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| Airflow chart of a factory slant six head with mods to come https://slantsix.org/forum/viewtopic.php?t=21361 |
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| Author: | slantzilla [ Mon Jan 15, 2007 8:52 pm ] |
| Post subject: | |
Quote: 230CFM is the biggest I've heard of, and from a reliable source. 240 would be as yet unheard of. You will be doing very well if you can get to 210-220 in only one or a few tries.
IIRC, 225 was only achieved with the use of some pretty special equipment if you are thinking of who I think you are.Happy hogging! Lou I know someone else who is trying to buy one of those "thingies" too. 
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| Author: | DusterIdiot [ Tue Jan 16, 2007 6:39 am ] |
| Post subject: | The mythical roller cam... |
Quote: Good luck with Comp and a roller cam.....
I've actually already been down this road. Comp will grind the profile, but you have to provide a roller blank for them as their slant six blank is meant for the solid lifter cam and has no "meat" to work the roller lobes. Also they will want to austemper the blank which may not work for your purposes/ durability issues. Not to long ago the Cox Bros. offered a very nice machined blank with a .6 base circle for about $1000. The problems with a roller cam and a slant are "hardware" and again durability. You can swap the parts from one of the current magnum engines (roller lifters and paddle guides) into the slant, but like the hydraulic lifter engines you'll also want to provide a "bath" to the cam lobes to keep them well oiled). Durability also becomes an issue as no one has run one on the street for any real length of time, so we aren't so sure about "how soon" you'll be putzing down the boulevard and get stranded. A couple of the drag racers have run them with very nice results. The cam would be great for "blown" applications (lobes are pretty much a maximum open and shut profile), just the price and learning curve are out of the reach of most guys.-D.Idiot Another thing to consider is how often roller cam guys wipe out their oil and distributor gears with the billet cam (hence the need for bronze sacrificial gears). |
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| Author: | james jaggers [ Tue Jan 16, 2007 6:41 pm ] |
| Post subject: | Head flow |
We will be reflowing our head tomorrow. We have ported only one intake and one exhaust. I will post the numbers tomorrow. Remember we are trying 1.71 and a 1.45 first. |
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| Author: | james jaggers [ Wed Jan 17, 2007 4:51 pm ] |
| Post subject: | Modified head flow |
We got 173 cfm out of the exhaust with the 1.45 valve. @ .550 lift On the intake side we only got 189cfm @ .550 lift with a 1.715 valve. We wanted to see if the valve was the restriction or the runner, so we took the valve out and plugged the valve stem up. Can you guess what it flowed? Thats right, 189 cfm. I must say that it is one of the smoothest flowing heads I have ever seen. It has absolutely no reversion what so ever. I guess we will open the intake runner up until we see water passages. |
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| Author: | Tom Drake [ Wed Jan 17, 2007 5:05 pm ] |
| Post subject: | |
James I emailed you a graph with quite a few heads on it - did you get it? From our experience you will gain 80-90% of the flow by working the pocket area under the valve. Once you have maximized that enlarging the running does not really gain enough to be worth it and it actually hurt our low lift numbers.(yes we hit water on a test port) Since we run a mild cam with the turbo we feel the low lift numbers (under .500) are criticial to us. The 230 numbers I believe Lou is referring to are on the chart I sent you. This head had the largest CFM number I have seen or heard of from a slant 6 head but the numbers below .500 were horrible. They were barely above a stock head. The runners on this head had been enlarged to the max and had been repairs numerous times because he kept hitting water. Also note on the chart I emailed you all of ours heads used an intake no larger than 1.76 because every time we went bigger the flow numbers fell off especially below .500. Hope that helps and remember this is only our experience with the heads we have done. Tom |
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| Author: | james jaggers [ Wed Jan 17, 2007 5:12 pm ] |
| Post subject: | |
The #s are the same at .500 on the intake and only fall off 6 cfm on the exhaust. Thanks for the info and I did get your flow charts. By the way what size turbo do guys run? |
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| Author: | Dart270 [ Wed Jan 17, 2007 8:21 pm ] |
| Post subject: | |
Tom, The numbers you are referring to are not the "hit water and reweld" head. The ones I was referring to are from the guy much further away from us.  His low lift #s were not as good as some others, but were decent. Lately, he said he has gotten low lift numbers as good as any I have plotted, and kept the ~230CFM.Lou |
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| Author: | Tom Drake [ Thu Jan 18, 2007 4:11 am ] |
| Post subject: | |
T60-1 on the turbo. Lou - His head is on the graph I sent James. Low lift numbers were down with the 230 number. If he has improved on them I did not receive them. We have a new head that has even better #' under .500 than any head we have had before. That is on the rampage motor and I have not plotted in on the chart to compare. Tom PS - The head I was refering to did show 235+ numbers at its peak but as stated above the low lift numbers were barely bigger than stock. |
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| Author: | Dart270 [ Thu Jan 18, 2007 6:18 am ] |
| Post subject: | |
Thanks for the info and clarification, Tom. Lou |
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| Author: | panic [ Thu Jan 18, 2007 11:46 am ] |
| Post subject: | |
as you know on a naturally aspirated engine if a engine is built efficient it will produce around 2 h.p. per cfm What???? |
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| Author: | 1969ronnie [ Sat Jan 20, 2007 6:42 am ] |
| Post subject: | |
hi, any pics of the ports/bowls on any of these heads? ron |
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| Author: | james jaggers [ Sat Jan 20, 2007 7:34 am ] |
| Post subject: | Ports |
I will post some pictures of the ports on my website in a few days. We are trying another intake valve. We have already flowed a nailhead valve against a tulip and it only helped 1/2 cfm through most of the lifts. |
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| Author: | emsvitil [ Sat Jan 20, 2007 4:00 pm ] |
| Post subject: | |
To make things more complicated, are you going to try varying the valve seat angle? (i.e. 30 vs 45) |
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| Author: | james jaggers [ Sun Jan 21, 2007 6:44 pm ] |
| Post subject: | 45 |
No, the valve seat is at a 45 degree angle. |
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| Author: | james jaggers [ Tue Jan 23, 2007 8:42 pm ] |
| Post subject: | more mods |
The head is done as far as being ported and polished. We are reflowing the head tomorrow. I will be posting pictures of the chambers and the runners. The valve seat is @ 45degrees. 11/32 bronze valve guides and pro flow 1.7150 intake and 1.455 exhaust. I guess the flow at its best will be were I have my cam ground but for turbo specs wich will change the duration and lobe seperation. These pictures will be posted on my website tomorrow evening. I will also re -post the new flow #s at all lifts than give an average. |
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