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l20B upgrades


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Hello, I am new to this forum and I have a 510 with an l20B engine in it, which I am looking to get a little more out of, I have tried to do my research and I have came up with 3 things for some better street performance, a87 peanut head, bigger cam, dual carbs. these sound right? will the head bolt directly to my block and can i use my original pistons? also which cam and carbs do you guys recommend ? any and all help is appreciated. thanks.


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The unmodified peanut head A87 is only equal to the open chamber L20B heads as far as valves go, and the intake port size is smaller. As far a breathing goes the U67 would be better for the L20B. As to compression, a one point increase will improve efficiency maybe 3-6%. The stock L20B compression is 8.4 and closed chamber heads bump it to only 8.9 or 1/2 point. That's 1/2 of 3-6% but for argument sake lets say you get 3% increase. The L20B makes about 94 hp on a good day so maybe 3 extra horse power at it's peak of 5,800 RPMs. You won't even feel this. Keep in mind that higher compression makes your engine more efficient at capturing energy otherwise wasted. This is a racing 'thing' where any expense or bother is used to gain even the smallest advantage over someone else. Even 3 or 4 HP! In addition, a raised compression is also paired with other improvements like porting and polishing, larger cam, larger valves, bigger carbs, header, better ignition and so on. Not all these things alone will make your engine a 'race' engine. Lots of little things add up for a win.


What head is on your L20B? U67 or W58?





'Bigger' cam. Yes the more an engine can breath (in and out) the more power it can make. Here use caution. At high RPMs things happen so fast that the valves opening and closing times are radically changed to take advantage of this. Maximum power can be 6,500 to 8,500 RPMs and on a race car these RPMs are never below that and it works just fine. On a street car you need good starting and good idling qualities for around town and stop and go and seldom need to rev over 5K. It's true that it's better to want a larger cam that to have a larger cam and wish it were smaller. A too big cam is very hard to live with unless floored and out on the highway all the time.


Dual carbs are good when paired with a slightly 'hotter' cam. (breathe in) Again better to have too small a carb that too large and wish they were smaller. Just sayin'. A lower restriction muffler will also help. (breath out)


Yes an A87 head will fit and your pistons will clear just fine. 




Couple of other ideas...


Best performance bang for the buck? A 4.11 or 4.375 differential gear. Engine is revving higher in any gear at the same speed. Higher revs means it's making more power and torque at the same speed as before. 411 gears will push you back in the seat more than your 3.90s.  Mileage will be less but so will changing the cam. Absolutely no changes to the engine, will run the same. Speedometer will read higher that you are actually going but this can be fixed.


A single 32/26 weber carb. Nice performance increase for under $300 and a new carb.

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I am in the business of building and modifying custom cars and trucks and the first question I ask my customers is "how much do you expect on spending?" It's not that I'm trying to squeeze them for every penny, it's that I'm trying to gauge their expectations.


If you seriously want to run dual carbs, and have them set up properly to run to their full potential, you aren't talking about hundreds of dollars, you're into the thousands.


So how much DO you expect to spend?

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His 1st anwser is Im in School so dont have much money.


How much you want to spend.


If on budget I say do a bolt on 38/38 weber DGEV done in a couple hours



Is this your only car? If it is your car will be DOWN for a time. Best to have a daily driver and this be a hobby car on the side. If not this isnt really going to work. Most of the hardcore Datsun guys have multiple cars. If your only car keep it stock what you have

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