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Dart 180 cc alloy head as cast

General engine tech -- Drag Racing to Circle Track

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steve cowan
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Dart 180 cc alloy head as cast

Post by steve cowan » Tue Sep 03, 2019 5:18 am

going to do some testing on a dart alloy 180cc head straight plug.
i have 5 months before my racing season starts again,hopefully purchase a new dart block and run my 383 rotating assembly,4.030'' bore and on a bit of a budget.
before i take this cylinder head to my machine shop for a valve job and flat mill to 61 cc i thought i would share some test data if any one is interested,comments and questions welcome,i want to make 530-540 hp,11.5:1 comp on pump,howards mild lobe roller cam 241-246 @ 0.050,108 LSA,580'' lift with jesel 1.6 rockers,victor jnr intake,950 hp holley.
180cc dart alloy heads 014.JPG
180cc dart alloy heads 010.JPG
180cc dart alloy heads 009.JPG
dart 180 021.JPG
dart 180 024.JPG
dart 180 026.JPG
180cc dart alloy heads 015.JPG
dart 180 002.JPG
intake runner 177cc poured,chamber 65cc,
port stall at 500'' velocity test at 700'' lift and 28'' depression
intake throat is already at 89% as cast
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Last edited by steve cowan on Tue Sep 03, 2019 5:35 am, edited 1 time in total.
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Re: Dart 180 cc alloy head as cast

Post by steve cowan » Tue Sep 03, 2019 5:33 am

exhaust testing surprised me a bit,a bit of turbulence at 350'' then went quiet right up to 700'',testing with short pipe and no pipe,with pipe it had 380 ft/sec on the cylinder side of roof,these heads already have some bias in them as cast,alot more than my dart 165cc cast iron heads.
in my opinion these alloy heads will require minimum work on the exhaust side as they flow well out of the box.
dart 180 030.JPG
dart 180 022.JPG
180cc dart alloy heads 006.JPG
180cc dart alloy heads 008.JPG
dart 180 031.JPG
dart 180 033.JPG
dart 180 032.JPG
dart 180 034.JPG
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Re: Dart 180 cc alloy head as cast

Post by mag2555 » Tue Sep 03, 2019 6:48 am

I am kind of surprised that a 180 CC head from Dart out of the box can't attain 260 cfm @28" @ .550" lift.

From the photos it looks like the chamber could use a good dose of unshrouding work as I think that is what is forcing the air to shift its path of most efficient flow out of the valve that makes for that peak flow of 254 , then dropping off and then creaping back up some.

I also think you can lower the short turn like .050" from the center of it on over to the Exh valve side but you must maintain the same basic arc.
Conversely you can raise the roof on the common wall side above / around the crown of the short turn to make that runner to roof of the valve bowl area trapezoidal as viewed from the Intake flange.

I can't see why you could not yank a easy 275 cfm out of that Head well before you get it stretched out to any where near it CCing out to 195 .

With all of that said the first thing I would do and the flow test would be to streamline those valve guides a bunch and get every spec of roof width you can out of that work on the common wall side .

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Re: Dart 180 cc alloy head as cast

Post by dfarr67 » Tue Sep 03, 2019 11:17 am

What is the best sbc head you have seen as cast out of the box? What is the best head with minimal port work?

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Re: Dart 180 cc alloy head as cast

Post by mag2555 » Tue Sep 03, 2019 12:17 pm

Best Head as per what cid motor and what rpm range is the way it needs to be looked at.

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Re: Dart 180 cc alloy head as cast

Post by steve cowan » Tue Sep 03, 2019 2:39 pm

dfarr67 wrote:
Tue Sep 03, 2019 11:17 am
What is the best sbc head you have seen as cast out of the box? What is the best head with minimal port work?
[/quote
i have 4 x sets of dart heads
165cc cast iron
early sportsman 2 - 200cc
dart pro 1 alloy 215 cc
dart 180cc alloy
all of these heads went turbulent above 500'' lift
this is at 28'' depression and you can hear it separating in the port,the 165cc heads were 480 plus ft/sec over the SSR.
once i layed SSR down and a proper valve job is done the ports are smoother and quiet,the 165cc head had airspeeds of 430-440 @ 40'' depression on the SSR but sounded smooth.
the other thing i have found is all these heads already have a throat size of 89 % as cast which does not really help much in my opinion.
i have never looked at or owned any other brand of head.
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Re: Dart 180 cc alloy head as cast

Post by steve cowan » Tue Sep 03, 2019 2:49 pm

Mag,
after i get the valve job done i will do a change at a time and report back,i am curious as what will make these heads respond the most.
i think shaping the the SSR down to the throat / bottom cut will pick up straight away and stop the separation,i wouldnt be surprised if there is 20 cfm there and it will bring the air speed down a little as well.
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Re: Dart 180 cc alloy head as cast

Post by Biteme » Tue Sep 03, 2019 10:40 pm

Are these the platinum heads?
The floors of the intake port look nothing like my 14 year old pre platinum.
Flow curve looks the same though.
Opening up the bowl and pushrod pinch got them up to 270, but still stalling. I’ve since layed the short turn back, widened the top of the short turn a bit and flattened the floor some (it was a lot higher on common wall side) but never bothered flowing them.
Dragstrip is my dyno 😜

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Re: Dart 180 cc alloy head as cast

Post by steve cowan » Wed Sep 04, 2019 1:40 am

Biteme wrote:
Tue Sep 03, 2019 10:40 pm
Are these the platinum heads?
The floors of the intake port look nothing like my 14 year old pre platinum.
Flow curve looks the same though.
Opening up the bowl and pushrod pinch got them up to 270, but still stalling. I’ve since layed the short turn back, widened the top of the short turn a bit and flattened the floor some (it was a lot higher on common wall side) but never bothered flowing them.
Dragstrip is my dyno 😜
These are the SHP heads, I always buy heads bare and I think the pro 1 heads did not come bare from summit, I wanted straight plugs as well just for ease of access, I think these heads will clean up well, the only thing is a couple of head bolt holes are gone through on the common wall.
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Re: Dart 180 cc alloy head as cast

Post by randy331 » Thu Nov 14, 2019 10:07 am

steve cowan wrote:
Tue Sep 03, 2019 5:18 am
going to do some testing on a dart alloy 180cc head straight plug.
i have 5 months before my racing season starts again,hopefully purchase a new dart block and run my 383 rotating assembly,4.030'' bore and on a bit of a budget.
before i take this cylinder head to my machine shop for a valve job and flat mill to 61 cc i thought i would share some test data if any one is interested,comments and questions welcome,i want to make 530-540 hp,11.5:1 comp on pump,howards mild lobe roller cam 241-246 @ 0.050,108 LSA,580'' lift with jesel 1.6 rockers,victor jnr intake,950 hp holley.180cc dart alloy heads 014.JPG180cc dart alloy heads 010.JPG180cc dart alloy heads 009.JPGdart 180 021.JPGdart 180 024.JPGdart 180 026.JPG180cc dart alloy heads 015.JPGdart 180 002.JPG
intake runner 177cc poured,chamber 65cc,
port stall at 500'' velocity test at 700'' lift and 28'' depression
intake throat is already at 89% as cast
How is this project coming along ?
How big are your ports now ?
Your power goal of 530-540 is easily within reach.
The SHP heads all stall at around that lift you posted.

One thing,.. on the flat mill,.. if you haven't done that yet don't, and get them angle milled instead. I know it's more money.

Randy

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Re: Dart 180 cc alloy head as cast

Post by Elroy » Thu Nov 14, 2019 10:34 am

viewtopic.php?f=1&t=58354&start=75
check this build may give you some ideas////similar cubic inch and goal///318 CFM threw 205 cc volume///something to chew on

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Re: Dart 180 cc alloy head as cast

Post by steve cowan » Thu Nov 14, 2019 1:32 pm

Randy,
Not a lot to report
New pistons should arrive today as well as another cylinder head I ordered from Summit,been tied up in customs here for over a week.
Going to machine shop Monday, using my 4340 Scat crank and 5.7" rods
New CP pistons thinner ring pack, looking at oil ring tension etc
Going for a Dart little M block.
I am interested in your thoughts on angle milling the heads. :D
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Re: Dart 180 cc alloy head as cast

Post by steve cowan » Thu Nov 14, 2019 1:50 pm

Elroy wrote:
Thu Nov 14, 2019 10:34 am
viewtopic.php?f=1&t=58354&start=75
check this build may give you some ideas////similar cubic inch and goal///318 CFM threw 205 cc volume///something to chew on
[/quote.
Yeah seen that one,
I am looking at trying to keep runner under 200cc,and also 2.02" valve.
I calculated 300 cfm at max piston speed at around 6300-6500rpm.
I would like this engine to peak at 6500 but at the track would need to run it through the lights at 7000 plus.
It's a street car that tows a trailer to the track, 3 hrs plus on highway.
Maybe peak power at 6000-6200 might be more realistic.
Camshaft selection still up in the air at the moment, still a complete mystery to me.
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Re: Dart 180 cc alloy head as cast

Post by randy331 » Thu Nov 14, 2019 5:26 pm

Elroy wrote:
Thu Nov 14, 2019 10:34 am
viewtopic.php?f=1&t=58354&start=75
check this build may give you some ideas////similar cubic inch and goal///318 CFM threw 205 cc volume///something to chew on
Is this a model to copy,... Or how not to do it ??

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Re: Dart 180 cc alloy head as cast

Post by randy331 » Thu Nov 14, 2019 5:46 pm

steve cowan wrote:
Thu Nov 14, 2019 1:32 pm
Randy,
Not a lot to report
New pistons should arrive today as well as another cylinder head I ordered from Summit,been tied up in customs here for over a week.
Going to machine shop Monday, using my 4340 Scat crank and 5.7" rods
New CP pistons thinner ring pack, looking at oil ring tension etc
Going for a Dart little M block.
I am interested in your thoughts on angle milling the heads. :D
You have a PM.

Randy

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