Just got my 6.5 turbo setup some questions for those that have done this before.

remote6 · Dec 3, 2013

So just pulled a turbo and exhaust manifold from a 96 3500. I would like to know what head gasket people would recommend, do you get the .10 over 6.2 gasket or go with the 6.5 gasket? I was looking on the interweb and is the stock gasket rubber? Ive also seen copper and steel gaskets whats the best meterial? I know most people go with the head studs but I dont realy have the funds to pay for arps its like 180$ any other head stud options or good head bolts? I will be keeping the stock ip it was rebuilt and I will be turning up the fuel. How about the injectors a couple of mine are leaking so I think I need to replace them anyways. Should I use the 6.2 injectors or the 6.5 injectors.

Any info or suggestions would be great,

thanks Joe

twomorestrokes · Dec 7, 2013

There are plenty of build threads here that will answer all of your questions. I have one and there are quite a few others. Just double up the exhaust manifold gaskets on the turbo side. 6.2 and 6.5 gaskets are the same.

muddobber40 · Dec 8, 2013

If you are swapping head gaskets, go with the .10 thicker gaskets. I prefer Fel-Pro over Victor. I generally get them from rock auto along with head bolts. Head studs are not necessary if you keep your boost down. I have done plenty of 6.5 turbo swaps, in fact I did three last month, and have done most using the factory head gaskets. The 96 should have the GM 5 turbo with the vertical waste gate actuator. I have found with this style you can hook the vacuum line up from the vacuum pump and boost peaks around 10 psi. I have only had a few where I needed to build a mechanical waste gate actuator. Peak boost will also depend on how much your pump is turned up and where your timing is.

The 6.2 injectors work fine. I have never had any interference issues . If you do swap them for the 6.5 injectors, you will need to get the lines as well. You could bend the lines if you really wanted, but they don't run too much for a used set. You also do not need to swap both manifolds, or use any type of manifold gasket.. Unless your truck is lifted the stock crossover will not fit with enough driveshaft clearance anyways. If you didn't grab the passenger valve cover and CDR valve, you will have to re plumb the factory CDR valve hoses. It is cleaner to use the 6.5 set up, but isn't too hard to make the factory set up work.

Did you grab the turbo oil return line and plate at the block?

twomorestrokes · Dec 8, 2013

muddobber40 said:
You also do not need to swap both manifolds, or use any type of manifold gasket.. Unless your truck is lifted the stock crossover will not fit with enough driveshaft clearance anyways. If you didn't grab the passenger valve cover and CDR valve, you will have to re plumb the factory CDR valve hoses. It is cleaner to use the 6.5 set up, but isn't too hard to make the factory set up work.

True, you CAN use the factory 6.2 left manifold but it is quite a bit smaller outlet diameter than the 6.5 manifold, which is why I decided to go with both manifolds. Good point on the front driveshaft clearance. My truck IS lifted so stock crossover works well. Made it easy not having to fab up a crossover pipe. Stock 6.2 CDR valve and hose to the filler neck worked fine in original location, just had to hook to the intake nipple at front of turbo. Some folks hook the CDR to the ehaust, downstream of the turbo using a crankcase evac valve like the racers use. I may switch over to this type of venting as the exhaust I am going to install has a fitting already welded in for a valve. (system was custom made by another member who now uses a Cummins in his truck)

remote6 · Dec 11, 2013

twomorestrokes said:
True, you CAN use the factory 6.2 left manifold but it is quite a bit smaller outlet diameter than the 6.5 manifold, which is why I decided to go with both manifolds. Good point on the front driveshaft clearance. My truck IS lifted so stock crossover works well. Made it easy not having to fab up a crossover pipe. Stock 6.2 CDR valve and hose to the filler neck worked fine in original location, just had to hook to the intake nipple at front of turbo. Some folks hook the CDR to the ehaust, downstream of the turbo using a crankcase evac valve like the racers use. I may switch over to this type of venting as the exhaust I am going to install has a fitting already welded in for a valve. (system was custom made by another member who now uses a Cummins in his truck)

'Thanks I did read your post, I think about your turbo setup just wanted to get a little more info like gaskets people are using and all. I wanted to use both manifolds but striped the first bolt on the driver side and did not have the tools on hand so will use stock 6.2 and make a cross over.

remote6 · Dec 11, 2013

muddobber40 said:
If you are swapping head gaskets, go with the .10 thicker gaskets. I prefer Fel-Pro over Victor. I generally get them from rock auto along with head bolts. Head studs are not necessary if you keep your boost down. I have done plenty of 6.5 turbo swaps, in fact I did three last month, and have done most using the factory head gaskets. The 96 should have the GM 5 turbo with the vertical waste gate actuator. I have found with this style you can hook the vacuum line up from the vacuum pump and boost peaks around 10 psi. I have only had a few where I needed to build a mechanical waste gate actuator. Peak boost will also depend on how much your pump is turned up and where your timing is.

The 6.2 injectors work fine. I have never had any interference issues . If you do swap them for the 6.5 injectors, you will need to get the lines as well. You could bend the lines if you really wanted, but they don't run too much for a used set. You also do not need to swap both manifolds, or use any type of manifold gasket.. Unless your truck is lifted the stock crossover will not fit with enough driveshaft clearance anyways. If you didn't grab the passenger valve cover and CDR valve, you will have to re plumb the factory CDR valve hoses. It is cleaner to use the 6.5 set up, but isn't too hard to make the factory set up work.

Did you grab the turbo oil return line and plate at the block?

If I use head bolts can I push 15psi safely and will the vacuum pump support this with the pump turned up a quarter turn. Also I did not know these trucks had a vacuum pump is it on the back of the intake manifold? I seen something there and don't know what it is.

muddobber40 · Dec 11, 2013

In general, just turning the pump up 1/4 turn doesn't supply enough fuel to really notice a difference in power between 10 and 15 psi. from my experience, and I am sure others may chime in with theirs, power seems to peak at around 12 psi. Anything above doesn't seem to make any difference, plus its pushing the GM turbo's and the engines limits. Even with the thicker gaskets its only dropping about .5 on compression if I remember correctly. IF you're looking for reliable power, stick with 8-10 psi. How much you have to turn your pump up just depends on your over all condition of the pump, injectors, timing, engine condition, and altitude. Tis just something you're going to have to play with and fine tune. Tis not all about boost, need to keep an eye on EGT's as well. GM series turbos are not huge air movers so even if your at 15 psi, the flow could be inadequate making your EGT's sky rocket if your dumping too much fuel

With the vacuum pump hooked up to the waste gate it can hold 13 pounds easy and spikes to 15. The pump is behind the intake where a distributor would be on the older GM small or big blocks

So i guess long story short, no 15 psi isn't really safe..not for long periods anyways

remote6 · Dec 11, 2013

Alright I have another question if I should only push 10-12 psi should I even bother changing out the head gaskets or should I save a lot of time and a lil bit of money and just slap the turbo on?

muddobber40 · Dec 12, 2013

You should be fine. Like I said, I have done many leaving the factory gaskets in. Just remember, and I tell all my customers this when I do swaps, these gaskets are going on almost 30 years. They may last the rest of the engines life or fail tomorrow. IF you know you are going to abuse it and push limits, just change them. Also, higher boost just doesn't affect head gaskets, its hard on the lower end. High boost can also lead to engine oil leaks too if your rings can't hold the extra pressure or valves don't seal properly. mainly rear main issues

Just got my 6.5 turbo setup some questions for those that have done this before.

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