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Silent Assassin 6.0l Z31 build thread


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This is my first post even tho I have been lurking around for about a week since I found this awesome site. I officially took possession of my second "Z" car today. My first was a '77 280 5-speed with a k&n and a flowmaster muffler with no cat that I fell in love with when I figured out it ran its best when I reved it to 4500 rpm and sidestepped the clutch and speed shifted it like I stole it. The car would squat so hard it banged the bump stops and spun both rear tires for about 5 feet and was usually ahead of most of my buddies v-8 cars. That was back in 1989 and when I ran into the back of an s-10 blazer while turning the dials on the cassette radio I was crushed just like the front end of the car. That was the first of two wrecks I ever caused.

 

Anyway on to this build and the name. I have been searching for a car to do an LSX build in for a while now. A buddy had this car and since he had no mechanical experience at all I talked him out of this 1987 N/A 300zx for a steal. I busted my butt today airing up the tires and loading it on to a car hauler. Someone had begin swapping over the base blue cloth analog interior for tan 30th digital leather interior from a 2x2. Most of the panels were just shoved in the car and the seats were sitting outside under a lean to cover. I cheated and washed the car and vacuumed the carpet of all the rat dung before taking pics of the car.

 

The premise for this build is to make a quiet sleeper street car. The car will be used to help promote my internet mototsports show called the Thunder Road Show. You can hear our show at www.thunderroadshow.com. Anyway the final product will be a 6.0L with at least one turbo backed by a 4L80E trans and 8 second time slips on drag radials and full exhaust so its real low key. I want to hear the tires ripping to shreds on videos not the motor. I love the idea of blow trough carbs and e85 so thats what this car will get to help keep costs down. I have secured a complete 6.0L intake and all out of an Escilade that was totaled on a test drive and has about 150 miles on it. I also have the tranny with a fresh rebuild out of a dually and will be selling the complete 3.0 and tranny from the '87 plus everything I dont need like air box, computer, wiring harness stock drive shaft and 6.0 truck intake, injectors and what ever else I don't want.

 

The build will start with a prosystems carb and a plate nitrous kit then move on to one large or two medium turbos with no intercooler. I plan to run the e85 and may experiment with nitrous and boost. I'm kinda crazy an understand all that will come when the bottom end is forged. I plan on running a 2002 z06 cam with 1.8 shat rockers as to keep the motor low key even tho I love how they cut up with large cam.Here are some before pics of the junk and will update every time a do something else to the car.

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Thanks for the info Noobz. I will update often. I washed the mildew off all the interior parts yesterday and started laying them out where they go like im putting together the pieces of a puzzle. Since the tan interior came out of a 2x2 the headliner that is in good shape is too long for my car so I am thinking about just cutting it down instead of trying to find another good tan one. Also the panels that cover the front of the wheel wells are too long so I am going to have to make or find shorter ones. I still need to paint the glove box door tan as I only have the blue one. I also think I am going to paint the e-brake handle as the tan one is not in very good shape and just buy a billet cover for handle itself.

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  • 2 weeks later...

A few updates. I got the v6 to start for a few minutes it purred like a kitten. I revved it a few times and then it started missing and died. I replaced the fuel filter but it didn't help. Took the filter off and no fuel even when cycling the key. I had added 5 gallons of super to the tank of old smelling fuel. I then hand pumped 16 gallons of fuel out and the tank has a bunch of rust and crap in it so I am pulling it and either going to have it cleaned and a sump put in with dual 8an lines.

 

Some of the interior parts dont fit like the headliner (2x2), front wheel tub cover panels are too big also and the door handle is in the wrong spot so the tan door panels wont fit.

 

The good news is I found a set of silver 17x9 mustang bullet wheels with tires for a good deal and I am picking them up tonight. I will post pics later tonight when I get them mounted.

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So I pick up the bullet wheels and they are as advertised in great shape. I had to try them on so I slapped on one side. The wheels have stock '09-'11 mustang tires on them that are 235/55r17's. They are right at 27" tall and fit great in the back which means I have plenty of room to run a 275/50r17 mickey thompson drag radial. The fronts hit the bottom of the strut mount for were the spring rests. I am sure they would work with coilovers but I am going to just finds some used 245/35r17's and put them on the front. This will actually give the car a little "rake" and may look ok. Here are some pics I took tonight. I will post some daytime ones when I get the front tire issue fixed.

 

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I don't know if anyone is even following this build and I know its not really that exciting so far. I do have a few new updates. I ran a hotshot to La Grange Texas today and stopped by a salvage yard. I decided to try one outside of Houston cause that can be a wild goose chase in the big city some times. Any I scored a pretty good deal. At least I think its a good deal. I got a new hood with two little rust holes in it but its way better than the beat to hell one that came with the car. I also got all the interior parts I needed for a 2 seat z31 except the headliner. I got all the pieces for the hatch area, two new door panels, the carpet for the back with the handle and the storage tray for behind the seats. Plus a shifter boot. Its all red but I will paint it all tan tomorrow. All this I got for $100 so not bad even tho I had to pull it myself. I got all the screws I needed. I'll post some pics tomorrow.

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New update. I picked up the hood I thought I needed from the salvage yard and it seems there was a design change from '86 to '87. The hood looks the same but is too narrow between the headlights and is too short. I had already done all the pre paint prep work like patching a couple of rust spots and spraying the entire hood in epoxy primer. I wasted about $100 bucks in labor and materials for a hood that will shut but is too short. I am looking around Houston for an '87-'89 hood that I can swap with a salvage yard.

 

In other news I ordered a really nice aluminum 15 gallon fuel cell with a sump and sending unit. It should be here this Wednesday and I will post pics then. It is supposed to be brand new and polished already. I also purchased a frame mount fuel pump off of an '89 Ford f-150 that is 120Lph and that should be more than the stock pump. I debated on flushing the tank and adding a sump but found this fuel cell on racing junk for $165 new and could not resist. The pump I purchased at O'Reilley and if it goes out I can get it anywhere. When the new motor goes in I will add a second pump like this one and have it come on under boost. Here are some pics of the tank and the nasty crap that killed the pump. When I got this out I am was stoked that I had already ordered the cell.

 

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Here are some pics of the interior as I was painting it to match the tan in the car.

 

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Here are some daytime photos with the new wheels and toyo 255/40r17 road race tires on it. I really need to lower the car about 2" now

 

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There was a styling update in late 87 (I think 4/87 build date cars were the transition).

 

http://www.vgpowered.com/vehicle-lineup/2-sports-cars/4-nissan-z31

 

 

Thanks that information was interesting. I have been a mustang guy since the late '80's and don't know these differences in these cars like I do mustangs.

I wish I would have known the difference before I did all that work to the '86 hood. On a positive I found an '87 hood in town yesterday for $100 and all it needs scuffed and painted.

 

I am still planning on installing the 6.0L turbo setup but wanted to get the car and interior, wheels and tires lined out before I start the motor swap. I'm glad I did since I had all the problems with the tank that could have ruined a new carb.

 

Here are some pics with the new hood and the front clip ready for paint.

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I don't think you'll have room for a carb without cutting up your new hood. My LS1 intake has maybe 1" of clearance under a stock 88' hood. Might want to do some looking before painting it. I know I've seen a few carbed SBC swaps floating around here somewhere, but I can't recall if they ran cowl hoods or not.

Edited by i r teh noobz
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I don't think you'll have room for a carb without cutting up your new hood. My LS1 intake has maybe 1" of clearance under a stock 88' hood. Might want to do some looking before painting it. I know I've seen a few carbed SBC swaps floating around here somewhere, but I can't recall if they ran cowl hoods or not.

 

 

I already know that I am going to have to cut a hole in the hood. My best friend owns a body shop so repainting the hood won't be an issue. My plan is to get the two tone done and drive the car with the 3.0 till I get all the parts for the 6.0 blow through set up then do the swap in as short of time as possible all the while working out the kinks in the car as far as suspension, brakes, gauges stuff like that. I don't want to run a cowl hood and I know that the bonnet that I have to use for a blow through will stick out of the hood. My plan is to get the motor installed with the turbo then make a template and carefully cut the hood to fit tightly around the bonnet. At that point we may find a scoop or something to cover the polished bonnet. Depending on how much it sticks out we may fabricate an old school tear drop or use a ss camero forward facing scoop to cover up the bonnet.

 

Thanks for the advice,

Doug

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Update.... I got the door panels and most of the rest of the interior painted and installed. Everything except the seats, carpet, dash and center console were red. I scuffed and painted the door panels and all the rear hatch area panels. I am not leaving the red carpet in there I just got tired of looking at the nasty floor pans.

 

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  • 2 weeks later...

Update Update!!! I finally got my fuel cell in so I can get the car running and to the paint shop soon. I found this company on racingjunk.com and called them directly and ordered it via pay pal for $169.00 plus shipping. It took almost 15 days to get it but it is exactly like the photos. Its a 15 gallon polished cell with a sending unit and all needed fittings for a vent and return. It has a little bit of foam and a sump with #8 outlets. I cut out this piece of 1/2" MDF board as a nice flat floor for the cell. I will have the wood covered in tan vinyl at an interior shop.

This is also my first steps toward the LSX converion.

 

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  • 3 weeks later...

OK a quick little update on my build. I have been doing some electrical work for the guy I am buying the 6.0L engine from so its almost mine. In the mean time I am getting all the bugs worked out and getting the inspection and tags up to date. The fuel cell is mounted and instead of covering the floor of the trunk area in foe leather I decided to save the money and put it towards getting the car running and all the bugs worked out. I put an electric fan on the car and gave away the clutch fan, I trashed all the factory air box stuff and installed a cone filter. Replaced the washer blades and got the tail lights and turn signals working (thats a whole other story). I lowered the car 1.5" all the way around and fixed an intake boot that was coming off. I removed the a/c compressor (no freon). The car runs really good and with a 100 shot of gas would probably be a little fun. Tonight I am fabing up a chevy truck tail pipe as a (in front of) cat back. Yeah were going off road now baby. Next up is paint then saving up parts for the LS2.

 

Here is before and after lowering

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Edited by LSXZ31
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Latest update. I got the car lowered and love the way it looks but after adding my big 3" exhaust I think I may raise the back up about a half of an inch or so. I will post pics of the exhaust after I make one change to the system. We used a mandrel bent tail pipe off of a chevy truck and since I didn't have a pipe bender we ran the pipe under the rear sub-frame. We started with straight pipe and no cat. That was a lot too loud for me so I bought a knock off flowmaster one chamber and added it to the front part of the new system so that the aft pipe would change the tone from every other 6 cylinder car out there with bumble bee exhaust. I know the 6.0 liter and turbo will quiet it down a bit and if not I will add a bullet or other straight through muffler. Right now its kinda fun. Here is a video I made before and after the exhaust swap enjoy and please comment. The sparks were mainly from the oem hanger on the truck tail pipe.

http://www.ihigh.com/thunderroadshow/video_896790.html

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Are you mounting that fuel cell in the hatch back area? If so, your going to be getting alot of fumes.. My neighbor has a hatchback GT and his cell is mounted that way.. I cant stand to ride in it... But his isnt a street car.. Might also check with the state to see if its even leagle to mount it there..

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Are you mounting that fuel cell in the hatch back area? If so, your going to be getting alot of fumes.. My neighbor has a hatchback GT and his cell is mounted that way.. I cant stand to ride in it... But his isnt a street car.. Might also check with the state to see if its even leagle to mount it there..

 

 

Yes the cell is in the hatch area. If you properly vent the cell outside of the car and use an style fittings you should never have any fumes unless your gas cap is bad. My vent exits the body and has a filter on the end of it so bugs won't crawl up inside and dust wont get up in the tank. The NHRA requires a firewall separating the cell from the cockpit so I will be adding one of those soon. I have been driving the car around a lot and no fumes but I also don't have a/c so the windows are open.

 

The state of Texas is not real strict on stuff like this as I got the car inspected yesterday. So with the fire wall that will be sealed and when I limo tent the back glass you won't even see the cell unless im filling up and you roll up behind me.

 

I don't know why your buddy got so many fumes but I bet he had a plastic cell and it wasnt installed correctly.

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  • 1 month later...

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