In our JrFuel car we run either an all iron Hemi [ it's the rule about all iron] or SBC . The 409 ci Hemi we have filled the block with plastic [ same stuff Gene Adams uses] and some holes drilled in the heads for air cooling. The 400 ci SBC we run water, no pump. Don Enriquez engine builder/tuner has run some dyno tests with water/ no water he found same engine with water it gained 20hp , no water it lost 20 hp. We think because the water gives the cylinder more support besides more even temps in the middle cyclinders. Ya I know , how much support can water give , but it might be the ring the bell idea, if you hit an iron bell it rings / vibrates . The idea is it can upset your ring seal , and that is where you can get the extra HP with better ring seal. Famous JF racers Scott and Frank Parks don't run water mostly because they lost a race because of a water leak, BUT they made their heads bigger, so big they put plastic on the outside of the intake port, but then they ground tru into the water, so since then they run dry.
Back to the Hemi story, we filled the block up to the heads , then we let it set for a few weeks , then had it machined , then we sent it to Gene Adams to put together, Gene called to tell us the cycinders were not round ?? How do you machine oval shape bores ?, Well Gene had his shop make them round , new pistons. then when raced again it ran about 2 tenths slower with the same combo [ piston heads, cam valves, only change was another 354 Hemi block [ because we broke it]. when we took it apart we found some of the pistons were skuffed in the wrist pin area not the skirts, so back to the machine shop to bore them round and the nest size, they were oval again. The machine shop said they have run inro that with another customer that changed his mind to run bigger bore pistons . Now because he had sleeves, they put in an oven to press out the sleeves, but because it was a filled block they could not pres them out , so the shop said they could bore them out to go bigger, not as big as the customer wanted, but bigger than what he had. BUT when they put a bore gauge in it they found the bores were OVAL. The only we came up with is the block filled expands with heat. Crazy Hey ?
So we put in the oven until it stopped growing , the new pistons and put it back together and when we raced again it only slowed up a tenth, not back to 7.02 like we had before. so now we are going to check the Hemi again to see if our piston guys lowered the compression. So back to racing the SBC With water. Too bad we only raced the March Meet in 2020, but we will race all four of the Heritage races this year.
