Not defensive, your post makes it look like it never happened, " there's no history or record of them" I got 3 e-mails for board members asking why you would post something that. And now your post above says"I'm sure there is history" Which is it? You are not in the loop on this regardless of you calling Trick Flow after I told you about them which is strange to begin with, your like a stocker lol
Guy's, not my fight but we're getting off topic again. Let's please not go down that road. I'm still waiting for an answer to this. Simple yes or no would suffice.
There are advantages to both open and closed chamber engines. In order to actually compare the difference of open vs closed on the Buick 350 we would have to test both styles with the same compression ratio, same head flow etc. I don’t see that happening. Look at the Buick 455. It came from factory with both open and closed chamber heads. The closed chamber versions out perform the open chamber versions. Each aftermarket head for the 455 is also a closed chamber design. If there was an advantage to going to an open chamber head on the 455 then TA and Edelbrock would have been utilizing that design. Chris is flowing and working on my iron heads now.
I find with a closed chamber head it results in shrouding the valves etc losing air flow, there is different Combustion chambers for NA vs Power adder's which had a soft quench area. There is many different thoughts here.
I don't think there is a simple yes or no answer. The closed chamber with quench (zero deck) allows a higher compression with less chance of detonation. The big block Chevy comparison was mentioned earlier. I have some experience with the Ford 400M (Cleveland)build on a Australian Cobra. The American 351 Cleveland 4 barrel closed chamber head has huge ports that are usually filled 25% and raised. The American 2 barrel head has an open chamber and normal sized ports. The Aussie motors used the closed chamber with normal sized ports. The Aussie head allows higher compression with less detonation than the American open chamber and allows more timing and power.
With a power adder that same close chamber can cause detonation, that is where a soft chamber comes in.
Jim, I know the answer is not a simple yes or no. Was asking simple yes or no did he have data. The purpose of a closed chamber is to concentrate the "squeeze" into a smaller space closer to the plug thus limiting chances of detonation. I know that's a gross over simplification. If you are on the compression limit of the fuel you can use this may be important. On a street/strip engine running less than that compression then I would think the airflow would be more of a benefit. I don't do anything other than N/A so can't speak to that end.
No one has ever tried using an iron 350 with a closed chamber design so no of course there is no data of closed vs open. Like I said no one is going to go to the effort of doing a back to back test with the same compression and flow numbers for both open and closed. These heads would not have been used with stock pistons, this cam and head setup was destined for a 3500-8500 RPM NA race engine. It would have needed forged rods and custom pistons for sure. I’m simply testing these heads for fun, it will be interesting. I’m not suggesting anyone spends thousands on iron head modifications now that the alum heads are out. The cool thing is that these iron heads will make my 9.3:1 engine into a pretty stout NA engine even if it is just for some dyno testing. I do not agree that a “quench zone” is only for a high compression engine. One could build a 9:1 engine with a tight quench zone and enjoy the benefits. Or one could build a 14:1 engine with a tight quench zone, the same theory applies. Normally the ideal quench zone is 35-50 thou depending on various factors. 55-75 thou is referred to as “the danger zone” for detonation and over 75 thou is not normally an issue for detonation but naturally aspirated efficiency is down. Under boost there are lots of guys running pistons way in the hole with effectively no quench zone and no issues. Many guys in the 1500-2000 hp range with pistons way in the hole and both open or closed chamber style heads. Under boost it seems far less vital to obtain a tight quench zone.
Was wondering if you had data from any engine make, didn't have to be Buick. I didn't mean quench was only for very high compression engines, only that it may be a benefit to them more. As Jim noted the reduced chance of detonation. At 9:1 you can reduce detonation with more octane. At 16:1 you may not be able to find any fuel that would run the thing. Boost changes everything. Not something I play with that's why I don't have any info on them.
Yes I have reviewed data on lots of engine tests regarding “quench distance” and yes there can be large gains using a closed chamber head vs an open style. Higher HP, more resistance to detonation are commonly found with a closed chamber head .. While other engines seem to be better suited to an open style head so there are a lot of factors. I’ve read many books discussing the advantages and disadvantages of an open vs closed chamber head. But all that theory is just background information until we actually test how the Buick 350 reacts to these closed chamber heads.
This video talks about valve angles, quench NA and power adders etc. https://www.facebook.com/video.php?v=584901332281994
