Vance,
I just couldn't sit by and let your comments about TBI for the TR6 go
without response. I am that guy, Rick Patton, doing the TBI conversions.
Your comments about TBI are correct to a degree but you fail to mention
other benefits.
>But throttle body injection will not get you much if any additional power
by itself.
You say there is no benefit performance wise. Ok in a car that is perfectly
tuned, (how many list members have perfectly tuned cars?) there is not much
horsepower gain from TBI. Agreed but there IS a noticeable difference. The
majority of TR6's need tuning and how many mess with synchronizing, needles,
timing curves, etc? TBI takes care of that and more.
>You get drivability and emissions with TBI because of it's extreme
precision,
> and it's ability to make minute adjustments via feedback from an O2
sensor.
Exactly! Don't most people want drivability? It's so nice to hop in the car
and go without reservation. It runs great cold, hot, and in between! No
messing around.
>Multi-port gets you more power because you eliminate mixture variation
across the cylinders
>so each cylinder is optimized, but TBI suffers from the same distribution
issues as a
> carburetor.
I have been driving a TR6 converted to multi-port for going on three years
now. Control is done by Electromotive TEC3 ECM (that just came back from
repair at the manufacture's shop today). Yes MPI can balance cylinders but
only in full sequential mode and it is not a huge issue on the 6. Until
recently most factory MPI cars fired injectors in batch mode and therefore
couldn't effectively balance cylinders. Reading the plugs in Aaron's 1970
TBI TR6 shows that they are running very very close to each other.
>you seldom (never?) see TBI on cars any more -
>the emissions regs are so strict that you cannot afford to permit any
variation across the cylinders.
Yes strict emissions along with faster, more sophisticated, lower cost,
engine management systems have moved away from TBI just like we moved from
carbs to TBI.
There are other benefits:
Fully electronic ignition. No points, vacuum, or mechanical advance.
Automatically adjusts for temperature and load.
The GM ECM has the ability to learn. It remembers what it needs to do to
make the engine run properly according to the way YOU drive. Try that with
carbs!
GM TBI also has the ability to datalog. Yes you can take a 15 or 20 minute
trip then review all the engine events like rpm and sensor data on a laptop
at home.
It is a GM product adapted to a TR6. So if you can convince your
neighborhood mechanic that it is a Chevy, even though it doesn't look like
any Chevy he has ever seen, he can diagnose it and repair it. It has a check
engine light and gives a code to assist troubleshooting.
Parts are available at most auto parts stores nationwide and at reasonable
prices!
It's affordable at about half the cost of an MPI system, and a quarter to a
third the cost of a supercharger MPI system.
And Vance, if you are a technically inclined you can reprogram the ECM your
way. All that's required is an $85 flash programmer, low cost software
(tunercat.com), and a laptop. You can change fuel maps, timing advance maps,
etc.
OK Ok rant off. Guess it just upset me to have you dismiss TBI because it
doesn't yield as much horsepower as MPI. The same can be said about
superchargers versus turbos and on and on, cost not withstanding. My
multi-port car is about to be upgraded with a supercharger and that means
that the tuning process will need to start all over and it has never really
stopped since installation three years ago!
rant off once again,
have a great 4th,
Rick Patton
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