O.T. Twice helically wrapped around an inclined plane...

[Randy Forbes]

Okay, this isn't about my Healey (though I did just say Healey in the post...) but since there's a whole sub-set of Healey (there it is again) owners that have either Z3s, Z4s or ///M3 & ///M Coupes or Rdstrs, I thought this might be of interest to them.

For the past couple of weeks, I indulged myself to take time away from other (paying) jobs in the shop and do a performance upgrade on my own 1999 BMW ///M Rdstr. At 94,273 miles, I've gone and supercharged it again__twice before, it was fitted with a Dinan/Vortech Stg1 centrifugal setup (adding about 110 bhp). All along, at least ever since March 2006, when I fitted a new Eurosport Twinscrew supercharger package on a 2000 ///M Coupe, I've wanted to put the same system on my own car. It doesn't drive like a boosted car, it's more akin to having added an additional engine...

A couple of years ago, while already making plans to move from Ohio to Florida, I was commissioned with installing a secondhand Active Autowerke version of the twinscrew, and the girl that he bought his "kit" from approached me to see if I wanted to buy her recently acquired Eurosport version (off a '95 M3, which is an OBD1 car). She wanted a Eurosport Twinscrew on her E-36 M3/4-door, and not finding one, bought the AA version first. Then, upon finding the ES/TS, decided to sell the AA one__okay, getting convoluted now__she then discovered that Eurosport was developing a 2.1 litre (volume of air per revolution) twinscrew package (the previously mentioned units are both 1.7 ltr) and figured she might as well hold out for that (including a full engine rebuild in the process__what a girl!).

Both of Susan28's former twinscrews, as I received them:

Because of moving, being super busy with other people's cars, and the task of sourcing missing pieces, it wasn't until two (2) weeks ago that I pulled the trigger on my own Eurosport Twinscrew Supercharger installation! In two (2) words: HOLY POOP!!

The ES/TS probably adds something in the region of 175 (conservatively) to 225 bhp, on top of the 240 bhp manufacturer's rating (BMW has always been ultra conservative on their ratings too, unlike MOST manufacturers...).

I've only put a few test miles on it so far, but it is certainly as awesome as I remember it! The ES/TS being a little more brutal, though totally linear, in power delivery than the AA/TS (I ALWAYS put at least 100 - 150 miles on any car after I install forced induction__just to make sure the cars are well sorted before their owners get them back__usually 1000 or so miles away).

I have albums in my gallery of each of the builds listed above (as well as several more turbo & supercharger installations):
2000 ///M Coupe: https://www.spcarsplus.com/gallery3/index.php/zts
1998 ///M Rdstr: https://www.spcarsplus.com/gallery3/index.php/ptr-twinscrew This contains embedded albums

And now my own 1999 ///M Rdstr:

Build album here: https://www.spcarsplus.com/gallery3/index.php/TS-prep-work

I still have a few tasks left to do: the injectors, at 42 Lbs/hr, are deemed too large, and I'm sourcing some 37 Lb/hr ones; the fuel pump needs to be swapped out for a 255 Ltr/hr unit, but I'll have to get the fuel level below 1/8th tank before I can do that. I still want to put my Innovate LM1 wideband O2 analyzer on it, as well as log data with the Autologics diagnostic computer, and then see what the software needs in the way of final tuning. Ultimately, I want to get it on a specialists dyno down near Miami, so the hardware/software can all be maximized.

You can make ultimately higher horsepower and torque numbers with custom turbocharger installations, but for everyday drivability, the twinscrew is very hard to beat. I'm one happy guy

 

[HealeyRick]

Very nice, Randy. Always been a big fan of the M Roadsters since they were introduced, and yes, even the "Clown Shoe". 400 hp + must be a blast. Any reinforcement needed around the rear axle for this mod?

 

[Randy Forbes]

Very nice, Randy. Always been a big fan of the M Roadsters since they were introduced, and yes, even the "Clown Shoe". 400 hp + must be a blast. Any reinforcement needed around the rear axle for this mod?

Do you not know who you're talking to? I AM the go to guy for this work; enough so that it enabled me to leave my day job behind

But to directly answer your question, yes, as I'm sure that an unreinforced trunkfloor/differential mount would suffer in short order, especially if the power was being exploited.

For the record, this car LC89268, was repaired/reinforced by my then local BMW dealership's bodyshop back in the summer of 2004. It took long enough for BMWNA to make a determination as to whether they'd warranty it (this was a CPO car, with a 6-yr warranty period__the other one we bought new, so only 4-yr warranty) that I went ahead and made a plan to reinforce it myself. Long story short(er) the dealer installed the parts I made (under warranty) and therefore, I took that as an unofficial endorsement that I was on the right track with my design. A month later, I took the 01, LJ80510, in for the same/similar repair-reinforcement, and the tech asked me if I wanted to do anything different, and that's when the dual ear reinforcement was likewise officially installed (granting me another unofficial endorsement).

Do a search sometime on "Randy Forbes BMW" and you'll see what I mean

 

[DerekJ]

Great work Randy. So glad you went in this direction as opposed to buying a Toyota Prius!

 

[HealeyRick]

Do a search sometime on "Randy Forbes BMW" and you'll see what I mean

Very impressive "a Z3 guru". And I thought you were only a Healey guru That the Z3 needed "customer product development" like yours is more worthy of BMC than BMW.