Have had the chance to beat on my car a decent bit now and log it. Got it running well at ~6psi, but I'm pretty sure I'm hearing pretty significant detonation above 4000rpm. I've been letting out of it at that point of course. I went from 12:1 and 30* to 11.5:1 and 30* and it maybe got a little bit better, but not much. NA I ran 36* WOT with no issues. I hate to pull more timing than I need, should I try dosing it with more fuel or is that timing still too high? Running 93 octane, likely E10, probably not oxygenated now this late in the year.

Back pressure testing resulted in a very twitchy needle on the gauge, but ballpark it's certainly possible I'm near 3:1 ratio up at that rpm, which could also be hurting me. Air temp got as high as 160*

 

IMO I would pull more timing. What compression ratio? Why not start low, and add a couple degrees at a time?

 

G'day mate,

I know you don't wanna do it, but pull timing and see what happens.
As for your twitchy back pressure gauge, try fitting a restrictor in the line to the gauge, ie a .020 thou hole should do it, most trucks run a restrictor in the gauge line to stop a flickering gauge needle.
3.1 back pressure ratio is not gonna help your detonation problems either

 

If you have audible detonation on a turbo car you have a huge problem. 11.5:1 is more than safe unless you have a cylinder not getting the same mixture. Pull four degrees of timing. If it's still audible you have another issue. What spark plugs are you running? The backpressure is increasing the likelihood of detonation though.

 

a guy might make sure all the plugs look the same (as far as rich lean) and i have to jump on board with pulling some more timing

 

Cooling the intake temps would help too.

 

8.8:1, should have said that. Plugs are now quite hard to get to, but it had always burned very even NA EFI. Plugs are bosch platinums. I do have water injection I want to add this winter.

 

Get rid of those bosch platinums there likely glowing and switch to an 8 or 9 heat range ngk plug i bet this will help lots!!!

 

I do like the ngks.Mine would detinate on my 318 at 160to 170 iat.W/W fluid would drop them to 70 and 80 iats when it was 100+ ambient temps.Didnt affect afrs that much

 

What are the part numbers on those Bosch Platinums?

 

pretty sure these are the ones, they were on closeout on rockauto

http://www.rockauto.com/catalog/moreinfo.php?pk=272206

why would they be an issue. I was under the impression that at 5-6psi I probably would be ok with stock heat range? As a street car I don't want to go too cold on the plug.

 

Do you have an upgraded ignition? If so, going one heat range colder to help keep heat out of the plug will probably not affect much as far as fouling or anything like that. Hope that helps!

 

MSD6 + blaster2 coil. Anyone got a good link to a plug chart that shows part numbers for heat ranges for various brands?

 

You have ballzrunning and platinum plug in a turbo setup. It is simply a huge no no, and just think about all the edges on a plat 4 that could glow red and cause problems.

 

I have no turbo-specific experience with bosch platinums but just lots of n/a experience. I have NEVER seen one single car run well on bosch platinum plugs. ever. not once.

Just my $.02

Sam

 

These are not the ones with the 4 electrodes, they are a conventional looking plug. Taking that away, what is inherently wrong about a platinum plug in a turbo engine? I bought them cuz they were dirt cheap on closeout and assumed they would be an upgrade.

 

XR5 is what ngk part number is for a 383-440 and XRIX5 or iridiums. The higher the number the lower the heat range so a 6 would be one heat range lower, 7 equals 2 ranges lower. I'm not sure what makes the platinum plugs bad but I put a set in my reg neon and it ran like crap, for some reason they just don't work good for some cars, I ran them for the same reason cheap.

 

Higher numbers is lower heat range, and vice versa on NGK plugs. I just went from an LZTR5AIX-13 to an LZTR6AIX-13 in my challenger to drop 1 heat range. Most plugs I think go this way from what I recall. Iridium is harder and has better heat handling characteristics than platinum, so a good choice for forced induction, but copper is cheap and works great! Just need to change them out more frequently Good luck!

 

I liked how the hemis use the same plug as my srt4 did lol

 

Yeah Actually I think it was LZTR5AP-13, cuz Platinum's came out and Iridiums went in... Something like that anyway