SR-71

I have converted my '88 Firebird (the build is in my sig) to run Flex Fuel. For the uninitiated, thats any mix of pure gasoline to E85. This is made possible by EBL's 8 calibration banks. Each bank is calibrated for a different percentage of ethanol, in 12% increments.

Actually, it's not a full conversion yet. When I fill the tank, I must do some math to calculate how much ethanol is in the mix, then switch the EBL to the appropriate bank using my laptop.

Next stage is to tie a GM Fuel Composition sensor to EBL, so I can read the percentage from the data stream, rather than do the math. I'll still have to switch banks.

BobR is working on a bank switch so you can swith banks without a laptop. That will help.

I'm trying to convince BobR to add logic for the Fuel Composition Sensor and Flex Fuel capability. He has agreed it won't be too hard and there's room in the firmware and calibrations to do it.

I have created an Excel spreadsheet that gives the adjustments to 7 settings and tables in EBL to handle high mixtures of ethanol. I have a modification to make to it. Then I'll post it here.

All that is needed is to change these entries--

• Closed Loop - Stoich AFR
• Closed Loop - Idle Lean Limit
• Closed Loop - Max Lean AFR
• PE AFR Commanded table
• Open Loop AFR vs RPM vs VAC
• Hwy AFR vs MAP
• Open Loop - AFR Multiplier vs CTS

My results so far, with my build--

• Lowered MPG, but....
• Lowered "cost per mile"
• Significant increase in power output

Problems I'm still working on--

• "Open Loop - AFR Multiplier vs CTS" settings. But I didn't have this right for pure gas yet, anyway. It's too lean until engine temp gets up to about 100 F.
• Found out I need a higher-volume fuel pump and larger injectors. Those will come over the winter.
• Could use higher compression, noticeable at lower RPMs. I'll solve this by increasing the dynamic compression ratio with Rhoads lifters.

And a "by the way" to any naysayers about ethanol conversion-- No corrosion or seal deterioration has been observed. Don't mistake "ethanol" for "methanol." They are related, but also way different. I've had several tanks of pure E85 through it now. All I can say is, it's running sweet!

SR-71

Here is the spreadsheet. It must be unzipped.

1. Copy & Paste "pure gas" values from TunerPro tables into the BLUE cells.
2. Enter the percent of Ethanol in your fuel to cell B6.
3. Enter a value for "AFR Change per % Ethanol" into cell E6. A suggested range and a default value are supplied. I believe this will vary depending on your build. Mine prefers a "leaner" setting.
4. Copy the new values from the gold cells to TunerPro.

The "AFR Change per % Ethanol" is a constant calculated from the stoich / best power / best economy AFRs for pure gas and pure ethanol. The spreadsheet uses this value and the percent ethanol value entered to calculate the new values.

On my build, it appears that the "Hwy AFR vs MAP" calculation may need some adjustment. This morning at steady cruise, my O2 sensor was reading toward the rich end of the scale, even though it was in "Lean Cruise" mode.

Experience (of others, not mine) seems to show that ethanol mixes are happy with the same spark advance settings as pure gas at part throttle. At full throttle, only a small increase in spark advance is needed.

Since ethanol cools the intake charge more than gasoline does, and E85 octane is usually 105, it's very easy to over-advance the ignition timing. You can advance the timing to the point that the force of the burn actually pushes against the rising piston, with no knock. The result is a power loss.

SR-71

Apparently the ThirdGen.org file system doesn't allow spreadsheets, even in ZIP format. The attachment is broken. This link will download the spreadsheet from my own web site.

http://www.newcovenant.com/Portals/0...djustments.xls

Zipdrive

Well this is an interesting conversion. What static compression are you running? Have you dyno'ed the engine? That would be some very valuable information.
Keep going!

Tom.

SR-71

Static compression is 9.3. No dyno available in my area, at least not that I have found that is affordable. The "feel" of the engine says it matches very closely what I "built" in Dyno2000. That's about 370 horses and 460 ft-lbs. As my sig says, I built it for torque, not max horses. My "feel" is based on driving a lot of machines over a lot of years. For lack of a dyno, the strip will tell the tale, but it needs a new transmission first.

Winter upgrades will be a "stage 3" 700R4 build (will take up to 900 horses), Rhoads lifters (will raise the dynamic compression from 7.8 to 8.9 in the lower RPMs), possibly a roller cam with the same specs as the flat-tappet that's in there now.

Also, the spreadsheet I uploaded has now been upgraded again. There is no need to adjust the "Open Loop - AFR Multiplier vs CTS" table for ethanol. So, if anybody has already downloaded it, go to the link and get it again.

Ronny

iTrader: (1)

Hot Rod Mag came in mail today. In depth article on E85....

SR-71

If anyone is still following this thread, I have greatly improved the math in my spreadsheet for calculating AFR for varying gas/ethanol blends. The "AFR Change per % Ethanol" constant has been removed. The non-editable constant is now calculated from real chemistry and physics.

To reiterate, I build 8 calibrations for my EBL, in ethanol-mix steps of 12%. I switch calibrations manually when I fill up, to match the actual percent ethanol in the tank. This doesn't happen very often, as I usually run E85 tank after tank 9 months of the year.

The values from the spreadsheet produce very good starting points for tuning ethanol blends. As is normal, some tweaking will improve individual cars' results.

You can download the improved spreadsheet here--
http://www.newcovenant.com/Portals/0...Adjustment.xls

To make my 406 happier when cold starting with E85 in cold weather, and to make more power and mpg, I will be installing thinner head gaskets to up the static compression ratio from 9.14 to 9.5. Also a set of Rhoads V-Max variable lifters to raise the dynamic compression from its present constant value of 8.1, to varying from 9.1 (at idle) to 8.5 (3500 rpm and up). Should be a very noticeable power increase.

I have been able to get the mpg reduction from gas to E85 down to less than 15%. Since E85 in my area sells for around 25% less than pure gasoline, I get the best of all worlds. The power increase of ethanol AND lower cost per mile.

dimented24x7

iTrader: (2)

The only thing you need to be aware of is that E85 has an affinity for water since it has ethanol in it. Over time, it can lead to rust formation in the fuel system.

SR-71

Actually, I haven't found that to be a problem, either. If the water in the fuel is "tied up" with the ethanol, it can't corrode surrounding pieces. Yes, ethanol blends will attract water. However, in my experience, that's more of a problem with E10 (which most everybody gets nowadays) than it is with E85.

For example, I got some bad E10 fuel in my boat. Mix 2-stroke oil with "wet" E10, and the water drops out. That will stop a carbureted 2-stroke outboard in its tracks! To get rid of the bad fuel, I drained the boat tank into my '03 Tahoe's tank of E85. No problems. The high ethanol level soaked up the water and all was well. The Tahoe was perfectly happy.

If you're going to have your vehicle parked long enough to develop fuel system rust, then you need to 1) fill the tank FULL with gas, and 2) put in a fuel stabilizer. Or drain the fuel system completely.

Fuel system rust can happen with straight gas, if you buy off-brand gas or keep a vehicle parked long-term in a relatively high humidity area (say, in eastern Texas as opposed to western Arizona).

It takes a LOT of water to cause problems with E85. The first problem you get with water in E85 is a drop in mpg and power, yet it still "runs" just fine. This happens long before rust can become an issue.

The ONLY problem I have ever had with ethanol happened when my Mallory fuel pressure regulator was brand new. E10 fuel literally melted its diaphragm. Mallory said, "Oops! Our bad!", and sent me a replacement diaphragm free of charge. No problems of any kind since then.

Mathias

Great. Thanks alot for your work, i have used the previous spreadsheet as a base setting when tuning my van running E85.

Still have some cold start issues to address and i guess your new spreadsheet will help me.

SR-71

I've found the toughest thing to tune for, E85 or gas, is cold starting and warmup. I'm still working on it. The trouble as I see it, is that you can't keep the engine cold long enough to really determine what is happening. The silly things insist on getting warm.

Also, cold start with E85 is best helped with higher compression. Part of the reason for the adjustments I'm making to my build with head gaskets and lifters.

Mathias

I know what you are talking about, i have it cold starting good enough so far, but the outside temp is still around 8-10 C and it will get lower.. but E85 goes to E75 during winter here in Sweden, just because FlexFuel vehicles have cold start problems.

305sbc

iTrader: (3)

Anyone heard from SR-71 lately?
I may have some questions about the project.
First thing I'd ask is how in the world you get 9.3:1 compression with 416 heads on a 406cid engine ??

I'm just curious about this project.

SR-71

I'm here. Just been pushed off too many other directions, rather than able to work on my 'Bird.

When I got the 406, it was a fresh rebuild with all-new Eagle components-- pistons, rods, and crank. It had long 5.7" rods (stock is 5.565") and "high pin" pistons to match the rods. But otherwise, the pistons were stock style, with 24 cc dishes, and their tops were flush with the cylinder bores. I did a full port and polish on the heads, and running "only" 1.94" and 1.50" Ferrea valves (In my opinion, the best-flowing valves you can get.).

Anyway, I had the same question. How to get 9.3:1 compression? The answer for my build is Fel-Pro #1044 head gaskets. 4.2" bore and 0.051" compressed thickness. With the 24 cc pistons and 54 cc head chambers-- 9.3:1.

With the stock 305 at 9.3:1, I had to run premium fuel. With this 406 at the same ratio, I can run 87-octane regular unleaded. That had me worried for a while, thinking I had miscalculated the compression ratio. But the real reason is that with the dish-top pistons, the smaller-diameter head chambers, and the thicker head gasket, there is apparently a lot of turbulence in there. High turbulence in the chamber means less knock.

SR-71

Just to tell other guys what this build is for. If you copy what I have done, you may not get what you expect.

Time has passed since I started this thread, and I have had fuel-pressure issues with the TBI, trying to get enough flow when using E85. I have to confess, I've gotten tired of working on it. I just want to drive it. I pulled the Edelbrock Performer RPM manifold off the shelf, and found a great deal on an Edelbrock Thunder AVS carb.

I am keeping the EBL ECM, and the electronic distributor. I will use the EBL to fine-tune the carb, so it idles at 14.5:1, cruises the highway at about 15.2:1, and hits the best power mixture this build will like. I doubt I will notice any loss of performance. The only down-side is, it won't be flex-fuel any more.

I built this car for street and highway, not racing. So I'm running a fairly mild Comp cam (212/218) with Rhoads lifters. That's a torque cam when in something as big as a 406. The Rhoads raise the dynamic compression, and the torque output line is almost flat from off-idle to 4000 rpm.

I have decided to keep the T-5 until I break it somehow. So far, it has held up to all the abuse I've given it. But I haven't run it much with sticky tires, either. It's one with the 0.61 overdrive gear option. I have kept the 3.08 rear gears, too. That means at 75 mph, the tach is sitting just under 2000. The 406 with torque cam timing and Rhoads lifters can launch the car just fine with that steep gearing.

For best performance, I have to shift at about 5200, because the heads run out of flow just above that. But this thing accelerates like a bullet from the moment you press the gas, at any speed.

Lots of guys wouldn't like how this is built. I could make it run ET's in the 10's, ruin its fuel economy and kill its pleasure on the street. But for me, how I've built it makes it a blast to drive down the road. I really don't care about ET's (though it is in the low 12's). Truth is, it has out-accelerated everything I've gone up against. Computer modeling still claims a top speed over 180 (which I'll probably never get to try). And it gets 31 mpg at 75 mph down the interstate.

I have an updated link to that spreadsheet for tuning the EBL for flex-fuel:
Ethanol_Blend_AFR_Adjustment.xls

Right now, she's up on stands, waiting for me to put in a new clutch disc. Her suspension is complete, lowered 2 inches, full set of polyurethane bushings, and adjustable axle centering. Interior is about 90% done. I want to do some cushioned vinyl covering over the hard plastic, and put a new boot on the shifter.

Here's a shot of setting up the carb. I have to re-do the fuel lines to fit it, but use the same pump and pressure regulator.



Then come spring, it's a full strip and repaint. I hope to come up with a good way to take a 3rd-gen hood bird design, enlarge it to fill the hood lengthwise, with the wings extending over to the doors, all in a ghost effect. I can'd decide which color to use on the black. I'll post that question on a new thread later.

mhelander

Thanks SR-71 for updating chart.

I re-calculated my TBI 2011 maps using chart and it seems that now all calculations are making values for richer side than previous version.

Also my TunerPro lists temps, RPM etc in reversed order, and some titles are different. So here is my modified version in Google Docs, available for download or copying for personal use.

SR-71

That chart of mine hasn't been modified in a long, long time. Also I haven't downloaded and installed the latest EBL updates. There have been several updates in the past where tables get reversed, and some mixture-handling calculations get changed. Always good, but sometimes unexpected.

There are probably several version differences between our EBL's. But you're getting it done.

RBob

iTrader: (1)

The change was between V4 and V5 of Tuner Pro. The column order is different. In V5 the column ordering can be changed back to be the same as V4:

Tools->Preferences...->General tab->Table Editor Options->Reverse Rows check box.

Note that the "Crank - AFR" table should be added to the SS. The reason it is OK without changing it, is that the ECM will use the richer of the two: the crank table value or the open loop value.

But this will likely cause some extended crank times.

RBob.

mhelander

Thanks Bob, table above added to my version of the spreadsheet. Will try it out too.

mhelander

It might happen .

Spent about two hours driving for VE learning after merging spreadsheet values to my latest learned bin. It feels better, idle is less rough when open loop. But engine was almost fully warm when started so let's see...

As Bob suggested, I hadn't modified "Crank - AFR" table, that's next.

benheinzeroth

Please provide an updated link for your lastest revision adjustment file!