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Unique 1992 6-Speed Polo Green Convertible, 650HP


Active member
Jul 19, 2004
1992 Supercharged LT1 Polo Green

Time to sell this very unique car. I have owned it since July 2004 and I am very sorry to see it go.

Price Revised March 31 - $15,500 or sensible offers.

61,000 miles on the Chassis, only 3,000 miles on the engine and supercharger.

This is a 6-speed convertible with a fully built and internally balanced, forged LTx 383 motor built by Grimes Machine of Alpharetta Georgia. Garry Grimes is a very respected builder and has many good references (right now I have 3 of his chevy engines in various cars). The engine is built for around 9:1 compression.

The heads and intake are fully CNC'ed LT4 parts. Cam is 236/242 .579/.584 lift on a 114 LSA. The engine has 1.6 Roller rockers.

The supercharger is a very large Vortech V7-YSi capable of 1100 BHP. It currently has a pretty large pulley installed that sizes the boost to around 16 psi at 6400RPM. The entire supercharger setup was built in conjunction with Greg Carroll at Blowerworks, and to the best of my knowledge is one of only two like it. There are YSi blowers running on L98's and Camaro's, but quite challenging to get them to fit under the stock hood of a C4 LTx Corvette. We got a very slick install and it gets a huge amount of attention at shows.

Fuel-wise, it currently has 60pound injectors and dual inline fuel pumps (the big one is an aeromotive), using a racetronix custom harness to supply 14 volts to the pumps.. and I have tested on the car at 88 gallons per hour.

On the dyno with a conservative tune (around 11.8:1 AFR) the car puts 580 to the wheels at 6000RPM, at which point the injector duty cycle is at 85%. This is how the car sits today. If the new owner wishes, it would be very simple to reduce the size of the supercharger pulley, replace the injectors with 80pounders and with some tweaking of fuel pump voltage or maybe twin in-tank pumps easily make 700 at the wheels with a new tune. (Note that the tune is a '2 Bar' tune - very easy to tweak at the dyno). Stock 1992 ECM.

There are many, many other features of this car:
1. Alcohol Injection / Charger cooling.. 2 stage boost referenced
2. Boost and fuel pressure gauges
3. Permanent wide band set up
4. Custom Exhaust
5. Roll Bar
6. ZF Doc shifter
7. Spec stage 3+ clutch
8. Huge Brembo front brakes
9. QA1 Coilovers
10. All aluminum radiator

The car has fully functioning A/C (although probably needs a charge this summer, I last charged it in 2009). It will sit all day in Atlanta traffic without any overheating, gets close to 20mpg on the freeway. It is also very street friendly - the combination of low compression and centrifugal boost means that it is very easy to drive in traffic at lower RPM's. Above 3500 RPM's and full throttle .. watch out. :)

The car is ready to jump in and drive - no issue with flying into Atlanta and taking a road trip home.

There's so much more to this car, I'll add more to this thread as questions come in. I'll post pictures next.

Note that I travel extensively on business, there may be an occasional delay to questions on this thread.
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Here's a good introduction to the car - this video was taken in Aug 2012 after I put the new exhaust system on the car. Since this video was taken there have been a few upgrades to the fuel system including an aeromotive adjustable fuel pressure regulator (it runs at stock fuel pressure), and the large aero pump.


..and here's the initial Dyno run.. there have been about 12-15 dyno runs since this video was taken.



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Are the seats fully functional?

Functional, yes but I think the gearbox on the passenger seat is going out. It moves fine without a heavy occupant in the seat.

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