost. Looks great.

[jloehlein]

Finally got the car running what I will consider 100%. The throttle was still pretty sensitive, so I stole a throttle cam off a spare Porsche 944 throttle body my friend had lying around. We used a Miata throttle cable to get it to work.

 

 

Oh, and I also swapped in a Microsquirt ECU. That involved digging the engine harness out of the car. The Microsquirt and Typhoon use the same connector, so most of the work was just labeling wires and then pulling them out of the connector and moving them to a new location.

 

 

 

With the Microsquirt in, we spent a bunch of time tuning and brought it back to the dyno. Between that and the throttle cam the car is much smoother to drive. Took it to a test and tune autocross today and dominated everything with fenders. Unfortunately, I didn't bring my GoPro, but it was a blast. Here are the final dyno numbers. I suspect it's got stage 3 cams in it (torque peak is like 6800rpm) and the car would be faster with a cam that traded off peak power for more mid-range. Whatever though - it's plenty fast.

 

 

Now we just need to build another, taller roll cage so I can drive it on track. If anyone wants to buy the Typhoon or existing roll cage, shoot me a note!

Edited October 8, 2017 by jloehlein