'80 Stepside LS9 build

[Ofnaman1]

Since this is pretty much a complete rebuild of our rebuild, I decided to start a new build thread for this truck. Here is the original thread: http://www.67-72chevytrucks.com/vboa...d.php?t=599469


The truck originally started out like this when we got it in 2013. It was a heavy half with a 350/350 and a 12 bolt. It had been sitting for a couple years from what the previous owner said. We drove it home 20 miles and immediately started tearing it down.

[Ofnaman1]

So, we originally built the truck with a L96 6.0 (stock engine, headers, and a tune), it had a 6l90e trans and a 12 bolt truck rear end (3.73 gears, auburn posi), and a complete frame off rebuild. It was great. The truck performed like you would expect, and got great fuel mileage (when we could keep our foot out of it). We really only put about 1700 miles on it in that form. We took it to Hot August Nights 2017 built like that and had great feedback from people. Shortly after that the decision was made that the truck needs more power. What started out as a "lets add a turbo to it" snowballed into what we actually did. I started researching turbo kits and engine parts. If we were going to build the truck again, I wanted it to be right. The L96 is actually a great engine to build off of as it already pretty much has ls3 heads on it and a good block. The problem we kept running into was the 6l90 and the factory wiring/ecm. To be honest, the setup was so good I just did not want to tear it apart, but rather build something else and keep this for a future project.

That's when we start getting into the LS9 stuff.... I just happened to have a complete LS9 (super charger to oil pan) in my garage that needed a rebuild (dropped a valve on #2 and destroyed the bank 2 head and all the bank 2 cylinders/pistons). Instead of tearing the 6.0 apart and building it, we decided to go the ls9 route and save the 6.0/6l90 combo for another project, but as soon as bills started coming in for the ls9 build, we ended up selling the 6.0/6l90 combo and the 12 bolt out of the truck. Most people are not aware of this (even the machine shop guy's....), but the LS9 is completely different than any other LS based engine, like, everything is different, and is pretty much ls9 specific. Yes, you can interchange parts with other ls engines, but to keep it pretty much all ls9 it is really spendy.


I started the LS9 engine build by doing as much research on this engine as I could before ordering anything. The LS9 uses a LS9 specific block, crank, rods, pistons and heads, and the stock components are really good. We took the block to the machine shop to have it checked, and got good news. The block only needed a minor overbore to clean up the damaged cylinders. So we started gathering parts. I wanted to keep the stock titanium rods as they are really strong and light. In order to do that we had to have custom pistons made. You can get overbore pistons from GM for the LS9's but as a GM employee, they still would have cost me $3500 for 8 of them.... We ended up having stock compression Carillo pistons made (still cost $1800....). We had the factory crank balanced at the machine shop as well. Once we got the engine back, I started assembling it. The engine has factory billet main caps, so I just got a set of arp studs for the mains and called it good, I was able to use normal LS main studs, they are the same for all ls engines. I also used arp rod bolts (same for the LS7 and LS9). The head studs however, are different. The ls9 uses 12mm studs, so we had to order a set up from Katech (they are arp studs, but you can only order them from Lingenfelter or Katech). We had to buy one new head as the bank 2 head was beyond repair. I bought a bare head and replaced the titanium intake valves and steel exhaust valves with new stock units. I used comp cams double valve springs (I cannot remember the # off the top of my head) and tool steel retainers on them. I then installed a Lingenfelter GT9 cam and used Chevrolet performance 8000 rpm lifters in it. The crankshaft uses a 9 bolt flywheel, and there is only one company that makes a flexplate for the ls9 that I could find, JW. I installed that, and had to buy 2 sets of arp LS flexplate bolts to mount it. Moving on to the supercharger, we modified it with the Lingenfelter snout and 2.35 pulley. Mounted it with arp studs. As of right now it has stock injectors in it (soon to be changed). We decided to be different and actually run the dry sump oil system. That was challenging, but I like the way it turned out.

[Ofnaman1]

Couple more engine pics

[Ofnaman1]

We backed the engine up with a Hughes 34-1X th400 transmission, and a Hughes LS Torque converter (I cannot recall the part # off hand), sorry no pics of this prior to install.

The decision was made that the 12 bolt is no longer up to the task, so we called up Dutchman and ordered a narrowed 9" for it. They had a deal on wildwood disk brakes at the time so we got those also. When it showed up, I got busy assembling it. It was only narrowed 1" from the stock 12 bolt width. We got 3.70 gearing and a true trac diff in a strange housing. The assembly was very straight forward. I cannot say enough about Dutchman, they were very easy to work with and their stuff is top quality.

[Ofnaman1]

We originally planned on a 4 link or ladder bar setup and full on back half, but then I started looking at rule books for racing and decided I wanted to be able to run it in street classes that required a "stock style" suspension. So we ordered a set of calvert racing split mono leaf springs and caltracs. I haven't had it on a track yet, but on the street they make a huge difference. Ride quality seems to be the same as before. Please don't hate on the shocks/shock mounts in the picture, they were a last minute setup to get it on the road quickly, we will be changing those for sure.

[Ofnaman1]

This is what the engine originally came out of. Yes the car is still on the road, I replaced the engine and supercharger with new units. The car actually only had 7500 miles on it when the valve dropped (the owner did not have a clue how to drive it, and overrevved it while shifting into the wrong gear).

I still do not know why some of pics post sideways.... They are the correct orientation when I select them.

[Ofnaman1]

Pics of the removal of the 6.0

[Ofnaman1]

Install of the ls9

[Ofnaman1]

We wanted to be able to run the engine cover on the ls9, so we had to rethink the brake booster. I ended up deciding on hydroboost and sourced a unit from a newer Silverado. I had to heavily modify it to work, as well as flip it upside down for extra clearance. It works way better than I was expecting, much better than the vacuum booster and I am very happy with it, plus it looks cool....

[Ofnaman1]

Here are some pics of the oil semi finished engine bay.

[Ofnaman1]

I did not get any pics of it, but we are planning on running ac in the near future, that is why the heater core is not hooked up (plus the 2 year old heater core is already leaking.....). We put a concept one ac compressor/bracket kit on it. I tried my hardest to mount up a sanden 508 compressor on my own, and actually made a cool bracket for it, but in the end it was too wide for the frame. We ended up throwing in the towel and bought the concept one kit. It is very nice and uses a mini sanden compressor. I thought I had some pics of it, but I cannot locate them.

[Ofnaman1]

I had it on the rack yesterday, so here are a couple under belly pics. We had a brake fluid leak and it took out some paint on the frame, I haven't had the time to fix that yet.

[Ofnaman1]

We had it at a few events for Hot August Nights 2018 like this, but had some issues with driveability. I had it together about a week before the event and it ran great for a couple days. Then during the week of hot august nights, it started running poorly. I thought it was a tune thing, and it was scheduled for the dyno tune on that Friday, so I did not worry too much about it. We got it to the dyno and it would not run above 2500 rpms. They found it was loosing fuel psi above 2000 rpms. Well, we ended up just parking it for a while because I was moving into a new house the next week and did not have time to mess with it. I just couldn't wrap my head around what was going on with it, and it drove me crazy until I finally got to it this Saturday. We should have had more than enough fuel system, at least I thought..... I put two walbro 450's in the tank with dual -6 an lines running to the regulator, from there -8 to the rail. We were still running the stock injectors and we knew they would limit performance, but they just were not in the budget at that time. Well, we went ahead while the truck was sitting and ordered all the stuff to convert it to a better fuel system, -10 an lines and filter, and 100 lb/hr injector dynamics injectors. I still have not had time to install that stuff yet, but I did find and repair the issue for now.

It turns out when companies say their pumps are e85 compatible they mean the pumps, not the stuff they stick in their with the pumps..... I put one pump on a stock tbi sender, and another on a aeromotive stealth sender. The aeromotive sender came with a length of hard line to the pump, and that held up just fine. I don't know why, but for some reason I used the short rubber hose that came with the pump kit to connect the pump to the stock sender instead of using the e85 rubber hose I had laying there. That failed, as well as the seals for the connectors on both the aeromotive sender and the stock sender. I pulled the fuel filter apart and found it full of rubber material from the failed rubber hose. I did not take any pics of the connectors.

I put e85 hose on the one pump, cleaned the fuel filter and lines and hard wired the pumps. Works great now and the truck is back to 100%. Soon I will be converting it to the new stuff we got and maybe switching to a rear mount tank, since the stock one will be in the way of the roll cage mounts.

[Mattchu60]

Can you give some information about the two sets of lines running into the gas tank? I'm doing an LS swap and trying to figure out how to run dual tanks - i wondered if that one set of lines is how you accomplished that - maybe like a transfer tank line?

[Ofnaman1]

Originally Posted by Mattchu60

Can you give some information about the two sets of lines running into the gas tank? I'm doing an LS swap and trying to figure out how to run dual tanks - i wondered if that one set of lines is how you accomplished that - maybe like a transfer tank line?

I ran both pressure lines to the regulator and just ran one return line back to the tank. You could not do that with two tanks. I think you would have to split the systems, basically having two complete fuel systems. I almost tried that with a friends '79 that we put an fitech system in, but he did not want to spend the extra $ on the stuff to do it. I think you could do it with a '87 tbi switching valve and senders, but I haven't tried it.

[88notchback]

Very Nice Build. Im preparing to do this swap with my 70 C10 and tko600 trans. Did you get away with the dry sump pan and go wet? If so what pan did you use?

Hows you heat exchanger and pump plumbed?

[Ofnaman1]

Originally Posted by 88notchback

Very Nice Build. Im preparing to do this swap with my 70 C10 and tko600 trans. Did you get away with the dry sump pan and go wet? If so what pan did you use?

Hows you heat exchanger and pump plumbed?

Its a dry sump setup. I used the factory oil pan, it cleared better than the ls2's truck pan on the original engine we had in it. The front oil drain does drain onto the front crossmember, but it's not a big deal. I also used the factory oil tank, it fit perfectly between the battery and radiator. I had to cut the battery tray and inner fender down a little bit, but it almost looks factory, which is what I wanted. I did have to cut a hole in the frame for the oil lines to run through, but it is far in front of the suspension and not a load bearing area. I also took the factory oil lines and removed the hoses and drilled and tapped the fittings to fit -12 an line to them. It all works perfectly, and I am very happy with how it turned out. It is not at my work right now or I'd take some photo's for you.

On a side note, I need to update this thread. I've done a lot to it since then... Boyd welding fuel tank, fuel lines, fuel rails and injectors, plus a bunch of other stuff.

[rodstored-72]

ofnaman1,
very nice build!! seems like a very nice score on the drivetrain, I am in the "designing" phase of my next project & was wondering if you might share some insight on your experience so far. I am thinking of a 5.3 ls & 4l60e/6l80e motor & trans setup. i would like to know what mounts you went with? I am leaning towards the dirty dingo mounts? but have heard good things about Tejas trucks(?) mounts as well? also I was wondering what amount of the "electrical" (ECM) are you utilizing?

Again nice build so far! & look foward to seeing future progress...

rodstored-72