ryanruck
Active member
- 427
- 46
- 28
- Location
- Cincinnati, OH
Link
Good thing we've got folks here that know more than Bill Jenkins though...
ETA: Wanted to add an excerpt from Mr. Jenkins's book, "The Chevrolet Racing Engine":
Circle track cars have done this for decades... specificly SBCs with 18 degree heads. Smokey Yunick was a pioneer in this.
It helps to equalize temps between cylinders as a SBC always runs hotter on the back half. it is not a crutch or band aid it it way to increase coolant flow thru the heads to eliminante "hot spots.
Books have been devoted to this concept. Grumpy Jenkins ( RIP ) did this as well and wrote about the modification in his book.
That man forgot more about SBC than I will ever know.
Some water pumps actually come with the additional ports to add the plumbing to the heads.
I did it on my engine and no regrets.
Good thing we've got folks here that know more than Bill Jenkins though...
He was formally trained as a mechanical engineer at Cornell University, and he used his training and skills to build engines.[3] He has been inducted in numerous motorsports halls of fame for his engine building skills in the National Hot Rod Association (NHRA) Pro Stock division. His innovations include drag racing's first kickout oil pans, Pro Stock strut-style front suspension, and dry sump oiling system, and cool cans, electric water pump fan, gas port pistons, and slick-shift manual transmissions.[3] Considered the "Father of Pro Stock", Jenkins-built engines were used to win five NHRA Pro Stock championships and three American Hot Rod Association (AHRA) championships.[4]
ETA: Wanted to add an excerpt from Mr. Jenkins's book, "The Chevrolet Racing Engine":
INTRODUCTION
In the beginning we should make it clear what we intend to give to the readers of this book. The information herein is the result of more than twenty years racing experience with the smallblock Chevrolet V8 engine and it is intended as a basic study of racing engine design and assembly. The illustrations show typical techniques and hardware developed at Jenkins Competition for our own drag racing and Nascar stock car engines. Currently, we are talking about power levels of about 670 horsepower from our 330 cubic inch displacement Pro Stock drag motors and 580 horsepower from our Grand National four-barrel 354-inchers. In the original context we will be speaking entirely of very high horsepower "off-road" engines intended strictly for competition but the perceptive reader will find sound engineering principles which may be applied to any high performance internal combustion engine, regardless of make.
...
COOLANT CIRCULATION
Our dynamometer setup isn't as elaborate as some but we have found some definite cooling problems inside the case. Our tests show a temperature variation from one cylinder to the next. It might be as bad as 150° F from a good one to a bad one. We have tried as best we can to isolate this temperature problem from those of intake mixture distribution variations and exhaust pipe contour variations which will also cause cylinder-to-cylinder heat problems. It appears to be a built-in characteristic of the block construction and water circulation pattern. There are some variations in the pattern but normally the cylinders toward the front of the block operate cooler and those toward the rear hotter. As the water moves toward the rear of the block it becomes warmer. Consequently it does a less efficient job of cooling the rear cylinders. The tendency is especially pronounced on the left cylinder bank. When the water moves rearward some is routed upward into the cylinder heads through the matching water supply holes in the block and head decks. This causes some disruption of the heat distribution in the inboard four cylinders.
Obviously, pumping all of the coolant into the front of the cylinder block through the water pump inlets contributes to this uneven heat dispersion. We have tried several different methods to eliminate this disparity. To date we haven't found anything that has proven totally satisfactory. The general approach is to restrict some of the water feed into the front of the block and/or to reroute some water externally to the rear of the case where it is fed into the side through the core holes or through drilled holes in the side of the block. The relative temperature of the combustion chambers has also been equalized somewhat by controlling flow from the block, into the heads, by restricting or blocking off some passages and drilling some new passages.
Last edited: