VersaTune User Forum

Greetings all,

I have the following mods to my MS6:

- Built block (Manley H-Tuff rods and pistons, and supporting components)
- HTP 3.5" intake (recirculated w/ honeycomb air straightener)
- Turbosmart Plumback BPV
- Corksport CST5 turbo (internally wastegated w/ base 14 psi springs installed)
- ATP catted downpipe
- Corksport FMIC (the newer revision)
- Corksport CBE
- Corksport HPFP internals
- Bosch 3.5 Bar MAP sensor
- Grimmspeed EBCS (run in 3-port interrupt mode)
- Fuel: E10 (standard 93 octane)
- Stock manifolds (i.e., completely stock intake w/ VTCS and exhaust)
(For brevity, my mod list only contains pertinent components related to ECU/engine tuning)

I'm proactive with the car's maintenance and check things regularly (i.e., fluid changes, checking plugs, no check engine lights, compression and leak-down tests are excellent, etc).

My question is: Would anyone know how much I'm restricted by the stock manifolds?

During my research on the stock fueling setup, I've found that it's limited to around 350-370 whp. I assume these figures describe the MS3's FWD drivetrain losses, running higher octane fuels (i.e., E30 or higher), max effort/aggressive tunes, and better flowing setups (i.e., non-stock manifolds), etc.... So I expect lower figures for the MS6 due to its higher AWD drivetrain losses.

After engine break-in, I begun tuning and found that I'm running out of IDC headroom (reaching ~95% in the upper RPMs). So I'm limited to around 300awhp (obtained from VirtualDyno). Also, to achieve this, I have to (and can run) absurd amounts of timing to get to that point (see the attached log). When compared to other similar vehicle build logs, MAF g/s seems high in comparison to the power it's making (in addition to timing adv). I figured the timing gear on the crank pulley might've slipped and retarded global timing. I ended up double-checking timing multiple times with no issues found. I'm curious to hear any other anecdotal experiences from others with tuning experience on this platform. I have a JMF V2 waiting to be installed and begun preparations for its install with standard 8-port injection via Split Second Controller. I also plan on ordering the Corksport exhaust manifold as well. So it will be interesting to see the differences between the two setups.

Lastly, considering the log I've posted. I've reduced timing and added fuel to address the knock in the upper RPM range. It's not consistent on a per-run basis, but I'd rather be safe than sorry. Also, I'm doing another MAFCAL to address the deviation between observed and desired AFRs.

Any feedback would be greatly appreciated.

ZeroDCX wrote: ↑July 6th, 2025, 10:44 pm My question is: Would anyone know how much I'm restricted by the stock manifolds?

Yes, I happen to know.
Stock intake manifold with the VTCS on: 450-470bhp max.
Stock exhaust manifold: about 510bhp (I made 509bhp on 31.5PSI, and at 36PSI I was making only 525, and eventually cooked injector on cylinder 3).

Now I upgraded the exhaust manifold because as we know it's the main reason these engines let go on cylinder 3 in various ways, but the intake manifold is the stock one, slightly ported, VTCS off of course, EGR still on, and I've stopped chasing for more power because overpowering a FWD is fun up to the point it can still be controlled, but not so much beyond that.

An upgraded exhaust manifold will add some more power at the same airflow and timing values just because the engine doesn't have to work against itself, and the upgraded intake manifold will lower the turbo effort. So all these mods count.
And of course with aux fueling you can go a lot higher - but how much higher depends on the fuel and aux fueling setup:
- if you run pump gas through both you will see a cap around 500-550 depending on the fuel and other things (turbo, exhaust, weather);
- if you run an ethanol blend from the tank through both then it really depends, but even with with E30 you may max out that turbo;
- same thing as above if you will set your PI to use a separate fuel cell and you will run E85/E100 or methanol from that one (if you run methanol make sure the PI injectors are compatible with that, ethanol and methanol are different beasts).

P.S.: just checked your log and the timing you're running is a tad under what we run with WMI. I tuned a lot of cars and I've never yet encountered one to run 14+ degrees of timing at 6k rpm at that air flow, and definitely not 12 before 5k rpm. Also at that airflow you should be a bit above 300awhp. So as you guessed something may not be quite right...