944M3

I'm ready to purchase a MAF, leaning towards Vitesse V-MAX+. I decided against standalone as I just don't have the time for the learning curve. Also, from the reading I've done it seems a MAF might be better (vs MAP) for everyday driving in a city. But again, the big factor is plug and play. I totally understand a standalone will give more options to play with but I don't have the time or motivation for it.

So my question is, can a MAF car still benefit from a professional tuner? I know every car is different so chip can't be perfect for every car, but does a MAF chip have enough "adaptability" in its tune (measuring air) to adapt to the specific engine and components (for example my k27/6 turbo with stock exhaust and rebuilt head) and thus not really need or benefit from a professional tune on a dyno? Hope the question makes sense.

And I might as well ask this question. If I'm willing to pay for a tuner, do I even need a MAF? Would I get the same result tuning on a dyno with a stock AFM? I understand that by installing a MAF the performance is better than AFM using a stock DME tune from the factory (stock tune being the key) because the AFM is more restrictive to air flow. But what happens if the same car is tuned on a dyno with the stock AFM, would you get the same results by adding a MAF and not tuning? Which brings me to my original question, would a tuner make a MAF equipped engine even better than an AFM tuned car. Again, hope that makes sense.

For context, I'm not looking for more HP (but of course welcome), its my daily driver that I track maybe once a year for fun. I'm looking for more down low torque and drivability around town. I currently use Rogue's A-Tune (still using stock AFM), which is good but looking for even faster spool up and low end torque, and sure, more fun.

Like most of us, these are questions that rattle in me brain (when I should be thinking of more constructive things), I need answers lol I appreciate any comments.

V2Rocket

Vitesse supplies a very good tune with the MAF and can adjust the tune to any modifications from their spec - he would be your tuner.
He does have legendary customer service, which is nice.

No, you will never get the same results with an AFM as you do a MAF or MAP. More airflow, almost 0 airflow restriction (vs a lot on the AFM), more precise measuring of incoming air. MAF/MAP are better in every possible way than AFM. A car with a "stock" tune and a MAF will make more power, more torque, boost earlier, and be more responsive than an AFM-equipped "stock tune" car, because of that airflow restriction.

Someone may come along and say "I made XYZ HP through the AFM" and yes you can make 400hp or whatever at peak, but the MAF car will have more area under the curve and will be faster and more fun to drive.

Mike Goebel

It makes no difference. There are differences but it will make no difference in drivability or performance.
Yes but if the dude selling you your kit has already mapped the system for an engine with your build its probably not necessary. You've got a stock engine, you're not trying to run it on the ragged edge of exploding.
The engine is not tuned by measuring intake air mass flow. It's tuned by measure exhaust A/F or Lambda and adjusting the fueling and ignition timing requirements. So as far as adaptability, typically the engine control system would have a self learning feature that would require an lambda sensor in the exhaust and adjust the fueling closed loop. But these self learning feature are not 100% bullet proof.
The stock AFM for practical purposes can't be "tuned"
You will gain some HP with the MAF simply because it's not as restrictive. There are some HP increase values floating around on the internet but I have no idea of their validity. The Rouge A-Tune is a solid plug and play system. You are going to be messing with stuff with any other system you purchase.
There is nothing more important in the World than pondering anything about the 944.
Mike G.

Dan Martinic

I have never driven a 951 with anything but a stock AFM. But, I can tell you something I've personally experienced:

My buddy in Ottawa had a bone-stock 951 with an older MAXX chip and the "Lindsey Boost Enhancer". I was so impressed with its response, I sourced a Rogue A-Tune and similar ball & spring psi valve to use as a "boost enhancer" like the Lindsey unit for my stock 951. I also upped the total boost on my car to 15 psi using a manual boost controller. My buddy had the stock CV.

The chip and "boost enhancer" is a very dramatic combo. The A-tune chip alone isn't as dramatic without the boost enhancer. And unless you're pushing the pedal down low a lot, increasing total boost isn't really that big a deal for regular daily driving (fun for very brief pulls though but who drives around all day like that?)

Before dropping lots of $$ on complete system replacement, buy a cheapo ball & spring psi control off Amazon (or the LR version which comes with the fittings) and plumb it off the banjo bolt line from the intercooler. Before installing, set it with a bicycle pump to open around 10psi. Your boost will spool up much quicker and the A-Tune chip will keep air/fuel ratios proper and safe. You'll also have the "half-throttle / full-boost" thing going on which is very effective in daily driving.

Enjoy that for a while then when you get used to it--as we all do with any upgrade--you can replace the whole system with a MAF etc. Might as well enjoy upgrade thrills in stages; the effect lasts longer

EDIT: PS... be super sure your BOV is working properly. I drove for years with a degrading & leaking valve and the loss of performance was so gradual that when I replaced it, it felt like a new car. Can't believe how bad it is if that thing isn't perfect

944M3

Thanks for the comment Dan. Should have noted that I'm using LRs MBC with a Tial 38mm dual wg with a 1bar spring with an Evergreen k27/6 Raptor turbo, also did venturi delete. (I've toyed with the idea of just using the spring to hold boost, which should be 14psi). The engine and head has been refreshed and sealed, also using new hoses and vacuum hoses and a new Forge BOV. I think I've fixed all exhaust leaks.

Before installing A-Tune, I used Autothority chip with banjo bolt. It was actually good on hard pulls, really pushed you back to your seat. The A-Tune feels a little more tame than the Autothority chip. I haven't really figured out why that is. Don't get me wrong, the car is smooth and its fast but just not "violent" like the chip was.

Correct me if I'm wrong, but using the MBC and dual gw, the LR boost enhancer wouldn't do anything for me. That is my understanding anyways.

Mike G., my understand is that an engine using a stock AFM can still be dyno tuned with improved performance results such as torque. I've spoken to tuners who have done this. Which is why I ask, if a MAF is really needed, Just trying to eDumacate myself

Mike Goebel

So are you saying that you'd remove the A-Tune and try to tune with the AFM? I'm pretty sure doing that would never be as good as using the A-Tune. The A-Tune is the best non expensive way to go.

I had considered a VEMS but I'm not sure that system is really as easy as it is stated PNP ???

Mike G.

944M3

Yes, that is what I'm saying. Basically tuning a stock engine on a dyno by a tuner with expert knowledge of 951 engines.

But I agree that the A-Tune is probably the cheapest way to go. I believe a rolling dyno tune can start at $1k and goes way up from there. But if you ignore cost, would a tuned stock engine perform as well as a car with just A-Tune or MAF. And to note, I'm not talking about making it a race car with a tune or a MAF. I'm just talking about making the car feel more responsive down low with faster spooling. And I'm fine if the improvement is only felt on the butt dyno

Tom M'Guinn

Right, a stock 951 with AFM 'can' be tuned by anyone set up to burn you a chip. Finding those people can be a challenge, which may be what Mike meant, but they are out there (e.g., Edd China had a place dyno tune the 951 they restored on Wheeler Dealer.) Most tuners can pick up 50hp +/- on a 951 if going from factory chips and adding boost control. That said, the various chips out there cost a fraction of the cost, and get you most of the gain. I ran the Autothority chips with banjo bolt for a while thought it was great honestly. It gives a huge shove, drives like stock, passed smog, etc. I think a lot of the other chips makers tried too hard to get a higher peak number, or just weren't as good at tuning. If you still have the Autothority chip and banjo bolt, consider adding a Tial dual port wastegate and deleting your catalytic converter (if legal where you live). The combo of those two things can further improve the sense of low end response. I'd say the VR MAF can enhance both low end torque and drivability, but not sure anyone would spring for that system just for that reason. I'm a huge fan of the VR stuff, but you buy it to make power. Slightly improved drivability is just a nice perk. VR also has an AFM chip, which I ran for a brief time. It felt about the same as the Authority, but the AFR curves on the dyno were much closer to ideal across the board. My car would dip into the mid-10's on the Autothority chips, not matter what I did to negate that.

There is no self-learning on the 951 unless you go with a stand-alone that has it. There is closed loop feedback (knock, O2), but it just reacts to what it's seeing at the moment, not remembering and adjusting the tune as it learns. The nice thing about AFM and MAF based systems is that they can accommodate changes without re-tuning (e..g., more/less boost, cams, exhaust, etc.). On the speed-density systems run off a MAP sensor, you need to adjust the tune for such changes. Regardless if it is an AFM, MAF, or MAP, the maps are based on air mass (along with other inputs), and that tune is then adjusted by tuners based what they see re AFR, knock, HP/torque, etc.

Mike Goebel

Speed-Density does accommodate for different conditions. That's what makes the A-Tune such a great little system, the addition of the MAP sensor. One day run 14 psi next day 18 psi.

Mike G.

944M3

Thanks for the comments Tom. Yes, I saw that episode of WD.

I might actually agree that the Autothority chip felt better than A-Tune. Problem is that I had to upgrade my DME to 28pin for the A-Tune chip. I still have my Autothority chip but its a 24pin chip, which I believe won't work on my 28pin DME (haven't actually tried it). But yes, I am already using a Tial dual wg. I do have a sport MagnaFlow cat, which theoretically should flow better than a stock cat. But I never dyno'd to verify. I'm now actually considering finding a 24pin DME I could borrow just to test the Autothority chip again. I have a wideband O2 sensor installed and would be able to measure my AFR.

Perhaps the Autothority chip works better with the k27/6. I purchased the car with none of its history so I don't know if the chip came with the upgraded turbo as a package. The turbo was from Powerhaus but has since been rebuilt by Evergreen as a k27/6 raptor.

Per your comment "Most tuners can pick up 50hp +/- on a 951", it seems that a stock dyno tune would outperform the A-Tune as I don't think an A-Tune comes close to adding ~50hp, by itself anyways. Or course, at a much higher cost.

Mike Goebel

Air mass flow is what determines the HP in a nut shell. Since your using the AFM with both systems there is no reason that one would be an advantage other than the A-Tune allows you to make changes without having to re-map the engine. Plus there are probably some safety measure designed in with the ability to read the manifold absolute pressure. Maybe the hard mapped chips have more aggressive ign timing than the A-Tune?? IF the A/F is that same between the two systems, which I'd guess its very close then the HP is basically the same.

Mike G.

divil

So the A-tune system is speed-density? I thought it used the air flow meter, and the MAP sensor is just so that it knows the boost level?

Tom M'Guinn

In fairness, the 50hp I mentioned comes mostly from boost. How much boost are you running? Do you think the car is less torque than typical 951's are are you just trying to add some low end?

Mike, not sure if we're saying the same thing, but being able to make changes without re-tuning is not unique to the A-Tune. Same is true of the VR MAF system and (for the most part) for aftermarket chips that use the AFM, within reason anyway... I go from 12psi to 22psi without changing anything else on my VR MAF system. The AFRs remain spot-on, and the tuning maps reduce timing a bit as the boost builds.

Tom M'Guinn

+1

fast951

So many questions, many good responses and some not so accurate ones. I'll attempt to answer all the questions, hopefully it'll give you a better idea of what suits you best.

With the stock turbos (k26/6 and K26/8), the turbos are your HP limiting factors as they do not flow much. The stock AFM supports the flow of either of the stock turbos. As long as the car is fairly stock, except for an exhaust and a wastegate, a performance AFM chip running at 15-16 psi and a 3bar FPR will be your best bang for the $. You will see 40-50hp gain from the added boost and the proper tune.
The same setup (stock turbos) a MAF will yield more power across the power band (less restrictive than AFM), but your "peak HP numbers" will not vary much (around +5-7 RWHP)as the turbos are limiting your peak number. With the MAF the car will be more responsive, so driving characteristics are improved.

When you upgrade your turbo, you may exceed the flow capacity of the AFM. That's when a MAF is a must! Of course with the larger turbo additional air flow you need more fuel (injectors and FP).. A proper MAF can support lots of HP, yet maintain crisp response and enhanced drivability. As far as tuning, I find the MAF sensors are more accurate than the AFM (especially the 30 years old AFM). With accurate MAF sensor, the tune will be more accurate.
Not all MAFs are the same, some are more accurate and not as noisy as other styles/types of MAF. I tested many types and brands of MAF before selecting what works best.

In the old days (pre 2007), the AFM chips and MAF tunes never operated based on actual boost, as the DME never measured actual boost. In 2007, I introduced boost (via a MAP sensor) to the DME. So ignition and fueling were based on air flow (MAF) and actual boost.
By introducing the boost/MAP, the same tune would work with various turbos, as the spoolup characteristics of the turbo (boost) is captured and used by the DME. The AFM chip supporting the K26/6 or K26/6 did not need a MAP sensor as the turbo spoolup characteristics are well known.

When tuning a car, we take into considerations many factors. Reliability is always number 1!!! Performance, safety, driving characteristics and flexibility are all things we consider. For 99% of the cars our basic MAF tune is all you need. Over the years we captured lots of data and we constantly improve the tune based on the above parameters (reliability, performance, safety, driving characteristics and flexibility).
Some cars running higher compression, aggressive cams.. do require a custom tune to support the unique items on the car. We have tunes to support many combinations. In some cases, where the modifications to the engine are so unique, a custom dyno tune may be needed.

No two engines are 100% identical. I know our tunes get you 95-98% on target. If you are racing, and you require the last few %s out of your engine, then a custom dyno tune will do. We do offer a Piggyback to tailor the tune to your car and to dial it in 100%. However, with 1000s tunes under my belt, I can assure you (with a stock engine internal configuration) our MAF tune is about what most people want/need.

All of our tunes have a margin of safety built in. We do offer aggressive tunes (less safety more performance), but such tunes are best left for the race cars where fuel octane and running parameters are controlled much more than street cars. Our MAF tunes do support pump gas (91 and 93 octane), race fuel and E85.

The bottom line, with a larger than stock turbo, the AFM is not the proper sensor to use. Fine tuning to match your car 100% is obviously better than 98%. However, we are not talking about huge gains here and $/HP is something to consider.

Define your long term goals, select a product you will not outgrow down the road. And make sure whoever you purchase from has a good track history and stay away from the "flavor of the day" products. Do it right the first time is always less expensive and more enjoyable than the second time.
Whatever product or vendor you go with, make sure your car is in a good running condition before upgrading.

Hope I was able to clarify a few things for you.