: Tweaking the LT1 for better use on E85

02-22-08, 06:56 PM
This is intended to be a technical discussion, not a pro/con of E85 or the political ramifications (you don't like it? See your favorite politician, they probably are the ones who signed the legislation, feel free to abuse them). I am not proposing that everyone go out and pump E85 in their Cadillac's. Don't do it until you are fully understanding what is going on. Can it be done? Oh yes, easily. But failure to pay attention to details, will cause engine damage.

I have been running my 94 Fleetwood LT1 on E85 for quite some time, but hit a brick wall with cold temps (30F and colder) with poor mpg. Drivability is ok, but mpg <14. Was in the 16-17 range when warmer. Power is always improved significantly with E85. You really feel good at WOT, part throttle is also nice and healthy feeling. Note I tune my own car, and have my tune loosely based on the 94 Corvette timing maps with some additional tweaking. This gives me a pretty nice 93 to E85 tune that I don't have to fuss with too much to run E85 long term.

So, after doing some book reading (1980 is the year of all the books at the library, check out all books you can find on Ethanol and Methanol, much of what applies to Methanol (M85 or M100) applies to Ethanol (E85 or E100) but not so bad on Ethanol. But what I found was significant improvements in mpg resulted once the fuel and air into the engine was heated. Colder wasn't better. The latent heat of vaporization in ethanol is very different than gas. I always asked WHY E85? Why not E100? Or E95? Well, that was the answer. They add more gasoline, not just any gasoline, very very high RVP gas to the ethanol mix. So it is not simply pump gas mixed with ethanol. So in the carbonator engine, 1.7L VW in a Dodge Omni/Horizon. With a mechanical distributor, 29 degrees ignition advance (Best guess on that is 29+initial), they were getting 35 mpg on pure ethanol (E100).

In my experience in the LT1. We run 180F stats, and the heads cooler than the block. The engine is ingesting outside air (even without air box, the air moving outside gets in with sufficent quantity that no airbox once moving pretty much sees only 2-4 degrees warmer than ambient air.

The Omni/Horizon experiment they made it heat the intake air and they built a tank to warm the ethanol under the hood with the antifreeze cooling system. This mod was the most significant to them for improving cold drivability and side benefit mpg got nearly that of gas. Once they tore down engine for further inspection (had an issue that wasn't ethanol related) they bumped compression up to 11:1. At this time they exceeded gas mpg with ethanol. The goal was 13:1, but it feesable to do with the VW 1.7L engine.

I am thinking of experimenting with trying to heat my fuel lines with a copper pipe wrapping my fuel lines as far back as practical, 6 or so feet. Wrapping it in hot water pipe insulation (obviously taking great care around the exhaust). And then change the air inlet to draw in air across the exhaust manifolds or through the radiator to provide a controlled hot air intake charge. Sorta like the thermac days on the Q-Jets... It maintained at least a 100F intake air charge depending on the car model.

Thoughts? Ideas? Anyone ever get into the experimental sides of things?

02-22-08, 07:05 PM
Another interesting article in one of the books was on Methanol. They ran a 10% mix of gas and Methanol and saw a reported 15% boost in power AND fuel economy. They did NOT however, note the type engine, but it is likely to be carb'd (1980). There were pretty much no negatives on Methanol except the cost. Rumors are $4-$5 a gallon street price (2007 reports from individuals who are messing with it, purchasing at local tracks)

Methanol is an interesting fuel. Harsh, but yet, seems chemically to be very clean once burned. But not burned, somewhat toxic. And M100, burns clear. It is dangerous if on the skin and can be absorbed if not removed immediately. MTBE was Methanol related. These articles were written long before we found the MTBE issues.

03-25-08, 02:21 PM
Did you upgrade anything in your fuel system (filter, lines, injectors, gas tank even) to handle E85? I know there's some concern about how E85 is more corrosive than regular gasoline - and a proper E85 conversion not only involves tuning but upgrading your fuel system to handle the different material.

Just started reading up on ethanol today - from what I understand (on a basic level) there is some interesting opportunity here, since ethanol kind of "comes with its own oxygen". Some people have had some great results running mixes of E85/regular gasoline (like 30/70%) because it causes the mixture to lean out a bit, compensating for the tendency of cars to run rich off the factory.

Without a good tune I probably would never try this on my Fleetwood with the L05 - I found something in the FSM about how the ECU has a "highway mode" that would run the mixture leaner than normal to improve fuel economy. I can imagine even a small ratio of E85 can start to mess that up real good.

03-25-08, 02:35 PM
Totally honestly, no, nothing needed it. I think most EFI cars from at 92 or so on up are ok, look at the fuel pump more than anything for a rubber line, the 91's did have rubber, might be ok, but still that would suspect me to get in and replace it. All now have plastic inside.

The tank is steel, the pump has plastic lines, the car has plastic lines, the filter is steel, the FPR has rubber, but good for 10% ethanol and I highly suspect if you are good for 10%, you are good for 100%, the fuel rails are aluminum, the FPR mount and lines are steel, the injectors are plastic and stainless, the o-rings are same for just about anything (mine are 01 LS6 injectors).

The bad rap that methanol and ethanol have is back in the "old days" they used something like roof tar to coat the insides of the gas tanks. That was easily eaten by the alky. Ford uses stainless fuel lines, but they do on non E85 cars too. I have run at LEAST 20K on E85 now, and STILL not any evidence of problems. Stock fuel filter too.

I replaced the pump in my 99 Burb and it got occaisional E85 and the tank was beautiful clean inside. Nothing bad at all. I run 100% E85 in it too now. I can tune 96-07 GM vehicles now (most all V8 and some v6 non N*), so am working on optimizing my 454 on E85... It likes it too.

Alky likes to eat certain materials, I had a list at home, I'll have to look again for it. Many confuse Methanol's characteristics with Ethanol, ethanol is far less corrosive than Methanol. But overall both are generally much safer than gas in almost every case.

03-26-08, 10:31 PM
This is very interesting. I had lunch with Chad about a month ago, he was telling me about a Suburban I believe, that they had repaired at his dealership, where the owner had accidentally filled up on E85 and it corroded the injectors. Maybe he'll chime in, he could tell you all the details, but frankly, I'd be interested to look into this. I'm only driving between 400 and 500 miles a week right now, but I'm still spending more than I'd like on gas.

03-27-08, 03:50 PM
Oh, there wasn't any E85 in his gas...our reading was off. But if there had been E85 in his gasoline (it was an '01 K2500 with the 8100) it would have eaten up all the rubber components in the fuel system due to the higher acidic content of the E-85.

03-30-08, 03:40 PM
Ethanol is far from acidic. It has some corrosive properties, but to lead (remember the old brass floats with lead based solder?) and non achohol based rubbers. Methanol is somewhat harsh on aluminum, but not ethanol.

If my 99 K2500 Suburban and my 94 LT1 are solid and fine with E85, an 01 is very likely fine with it. Look at our LT1's, we have a fuel pump, plastic fuel line from the pump to the top of tank, plastic lines from tank to filter, metal filter, plastic line from filter to FPR, steel lines at FPR and then aluminum fuel rails. The 99 K2500 Burb is very similar.

E85 won't corrode injectors, they either screwed/scammed him or there was something else going on that E85 had nothing to do with. I have 30K or so miles on mine. NO issues.

If you every end up accidentally filling with E85 and the car isn't, simply drive on it, don't let it sit (older cars are more sucptable to issues, mainly pre-1985 or so, probably more like pre-1980. Pretty much once the stations started getting 10% ethanol or 15% MTBE the car manfs HAD to step up and put in the right floats and rubbers) for long. The car will run poorly for a short time, and WILL have some cold start issues (in cold weather, 40F and colder). So run as much as you can down that day, and if you can fill it up with gas again, that will help get the % of ethanol down. Avoid WOT or heavy loads, these are higher risks for leanout. The PCM will correct and it will run fine.. But might throw a code (note that 96-up GM most likely WILL toss a lean code, but that is ok).

04-04-08, 08:10 PM
So are the injectors in a stock LT-1 any different than the LS1 injectors you have in yours, as far as materials? I'd really like to give this a try but I'm hesitant, obviously, because of the fear of completely screwing something up. So what you're saying Tom, is right now, I could tune my LT-1, fill my tank with E85, and drive around with better mileage and lower fuel costs?

04-06-08, 02:16 AM
I am running stock LS6 injectors, they are the same flow rate as LT1. LS1 is NOT the same flow rate as LT1 or LS6 for 97-00, 01-up they all shared the same injectors. I picked them up initially because I was told via internet info that they were 28.5 lb/hr injectors. But come to find out, it was simply bad info....

Well, you CAN run it and not hurt it as long as you avoid WOT or heavy throttle. It will potentially lean out as the injectors really need to be in the 40-45 lb/hr range. I datalog often while driving mine with E85, so I am pretty aware of it.

I tuned my friend's 94 to not fault out on E85, but not too much more than the basic tune I do (starting to get into tuning finally!!) and he got mid 18's on the highway running 50% E85 and 50% 87 octane. And he is getting 16ish city. He is very happy with that. So he should do better with pure gas, but is getting same mpg with 50% E85 than he did on pure gas with stock tune. So I guess that tune did him some good for sure, he is pretty happy.

Tuning it helps, I run 100% E85, but can run it on gas, but have to run 93 octane if running gas due to the timing increase. But that is the closest to an efficient dual fuel vehicle I can do right now. Hope to do more later, but need something to scale the BLM/LTFT when E85 is present to be most efficient.

04-06-08, 10:03 PM
Hmmmm, good info.....so theoretically, what about going to a full E-85 setup, no gas? I would have no problems finding gas stations that sell it up here.

04-06-08, 11:25 PM
The fallback fuel would have to be 93 octane, I haven't risked 87 octane on a E85 tune yet. I might try it and see how it does.

If you have lots of E85 around, I would go for it for sure. It sure saves some on the pocketbook if the price is right. I have found though, honestly, I need to see in the $0.50 range cheaper for E85 and it becomes worth it. I have a friend who is running 50% E85 on my std tune and he is seeing 16's for mpg, city only, he is seeing 18-18.5 highway. I am running my own tune with 100% E85 and seeing 15-16 city/highway.

04-12-08, 09:22 AM
So to clarify, running E85 on the stock tune is possible as long as WOT is avoided. Running a 50/50 of E85 and premium is a good way to keep mileage decent, and running a tune with 100% E85 is a good way to keep costs down. Am I getting this?

04-13-08, 08:49 AM
I tuned a friend of mine's 94 FW and he just called me from his trip to Ohio and back this weekend and on 50% E85 50% 87 octane he is getting mid 19's there and 20 something on the way back. Been getting 17's combo city/highway, mostly city.

So if you mix E85, just use 87 octane, as it will still bring it up nicely to an premium octane level. You may/may not get check engine light, as it will be on the lean side.

I honestly feel that the mix is pretty good to do, probably the best compromise for mpg and power and fuel costs.

To put it in perspective on how much it costs?

For 400 miles driven on E85: I am getting between 16 and 17.7 mpg on pure E85, that is around and average of 24.24 gallons needed to go 400 miles. @ 2.599 a gallon, that is $63.
For 400 miles driven on 87 octane: I was getting no better than 19.5, so that is 20.5 gallons needed to go 400 miles, @ 3.459 that is $70.95. So using my typically best mpg on gas and average on E85, I STILL save pretty good $$. I might see some drop in mpg as we get on summer blend E85 (winter blend is E70ish).

Remember, I drive around 600-800 miles a week (if I work all 5 days at work, that is 150 miles round trip a day x 5 days, 750 miles....) that is adding up pretty fast.

But ideally, to run E85 you should go with it tuned, to run 50% E85, just GOOD premium octane tune, with some other tweaks that keep things running good and happy. I have a solid tune for 50% E85, pure E85 and can do probably anything in between.....

ANYTHING you can do to ingest warmer intake air will boost mpg on gas or E85, and more so on E85. I actually am running MAFLess/SD mode again, running 2 90 degree 3" PVC bends and a air filter that fit it (I have no idea what PN anymore!) and have it sitting over the driver's side exhaust manifold. That alone was a help to mpg.

So really it wouldn't even take too long for running 50% or pure E85 to pay for itself over the cost of the tune, and you get extra goodies in the tune too!

05-15-08, 10:35 AM
So, just to clarify:

I can fill up my stock 1996 Roadmaster with E85 and drive it in normal, around town conditions and not have any adverse side effects other than hard starting in the winter?

just change out the fuel filter after the first few tanks?

I'm not looking for performance, just relief from $3.76 a gallon gasoline.

05-15-08, 11:17 AM
A friend of mine is running 50% E85 on his 94 FW and getting 16 mpg city with very little highway. You likely will get a check engine light for LTFT too high (lean), but the O2's will NOT be reporting lean, only the LTFT will be pretty high. Normal driving will be fine, to do much more, it would be adviseable to install larger injectors, and or do PCM tuning. I have run stock flow rate injectors with E85 for some time now with zero ill effects. Not one time indications of being lean (even to 133 mph....:)

Can you do it? Should be able to, watch it closely, get a datalogger on it (like FreeScan and a cable from Moates, AKM Cables or PCMPerformance) and look for lean conditions on the O2's. My experience is you won't have any issues, but reality says be prudent and monitor it.

Honestly, my PCM tuning has got me 16-16.5 average (15.2-17.7 overall actual max/mins) mpg with pure E85 combo city/highway, a good 50/50 mix of it. Note my car is a tow package car and I have never got over 22 mpg yet (suspect transmission is my holdback on mpg, but then again, at 250K miles it is still solid as a rock!).

05-15-08, 12:13 PM
I'll give some history behind this Roadmaster Estate:

It's a 1996 with 56,000 miles on it. A friend of mine bought it for $750 at the Goodwill auto auction with 44,000 miles on the clock. The previous owner had smacked the front end into a pole. The interior is basically immaculate and there was only bumper, fender, and hood damage.

My friend bought the front end off a sedan that had been wrecked in the rear and we rebuilt it.

I am using as an apartment maintenance vehicle that replaced a 2003 Chevy Avalanche till I move Germany. So it's primary duty is just hauling tools around town at fairly low speeds. 2,500 RPM is a busy day for this car. It also has the towing package. I'm getting terrible mileage right now, but hope to correct that soon with some basic maintenance items that have been neglected.

Pictures of the rebuild process can be found at Rebuilding the Battlewagon (http://rebuildingthebattlewagon.blogspot.com)