It would be fun to take the engine in my 46, with the Kaiser super sonic head, and run it on the engine dyno, then swap to a conventional Willys head. I'll put that on the bucket list for when I win the lottery.
It would be fun to take the engine in my 46, with the Kaiser super sonic head, and run it on the engine dyno, then swap to a conventional Willys head. I'll put that on the bucket list for when I win the lottery.
Dyno info would be great but pictures of the heads side by side would be good too. Not a lot of easy to grab information on the engines outside of forum rumors. I saw somewhere the Supersonic engine was good for 7.3:1 or 7.5:1 compression but I haven’t been able to find it again. Wikipedia shows the Go Devil as being 6.48:1 but my maintenance manual lists 7:1. Maybe the year makes a difference. I don’t think compression by itself is enough for the boost in HP but combined with one or two other mods it may. The heads and other parts are said to be interchangeable between the engines (Wikipedia). One forum participant said Sears also sold the Supersonic as a replacement engine for the Jeeps so, in addition to the possibility this engine and/or head was swapped with parts from a Kaiser car, we also have the possibility it came from Sears as a replacement for the original Jeep engine.
I have seen an All State replacement engine once. It was in a Hobart welder.
I don't have real good pictures of the Super Sonic head on my 46, and could not find a clear picture on line. The third picture was the best I could come up with. The last two pictures are of a standard Willys head. There should be some pictures out there somewhere of both heads side by side. I'll keep on the lookout.
Last edited by gmwillys; 01-22-2018 at 03:23 PM.
I haven’t been able to find any more on the engines. Not even references to the different heads LarrBeard mentioned. It stands to reason the Supersonic engine just used a shaved down Go Devil head. I may have to go to the library on the next rainy day and do some “old school” research.
Check that they rate HP at the same RPM and at what torque...
In a Henry J, the rear axle ratios would have been a lot different that in the CJ's so that gave a bit of room on specsmanship. After all - 1n 1950 or so, you would expect your family car to have a lot more horsepower that that old Jeep you drove through Belgium!
Did the early Go Devils have less power? I keep coming across a 6.48:1 compression ratio reference. The jeep service manual I have claims 7:1. The Henry J references I have seen all say it is the same engine as used in the CJ3A with minor changes so parts were interchangable. I haven’t found anything stating the rpm used to get 68 hp. If they compared engines with the above compression ratios there would have been more hp but I don’t think 5 hp, let alone 8.
Initial power output for the Go Devil was 60 hp at 4000 rpm and 105 lb⋅ft of torque at 2000 rpm with 6.48:1 compression. The 7:1 ratio was for high altitude models, meaning that the horsepower would have been the same at 10,000 elevation, as it was at sea level. That's why you don't see horse power ratings with the Super Sonic heads installed.
The following link has a lot of information on the Go Devil. Some of your questions are answered within.
http://www.fourwheeler.com/features/...-encyclopedia/
Last edited by gmwillys; 01-24-2018 at 06:12 AM.
That’s a good link, thanks for posting it. It contains more information than I had come up with across a dozen websites in just one article. It’s no wonder there are varying hp claims. According to this article they are all true at 4000 rpm.
The hp rating is made at 4000 rpm. I can’t imagine spinning one of these engines that fast very often. The difference at lower rpm would be less and could become nonexistent when combined with other variables.
It would have been nice if Willys or Kaiser had published some information about different heads available. I just had another look at the maintenance manual and so far all I see is a 7:1 compression ratio listed. My parts manual lists 2 part numbers. The first one listed is for the 6.48 head. The second one has a part number lower in sequence and says “(up to engine serial no......)” which leads me to believe it was an earlier head. My parts manual is from Willys-Overland. My service manual is from Kaiser. I wonder if a Kaiser parts manual may have more information.
Last edited by 51 CJ3; 01-24-2018 at 10:02 AM. Reason: Correcting manual sources
Take the two manuals and bounce the information against the military M38 Technical manual. This should be the most complete information in regards to the latter Go Devil engine.
https://archive.org/stream/Technical...e/n81/mode/2up
https://archive.org/details/Technica...inBodyAndFrame