Pyro

if you want full boost at 3000 then use a stock T3 turbine. A good compressor to use for the L28 is a T04E-50 trim. You will need a 1/2 inch turbine spacer to add exhaust manifold clearance for the compressor. A stock turbo cam will not make power to 6500 rpms. They pretty much quit making power between 5,000 and 5,500 rpm. A non-turbo cam will extend the power out another 500 rpm. And the MSA stage 1 turbo cam will make power to 6,000 or 6500 but may have a little too much overlap for a stock turbine, but the down pipe may get you enough flow to run that cam. what sort of efi software are you talking about? what efi system do you have now? A stock rebuilt is a good idea. should cost about 1000.00 with new pistons. You most likely will not need new valves. Just get a valve job. stock turbo spark plugs are good enough no need for msd ignition, but you do need an efi system with ignition timing control and a coil pack (6 positions) A msd 2225 fuel pump is a good pump for your application. cheap. durable, and flows enough for 500hp. get a aeromotive fuel pressure regulator with a 1:1 reference. You could use the stock wastegate with a boost controller. much simpler install. You will also need a 240mm flywheel, clutch, and pressure plate to hold the torque. could make around 280hp with the stock turbo cam and 15 psi, 290 with the na cam, and 300 with the msa stage 1 turbo cam. you will need an IC to run over 10 psi of boost. A street car needs torque at low rpms and lots of it. A stock exhaust turbine, small cam, and 15 psi of boost makes a fun street car. You have the right idea. Don't use a stage 3 exhaust turbine, it make the car feel lazy at low rpms and will not make full boost until 3500 rpms. Not good for the street (if you want low rpm torque) use low impedance injectors between 370 and 450cc. It's very important to use low impedance injectors for a turbo application. And make sure the efi system is able to run low impedance. good luck

efi doesn't work so well with big lopey cams (no vacuum for the manifold sensor). It takes some special tuning to get it to work. You will have better results with some carbs. And even better results with a turbo. 10:1 cr is easy to get. stock flat tops and a N42 or N47 head is all you need. Then get a msa stage 4 cam kit, 6 into 1 header, later model 5 spd, and a 3.90 or 4.11 gear. Get a good set of su's or dual webers and it should run high 13's on the motor and maybe high 12's with a 75hp shot of n02. Get some new tires and lighten up the car. You can get a cam a lot cheaper than 600.00. Send your old cam and rockers to deltacams for a regrind (110.00), get a set of 0.200 lash pads from courtesy nissan (36.00) and a set of HP valve springs and retainers (msa, 120.00??)

FMU's work with the stock efi system. It enriches the fuel mixture by rising fuel pressure during boost. It is a very simple solution and works OK to about 7 or 8 psi of boost. I have mine working up to 14 psi but I don't recommend it. Much better to use megasquirt or something like that. Also, ignition timing control is very important for an efi system (don't get one without it). Don't use an old harness. That wire is 30 years old! Not a big deal to change it.

compression should be around....10.6:1 516cc /cylinder 44.6cc for N47 12.7cc for 2mm head gasket -3.7cc for +0.6 deck height (516 + 44.6 +12.7 - 3.7)/(44.6 + 12.7 - 3.7) = 569.6/53.6= 10.6:1

Looks like you need to run the racer brown cam due to high compression. What is the bore, stroke, head cc, and piston deck height? 10 to 10.5 is a pretty big range. You should be able to do a little math and get a closer estimate. Around 20 years ago, I ran a 240 degree Clifford Research cam in a daily driven 240z with a L28 block and 3.90 gear. I loved it! Came on really strong around 4000 rpm and pulled hard to 7000. It was a very fast street car, for the time period (new vettes only ran mid 14's in the mid 80's). However, I wouldn't do that again as a daily driver. Being older and wiser, I went with a quiet turbo setup.

That racer brown cam is more equal to the MSA stage 4 cam (290/290 degrees duration and 0.495"). The racer brown cam (242/242 @ 0.050") should run well with 10.0 to 10.5:1 cr The MSA stage 3 (270/280 @ 0.050") cam should run well with 9.5 to 10:1 cr What compression ratio does your engine have?

T04E -50 trim compressor seems to be the best fit for a L28. You will need a 1/2" spacer on the stock exhaust manifold for the compressor to clear the exhaust manifold. A T3 turbine works well with a L28. Plus if you use a T3 turbine, then you can use the stock wastegate and down pipe (if you are on a budget). Leave the turbine stock if you use the stock cam. If you use a MSA stage 1 turbo cam, then get the turbine modified to a stage 2 or 3. A stage 3 will hit full boost by 3500. With higher compression, a longer duration cam (like the msa stage 1 turbo cam) will help prevent detonation.

The easiest way to add a turbo would be to install the following: turbo exhaust manifold stock turbo, wastegate, and down pipe oil feed line and oil tee at oil sender oil pan and drain line from turbo engine stock J-pipe bell engineering FMU for fuel enrichment (225.00 new). This allows you to use the stock efi system. other things to do: lock out the mechanical distributor advance by filling advance slots with rtv. set timing to 20 degrees set fmu to increase fuel pressure to 60 psi at 7 psi of boost. relocate the pcv valve or put in a 90 degree fitting Should make around 185hp without an ic and 200 to 210 with a good ic. That is enough to run a mid 14 second run at 96 mph with 185hp or a 14 flat at 100 mph with the IC. you could do the whole job for 300.00 using used turbo parts and a new fmu. However, a megasquirt system would make it much nicer.

A v8 conversion is a lot of work. There are tons of little things that will nickel and dime you to death. Plus the fabrication skills and tools needed to make it a "good daily driver" is hard to come by. I have done a few V8 conversions and a few turbo conversions. And adding a turbo to a L28 is much much easier, makes about the same power, and cost much less time and money. So yes, I trying to talk you out of it. add megasquirt II to your engine, then add a msa stage 1 turbo cam and a t04e-50 turbo.

Not sure what your question is but.... The wastegate just bypasses the exhaust turbine. The 1 inch hole is before the exhaust turbine so the external wastegate just diverts the exhaust flow around the turbine (just like the stock wastegate does). or The bypass valve connects the suction side of the turbo to the throttle body input. so when the throttle blade closes the air has some where to go (back to the turbo intake). The output from the turbo goes under the oil pan (the turbo is clocked downwards) so you can't really see the turbo out put tube.

I was running high 10's at 135 but it was breaking stock axles every 3 or 4 runs. So, I was working on it more than I was driving it. Even when it ran high 11's at 120 (no n20) it was breaking stock rear drive line parts more often than I would like. Sure you can go fast in V8 Z, but using stock rear drive lines can be short lived and dangerous at high power levels.

Ah, go back and read the second post! It isn't that hard or expensive to machine in bigger spring cups. I'm guessing 100.00 should do it, if you disassemble and reassemble yourself. You really should measure your "actual" installed height. This can vary from head to head by a lot. And especially if you re-machine the spring cups. 132 on the seat and 293 at 0.050" seems a little high for a flat tappet. I feel compcam tends to use too much spring pressure. 110 to 120 on the seat and 275 at 0.500" should be enough.

Keep the dampener in place. So use the outer spring and dampener. Do you know what spring pressure you are using? seat and at 0.500" lift?

mr six, yes, you are right. I was most likely smoking crack that day with I looked up threshold. Threshold is the rpms when the engine starts making boost.

Should be ok sitting there for a few months. Make sure to use EOS oil additive during the cam break in. And I would use a little EOS at each oil change. I would also consider using just the outer springs for the cam break in. I know it is a main pain to swap springs on an engine but worth it if it saves the cam lobes.

Make sure to use low impedance injectors. These injectors can run much better precision at low duty cycles than high impedance injectors. Low impedance injectors are especially useful on turbo engines that require an extra wide range of fuel delivery (idle to full boost). Yes, you want to run ignition timing control too. Makes a huge difference in throttle response, gas mileage, and engine life (especially with boost).

I don't think so. After recently researching "turbo terms" on the web, Lag is a no boost condition and Boost Threshold is when the turbo makes boost but the engine doesn't use it. I guess this would happen if the engine doesn't have enough rpms to be in the power band of the cam.

I mean lag. High flow turbines don't boost as low in the rpms as restrictive turbines do. I do think my engine does have a little boost threshold problem. Boost does start to come on at 3000 but the engine doesn't seem to use it until 3500. Most likely due to the cam (msa stage 1, 260/250 114 lsa) and maybe less than ideal ignition timing (28 degrees total). However, the stock setup was the same way, boost would come on as early as 2200 in 4th gear but the engine wouldn't use it until around 2800. Again, could be an ignition timing issue. It would be nice to get an efi system with ignition timing control so I could test that theory. Yes, I don't like using "stages" either for describing turbines or cams or anything else. But I forget the A/R on the turbine, but do remember stage 3. Got it from majestic turbo in dallas. I bet they would know how they set up their stage 3 turbines. It is a different wheel and a machined turbine housing. I do know full boost comes on about 700 rpms later than a stock turbine. And I can drive down the freeway at 80 mph with 10inhg of manifold pressure with the stage 3. My stock turbine was at 0 inhg at 80mph (almost boosting). I use a 3.90 gear and a later model NA 5 spd.

here are a few nice sites http://www.turbobygarrett.com/turbobygarrett/tech_center/acronyms.html http://www.squirrelpf.com/turbocalc/

What are your intensions for the car? Typically a T04E 50 trim compressor for the L28 is a good choice. Can boost at low rpms without surge and still can handle and good amount of rpms, high boost, and up to 450hp. Use a stock T3 turbine if you plan on using the stock turbo cam. If you plan on a longer duration cam, then have the turbo shop open up the stock T3 turbine for more flow (stage 1, 2, 3, 4, 5,) The better the turbine flows, the more lag the turbo will have. However, this is ok and required if the cam is bigger than stock. And, the bigger the cam, the more open the turbine should be. longer duration cams will have more overlap. This makes the engine not like high exhaust manifold pressures. Because, when the exhaust manifold pressure gets higher than the intake manifold pressure and if both valves are open at the same time (exhaust and intake valve overlap), the exhaust pressure will push out the intake. This is avoided with free flowing turbines because exhaust pressures are kept relatively low. When using a stock turbine, boost is very quick, but exhaust manifold pressure is very high. However, this isn't a problem with a stock cam since there is no overlap. The down side is power falls off at 5500 rpm. The up side is gobs of torque at 2800 rpms, which is fun on a street car.

8.3 or 8.5, doesn't really matter than much. But yes, the off boost power will be better with 8.4 as compared to 7.4:1 cr. Don't think it would be possible to run 87 octane with 8.3:1 cr and a turbo You will need to lock out the stock distributor (silicon up the advance slots) and set timing to 20 degrees. Continue using the vacuum advance and make sure it works, if not mpg will really suck. And use a Bell Engineering FMU to increase the fuel pressure to 55 or 60 psi during 7 psi of boost. Should make a mid 14 second car at 96 mph and a low 14's at 100 with an IC. Can try more timing for more power, but 25 degree will be about the max. I also recommend tightening up the afm flap 7 or 8 teeth.

Yes, the P79 flows like a P90. Yes, you can run it with the crack if the shop had pressure tested it and it didn't leak. I have a crack on my turbo head just like that and run 14 psi of boost for the last 4 or 5 years. A friend on mine made a turbo engine with the P79. Ran ok, seems to be a little more prone to detonate than my P90 set up. He had to run a little less timing than I did. But that is just one case so I'm not sure if the head was the problem. You can make a nice turbo setup with the n42 block and N42 head. Just can't run as much boost when using the stock cam and turbo. It will run fine at 8 psi of boost. You would need to limit timing to 20 to 24 degrees with 8.3:1 cr (stock 75 to 80 cr). However, if you run a msa stage 1 or 2 turbo cam and a bigger turbo with a free flowing exhaust turbine, then you could run maybe 12 or 14 psi of boost on pump gas with 8.3:1 cr. if you use a P79 head, make sure to use the head gasket that matche the block. If you use a F54 (81 to 83) head gasket on a N42 block (75 to 80), it will over heat.

All the numbers that I have been giving you are based on my 240 V8. started out with a 3.90 gear, T5, compcam 292H, 362 sbc, 10.75:1 cr, heavily workout over double hump heads, block huggers, 2-1/4 duals to 2-1/2 single exhaust, performer rpm, holley 750 3310 vacuum secondarys. ran 12.7-12.9's at 110-112 on small street tires (215/60/14). Then ran some mid 12's at 114 with some better traction tires (bias ply MT) and true duals (cut passenger side off gas tank to make room for another muffler) then added same better heads (200 cc dart iron eagle) and some full length headers and some MT drag slicks (26 x 8 -15). and ran some 11.7's at 120. Broke axles every 20 runs then added a 200 shot n20 and ran 10.7's at 135. broke axles every 3rd or 4th run. Yes, the performer will pull to over 7K rpm. My engine would valve float at 7200 (according to my 5 inch autometer tach). However, my best et's came with 6500 rpm shifts even though the engine felted like it was pulling hard to 7,000. I'm not sure a 282s with rev to 7000 in a 327. You may need more cam compcam makes a XS274s than has duration of 236/242 or have you considered the new 30-30 compcam (12-673-4) 284/291, 247/254, power from 2300-6900. Block huggers are not good headers. Yes, they are much better than manifolds but not nearly as good as full length. But, full length headers are hard to get into a Z. And it is tough to get a good exhaust system under a Z. Furthermore, most all GM heads have poor e/i flow ratio (under 75%). Every performance chevy magazine would say that an engine with a poor exhaust system or a poor e/i ratio will run better with more exhaust duration than intake. Easy to research that. Also, the general run for manual or vacuum secondarys is, auto trans cars do better with mechanical secondarys and manual trans cars do better with vacuum secondarys. The reason is, there is more secondary tolerance with a torque converter than a clutch that locks up. Plus, if you want any gas mileage at all, get vacuum secondarys. I wish I would had left the car in the 12 second configuration (the way was when I first built it). It got too crazy to drive on the street and lost its street car appeal. And it sounded much better with single exhaust.

I would use a performer rpm intake. Not an air gap. An air gap takes a lot time to warm up the carb so in the winter it is a pain to drive. Plus nuts and bolts are always falling into the carb which sucks. I would use a 3.90 gear. Especially with a 327 which will be low on torque compared to a 350. The 282S is a nice cam but you may want to consider a cam with a little more duration on the exhaust side to compensate for poor flowing gm heads and block hugger headers. I think compcam makes a grind in between the 282s and the 294s that is a dual pattern. A 750 3310 holley with vacuum secondarys would work fine. Get some 68, 69, and 70 jets for carb tuning. And maybe a 34, 37, and 40 squirter. A GM T5 5 speed would also be a good choice. A crane HEi for ignition (summit racing) get one with vacuum advance. As for exhaust, I would recommend 2-1/4 off the headers to pair of dynomax bullets then to a Y-pipe then to a single 3 inch pipe then a hooker aerochamber on the end. I recently built a similar exhaust system and it sucked without the bullets. Had to go back and put them in. Should be able to get your 240 into the high 12's at 110 mph with that setup. Would be a fun street car, no doubt. A better set of heads, full length headers, and a little more cam should get you into the high 11's at 118 or so.

I get 10.12:1 with your specs. 333cid= 682cc/cylinder 0.016" in the hole and 4.030 bore = 3.3cc -1cc for dome 8.4cc for 0.039" head gasket (682cc + 3.3 -1 + 8.4 + 64)/(3.3 -1 + 8.4 + 64) = (682+74.7)/74.7 = 10.12 With roller rockers you need the longer studs than stock (+0.250"). if you plan to use 1.450" diameter springs, the heads will need to be machined. What are your plans for gear ratio, transmission, exhaust, intake, carb, and ignition?