Stock Hp On A 1973 Gtv2000 Plus Upgrades

Back when I used to work in the computer hardware industry, we used to say that the standard measure of computer performance, called "MIPS", stood for "meaningless indicator of performance". Perhaps someone can come up with a similar acronym for "HP".

Sure, more hp means a faster car. But, it ain't as simple as that! You need to look at where in the rpm range the car makes that 120 or 150 hp. For Alfas, this is typically at 5,000 rpm plus - useful for a competition car, but less useful for the street. You also need to look at where your engine produces its maximum torque, and make sure that this is in the range where you can use it.

Enthusiasts can do things that are counter-productive by just bolting speed equipment onto an engine, and expecting big results - while this may increase the maximum hp, it may also shift the point where max. torque is produced up the rpm curve. In other words, the engine may end up being weaker in the speed range where you most typically operate it.

I'm not trying to talk GTV6PASSION out of installing "Heads shaved an additional 40 thousands off, bigger valves, 10.5mm cams, higher compression Pistons, 4 to 1 Headers, and a Free Flow exhaust" - I'm just suggesting that this stuff takes some planning to make it all work optimally, and to ensure that it produces results consistent with how you will be using the car. One thing not on this list is dyno time - you will probably achieve better results by installing mods incrementally, and optimizing the results on the dyno, than by just bolting on expensive speed equipment.

So, I don't want to come across as some know-it-all, or like I'm throwing cold water on GTV6PASSION's passion. I'll admit that I've made every rookie mistake in the book, like bolting on speed equipment, and expecting my 2 liter Alfa to feel like a 5 liter Corvette. My advice would be to find a grizzled old dyno operator in your neighborhood, and have them advise you on how to modify your Alfa engine.

I went down this same road with my datsun. While not an Alfa engine, I thought I was playing with about the same #s. I started with a set of headers, 44mm Mikuni carbs with 37mm venturis, and the factory "B" cam to bring it to non-US import spec claimed 150Hp. While this a is the factory claim from Nissan, the truth is more like showing 100-110 hp at the wheels. Many roadster owners have dyno'ed in this range, so beyond 110 hp out of the Nissan U20 2L engine is rare. I then went for a bigger cam, both in duration and lift. It made a small difference, but not much. I then bored the engine .060 over and added a knifed edged crank. The engine was rev happy as all get out, but I doubt it was making more than perhaps 115 hp at the wheels. Last year I went big, a full race ported head with a custom ground cam to go with it ($$$$) I was told a U20 could never and would never make anywhere near the HP of a modern Nissan SR20, they were wrong. As you can see the power curve and torque curve are really nice. The day I did this dyno pull, I was supposed to have a new exhaust system on, but the guy was a no show for work that day, so I ran it with the 2" pipe. After getting the new exhaust on, the car definetly makes more power than it did with the 2", especially at high RPM. Still 141 hp and 132# ft of torque at the wheels out of a 40 year old 8 valve 2L SOHC isn't bad. I know it makes more than this now, I just haven't had it back on the dyno.


Now after saying this, I think to get an Alfa engine to make this kind of Hp would take a huge amount of work. I don't know what a full race ported head flows, but the alfa nord engine isn't going to make power like my U20 and still be easily streetable. You will need high compression (on todays pump gas? Right.) I have been looking into building a monster Alfa 2L, and from what I have found is that 200 hp is attainable, however the compression ratio is on the moon, and the power curve is more like a spike, with both peak power and torque found at high rpm. I don't think this would be a fun engine. Now a turbo could be the answer here. If you can force more air/fuel into the combustion chamber, you will make more power, possibly at a lower rpm, and lower compression ratio. Neither rpm nor compression high compression ratios are really a good thing for a street engine. High compression leads to pinging, and rod bearings take a beating. Also head gaskets tend to take a beating as well. High rpm leads to more wear, potential for cracked pistons, piston liners moving around, and other unfun things like that. The pistons are not the most efficient, however apparently the Motronic ones aren't as bad. A flat top piston would transfer energy better as the explosion is directed downward rather than to the sides. The problem here is a lack of compression ratio, or valve clearance if the head is shaved down to bring the c.r. back up. One could do pockets in the pistons to clear the valves, but this will lower the c.r back down again.

I say do some homework, talk to the experts and see what you come up with. Yes you can get a fair amount of power out of a 2L Nord, however it will take lots of $ and some serious research. If you find a clever way to do this, let me know as I'm interested. (Yes I feel my 1750 is lacking in the power dept.)

just my $0.02,

Will