VHPD spark plugs

I just got my S1 back with verniers fitted and a fully mapped Emerald ECU. It is a different car, no smells, pulls from 2k, idles etc. It made 188 bhp on his dyno which is probably as good as an otherwise standard VHPD can manage.

Tuner thinks the Champion spark plugs I have fitted are rubbish and recommends NGK IRIDIUM. I think, before it was remapped, it went better on the Champion ones than the Ngk R that were installed.

It looks like the correct iridium ones are BPR7EIX. Does anyone have any informed recommendations?

Always go with what the guy mapping suggests. They may not be the best, personal preference, its Friday, etc but guarantee they will have mapped/seen more than anyone on here will have done.

That number does seem to ring a bell, but the easiest way is to take one out that’s currently fitted.

Sounds boring to me! :open_mouth: :smiley:

BPR7EIX is the correct NGK plug. Denso equivalent is IK22, which I’ve used and found to be very good.

Hi Winthatt,

I’m curious who the tuner was that recommended this spark plug? I’ve had my car looked at recently and the garage reckoned the iridium spark plugs were incorrect. Interesting… I really would like to learn who this tuner was so I can have a chat with them. I want my car to run the best it can and these engines do seem a little fickle.


Hi Winthatt,

The standard plugs are BKR7E (iridium version is BKR7EIX) which show as having a 16mm hex but the BPRs you’ve been recommnded are a 21mm hex, otherwise both have the same 14mm thread and 19mm reach. Would a 21mm spark plug socket even fit down the hole?

Whichever you end up using, and even though all the gaps are supposedly preset now, check them before fitting.

I did fit some Iridium plugs to my car and they fit and work. Can’t remember the exact part number. It was mapped with Champion (new) plugs fitted and he recommended changing them to a better quality plug. I think he said the Champion plugs were poor rather than recommend a make. When I switched over to them the car was even better pulling from low revs. It has little torque down low (by design) but is less inclined to stumble. With the std Lotus ECU and 190 update I rated my car as bloomin dangerous as it would bog down at junctions etc. When we nearly had an event with my young son in the car it was the last straw. Emerald, Verniers and remapping followed.

My car was mapped by “Kevin” at Autotech in Ripley Derbyshire. I spent 15 years of my life running a company that designed engine controllers so I am a minor expert. It was obvious to me that Kevin knows his stuff and has a good dyno. He also makes his own ECU though I had an Emerald already. We discussed the pros and cons of a 68332 and 167 micro at length and how he does the crank timing. He is a qualified EE. In short, I rate him and his judgement.

Hope that helps.I had used Champion for years in Minis, MGs and my Elise. I think the Iridiums make the car run better.

Interesting to hear about your Exige, they do appear to be quite fickle little machines don’t they. I must admit mine has always felt really responsive and sharp low down. A big contrast to the another car that I test drove. Mine had iridium plugs in it and I was told these were the wrong heat range for the engine so they have been replaced. I’m not convinced however and from hearing your experience it seems they can work quite well.

I’ll see if I can get my old plugs back and try them again instead I think!

I’m using NGK Iridium BKR7EIX without any issues.

Another vote for NKG BKR7EIX Iridium plugs - fitted today along with a new NGK lambda sensor from Elise Parts and the car is back to rude health :sunglasses:
In fact it is bonkers quick, it’s just ridiculous, it’s ballistic ! :crazy:

Mine is in literally the same state of modification and just been through the same exercise. My car hit 180 bhp, and likewise really driveable following tune. It was 166bhp when it went in. Feedback I got is 166-170 is pretty normal in real world (non marketing) figuring for an Exige.

I don’t have much to bench mark against etc but if feels healthy enough…

Some feedback from another Exige S1 owner - I had running issues with the previous plugs and also lambda sensor, now with the NGK BKR7EIX Iridium plugs the change is significant, I really mean that. I would be interested to see rolling road figures for both the plugs, now it drives with such urgent throttle response and eagerness. So pleased :slight_smile:

I can’t help feel mine is not quite singing. I have Verniers, emerald and large bore 421. It made 180 on a rolling road right after I got it so I shouldn’t grumble. But I feel the timing map at full throttle needs work. The car has the basic emerald map with a tuning session by the people who fitted it. i fitted a wide and to see if having more control would help. I’m now going to get a set of plugs as the experience is similar and I think it’s got champions in it.

What I would like to do is get it mapped. It still struggles to idle when hot and over fuels enough to chuck flames out on track. Any recommendations? I’ve noted the chap in Derbyshire. :slight_smile:

Try the NGK Iridium plugs, ‘singing’ is exactly howI would describe the little Lotus now, it is ballistic all the way through the rev range. It feels forced induction fast. Also the emissions are now pretty much spot on even with no cat, close to 300ppm HC. Give it a whirl, order from Opie Oils and they will happily match best price found elsewhere.

Interestingly looking into this a bit and the Copper NGK plugs should be better, but they are less resistant to fouling so maybe the Iridium versions work better with mega rich maps.

I have the NGK BCPR7ES and the car ran ok. I’ve ordered a set of the Iridium versions to see if they make a difference.

Confirmed there was no significant difference between the copper and Iridium versions.