Magnuson Supercharger Mega Thread for 16+ Tacoma - Unboxing, Install DIY, Dyno Video

Our compression ratio for the 3.5L is 12:1. Literally zero room for error.

 

I just don’t see how. It’s pneumatic damper that’s all. There is absolutely no way it can influence AFRs once the bypass is closed. It can’t introduce unmetered air and it does not increase max boost. So where is the extra air coming from to create a sustained lean mixture? There’s got to be something else going on that caused 13:1 on your test.

 

Bro… you gotta trust me on this one. Will show you screen shots of the AFR gauge. I have a manual trans so I can go max throttle in any gear and any rpm. Magnuson tune never accounted for the restrictor to be removed… Period. Ever wonder why it makes such a big difference in throttle response. Its like installing a smaller pulley. I literally threw mine away after I installed the supercharger. Had to dig through the garbage when I found the AFR discrepancy. Now AFR’s are consistently 11.9-12’s in the same RPM range even with the 87mm pulley.

It’s ultimately up to you guys to do whatever you want with your trucks. But after running a bunch of tests on the street and dyno my restrictor is back in place. Unmodified.

 

12:1 is the static compression ratio if I remember correctly. What needs to be watched is the dynamic compression ratio and cylinder pressure.

 

it makes such a big difference with throttle response because that is the only thing it can possibly affect. You can zip tie the bypass closed if you want even better throttle response with terrible gas mileage. It still won’t make it leaner, but it will make the intercooler work overtime.
I have a manual too.

 

@mZiggy
What’s your opinion on this little friendly debate?

 

@OpelGT Here we go. Screen shots. Restrictor out. 90mm stock pulley. Magnuson tune. It runs lean in more than the stated range. Note the 13.3 right before 6k redline.

 

I think you're both right. The physics of the function of the bypass supports the fact that there shouldn't be any effect once closed, but based on what we've observed while testing, I'm also led to believe something else is going on.

This is either compounded by or due to the fact that I've documented on both NA and FI applications, the passenger side bank runs leaner than the driver side.

There's multiple ways to go about accounting for this, and each warrants its own line of testing before deciding if it works in multiple scenarios and climates or not, and if you want to use it. For example, I recently successfully made the ECU target richer than 11.9AFR across both banks as low as 27-2800 rpm in 72F weather. Perfect! Anyone who was irresponsible would say sweet, we're done here. But then it ran way too rich in 15F weather and was choking out the system. Not perfect.

So I'm still evaluating other similar options that work across multiple climates and don't send your fuel economy into the single digits.

 

@OpelGT The very next morning Feb 7th. Screen shots. 90mm pulley stock tune. Restrictor back in per @mZiggy ’s solid recommendation. He thought it may be messing with AFR and sure enough...

Less power but clearly safer AFR on the stock Magnuson tune.

 

For those of you like me that chucked your restrictor or modified it you can purchase one brand new for $11 + shipping from superchargersonline. Email David. Let him know you need the brass bypass valve restrictor fitting for the Magnuson TVS1900.

david@superchargersonline.com

Again, I would not remove or modify this piece of equipment if you are on the stock tune regardless of which pulley. The discrepancy will only worsen with the smaller pulleys.

 

Weird. Since it’s not physically possible for the restrictor to directly cause a lean condition, but we have two tuners who have data showing otherwise that means there is an indirect consequence of the restrictor removal we are missing.

My vote is turbulent flow issue possibly caused by uneven exhaust scavenging due to slightly different exhaust designs for each bank. The intake runners on the magnuson unit are less than ideal and probably compound the issue by shoving a higher fraction of air into the already higher flowing bank.

but here’s the part where my fluid dynamics classes fail me. So the bypass closing more quickly could change the airflow and cause a change in the path the air takes IE the SC could shove more air into the leaner bank. The question is can that brief blast of turbulent flow create a condition that causes it to be maintained under sustained throttle? With water this can happen, but I can’t remember if this is true with pressurized air. I guess it probably is since they are both Newtonian fluids. We could test this by lightly rolling on the throttle and seeing if AFRs differ from slamming the throttle before a sustained run.

The only other idea I have is that there may be a flutter in the bypass valve without the restrictor. But this would create a “boost leak” and should make it richer.

TLDR I don’t have a freaking clue. 13:1 is good enough for me. I trust direct injection lol.

 

The one thing I’ve learned about these trucks is the more we think we understand and have them figured out, the more we find that doesn’t make any sense and sends us deeper down the rabbit hole lol

the only thing consistent about these trucks is inconsistency.

 

@mZiggy and other testers/tuners on this forum myself included have tried to make sense of certain aspects of this ECU and quite frankly it is complicated AF. The reasoning for removing the restrictor causing leaning is unclear. It probably throws off the air load calculations post MAF and throttle body.

 

So what safe AFR range are we looking for with the stock Magnuson tune?

 

I also have a manual with the restrictor removed. I have not heard any audible detonation, but I'm not saying it's not happening. I still don't have my boost/afr guages in so I'm blind to issues..... So I'm interested in the outcome here.

 

Since you're in Wisconsin, it's likely quite cold there and so you are likely seeing enrichment anyway with the lower temperatures

 

Ahhh, yes. That makes perfect sense.

 

11’s to 12’s. See screenshots above.

Hey guys, just to clarify I never said I heard ping with the restrictor removed. As I mentioned earlier, running sustained 13’s AFR during towing in high gear low rpm puts the truck at high risk for ping to occur. Transient brief 13’s for a second during transitions? Probably not a big deal. Going over a mountain pass in boost with significant load at 2700-3000 rpm with AFR in the 13’s sustained? Might want to check those plugs after.

Relying on the trucks knock sensors and the ECU to pull timing and enter limp mode is one thing but it’s not fail proof. The ECU will definitely pull timing where it can. I have heard the audible ping and felt the truck pull timing with the 84mm pulley on this truck with the Magnuson tune. The strange thing? No CEL or limp mode.

The data is posted above. You guys have been warned. Do what you will with the information and boost on!

 

Please bear with me here cause I’m just starting to study and learn about air fuel ratios, but what determines these numbers? I’ve read the ideal ratio for a gas engine is around 14.7. Does the ratio need to be lower because it’s boosted? Is there math involved to get these values?

Just trying to wrap my feeble mind around this stuff (as I dig out my restrictor from the BIG BOX of other Tacoma take offs I’ve got stashed in my garage attic).

 

14.7:1 is the most efficient ratio for fuel economy and emissions under light/normal driving. Maximum power is generally achieved around 12:1. The more more lean the mixture is, the more heat it creates, which is not good under any circumstances and even worse when boost is involved.

Closed loop will keep your AFR's around 14.7:1 under most driving conditions...under heavy throttle it will switch to open loop which richens up the mixture.