Pyro

I have tuned a 8.8:1 cr L28 turbo engine and it could only take 17 degrees of total ignition timing at 8 psi of boost with 93 octane. I would use the vacuum advance, as it help gas milage. boost will shut it down. sounds like the distributor mechanical advance is locked (this is the typical setup for a retro fit turbo setup). you need to figure out your ignition system, as this is critical for the engine to live on boost. check to see if the mechanical advance is locked, what the initial timing is, total timing, and what the msd is doing on boost (how much retard) I can run 27 degrees of ignition timing on my 7.4;1 cr engine with 13 psi of boost on 93 octane. 8.8:1 cr at that same boost could handle maybe 12 degrees. (big difference). better to run less compression and more boost and timing.

you need the head gasket that matches the block (n42). if you put a F54 head gasket on a n42 block then it will over heat. what kind of efi system are you using? what does your ignition timing curve look like?

have you seen these? http://www.autozone.com/autozone/parts/1976-Nissan-Datsun-280Z/Head-Spacer-Shim-Gasket/_/N-int6pZ8zq8p?filterByKeyWord=head+gasket&fromString=search head shims to make up for too many head resurface jobs. works with a stock head gasket. nissan head gasket should be 1.25mm and this shim is 0.50mm which will make 1.75mm (very close to 2mm and much cheaper). The issue you will have with a thick head gasket is it will advance the cam, which increases cylinder pressure. An adjustable cam gear sprocket is the fix for a thick head gasket but is expensive. If you are using the stock gear setup then install it on the 1st position and hopefully the chain is old and stretched a little. another fix is to run a bigger cam. a bigger cam "bleeds" off cylinder pressure due to a later closing intake valve. Send your stock cam for a regrind. Deltacams can do if for $60. For a turbo setup, just regrind the intake lobes for more lift and duration. go to 260 degrees of duration and 0.420" lift on the intake lobes and add 0.160" lashpads to make up for the regrind (courtesy nissan, 3.00/each). This will help reduce detonation and make more power.

like putting a 2.8 liter block under a 2.4 liter head, the compression goes up. using KA24DE pistons in a 3.1 liter you will make 8.5:1 cr with a 1mm head gasket and a p90 or p79 head. If you install a 2mm head gasket then the compression with drop to 7.8:1 cr. Still not to the 7.4:1 stock level. Furthermore, using 8.5:1 with a turbo is not good with a stock cam. Ok for low boost (6 -8 psi) but will require a bigger cam to run higher boost. 7.8:1 cr isn't that bad but the 2mm head gasket is expensive, kills cylinder head quench effects, and requires the use of an adjustable cam timing gear (more money) do the higher head install. so not worth building a 3.1 for a turbo unless you use custom pistons to select the right dish size (big $) or if you plan to use a big cam like a msa stage 2 or 3 turbo cam (but not street friendly cams).

350 hp at the wheels or the crank? You will need a bigger cam if you plan to make 350 at the wheels with boost under 20 psi. cost $1000 to do a "stock" rebuild (with new pistons). add another 1000 for the turbo, wastegate, and the bigger exhaust system, and stronger clutch. then another 1000 for the standalone efi system and intercooler. with a 3K budget I think you need to stay with a stock 2.8 and use a NA cam with a T3/T04e-50 trim turbo with an intercooler, 240mm clutch setup, 3 inch exhaust. Go megasquirt and use 18 psi of boost and make 300hp at the wheels (360hp). and this will most likely cost 4K.

forget the 3.1. not an easy or cheap build. and hard to get the 3.1 liter compression low enough for turbo charging. just rebuild the 2.8. bore the block 1mm and put in new stock pistons (+1mm). The machine shop can handle this easily. This is a small detail. very small. then put the "bigger" turbo on the 2.8. The difference between a 2.8 and 3.1 is about 2 psi of boost. so just add a little more boost to the 2.8 to make the same power.

a laser turbo (2.0 liter) is too small for a 2.8 liter. the turbine is too small. best to use a stock T3 from a 280zx or 300zx first gen. easy to add a turbo to a 280. just bolt on the stock turbo manifold, stock T3 turbo, stock wastegate, stock downpipe, stock j-pipe, stock oil feed line, stock feed line tee, stock drain line, and stock turbo oil pan. All these parts can be obtained for cheap. no need for a "kit" because 280zx's came from the factory with turbos. go to your local U-Pull-It junk yard and get the parts from a crashed 280zxt or get the parts from the classified area. a used turbo and wastegate and down pipe assembly goes for 50.00 to 60.00 at the junk yard and 150.00 in the classifieds. then lock out the mechanical advance in the distributor and set timing to 24 degree with 8.3:1 cr or 20 degrees with 8.8:1 cr. use the vacuum advance as normal. then install a 8:1 FMU (ebay, 100.00) in the return fuel line after the fuel rail. this adds more fuel when the boost comes on. with stock boost, this setup is good for a mid 14 second 1/4 mile at 95mph in a otherwise stock z.

I have run both the world class T5 and non world class T5 in my drag racing 240 with 650hp. (450 + 200 shot no2) and I can't tell the difference. the difference between the WC and NWC is the syncro material, not the strength. the V8 T5 is stronger than the V6 (don't use a V6 T5). slow shifts and normal size radial tires will allow the T5 to live a long life. Get the NWC T5 if that is the one you found and run it without any worries.

300 or 400 dollars will not go far. yes, install better exhaust. small turbos like big exhaust 2-1/2 to 3 inch will do nicely. I would also use mandrel bent pipe at the back (S-turn). get a J-bend from summitracing.com for the exhaust shop to use at the back. I would pass on "buying" a down pipe with that budget. FYI, making a down pipe is easy and cheap. Then I would install an intercooler. bar and plate style from e-bay, not too big and not too small (around a 8 x 16 x 3 inches thick). Plumb in the ic with mandrel pipe and silicone connectors (again, summitracing.com) then lastly add a manual boost controller and run 10 psi of boost. that should get you to around 210hp at the wheels and stay within the budget. I would think you would need better exhaust and intercooler to see noticeable gains from megasquirt.

buy a new z evaporator core that takes a standard style expansion valve that works better with 134.

here you go. 490hp, 525ftlbs with a 400 sbc on 87 octane. http://www.chevyhiperformance.com/techarticles/148_0401_chevrolet_406_ci_engine_build/index.html

to make 400hp at the wheels then the engine will need to make 480 at the crank. to make 480 hp with 10 psi of boost then the engine will need to make 285 hp before turbo charging. (1.68 x 285 = 480), 10 psi pressure ratio = 1.68 to make 285hp with a 305 will take a little head work or a "good "set of heads and a small cam (not a stock cam) if you run a set of L28 T3's then you can't use any valve overlap due to restrictive exhaust turbines causing lot of back pressure. So a cam with around 260 degree on the intake, 250 on the exhaust with 114 lsa, then a maybe set of vortec heads will get you to 285hp. (maybe) then add 10 psi to get to your 400hp at the wheels goal. a stock L28 T3 will "max out" between 200 and 250 wheel hp, depending how you define "maxed out". so that is 400 to 500hp with a twin setup. if you just add 7.5 psi of boost on a stock 200hp engine then it will only make 300hp (1.5 x 200 =300), 7.5 psi pressure ratio = 1.5 hard to make a lot of power with a 305 due to the small bores which restrict the flow from the heads (small valves and small ports). better to use a 350 (big bore).

11;1 cr should be ok if the cam is big enough. I would say a cam with 292 to 300 degrees (seat to seat) with 110 lsa would be enough to drop the cylinder pressure to run 93 octane. a cam this big would would well with a 3.90 gear and early 5 speed. figure out the dynamic compression ratio. 8 to 8.25:1 is a good number for pump gas and a L28.

I moved my afm in front of the radiator support. mounted up high near the hood. Cut the afm wires and extended them about 18 inches. ran 2-1/2" mandrel bent pipe to the afm from the turbo inlet and used a little k&N filter on the end of the afm. works great. Moving the afm out front makes more room to run IC piping in the engine compartment. Then installed a Bar & Plate IC under the AFM.

I would use the scarab mounts with an automatic transmission and the JTR mounts for a manual transmission.

I feel the pump will last longer due to less pressure on the pump. the return is the same size as the feed line and it flows very well. I did a test a few years ago. just looped the fuel directly back to the tank with no fpr. Just a Tee at the point the feed line returned back to the tank (by the filter) and measured the pressure at the tee. measured between 1/2 and 1 psi at the tee, which means the stock return line is more than big enough to reduce the pressure. furthermore, efi pumps lose fuel volume with more pressure. So, at 5 psi, the stock efi pump will flow lots of fuel, much more than at 30 psi. and there isn't any "built up pressure between the pump and regulator" . The built up pressure is only equal to the pressure at the regulator due to the return line.

I helped a friend on mine do exactly that; supply a carb'd 350 sbc with a stock efi pump (msd 2225 efi pump). has a 77 280. He went from an efi turbo setup to a chevy 350 with a Q-jet. we just regulated the pressure down to 5 psi with the aeromotive fpr (return style) and no problems for 2 or 3 years now. And the car is a major daily driver (250+ miles/week)

hp gains with long tubes versus shorties will depend on the engine build. the more radical the build, the more long tubes make over block huggers. I have seen a header comparison using a 350 with a compcam 292H (244/244 at 0.050). The long tubes made 75 more hp over cast iron log manifolds and 35 more than the block huggers. I used a set of hooker headers made for a datsun V8 conversion. But took lots of work to get them to fit in a JTR engine position.

nothing wrong with using the stock efi pump for a carb. just get a return style fuel pressure regulator that can go down to carb pressure aeromotive makes one that will work for 120.00. check it out at www.summitracing.com

you can run the turbo without water cooling. I have been using mine that way for over 5 years. Majestic Turbo told me I didn't need to use water cooling and I didn't feel like running water lines.

I would think a 3500 rpm power band would be ideal, anything less is not correct. but the problem remains even with the 0.82, should not have any creep issues. There is some sort of wastegate issue. I run a t3 turbine, 0.63 with a stage 5 and makes full boost at 3500 and pulls to 6500 with a msa stage 1 turbo cam. no creep issues at all. But wish I would had keep the turbine stock. the power band is a little too short

I would run the 0.63 also. but use a stage 5 turbine setup. you should get full boost by 3500 which will work nice with a 7000 rpm redline. creep is normally caused by a wastegate problem or a wastegate that doesn't flow enough. I had a creep issue until I increased the size of the stock wastegate hole and smoothed out the edges leading up to the exit hole inside the turbine. what wastegate are you using? I also had a recent spark plug issue on my turbo. Ended up being caused by loose spark plugs. I wasted lots of time and energy trying to find that problem. Champion spark plugs work very nice on L28's.

boost is a hp multiplier 14.7 psi of boost will double hp. if you add 14.7 psi to an engine that makes 175hp off boost then it will make (in theory) 350hp. I figure a stock turbo engine with 7.4:1 cr and a cam with only 240 degrees of duration makes about 125hp at the wheels without boost. add 15 psi of boost and make 250 Add a stock NA cam with 248 degrees and do a little head work to get 140 hp, then add 15 psi and make 280 add a bigger msa turbo stage 1 (260 degree) and get 150hp , add the 15 psi and get 300. use the pressure ratio and the hp multiplier. (14.7 + boost)/ 14.7 so if you start out with only 125hp then you will need to use lots of boost to get to 350.

get a 044 bosch amazon has the best price ($169) http://www.amazon.com/Bosch-044-Universal-Inline-Fuel/dp/B001CCVFBS you will also need some fittings from summit racing to convert the metric threads to -AN, then -AN to NPT if you like. if you want to keep the check valve in place, then you will need a banjo fitting and a closed end metric nut (I made my own banjo and nut). if the pump is loud then the pump isn't getting enough fuel. The msd 2225 pumps are quiet if they get enough fuel. the 044 is louder than the MSD 2225. I run my 044 on the stock fuel pump wiring then use a hobb switch to give it full battery voltage after 2 -3 psi of boost. The old fuel pump wiring on my car only delivered 9 volts to the pump (you need to check yours). I use the 9V to keep the pump quiet until I need the flow. my tank is dirty so I run a 100 micro filter before the pump (aeromotive makes good ones, again amazon had the best price). Finally, I mounted the pump even with the bottom of the tank. I run NA injectors (190cc) with 11 to 14 psi of boost so pressure and fuel are important. I use a 8:1 FMU to increase fuel pressure for fuel enrichment. 11 psi of boost gets 88 psi of fuel pressure, 12 gets 96, 14 gets 110+ psi. The pump makes the pressure and holds it well (I have a gauge in the car), so it puts out good volume even at high pressures. Again, if the pump is loud then it isn't getting enough fuel and the pressure will drop. I had an issue right after I installed the 044. it was loud and didn't make more than 50 psi on boost which is a big issue with a fmu. I too off a 60 micro fuel filter that was clogged with very fine rust ( before the pump) and that made the pump quiet and allowed it to deliver 100+ psi of fuel pressure. finally, my intake line from the tank is party clogged (didn't give enough fuel) so i had to drill and tap the drain plug to a 1/4 npt for a 90 degree fitting with a hose barb. I know my intake line was party clogged by comparing how hard is was to blow through versus another tank in good condition.

you can use the stock 280 efi for now with your fmu. use an 8:1 ratio. 8 psi of boost needs 64 psi of fuel pressure then lock the ignition mechanical advance and set timing at 26 degrees with 8.3:1 cr and 8 psi of boost. I would get a fuel pressure gage mounted in the car so you can keep track of the fuel pressure.