4.8 + L92. Is it possible?
4.8 + L92. Is it possible? I want to be absolutely sure about this subject before I move away from the 4.8 and go out to find a 6.0 engine.
Why cant the l92 heads (that are made for a 4.0 bore) be fitted to a 3.78 bore 4.8 or 5.3?
Is it because the valves might have very little clearance coming down into the cylinder? If that is the case, has anyone tried measuring the clearance and using a thicker head gasket with a 4.0 bore? Or will a 4.0 bore gasket not seal a 3.78 deck? (in sbf world I have used 4.125 gaskets on 4.030 bores)
Or does it have more to do with the valves being partially shrouded by the cylinder walls and effecting flow?
I know most people say it cant be done, but I'd like to know exactly why.
Thanks
Why cant the l92 heads (that are made for a 4.0 bore) be fitted to a 3.78 bore 4.8 or 5.3?
Is it because the valves might have very little clearance coming down into the cylinder? If that is the case, has anyone tried measuring the clearance and using a thicker head gasket with a 4.0 bore? Or will a 4.0 bore gasket not seal a 3.78 deck? (in sbf world I have used 4.125 gaskets on 4.030 bores)
Or does it have more to do with the valves being partially shrouded by the cylinder walls and effecting flow?
I know most people say it cant be done, but I'd like to know exactly why.
Thanks
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The intake valve on the L92 heads will hit the cylinder walls. It will not fit. Also, the L92 head are not made for a 4" bore, they are made for a 4.065" bore. The minimum bore size is 4" although there is still a fair amount of valve shrouding with a 4" bore. If you do get a LQ4 or LQ9 and HAVE to use L92 heads, at least bore the block out to 4.030".
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The intake valve on the L92 heads will hit the cylinder walls. It will not fit. Also, the L92 head are not made for a 4" bore, they are made for a 4.065" bore. The minimum bore size is 4" although there is still a fair amount of valve shrouding with a 4" bore. If you do get a LQ4 or LQ9 and HAVE to use L92 heads, at least bore the block out to 4.030".
Yes, the L92 heads were used on 6.0 L engines like the L76. They appeared on the L76 only a few months before the L92 was released. That does not mean they were designed for the 4" bore. The L92 is basically a sibling of the LS7 head made for the L92/LS3 engines. I'm sure GM also wanted them to fit the 4" bore too, but that was probably secondary consideration.
Sorry, didn't realize this post got any attention. I was under the impression those heads were a good bang for your buck. I found a lq4 short for $550, and refurbished l92 heads for $700. I figured with the right cam and intake it might make over 400-450 at the tires.
Am I too far off?
Am I too far off?
might make over 400-450 at the tires.
If I were you, I'd stick with some milled 243s for less money and used the extra cash you saved over L92 heads for a fast intake. That will make just as much power and be an overall better driver.
You can make that much power on an LQ4, although with a compression in the mid 9s it's going to be a dog down low. That's a good combo for a budget low boost FI setup as the compression is low and the slow lazy ports of the L92 will be overshadowed by the forcing of air into the engine by a turbo or supercharger.
If I were you, I'd stick with some milled 243s for less money and used the extra cash you saved over L92 heads for a fast intake. That will make just as much power and be an overall better driver.
If I were you, I'd stick with some milled 243s for less money and used the extra cash you saved over L92 heads for a fast intake. That will make just as much power and be an overall better driver.
Can 400whp be made easily with a 5.3?
