951 S w/ Chip Spark Plug Question

[944sracer]

Hello All,

I know that this horse has been beat to death but here we go again.

Stats:
89 951 S - Race Track ONLY Racecar
- Autothority DME and KLR advertised 50+ HP/TQ
- aftermarket test pipe + 3" exhaust
- All other Engine components are stock

I am looking for a spark plug choice. I know that there are a ton of options out there but what do you guys run or suggest? and the all important follow-up question - WHY?

TIA

[Techno Duck]

I would do one step colder, i prefer NGK BPR7ES. The colder plug will help prevent detonation, especially considering this is a track car that will see prolonged boost.

Do you have a wideband on the car? The autothroity chips in my experience run very lean above 5k rpm.

[944sracer]

Good information, thank you.

No, I do not have a wide band O2 Sensor. Just the factory. Can you tell me more about the wideband O2 sensor?

[Techno Duck]

It is a standalone gauge / sensor put in the exhaust. Much more accurate than the factory narrowband O2 sensor. Not a bad idea to have it, especially on a modified turbo.

[944sracer]

Ahh I see. But the wide and will not be able to be feed into the older technology chip so the car can adjust right? So I would have to add a higher pressure fuel regulator to increase the fuel the the injectors squirt? Correct?

Also, what have you heard about weltmeister chips? Any chip you would recommend?

I am running with NASA PT series so my suspension mods bump me 2 classes but on a stock motor I'm grossly underpowered. I am hoping to get a little bump in power combined with a drop in weight to make the car a little more competitive.

However, motor longevity is most important. So if I can run say 2-4 more lbs of boost I can get the HP I need yet still have reliability and longevity?

Thoughts?

[Techno Duck]

The wideband gauge and sensor does not interface at all with the factory Motronic. It is just there for your use to observe the air / fuel ratio.

Increasing FPR will help, but is not a good way to go about tuning as it makes adjustments over the entire spectrum as opposed to addressing the actual problem. In short, it may cause other problems while trying too fix the main issue.

I have no experience with Weltmeister chips. I do have experience with the Autothority Stage 2 though. When i ran them i saw very rich in the mid range, and fairly lean uptop. If i remember right it was down to around 10.5 AFR in the mid and leaned out to around 12.5 or so at higher RPM. For best spool, you want to be around 12.5-12.8 AFR in the mid range (as boost builds), and by full boost you want to be around 11.4-11.8 AFR to play it safe.

Assuming you are still using the stock 26/6 turbo, a good chip and upping the boost to about 15psi will get you around 260whp.

As for which chip i recommend, if you are staying with the AFM based setup i highly recommend checking out Vitesse. In my opinion he has the best product available for AFM based setups and his level of tech support is about as good as it gets.

I think these cars with an extra 3-4psi (15psi) do not loose much reliability. One you go over that though is when things start to go south. My car is pretty heavily modded, if i could do it over again i would have just done the MAF conversion, 3" exhaust and left everything else alone. Once i put on the bigger turbo and all the other stuff is when the problems started happening.

[944sracer]

Ok, good to know. Thanks

I am an S so I have the #8 hot housing.

Also what do you know about lindsey's chips? Or Powerchip?

I really want to keep reliability as I am on a budget for racing as it is.

I will look into The chip you recommended.

[nize]

have you checked the 951 reference list here? it covers the details regarding spark plugs and such;
Porsche 951 (944 turbo) reference list