13B-RX3

iTrader: (2)

My apologies you obviously have done your homework. I had come up with vastly different results but i wasn't using an Oscilloscope.

Jobro

iTrader: (2)

Yeah thats fair enough. I'm not saying VR is better for everyone everywhere. I mean properly used it probably should be better. I agree with you about the wiring being a pain in the ***. I had never ending problems with the VR sensor until I went spastic with my wiring rout directly avoiding everything (alternator, coils,plugs,leads, injectors, bacv wire, etc).

Its just mods like this sometimes don't pay off, you spend all this time and money and effort changing from a stock CAS to a complicated and obscure hall effect setup no one else uses and then what do you do when it doesn't work. I personally own a 60-2 trigger wheel that I could potentially mount in front of my front crank on the front pulley. But I had a hard time finding a sensor that could operate with such a small wheel with so many teeth. It has 60 teeth inside a 3.5" wheel. Bigger would look ugly.

Fair enough if Brian is sure that the ignition pickup system as a whole caused a timing problem. Its just the problem is unlikely specifically with the CAS so much as the interaction of the whole system. Millions of production vehicles use VR sensors without a hitch.

BDC

Indeed, the last statement is true. That's part of the head shaking. If you've got any other ideas as to why this has happened twice, I'm all ears.

B

pmrobert

I think you referred to an unshielded VR cable? As you run at a higher engine load combustion chamber pressures get progressively higher and this increases the breakdown voltage of the spark gap. This increases the EMI (ElectroMagnetic Interference) generation by several different mechanisms. You have a transmitter (your ignition system in several ways) and a receiving antenna (your VR cable with a shielding deficiency). The ECU can only detect and compensate for unusual signals on the VR input in so many ways. The more crap you sling at, the more likely to find that one set of circumstances where it generates a grossly maltimed spark at the worst possible time, under boost and high load. The higher spark voltage also increases the chance of crossfire which has nothing to do with VR noise. That's a couple of scenarios I can think of...

DarkKnightFC

If this is the case, then this is a fantastic lesson about the devil being in the details. Ignition and fuel obviously being the most important things in the equation are the ones that often don't get the attention that they deserve. Brian how many miles do you have on the wires? With the amount of voltage required to fire that mixture you're throwing in there, I have no doubt that if there is any breakdown in the insulation then it probably looks like a thunderstorm under your hood. Obviously good shielding is a must seeing as how it HAS to be there but it didn't seem to pose a problem before so you may have just put it in the back of your mind. Have you tried locating the magnets closer to the teeth to get a stronger signal? I lot of guys slide a piece of paper in there, tighten it up, spin it and the paper comes out, now you have your air gap. Absolutely nothing should be ran near the alternator as it will cause interference if possible. With the amount of power you're putting out and the results you're trying to achieve, everything else has to work like charm, and there should be no corners cut. And I'm certainly not saying that you cut corners by any means, but when you are focused on a certain project, the little things tend to be put on a shelf or just taken for granted. I can't wait to see her up and running again. Share some of your secret block prep tecniques with us when you're building it.

Chris

ronbros3

those darn rotarys, i have my pile of broken ones in back of house!
just when things are gettin good, PUFF the magic Dragon!

Ques: is it possible for the Apex to lift off the housing,because of rpm harmonics, when its lifted could combustion blow back into the compressed intake charge that is coming up for tdc, that would make it fire ,like 80-90* btdc, at that point things could get messy.

THX RON

Jobro

iTrader: (2)

Thats pretty much what I got from the posts too.

Brian have you post pictures of your VR cable? Is it screen 4 core microphone cable?
Also have you got a picture of where you route it? Maybe there is a more friendy place to run it that is probably more functional but ugly.

ronbros3

after reading thru this topic it seems as tho everybody is taking a guess as to what happened to Brains engine, and the thread has just about bogged down.

Stop and be somewhat logical, he was pushing close to 25psi , timing was pretty hi up, in both max and split, and we all know that alcohol can finally reach a point of detonation, heat soak, and a list of etc..

i have built some darn good 13bs, last one, mild street port, NRS seals and springs, GT40R, good IC, good ignition, and on and on! And just when I got tuning within reasonable limits, (after learning around 8--9 blow ups later) i was very careful not to push things over the edge. 500miles on it
BOOM no warning what so ever, powdered the seals and blew them into the turbo and out the exhaust.
and yes i have a love-hate relationship with them.
i have one now, all done and sorted out starts runs perfect, but im am a little edgy with it, any thing over 17lbs, i get worried, but so far so good!!

THX RON HEY! Brian good luck with your next one!

ronbros3

i posted this question before; could a ceramic seal lift off the housing surface and then slap down against the chrome surface hard enough and shatter?? with strong springs?
and could it,the seal, be affected by a random RPM harmonic

this probably should be in another thread.

DAMIFINO THX RON

ronbros3

Brian;; reading the thread again(about 4th time), 3 things come to mind
it was a much warmer day,
you had a little more weight in the car,
you may haved filled the tank for demonstration purposes,
maybe added a little more tune to the equation?
anyway just something to ponder! THX RON

BDC

Maybe you're right Ron but I have two suspicions: One, ignition noise travelling down an otherwise unshielded trigger harness (long story) and freaking out the ECU and Two, crossfire between plug wires due to lack of wire separators and instead the use of zip ties (to keep them tied away from the many ss-braided hoses I have on the driver's side of the engine).

Hopefully I'm right and hopefully it's not a brick wall of tuning I'm running into that just flat-out won't let me run the boost and power I am with the gasoline to alcohol ratio I'm trying to throw at it. That'd be a real bummer.

My plan is to stick with the same tune job but possibly change a few things: Upgrade to a single electrode 10 heat range plug for the trailings and remove the BUR9EQs that are parked in there currently (can't hurt!), use an external reluctor and keep the crank angle sensor OR go to a hall sensor, possibly add a small M1 or M2 nozzle pre-turbo and experiment with IAT changes in boost, and who knows what else.

Pictures of disassembly coming up.

B

BDC

http://bdc.cyberosity.com/v/ProjectC...d/Disassembly/

What a mess.

AlexG13B

iTrader: (7)

i wanna see it open

KNONFS

iTrader: (14)

Glad to see some progress B!!!

Is that a S4 plate?

enzo250

I have only one.. Your tune is to aggressive for your combination..
But you'll never blame yourself instead you'll look for any other excuse.

You can test your BS theorys very simply..
Noise issues are not load dependant only rpm dependant.
So with your car at idle grab a timing light and rev the engine to the limiter and see what happens. I'm guessing you'll be fine because i use them over with over 11k rpms and have no issues.

And your second BS theory is just that BS...
I have run many engines with zip ties holding spark plugs wires together, some in million dollar boats, and there's never an issue.. Unless your wires are trashed..

BDC

I appreciate the suggestions.

B

AnthonyNYC

iTrader: (3)

Another forum member had some issues as well without an intercooler and was injecting methanol.

He was on E85 which burns cooler than gas and could not get his intake temps below 220 deg .

https://www.rx7club.com/showpost.php...8&postcount=18


For the full thread go here...

https://www.rx7club.com/rotary-drag-racing-167/just-curious-how-much-power-do-you-think-ill-make-next-week-842020/

BDC

I wonder where he stuck his nozzles. Mine are way upstream and I don't have an issue with air temps.

B

BDC

Btw, I came up with another theory on why I've cracked both irons. I noticed several days ago when I was cleaning up the exhaust ports, after having the housings blasted, that both housings' trailing plug holes had very slight lateral cracks with some darkening around those holes. The cracks aren't anywhere near as bad as others I've seen but they're there. I think that perhaps I'm running too hot a plug in the trailing for the power range - NGK BUR9EQ standard plugs. I'd just assumed that since I was running alot of alcohol that I could use the 9's but maybe I'm mistaken. This next go-around I'm putting atleast a 10.5 race plug in if not an 11.

B

AnthonyNYC

iTrader: (3)

Can you post some pictures?

Viking War Hammer

iTrader: (8)

I mounted mine as far away from the throttle body as I could.

Turblown

iTrader: (12)

I am surprised the engine didn't detonated with that high of an intake temp charge at those power levels. If you don't run an intercooler you cannot have your turbo sucking off your 200degree radiator. That in conjunction with that size of a compressor, running that much boost, and with your nozzel location; I'm not shocked you're intake temps are that high. Even if you changed to a cold air intake, with pre-comp injection you still can't run that high of boost without an inter-cooler. Unless you want to damage your compressor by running an m10 upfront ...

Viking War Hammer

iTrader: (8)

I guess the E85 kept it from detonating.

Yeah, I'm just going to stuff a intercooler on it and call it a day. I tried and failed...... I suck.

Not only was my intake temps 220 F, my water temps were the same. That little Honda radiator just didn't cut it. Again, I tried and failed. I suck.

fritts

iTrader: (5)

What type of AIT sensor are you using (closed or open element). The latency of the AIT sensor will come in to play big time with running water/?? injection. I have a hard time believing you are truely seeing a 200 deg drop in temps. I would also suggest the air/water mixture may not be completely homogenious and water may be pooling on the AIT sensor giving lower readings than what they truely are.

Viking War Hammer

iTrader: (8)

It's just a GM sensor. We wondered also, so we took the sensor out and tested it, all tested out well. The intake was stupid hot, we eventually tried putting a ice bag up there for a temp fix, but that just melted to my intake where the iat sensor is.

Wait, I never said I saw 200f degree drops in temps. I said we couldn't get the temps below 220 f.