Custom DME chips

[Alex89]

Hi all, this is my first post here on the new forum, great to be here. I've been gathering information on the old-school method of tuning our cars: burning custom chips for the stock DME. I'm well aware of the newer standalone systems and I will likely play with them in the future, but for now I'm interested in exploring what the original systems could do with some "period correct" mods. It also helps that a chip burner and spare chips can be bought for around $60.

I've found and read the DIY tuning page on the Rogue tuning website. I was successful playing around in TunerPro with small tuning changes to my stock 951. I'm now upgrading my turbocharger and injectors and will need to create a new tune for my car this spring.

I'm looking for advice on where to start when making a new tune, and what the process should be. If anyone can share their experiences with this, and/or share any bin files they have of their own tunes I would greatly appreciate it. Thanks!

[Tom]

Hi Alex and welcome to Carpokes. For my 951, I've relied on Vitesse tuning for the last decade or two, so have never tried to modify the factory DME maps. I've burned chips using factory or modified BINs, but never tried to edit the BINs. There are those here with gobs of experience though, and I'm hoping they come out of hiding to chip in on this. (I may quietly ping a few) Either way, very much hope you keep us posted on your progress!

[DannoXYZ]

One good exercise is to export maps of Turbo vs TurboS maps to Excel files. Then plot 3D charts to compare. Much easier to visualise than looking at columns of endless numbers.

You can also use Excel to calculate differences between the two maps and plot that difference as 3D chart. This REALLY helps illustrate difference between those maps.

Then you can extrapolate those differences to make maps for bigger turbo and more boost. Usually remove fuel from low-end due to less flow and more lag. Add more fuel higher up for more air-mass from more boost. Fine-tune with wideband.

[Alex89]

Thank you both for the welcome.
Tom I appreciate what you're doing with the forum and helping to grow technical knowledge for our cars, especially with the written how-to guides. If I'm successful tuning my engine I plan to also document the process and hopefully help others considering this option.

One good exercise is to export maps of Turbo vs TurboS maps to Excel files
...
Then you can extrapolate those differences to make maps for bigger turbo and more boost. Usually remove fuel from low-end due to less flow and more lag. Add more fuel higher up for more air-mass from more boost. Fine-tune with wideband.

DannoXYZ this is exactly the type of suggestion I have been looking for. My other big question is if there a source you can share for the TurboS (K26/8) map? Or any other maps for that matter. The one resource I've found to date is Rogue Tuning where I downloaded the stock NA and 951 (K26/6) maps. He also gives a good introduction on TunerPro but not very much detail on the actual process of making new maps.
http://www.roguetuning.com/diy_free_944_tuning_tools

I've been unsuccessful finding any tuning maps for a larger turbo so far. I can try sending you a private message with my email address if you have anything to share. Ultimately I think it would be cool to make my own maps and share them openly and make this easier for people in the future.

Thanks again!

[Tom]

Just FYI, back before iPhones and Facebook, Danno was a popular chip tuner for the 951. I ran several versions of his chips in my car, as did a lot of the greying 951 owners on this board.

You might want to start just getting some EPROMs and burning a stock chip to make sure you have the basic building blocks in place. It's all kind of vintage stuff these days, so kind of like tracking down typewriter repair parts/info. Porsche switched from a 24 to a 28-pin EPROM along the way, and you need to deal with the overboost protection, etc. Most performance chips back in the day came with a modified KLR chip for that reason. Also know that if you are sticking with the factory AFM, it maxes out well below the power levels you can achieve with aftermarket turbos....

If you start making progress and still can't find an S-chip BIN, let me know.

If you are a tinkerer/hacker at heart, I'm sure this will be a fun and rewarding project (and one I'd love to watch unfold here on carpokes). If you are just looking for a great tune for your car, I'm sure it will be quicker and cheaper in the long run to just contact Vitesse Racing.

[Alex89]

Hi Tom, I'm not familiar with Danno so thanks for the introduction. Nice to know there are people with solid experience who are willing to help. I'm actually a bit farther into this than I've previously explained.

Last year I bought a Vitesse DME chip for my stock 1986 951 with the K26/6 turbo. John informed me that a modified KLR chip isn't needed if I bypass the cycling valve and use a manual boost controller to increase boost. My DME already had a 28 pin socket.

Long story short, I was happy with the Vitesse chip but I discovered some worn parts on my car that were keeping my boost below 11 psi. This winter I'm replacing some of these major components, including a bigger turbo which I'm told is similar to a LR S48, Deka 80lb injectors, a 44mm wastegate, and a 3" exhaust.

With these new parts I need a new tune. I was happy with Vitesse's service but wasn't aware at the time that it is even possible to make your own chips. As a tinkerer and general electronics enthusist I'm very interested to learn what goes into making a tune and excited to experiment with my car.

I've aquired an XGecu TL866II plus universal programer and some blank SST 27SF512 chips. AliExpress is wonderful for these things. So far I have burned a few chips, played around with some tuning values, and I drove about half the summer on my own chip. I'm comfortable with everything up to this point.

The next step will be to create a new tune for my go-fast parts. I'm hoping that by the time my car is running with the new turbo I'll be ready to go with a rough tune.

Here's a little preview of my new turbo. I'm very excited to see how it will do. One of my issues was that the stock exhaust had collapsed internally so I'm sure the engine being able to breath will make a big improvement on its own.

[Tom]

Ah, well that's much different. It's always hard to know where people are on the 'journey' with these cars. John could program a lawn mower to go faster, so could help if needed, but I totally get the hacker's challenge element. Looking forward to hearing how you get along with the project. Are you planning to use the stock AFM with that turbo. It 'looks' like it outflow a stock AFM...

[Alex89]

Tom to be honest I had not considered the AFM. For reference my turbo was made by TEC (Turbo Engineering Corp) and is a T04E 50 trim with 0.60 A/R and #8 hotside (I can't pretend to understand what any of that means). It is a direct fit to the 951 and I'm told it is very similar to a Lindsey Racing Super 48; probably good for around 325 HP. From some quick googling that seems to be the upper limit of the stock AFM so hopefully I'll be alright.

Direct message incoming regarding the K26/8 tune. Thanks.

[Fast951]

Alex,

I think you'll be ahead if you get a good idea on "tuning" in general. Once you have the theory well understood, you can move forward.

Comparing chips will show you "what" has been done but not "why". To properly tune, you must understand the goals and the why...

Your turbo supports much more HP than the AFM supports. However, if you keep low boost, you'll be fine.

The injectors you chose are good, however it's going to be a challenge to tune properly.

Take it one step at a time. Don't rush things, mistakes can cost big $.

[Tom]

In the spirit of John's post, I found this book pretty darn good on the theory of tuning. Some books are totally shade tree and some are totally engineering formulas, but I thought this one does a nice job of combining science and art. John may think it's hokum though, I dunno.

tuning book.jpg (44.58 KiB) Viewed 1751 times

Personally, I'm not sure I'd install a big turbo if I planned to keep the boost under the AFM limit forever. You may end up with with less power under the curve if it's laggy on the bottom end, and turned down on the top end. No idea about that particular turbo though, but it 'looks' big. A K26/8 with a nice tune and boost controller may be the AFM sweet spot, or one of John's cheaters. Don't get me wrong, I'd install a big turbo, I'd just start considering additional supporting mods to take full advantage of it.