Out of curiosity I did a few quick pulls today w/ no filter or screen at all. Was expecting to pick up a bit over running just the screen, but there was absolutely no measurable difference in terms of peak boost readings.

I went back to look at what boost you were seeing. 9.5 - 10 psi. As Cupcakez mentioned and as I think Topz would say, that’s kinda low for not running a filter. This could explain you are not seeing an increase in your last post. Your SC might be pulling in more air, but at what would be 10 psi and above it’s just escaping from somewhere?

Considering some of the recent discussions, it seems like my boost has been a bit (~3#) low ever since I installed the SC earlier this year (Aaron's full kit w/ 9# pulley & Si trim). So i thought I'd take a look at my last datalog that I did for Seb from a few months ago. I charted Manifold Absolute Pressure v RPM. As you can see somewhere around 6700 RMP it starts to flatten out. Is this normal for this setup, or should it maintain basically the same slope all the way to redline?

Mine starts to level off like yours. This is Topgunz full kit, stock pulleys, stock filter, long tube headers. Hits 12.76 psi.

Thanks for the confirmation. Wow, your car really makes a lot of boost w the stock pulleys and especially since u hv LTH which generally reduce boost due to their better flow characteristics.

Yeah, I don’t know why, and not convinced it’s all good. Tuner says might be due to his cam tuning. I would agree, but can’t tell and haven’t dynod yet.


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Hmm. That makes a lot of sense. And I think u may be right in that it may not be good, as boost is, in a way of thinking, the opposite of flow. So if the exhaust cam timing is actually allowing less flow, that could equate to more boost. Just like an exhaust restriction.

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As for mine, I guess I'll look into doing a boost leak test.

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Honestly I still have the same problem as you too. I can tell Sebastian almost seems a little frustrated, we've had to go down in timing from the base map to prevent ignition correction (usually it's the other way around, lol). He's brought up e85 a couple times now but unfortunately it's just not possible in my area, I would have to get barrels delivered, and I daily drive the car for the most part so it's just out of the question. The car goes on a dyno on Friday however I honestly don't expect it to make much power with the amount of timing it is running, I'd guess 450whp max. Sucks because this kit has so much potential just to be handicapped by bad availability of fuel.

So your tuner is frustrated, and my tuner is "yay! more boost". Hmmm. If its honest boost, and not just some bad restriction, or cam issue, then it should be a good thing. People normally have to buy a different pulley to get more boost, and the result is MORE power, not less. So I wonder why he's frustrated. Because hes pulling timing only after 10 psi to keep it from knocking? And pulling so much that he feels it negates the increase in boost and ultimately will make LESS power?

Has Seb suggested getting a knock sensing tool to figure out if you're getting REAL knock? The tools from Plex tuning, Tuner Nerd, etc ? Im considering it, because I think my car too was correcting timing more than what my tuner was expecting from my setup. An maybe my tune also has pulled timing compared to other tunes, Im not sure. Update us with the dyno!

I definitely over exaggerated Seb being frustrated, it's more of a joke as to how much effort has gone into trying to get the timing to make sense. Really I'm not sure what's going on with the car yet. I've done close to 20 data logged WOT pulls now, AF/R is good, boost is good, just timing/knock is being seemingly strange. I've used an octane booster (boostane) at a pretty decently high concentration and it made no change with the ignition correction. At first it seemed like maybe the knock sensor was possibly picking up some false positives, but when tested with a low timing map the ignition correction almost entirely went away. Most of the ignition correction that happens is around 5k rpm, before full boost. The knock sensor seems to be the most happy around 9 to 10 degrees of timing.

The reason for the low dyno estimates is because I've actually already had it on a dyno so I know ROUGHLY what it will be making, but for various reasons I'm getting it re-done at a different shop this time. It was a half assed dyno day type of deal where they didn't actually log a complete pull, graph cut off at 6,800rpm.

I feel u on the availability for fuel man. In the same boat in our area. E-85 is definitely off the table here due to our extreme humidity. We also only have 91 octane as the highest fuel source at the ⛽️.... even worse news is our race shop that usually ships in race gas/higher octane fuels from VP Racing no longer brings in VP products due to their supplier no longer being a VP distributor....so now the best grade available to us is F&L 100 Octane. Haven’t used this fuel source yet as I’m still doing research on it. Some of the guys that I know who switched out their tunes from VP MS109 to the F&L 100 have seen a 10-15% power loss.

Is water/meth injection an option? One of my customers is making 560whp on that without a RFS.

https://i.imgur.com/fAIX2rn.jpg

As suspected, the map sensor seems to read boost a little high, when running a vacuum line to the dyno it reads 10 to 11psi. Pretty happy with these numbers, right about what I expected with the crap fuel I have. I think I might try an ethanol blend later on, I don't like the idea of running straight ethanol considering how hard it is to get in my area, but that's another project for another time. I do still suspect something might not be entirely correct with my knock sensor considering there was no effect when I added boostane, so still need to look into that.

Thanks for posting info. Is it normal to have that big of a power difference in runs that close together time wise? I assume nothing changed.

Red was 4th gear, blue is 5th. Forgot to mention that, my bad.

After some feedback from Seb, I decided to take another look @ my most recent data log. I converted the manifold absolute pressure (bar) readings to PSI and charted them again. So it looks like (according to the MAP sensor) i've actually been making around 10 psi @ 7k RPM, although my boost gauge has been showing a peak of only about 7.7 psi. Yay. Much better to have a low-reading gauge than to actually be not making the desired boost / power.

I made a short video giving a small taste of what it's like driving with this kit. Probably best viewed on a computer due to the detail of the data.

https://www.youtube.com/watch?v=Uz6SW9joFfQ