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Replacement head for iron crossy

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Distracting myself today i started thinking about the head on the crossie, and the idea of going alloy for better manifold choice.

 

48cc chambers in trusty ironhead.

 

From what i can tell the nearest alloy head with similar chamber size is the d head at 48-51cc depending on what website i read off.

All you guru's out there who know better than me feel free to correct me please, or let me know your ideas.

 

Also does anyone have a link to a calculator to work out hp/torque guestimates?

 

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I thought the D head was similar to the C2/C2A head around the 43cc mark, A stock C1A I measured around 47cc

My CNC C2 with sharp part of the chamber rounded off & EVL valves (have a dished face) was measured at 49cc,

Ported & shaved XD head I brought off Sean/Clevo120Y is 50cc,

Off memory Standard XD/XE/E1 55-57cc, E2 50-52, C1/C1A 48-50cc C2/C2A&D 42-44cc, there's a old thread on here that has chamber CC's listed.

 

Kustom Bitz has a free dyno program I've been playing around with for ages, Runs in Excel. http://kustombitz.com/g/9081/fun-free-stuff.html

There was a thread on here(or XFal) years ago about it. Put in Engine Ci & comp, Cam @50, lift & rpm range.

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Also does anyone have a link to a calculator to work out hp/torque guestimates?

 

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There are a few calculator programs you can buy, but they are complex and need many inputs to even be in the ballpark.

 

As for free online ones, it's too much of an ask to offer these carefully developed programs free to the public.

 

There are some simple ones that you can use and just keep changing the figures to suit your estimate, using VE as a pecentage of peak torque.

 

Most engines, unless highly modified, will pretty much make the same torque at an rpm range that the chosen camshaft will dictate. So if you know the peak torque of your engine standard, and you know when the peak torque rpm of your cam occurs, you can extrapolate from there what the power will be at that rpm and taper it off toward redline.

 

So if you're sitting at about 80% VE at peak torque, and that occurs at say 3500 rpm, you could assume that it will drop to say 50% at a 5000 rpm redline (as the engine runs out of breath). So it's taking smaller gulps but more often.

 

This is assuming that you have an optimal induction system (ie not a peashooter carby)

 

 

 

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Cheers guys,
It was one of the threads on here i found that said the D heads were 48ish.
My iron is 48cc chambers with 8cc dish pistons so to keep similar CR without bumping it too high i want to find a head around there too.





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Gerg, i thought i may be pushing as far as freebie apps etc go, i am more curious than serious about the old girls output.

Running a 500 Holley at the mo so it is a peashooter in comparison to alot of the machines on here.

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With what specs I could find on yours 10.9?:1, 230@50 .553" guessed 2200-5500, 5300 peak on the Kustom Bitz dyno program,

(street head) 245hp@5300rpm 286ft/lb@3200 (Race Head) 270hp@5300 305ft/lb@3500.

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Holry sheet batman! Even as a guestimate i would have been happy with 200. Will take it with a grain of salt however lol.

I have worked CR as 10.8 but was complete guess as to headgasket thickness, and not quite zero deck height.

Main reason to go alloy head is for a decent 4 barrel manifold, however the redline 2barrel one on there at the moment has done the job for a decade. Could get a redline ironhead 4barrel and tidy it up i suppose.

570 street avenger should do the trick until i save for jenvey itbs (unlikely dream haha).

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Could you flip a 2-to 4-barrel adaptor to run a 570 on your existing manifold, with a carby spacer to help with the transition? You could do a bit of throating out and smoothing of the plenum to help turn the corner. Just a suggestion instead of starting from scratch with the manifold

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Thunderhead289 (YouTuber) did this on their Satellite revival. 318 hemi (I think) worked a treat.
That's a 8 or 9 parter across two channels,if you want to see the whole thing, thunderhead289 and junkyard digs worked together on it, it was a 383 big block satellite

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Thought about running an adaptor, have had one a trademe watchlist for months. Just did not think too much about it.
Makes sense though and can easily ream out the holes.
You guys are awesome as usual!!

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Opinions. Spacer on the manifold side of the adapter to create more airspeed (venturi effect), or carb side?


Ordering both spacers and adapter from summit after the wedding. Will mix and match to see what works best.

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Is the adaptor offset to one side (ie the 350 pattern lines up with 2 bolts and 2 barrels on one side)? Or is it centred like the one in that video?

If it's offset, it would be ideal for mounting the primary on the engine side (bowl clearance permitting) so the secondaries get a clear shot at the plenum. Now that you have a spacer under the carby, you could use that extra clearance to make the turn softer. I would mould some epoxy filler into the transition to achieve this.

If it's the centred type, neither mounting direction is better, ie: both primary and secondary barrels get the same sharp turn into the plenum. I would still take advantage of the extra volume given by the spacer to mould a bit of epoxy in there to make it a gentler angle into the plenum.

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I had a list of chamber sizes somewhere on xfalcon, but Ford Man's numbers match my memory. I think you want a C1 or an E2 if you don't want to do chamber work. Your compression is already pretty high and I think a D will make it higher (especially if it needs a skim or has had one).

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I had a list of chamber sizes somewhere on xfalcon, but Ford Man's numbers match my memory. I think you want a C1 or an E2 if you don't want to do chamber work. Your compression is already pretty high and I think a D will make it higher (especially if it needs a skim or has had one).
So...avgas ftw?
Haha
Seriously though thanks for the info, not above doing whatever work is necessary. But i am going to try the adaptor and 4barrel route first.
End goal is still efi itb's. But a lotto win or other windfall will be in order for that to happen.

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