Pyro

It would be cheaper to buy a complete engine and transmission from a later model gm. for less than $2000 you can get a low mile 5.3 liter from fan to tail housing complete with all brackets, pulleys, accessories, and efi . Then maybe another 2000 to get it running in and running (brackets, mounts, shifter, radiator, driveshaft, efi work, speedo, wiring, et)

I recently built an exhaust system like that for a friends V8 conversion. But after a test drive we found out the drone inside the cabin was so bad it made the car undriveable. So, I installed a few dynomax bullets and a H pipe before the y-pipe. After the exhaust modifications, the exhaust sound in the cabin is almost stock during slow to moderate driving. I bet the wife would like a quieter cab. Good job on the conversion.

Yes, my 280z weighs 2850 pounds (just like every stock 280z out there). That is the stock curb weight for a 280z or 280zx coupe. Stock 240z's weigh in around 2400. functional bumpers, bumper supports, heavier doors, AC, more electronic stuff, and heavier rear ends (r200) made 280z much heavier than 240s.

FYI, 2 types of glass pack designs out there. The old fashion one which uses raised bumps in the exhaust stream (louvered) which is very bad for flow. And the new design which uses a bunch of little holes in the tube ID (perforated tube). The new glass pack design flows almost like a straight pipe and the old design like a restrictive stock muffler. The dynomax bullet uses the new design.

a 280z weighs around 2850 lbs a 89 mustang around 3300 lbs. that is about a 450 pound difference which is typically good for 0.450 seconds quicker in the 1/4 mile, using the 100lbs is worth 0.100 seconds rule.

A turbo is a legal muffler. my turbo with 2-1/2 pipe going to a dynomax turbo muffler (stock mount position) sounds stock.

worth 5K if it as running.

run 20 degrees at idle. I would ramp up to 45 degrees while going down the highway (no boost, high vacuum). and drop to 20 during boost.

400hp crank will make about 320 at the wheels.

The stock turbo can make 250hp. Otherwise, the T04E-50 trim is a better fit on a L28 than the 60 trim. If you plan to use the stock cam them use a stock L28et turbine. If you add a stage 1 msa turbo cam then use a stage 3 or 5 T3 turbine. The turbo will need carbon seals for a draw through setup (gas in the compressor). Another option would be to use a 4bbl intake and make a blow through turbo setup. A draw through will not work well in cool conditions (under 50 F). http://www.squirrelpf.com/turbocalc/graph.php?version=4&pr0=1&pr1=1.07&pr2=1.41&pr3=1.76&pr4=1.76&pr5=1.76&pr6=1.76&pr7=1.76&airflow0=3.1&airflow1=9.5&airflow2=13&airflow3=16.6&airflow4=22.9&airflow5=26.9&airflow6=29.4&airflow7=30.1&product_id=57

try another compression gage. the gage can be wrong. pull out all 6 plugs when doing the test and open the throttle. low cranking pressure is typically caused by a stretched timing chain. Try advancing the timing chain to the 3rd position. read the repair manual carefully how to do it. bad mpg can also be caused by retarded ignition timing. Make sure the mechanical advance to working and make sure the vacuum advance is working. Do you have a timing light? are you using points or electronic ignition? work the choke levers and make sure they return to the non-choke position. adjust the idle mixture for best idle (highest rpm and highest vacuum). Look for gas leaks.

they seem to tap off fairly easily. use a lot of soft hammer blows instead of a few hard ones.

if your 2-1/2 pipe is in good shape then use it for now. Get the car running first and upgrade the exhaust later. I'm using 2-1/2 inch mandrel bent system and a dynomax turbo muffler with a msa turbo stage 1 cam, full boost by 3500 and power to 6500. t04b-h3 compressor with a T3 stage 3 turbine. makes around 275hp with 13 psi of boost (110 mph in the 1/4 mile).

5's should be good enough for mounts. use 8's on things like flywheels and pressure plates.

The poster seems a little green. He needs to know what he is getting into and needs to know about other options. I'm sure many V8 conversion have never been finished due to cost over runs and fabrication issues. While a turbo project is much easier to complete in both cost and skill required. For most people, a V8 conversion falls into the subject of "be careful what you ask for".

A T61 would work, if you go by the compressor maps http://www.squirrelpf.com/turbocalc/graph.php?version=4&pr0=1&pr1=1.07&pr2=1.64&pr3=2.22&pr4=2.22&pr5=2.22&pr6=2.22&pr7=2.22&airflow0=3.1&airflow1=10.2&airflow2=16.9&airflow3=24.5&airflow4=30.6&airflow5=34.4&airflow6=37.1&airflow7=37.9&product_id=68

ok, here is a T70, 2.8 liter engine, 18 psi of boost, 3500 rpm max boost. http://www.squirrelpf.com/turbocalc/graph.php?version=4&pr0=1&pr1=1.07&pr2=1.64&pr3=2.22&pr4=2.22&pr5=2.22&pr6=2.22&pr7=2.22&airflow0=3.1&airflow1=10.9&airflow2=17.4&airflow3=24.5&airflow4=30.6&airflow5=34.4&airflow6=37.1&airflow7=37.9&product_id=72 if that red line is to the left of the surge line then the turbo should surge. It just doesn't make sense that compressor would work on a L28. But, it is working for you so hard to argue that.

drill and tap the head. not hard to do.

http://www.squirrelpf.com/turbocalc/graph.php?version=4&pr0=1&pr1=1.07&pr2=1.54&pr3=2.01&pr4=2.01&pr5=2.01&pr6=2.01&pr7=2.01&airflow0=3.1&airflow1=9.5&airflow2=14.1&airflow3=19&airflow4=26.1&airflow5=31&airflow6=33.6&airflow7=34.3&product_id=72 here is a T70 on a L28 making 350hp at 5500 rpm. full boost by 3000 rpm. should be all surge. are you sure you have a T70 compressor?

a friend of mine just dyno'd a junk yard turbo engine. Just pulled it out of the junk yard, changed the head gasket, and ran it. He made 200hp and 240ftlbs of torque with 7 psi of boost with a used IC. Turning up the boost to 12 psi should yield 242hp/290ftlb at the tires or 290hp/350ftlbs at the crank. A $1000.00 small block conversion will not make that power. Plus the chevy would still need a transmission, drive shaft, mounts, and all the other stuff to get it in there. My turbo will out run my friend V8 conversion, mostly due to more gears on my car versus the automatic. His engine is making the same power as mine (330hp at the crank) using dart heads and a mild cam (260 degrees). However, my v8 conversion is faster than my turbo. Crazy fast. Actually too fast, but that is another story. But it isn't nearly as nice to drive as the turbo (ac, smooth idle, quiet, ect) and the V8 took a lot more time and money to get it going.

forget the V8. it is a much tougher swap than you think. plus it will cost much more than 2000.00. Buy a complete, running, rusted out 280zx turbo car for 1000.00 and swap everything over to your car. It will be faster than a cheapo V8 conversion and will take 1/4 as much time and will be a much better daily driver. Plus there is a lot of room to grow with a turbo setup.

Run block huggers headers into 2-1/4 duals into a H pipe after the transmission, then run 2 dynomax bullets, then Y into a single 3 inch pipe right before the diff, then put a 3" turbo style muffler on the end. The loudness depends on the rear muffler. A hooker aerochamber on the rear gets a little loud for an old guy but will make the sound you want. A large case dynomax super turbo will make it sound stock in all cases except at full throttle. The H pipe and dynomax bullets before the rear muffler are required to stop the drone. I built a system like this on a 77 280 V8 conversion last year. I first built it without the H pipe or the dual dynomax bullets and it was undrivable due to massive droning.

My advice would be to calculate the time, money, and work for the project. Then sit down and double those numbers. Especially if you are after a good daily driver and not a just a quick trip car. I don't want to discourage you, just want to get you prepared for the job. good luck!

Nice car. But, a T70??? That compressor is so big that it would be to the left of the surge line for the entire power band. Does it boost at all?

The P79 head and the P90 head will run about the same. There is no need to change the P79 head. If you what more rpms then add a cam with more duration and lift. The turbo cam has even less duration than the NA cam. (around 8 degrees less) I would just send your stock cam and rocker arms to DeltaCams for a cam regrind and rocker-arm resurface. Then install some 0.160" lash pads from Courtesy Nissan (Dallas, Texas). You can get the cam and rockers done for $110.00 and the lash pads for $36.00. So about 150.00, your engine will have a cam with more duration and lift. I would only use a 260/260 degree cam with about 0.425" with stock springs and stock efi. A stock L28 cam is around 248 degrees and 0.400". 12 more degrees and 0.025" more lift will be good for another 750 or maybe 1000 rpms of power band. A 2-1/2 exhaust system would also help use zddp oil additive with the new cam (http://www.zddplus.com)