What is the heat range on a FR3LS compared to a R44TS or R44XLS?

 

I believe its a tad colder, but I'm pretty much lot now because I see FR5LS, MR43LTS, and 41-904 to be the same heat range from the chart on the scoggin dicey web site. I'd like to know an answer too...

 

firgured it out.... got this from AC Delco's web site
R = Resistor
4 = 14 mm Thread
5 = Heat Range
T = Taper Seat
S = Extended Tip

Prefix
Suffix
Numbering


Plug Identification Table
Prefix
B - Series Gap
C - Commercial
CS - Chain Saw
F - Fine Line 14 mm 5/8" Hex
M - Marine
LM - Lawn mower type
R - Resistor
S - Shielded (5/8-24 thread)
V - Surface Gap
Prefixes are sometimes combined e.g., VB, CR

Suffix
A - Clip Gap
C - Copper Core Center Electrode
C - Colder Version of M44 Plug
E - Special Design Electrode Extended Tip
F - 1/2" (12.7 mm) reach
FF - 1/2" (12.7 mm) reach, fully threaded
G - Pin Gap (cold -running)
I - Iridium Center Electrode
J - Boot Release Agent, Anti-Seize Compound
K - Special Design
L - Long Reach
7/16" (11.1mm) reach, (14mm) thread
3/4" (19mm) reach, (18mm) thread
3/4" (19mm) reach, (14mm) thread (fineline)
LT - Long reach, .715" (18.16 mm), Tapered Seat
M - Special Design Electrode
N - 3/4" (19 mm) reach, 3/8" (9.5 mm) thread length
R - Resistor (Sport Vehicle Plugs)
S - Extended Tip
S - 7/8" (22.3mm) Moderate Long reach 23/32" (18.25mm)
T - Tapered Seat Shell Design
TS - Tapered seat with extended tip
X - Wide Gap (H.E.I.) (high energy ignition)
XL - Extra Long reach, 3/4" (19 mm) fully threaded
Y - 3 prong cloverleaf electrode
Z - Special gap (usually denotes wide gap)
5 - .050" (1.3 mm) gap
6 - .060" (1.5 mm) gap
8 - .080" (2 mm) gap
100 - Iridium
600 - Resistor Type
800 - Platinum Type
900 - Double Platinum Type
Suffixes are combined to form such AC suffix designations as FG, XLS, TS, FFM, TSX, SZ, etc.



Numbering

1st number denotes THREAD SIZE

2nd number denotes
HEAT RANGE

In the early 1990s an all numeric identification code was developed to ensure that the proper spark plug would be selected for replacement in specific engine applications. The numeric code does not in any way correspond to the heat range of the spark plug. Therefore, selection of a spark plug with a different code number is not recommended. The heat ranges may be drastically different between two different plugs and engine damage or poor performance may result.

The prefix "41" stands for the manufacturer's product line (i.e., 41= spark plug)

Numbers after the prefix indicate the type of spark plug and also the specific application:

100–199 = Iridium

600–699 = Resistor

800–999 = Double Platinum

 

The way it appears to me is the FR3LS is one heat range colder then the R44TS. Is this right?

 

thats what i thought but check this out.

http://www.sallee-chevrolet.com/Chev...ckV8s/355.html

Look where is mentioned the "Accessories" The 5.7-liter High Output engine assembly also includes a torsional damper, a cast iron water pump (standard rotation, long-style), a 12 3/4" diameter automatic transmission flexplate (153 tooth ring gear), and a dipstick. It does not include spark plug wires, pulleys, exhaust manifolds, a starter motor, an oil filter adapter, a fuel pump, or external accessories. Note: Service with eight AC FR5LS, 904, or MR43LTS spark plugs. If colder heat range is required, use FR3LS.

Wouldnt one think that the MR43LTS plugs were the same as the FR3LS?

 

The MR is a marine application plug so they might be built hotter, I'm not sure to tell ya the truth. I guess I'll get it running with the FR3LS and before I spray it I'll check with the guys on the power adder board

 

i think the marine (M) plugs are not hotter than normal ones. But they have a stanless steel base. In germany they sell only the m version
( maybe cause of the salty cold winter?)