REATTA FACTORY TURBO

[reattadudes]

just received a recent ebay purchase today, a 1989-issue Buick press kit (dated 1/20/89) all about the 1989 Reatta Turbo. very interesting!

some basic information: (from the press release) "the turbo Reatta is powered by a hand-built 3.8 litre V-6 rated at 245 horsepower and 300 foot/lb. of torque. the 3.80 inch bore and 3.40 inch stroke (front wheel drive model) is fitted with off-the-shelf Grand National crankshaft, rods, and roller-lifter camshaft."

some other interesting facts: modified 440-T-4 transmission, shift points at 4800 RPM, blocked part throttle port allows overdrive to stay locked in at wide open throttle. 3.73 axle ratio. two-piece alloy wheels with Goodyear 245-50 ZR16 tires, beefed up suspension. the front end features three air intakes (no grille or fog lights; the former fog light openings are now round) the center opening improves air flow to the radiator, and the left and right side openings direct cool air to the front brakes and air cleaner.instrumentation has been modified to include a digital speedometer that reads to 199MPH, and a CRT that displays turbo boost both digitally and graphically.

0-60: 5.7 seconds!! 16 pounds of boost, top speed 150MPH

the press kit also came with some very nice black and white photos, and some color slides. wonder what became of this car? maybe it will surface sometime.

the car looks very purposeful, and the suspension looks lowered as well. even though 16 inch wheels are quite common now, back in '89 there weren't too many cars that had them. wonder why they didn't put this one in production? probably would have blown the white patent leather right off of Roger Smith's shoes.

Mike

[Guest]

Wow would be VERY nice to get some specs on it, and possible find out what happened to it. I would sell my red one in a heart beat for that!

[twistedmooch]

i would sell my soul to have such a reatta lol, i cant believe its 2x as fast as a normal reatta

[padgett]

Musta cut back on the speedo - had Greg's reading 255 mph in first gear.

155 with 3.73 would work out to 5600 rpm in o/d, no wonder it was enabled. Did it have any aerodymanic enhancements ?

Wonder if it was actually built.

[reattadudes]

Padgett,

I'm looking at the photos, and there are not really any aerodynamic enhancements. the front end looks much better without the grille, and the round openings where the fog lights had been is also an improvement.

it is certainly an actual car; one of the photos has a 'fifth wheel" behind the car. there is also a photo of the engine compartment, as well as five color slides.

the press release is four pages long; I didn't want to take up too much space here writing the entire thing, but here is another interesting quote:

"while the turbocharger mounts in a conventional position, it is not a stock Grand National unit. Garrett supplied the special T-25 high-response assembly which is liquid cooled and oil-lubricated. a stock Grand National mass air flow sensor and sequential-port fuel injection system are employed. free breathing is ensured by the use of 2 1/2 inch exhaust pipes in concert with a 1987 Grand National muffler and stock Reatta catalytic converter.

installing the turbocharged engine in the Reatta required only minimal modifications, mainly the trimming of some edges for turbo and component part clearance. with the engine in place, the underhood enviornment looks production stock."

I don't have a scanner, and wouldn't know to use it if I did. however, I will try to get a friend to scan these next week, and get them posted. they are quite interesting, and the engine bay photo is worth a thousand words.

this is about the best $14.95 I've ever spent! <img src="http://www.aaca.org/ubbthreads/images/graemlins/smile.gif" alt="" />

Mike

[padgett]

Agree the Reatta looks and breathes better without the grille. Before everyone removes theirs, keep in mind that the purpose of a grill is to keep objects from striking the a/c unit at road speed. Would think that a flat black eggcrate mesh to replace the grille might be appropriate/attractive.

[poncho]

By all means, PLEASE post some pictures! Sounds like a must-see!

[reattadudes]

will have pictures posted on our web site by thursday. will post here when they are available.

Mike

[2seater]

Was there any mention of the other two prototype Reattas? If memory serves, there were three different ones, a high boost (sounds like this one), a low boost and a rwd version. Supposedly the high boost was destroyed when a journalist crashed it during testing. Info like this is of great interest.

[reattadudes]

Hal,

there was some mention in the specs of a lower boost version, but there was no differentiation in the photos of one from another. I suspect that they had an identical appearance. no mention was made of a RWD version in the press release, but I have heard mention of this by others who had seen the car here in arizona, both at the mesa proving grounds and at firebird raceway. Phil Hertell from Speedway Automotive had talked to us at great length about seeing several RWD versions at firebird raceway.

its rather ironic that the Grand National was gone by the time this car was out, and I'm sure there was much disappointment by many in the Buick division when this ball was dropped. what a "halo car" this would have been for Buick...as far as performance goes, it would still be competitive today.

due to the many emails I have received about this press release, we will be posting all the black and white photos and text in its entirety later this week. will try to figure out how to post the color slides as well. we will have a link to our web site posted when they are ready.

thanks to everyone for their interest.

Mike

[padgett]

Well the 89 turbo 3800 RWD Trans Am is still the fastest built so you know the turbo project was alive at that point but I suspect the motorheads were concentrating on superchargers by then.

Speaking of which, does anyone know if the 89 TA used a C3 cor a P4 computer ? If a P4 that would be a good place to start for a Turbo Reatta project, all you would need is to convert the data stream to match the BCM.

If they put the boost on the CRT that is exactly the type of thing that would be easy if we ever get the BCM program decoded.

[Guest Greg Ross]

Padgett,

met several of the Reatta engineers in Flint and was given a name for a fellow (since retired)who handled tweeking/ tuning/ detuning. And one gent told me "you should have seen the "Police Version" he was working on"?!?!

I'm going to get off vacation here one of these days and will proceed to try and track this guy down.

The GM HVAC Eng. from thr Reatta Program has a Reatta ('90 I think it was) and was telling me the folks left around GM from that era had him convinced you could not transplant an S/C in a Reatta.

He was very very intrigued to see Betsy Blue running the way she did on stock components.

[Barney Eaton]

Car & Driver covered these cars in their July 1989 issue. The article was titled "Crystal-Ball Buicks" and I just happened to have an issue in front of me.

* Rear drive turbo Reatta 245hp 3900# 0-60=7.0, top spd=140

* Front drive hi-boost Reatta 245hp 3800# 0-60=5.8, top spd=150

* Front drive lo-boost Reatta 230hp 3400# 0-60=8.0, top spd =140

* Front drive supercharged Regal 230hp 3200# 0-60=8.0 top spd=130

* Rear drive turbo Regal 245hp 3400# 0-60=6.5, top spd=140

* Electra Estate Wagon,turbo V6 328hp 4300# 0-60=5.2, top spd=120

That Electra wagon is the real sleeper.......it apparantly had the GNX engine.

This article did not list the final drive ratio of any of the cars.

[padgett]

Have to wonder a bit about magazine tests. In 1967 the brand new Quadrajet 400 was matched against a 66 Tripower 389. Trips flowed more air but the currently marketted one won.

Seems like the general would have a vested interest in the FWD version being "faster".

[2seater]

I have asked about the computer also and the general opinion it was the older C3, as it used similar replaceable chips like the GN's. No really definite answer to that one though and would be greatly interested if there is a turbo compatible computer out their for my application. As an update to my project, the data recording device failed to be able to record real time data that would be of any use to me and has been sent back for a refund. I have ordered an alcohol injection system to see if I can get the knock under control. Kind of a bandaid if it does work, but turbo specific programming has come up empty after several false leads. Interstingly, the system I ordered is calibrated to a s/c car as the boost levels I have targeted are similar to the supercharged cars rather than the higher boost the GN's operate with. We shall see.

One thing I noticed about the initial article on the turbo Reatta is the reference to the GN roller cam. The roller cam was introduced in the 3800 and did not come from the GN which used a standard non-roller lifter. Picking nits I guess. <img src="http://www.aaca.org/ubbthreads/images/graemlins/grin.gif" alt="" />

[padgett]

Well if I had a week, a car, and a dyno, coming up with a PROM would not be too difficult. Would use an L-67 ECM and PROM as base for the data points and maps and a blend of the L-67 programming with the "C" data stream so that the CRT would work. This would allow development of the proper boost/retard and gm/sec to 255 maps.

Is one big difference in most aftermarket turbos I have seen compared to the supercharged L-67 - the '67 sucks and the turbos blow (through the throttle plate). To me a draw-through so the MAF is seeing unheated/un presurized air flow is much more efficient. If the turbo is upstream of the throttle plate, not only is lag more pronounced and the initial airstream much hotter but the MAF has a much more difficult time of sensing air flow. This difference is one reason the supercharged PROMs require more diddling for a turbo - boost is boost but the side of the throttle plate it is developed on makes a big difference in programming.

However it is unlikly that any of the three will be available in the near future so a lot of my theory has to remain that. For now.

Don't let me stop anyone from trying, am just pointing out the areas that will need work. In any event, the L-67 electronics are a good place to start.

Where is the throttle plate in the pictures ? Every GM production installation I've seen starting with the Corvair Spyder and the 215/215 aluminum V-8 of the early 60's has been draw-through. There is a reason.

[2seater]

I agree there is some merit to pulling air through the MAF, as the temperature compensation problem would go away, and it may also have some benefit from a more laminar air flow. It is impossible to tell how the air stream from the turbo is actually aimed at the MAF screen since there is a very small distance between the outlet from the compressor and the MAF. Now that I have relocated the air filter, there is more room to try relocating the MAF to the inlet side of the compressor and it will be a winter project. My only concern is my initial one, the passages in the MAF are relatively small and uses an indirect method of calculating air flow, and it is easier to blow through that restriction than pull through it. Most of the old turbo setups were carbed units, and it was easiest to keep the carb at atmospheric pressure so the fuel pressure wouldn't need adjustment. Turbo lag was generally a problem too. The original conjecture of placing the throttle ahead of the compressor, so the compressor spins in a partial vacuum, probably has some merit in that it would spool quicker, however, since there would be vacuum at the compressor it would have little to compress, so lag would be present until air flow filled the compressor with useable air. Only experimenting would answer that question, but my gut feel is that it would be slower to respond to throttle input, going up and coming down.

[padgett]

Biggest concern with putting the relatively small "C" MAF (1991-on "Snakes" intake has a 40% larger throttle body) would be going sonic.

This can occur when the pressure differential across the throttle plate hits 12.7ish psi (ambient is 14.49 at sea level) and can result in choked flow (transonic flow has some interesting math to it, needless to say it ain't laminar unless you can create a convergent/divergant nozzle - adds a bit of complexity to vectored thrust jet engines - did I mention I put in some time at the Swamp as Pratt & Whitney Gov Prod Div in South Florida ? )

Normally this is not a problem until you start boosting an engine though "carburetor icing" is a distant cousin however GM used to limit the boost on early turbos this way - why the Corvair Spyder had a one-barrel Carter - lots cheaper than a waste gate & built in rev limiter.

Now any turbo can result in some lag but they do not have to "spool up" with a draw through, are already up to speed, however filling the plenium can take a moment reguardless - is why a manifold designed for boost does not have a plenium as such.

That plenium lag is going to be there with any system. Is not necessarily bad, sudden changes are to be avoided on the race track, going "up in smoke" is not the fast way around, a steady build of power over about a half second is really better than all in at once. Things also live longer.

Even the "C" engine has a plenium about the same size as a '57 Rochester unit, probably was inspired by the same calculations, the Rochester was mechanical and was constant flow instead of pulsed but the air don't care. Snakes is worse.

For minimum lag, I'd consider starting with a "C" manifold and reducing the plenium size with some epoxy but that would be a later experiment.

[Reatta]

so you want HP with turbo?

[Guest Buick Mike]

This one is better. Turn up your sound.

http://www.fasttrackperformance.com/page5/chow%20movie%20files/christtgn.wmv

Mike

[Guest]

Aiming for slightly lower hp than that GN. <img src="http://www.aaca.org/ubbthreads/images/graemlins/tongue.gif" alt="" /> Nah, that GN is awesome, but I wouldnt wanna drive it around the street, especially with no filtration on the turbos.

[Guest EDBS0]

1076.7 HP and it smoked the tires on the dyno <img src="http://www.aaca.org/ubbthreads/images/graemlins/shocked.gif" alt="" />

[2seater]

Ahhh, the lack of plenum to fill makes sense. I have one of those old carbed turbo manifolds from a 3.8 Riviera and now I understand why it is shaped that way, thanks. The GN's and Turbo Regals do use a plenum, but they are designed as a blow through from the start, and it (and ours) do look reminiscent of the Rochester. I know the GN guys have struggled with even air flow to all cylinders and they used to increase the volume of the plenum but the latest way is to actually partially block some of the flow to the cylinders that run lean, so they are less prone to detonation. I do appreciate the conjecture of reducing the volume somewhat and I have been thinking about how to add an insert attached to the adapter between the throttle body and the actual manifold. It would then be possible to experiment with varying the air outlets from the insert into the manifold, to help balance the flow. Another good winter project. I get lost in the theoretical calculations mentioned, and will have to use the old emperical cut and try <img src="http://www.aaca.org/ubbthreads/images/graemlins/grin.gif" alt="" /> My throttle body has already been enlarged and a new plate installed but there isn't enough "meat" to get it as large as the later model. It will have to do for now and seems to work well for the boost levels I am using. As always, I appreciate any input.