Technical Spark plugs heat range??

[Diwiak]

Hi,

i got new spark plugs for my Sei 2001 MPi for oncoming service interval, which is Denso TwinTip K20TT (selected by seller in local parts shop), and I found now over google that seicento;s plugs should be K16TT (different heat range-20 is colder)-any idea if this is some serious difference and have to replace them??

Thanks

 

[portland_bill]

If the plug runs cooler than intended it can lead to combustion deposits on the plug tip, leading to a misfire. At least this is safer than a hotter one. May also give poor starting after they have been n a while. Take them back and get the right ones.

Never be tempted to run hotter ones, can lead to holed pistons.

There is an ideal temperature for a plug tip. The heat range of the plug is determine by the heat path from the tip to the body. Some have a longer nose before the ceramic widens to meet the metal body. Difficult to see up inside the plug. How it loses heat is determined in early engine development stages and the plug chosen then. Head design and coolant passages are key factors.

 

[Ralf S.]

Be careful of the internet. There's a lot of random information out there, some plain wrong and some just without context. (For example, plugs for the Brazil model will be different to plugs for the Norway model).

I have checked with God (aka a fella' who works at Denso Europe) and this is what he says...

It depends on your engine type/year as below (all information is for a 1.1):

(187AXB, 187AXB1A) - 187 A1.000 10/00-10/04 - K16TT
(187AXB, 187AXB1A) - 187 A1.000 11/04-01/10 - XU22TT
(187AXB, 187AXB1A) - 176 B2.000 01/98-09/00 - K20TT
(187CXB/C) - 176 B2.000 01/98-01/10 - K20TT

So, get under the hood. If the type plate says you have a 176 B2 .. then it's K20TT. If it's a 187 A1 then it comes down to when it was built.

For interest, a K16 is the same as an NGK "5" which is pretty "hot" (K20 is like an NGK "6") and could have been specified for emissions control reasons. If you have no other information to go on, then it's better to put K20TT plugs in a K16TT engine than the other way round.


Ralf S.

 

[Diwiak]

EPER says its a 187AXC1A02 version which is not listed with 187A1.000 engine /manufact. late 2001/, so now be wise

I crosschecked plugs type even from EPER data and its still pointing to K16 range.

We have wide temperatures range climate /-25 to +36C degrees/ so I personally think one heat grade colder plug wont matter.

Anyway I already changed plugs for K16TT /looks to be great offer 8,-EURs for set of 4/.

Thanks

 

[Ralf S.]

God says that a post-2000 Seicento MPI (version 187AXC1A02) must have an engine type 187 A1.000 (and I'm not going to argue with God.. ) so in your case you have the correct plugs (K16TT)

The 176.. engines look like they are SPI only... so that makes it clear cut.


Ralf S.

 

[portland_bill]

EPER says its a 187AXC1A02 version which is not listed with 187A1.000 engine /manufact. late 2001/, so now be wise

I crosschecked plugs type even from EPER data and its still pointing to K16 range.

We have wide temperatures range climate /-25 to +36C degrees/ so I personally think one heat grade colder plug wont matter.

Anyway I already changed plugs for K16TT /looks to be great offer 8,-EURs for set of 4/.

Thanks

Local climate is not relevant to plug heat range. The plug heat range is all to do with how the heat is taken from the plug tip to the cylinder head and lost to the coolant. The aim is to keep the plug tip within the best range whatever the engine. Different cylinder head designs, coolant passages, thermal efficiency, plug location in cylinder, etc., all may affect how the plug tip heat is taken away. So a different head design needs a different plug.

 

[Diwiak]

OK, gap should be 0.8 for this type, am I right??

 

[portland_bill]

No.

They should be fine as supplied.
Denso E-cat says 1.0mm for both 16 and 20 plug numbers.
http://www.denso-am.co.uk/e-catalogue/