Baffled Racers - Sleepy's Track Tech

Have a question for Sleepy's Track Tech?

Q: We are going to run a basically stock 400-cid small-block with 194 heads and a four-barrel carb in a UMP Modified that we are building. This will be our first year racing and we are wondering if we should run gas or alcohol? We are well aware of the benefits of alcohol in high-performance engines, but will running alcohol be practical in a basically stock engine?P.S. I read SCR because of your articles.JeremyVia e-mail

Sleepy: Gee, another satisfied customer. Jeremy, if it weren't for people like you, I wouldn't be writing this. The simple answer to your question is yes. Now, let's go on to why.

First, there will be only a small performance gain with a low-compression stock engine, so raise the compression if you can. A steel shim head gasket (0.015 inch thick) will help so long as the head and block surfaces are true. Spray the gasket with high heat aluminum paint for a sealant. Done it for years, works well. Alcohol responds well to high-compression ratios. I'm told it has an octane of about 140.

So if there is little performance gain in a nearly stocker, why use it? I try to stay away from pump gas because you never know from delivery to delivery what is in it. Therefore, I buy racing gasoline-expensive, but at least it is always the same. Though race gas is about twice the cost of methanol, I prefer methanol when rules allow. An engine will use about twice as much methanol as gasoline, but methanol has a cooling advantage.

An engine will run somewhat cooler on methanol than on gas. This might be a prime consideration with a 400-cid small-block because it can be more difficult to cool than the typical 350-cid small-block. Notice also that alky-fueled cars often have a smaller radiator. This can reduce front weight by a few pounds. It is not just the weight of the radiator, but also the weight of the extra water it carries.

The only downside might be the cost of obtaining an alcohol carb. This won't be much more than getting a reworked gasoline carb. Either way, throttle response and performance will be better with a reworked carb. Take a short cut somewhere else, put worn tires on the left, do what you can, but get a good carb. A good rule of thumb for selecting a carb supplier is to find out if they have a dyno. If they don't, then thank them and go somewhere else.

A quick recap on the benefits of alcohol fuel: There's a small performance gain with a close to stock engine; alcohol loves compression; overall costs are about the same as race gas; it cools better; and requires the proper carb.

Q: Sleepy, I have two questions. I race in a class that requires an automatic tranny. Should I run a tranny cooler, and if so where do I put it? I have seen them mounted on firewalls, in front of the radiator, and inside the car. How about using the stock cooler inside the radiator?

Second question: I have heard of trannys popping out of gear. How would you suggest solving this problem? We race in low gear on a 31/48-mile paved track in the Street Stock class.RandyVia e-mail

Sleepy: Automatic transmissions with a torque converter need a cooler. When using an automatic with a direct-drive setup without a torque converter, a cooler is not important in short races. Still, a tranny cooler is never a bad idea. The torque converter is where the heat is generated. A torque converter all but shears the transmission fluid as it moves through the converter's vanes.