First E85 tuned GTR - Cobb AccessTUNER PRO Options

[COBB Tuning]

E85 is a blend of 85% ethanol and 15% gasoline. Originally developed as a bio-fuel for "flex fuel" domestic cars in the US, E85 has become the alternative fuel of choice for performance enthusiast. The allure of this biofuel comes from its high octane compared to regular pump fuels - 91 to 94 compared to 105 - and a very low price compared to higher octane race fuels. In many parts of the USA E85 costs as little as 2 dollars per gallon. When compared to 8 to 14 dollars quality high octane race fuels E85 represents a huge bargain.

If you don't know about E85 you're naturally asking the question "why am i not running e85 every day?". The answer is you can't. Most stock vehicles are not calibrated or equipped to utilize ethanol based fuels.

Despite having a higher octane rating, E85 has a lower overall energy density than pure pump fuel. Pure gasoline contains approximately 125,000 BTUs per gallon, while E85 contains approximately 84,000. This means that a greater volume of E85 must be utilized to realize the same energy content. This lower hydrocarbon content is mirrored by the stoichiometry of E85 and pure unleaded gasoline. Complete combustion of pure gasoline requires 14.7 parts air (mixed gas air with 23 percent oxygen) with one part fuel. In contrast, complete combustion of E85 requires a much higher relative content of fuel with only 9.7 parts air required. The distillation of this information means that larger volumes of E85 are required for equivalent combustion when compared to pure pump fuel. Thus, the cost savings associated with lower E85 prices is offset by an overall reduction in fuel economy. (taken from driving sports article "methanol injection vs E85" i wrote the article so i'm plagiarizing my own work. http://www.drivingsports.com/site/2008/07/...anol-injection/


The graph below shows the stochiometry of E85 (lamda) is similar for pump and E85 but the volume of fuel required for E85 is much higher by proportion (Air to fuel ratio).



Despite these limitation of E85 we wanted to tune our GTR to utilize this fuel. Together, the lower cost, higher octane, and higher overall power potential are simply too much to resist. Furthermore, because E85 has not been used in the new GTR platform I simply couldn't resist the technical challenge.

Because a stock GTR can use nearly 100% of its available injector capacity on pump fuel the first step in using E85 is to replace the stock injectors with larger units. We chose to use Deatschwerks 800cc injectors. These are ~30% larger than stock and should be able to provide the additional fuel volume needed for E85.

The injectors were installed and the car tuned on pump fuel:

Stock - completely stock calibration with 92 octane pump fuel - BLUE

Stage 2 800 cc - COBB catless midpipe, COBB prototype cat back exhaust, stock intake, stock fuel pump. - RED



We then drained the tank and refilled with E85 full. I adjusted the calibration with COBB AccessTUNER Pro software and prepared to run the car. The first few runs were done at low boost and all was well.

The calibration was then adjusted for higher boost and we attempted a full run. I aborted the run because the motor went progressively leaner at RPMs and fuel demand increased.


This increasing lean condition clearly points out a lack of fuel delivery. Because our injectors are mathematically ideal for ~30% higher flow it's clear that the stock fuel pumps simply cannot keep up with higher duty cycle with 800cc injectors.

To combat the lack of fuel we installed two walbro 255s in the place of the stock fuel pumps. The installation took about 4 hours total as the stock in tank fuel surge tank needed heavy but straightforward modification.

With new fuel pumps installed we went back to the dyno with high hopes of sufficient fuel delivery. The results are presented in the graph below.


Stock 2009 GTR - 92 octane - BLUE

Stage 2 800 cc - COBB catless midpipe, COBB prototype cat back exhaust, stock intake, stock fuel pump, 800 cc Deatschwerks injectors - RED

Stage 2 800 cc - E85 - COBB catless midpipe, COBB prototype cat back exhaust, stock intake, Twin walbro 255 fuel pumps, 800 cc Deatschwerks injectors - GREEN

This E85 Stage 2 configuration is now the highest HP and torque stock turbo car tuned on our Mustang dyno. When the weather clears here in the pacific northwest we'll find some dry test roads and report V-box data. We're also planning to rent a local drag strip for development and testing so ETs and trap speeds are coming.

As a next step we plan to install some custom intakes. If our early observations are correct this car will make more than 600 whp on stock turbo's with E85.... all while retaining the factory downpipes.

Best regards
Tim Bailey
Lead GTR calibrator
Cobb Tuning SurgeLine
Lead GTR calibrator

This post has been edited by COBB Tuning: Jan 18 2010, 12:34 PM

[COBB Tuning]

Place holder for data logs and more technical goodies

Here's a comparison of Injector Duty cycle with Pump fuel and E85. Clearly E85 requires a lot more volume. This is the data for the dyno plots in the above post.



Regards
Tim

This post has been edited by COBB Tuning: Jan 18 2010, 12:33 PM

[davidm_sh]

That is some really nice gains and I have been wondering and waiting for someone to try out E85. One question I had though and am curious if you have any insight into it. I thought it was VERY odd that there were about 4-5 pages in the owners manual about not using E85. For obvious reasons as you state above it does require tuning to make it work and if the car is only tuned from the factory for gasoline the car would not run well if at all if you put E85 in.

But the lengths at which the owners manual goes to warn against using E85 really made me wonder if there was some component in the engine or fuel system that might disagree with it to a detremental extreme? I mean they have tolerate 10-15% ethanol for gasoline since that is a common blend in parts of the coutry, but it just struck me as odd is all that they talked so much about it in the owners manual.

I know and have first hand and second hand experience with using it in Subarus for 3-4 years now and it works great so I am sold on the stuff just a bit apprehensive about trying it out in the GTR yet.

[Sean@Iveytune]

Very nice Mr. Bailey.


Sean

[gotboost]

As a next step we plan to install some custom intakes. If our early observations are correct this car will make more than 600 whp on stock turbo's with E85.... all while retaining the factory downpipes.

Tim, this is getting fun!!!
Wait to people see how much your car makes with my new custom intakes installed! (Kudos to Tim with some insight on the design parameters.)

Much more info on these to come soon!!

[HB Speed]

Tim, this is getting fun!!!
Wait to people see how much your car makes with my new custom intakes installed! (Kudos to Tim with some insight on the design parameters.)

Much more info on these to come soon!!

kinda like this?

[celsius]

THIS IS AWESOME!!



GotBoost / Tim.....when can I get those goodies!

[MindlessOath]

That is some really nice gains and I have been wondering and waiting for someone to try out E85. One question I had though and am curious if you have any insight into it. I thought it was VERY odd that there were about 4-5 pages in the owners manual about not using E85. For obvious reasons as you state above it does require tuning to make it work and if the car is only tuned from the factory for gasoline the car would not run well if at all if you put E85 in.

But the lengths at which the owners manual goes to warn against using E85 really made me wonder if there was some component in the engine or fuel system that might disagree with it to a detremental extreme? I mean they have tolerate 10-15% ethanol for gasoline since that is a common blend in parts of the coutry, but it just struck me as odd is all that they talked so much about it in the owners manual.

I know and have first hand and second hand experience with using it in Subarus for 3-4 years now and it works great so I am sold on the stuff just a bit apprehensive about trying it out in the GTR yet.

i question that as well. does e85 clog anything up?

also wanted to ask what would a stock system with a dual fuel pump upgrade do? i ask because your using both E85 and the dual pump but no dual pump on the stock gas. how much of those gains are from the gas, and how much from the pumps. obviously well see more gains from the gas because of the higher oct rating.

will be neat to see 600+hp without blowing all that hot air and potentialy damaging something.

[dukestar]

It appears that you ran the 800cc injectors with stock pump on 92 octane pump gas and did not go lean. Is that correct? Is is true that if we don't choose to run E85 there is no need to upgrade the fuel pumps when going to 800cc injectors?

This post has been edited by dukestar: Jan 16 2010, 11:51 PM

[COBB Tuning]

It appears that you ran the 800cc injectors with stock pump on 92 octane pump gas and did not go lean. Is that correct? Is is true that if we don't choose to run E85 there is no need to upgrade the fuel pumps when going to 800cc injectors?

If you use stock intakes the stock fuel pumps appear to offer enough fuel flow for non-ethanol based fuels no matter what kind of injector used.

However, after tuning gotboost's car with and without intakes just tonight it is VERY clear that stock turbo's optimized with intake and exhaust modifications can overflow the stock fuel pumps. Look for another tech post very soon. I'll report the details as soon as i collect the data and get some graphs together. The take home message is that stock intakes are a critical limit to airflow and power. I'm quite frankly surprised at how much we gained with intakes and nothing more.

As soon as Gotboost fabricates a second set of intakes i predict my E85 powered R-35 will make over 600 whp. The current tune was accomplished with stock intakes. If airflow increases as much as i predict I'll need to install 950 cc injectors.

Best regards
Tim Bailey

[COBB Tuning]

That is some really nice gains and I have been wondering and waiting for someone to try out E85. One question I had though and am curious if you have any insight into it. I thought it was VERY odd that there were about 4-5 pages in the owners manual about not using E85. For obvious reasons as you state above it does require tuning to make it work and if the car is only tuned from the factory for gasoline the car would not run well if at all if you put E85 in.

But the lengths at which the owners manual goes to warn against using E85 really made me wonder if there was some component in the engine or fuel system that might disagree with it to a detremental extreme? I mean they have tolerate 10-15% ethanol for gasoline since that is a common blend in parts of the coutry, but it just struck me as odd is all that they talked so much about it in the owners manual.

I know and have first hand and second hand experience with using it in Subarus for 3-4 years now and it works great so I am sold on the stuff just a bit apprehensive about trying it out in the GTR yet.

It is true that these cars were not designed for E85 fuels. However, as you said, Subaru and Mitsubishi Evo where also not designed for E85 but its use is common with few negative consequences. Installing a fuel system with ~30% greater fuel capacity is just part of the required changes to the car. This is easy and relatively inexpensive (injectors, two fuel pumps). Creating a calibration that works with E85 is also not a problem. The AccessPORT and associated tuning tools make this easy.

Because we know that the fuel components of these cars were not designed for ethanol fuels it is likely that some components will suffer. Clearly i think the benefits are worth the risks. I'm willing to bet that any fuel system degradation will be minor, repairable or preventable.

Regards
Tim Bailey

[gotboost]

kinda like this?

Very much like that but with the OEM downpipes and less boost.

This post has been edited by gotboost: Jan 17 2010, 03:58 AM

[celsius]

It is true that these cars were not designed for E85 fuels. However, as you said, Subaru and Mitsubishi Evo where also not designed for E85 but its use is common with few negative consequences. Installing a fuel system with ~30% greater fuel capacity is just part of the required changes to the car. This is easy and relatively inexpensive (injectors, two fuel pumps). Creating a calibration that works with E85 is also not a problem. The AccessPORT and associated tuning tools make this easy.

Because we know that the fuel components of these cars were not designed for ethanol fuels it is likely that some components will suffer. Clearly i think the benefits are worth the risks. I'm willing to bet that any fuel system degradation will be minor, repairable or preventable.

Regards
Tim Bailey

Tim, are you guys using twin Walbro GSS341's? Those are REALLY inexpensive and small. Do you have any pictures of the fuel pump basket? Maybe you could go to a "tripple" in-tank setup like some of the +1000HP supras.

This post has been edited by celsius: Jan 17 2010, 04:18 AM

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[Chris@AMS]

Awesome! I can't wait to tune some of these on E85 as well. Thanks for being the pioneer!

[Guru]

I'd like to see how you mounted the pumps in the factory assembly. Did you use 341's or 342's?

[gotboost]

I'd like to see how you mounted the pumps in the factory assembly. Did you use 341's or 342's?

We're using GSS342's. I'll be providing some pictures of the fuel pump install soon.

[gotboost]

Tim, are you guys using twin Walbro GSS341's? Those are REALLY inexpensive and small. Do you have any pictures of the fuel pump basket? Maybe you could go to a "tripple" in-tank setup like some of the +1000HP supras.

Gss342's, yes they are inexpensive and small, but they seem to do the job. They're the same pumps that are in Hing's car, and Tim calculated that at this time we're using about 67% of their capabilities.

[2020VT]

I'd like to see how you mounted the pumps in the factory assembly. Did you use 341's or 342's?

We were able to use the factory pump housing but it required some modification to the dual pump basket. The Walbro GSS342 is slightly longer along with having a larger out side diameter to it as well than the stock pumps. The factory pre-filter sock is still retained along with the factory electrical connector. Witch for the most part makes them a plug and play unit. On the next GTR install I will get a finished photo up.

Unfortunately I don't think that there is a way that one could use the factory pump unit to accommodate triple pumps with out making a whole new unit to go in the tank. At that point one would more than likely need to look at upgrading the size of the fuel line that feeds the injectors along with a higher flowing fuel pressure regulator. I would not be surprised if I will need to make an external surge tank with dual or triple 034 Bosch pumps with -8 feed line for Mr Bailey's GTR LOL. Since he has a tendency to want to go big or go home even on his daily driver.


Best regards
Dustin Harris
Lead Technician/R&D
COBB Tuning Surgeline

[gotboost]

We were able to use the factory pump housing but it required some modification to the dual pump basket. The Walbro GSS342 is slightly longer along with having a larger out side diameter to it as well than the stock pumps. The factory pre-filter sock is still retained along with the factory electrical connector. Witch for the most part makes them a plug and play unit. On the next GTR install I will get a finished photo up.

Unfortunately I don't think that there is a way that one could use the factory pump unit to accommodate triple pumps with out making a whole new unit to go in the tank. At that point one would more than likely need to look at upgrading the size of the fuel line that feeds the injectors along with a higher flowing fuel pressure regulator. I would not be surprised if I will need to make an external surge tank with dual or triple 034 Bosch pumps with -8 feed line for Mr Bailey's GTR LOL. Since he has a tendency to want to go big or go home even on his daily driver.


Best regards
Dustin Harris
Lead Technician/R&D
COBB Tuning Surgeline

Hey Dustin, you've finally made an appearance!

[Sharif@Forged]

Nice work Tim and company. E85 rocks. I only wish it was more readily available in the Atlanta area.