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Best Heads for SE

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    Default Best Heads for SE

    I'm collecting parts for an eventual SE boat, and been reading the dyno threads and talking a lot with the local engine builders. Given the SE rules, the Vortec head is legal, and one would think the new technology would be a good thing. However, I've learned a few things from GN7 and others that makes me think they would be the wrong way to go, because with the big gasket and the flat top pistons, you do not get an effective quench, which seems incredibly critical to making a good, long running engine.

    So if the Vortecs are not the way to go, does anybody have a line on the best heads to grab? Which ones provide the best quench within the SE rules?

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    Quote Originally Posted by 61 Sanger Ski Hydro View Post
    I'm collecting parts for an eventual SE boat, and been reading the dyno threads and talking a lot with the local engine builders. Given the SE rules, the Vortec head is legal, and one would think the new technology would be a good thing. However, I've learned a few things from GN7 and others that makes me think they would be the wrong way to go, because with the big gasket and the flat top pistons, you do not get an effective quench, which seems incredibly critical to making a good, long running engine.

    So if the Vortecs are not the way to go, does anybody have a line on the best heads to grab? Which ones provide the best quench within the SE rules?
    Illegal non GM heads that have a 76cc chamber and the vortec port, and you grind and polish the ENTIRE exterior, including in side the rocker area, until they are unrecognizable as not being GM heads, and then you have them powder coated, them all you are a blinger. Let them PROVE the port is a "vortec port"

    Think I'm kidding?
    You should see what I would personally REALLY do. It makes that look tame. USING A STOCK GM VORTEC HEAD!!!

    I have a E85 carb in my head that would freek ole Grumpy out!

    BTW if lack of turbulence and quench is a problem with the vortec head, which was DESIGNED to create turbulence and fast burn, but is killed by the lack of quench, then a LONG ROD does not play well in that scenario. It only makes the problem worse.



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    Last edited by gn7; 08-23-2013 at 03:11 PM.

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    Quote Originally Posted by gn7 View Post
    BTW if lack of turbulence and quench is a problem with the vortec head, which was DESIGNED to create turbulence and fast burn, but is killed by the lack of quench, then a LONG ROD does not play well in that scenario. It only makes the problem worse.
    Just to confirm that I read your sarcasm correctly, you are saying that within the rules, with flat-top pistons, you can not get the proper quench with the the vortec head, right? And thus, it should probably be avoided?

    Please forgive my lack of knowledge, but why would a long rod hurt this scenario? I thought the long rods just improved the geometry of how the piston's energy is transferred to the crank.

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    What's the rpm range of these engines? What other heads are considered legal? Is the EQ "IMCA" head legal? What about the World Products head? I don't consider a high swirl port good for racing.
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    Quote Originally Posted by 61 Sanger Ski Hydro View Post
    Just to confirm that I read your sarcasm correctly, you are saying that within the rules, with flat-top pistons, you can not get the proper quench with the the vortec head, right? And thus, it should probably be avoided?

    Please forgive my lack of knowledge, but why would a long rod hurt this scenario? I thought the long rods just improved the geometry of how the piston's energy is transferred to the crank.
    I wasn't being nearly as sarcastic as you might think. Not AT ALL sartcastic about what I would do to a stock vortec head.

    The longer the rod, the slower the piston moves in and out of the head. This does a number of things to this engine.
    It creates less turbulence in the chamber that is ready suffering because you have killed the quench.
    It hangs around on the chamber longer building up pressure in a cylinder that is already detonation prone because of the lack of turbulence.
    The engine is limited to lift, which only leaves you with duration and LSA to play with. With the piston hanging around TDC longer, and leaving slower, your intake timing is either limited, you need larger valve notch to clear the valve, specially the intake. I would order the pistons with no notches and only make them as deep as I had to, and do what ever I had to make them as shallow as possible.
    There may be a negatives to the intake port activity with a slower declining piston and a stock junk port as well. Long rods work great, if you have a well developed intake port to match it. Low lift flow can be critical with a limited lift engine, and the longer rod is hard to develop good low lift flow with the piston leaving the chamber slower than a short rod.



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    Quote Originally Posted by steelcomp View Post
    What's the rpm range of these engines? What other heads are considered legal? Is the EQ "IMCA" head legal? What about the World Products head? I don't consider a high swirl port good for racing.
    Only factory production GM heads.

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    Quote Originally Posted by gn7 View Post
    I wasn't being nearly as sarcastic as you might think. Not AT ALL sartcastic about what I would do to a stock vortec head.

    The longer the rod, the slower the piston moves in and out of the head. This does a number of things to this engine.
    It creates less turbulence in the chamber that is ready suffering because you have killed the quench.
    It hangs around on the chamber longer building up pressure in a cylinder that is already detonation prone because of the lack of turbulence.
    The engine is limited to lift, which only leaves you with duration and LSA to play with. With the piston hanging around TDC longer, and leaving slower, your intake timing is either limited, you need larger valve notch to clear the valve, specially the intake. I would order the pistons with no notches and only make them as deep as I had to, and do what ever I had to make them as shallow as possible.
    There may be a negatives to the intake port activity with a slower declining piston and a stock junk port as well. Long rods work great, if you have a well developed intake port to match it. Low lift flow can be critical with a limited lift engine, and the longer rod is hard to develop good low lift flow with the piston leaving the chamber slower than a short rod.
    Isn't everything you stated about the "long rod" rpm relative? We're talking about piston speed. The Vortec head is not designed for sustained high rpm use, is it? Isn't that why they invented something to induce all that swirl and turbulence? For low speed performance and lower emissions? One thing for sure...creating all that turbulence and swirl on the port side of things takes a lot of energy.
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    Quote Originally Posted by Budweiser View Post
    Only factory production GM heads.
    Gotcha.
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    Quote Originally Posted by gn7 View Post
    I wasn't being nearly as sarcastic as you might think. Not AT ALL sartcastic about what I would do to a stock vortec head.

    The longer the rod, the slower the piston moves in and out of the head. This does a number of things to this engine.
    It creates less turbulence in the chamber that is ready suffering because you have killed the quench.
    It hangs around on the chamber longer building up pressure in a cylinder that is already detonation prone because of the lack of turbulence.
    The engine is limited to lift, which only leaves you with duration and LSA to play with. With the piston hanging around TDC longer, and leaving slower, your intake timing is either limited, you need larger valve notch to clear the valve, specially the intake. I would order the pistons with no notches and only make them as deep as I had to, and do what ever I had to make them as shallow as possible.
    There may be a negatives to the intake port activity with a slower declining piston and a stock junk port as well. Long rods work great, if you have a well developed intake port to match it. Low lift flow can be critical with a limited lift engine, and the longer rod is hard to develop good low lift flow with the piston leaving the chamber slower than a short rod.
    Thank you very much, this is great info! I didn't realize that the long rod changed the speed that the piston moves near TDC/BTDC, had to draw a graph to really visualize it.

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    Quote Originally Posted by steelcomp View Post
    Isn't everything you stated about the "long rod" rpm relative? We're talking about piston speed. The Vortec head is not designed for sustained high rpm use, is it? Isn't that why they invented something to induce all that swirl and turbulence? For low speed performance and lower emissions? One thing for sure...creating all that turbulence and swirl on the port side of things takes a lot of energy.
    Not talking about port swirl or turbulence, cylinder quench/turbulence as the piston ascends.
    The head is not considered a great sustained high RPM head, but the intake port flows well enough better than anything else GM made, that everybody runs after the head because of the intake port flow. But the chamber is a fast burn high turbulence chamber that works GREAT, if you use a .035 quench, not .100. The it become a dentation prone POS.



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    Last edited by gn7; 08-23-2013 at 04:26 PM.

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    Quote Originally Posted by gn7 View Post
    Not talking about port swirl or turbulence, cylinder quench/turbulence as the piston ascends.
    The head is not considered a great sustained high RPM head, but the intake port flows well enough better than anything else GM made, that everybody runs after the head because of the intake port flow. But the chamber is a fast burn high turbulence chamber that works GREAT, if you use a .035 quench, not .100. The it become a dentation prone POS.
    Running this head with less compression than it was designed for could be problematic as well. The chamber has a lot to do with how the intake port behaves. If you think about the chamber as an extension of the port, it's easier to understand. I can pick up lots of flow in a head just by working the chamber. In general, reducing swirl will make more power but these heads are a compromise of trying to make HP, tq and do it over a wide rpm range, on crap 87 pump gas. They also depend on EFI for a lot of what they accomplish and having a spot-on tune. and a well matched cam to boot.
    Last edited by scott foxwell; 08-23-2013 at 05:19 PM.
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    Quote Originally Posted by steelcomp View Post
    Running this head with less compression than it was designed for could be problematic as well. The chamber has a lot to do with how the intake port behaves. If you think about the chamber as an extension of the port, it's easier to understand. I can pick up lots of flow in a head just by working the chamber. In general, reducing swirl will make more power but these heads are a compromise of trying to make HP, tq and do it over a wide rpm range, on crap 87 pump gas. They also depend on EFI for a lot of what they accomplish and having a spot-on tune. and a well matched cam to boot.
    There is the rub in a nut shell. They are a TRUCK head. People for some reason what to look at them as the Vette alumn fast burn head, and THEY ARE DIFFERENT!

    The head NEEDS the quench to function as designed.

    You can't play in the chamber of the head either.

    I have no doubts that the average guy would be better served with a 76cc head that allows for a .040 quench. The IMCA head is available with a 76cc head, with a legal size intake port, but its not "legal"



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    I've learned a lot here, thanks to both of you. Everything you've said makes a lot of sense.

    I've been researching online, but it's hard to sort out all the info. Can anybody recommend a legal head casting with 76cc chambers and some 1.94 valves? Reading around, it seems like a lot of common smog-era heads such as the 882 castings fit the bill, but do any of them have particularly better or worse characteristics?

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    Quote Originally Posted by 61 Sanger Ski Hydro View Post
    I've learned a lot here, thanks to both of you. Everything you've said makes a lot of sense.
    a
    I've been researching online, but it's hard to sort out all the info. Can anybody recommend a legal head casting with 76cc chambers and some 1.94 valves? Reading around, it seems like a lot of common smog-era heads such as the 882 castings fit the bill, but do any of them have particularly better or worse characteristics?
    The 882 is probably the best choice of the 76cc heads.

    I think the vortec can be made to work, but I think a 5.7 or 6.0 rod and working it out with E85 on a dyno for the jetting and TIMING, and RPM range.
    I think one of the problems the vortec headed engines were having was partially due to trying to run them at too low of a RPM thinking it was easier on the engine, but in fact was loading them harder than they should have been. I think they needed to let them run.
    There is no reason those things can't 7000 under the rules.



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