Miata Mailing List: September 1996, Message #0075
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   From: Hans Mattes 

Subject: Re: *charger survey

   Date: Sat, 31 Aug 1996 19:54:33 -0500



Greg Bassett wrote:

> 

> At 07:32 PM 8/30/96 -0400, Steve Barr wrote:

> >This discussion of *chargers is clearly of interest to the

> >list (and to me :-) as I hope to get one next year).

> >

> >Would those of you who have one please answer the following

> >questions?  I'm probably not the best person to make up

> >the questions, but here goes:

> >

> >1. What year car and size engine do you have?

> 

>   1990 Silver 1600, 5 speed, limited slip

> 

> >2. What *charger do you have?

> 

>   Bell Aerodyne with intercooler and MSD spark control (Stage II?)

> 

> >3. How many miles did the car have on it before *charging?\

> 

>   135,000

> 

> >4. Any mechanical problems before *charging?

> 

>   Previous owner replaced one brake caliper at about 85,000 mi. 

    Other than that and two replacements of timing belt, NOTHING

     has been done (Original clutch, never had the head off)

       Typical Miata

> 

> >5. What other relevant modifications (vents, headers, etc.)

> >have you made to your Miata and (if possible) when did you

> >make them?

> 

>   Konis, heavy sway bars, agressive alignment, several stiffening

     bars front and rear, RedLine xmission & rear end lubes, tires &

     wheels (15x7 w. P-Zero 205/50 x 15 for street -- 13x7 w. BFG R1

     215/50 x 13 for autocross), Walker muffler, homemade fuel/air

     meter (voltmeter off the O2 sensor) -- I made most of the 

     suspension changes before putting on the turbo -- 

     they changed the car's balance so that it felt underpowered.  

	The turbo "rebalanced" the car -- at a MUCH higher level.



> >6. What boost do you run and what is your estimated

> >horsepower?

> 

>    8 psi, with 13 degrees static spark advance.

      I've been told that the engine develops around 195 hp.

      I have made the following measurements of my car's performance:



	27 mph -> 55 mph -- 2nd gear      3.2 seconds

	50 mph -> 70 mph -- 3rd gear	  3.3 seconds

	50 mph -> 70 mph -- 5th gear	  6.3 seconds



     These are the average of several runs, with outlier measurements

     discarded as indicating measurement error.



     At various track events, the car has been about as fast as turbo

     Mitsubishi 3000's and recent Porsches on the straights.  Being a

     Miata, and several hundreds of pounds lighter, it has generally

     been faster in the corners.  Brakes are weak in this application.

    

> >

> >7. How many miles do you now have on your Miata?

> 

     155,000

> 

> >8. Any mechanical problems since *charging?

> 

     Killed my cat -- probably a combination of rich mixture at full

       boost and 140,000 miles.  No trouble since replacement.



     And the turbo, itself, clogged up with its own lube and acted

       erratically (the mfg. repair it for a "nominal" cost.)

> 

> >9. What sort of driving do you do (for example: X% commute,

> >X% autox, etc.) in the car?

>  

      Daily driver.  15,000 annual milage 

      Autocross.     15 events annually, 150 autocross laps (50 miles?)

      Track events.   1 event annually, 5 half-hour sessions (150

miles?)

> >

> >10. Please share any hard performance numbers and/or

> >the subjective 'feel' of how your Miata drives with the

> >*charger.

> 

>     Hard numbers (as available) given above.

       Subjectively, fast and fun.  It's hard to imagine anything else

       that delivers anywhere near as much fun per dollar -- and maybe

       that delivers as much fun at any dollar.  Certainly not any

       coupe (Supra, BMW, etc.) and probably not any "thick" sportscar

       (911, Z3, SLK).  Maybe a Boxter.  Maybe a fast Westfield or

Lotus.

       But it's nice not to have to walk home. 

> >

> >11. Anything else which you feel is important to know about

> >your car for this survey?

> 

>    From everything I can find, the outstanding durability I'm seeing

      in my car is typical of the 1600 Miata.  When I bought the car,

two

      years ago with 135,000 miles, I expected to rebuild the engine.  I

      measured the compression dry and wet (see below) and decided to

let

      it break before I fixed it.  I then measured it again, in 9/95,

      after a year of turbo operation:



        CYLINDER		 1	 2	 3	 4



	5/94 dry		160	157	154	153

	5/94 wet		174	166	162	165

	9/95 wet		168	159	154	167



     If it is deteriorating, it is doing so slowly.















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