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minor updates
found a small leak on one of couplers that goes on compression tube. nothing crazy like Howard and few others said it would have to be a massive leak. there wasn't
I did pull off the cold side pipes to check for rags (last time I work on car I pulled uim and cold side) nothing there.
I will pull plugs next and post pictures of how they are burning.
tuner seems to think it may be dyno that's off. says the hp reading is low compared to torque reading
also looks like my turbo speed was off as well. in number of blades in haltech software I put 7, should have been 14.
so i guess rpms were closer to 85-90,000 rpms
Don't get so caught up in numbers. If you look through my build thread, I was making similar numbers with high 10AFRs with a very similar build, but with the R7420-10s and the 1.05 housing with 105psi on all faces. The methanol is going to like slightly leaner numbers for power. Dynos are for calibrating and consistency and not numbers. They all read different and higher numbers sell turbos.
The current owner of my old FD at 390whp smoked a Viper on the highway too lol
Recommend more grounding on your setup Alex, and I love the Denso Iridium plugs, heat range 10 is IRE01-31 part number. I've had very good success with them on my '95 FD.... in particular they've been long lasting and don't foul as easily as the NGK in my experience.
while this is more often than not good advice, your zero smoothed dyno chart shows serous misfires. further, as been correctely mentioned, if you are at 18 psi and 85/90 K turbo speed you should be making (approx) 414, not 343. big diff.
work needs to be done to eliminate the misfires.
i also prefer the Denso alternative to the NGKs although both are wonderful and light years ahead of any other alternatives that "fit."
i cringe everytime i see people running 9s in our modded FDs.
in addition to not being a proper match as to ignition, they shorten rotor housing life by retaining too much heat around the spark plug boss, creating a much higher "spark plug mountain, spark plug mountain destroys rotor housings by lifting the apex seal off the rotor housing surface which starts an oscillating/hammering against the defensless housing. chatter marks are often the death of a housing.
most serious chatter is at the top of the housing where it is so important to build compression.
not only does chatter seriously degrade the housing but it also contributes to warping the apex seal. apex seals need housing contact to transfer heat. if they can't transfer heat they will warp and you will lose compression and power.
in both chatter and seal warpage we are just talking about degree. all housings have chatter and all seals warp over time. the question is the degree. 9 plugs in a modded engine seriously increase the degradation..
almost all chatter is due to the raised spark plug boss.
10s or colder are the answer.
Last edited by Howard Coleman; 06-10-22 at 08:31 AM.
I will use the denso 10 heat range plug now and look into my grounding. each coil has a ground to its perspective housing but I'm using a chassis ground for the other. maybe I should run it straight to battery ground in rear bin?
Denso has a thinner center electrode than NGK. thinner is thought to work better.
lighting a HIGHLY compressed charge is like trying to pound a nail into an extremely hard piece of wood.
a thinner nail is easier to drive.
here's the winner
note what they say on the box...
four tenths of one mm center electrode. (NGK is .5). i am not knocking NGK, just pointing out a difference. the alternative plugs that "fit", BR10ES, feature a 2.45 mm center electrode as do the AR3932 copper plugs.
of course you need to pick the correct heat range. here's how:
notice the ground strap. more than 50% devoid of material. running just a touch too hot. sure, you see residual carbon/oil on other parts of the plug but they are irrelevant. you want half the strap clean.
plugs should be one of the first things you check, just as tires when road racing. your tires will tell you almost everything you need to know as to setup.
Last edited by Howard Coleman; 06-11-22 at 11:39 AM.
some interesting notes for the difference between the NGK 13B 7420 and the Renesis-specific 7440 Iridium race plugs
The Renesis trailing plugs have a 2.5 mm shorter threaded 'reach" length (21.5mm L, 19.0mm T) and so there are specific L and T plugs
Hard to be sure, but electrode diameter on the 7420R and 7440R appears to be the same. The OE Renesis iridium electrode is larger; 0.8mm diameter.
The 7440R grounding strap (RH side) is visibly thicker than the 7420 (LH side) and you can also see that the Renesis plug gap is much larger (0.046" - 0.049" standard factory, allowed max is upper 0.055" T - 0.059" L)
.
In addition to the Renesis trailing plug reach being 2.5mm shorter, the 7440R ceramic end on both L and T is 1/4" shorter than the 7420 as well
I have some NGK 10’s on the way, will report back in a week if sputtering is fixed. I’ll check current plugs at that time as well, car isn’t going anywhere.
I am aware of an e85 car that uses trailings, on all spark holes, also direct fire and has no issues with spark when hitting full boost(20ish psi) up to 5500 rpm. Understandably, e85 and 93 octane are different animals.
I had a set of denso 10 range installed before. trying to see if I can find them to see how they were burning. I was running 10s until tuner suggested to run 9s instead.
Alex, what boost were you tuning to when the tuner suggested 9s?
I just changed the Denso Iridium IRE01-31 (10 HR) plugs on my FD post DGRR, with about 2000 highway miles and some hard running/Dragon runs on them. Will take and post some pics soon.
It's your car buddy, you have to do what's best for it. I wouldn't rely on any tuner's advice-- you have to make informed decisions. I'm sure you're aware of this but just so that it's plain for anyone reading.
Rich, when do you recommend going up to 10 heat range?
Depends on different factors like planned usage and budget in mind.
I've found that the various NGK race plugs are/were a bit finicky and tended to foul fairly quickly with street driving. With the Denso Iridium I've seen them last much longer, so I've gravitated towards running them much more often. This on my '95 FD with PT6466 and 15 psi low boost 20 psi high.
IMO step up from 9s to a quality 10 (no snowmobile or motorcycle plugs pls as all 10s are not created equal) when your boost/power levels are anywhere from about 400ish rwhp to low 500s. At that point you'll want to move to 10.5s. Road race environment, planned dyno power pulls or planned serious highway street racing 2F2F style, I'd be more inclined to run a colder plug as well. For a modified FD that's not driven often and spark plug budget isn't a huge concern, for my car I'm running the Denso Iridium IRE01-31.
Got it, thanks Rich! Power wise I'm at mid 300, just running seq twins on 14psi, and I have been running all 9s since I got the car in 2011. The twins are smoking a bit now after running 14psi for ~10 years. BNR is going to be in the near future when their supply issue clear up, so I was wondering if there's need to move up to 10s when that happen.
thanks for the pics. due to the multiple ground traps there isn't much of a tell.
i was one experimenting with an Autolite AR3932X which has a similar type of groundstrapping. we ran into squiggles at zero smoothing and since we were unable to tighten the gap switched to a gappable AR3932... gapped them at .023 and the misfire immediately stopped. we found an additional 50 rwhp. swap in a proper set of plugs at .023 and look at your power data at zero smoothing. if you still have squiggles you will need to take another look at all ignition components.
06-07-22, 08:35 PM
