'89 Daytona C/S NHRA Stocker

[ShelGame]

OK, so I couldn't wait to try out the WB PEFTBL adjuster deal that's in MP Tune.

One thing I learned this weekend for sure, is that the transient fuelling can be very different from the intended AFR target. I was (am) going very lean on launch as the boost rises. Basically, the boost is rising faster than the original pump-shot calibration could keep up with. So, I'm still tuning that. But, the point there is, you don't want to use that data to tune the PEFTBL. It will give you bad results. So, I looked for data where the boost was constant. Unfortunately, since the launch is nearly all transient fuelling, that 'good' data is all 4500rpm-5500rpm. But, I think it will still be useful for testing the PEFTBL adjustment in MP Tune. Here's what I got with my data on the 2nd run :



I made a cal based on this data: 1st, I decided that 11.5 is too lean for this car (Mitsu turbo, hot 20psi boost, no IC). So, I adjusted the calculation to 11.2. And, I moved the PEFTBL down to ~3 points above the MP Tune suggestion.

I'll try it next time I get the car out, probably in 2 weeks.

[ShelGame]

Looking at my data a little more closely today. And, I think that the BPSx controller does have a weakness - it seems to have a pretty slow response.

The lean AFR I'm seeing on launch, I don't think is due to the MAP rising and lack of PumpShot; it's just lag in the AFR reading. When I stage, I'm going very lean (~15:1 !!). It's not yet in boost, but under some load (on the torque converter). It's not knocking either, but I enriched that area just in case.

I'll post a screenshot later, but you can see that there is a bit of lag on going lean while staging, and then when going WOT on launch. Kind of makes me want to get the LC-1 working. Supposedly, Innovate has the most responsive WBO2 controllers out there.



EDIT: reading more on the internetz it seems that the response time I'm seeing is not out of the ordinary for the RPM range. It has more to do with the engine than the sensor itself. Some data posted for the LC-1 seems like it's pretty similar to this one. Of course, it's hard to tell in an apples to oranges comparison...

[Vigo]

Well, im definitely following your opinion/experience with the BPSx stuff so if you decide it is perfectly good make sure to say so at some point! I know it might be early to recommend it without putting some further use on it.

[ShelGame]

Well, it takes ~3 seconds after I got WOT for the AFR to fall from 15:1 to the 10:1 it was reading at WOT and full boost. Maybe some of that was transient fuel delay. Even then, there is a 2 second delay from when I get to full boost to when the AFR reads 10:1. So, there's at least a 2 second delay for ~3 point AFR swing.

I wish it was faster responding than that. While the sensor is lagging, you can't tell what's really going on with the AFR. And, that's maybe the most important area to tune for drag racing. Getting off the line affects the entire run.

By contrast, I just looked at an old data log, and the NBO2 sensor went from full rich (~0.9v) to full lean (0.0v) in about 0.25seconds.

[cordes]

Well, it takes ~3 seconds after I got WOT for the AFR to fall from 15:1 to the 10:1 it was reading at WOT and full boost. Maybe some of that was transient fuel delay. Even then, there is a 2 second delay from when I get to full boost to when the AFR reads 10:1. So, there's at least a 2 second delay for ~3 point AFR swing.

I wish it was faster responding than that. While the sensor is lagging, you can't tell what's really going on with the AFR. And, that's maybe the most important area to tune for drag racing. Getting off the line affects the entire run.

By contrast, I just looked at an old data log, and the NBO2 sensor went from full rich (~0.9v) to full lean (0.0v) in about 0.25seconds.

Even time vs. voltage change the NBO2 wins. that really says something IMO.

[ShelGame]

Looking over my old and new data the past couple of days and one thing is clear - I always get knock on Cyl#4 at around 5100rpm. In previous cals, I cured it by just being way rich (like 10:1 AFR, apparently).

Tuning it last Saturday, one thing I noticed is each time I would take out fuel, I would pick up more knock - but only on #4, and usually above 5k rpm. To the point now I have less timing above 5k than stock. Since it's only (or at least mostly) on Cyl #4, I've been reading about the #4 coolant mod and I think I'm going to do this conversion. Soon. I already bought all the parts necessary to convert my cooling system to -16 AN fittings and hoses. So, I think a #4 cooling mod will be part of that conversion. After reviewing everything on here about it, I'm going with the WP-->#4 supply (AKA Euro Style or Lugert Style). That should give nice cool water to #4 and let me run more timing at high RPM...

[GLHS60]

Looking forward to your results. The #4 coolant mod has proven effective many times and it will be great to follow your back to back tests!!

Thanks
Randy

[cordes]

I'll be interested to see your results. I've always wondered how effective it really is when taking it from the pump to the head directly. I don't see a huge pressure differential there in my mind, but at the same time there should be some pretty good losses as it moves through the head.

[GLHS60]

Just to clarify the #4 coolant mod is to allow the stagnant coolant out of the end of the head not to push cool water into it.

Thanks
Randy

[cordes]

Just to clarify the #4 coolant mod is to allow the stagnant coolant out of the end of the head not to push cool water into it.

Thanks
Randy

I've seen some guys run pressurized water from the top of the pump to it rather than drain it to the bottom hose side.

[Vigo]

Yeah, if you take it from the 'top' of the water pump housing, i'd think it would be trying to push coolant into the head at #4. Does this car have a heater core? If not, you could run the #4 coolant into the water pump barb for the heater return.

[GLHS60]

I prefer running a hose from the end of the cylinder head to a Y in the upper rad hose. Allows the stagnant coolant to flow in the normal direction to be cooled by the rad. Heater hose method is O.K. too. Some folks like to run from the cylinder head to the water pump inlet to circulate the hot head water directly back into the hot block. The water pump really only circulates coolant, doesn't really pump it so I can't see it pumping any coolant into the end of the head against normal cooling system pressure. The good thing about this discussion is Rob is right on the edge and will be able to determine if knock is eliminated by whatever method he chooses.

Thanks
Randy

[ShelGame]

Yeah, if you take it from the 'top' of the water pump housing, i'd think it would be trying to push coolant into the head at #4. Does this car have a heater core? If not, you could run the #4 coolant into the water pump barb for the heater return.

No, no heater. But I wanted to run the #4 coolant from the WP outlet. Push cool water into #4, rather than draw hot water out...

[ShelGame]

Just to clarify the #4 coolant mod is to allow the stagnant coolant out of the end of the head not to push cool water into it.

Thanks
Randy

Both methods have been tried. I want to try to push cool water into #4. Since I have no heater circuit, and an electric water pump, I think a little cooler temp in that area is a good idea...

[Vigo]

Ok, can't wait to see how it works.

The good thing about this discussion is Rob is right on the edge and will be able to determine if knock is eliminated by whatever method he chooses.

Agreed!

[RoadWarrior222]

The bad thing about this discussion is that Rob is right on the edge and will blow his motor if he picks wrong and it makes it worse


... that shouldn't really happen though... but while you're playing around, there's no "law" that says you have to run the same heat range plug in each cylinder... thinking that that colder ones will also maybe just lower compression fractionally. (Or if you wanted you could chop 2 threads off in a horseshoe round to the ground strap and give yourself a quarter cc or something there.)

[Rrider]

Colder plugs have more material and raise compression slightly, at least when you're talking staying with the same type. That is an interesting idea about running mismatched plugs.. never would have thought of doing that.

[T1 woodywagon]

Rob you better double check the rule book, I am not sure if we can do that mod in our class.

[ShelGame]

Rob you better double check the rule book, I am not sure if we can do that mod in our class.

There's nothing in the rules specifically about the cooling system. Water pump, and radiator, are specified. Of course, the rules are written as 'allowed modifications'; so if it's not listed it's technically not allowed. But, I doubt anyone would notice a small extra water line. Unless I were to be protested specifically for the line, I can't see it being a problem.

One thing that does concern me is the plan I have for the rest of the cooling system - going to AN lines. That will be obvious, and I had planned to solder in brass fittings to the radiator. The radiator is specified to be 'stock' for the model. So, I maybe not be able to go forward with the rad hose swap. It would have been only a small weight savings anyway.

[RoadWarrior222]

Colder plugs have more material and raise compression slightly, at least when you're talking staying with the same type. That is an interesting idea about running mismatched plugs.. never would have thought of doing that.

Yeah I thought further back there was more material to couple the electrode to the body better thermally, but was thinking they pulled the nose in some relative to hotter plugs. But I guess if there's less space down inside the plugs that will affect compression also.

But anyway, if you're looking for every ounce of performance and one cylinder is keeping you slow, may as well try stuff to keep that one happy so you don't have to turn down the other three. If for example say you were pinging on 15* advance and not on 14* you might try keeping it at 15 and widening the gap on the plug in that cylinder, the extra delay from the voltage having to build a bit higher before it would spark would be effectively a slight retard just for that cylinder. Or you check your injector flow rates and get 51lb, 51lb, 50.9lb and 51.8lb... (Which is probably a pretty close spread for randomly chosen ones) guess where you should put the slightly richer one. Or to avoid pulling them all go through your spares to find the one that flows heaviest and swap that one in.