Aero improvements for my old race car; whizzing up a rope?

800lb gorilla? It's more like 800 ton.

I'm not looking to absolutely run at the front. The modified exhaust and a few other tweaks will likely add 10-15hp. There's 40-50lbs coming out of the car along with the proposed aero improvements.

The key with the aero stuff is I either have the parts or I can make them myself cheaply. As noted these could be equivalent to 5-7hp. The weight savings is free and I have most of the parts for the exhaust, so it's just paying to have it all welded up.

By contrast doing the motor work beyond where it is now will rack up the dollars in a hurry. The options are larger valves, which going beyond what's in there now will require new seats, machining valves & block and adding lash caps or buying $400 worth of valves, all to get 1mm bigger valves. The bore can be enlarged but that will be $500-600 worth of custom pistons along with boring the block. A cam change could be done for as little as $150 but this will run the powerband up into the zone where a close ratio box will be an absolute necessity (I have a close ratio boxes but they aren't up to the motor in the car now) . It will also mean much more frequent motor rebuilds.

The whole idea is to get a little bit more out of the car without spending a fortune. A full race motor will be 155 whp but this will still be 10hp shy of what's needed to compete against the front running 2.0 liter cars. So what I'm looking at is spending $500 tops to get up to 5-6th overall or spend another $5,0000 to $7,000 to run 3rd or 4th overall. For 7K I could buy a send F500 for my son to race with me or buy a old Sports Renault and be on pole in the small bore group.

Just to give some context, since 1984 we've invested 9K in the car. I'm getting ready to sell $1000 to $1500 worth of parts so that will take the cost of the car down to as little as $7500..........most of the people I'm finishing just ahead of or just behind have spent more than this on the engine alone.

In reply to Tom1200: You want some free horsepower? Start using E85.. Here's why, it should be good for a serious increase in power and yet it's pump gas so it's legal..

First don't believe me? Check out the testing this magazine did with a Miata that wasn't all that far from stock.. Alcohol adds power!!! Back in the early 1960's Ford Motor company found that using alcohol over gas got them 22% more power. Indy cars use pure alcohol. while NASCAR uses 30% alcohol. In drag racing using alcohol moves you up a class..

Pure alcohol made something like 15 extra horsepower while I think E85 made only 8 more... (in about a 100 horsepower motor) Yes, they tested race gas and 93 octane etc.. seriously read the article!!

How? Ethanol is 114 octane and has an extra oxygen molecule in it which means you get to richen it up. The more fuel you can burn the more power you make..

Now I just paid $1.50 a gallon for it in my truck while unleaded is up at $2.20 a gallon.. (OK, $1.49.9 & $2.19.9) It's a flex fuel option but wow! Does it make that pickup fly!!! It seems like an extra 100 horsepower but probably closer to 50..

Yes in my pickup I get worse gas mileage.. Instead of 22.3 with 87 octane I'm down at 20.8 with E85 {when I can keep my foot out of it} which isn't all that often. Only 12,000 miles on it from new but already the back tires show 2/32nds more wear than the fronts..

In short if I use nothing but E85 I will save well over $200 a year on my gas bill covering the same distance..

Back your car, Since you have carbs, you will need to richen the jets.. It's relatively easy.. E85 needs about 60% more fuel. If you like the math the formula should be easy, if like me you are a hands on guy rig up a simple Tank-Jet-catch tank/ stop watch arrangement. and over the same amount of time keep drilling out the jet using bigger and bigger drill bits until it flows 60% more. You will also find that you can run a little more timing and the engine will run a little cooler.. (not to mention not loading up your spark plugs as easily and keeping the combustion chamber cleaner)..

Now about the pump fuel part.. E85 from the gas station pumps will be anywhere from 30% alcohol to 85% alcohol.. and the real problem is the base stock.. With ethanol at 114 octane and the pump rating of ethanol at 88 octane makes you wonder what sort of asphalt (er.. gas) they are adding to the ethanol doesn't it? So you can buy E85 in 5 gallon cans and 55 gallon barrels from racing gas suppliers.. There at least it's controlled and reliable..