Hello,

In an other thread I hinted at something we have been working on here.

I have heard a lot of back and forth in terms of E85 and its safety and such in the Porsche. We have used it for years in a slew of other cars with great success. I always suggest that you measure the content of the E85 to be sure that it is indeed what you are tuned for, but for the most part E85 is pretty solid fuel.

What I can say first off is that the best thing you can do for power in the 997.1 Turbo is to run good fuel. These cars honestly HATE 91 octane of any kind, and a lot of power can be made just by running a good fuel in the car. Just by doing this you will have the ability to make much more solid, reliable power. Probably the best thing you can do for these cars is to spend the money on a good fuel. I would say most customers of ours don't daily the cars, and so being able to run race gas is a little more feasible in terms of cost and inconvenience.

Now I do totally understand that E85 is not available everywhere and neither is race gas, so I 100% understand that situation and that is why we try and make OTS maps for every fuel so that customers have options.

We wanted to first measure and see how strong the stock fuel system was in terms of power. I know some guys run stock injectors on E85, I do not advise customers to do this as the car has to be turned down in order to do it safely. I always recommend that customers spend the money and put injectors in the car and size them appropriately. A good solid 1000cc injector is perfect for a stock turbo/ modified VTG car honestly. I would say go to a 1300 if you ever thing you are going to go to something bigger than a VTG that way it will maybe save you some money on injectors. We always recommend Injector Dynamics injectors as their data is second to none and the quality is the best I have seen to date. My car was the test subject and was fitted with Cobb 1000cc Injectors. We get these from Injector Dynamics and in doing so request a slightly tighter tolerance in terms of deviation of flow. *Shameless plug, you can buy them from us!*

We fitted the car with fuel pressure sensors, IAT sensors, and EMAP. For those that are unsure of what EMAP is it is Exhaust Manifold Pressure. I have found EMAP to be a very crucial tool for measuring engine performance. It is a great way for us to see how well the volumetric efficiency of a motor is working. Measuring air in versus air out is a great tool as it helps to tell a story of how the motor is working. Most times intake manifold back pressure is used and that is only a small part of engine efficiency. I use this when tuning Pikes Peak hill climb cars and have gathered a lot of data through the years on elevation changes on different turbos, and then can use that to help me to plot efficiency of various things (when measuring a few other variables).

Anyways, here is the data of the boost pressure versus fuel pressure:












The first graph shows the correlation between intake manifold pressure to fuel pressure. As you can see the stock pumps do a great job keeping up with demand. Really no need for a larger fuel pressure regulator unless you are right on the edge of maxing out the fuel system. On a good set of 1000cc injectors and stock fuel pumps you should have plenty of fuel for E85! Porsche really did a good job on the 997.1 Turbo fuel system. Highest injector duty cycle we saw was 76%, which leaves a decent amount of head room for if you wanted to go a bit higher.

Next up is EMAP versus Intake manifold pressure (Boost):





This is where things really get interesting as you can see just how much back pressure the stock turbo's will running 20psi of boost. On pump fuel this is a big part of what causes detonation as the air gets so hot the turbo moves way past its "adiabatic" efficiency, and just starts to heat the air. Now during this I also added AMS Intercoolers which made a huge difference. This has been measured and tested by AMS so no need to do it again, but they are really amazing intercoolers.

So at 20psi of intake manifold pressure at redline on the stock turbos you can see we are hitting almost 50psi of back pressure. Needless to say that is a lot!

Here you can see where we mounted the EMAP sensor:




So what this shows us is that just because you are running a large amount of boost it does not mean that it is really doing a whole lot in terms of performance, and in some cases, is actually hurting performance. More boost is not always better.

So after a lot of testing, Jon and I came up with a great set of OTS maps for E85 for the 997.1 Turbo. These maps will hopefully be available in a couple of weeks and are free to any of our current AP users.

You will need to run our 1000cc Injectors in order for them to work and I would suggest intercoolers. ( I would suggest intercoolers for bone stock cars honestly haha) Aftermarket exhaust is also needed for this, as the back pressure would only be worse on a stock exhaust.

Put it all togeter after lots of hours of testing and you come up with the final result!








Please feel free to ask questions, I figure this is just good info for the community. I will measure this more on other cars as they come in. I want to get this in our 997.2 Turbo to see how similar it is on the 9A1 engine. I want to see this info on modified VTG's as well so maybe when the next one comes in I will pop in the sensor to take a measurement.

We have some more data we will add to this in the next couple of days, so keep an eye out for it!

Thanks for looking!

Mitch Mckee
Jon Hebbeln
Cobb Tuning

 

Awesome data. Really appreciate you guys sharing it out as many vendors in the past have either never done anything like this and/or never shared detailed results with the community.

50psi of backpressure is 2.5:1 to intake which isn't great but if you close down valve overlap up there its not that bad at all.

What exhaust was on this car by the way?

Dzenno@PTF

 

GMG with cats and we can plot cam timing if you want. It's still a lot of back pressure haha, but you are correct.

Mitch

 

Mitch, stupid question..

can I get the 1000cc injectors, and run E85 when I want and switch back to 93 for normal driving?




Neil

 

Not dumb at all! When we release the maps we will also release Stage 3 pump gas maps. That is a must for us. So you would just need to flash your pump gas map on after fill up.

Mitch

 

Stage 3 pump gas! I may have to order these injectors, I think I'll hit that 1/4 mile number we were trying for last season.

 

This is really good data Mitch and good power results for stock turbos. Backpressure on these def has a lot to do with cam overlap and you will continue to see it even with bigger turbos. where did you put the sensor for fuel pressure?

 

We put it on the fuel filter. I will snap a pic when I get into the office and post it up. Pretty straight forward little spot at least for testing on the dyno.

-Mitch

 

yeah we used the bleeder valve port and it worked ok. pics would be cool and also what sensor did you use to work with the mustang dyno for fuel pressure. i'll ask garth pick one up too.

 

Ours is off the bleeder as well. Works pretty well.

We use a 10 Bar Kavlico Pressure Transducer. If Garth wants to shoot me an email I can show him how we have it hooked up to the dyno. EDIT- Any 0-5 volt pressure transducer will work, so if you guys have an AEM one or something we can get it setup as well.

We pulled the fuel pressure sensor off, but I can get it back on and take a pic if you want to see it still.


Thanks,

-Mitch

 

Awesome Mitch!

 

I thought AEM was just relabeling the Kavlico sensors but that was years ago so maybe things have changed.

A picture would be nice, if you could share what adapter you are using to go from the inspection port/bleeder to the sensor that would be useful too. Any chance we can hook these up to unused inputs on the ECU and you can let us log them with the AP?

 

Mitch -

You mentioned looking for a VTG car to measure up on. Shoot me a PM, we've already talked about you meandering to Plano so would be happy to also help you gather the data you need.

 

Haha no way, I will get him from the airport and hide him from you!

 

Looks like I will be in that area for TI.

Might be a good time to meet up with you guys!

Let me know and I can get it planned out.

Mitch