Hi guys,
I just had my monte over to the dyno shop after putting on a ported blower housing and northstar throttlebody. They got it up there and did 5 runs. The guys told me it was running really rich because the new maf so they dropped the AFR from somewhere in the mid to upper 12s down to high 11s. They then adjusted some spark advance timings, but, as the dyno sheet shows, nothing actually made a difference, even the AFR change. They didn't seem to worried about why that was, but to me it sounds like I have something restricting me. Anyone got any advice? The one thing they suggested was maybe a clogged cat, but its a two year old ZZP high flow cat so that seems strange if it was that.

For reference, my current mod list is
-ZZP headers and 3" DP
-Custom 2.5" catback with glasspacks
-1.9:1 ZZP rockers
-K&N CAI
-Autolite 104s
-180 Tstat
-3.4" Pulley
-Ported blower
-Northstar TB

Dyno sheet

 

I'm not understanding this one. If a new MAF was put in, the car should've been tuned to the new MAF before any pulls were made. Was it?

This is also confusing. 12s are leaner than 11s, so they were adding fuel, not taking it out.

TBH I wouldn't have even completed a pull in the high 12s, that's getting way too lean. High 11s sounds like a perfect place to end up though.

What did they adjust it to / from? Any KR at all?

If they only adjusted a couple degrees (or if they're adding timing and its already 20+), then I could see it having no effect.

240 whp isnt all that bad really, that's nearly 300 crank. For a handful of bolt ons, you're doing nicely.

I do agree it should have more in it though - why the 3.4" pulley? If the timing they ended with is pretty high and theyve still got no KR, I think youd be best off dropping a pulley size (and a bit of timing) and trying again. The pulley size is the #1 thing dictating airflow (and thus power).

 

Yes, they tuned it for the new MAF first

I don't remember the exact values the guy tuning it said, I can call them tomorrow and ask if they would be useful information. I do remember him saying they tried timings from around 10 to 16 I think, I can get exact values tomorrow as well if need be. There isn't any knock.

The 3.4" Pulley was already on it before the ported blower and TB, I asked ZZP about it getting a smaller one and they said it isn't going to need anything smaller given the mods I have on it with 91 octane so I didn't bother buying a smaller size. I do know that I am hitting about 11 PSI of boost, is that not about at the upper end of the efficiency range on these blowers? From what I understand of this anything much higher than 11 PSI is just going to reduce my efficiency and not net me much gain.

Oh I should also mentioned that when I talked to the guy doing the tuning he said that it was nice to see that my boost kept climbing throughout the pull and didn't drop off. I don't know if thats helpful info or not.

 

Surprised at 2 things here:
1st that there wasn't any measurable power change from 10 to 16. You certainly should've picked up something there. I wonder if something else was going on like heat soak or something that was negating the power gains youd normally see from adding timing. Were the runs pretty close back to back?

2nd that they didn't push timing further if they had zero knock. I certainly like to go back and set it to a known safe level at the end, but until you push it far enough to see some knock, you dont have any idea how close to the edge you are.

I'm just thinking that even more timing would've helped pick up more power. I would've tried at least 18 and maybe even 20. I'm also thinking that if you got that far and were still clean on knock that it's a sure sign that it's time for a pulley drop.


I think they're spot on for most setups. They'd rather suggest something thatll be knock free in 99% of cars rather than something thatll only be knock free on a small minority.

I do think you're close to being able to take that next step in pulley size though, even if just to a 3.3 or 3.25". You've got some good mods, and you seem to be running totally clear of knock. It does seem like you're more lucky than most, especially on 91. But again it depends how close to the edge you are.


I wouldn't pay too much attention to the boost number though, it varies so much with other mods. Itll naturally climb and fall as you work through all of the mods on the path to a maxed out setup (not saying that's your goal here of course). The biggest indicator of efficiency is the blower speed (pulley size). Certainly your blower is more efficient on a 3.4" than someone with a 2.55", but that blower speed directly dictates how much air the engine is getting and someone with a 2.55" is moving a lot more air (although itll be far hotter). All of the big power M90 cars are running sub 3.0" pullies.

 

Hm, I'll have to ask them tomorrow about what specifically they did. I don't know the process they went through when tuning it, they may have raised the timing and saw some knock so they dropped it back down, I don't know. They did all 5 pulls within about an hour, don't know if thats frequent enough for heat soak or not.

If they tell me they never saw any knock I'll see about getting a 3.3". As for why there was no power increase, I still am not sure on that one. Maybe it'll make more sense when I get the actual numbers they tried as far as AFR and timing is concerned.

 

So update, I talked with the guy who did my tune yesterday and this is what he did

• He said the AFR coming in was 10.1-10.3, so he tuned it on a taper starting at 12.0 and ending at 11.7 WOT
• Timing coming in was 15, he tried timing values anywhere from 10 to 18.5
• He said he couldn't read if there was knocking, however he said the timing was following the target pretty closely without any dips so he doesn't believe it had any knock

It sounds to me like I should be okay with going down to a 3.3" pulley and having them tune it again. As for why the power and torque curves stayed identical throughout all that, I don't know. It doesn't have anything to do with the fact that the PCM I have is a canned tune, does it?

 

That makes more sense with your original comments. I'm not super surprised you didn't see a big change in power from this change. Low 10s is pretty low but isnt into 'absolutely drowning and tanking power' low. You're just having less wasted excess fuel going out the exhaust at WOT now which is a good thing.

This part is a bit odd. If it was 15 on the first pull with no signs of knock, I wonder why they'd reduce it at all (especially all the way down to 10)? That is good to hear they tried running it higher without issues as that let's you know you've got some margin for a bit more boost.

Definitely puzzled why the cars output didn't change between 10 and 18.5 though, there should've been a noticeable delta between those two.

That's pretty concerning, any idea why they couldn't read it? That's a pretty standard parameter in either HPTuners or DHP PT.

What scares me here is if a professional tuner isnt able to get a reading at all, maybe the sensors are messed up? Definitely need to do a but more digging here before dropping pulley sizes. Proper operation of those sensors is critical to keeping the engine alive at higher boost levels when something doesnt go as planned (bad batch of gas, higher than expected load, etc).

It's not really a canned tune anymore if they're messing with spark and fueling, it's a custom tune where they started with a base map closer to the end goal (rather than tuning from stock).

 

Yeah I'm not sure why there isn't a change either. I believe he dropped it down to 10 to see if there was something restricting me from making more power. I think he was looking for the power curve to drop slightly, and have sort of a ceiling that it hits as he increases timing back up. Doesn't seem to have one unless the ceiling is lower than expected and the timing would need to drop a long ways before any power drop-off occurs. Just a guess though.

I don't know why they couldn't read it. I called this morning and asked but the guy who did the tune was busy and I was told they would get back to me. I haven't heard anything back about why they can't read knock. I am due for a service soon so I might ask them to check the sensor for me while its in there.

 

Definitely worthwhile to look into. If it is a maintenance issue, now is a lot better time to find it than when you're out pushing it hard.

 

So I think I found out why they were unable to read KR when on the dyno. The shop was also using HPT, and I recently ran into the issue of VCM Scanner PIDs disappearing when I hit record, one of those PIDs being KR. The fix was to use the latest beta version, something they probably didn't try while it was on the dyno. So it seems like the issue was just a software issue, because using the beta version of VCM Scanner lets me read knock correctly.