Gone supersonic

[garage gnome]

I finally got around to putting on the supersonic head I got from a member on my '53. There is a noticeable change in the idle. I haven't driven it yet. The combustion chambers look the same, but the stock head is deeper than the supersonic head. I took before and after videos. I can't notice anything different in the videos though.

Supersonic on top, stock on the bottom. Now I should feel the power when I step on it.  

[49willyz]

Supersonic head? This is why I love this forum. I'm learning something new everyday! Bet I'll be researching that one. Keep us posted on any noticeable performance increases. Not that we're turning much for horse power but I'm curious what that head with an overdrive would be capable of as well as crawling torque.

[garage gnome]

They came on the DJ3As. (looks at F Bill)

I don't think I'll be doing any crawling anytime soon with this jeep. Its too purty.

[F Bill]

They came on the DJ3As. (looks at F Bill)

Never heard that before, I thought they were installed on Kaiser cars......Of course none of mine have a SS head. I only have one that I THINK has the original engine in it.

[garage gnome]

Maybe I am wrong. I thought they came on the DJs since they have a higher compression ratio than a stock 3A.

[F Bill]

Maybe I am wrong. I thought they came on the DJs since they have a higher compression ratio than a stock 3A.

Another factoid I wasn't aware of.. When I get back from North Dakota remind me to check my DJ3A parts books to find out just which head part number they used..I do know the DJ3A had a reputation of being a rocket ship compared to teh other flattys of the time, but I always attributed that to the lighter weight and different intake and axle ratio.

I will bring this up over on teh Dispatcher board and see if we can get a quicker answer... 8-)

[Jesse]

My entire engine is a supersonic, although I don't really notice much rocket-ship like power. The body is made out of depleted uranium though so that probably does more than cancel out the bonus power on offer.

Supersonic sounds better than 60 hp from a marketing standpoint.


-Jesse

[Bob W]

The 1956 DJ3A parts list shows "640161 Head , cylinder (6.48 to 1 ratio)". That's the same head as a CJ-2A and a CJ-3A.

[calvinhunt]

Oh, come on Bob W., I was having so much fun following this thread.  If you mess our minds over with facts it spoils all the imagination.  

Seriously, however, we do appreciate that info, facts, bulletins, etc., are all available here on the 3A page.    

[Gunslinger]

I had a chat with Louis Larson one day, he had a SS head that he wanted to sell.  I think he told me that the top end performance was a bit better with the L134 with an SS head, but the low RPM tourque dropped off.  I translated that to be if you want to go faster in the higher RPM range great, but if you need to go slow up a hill, maybe not so.

I'm curious to hear how you come out with yours, some real life experience will help a lot.
Todd

[duffer]

First the disclaimer:  I don't actually claim to know anything--

But, seems to me a bump in compression should increase power across the entire rpm range if nothing is altered in the valve timing, especially at the compression levels we are talking here.  It is true that in higher performance engines (going to say cr's > 10), you don't gain much if using a stock cam and most (but definately not all) aftermarket cams will not have as good low rpm performance as the stock.  I don't think that is applicable here.  I do know shaving 0.060 off an F head made a difference felt at both ends of the rpms, just like bolting on the high compression head made for those.

It would be very interesting to see some before and after chassie dynamometer results.

[garage gnome]

I noticed a tiny bit more power down low. I didn't want to take it down any high speed roads because of the salt and crap. But it seemed better cruising down my dirt road.