V2Rocket

the 2.7/3.0 blocks have the different water passage.

the 2.5 NA/S/turbo blocks are identical.

pettybird

It's cost. It's always cost.

m73m95

Who says you can't use modern MAF and MAP sensors with the DME already in our cars? And who says you don't have total control over Fuel and Timing on the stock DME? I'm already using a MAP sensor, and will be running a true MAF (Not a piggy back) in a few weeks.

Contact Rogue_Ant for all the information you need.

In many ways, the stock DME is better than a stand alone. Why try to write and tune hundreds of maps, when all you really want to adjust are the maps you drive with (idle, and part/wide open throttle)?


And, pertaining to this post.... I'm sure you could run a 16v turbo setup with the stock 951 DME/KLR, but why? It would run, but you wouldn't get the full potential out of it. You've spent thousands of dollars building the engine, and making parts....and you're not going to tune it? You can tune your engine for $175...right now if you like.

Ostrich

Or, you can have a MAP and MAF setup for you car, 8v or 16v, very soon. Rogue_Ant will burn you chips for whatever setup you want. Not only 8v or 16v, but how about E-85? How about flat foot shifting (2 step rev limiter)? How about a switch that will let you change tunes? Gas for Daily Driving duty, and then E-85 for turning up the boost on track days?

86 951 Driver

Doesn't Vitesse already do this? Not trying to knock anyone, but it sounds similar except the switch part.

I am not an expert in any of this engine management only in 2 stroke motors.

Jfrahm

It would be interesting to know what Porsche would have done if they wanted to keep making the 951 or a 968 turbo. Saab and Audi went to 4v heads in the 80's on turbo cars with great effect.

Porsche did not need the 4v to meet the performance goals of the project and ultimately did not even need turbocharging. Sad really.

Yes in the 951 you can cram in all the air you need through one intake valve per cylinder to hit 300fwhp but better flow is more efficient. Audi made 951 HP numbers with a 2.2L motor and a K24 turbo. A 2.5 16v with a K26/8 would probably hit 280fwhp easily with factory exhaust and boost levels.

For a street car I do not know why one would bother with a 16v head swap when there are other ways to spend your money, unless there is some reason you want a particular flavor of HP.

My ideal (realistic) 951 motor for street is probably something like a 3.0 16v motor at 9:1 CR and 300-ish rwhp through a cheater K26/8 (or similar) and a quiet exhaust but that is not a typical build.

-Joel.

m73m95

To my knowledge, Vitesse converts the MAF signal into an AFM signal that the DME can read. Rogue_Ant rewrites the code in the DME to read the true MAF signal.

I would contact Rogue_Ant to find out for sure.

And besides, Vitesse's stuff is astronomically expensive. I know Rogue's kit will be significantly less expensive.

ZR8ED

Sure you can change upgrade your sensors with your DME. Anything can be made to work. As the modifications become more advanced it becomes another story altogether.
There is also nothing wrong with modifying the stock ecu if you have the equipment to burn chips. It is more likely though that someone has a laptop available to them and a usb cable to plug into the ecu. You can easily datalog and use that info for fine tuning/troubleshooting. A shop that does a burn for you can only burn based on what you tell them about your car, or have them put it on a dyno. Any other type of "chip" will be full of compromises as they must be able to be used by a wide range of users. As an added bonus, it costs you nothing to continually adjust for every additional mod you ever make afterwards by simply by saving your last known working ecu file. No risk to wrecking a good file. keep it saved on your harddrive and work on it anytime you like. Larger injectors, methanol injection, Additional injectors, boost control, wastegate settings for multiple boost stages as well as adjusting for your driving style (cruise, drag, roadcourse etc), climate changes (elavation, winter, coolant temp/fan controls etc) Aftermarket ecu controllers are far more available than ever before. Some are very easy to setup and use, others require more technical knowledge, but there is nothing like being able to go to the track and keep on tuning to your hearts content. Many have easy to read graphs and indicators, You can watch and tune settings live and there is no need for multiple tune files unless you are going to run different fuels or engine components on track days.

I've modified stock systems in the past, but now that I have gone on to more modern aftermarket engine management systems, and am much more comfortable working with computers, I have found it to be much easier, faster, and cheaper in the long run, because who ever stops modifying? Boost is addictive...Well that and old school Weber sidedraft carbs (but that is another story)

m73m95

Please contact Rogue_Ant. He can fill you in on everything you ever wanted to know about the DME.

I've provided a link to an emulator that will allow you to tune your DME how ever you like. Here is Rogue_Ants thread with instructions:

Tuner Pro Walk Through

If you want to add modern Injectors, MAF, MAP...whatever, then you'll have to contact Rogue. My knowledge is FAR less than his about the DME. He is also gearing up to release an entire kit for the MAF/MAP/Custom chip setup

fast951

I'm not sure where you get your information from, but you are misinformed.
Our software is Genuine MAF, we rewrote the software on the chip. We do not convert the MAF signal to a AFM signal so the DME can read it. The Vitesse MAF software understands MAF. We support many MAF sensors and various calibrations, as each MAF requires a unique transfer function in the software. To add to it, with the introduction of the Vitesse V-FLEX software, we incorporated a MAP sensor the alter ignition based on actual boost. We also introduced support to E-85.

If you like more details, take a look Here.

m73m95

Ahh ok... I was mistaken. I do not know a whole lot about your setup. I know there are "piggyback" setups out there that use a MAF sensor, but don't use the true MAF signal.

I do know that Rogue_Ants system will read the true MAF signal, as well as the MAP signal. I don't want to overstep my bounds talking about Rogue's system, so I will let him give more details, when he chooses too. I know he has things in store for the 944/951 community, and he should be posting about it very soon.

67King

Velocity is actually more important at higher RPM, as the ram affect becomes critical to filling the cylinder. Runner length and cam events are a LOT more important than velocity at lower RPM. But in this situation, we aren't talking about the kind of difference you use as an example. Two 37mm valves has a single valve equivalent of a 52mm.

What is funny is that different OEM's have different phlosophies for velocity. The higher velocities are on the order of 100m/s, and the slower ones are 80m/s.

My *peronsal* opinion on this is to use the smallest valves you can to meet your goals, for two reasons. First, within a given envelope, smaller valves allow you to have a larger short side radius, which is better for flow. Second, for the reasons you mention - increasing velocities.

FWIW, if you overlay the last SN95 Mustang 2V (GT) and 4V (Mach1) torque curves over each other, the 4V makes more torque across the board. That is just an example I'm familiar with. I haven't looked at the 944 NA versus S. I think the 5.4L were the same way (Lincoln Navigator had a 4V, but the Expeditions and F-150's had 2V's)>

m73m95

I just threw out a number to convey my point .... 80mm valves are ridiculous.

I will have to disagree with you about velocity being less important at lower rpm.....

pettybird

You can't compare the ford 2v to the 4v like that--there's cam timing, compression, intake runner length and more to take into account.

How about Hondas or other Japanese cars? They switch from SOHC to DOHC all the time, as does Mitsu. There has to be a closer comparo there.

m73m95

http://www.clarks-garage.com/tech.htm

You can see that there is a 30hp and 30ftlbs difference between the 944 NA (87-88) vs the 944S (87-88)....the main difference being the head. Both are 2.5L engines.

running_cold924

i remember my S, it loved to be above 5500rpm all the time. loved to be revved. that was where the power was, for sure. it also had a higher compression but then again, the 88s did as well before they went 2.7.