Ethanol varnish residue: Carb vs EFI

We run Sta-Bil in all of our small engine stuff with mid grade/89 E10 from a major supplier like Shell, and it usually keeps the hassle to a minimum. I also run sea foam at least once a year through all of it, which helps a ton as well. Come to think of it, it's probably that time of year again. I know the octane doesn't make much difference on the small engines, but I believe it usually has more detergents to help dissolve stuff better.
I fill about 8 gallons of gas cans at a time, which lasts maybe a month in the summer and 3-4 months in the winter on a zero turn, a push mower, a trimmer and a chainsaw on a half acre lot, just for full context. Too much consumed for the little cans, but not so much that I know the gas will be used every month for sure, and I don't want to have to deal with managing inventory. If you have stuff clogging in weeks, I think it's another issue. I'd probably dump out everything you have (or pour it into a modern car* in reasonable amounts, they can adapt for wildly different fuel quality) and start fresh, finding your problem while making sure some residue from your old can or something isn't causing the issue.

Bennyt said:

I've never thought of using e85 for towing during the summer. Might be something to consider. My Suburban was a flex fuel and whenever I used e85, it dropped the mpg by 20-30%. Had a few friends with similar experiences.

We used to have a HHR SS which is probably one of the most powerful production cars ever built HP per CI. 2.0 liter over 300hp w/ GM tune. Mine was supposedly over 325 with 23psi and K&N intake. I never ran it with ethanol but the tune had a setting for e85 and e47 where it would up the boost a few more pounds.

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Its a respectable HP/CI... but nowhere near the best. It used the Cobalt SS motor and had the same power rating which was 260hp. The competitors at the time were the Neon SRT-4 and WRX STI's which were making the same or better power, but with a 2.4 or 2.5L I-4. My 2005 SRT-4 was rated at 230hp.. but that was at the wheels. It was about 260hp at the crank. You could get a Stage 1,2, or 3 kit from Mopar that would bump that all the way up to 260hp at the wheels in Stage 2 and 355hp in Stage 3 trim and high octane mode. I had a custom turbo, manifold, and intercooler on mine and used aftermarket injectors and a Mopar Stage 2 computer. It dyno'd at 380hp to the wheels in street mode, 91 Octane, and 21lbs of boost. Hit 471hp on the dyno with 100 Octane, high octane mode selected, and 24lbs of boost. That was all on completely stock internals for several years. I finally put it all back to stock and sold it in California when I moved back there after I got out of the army. It would have probably been able to make an extra 100hp or so on E85, but this was back before you could really get it anywhere.

A drop in MPG in regular driving of 20-30% with no additional tuning having been done to the vehicle is pretty standard. The drop in MPG is a bit less pronounced when doing heavy duty stuff like towing, and the big thing to note is that the cost per gallon is right around 17-30% LESS per gallon for E85, so it really averages out when you are looking at PRICE per mile. So for the same price, you might have to fuel up more often, but you make more power, the engine runs cooler, and you don't have to worry about blowing the engine up.

This is a screenshot from a website looking at gas prices in Texas, so this an average across the whole state. The spread in price is more pronounced in areas with more available stations and less in areas that don't have it. But overall across the whole state ~17% cheaper to buy E85.

Bextreme04 said:

It used the Cobalt SS motor and had the same power rating which was 260hp. The competitors at the time were the Neon SRT-4 and WRX STI's which were making the same or better power, but with a 2.4 or 2.5L I-4. My 2005 SRT-4 was rated at 230hp.. but that was at the wheels. It was about 260hp at the crank.

A drop in MPG in regular driving of 20-30% with no additional tuning having been done to the vehicle is pretty standard. The drop in MPG is a bit less pronounced when doing heavy duty stuff like towing, and the big thing to note is that the cost per gallon is right around 17-30% LESS per gallon for E85, so it really averages out when you are looking at PRICE per mile. So for the same price, you might have to fuel up more often, but you make more power, the engine runs cooler, and you don't have to worry about blowing the engine up.

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Dealers charged $300 to unlock the "competition" tune on the HHR/ Cobalt SS which I assume almost everyone did. It took it from 16 psi to 23 auto/25 manual adding 63/ 81 hp all under factory warranty. Other than adding the K&N intake, I left mine stock so close to 335 hp. It did overheat d/t malfunctioning fan and cracked the styrofoam mold block block but I was able to order the euro spec Opel motor pretty cheap which was another 20 hp d/t better injectors. Mine was a 09 but in 10 they switched to a traditional sand cast mold. Unfortunately, mine was just out of warranty.

But even at 260, that's over 2.1 hp per ci. No, it's not N/A but neither is a hellcat at 1.78hp per ci. I don't know of too many production vehicles over 2 hp per ci and especially at that price range. I spoke to a GM engineer and he said the engine was underrated and originally they were all supposed to have the comp tune however it would put it pretty close to the performance of the flagship Vette and they couldn't do that.

I didn't know the SRT4's were that powerful. Sounds like a cool squirrelly ride!

On my Nova I originally I built a TT 447 SBC and was going to use ethanol to run cooler. My new motor is smaller and is supercharged but I'm not sure if I'm still going to go the e85 route. I'll see how it behaves but am definitely interested in possibly looking into doing something on the C30 for when I tow. Possibly one tank regular and one e85.

Bennyt said:

Dealers charged $300 to unlock the "competition" tune on the HHR/ Cobalt SS which I assume almost everyone did. It took it from 16 psi to 23 auto/25 manual adding 63/ 81 hp all under factory warranty. Other than adding the K&N intake, I left mine stock so close to 335 hp. It did overheat d/t malfunctioning fan and cracked the styrofoam mold block block but I was able to order the euro spec Opel motor pretty cheap which was another 20 hp d/t better injectors. Mine was a 09 but in 10 they switched to a traditional sand cast mold. Unfortunately, mine was just out of warranty.

But even at 260, that's over 2.1 hp per ci. No, it's not N/A but neither is a hellcat at 1.78hp per ci. I don't know of too many production vehicles over 2 hp per ci and especially at that price range. I spoke to a GM engineer and he said the engine was underrated and originally they were all supposed to have the comp tune however it would put it pretty close to the performance of the flagship Vette and they couldn't do that.

I didn't know the SRT4's were that powerful. Sounds like a cool squirrelly ride!

On my Nova I originally I built a TT 447 SBC and was going to use ethanol to run cooler. My new motor is smaller and is supercharged but I'm not sure if I'm still going to go the e85 route. I'll see how it behaves but am definitely interested in possibly looking into doing something on the C30 for when I tow. Possibly one tank regular and one e85.

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The biggest issue is that GM rates their engines at the crank. The dodge ratings were at the wheels. Backed up by dyno numbers... you can look at both the Mopar and HHR forums for confirmation on that. The SRT-4 in 2004 and 2005 were 2.4l or 146 cu. in. Stock setup was 230hp(likely 250-260hp crank) which is 1.57hp/cu.in... not too shabby, but not awesome either. I've seen a bunch of dyno charts from guys on the cobalt forum with aftermarket tunes on their car showing ~300hp at the wheels without needing to upgrade factory parts, 335hp at the crank would put you right there at the wheels, so seems reasonable. 2.0L is actually 122ci, which makes the hp/ci better than you stated. So that puts you at 2.1 hp/ci at the crank stock and 2.45 hp/ci at the crank. I believe they had the same thing as an option in the Pontiac Solstice.. which would be a pretty hot ride in that configuration(i think they called it the redline?).

Mopar offered the Stage 1, 2 and 3 kits through dealerships and it maintained the factory warranty as well. Stage 3 kit could put you at 355hp(at the wheels) which is about 400hp at the crank. So you could get a factory Stage 3 SRT-4 from your dealer with 2.43hp/ci at the wheels and 2.73hp/ci at the crank. Plus, since it has more displacement it makes that power(and more importantly, torque) lower in the RPM range. The max torque was 365lb-ft from 3200-4800RPM!!!

The comments about the competition with the corvette don't make any sense though. 2008-2010 corvette was no where close to even the competition tuned HHR and cobalt. Base model corvette is a 6.2L LS3 making 430hp and the ZO6 gets an LS7 making 638hp. The corvette is even a few lbs lighter than the HHR. Curb weight for a 2010 HHR SS is 3180lbs and the Corvette is 3175lbs

Maybe they were thinking about it being more than the Camaro?? But even then, the RS V6 Camaro(lowest horsepower option) is rated for 305hp.. which is still pretty dang close. The SS Camaro also got the 6.2L LS3(but detuned a hair to not be the same or more than the corvette) with 426hp. So I guess the argument they were trying to make is that chevy didn't include the competition tune because they were worried that an HHR SS would compete with a Camaro RS V6?