Truck intake w/ 4 bolt TB, 2005 Trailblazer 5.3
10-29-2021, 12:33 PM
#21
From what i can piece together, this would have been the LH6 and probably it's aluminium block counterpart the LY5.
https://www.onallcylinders.com/2019/...ads-cam-specs/
These also had the better 799/243 heads and an AFM version of the L33 cam: https://www.bishopenginereplacementp...25_p_2243.html but without VVT.
So it likely benefited from the 87mm, and was probably a matter of changing an insert in the mold tooling, rather than a whole new mold tool. Meanwhile, not having to change the fuel system.
But when they introduced the VVT, they stepped up the camshaft durations even more; therefore changing to the TBSS style could net an extra few hp. Plus the original GENIII intake mold tool was probably showing it's age by then, so it was worth retooling, and replacing the fuel rails, injectors, etc.
https://www.onallcylinders.com/2019/...ads-cam-specs/
These also had the better 799/243 heads and an AFM version of the L33 cam: https://www.bishopenginereplacementp...25_p_2243.html but without VVT.
So it likely benefited from the 87mm, and was probably a matter of changing an insert in the mold tooling, rather than a whole new mold tool. Meanwhile, not having to change the fuel system.
But when they introduced the VVT, they stepped up the camshaft durations even more; therefore changing to the TBSS style could net an extra few hp. Plus the original GENIII intake mold tool was probably showing it's age by then, so it was worth retooling, and replacing the fuel rails, injectors, etc.
The similarities and differences you mentioned with the L33 5.3HO have always had me wondering if you could take an LH6, remove all the AFM crap, install an L33 camshaft and new lifters and turn it into a copy cat version of the factory L33 engine which is quite rare to find. Before finding the 6.0 LQ4 that I built, I was looking at doing an L33 for replacement of my factory L59 flex 5.3.
10-29-2021, 12:36 PM
#22
My guess... with the introduction of the gen4 with rectangular port heads that have really good flow numbers... GM had to design a flow matching square port intake (LY6 L79 L92 etc). With the better designed intake it probably took very little tooling to design the cathedral port version (TBSS/NBSS) intakes from the same square port casting.
The only difference between the cathedral and the square port truck intakes (besides the port shape) is the cathedral head fuel rail (bolts) mounts are on the inside of the rails whereas the square port heads fuel rail bolt to the outside of the rails. (It's a quick way to ID square port heads in salvage yards or donor trucks)
The only difference between the cathedral and the square port truck intakes (besides the port shape) is the cathedral head fuel rail (bolts) mounts are on the inside of the rails whereas the square port heads fuel rail bolt to the outside of the rails. (It's a quick way to ID square port heads in salvage yards or donor trucks)
Have to ask though.....do you really ever see a square port head'd vehicle in salvage yards???? I never have yet, they're just too new still. If you have, you have much better yards near you than I do here in Socal.
11-26-2021, 01:58 PM
#24
We know the Gen3 6.0L benefits with the TBSS/NBSS intake swap but most the power gains are after 5000 RPM . My guess is the GM engineers designed that one off GEN3 intake with the larger TB for more power or torque or possibly both compared to the old 3 bolt truck intake. If it didn't check either of those boxes I don't think it would have made it into production. I'm sure it wasn't designed to meet CAFE standards (fuel mileage) with the larger TB. I wouldn't think you'd see much gains with your 5000 RPM limit with the TBSS and stock exhaust manifolds.
If you come across the C5 Corvette fuel tank line... it allows the use of the C5 fuel filter making the TBSS swap plug & play. You'll need to adjust the static "Injector flow rate" in the tune to a progressive flow rate because you will be eliminating the vacuum referenced fuel pressure regulator to the non vacuum C5 Corvette regulator. If you don't have HP Tuners this is another reason (cost wise) with staying with the GEN3 style intake. (If you don't have the vacuum regulator on the gen3 fuel rail disregard changing the IFR in the tune)
Photo of the Corvette regulator and Corvette tank (loop) hose I bought from a member here so I could use my return system with the TBSS.
If you come across the C5 Corvette fuel tank line... it allows the use of the C5 fuel filter making the TBSS swap plug & play. You'll need to adjust the static "Injector flow rate" in the tune to a progressive flow rate because you will be eliminating the vacuum referenced fuel pressure regulator to the non vacuum C5 Corvette regulator. If you don't have HP Tuners this is another reason (cost wise) with staying with the GEN3 style intake. (If you don't have the vacuum regulator on the gen3 fuel rail disregard changing the IFR in the tune)
Photo of the Corvette regulator and Corvette tank (loop) hose I bought from a member here so I could use my return system with the TBSS.
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68Formula (11-26-2021)
11-26-2021, 08:53 PM
#26
If he is DBW, then why wouldn't he just use the 87mm TB that came with that manifold? What's an 90mm/92mm tb going to do for a 87mm intake manifold other than either create turbulence at the mouth of intake, or nothing since its not letting in any more air. Why not save the money and just use the factory one, that matches up?
If someone is DBC, then a larger TB has to be factored into the cost of the overall manifold, but why wouldn't someone save the money where they can if there is no gain to be had?
If someone is DBC, then a larger TB has to be factored into the cost of the overall manifold, but why wouldn't someone save the money where they can if there is no gain to be had?
11-26-2021, 09:24 PM
#27
Good info right there, and yes that rationale for how it came to existence makes sense.
Have to ask though.....do you really ever see a square port head'd vehicle in salvage yards???? I never have yet, they're just too new still. If you have, you have much better yards near you than I do here in Socal.
Have to ask though.....do you really ever see a square port head'd vehicle in salvage yards???? I never have yet, they're just too new still. If you have, you have much better yards near you than I do here in Socal.
What you are saying makes logical sense. If there was no difference or gain, why would the factory have bothered to make the changes to the intake manifold incorporating a larger TB. I may take a swing at this one year old, odd bird manifold on this 6.0. I had been planning to do a TBSS manifold, which I already have, but it wasn't going to happen for a while until I worked out the differences in the fuel system and return line. My Tahoe does have a return line and a vacuum ref regulator. It is a "Z" 5.3 L59 flex fuel 5.3 in it's original life. Hopefully the Gen3 truck intake does not choke down all the flow that the larger 4 bolt TB will take in.
I really don't know what RPM range this thing will push to, but I'm just picturing on the gauge cluster tach where 5000+ is and I rarely ever saw the original 5.3 operating in that range or above, guess I'm just not into hot-rodding the daily. Is there much to be gained by dumping the factory exhaust? Thought I'd read it flows pretty decent for a factory setup?
I really don't know what RPM range this thing will push to, but I'm just picturing on the gauge cluster tach where 5000+ is and I rarely ever saw the original 5.3 operating in that range or above, guess I'm just not into hot-rodding the daily. Is there much to be gained by dumping the factory exhaust? Thought I'd read it flows pretty decent for a factory setup?
You really should reevaluate the TBSS intake. There are plenty of threads for just adding fuel rails and a regulator. Do you think you wouldn't have to figure out fuel rails for that intake too?
11-27-2021, 02:33 AM
#28
100% Redneck
Part Number 25948212
Corvette Recycling
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93Polo (11-27-2021)
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