fast951

We just did, and the allocated components were exhausted much faster than anticipated.

Porsche-O-Phile

Undecided as yet. . . I will say any Vitesse stealth MAF kit would certainly get my attention (and money) on the day of its release - assuming of course I didn't already have a MAF kit at that point. The clock is running. . . I'll only be able to hold out for so long. . . *tick* *tick* *tick*

Here's one free potential customer perspective for both of you guys (and others) to consider:

- I want MOSTLY plug-and-play capability with the products I buy. I am certainly willing to do SOME tuning and customizing/fabrication, but I don't want to either spend hours and hours (and hundreds of dollars) on dynos to do tweaking in order to get results. The out-of-the-box solution should be pretty close to perfect - as close as could reasonably be expected. FWIW it sounds like both products (and Lindsey's) are. Tuning should be just that - tuning.

- I don't want to be a software engineer. I've always liked the fact that these cars are still understandable from a "carbuerators & points" kind of mentality. Yes, they're computerized, but the level of computerization is very first-generation and conceptually simple. "Modern" cars involve way too much cryptic crap in black boxes and tuning/racing becomes more of a battle of "techno-weenie" geek ability than understanding principles of physics. Like I said, I'll certainly perform basic tuning, but if it requires hours of programming and re-mapping to get it to work well, it becomes something that's really not all that interesting to me anymore. . .

- Stealth! This has probably been beaten to death (and yes, I know all this stuff is "for off road use only" ), but the stakes are simply getting too high to get busted with ANYTHING that looks out-of-place under one's hood anymore. Without getting into a discussion about how it's best to not draw attention to onesself through street driving technique, etc. I'll just say that a good, stock-ish looking setup is HUGELY desirable. There's a big market for it. Hell, I've even considered trying to get something like Bill did with his "stealth MAF" install produced and sell it myself, but I don't have the time to put into it. Suffice to say, an off-the-shelf solution like Promax is offering is pretty damn inticing. . .

- Reliability. One of the strengths of these cars I've always believed is how robust they are. You can boost the crap out of them by 25%-50% above stock rating, whallop the sh*t out of them at the track all day and they'll beg for more and still let you drive them home in comfort. That's pretty nice. A MAF or other piece of equipment for performance is ALWAYS a trade-off to some extent between reliability and raw power, but for one, I prefer to get as much of both as possible. The best way I've seen it put is "FAST/RELIABLE/CHEAP - choose any two". I suspect that I, like many others, are willing to pick "fast" and "reliable" even if it's not necessarily cheap. Products costing hundreds of dollars SHOULD perform very well and last - and preferably be backed up by warranty.

- Tunability. This ties into the "I don't want to be an electrical engineer just to tune my car" discussion, but what about a year from now when someone wants to switch to larger injectors, gets a smokin' deal on a new turbo or whatever? How much tunability can one expect without having to spend hours sitting in front of a computer screen? I do that all day at work and like to work on my cars because it's DIFFERENT than that! What's the deal with getting new chips burned to compensate for after-the-MAF upgrades?



Thanks for the good, civil and informative debate and information here. This is good stuff.

promax_motorsport

Hi Jeff,

If you change the config of your car, we can quickly re-map a DME chip for you (if required) and send it over. The standard DME chip (for those that order with the MAF) has settings for standard and 55# injectors and fuel maps for 3 different boost levels (1.0, 1.2, 1.2 for larger turbo - flat boost to redline). All selectable via the FQS and RCP/IA plugs.

On the car we did yesterday, it has exactly the same MAF set-up as a standard car would have. It just runs a different DME chip and Manual Boost Control.

Remember, we have now agreed a Rennlist only group buy price of $849.95 including shipping and 30 day money back satisfaction warranty.

Have you seen the install instructions yet?

Regards,
Andrew

Porsche-O-Phile

Thanks, good to know. Yea I saw the install pics - very straightforward. I suspect that'd take about 45 minutes tops accounting for liberal beer consumption.

Just wondering also what the exact advantage of a standalone MAF versus a "signal massaged" MAF (like Ted mentioned) is. Pros/cons?

fast951

Andrew, Why would you even care what boost level the car is running? The air flow is the important factor! The air flow will be different at the same boost level between 2 different turbos, even same turbo with a different flowing head .. To make things even more complex, the boost characteristics of the turbo (not just the flow) correlate directly to flow at a certain RPM.. So how would a chip rated at 1, 1.2 or 1.x bar handle this??

If the MAF conversion is done correctly (using a transfer function in the chip/software), the proper MAF will measure the correct flow, then the DME will know the correct LOAD which is used to calculate fuel & ignition..

Anything other than a proper software requires additional MAF signal modifications, be it by redoing the AFM chip or changing the converter box you use...

The above does not only apply to what Andrew is offering, but to ALL MAF conversions on the market that rely on a MAF signal converter for the DME to work...

Since many people on this board are interested in a MAF conversion, you might want to investigate deeper into what you are getting. For some reason, the price is about the only variable people tend to see!
Do it correctly the first time, or spend your money the first time, then spend more money to get it done correctly the second time!!!

Andrew, not hammering you here, just pointing out the facts!

schnellfahrer

By "accident" I boosted to 28psi with John's MAF kit.
The AFR stayed exactly the same as when I run the car at 15psi.
Not bad, ey?

fast951

Does "accident" mean: I don't want John to send me a nasty email?

RK951

I think its hard for those outside of California to understand how important this issue really is.

schnellfahrer

marcoturbo

I currently run a SciVision MAF on my '86 951. With my set up (Guru/Promax chips, 3 bar FPR, Accuboost set to 15 psi), it's a great improvement on stock AFM in drivability. I also noticed low rpm torque has raised.

The main reason I switched to this AFM is, like Porsche-O-Phile pointed out, stealth. I don't want people notice my car has been modded when I open the hood Scivision MAF is also a bolt-on unit very easy to install.

I wish Vitesse hadn't offered a stealth MAF when I bought mine... But I'd very interested in compare my Scivision MAF to a stealth VR one

turbinek

originally from Germany ask info@scivision.ag

see "maybe the perfect working maf"

turbinek

[QUOTE=fast951]The air flow will be different at the same boost level between 2 different turbos, even same turbo with a different flowing head .. QUOTE]

Dear John - I have to apologize - you share some info. Put's your products in even better light! I guess it may be the best U.S. Product.
kind regards Frank

Transaxle

That is true. You have to know the current mass flow from the MAF - that is easy. You have to know the current density of the air - that is easy too. You can then calculate the volume flow. This value has to be set to the correct output voltage based on the DME reference voltage. That is not so easy, since the calibration of the AFM has to be known.

You can try to set the AFM and the MAF in a row to get comparable - but experimental - values. The problem is the pulsation of the air flow that makes it difficult - if not impossible - to get the correct transfer curve. You have to build a powerful and static flow bench to do that job.

Even with that we had a lot of problems to get the right transfer curve until we got the original calibration sheets for the AFM from the Bosch archives. And they calibrate their AFM 5 digits behind the comma!

But even then you have to take care for the WOT mode. The AFM reaches its physical limits around 5000 rpm. The DME then flys blind. A correct DME software must be based on the boost curve programmed in the KLR or by any other boost control system. If the max boost increases by using the MAF technologie, you have to adjust the fuel injection.

Not to mention the software to smoothen the MAF signal in real time or to simulate the over swing effect of the AFM flap....

fast951

Transaxle, good post. However when you convert the MAF signal to look like an AFM signal to use the AFM transfer function in the software, you are limited to the flow of the AFM...
There are many issues involved, you hinted on a few, but there is lots lof issue to sort out..
How many people here using a signal massager are having to mess with the mixture when the outside temperature changes?

Again, the ONLY proper way is to have a transfer function for the particular MAF in the chip itself. No massaging, correct calculation etc... Get a the proper MAF, set and forget.

Good/Correct signal data IN = DME calculates good data out (Fuel and Ignition)

TT

You only have to do the mass/density conversions if you use an external massager between the MAF and DME. If you change the DME code so that the internal calculations deal with air mass instead of volume, none of that is required. I examined how Bosch integrated MAFs into the DME code for the later model cars and applied this to the 951 DME. The modified DME code in the Vitesse MAF kit does not have any of the limits of the stock AFM or DME. As long as you get injectors and a MAF large enough to cover your target HP range, it will provide enough fuel to maintain the proper AFR regardless of boost level. The stock DME code already had provisions for tip-in and air meter response so that only required some tweeking to get correct. The DME code for the Vitesse Kit also has semi-batch injector support (allows use of 72lb+ injectors without modifying the fuel maps).

The MAF from the Vitesse kit was selected to cover the HP airflow requirements for just about anything someone could coax out of the 2.5-3.0L engines. Special Tool isn't close to reaching the limits of the MAF he is using. I looked into using the Bosch HFM5 units a few years back, but the air flow sizing, price, and reliability issues pointed me towards Hitachi.

On my 944NA daily driver test mule, I am currently running the Vitesse 951 MAF along with 75lb injectors using the stock fuel and ignition maps with no piggyback. Overkill for an NA, but it runs no differently than if setup with a smaller MAF and injectors.

Skip: If you do go with the Vitesse Kit, I would suggest selling the 55lb injectors and getting a set of 72 or 75lb injectors. That way if you decide to go with a larger turbo later, you won't have to call John again.