Engine: spark plug selection experts?

[t walgamuth]

Hi I had my engine rebuilt on my race car and my machinist discarded my plugs. Unfortunately I don't know what they were so don't know what to buy. Is there a website which I can go to and figure out what plugs I need based on the specs of my engine?

The engine is modified to run on E85 with double the flow as compared to its stock gasoline diet. It also has a 9200 rpm rev limit. It is a K20a2 Acura engine.

Wondering how different the plugs might need to be compared to stock.

[Mike Van Veghten]

You have a "race car" and you don't know what spark plugs you are running..?
I was under the impression pretty good details of the car/chassis/engine/trans./gear ratios/tires/etc. were kept...

How did you come to use...whatever plug your machine shop threw away ? Just retrace your original spark plug search.

Mike

[DEEPNHOCK]

Stick a set of these in and run them an hour and 'read' them.

NGK (7746) IFR7G-11KS Laser Iridium Spark Plug

Here's a chart to help you figure out which way to go after you've read the plugs.

[t walgamuth]

Stick a set of these in and run them an hour and 'read' them.

NGK (7746) IFR7G-11KS Laser Iridium Spark Plug

Here's a chart to help you figure out which way to go after you've read the plugs.

Thanks Jeff!
Will the chart work for a car running E85?

[DEEPNHOCK]

E-85 is still fuel.
You are going to be running about 20% more of it through your system.
Here's a pretty good explanation of E-85 and A/FR ratio's..

http://www.hotrod.com/how-to/engine/1307-wideband-oxygen-sensor/

[t walgamuth]

I did some more searching and the consensus seems to be to use stock plugs. So I'll start there.

[karterfred88]

I did some more searching and the consensus seems to be to use stock plugs. So I'll start there.

Going to the racing Acura/Honda sites, some show E85 use, the prevailing opinion seems to be stock, plus one range hotter. Hope you changed injectors, too!

[t walgamuth]

In autocross you spend a lot of time idling and waiting in line to run, then redline and back down to 2000 rpm about 20 times per run. So hopefully the stock plug will be fine.

[t walgamuth]

You have a "race car" and you don't know what spark plugs you are running..?
I was under the impression pretty good details of the car/chassis/engine/trans./gear ratios/tires/etc. were kept...

How did you come to use...whatever plug your machine shop threw away ? Just retrace your original spark plug search.

Mike

Hi Mike. I'm not sure why you quotate "race car"...? The car is a dedicated autocross car, not legal to drive on the street. It weighs about 1200
# and has 220 hp at the rear wheels.

I bought it last spring and ran the season without ever touching the plugs. it was running fine so why mess with it? It was fast enough to win its 6th national championship driven by Jeff Cashmore the PO who did provide me with lots of notes and specifications....but could not tell me what plugs were used, neither could Del Long the builder of the car and many other national championship autocross cars.

So, yes I am embarressed to admit I did not know what the plugs were but then I am in good company with that.