Hello,
I am interested in adding twin turbo chargers to my 1994 LT1 (donated from a
Caprice police cruiser) that will be swapped into my 1989 Jaguar XJ-S
sportscar. I have a pair of smaller sized turbos that would give more
benefit at lower RPM versus larger units that would work better at higher
RPM even though the smaller turbos might limit the top end power. The Jaguar
has a 2.88:1 rear gear ratio and with an overdrive automatic transmission
will cruise at 65 mph running about 1700 rpm. My goal is to improve the low
rpm torque operation (BMEP) because the car will seldom be run over 3500
rpm. I would like to optimize it for the best possible gas mileage for
around town and highway performance. It will have to meet emissions testing
requirements for Phoenix, AZ.
Aside from the issue of emissions, I want to know what would be needed to be
done to the engine and electronics to allow the twin turbos to work properly
on the LT1? I have read that the only real issue is with having a device
that senses the positive pressure boost created by the turbos which will
cause the fuel pressure regulator to increase the fuel pressure to the
injectors by a corresponding amount so that the fuel ratio stays on track
with the programming of the Powertrain Command Module. Would that be
correct? Is there anything else required?
The two turbos that I have are of small size to work with the engine in the
1000-3000 RPM range most effectively. My goal is not to create horsepower
(high RMP applications) but to create more torque (low RPM applications). In
fact, the turbos may actually run out of boost at high RPM. I am wanting to
increase the Brake Mean Effective Pressure (BMEP) of the engine which has a
direct effect on the torque curve and engine efficiency. This is a stock
factory 1994 Chevy LT1 5.7 liter V-8.
What would need to be done to the engine and electronics to allow the twin
turbos to work best? Would any reprogramming of the PCM be required or only
optional to suit ones preferences?
Would there be a need to change the compression ratio or type of gasoline
used or does the PCM effectively control the detonation or knock via sensors
and timing changes?
Would it be better to place the turbos at the inlet of the mass air flow
sensor or would it be better to place the turbos between the mass air flow
sensor and the throttlebodies at the front of the intake manifold?
Is there a recommended selection of an automatic 4 speed transmission for
the Jaguar swap and what are the pros and cons of the 700R-4 versus the
4L60E transmissions?
Is there an exhaust manifold that could be recommend for the twin turbo
setup?
I’m also wanting to dress-up the engine to make it look special in my
Jaguar’s engine bay. Are there any suggestions?
Thank you for your reply and have a great day,
Brent Wiscombe
bwiscombe@msn.com
Mesa, AZ