Need some very specific info: Here is the situation: RX8 with GReddy turbo kit running unspecified map with GReddy boost controller set to 6 lbs of boost. (note: this boost controller makes a rapid clicking sound.) I listen to the car intently and make note of all the new sounds that it makes. I know what the discription for knock sounds like (marbles in a can) but I need a very detailed discription of what knock sounds like. For instance, how long does this sound last when it happens? How loud? What does marbles in a can sound like for that matter? I ask because maybe once or twice I have heard a very brief sound at full boost that I am pretty sure was not the boost controller (though it could have been). Yes, I have my head in my *** with no wb cause innovate is backordered now for a week!

Second, what is the sound that the turbo makes when you let off the gas but when you dont have enought boost to cause the bov to open? I have heard that people call this surge. This could be, because, if you know what surge is, (it is essentially when the turbo is operating at the left hand axis of the efficency plot) then you know that the turbo is not moving air when you close the throttle plate. So it could stall. But this is not the same kind of surge when you are at lugging the engine at WOT, which is very bad for the turbo. Is surge caused by throttle lift as bad? (that is if this sound is surge.)

 

Well, I'm pretty familiar with both the sound of the boost controller and the sound of pinging. But, I have to say that I never had pinging below 9psi or 6kRPM. That's when I started pulling timing on the leading plugs. Problem solved. They can be hard to differentiate. But, you could turn off the solenoid and if you still hear the sound, its probably pinging. In general the pinging is erratic while the solenoid is more regular. Listening for the location of the sound is also key. I have the solenoid mounted on the RHS. So when I heard the pinging, it was noticably more towards center than the solenoid clicking.

Of course, running without your WBO2 is asking for trouble!!

Regarding the sound of surge, if you aren't boosting enough to cause the BOV to open, don't worry about it. You aren't going to cause any turbo damage by reflecting a pressure wave of ~0psi off the throttle plate back to the turbo. Besides, you are probably just hearing the BOV fluttering. The SSQV, which is what I have, is known for that sound.

 

the best way to describe the way knock sounds like is cracking your nuckles. imagine like 30 people doing that one after another without missing a beat and that's pretty close. that's a lot closer than the marbles or popcorn.

 

^ not really. You can get plenty of audible pinging with no damage. Also, knock sensors are notorious for behaving badly. They retard when you hit a bump and do nothing when a real detonation occurs.

 

Thanks MadDog. "Sound" advice. I'll put the WB in on Monday as backorder should be filled by this weekend. So when you say " never had pinging below 9psi or 6kRPM" is that an inclusive or exclusive "or"? I mean to say, if you run 6kRPM at 6psi, would you expect the possibility of detonation on your car? Also, the sound of a rotary detonating is completely different than the common piston ping??? I just want to be clear. I believe that i did experience a little ping, though only a split second and it was quite quiet, if it happened at all.

Yeah, I didnt think that that low boost "surge" could be all that harmful. I have to live with it anyway. My bov is set perfectly such that a 1/32 of a turn softer and the car stalls on high-boost throttle tip-out.



Guitar, Thank you. I think that is a good discription of what I heard, though it was so short that it is hard to say with 100% assurance. Much more common sound than marbles. Also, you posted something about 600cc Siemans injectors a short while ago. Why? Do you think that they would fit? If so how did you go about determining that?


Sung, seen your posts around. Facinating.

 

If you really want to be able to listen for detonation, make yourself a set of det-cans. I made a set a few weeks ago and have been using them to listen for detonation since the temp has been going up here. They work great. You can hear everything going on inside the engine.

By the way. There are several shops around here that stock the LC-1. If the order doesn't work out, you might consider cancelling that order and picking one up from them

 

WHAT? Why didn't you tell me that before? Been waiting forever. And whats a det can (I can imagine, but specifics would be good.)?

 

I can tell you that my motor did not 'ping' for very long.I got off the power the moment I heard but it was already too late.I was at ~8000rpm at about 5 psi.The only special circumstance was stale fuel of unknown octane rating.The Renessis did not 'ping' much more than the TII I damaged several years ago.
My rebuilt motor is in and running happily on Sunoco 94 with an added can of Octane booster!

 

To make a set of det cans you need the following:
Actual values may vary, but these worked well for me.

-25ft of hard but flexible plastic or rubber tubing. Try a few different types of tubing, some transmit sound better than others. Generally the harder the rubber, the better it will carry sound. The best tube I found was 3/8" ID air compressor hosing from wal-mart.
-1 set of ear protectors
-1 8" or so peice of 3/8" diameter copper tubing.
-1 T connector (preferably metal)
-Couple hose clamps


Beat the end of the copper tube completely flat. Drill a hold in the flat end. If you blow in the open end of the tube, it should be air tight. Insert open end of copper pipe into 25ft rubber tube, clamp it.

Drill holes in the sides of the ear protectors. Cut off 4 feet from the 25ft peice of tubing. Cut this into 2 2ft sections. Insert 1 peice into each end of ear protectors. Connect these two peices to the main 21ft peice using the T connector. Clamp connections down.

Run the 21ft tube through the firewall and bolt it to the engine. I used the bolts at the front, right side of the block.

Play with it to achieve best sound transmition. You'd be amazed how well you can hear the engine.

 

like mad dog said, don't worry about the fluttering. turbo damage only occurs when high boost bounces back to the turbo (and yea, the SSQV will make that sound alot cruising around town at part throttle)

 

hate to over simplify it after you put so much work into it, but why not use a $6 mechanic's stethescope and some extra vacuum line if you're gonna do it that way? $10 and 3 minutes and you're good to go.

 

1. The mechanics stethescope is not easily bolted to the engine
2. The large ear protectors remove all background noise so you can really hear the engine.
3. I don't think the tubing in the mechanics stethescope would transmit sound as well over a 25ft distance.

I wanted to be able to hear as much as possible inside the engine, a steth. would probably work, but I thought this would work better.

Myne didn't cost that much, maybe $30 and only took 20 min to make.

 

why 25 feet?

 

Well it actually ended up being about 20ft. But it bolted to the front of the engine ran through the engine bay through the firewall on the passenger side and up and over to the driver side. I wanted enough slack that I am free to move around without running out of line. Plus the Tee'd portion uses twice as much since there are 2 lines.

 

i feel like i'm cheating... my knock sensor has a headphone output