Pyro

You right, this is not the right site to discuss a N20 shot on a L28. However here are a few comments on your post. If you use the Datsun Cold Start Injector for the N20 fuel enrichment then you first need to know the flow rate of that injector. Pull it out and measure the gas flow over 30 seconds with the car running. That injector uses 12V activation. Then you can match the amount of N2O to that fuel flow. So, it all depends on the cold start injector flow rate on how much N20 you can add. But, who knows how well that injector distributes the fuel to all 6 cylinders? A mass air efi can handle a small dry shot of N20 (100hp) but not a datsun air flow meter. I have no idea if a datsun auto trans can handle N20. But i'm sure you can try it and find out. However, i'm sure the engine can handle a 100 shot of N20. But you will need to retard the timing about 5 degrees and add the right amount of fuel enrichment to the N20. Which means the fuel pump will need to pump a good amount of fuel. You should only add N20 above 3000 rpm and at full throttle. Buying a How to N20 book is a great first step!

I have a friend that sprayed a 200 shot on a cast crank/piston 350. He ate 20 to 30 lbs of N20 a week for over a year before the motor started to smoke. He raced at the track every friday night and on the street sunday night. The short block was just about an autoZone special but he used a 292 comp cam, 64 cc dart heads, headers, and a good intake. I'm not saying this is what you should do but it is an example of how much a stock SBC can handle. I'm sure you could build a mild streetable engine (9.5:1 cr) with a strong short block and spray a 400 to 500 hp shot of N20. I spray between 125 and 275 shot on a 2 bolt main 350 block with good rod bolts, forged pistons and crank. The engine also has about 11:1 cr. The most important thing is to have a high volume fuel system, good fuel, and timing retard. A mallory comp70 fuel pump and a one gallon fuel cell mounted by the radiator and full of 116 octane is a nice way to add fuel enrichment to a N20 system.

Sounds like your new engine will be a strong runner! However here are a few things to think about: The externally balanced 383 needs the bigger counter weighted balancer (8") which requires the engine to be set up higher by 1 inch. 1 inch doesn't sound like much but the air cleaner will not fit with the engine up. You could get the crank internally balanced then you could use the smaller non counter weighted balancer. FYI, the JTR V8 conversion uses a 6" balancer. Also, those canfeild heads will need longer than stock pushrods (+0.100" to +0.160"). Finally, I would install the cam straight up eventhrough comp puts 4 degrees in their cams. I run my 292 comp cam straight up and my Z runs very well. A friend of mine advanced his comp cam 292 by 4 degrees and dropped 0.5 sec in the 1/4 mile in his camaro.

Lets not forget how the information gets into the data bank. If the old question isn't asked anymore then no new information is obtained. I'm sure not everything about LS1 and LT1 conversions has been discussed. You never know, a new member with a lot of experience on the subject could ofter more information. But unless someone posts the question again then the newest information cannot be shared. If you have already put your answer/opinion in the data bank on that subject and don't want to answer the "old" question then simiply don't. And let someone else share there thoughts and experiences. Who knows, we all could learn something new.

I think Desktop Dyno over estimates HP most of the time. It is best to read stories in old chevy mags to get real hp numbers. I agree with grumpyvette. Vortec heads are the best bang for the buck. And I would also build a 350 over a 327 any day. The longer stroke makes a much better street engine with a wider torque curve. The cams you have choosen are on the edge of a smooth idle and a slightly rough idle. So good job there if you want to keep a good idle! If you do use the vortec heads, then get the cam that has more exhaust duration. Furthermore, I would avoid a solid cam if a loud valve train bothers you. I think you can build a 375 hp+ engine with 9.25:1 cr, 355cid, vortec heads, performer rpm air gap intake, holley 750 with vac secondaries, and a comp cam 265. And a little bowl work on those heads will get you another 25 hp. A 327 would make about the same HP as a 350 but the torque would be down at least 30 ft lb over the entire rpm range. I like your exhaust choice! I ran the same a few years back and really enjoyed the sound of a V8 running single 2.5 inch exhaust. Just make sure to get a smooth Y-pipe.

Wow. 400 ft lb at 2200 rpm at the wheels is 480 ft lbs at the crank! Looks like a 7 liter turbo diesel torque curve. Are you sure that dyno is reading right????

Before I did any fuel system upgrades on my V8 Z, I got by with the stock 240 fuel lines (5/16"). At that time, I was using a mallory 110 pump and a 750 Holley carb. I was running low 12's at 115 (400 hp) with that setup. Then I installed a 3/8 feed line welded into the factory tank and a better set of heads and exhaust and ran mid 11's at 120 mph. Then I installed a 1 gallon fuel cell by the radiator and used a comp 70 pump on a 175 shot of N20. I would use racing fuel in the 1 gallon fuel cell. My car ran mid 10's at over 130 mph with that setup. So if you are going to run N20 then two fuel pumps and two feed line might be a good idea. Now, I have a fuel cell with 1/2" feed and return lines, a return style fuel pressure regulator, and a Mallory 140 pump. When I first installed the bigger lines, I used a comp 250 pump but the pump made too much noise for my taste. However, I think the comp 140 is a little too small for 600 hp. But that comp 250 was LOUD! The size needed will also depend on what fuel pressure you use (carb or injected). You will get more flow through a fuel line at higher pressures. The comp 140 and comp 250 mallory both run at 14psi. A high pressure fuel injection pump will flow even more volume through the same size fuel line. So, I think 3/8 should do it but 1/2 will be safer. FYI, 1/2" lines were a pain to run. If I had to do it over again I would run two 3/8 lines. And, if you use a return line system then the return needs to be the same size or larger than the feed line.

I would think it would depend greatly on what compression and which cam your 3.1 liter engine ends up with. And of course, how well the efi or carb is tuned. With all things the same (cam, cr, exhaust, intake, etc) you can only expect about a 11% increase in HP and torque over a L28 engine or a 30% over a L24 liter engine. The 11% and 30% is the amount of increased displacement over the L28 and L24 engines. A 3.1 liter engine will have a higher compression ratio because of the larger piston volume and the same CC head as the l28, and therefore will pick up a little more power. A stock 81 to 83 L28 will make about 145 hp and 150 ft lb of torque so a 3.1 liter will do about 165 hp and 170 ft lb. If a bigger cam and more fuel is delivered then a 3.1 can make some big numbers as seen in the previous posts. A L24 would make about 200 hp and a L28 would make about 230 hp if both engines were setup like the 255 hp 3.1 liter that is shown on the dyno above.

As for my car, I didn't notice a change in mpg as long as a didn't step into the throttle too much. I'm running a +400 hp, 11:1 cr, comp cam 292, dart heads, full length headers, 2.5 in dual exhaust, 362 cid small block with a GM T5 and 3.90 gears in a 240Z. It is very important to make sure the jetting is right for your carb and it would help a little more if get the converter to lock up in OD. I also believe that MPG is more of a function of weight, drag, and gearing. However, not when is comes to big block chevys which always seem to suck 1/3 more gas than their 350 little brothers.

Canfields require longer push rods than stock to correct the valve/rocker arm goemetry. You need to use an adjustable length push rod to figure out which length you need. In most cases, a +0.100 or +0.160 push rod will work. This could be the reason why your engine is low on power.

I had the same problem and solid mounting the diff at both end solved the problem. Plus I moved the trans tail around in order to get the driveshaft as straight as possible.

You can't fill a torque converter with out special transmission equiment. However, you can and should only pour in 1 quart into the converter when it is new. The rest of the fuild is added to the converter by the transmisson pump. So, by adding fluid to the transmission pan, the trans pump will pump fluid into the converter. Depending on the diameter of the converter, it will hold about 5 to 7 quarts and the pan will hold 3 or 4 quarts. If the fluid level in the transmission pan was at the right level on the dip stick then the converter had all the fluid it needed. Furthermore, an automatic transmission 3 quarts down will hardly move. So I think you most likely had some other problem than low on fluid in the converter. One thing to be careful of is that stupid TV cable. The cable increases line pressure during acceleration and if it isn't adjusted right, it kills the transmission and converter. As for me, I will never own another 700R for as long as I live. I hope you have better luck than me. I finally installed a GM T5 and was much happier.

I'm not sure about the AFR's but I know the cantfelds will need +0.100 longer push rods which will cost another $100.00.

A power guide trans is good only if you use it in a car with at least a 3:1 hp/lb ratio. Turbo drag cars use them a lot but have 1000 hp in 2500 lb cars. It would be a very big mistake to install a power guide in a high performance street car.

Sounds like it could be an ignition timing issue. Check if the ignition advance is working correctly by using a timing light. Also, make sure your vacuum advance line is on the right carb port. On a chevy, you should use the port that has NO vacuum at idle. This is one of the most common mistakes people do with an old chevy. If you connect the vacuum to the wrong port on the carb the timing will retard instead of advance during acceleration. A ford works in the opposite manner and therefore needs vacuum to the distributor at idle. Then set your timing so you get 40 degrees maximum timing at 5000 rpm.

If you want to make HP on a budget you should rebuild a stock 350 and install a good set of heads, intake/carb, and a big street cam. A set of vortex heads on a 350 block with a 270 comp cam and a performaner rpm intake and Holley 750 will make 400 hp. A 350 with cast pistons, cast crank, 2 bolt mains, and stock rods will handle 400 hp without any problems. And rev just as well as a 283 or 302 if the cam is big and the valve springs are correct. I have been shifting my 350 at 7000 rpm for the last 10 years without any problems or a rebuild.

Go to chevyhiperformance.com. They list a BUNCH of flow numbers for chevy heads. The AFR heads have the best flow numbers. I'm using the dart heads on my z but I have been lusting over the AFR's.

Chevy vortex truck engines are a great deal. And they make great power. They do make vortex intake manifolds for carbs but I would try to get the stock vortex efi working. Then if you need more power, get a super charger kit for a vortex 350 and pick up 150 hp while keeping good drivability and reliability.

Make sure that the block huggers you use have 3/8" thick flanges. The Hooker Super Comp block huggers (PN 2100) have the 3/8" thick flange. FYI, you will lose HP with the block huggers as compared to full length headers. However, block huggers are much better than exhaust manifolds. I recently read a header dyno test result which showed the blocker hugger heads splitting the gap between full length headers and stock manifolds.

Chevy put 750 cfm carbs on most of their 4 barrel engines from 283 to 454 cid. Most quadrajet carbs are 750 cfms and some are even more. However, the carbs have vacuum secondaries. This allows the engine to only pull the secondaries open to the amount it needs. So, you might not use all 750 cfm's. When the secondaries start to open is tunable on a Holley by changing the vacuum spring. A lighter spring will allow the secondaries to open fast and fully, a heavy spring will require more rpms to open and will reduce the amount it opens. So, if you get a 750, it will give you room to grow. If you stay stock then use smaller jets and a heavier vacuum secondary spring. You can also change the size of the accelerator squirter and cam. springs, jets, and squirter are very easy to change and allows you to tune your carb to fit the car/engine combo. Holleys rock. They are easy to tune, parts are easy to find, and they last for years and years.

Sounds like an accelerator pump problem. I had one of those carbs a few years ago and the seal in the accelerator pump would always go bad. I finally threw that carb in the trash (major piece of junk!). It is made of the wrong material anyways. Alum. carbs heat soak and boil the gas in the fuel bowls. You should buy a Holley 750 with vacuum secondarys (Holley 3310). Then install leaner jets in the primaries because Holleys always come jettted rich. A set of 68's or 69's should be about right. Jets are very easy to change in a old style Holley.

Nice looking install!! I think your HP numbers are right on target. 281 hp and 320 ft lb will make your car move very well. From my calculations..... 281 hp and 320 ft lb at the wheels is 351 hp and 400 ft lb at the crank (20% loss in a chevy). Six psi of boost will give an engine 1.408 more HP. 1.408 = ((6 + 14.7)/14.7). Therefore your engine would make 250 hp and 285 ft lb without the blower which is about right for a mild cammed 350 with low compression. I think you wull need more boost to get the power up. 10 psi of boost will give 1.68 times more HP and torque (420 hp and 480 ft lb). A set of 195 cc AFR heads will also increase hp over stock ported heads. You might get 40 or 50 hp more. Do a search on the web for Sanderson headers. They make a set for the small block that look like Block Hugger Headers but the tubes continue along the block and turn at the oil pan to form full length headers that will fit a Z V8 conversion.

The 77 350 from a truck or a vette is your best bet (180 to 190 hp). A 77 350 from a passenger car will be a dog (150 hp but 300 ft lb torque). However, a set of 64 cc vortex heads, vortex performer rpm intake, 750 holley carb, and a cam will make 400 hp very quickly. I think you should install the low HP motor for now because there are a lot of things to do before you get the car driving (mounts, cross members, cooling, drive shaft, wiring, exhaust, shifter, etc). Then later upgrade the HP for about 1000.00 with the above mentioned items. However, use the hooker block hugger headers (PN 2100) with a single 3" exhaust on the low HP engine so you won't need to upgrade the exhaust later. Please get the JTR manual before you start your conversion. Another option would be to keep the low hp engine and spray some N20. I have seen junk yard motors make 500 hp with a 300 shot of N20!

A few years ago when I was using the factory radiator on my V8 240, my engine would run 245 sometimes but it never popped off a radiator hose. Maybe you have a bad head gasket which is adding pressure to your cooling system. When a cooling system is over pressurized it will release coolant through the radiator cap and then over heat. Just something else to consider.