From: chris@speckle (Chris Schanzle)
Newsgroups: rec.autos
Subject: Re: Turbocharging a '91 Honda CRX Si....
Date: 14 Sep 92 22:10:57 GMT

In <24941@oasys.dt.navy.mil> goldberg@oasys.dt.navy.mil (Mark Goldberg) writes:
>In rec.autos, ssr@siberia.cypress.com (Bapcha/FPGA) writes:
>>How could I turbocharge my '91 CRX Si.... I really love that car - but
>>heck - I could use some turbo boost....
>>How much will it cost me to get it installed ?  Do I lose my factory
>>warranty if I do that before 36K miles ?  And how much hp would I
>>gain for how much of a loss in fuel economy....
>>Just toying with the idea....

>I hope you go no further than toying with the idea.  Turbocharged engines
>are configured from the ground up for turbocharging.  The process increases
>system heat and can have serious consequences on the wear of bearings,
>seals, and rings.   The camshafts, intake manifolds, injectors exhaust
>system, and general under-hood layout must be specifically designed.
>The mechanical load bearing parts must also be strong enough to handle
>the extra power.

I used to think the same ideas before I put a turbo on my '87 CRX si
at 33,000 miles.  But with about 30,000 miles of REALLY hard driving
at 12 (and more recently, 14) pounds of boost (182 to 200 HP) and
autocrossing two years, my CRX has suffered only two failures.  They
were replaced over a year ago with upgraded parts available at your
local Honda parts counter: heavy duty clutch and transmission input
shaft bearing.  Not bad.

Since I didn't get a very nicely balanced engine from the factory,
(more severe vibration at 5,500 rpms and up) I replaced the connecting
rod bearings last fall for precautionary reasons only.  My compression
ratio is reduced via thicker metal head gasket from 8.7 to 8.0.  I
wish I never put it in, since it hurts my bottom-end torque, but I
can squish 15 pounds of boost into that cylinder without detonation.

I currently run with a set of 295 cc/min Toyota injectors in my car
(stock is 185 cc/min).  My friend runs the Honda Accord 235 cc/min
injectors that I ran on until I wanted more than 12 PSI.  Stock cam,
valves, rockers, pistons, crank, flywheel, thermostat, intake
manifold, throttle body.  Did I miss something?   Oh yes, computer.

About a year ago I bought a new fuel/ignition computer: the
Electromotive TEC computer with a pair of direct-fire coils that I can
program with a PC-laptop.  It's MUCH more flexible than the Haltech
unit, with the additional functionality of closed loop operation (with
O2 sensor) and ignition timing control (the latter is VERY important
on a turbo car).  It's very challenging (and fun) to get just right.

My best friend also has the HKS turbo on his car with about 60,000
miles on the turbo (over 100K on the engine).  For the first 25K or so
he was running at 5.5 PSI and later upgraded to an intercooler, bigger
injectors, and 8.5 PSI of boost (stock compression ratio).  He
replaced his clutch with the same heavy-duty Honda set when he moved
up in boost.  Note: Centerforce clutches for the Honda suck; can't
hold more than 10 PSI w/o slipping on a good day.  Other than that, he
has had no failures.  He got a nicely balanced engine; he runs up to
7,000 RPM regularly.  No kidding.  His engine has no cooling problems;
mine is marginal with the A/C condenser in front of the entire
radiator, but has never gotten "hot" -- my cooling fan kicks in more
often and runs longer.  He gets in the mid to upper 30's (better than
mine) commuting in and out of Baltimore City.  Near 40 mpg on the
highway.  He stuck with the stock Honda ECU and HKS's piggy-back
computer to give more fuel in boost.  Thus, he retains that great,
efficient sequential injection.

Sure, two cars isn't much of a base to draw a conclusion with, but I
do think it says a lot for how Honda basically designed the '87 genre
CRX's.  For example, I haven't had my CV joint crumble when taking off
the line with 225 mm wide ultra-sticky Hoosier Autocrosser tires.

If you don't like working on cars and theorizing about them and trying
to get the most out of an engine, I would NOT recommend adding a turbo
to a normally aspiriated engine.  Nor can I comment on how well the
'88 and up model years hold up to the extra power.

Yes, run a synthetic through those turbo bearings.  Yes, change the
oil at 3000 miles.  Yes, if you turn up the boost, you must make sure
the timing and fuel delivery is correct.  You might need to adjust the
valve clearances to the widest spec to give them more time to cool on
the head.  Do it GRADUALLY!!!  Find a way to monitor fuel mixture.
Don't be stupid!!

An engine is a complex system of parts that work together.  With time,
I've learned an amazing amount about these things.  With a LOT of
time...
_______________

Chris Schanzle, Computer Scientist, NIST	chris@speckle.ncsl.nist.gov

"...you can state that claim - good work is the key to good fortune
Winners take that praise, losers seldom take that blame..."  -- Rush, RTB