I guess partly because I'm an old school Chevy tuning guy.



Not exactly. It does run the same heat range as the sedans. The Montero was spec'd with a heat range 5 and the sedans were spec'd with a heat range 6 which is a colder plug than the Montero.

BPR5ES-11 = Montero

BPR6ES-11 = Diamante SOHC

BKR6ES-11 = Diamante DOHC
BKR6ES-11 = 3000GT non-turbo
BKR6ES-11 = 3000GT VR-4 turbo

In NGK terminology, the following are the codes

1st Character
B = 14mm hex size

2nd Character
P = projected insulator type
K = 5/8" projected tip

3rd Character
R = resistor type

4th Character
2 = hot -> <- 12 = cold

5th Character
E = 3/4" thread reach

6th Character
S = standard center electrode type

7th (and 8th if used) Character
11 = .044" gap

I agree that the heat range 6 plug with the standard gap should work fine. I did get detonation in the prior engine with heat range 5 plugs, but that wasn't the only issue. In this case, I was trying to get some extra insurance until the tune was finished..... but too much insurance isn't always a good thing.

Frank

The only real difference is the reduced wrench size.

How so when the OE Montero plug is a heat range 5 and the others are a heat range 6?

Perhaps it isn't a large difference, but there's enough difference between the heat range 5 and heat range 7 that my engine won't start.

I'm ordering a BPR6ES-11 set and will see how they work - I agree that they should be fine since the Diamante SOHC heads are the same. As for the combustion chamber, I tend to look at the piston top as a part of the chamber during combustion and mine is different since I have a full dished top instead of the normal squish area of the 8.9:1 pistons. I suspect the lack of squish area might also be a reason why the heat range 7 plugs won't fire the mixture.

Frank

Sorry I was refering to the all the higher powered engines. I have done no work with the Montero SOHC engine.

I just got a set of BPR6ES-11 NGKs from AutoZone. When I get back from the exhaust shop tomorrow I'll install them and see how they work.

Frank

Frank, these are the mitsu spec for the 2v Starion. I know, different chambers, but the heat ranges are all the same at 7. With your lower boost, 6 sounds right to start with.

BUR7ES-11 Alternate plug BPR7ES-11 or BP7ES11

The heat range 6 plugs work - maybe a little longer cranking time, but they seem ok at idle.

Charlie, I have the dwell set at 3.1. I backed it off until I heard definite idle misfires around 2.0, but in between the 2 values, the idle wasn't as smooth, so I set it back to 3.1. Would I be better off to cut it back to just above definite misfire and then readjust the VE table tune... or leave it where it is? What have you found Mitsubishi coils to need as a minimum dwell?

Frank

My stuff has all been up in the 3.6 range.

Thanks - maybe I'll try raising the dwell and see if it starts easier. From your experience, I guess the OE coil can take that much dwell without damage.

Frank

Try working on the voltage compensation rather than raising the base dwell. You may need to be up in the 5 to 6 range when cranking.