The Ethanol fuel makes the exhaust cleaner. Now we just have to work on cleaning up the ti
When we first introduced our Project Old-School engine build, the premise was to build an engine that would remind us of our younger days-when overkill was the way to make power. With our engine, we started out with a lot of compression, a lot of camshaft, and what we thought was a lot of carburetor. I say we thought we were over carbureted, but during our last dyno session, we noticed the power dropping off after about 5,000 rpm-a sure sign that not enough air was being moved. This really surprised us, as with two 465-cfm carburetors (totaling 930 cfm), we thought our 340 stroker definitely wouldn't need any more carburetion.
As soon as we strapped the car down and made our first pull, we found that we needed more
Over the last several months we have been able to run several gallons of race fuel through our Old-School engine, and to be honest, race fuel can get expensive. The way the engine is built, there is no way that we can simply drive to the local fuel depot and fill up the Valiant with "pump gas"-or can we? Under normal circumstances, the only fuels you can usually buy "at the pump" for use on the highway, are rated from 87 to 93 octane. With an engine running a 12.0:1 compression ratio, a tunnel ram, and a big, solid-roller camshaft, that is not an option. What is an option is running E85 through the carburetors. A couple of years ago, E85 gained a lot of popularity, but at the time, finding a local station that carried this new fuel was few and far between.
As soon as we got the new carburetors back to the shop, we started the conversion. First w
E85 has an octane rating that is higher than that of regular gasoline's typical rating of 87 through 93, and this allows it to be used in higher compression engines. Using E85, however, does have the drawback of lower fuel economy, as more fuel will be needed per unit of air (stoichiometric fuel ratio) to run the engine as opposed to traditional gasoline. This corresponds to a lower heating value (units of energy per unit mass) for E85 than gasoline. Because of the lower heating value, E85 has a cooler intake charge but a higher stability level from its higher octane rating. Use of this fuel not only results in lower GHG emissions, but typically results in a measureable percentage increase in horsepower and torque at the wheels. Because of its lower price than race fuels, and increasing availability in certain areas, the use of E85 is becoming more viable.
Simply dumping a tank full of E85 in your car and hoping for the best is not a good idea. There are a few changes that will need to be made. Now, we'll be the first to admit that we have no experience running Ethanol, so in order to avoid looking like idiots, we found someone who does know a thing or two about running E85. Darren Tedder of Prism Racing in Conyers, Georgia, told us, "We regularly see a 3-5 percent power increase simply by converting an engine from race fuel, or "pump" gasoline to clean burning, highly-oxygenated ethanol." Darren told us that several changes would need to be made to our 465-cfm carburetors before any E85 was run through them. Since E85 "burns" differently than conventional fuels, delivery of the Ethanol is handled a bit differently through the carburetor. An E85 carburetor needs to be "converted," by changing the metering plates (different emulsion-orifice properties), and possibly, some air bleed, and needle and seat changes. Normally, a needle and seat assembly with more flow capabilities might be needed, but since we were running two carburetors, he felt we would be ok.
In this photo, you can notice the differences in the metering plates. With E85's physical
Therefore, there are different emulsion properties as dictated by the orifices that can be
Once we had the carburetors ready, it was time to switch the 465s for the 650s. This requi