Unrestricted to black plate

J

jayo48

Member
What kind of power drop would one expect going from unrestricted to the one hole black plate? Not looking for dyno numbers much, just a kind of general idea.
 
Very little -- without going back several years to the last black plate animal we built for a champ kart, I am thinking it was 1/2 to 3/4 CHP less.
Same jetting and timing - put the plate in and run it.

-----
?Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
30 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 
Just wanted to dig this back up and see if the answer is still the same? We will probably be running unrestricted and some black plate races next year and trying to decide if we need multiple motors. Thans
 
What size is the black plate? Seems to me, with less air, you need less fuel. How much less I don't know. Maybe one jet size would be too much. You might need a 1/4 size less, or maybe a 1/2 size less. That's with all things being equal i.e. same air density.
 
drt27 said:
Just wanted to dig this back up and see if the answer is still the same? We will probably be running unrestricted and some black plate races next year and trying to decide if we need multiple motors. Thans
Click to expand...
Nothing has changed. This is still the way we build them today -- you will NOT need another engine. Slip the plate and rest. plate in and run it.
 
alvin l nunley said:
If nothing has changed, why have A black plate at all?
Click to expand...
The tune on the carb hasn't changed. The power the engine makes (and subsequent speed the car runs) has changed.
Often times a black plate is used to slow the cars down on high speed tracks (1/4 mi' pavement oval champs is most popular.) Another reason is parity of matching other engine combinations (clone, LO206, flathead, etc.)

FWIW, we used to run .0005" (half thou.) richer main in the black plate engines but didn't see enough difference in performance to merit the confusion for most customers. In my experience, most customers would rather change the clip on the needle for rich/lean adjustments rather than pull the bowl and change the main jet. Understandable. You can do pretty much the same thing with the needle clip adjustments.
 
CarlsonMotorsports said:
The tune on the carb hasn't changed. The power the engine makes (and subsequent speed the car runs) has changed.
Click to expand...

I'm surprised that drivers can't feel the difference that 2.6% change in fuel flow makes.
 

Attachments

  • 38_35_5 jet change.jpg
    38_35_5 jet change.jpg
    158 KB · Views: 24
You must log in or register to reply here.
Back
Top