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Huzaaaaaaah! Had a pretty good day a few months ago when Mr Techlenburg squeezed the puddin' out of the ole fuel-to-noise converter's prehistoric turbo:
10 psi (spring) on 93/E9 - 360
14 psi on 93/E9 - 430
21 psi on E78 - 558 ("Triple Nickles")
Here's the last dozen or so runs:
Not too shabby for a 70-ish degree day on DD rollers. Even got an unexpected "Nice hot rod you have there" from the guy that tuned the Motec on one of the few remaining P-51 Mustangs... Guess I'll call it a "****-hot" day. Time for medals and pints!
Last edited by Carlos Iglesias; Jan 8, 2025 at 06:31 PM.
@estevan62274, really appreciate it brotha! Certainly, you fully understand what it's like for a long project to culminate in an unexpected over-achievement. I was expecting <500rwhp, so the rollers (on that dyno in particular) offered a nice windfall for all the (knuckle) blood, sweat, and (expense) tears. Oh yeah, and the wipers (just barely) work AND the fuel pump air-raid siren has been ball-gagged by PWM control. So there!! No more yellow clown car with the obnoxious engine prime to kick around at DGRR. More WINNING!
Learning **** with each phase of development is part of the process, and the most surprising discovery was the genius of Paul Yaw... well maybe not SOOO surprising. I was cautiously surprised by the coils he chose when he tuned the car's original Motec M4, and yet they performed without a glitch. So what would be the betting line...
FC coils?
Mercury Marine coils?
Lance Nist coils?
IGN1a coils?
GTR coils?
R8 oils?
.
.
.
yep, you guessed it: Nissan Sentra coils. Smart cookie indeed!!
Last edited by Carlos Iglesias; Jan 10, 2025 at 05:46 AM.
I've heard Honda drag racers making over 1000hp on the factory Honda K20 or K24 ignition coils, but they are usually using a 16V battery which helps. I think 555 on a rotary is more impressive, since our engines have half the time available between spark events. Do you have a picture showing how the Sentra coils are mounted on your car, Carlos?
@scotty305 You can see them just under the driver-side strut brace. I've been contemplating converting them to coil-on-plug, but it's a low-priority thought.
Nissan Sentra coils under driver-side strut brace
I've gotta admit that the only caveat I expressed to Shane when we started the tune was that I expect the coils to be the limiting factor. Well, the score turned out to be Yaw 1 / Iglesias 0. Which then begs the question... since they're only 35mJ/7.5A coils, at what load/charge do our engines REALLY need 100mJ coils that are so popular?! This has been fairly eye-opening for me.
Depends mostly on how much boost, how rich and what plugs/gap one runs. I had a FD on the dyno last week and w the stock plugs BUR8EQ it would breakup on the leading at 1 bar. no misfire but still way down in power as it were the trailing plugs setting off the flame front 13 deg late. I was running close to .7 lambda on E5 pump fuel. Just swapping to R7425-10 plugs fixed the breakup.
At work we had a DI piston engine doing approx 225 hp/l on pump fuel and at high rpm WOT we had also the issue that some cylinders would get the slow or lazy combustion events and if pushed further complete misfiring cycles. the root cause for this was the geometry of the intake manifold causing a less then optimal charge motion. what fixed the issue without going the route of individual spark timing per cylinder (so 4-5 deg more advanced on the worst burning cylinders) was to put proper ignition on it. We tried first various inductive coils and plugs gaps and plug orientation with not alot of succes. up to the 150 mJ IGN1-A. then we put a M&W CDI and to our surprise all cylinders burned pretty much stable and delivered a equal IMEP. afterwards we went back to inductive and made a proper intake manifold w long straight runners and this also fixed the issue. because the apllication had no room for a proper intake mani the way ahead is spark timing per cylinder up to 5-6 deg delta and still the covariance of the imep on soe cylinders is over 3-4% at rated power.
therefore what I learned is more ignition energy is always better. at high rpm you really need to be able to set the flame front off properly in the shortest possible time. w the inductive one can get like 150 mJ easily but this is delivered over like a 1 msec spark duration whereas w a CDI you have the same energy in 0.1 ms or less. 1 ms at 8000 rpm is over 40 deg crank angle.
Which then begs the question... since they're only 35mJ/7.5A coils, at what load/charge do our engines REALLY need 100mJ coils that are so popular?! This has been fairly eye-opening for me.
charge time is a factor too. it the RPM these engines are capable of running, you need a coil that charges quickly.
If you run wasted spark on the leading for sure yes. At 8000 rpm 1 rev is 7.5 msec. 1 msec spark durarion gives 6.5 msec to charge. With wasted spark though you need to fire every 180 deg so that is only like 2.5 msec left to charge and that already narrows the choice of coil quite a but if you want 100+ mJ w less then 2.5 msec dwell at 14v
Very nice. Part of me likes the idea of running the IGN1A coils that others have reported good results with, and another part of me likes the idea of finding some coil-on-plug coils from a modern car to avoid needing spark plug wires. Nice to know that Nissan Sentra (?) coils worked for you, with spark plug wires added. The IGN1A coils have three ground wires, and I've heard of some people having bad experiences if the each of them was not wired to the proper place per the manufacturer instructions.
Very nice. Part of me likes the idea of running the IGN1A coils that others have reported good results with, and another part of me likes the idea of finding some coil-on-plug coils from a modern car to avoid needing spark plug wires.
I've been following/watching some of the TAS coverage from this past weekend, and I noticed something that looks suspiciously like a coil on plug kit on a REW block in the background of the HKS booth. I haven't seen anyone discuss this in detail yet, but I hope someone got to talk with them or got some information about the system.
There are people already manufacturing R35 coil on plug conversions for the 13B. So it may be a setup similar to that. The R35 coil has an amazing output and really is only behind that of an IGN1A. The issue with the IGN1A is wiring, sufficient power, and grounding. The R35 coil is 3 wires and simple to power and wire up. PRP did a whole huge test on these coils that is worth a watch on YouTube.
From talking to actual engine builders (maily 2JZ community) and drag racers, the IGN1A is very useful in alternative fuel racing like methanol. For most other builds, they recommend the R35 coil for pump and E85.
There are people already manufacturing R35 coil on plug conversions for the 13B. So it may be a setup similar to that. The R35 coil has an amazing output and really is only behind that of an IGN1A. The issue with the IGN1A is wiring, sufficient power, and grounding. The R35 coil is 3 wires and simple to power and wire up. PRP did a whole huge test on these coils that is worth a watch on YouTube.
contemplate how important it is to check your plugs. contemplate the additional work required to check your plugs.
pass
IDK, I understand what you're saying, but if if the COP brackets are smartly designed so it's easy enough to remove and access the coils & plugs for servicing, then you're eliminating a couple of potential failure points relative to delivering properly timed ignition - plug wires will eventually wear out/fail, and if said plug wires are of lower quality to begin with, and/or not routed well enough to avoid EMI/cross-fire, a COP setup can save an expensive engine from going kaboom.
