Spark plug heat range for turbo LSX?

[280Z28]

I really want to order my plugs before my motor is built because there's a lead time on them (custom parts.. kinda) and my motor is already pushing the deadlines I was trying to meet.

 

I'm using NGK plugs. The company that's modifying them (Optrand) wants a part number so they can run my quotes, which means I have to figure out which NGKs I'm looking at. I want to use their iridium tip, platinum base racing plugs. From everything I can tell so far, my guess is a 9-10 heat range. :dunno:

 

It's an 8.7:1, 407ci LSX block/L92 heads (until I lift them) with 2bars boost that should see 7400rpm. What would you recommend for plugs (in particular heat range, since that's what I can't change later easily)?

[dr_hunt]

9-10 should be about right. 7400 rpm, why?? Especially on boost, 2 bar, that's like 29psi! Unless that's a built motor with rods, pistons, etc. that'd be a grenade at 7400.

[280Z28]

9-10 should be about right. 7400 rpm, why?? Especially on boost, 2 bar, that's like 29psi! Unless that's a built motor with rods, pistons, etc. that'd be a grenade at 7400.

 

Lunati crank, Carrillo rods

 

Only a 3.75" stroke.

 

Got some recommendations to use a TR6 (heat range 6), which is common in turbo'd LSx motors, but I'm not sure the guys that suggested it realized that this isn't your average turbo LSx.

[dr_hunt]

I can't imagine 2 bar with that setup. You should be in the 1200HP range at around 20psi on gas, assuming the turbo configuration is correct. What's your entire engine package look like?

[280Z28]

I can't imagine 2 bar with that setup. You should be in the 1200HP range at around 20psi on gas, assuming the turbo configuration is correct. What's your entire engine package look like?

 

LSX block, lunati crank, carrillo rods, (builder's picking) 8.7:1 pistons. 407ci = 4.155"x3.75", Comp R lifters, L92 heads (want to see what they'll handle before they lift, at which point we look at GM's 6 bolt heads. AirWerks S88 turbo, 48mm ProGate, big I/C :dunno:

 

If we don't hit 2 bar, it'll at least be close.

 

I'm doing the electronics on this one, the build is being left to a professional. I would just break something probably, even though they're "unbreakable" lol..

[dr_hunt]

Sean at Solid technology, has a 408 ls motor with an 88mm turbo. I think it is in the 1200HP range at about 22psi. Beyond that the heads lift with the stock stud size. Go to the 1/2" studs for alittle more "room".

[280Z28]

Sean at Solid technology, has a 408 ls motor with an 88mm turbo. I think it is in the 1200HP range at about 22psi. Beyond that the heads lift with the stock stud size. Go to the 1/2" studs for alittle more "room".

 

I may be even farther from 2bar (I said 2bar when I was originally thinking 25-26 which is actually like 1.7bar). My builder decided on a 4" stroke instead of the 3.75", so it'll be a 434. He's using a Callies Magnum XL crank and the pistons are custom dished JE.

 

My "weak" heads will probably be a limiting factor for a while, but when I do change them, I don't want to have to build another bottom end. Definitely a case of I only want to build it once so I'll build it so it won't break even if we move to 6-stud heads.

 

Back on the topic of plugs, I'm leaning towards the NGK TR8IX Iridium plugs.