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ngk heat range on 150 shot

Posted: Sun Jan 12, 2020 5:33 pm
by evil16v
Hello all, it's been a while.

I'm new to nitrous and relatively new to the motor in my car (specs in sig). I bought the motor/trans/convertor from another buick guy who went 11.0x @122 with it, in a very similar car to mine, NA. Motor made 590ish flywheel. Engine builder told me to run 34° locked, and do.

I have a nx single entry crossbar on the way. It has tune ups for 50-300. I will only be spraying 150 of it with an NOS Mini progressive, due to rod limitations. I have some tuning to do as it appears rich and has not been tuned at this altitude. So that will come first before spray. the plugs are filthy right now from idle/street driving. So i dont have a good point of reference. They are NGK R5671A-8. Ill probably tune it up with another set of 8s on NA before i swap to colder. Then work on the nitrous.

The question is, does this seem cold already? Nitrous express recommends 2 ranges colder, which would be a R5671A-10. The previous owner and builder said they were going to try nitous late in the season, ran into problems and didn't. Think they left cold plugs in it from that? Edelbrock recommends a 5 range, but these heads have a good deal of work, and this motor makes a bit more steam than they were intended to. Getting ready order a few sets from rock auto, and wondering what to buy. 9s... 10s..?

Also, how do think this will work with my combo? Cam is:
Intake. Exaust
Valve lift. .566. .543
Adv. Dur. 277° 290°
Dur@ .050" 251° 260°
Open Close
INT 17.5 BTDC 53.5 ABDC
EXH 66.0 BBDC 14.0 ATDC
Lobe Separation: 112°
Degreed to 108°

Any help would be appreciated.

Re: ngk heat range on 150 shot

Posted: Mon Jan 13, 2020 11:03 am
by Bruce69Camaro
According to most nos kit manufacturers, they recommend to step down at least 1 heat range for a 100 - 150 shot and 2 heat ranges over 150 shot.
I was running NGK R5673-7 on my 150 shot.

Re: ngk heat range on 150 shot

Posted: Mon Jan 13, 2020 1:15 pm
by evil16v
Bruce69Camaro wrote: Mon Jan 13, 2020 11:03 am According to most nos kit manufacturers, they recommend to step down at least 1 heat range for a 100 - 150 shot and 2 heat ranges over 150 shot.
I was running NGK R5673-7 on my 150 shot.
That's what NX recommended. Problem is, i suspect what i have is too cold to start with. I don't have a good point of reference to go two colder from. If i simply go two colder i am at a 10 for a 150 shot. So i am trying to find a point of reference from someone doing something similar.

You say you run a 7. What compression and fuel are you running? I'm 11:1 and plan on 100 or better fuel.

Re: ngk heat range on 150 shot

Posted: Mon Jan 13, 2020 1:21 pm
by Bruce69Camaro
My compression was around 11.5:1 and I was running 110 octane.

Re: ngk heat range on 150 shot

Posted: Mon Jan 13, 2020 2:42 pm
by evil16v
:thumb:

Ok, that makes it relative for sure. Thanks!