Just wondering what knock will sound like in this car. Will it be experienced by the car just pulling timing or will you hear it like you would when punching and old mid seventies car where the timing was off and hear that ticking sound?

I am experinecing the car running real rich on a very conservative tune under part throttle on hot days. It will buck a little, show 10's on the afr and be real sluggish when hot.

I have an appointment for a tune in about a month, but I would like to try puting a half degree to a degree back in the 4 pounds of boost range as the tune is very conservative and see what happens.

I am trying to figure out if the car is knocking because it is too hot, or (since this is a piggy back EMU) that the ecu is pulling extra because of the high intake temp and there is too much pulled. I have read that pulling too much timing the car will not run right, be sluggish and run hot. I'd like to start by increasing timing a half a degree and see what happens, and maybe another half, but do not know what a little knock will be like. Will it be audible ticking, or will the car just bog because it senses it and pulls the timing back out? And I do not want to harm the engine.

I am leaning towards I have too much timing pulled because I was told the tune was very conservative to start with. I think it is pulling between 4-6 degrees at 4 pounds of boost all the way through the rpm range. That is why I suspect that if the stock ECU reads a high intake temp and pulls a couple more points it could be too much retard.

I do not think the EMU will datalog knock.

 

Are you turbo or SC?

You can hear the marbles in a tin can when severe, but don’t bank on that to tune your car. Plus it depends on how loud your exhaust is, if you can discern detonation noise over the noise of the car, sometimes you can and sometimes you cant. It is easier to hear at lower rpm.

The afr will lean out some as you advance timing, so that is one indication you are making progress, if the car starts to detonate, its possible you may see no change in afr.

It is true that too much timing retard can cause higher then wanted combustion temps, you can even start melting exhaust valves and pistons in really severe situations.

But this is all just with the assumption that your timing curve is too conservative, we really don’t know. High IAT isnt an indication of EGT, you may just have poor cooling, or poor environment and as a result you’re going to run richer naturally, due to less air being consumed. You can compensate your afr tables by pulling fuel at set IAT points if you want. Be careful though, hot and lean afr can surely cause detonation.

 

I am SOT MP62 supercharged and have the PWR barrel intercooler. The intercooler works well, but the intake air pickup is just above the header in this application, gonna look at a couple things to help that out for a winter project. After long drives in the heat the intercooler is cool to the touch, and I changed the coolant recently, the guage never goes above three bars, but I have not recently datalogged water temps. Stock exhaust so not that loud, have never heard anything to me that ever sounded like knock, but there is also some supercharger whine to deal with, which is not really that loud under the conditions I want to toy with, (partial boost).

It used to do what I described above under full throttle, but I pulled a half a point across the board under the full boost part of the map because it was pulling 10 degrees under full boost across the board on about 8-8.5 pounds of boost. That seemed like a lot of timing pull and I had read that a rule of thumb for base tune should be about 1 degree per lb of boost, (some say .75 degrees) until you can get it on the dyno. So I pulled a half a point and it ran better and also leaner, and by that it went out of the 10's and into the mid 11's low 12's where the map was supposed to put it running off the wideband.

I'd like to try the same in the midrange and put back another half degree and see what happens, but there is less "padding" in the map at partial boost as there is at full boost.

Just want to know what to watch out for so as not to do damage and be able to spot trouble.

As far as hot and lean, it may get hot, but I think above 6000 rpm it is always in the low twelve to mid eleven range for AFR and from all my reading, that seems to be where most people think it should be. So under boost and above 6000rpm, I get from about 12.2 to 11.6, obviously getting richer as the rpms go up.

 

Yeah, I don’t have much experience with the curve of a roots charger to lend much more input. To be safe I'd probably suggest leaving the timing alone there and just remove some fuel instead, to get you out of the 10’s. That is really too rich as you know and can cause fuel wash at lower rpms.

If you got leaner when you retarded timing up top, I’m wondering if you weren’t experiencing some detonation there previously, sounds like you made a positive difference. Running as much timing and fuel before detonation is where your going to yield the most power, so reducing timing and seeing the car lean out tells me you may have gone past your efficient threshold and may have been detonation present. You could try playing with a degree or two in the mid and see what response you get as a test and can always put it back to where it was if you’re comfortable with that. If it were me I’d probably try it.

 

Chances are, you'll only hear it if its severe. You should be relying on your knock sensor, not your ears, for the most part.

 

I think I might try to play with it a little. I just saw your post in the other thread about how one of the SC kit makers did not find it necessary to pull any timing under 5-6 pounds of boost. I don't know if that is with or without an intercooler, but at any rate, I am pulling 4 to 6 degrees with only four pounds of boost and an intercooler. The only difference between the two should be the heat they give of between a roots and a centufgal but I would think it would not be so different that I need to pull as much as six degrees more with less boost.

 

This is very true, however I think there may be one other factor besides heat, I have to think there is more "load" being placed on a roots charged engine vs centrifugal one. You’re talking only 2 psi by 6k rpm vs yours? (5-6psi at redline remember for a base comptech kit, its a centrifugal) So also keep that in mind before you go getting crazy.
Your more apt to detonation under 6k rpm then a base Comptech kit.

Also another thing to consider is what rpm is your vtec now kicking in? Timing is drastically effected depending on when cam profile your running on. You are apt to detonate less on vtec, the engine wants timing when you lower vtec engagement so you have more boost you can safely play with in that area if you leave the timign alone. If your vtec is in stock 5800rpm location, then increasing timing under that rpm has less leeway under boost. Make sense?

For example, on my high boost comptech I can run 5-6psi under 5800rpm without detonation because my vtec is lowered to 3500rpm, from 3500 rpm to the stock 5800rpm vtec, it needs timing, or leave the timing alone and use boost. In this respect you may be ok, depending on where your vtec is set and how much boost it’s making in that area. More boost at lower rpm is harder on the engine however, just from a load standpoint, but that doesn’t mean it is detonating, just means it would be more prone to under stresses. I use an Aftercooler btw.

 

Just double checked the map, there is much less timing pulled in the low boost range than I thought, I will just leave it until I get it to the tuner.

As far as the boost curve goes, you are at 4-5 pounds instantly when you hit the throttle and then jumping up to 8psi (my pulley) very quickly after that. You can hit full boost just about anywhere in the rev range dpending on how much throttle you apply. Vtec is set to 4000, but the timing is most likely to be very conservative there as there is no change in the timing retard between 2-4k and 4-6k, the timing retard is roughly the same. I will still wait for the dyno though, better safe then sorry.

 

I had a lot of detonatio with my Greddy Kit, you could def HEAR it! When I pulled off the turbo it was BRIGHT white, lotss heat

 

Yep, all that boost at low rpm is going to make your timing very sensitive, you need to be more careful in that rpm range. The ramp up you get is much more severe then any centrifugal.