Horsepower by Hauser
Modifications to the Datsun 1600 3 and 5 bearing engine by Joe Hauser, National SCCA Champion - G Production
A fascinating insight in Joe's
own words into the modifications to his championship winning Datsun 1600
engines. My thanks indeed to Joe for his efforts and enthusiasm for this
The following are details of a few of the changes/modifications that I made to the Roadster over the years that made it not only faster but also more reliable.
Ill start with the Engine as it was the most interesting and difficult to modify and have it put out a lot of power and to make it live at high RPMs. All of the following refer only to the 1600 engine and Ill specify whether the reference is to the 3 or to the 5 main engines. The bore stroke ratio of the 1600 is considerably over square ie 3.433 bore and 2.66 stroke and since the Sprite was the reverse ie long stroke small bore, I bought a how to build a small block Chevy engine book and used much of that info to do the 1600 Datsun. You might ask why I did not use the Bob Sharp book on preparing the engine. I did to a certain extent but by the time I started building the 1600 a lot of the Sharp info was out of date, and technical knowledge improved so much that different approaches were needed. The major differences were in pistons, cams, and crankshaft modifications, so that the extra power and rpm would make the engine survive a series of races and not make it a hand grenade.
The 1600 engine had a very sturdy bottom end in terms of strength especially the 5 main engine. However that made it a good street engine but not so good as a race engine. For example we found that the bearings in the 3 main would last up to about 7200 RPM, while the 5 main was no good over about 6700 RPM. So what to do? Something had to be done to the rod bearing oiling system. A friend named Ron Frazer and I got our heads together and decided to do something after he had rod bearing failures on two engines he was running on the dynamometer. We couldnt agree on the way to solve the problem. So we decided that each would do it his way. Both worked. Ron only ran 5 main engines so his way worked OK I ran both 5 main and 3 main engines and found that the 3 main was a little lighter and just as, if not more reliable than the 5 main. To keep from throwing rod bearings, (burning them out), I redrilled the crankshaft, both the rods and the mains.
CLICK HERE FOR A DETAILED EXPLANATION OF JOE'S CRANK MODIFICATIONS
The mains I just cross drilled, but for the rods I had to drill two holes, one on each side of the crank pin to intercept the original drilling. I then plugged the original hole outside where the new holes intercepted the old hole. This method completely cured the rod problems and rod and main bearings would last a whole season. The stock connecting rods were pretty sturdy but after having one break I made it a habit to change them about every other season.
(Ron Frazer drilled his 5 main cranks similar to the cranks on the 2000 ie drilled from the # 2 main to feed the # 2 rod and from the # 4 main to feed the # 3 rod. I don't think he did anything to the # 1 or the # 4 rod journals since the rod burning problem was generally the # 3 rod ,although sometimes the # 2 rod would go. He also cross drilled all the mains).
One other thing about the bottom end was that the Datsun machining was outstanding. All the bearing surfaces were the same in all the engines that I disassembled. That meant that all the crank surfaces were sized for street use so all the crank surfaces had to be ground one thousandth of an inch in order to have adequate racing clearances. (Rods .002, mains .003). Because the 1600 has large bores and only three cam bearings the cam became a problem, especially when reground for the high lift and the high revolutions that we had to run to get the power we needed to run competitively. The first couple of years I ran with reground stock cams but after losing the runoffs in 1979 because of a broken cam I found a couple of steel cams that the Electromotive crew had made and that basically solved the cam breaking problem. But as with all high preformance high speed engines one always has to watch the lifter and cam lobe wear. This meant checking lift and clearances after every race and sometimes even after a qualifying session. If the clearances and leakdown was off.
I dont know how many engines that I built in the 21+ years that I ran the Roadster but my guess is 7 or 8 from scratch. SCCA rules allowed a 47 thousands overbore but all the new engines I built were bored 40 thousands over and new pistons were installed. I used 40 thousands to allow for wear and possible piston substitution if one broke and the bores had to be honed for the replacement piston. Pistons were purchased from Venolia, Cosworth and Aries. In order to get the compression ratio up to the 12.8 to 13.5 ratio needed the pistons always had to be tailored to fit the combustion chambers and the valve clearance requirements. After I built the first engine and ran back and forth to the machinist I went out and bought myself a vertical milling machine so that I could do the pistons and most of the head manicuring myself. I did all the head porting and polishing myself learning as I went along. I got a lot of good info from the book on preparing a small block Chevy engine. I fact the first cam I ran I went to the cam grinder and asked him for a good small block Chevy cam. We went through his cam masters and settled on a cam he called a BL3, so we ground the cam to those specifications. This cam setup won the first Runoff for me (1976) (and a lot of other races) before we came up with a better one. Incidentally we, Lois and I, did quite a bit of dyno work in getting and keeping the Roadster competitive. Our local machine shop has a computer controlled dyno and after checking us out he allowed us to do our own dynruns and only charged us a very reasonable fee. Over the years we must have checked at least a dozen different cam variations and ended up with one the cam grinder calls a 250/350/102, which indicates the duration, lift and lobe centers. (Lois is my wife and was my right arm both at the track and in the dyno room).
Turning to oil pressure, I generally set this at 60 psi. I never had any oil pressure problems. I used an Accusump and faithfully pre-oiled the engine prior to starting it after it had set for any length of time.
The other item of importance to power out put is the head, and creating the least impedance to air in and exhaust out is of great importance to power output. Proper porting, bigger valves, heavier valve springs and carburetor modifications were some of the things that needed to be done. A lot of this was done by the cut and try method especially since I didnt have a flow bench. I guess I did at least a dozen heads over the years and by the time I quit we had improved the power output from a nominal 90 horsepower in street form to about 157 horsepower at 7800 rpm in racing form. The first engine that I won with in 1976 probably on put out about 135-140 horsepower at about 6700 rpm. That is a guess since I did not have a chance to dyno it.
To condense the above to make the 1600 competitive one must: modify the crankshaft to, increase bearing clearance, redrill crank to improve the oil distribution, bore the block for new pistons, fit the pistons to the head, mill the head to fit the pistons, grind a new profile on the cam and modify the carburetors for improved air flow. To do all this takes a lot of time because the parts must fit properly and clearances must be exact. I did not keep track of the hours involved in setting up a race engine but I estimate somewhere between 150 and 200 hours of detailed work was involved.
Col. Joe Hauser
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