Flow differences between 2V Pre Xflow and Crossflow head.

[Stumps 384]

I was wondering if anyone knows how much better the crossflow head is compared to the 250 2V head on the pre xflow 250.

 

I would like to figure out how much info can be used on the pre xflow to produce comparable results to a decent xflow.

 

I would guess maybe 15% difference between the iron head XC and XA-XB 2V heads.

 

I know the 2V wouldnt compete with later XE-XF heads.

 

Do the 2V engines respond the same with similar cam profiles as the crossflow does?

 

My 2V engine currently has a 214 cam in it and I'm wondering how much bigger I can go in the cam with the older head.

[Thom 6,716]

I was wondering if anyone knows how much better the crossflow head is compared to the 250 2V head on the pre xflow 250.
 
I would like to figure out how much info can be used on the pre xflow to produce comparable results to a decent xflow.
 
I would guess maybe 15% difference between the iron head XC and XA-XB 2V heads.
 
I know the 2V wouldnt compete with later XE-XF heads.
 
Do the 2V engines respond the same with similar cam profiles as the crossflow does?
 
My 2V engine currently has a 214 cam in it and I'm wondering how much bigger I can go in the cam with the older head.

As far as 6 cylinders go I've always compared pre crossflows to windsors and crossflows to Cleveland's, pre crossflows have a smaller port and velocity is your friend, crossflows have a larger more efficient port that responds better to camshaft changes so they are easier to make power out of than a pre crossflow, if you look up classic inlines from the usa they make an alloy version of our 2v heads, they might be able to refer you to a list of cam specs that work in pre xflow's

[Stumps 384]

Thanks Thom,

 

I have been pouring over the classics inline site trying to make heads or tails of the info there.

 

There is plenty of info in relation to different cam specs, most of the info seems to be based around the 200 cubed six that was common in mustangs.

 

I would assume that taking the info for their 200's and making the specs like cam and carb sizes more aggressive would be the way to go.

 

I'm starting to think maybe a crossy might be a easier way to go, plently of proven combos out there..most seem to be based around a 230 degree cam,4 barrel carb and 6al2 ignition, And they seem to make 250 or more horsepower.

 

Would a 2V pre Xflow with oversized valves, a 230ish cam and 4 barrel(I was thinking a 4180 holley or something similar) with pacemaker headers in to a dual 2.5in system(already on the car) and a 6al2 or something similar make 250hp?

 

With a T5 and 3.73 rear end would it crack 13's or am I dreaming?

 

I appreciate all the info I can get

15 hours ago, Thom said:

 

 

As far as 6 cylinders go I've always compared pre crossflows to windsors and crossflows to Cleveland's, pre crossflows have a smaller port and velocity is your friend, crossflows have a larger more efficient port that responds better to camshaft changes so they are easier to make power out of than a pre crossflow, if you look up classic inlines from the usa they make an alloy version of our 2v heads, they might be able to refer you to a list of cam specs that work in pre xflow's

 

 

It seems to be a fair comparison...the exhaust ports on the 2v head are tiny compared to a crossflow.

 

The inlet seems to be quite large however probably not as effecient as the crossflows however.

 

 

[Stumps 384]

From fordsix forum

 

"XD and XE heads have more potential than XF heads.

In 1980, the advent of the Alloy Cross flow had flow figures by the Ford Motor Company. There was a Modern Motor magazine with a Silver ESP Falcon which had it in there. I was only 10, and haven't seen the article again but it had flow figures.

From memory, the flow drop was only 25 " H20, and it flowed 145 cfm through what I think was the intake with the stock lift cam.


The Aussie 2V, with a high lift cam of about 0.500 thou, could run 175 cfm at 28" H20. Somewhere here, someone did some figures back in the early days after the forum crash of November 2002.

The Cross flow alloy head, has been reported by Ausse7Mains or MarkZE as being up to 240 cfm at 28"H20 when using cut-down 2V 351C valves and some radical high porting by welding the external face of the long turn radius. Unlike the old iron crossflow, the alloy head has little wall thickness at the top of the port to create an ideal port size. It's hard to go any more than 40 mm unless you weld the top, and then fettle away untill you have a port that gives the right combination of airflow and mixture motion.


The general information from a combination of sources such as D i c k Johnstons Brisbane Engine Centre and Modern motor/Wheels Reporter Michael Stahl (Wheels Feb 1987) was that 196 hp is about as much as you can get with a stock XF head and an ADR 37a compliant cam a modified carb. The intake manifold was reworked, but the porting was stock. 1995 Street Machine Kevin Bartlett felt 185 hp was about all the stock XF EFI could hack without lots of porting.

Dynoed250 has about 290 hp from his 1.96" intake X-flow head with an upside down EB MPI intake.

The stock Cleveland 2V heads with 2.04" intakes can do 205 cfm at 28" with 0.5" lift and virtually no work, I'm told, so it sounds possible to exceed that.

The key is TIG welding to raise the roof, and getting a better port shape. If the base of the intake port can be raised like in the 173 Chevies and some of the old Apple Port Pinto engines, then you should make it over the 200 cfm level. Since XF's have the high swirl ports, it looks like its a good idea to remove the shroading ledges, and create an SVO type quench area in the area opposite the incomming intake."

 

Found this, it seems to shed some light on the flow differences, they seem to be very similar on the inlet side, but the 2V struggles on the exhaust side of things.

 

Surely the exhaust port differences wouldnt be huge in terms of overall power given everything else is the same in the real world?

 

[Stumps 384]

https://fordsix.com/threads/air-flow-in-cfm-on-the-two-v-and-xflow-aussie-head.25060/

 

Interesting read

[deankxf 21,470]

5 hours ago, Stumps said:

https://fordsix.com/threads/air-flow-in-cfm-on-the-two-v-and-xflow-aussie-head.25060/

 

Interesting read

it's been said a million times i guess,  but how fast do you want to go?

these days with cops and cameras everywhere, a street car just needs to be responsive and peppy and sound good. 

if it's a race car, start with a better engine would be my thinking.  cost Vs reliability/drivability of a highly strung 250 even a crossflow is very high for lots of work. 

 

your plan of T5 with 3.7 diff gears may not even suit it at 100kmh, 2200rpm in 5th might be a pig if the cam choice doesn't suit those lower revs. 

 

about 30yrs ago i had a mild crossflow XE that used to pull strong to 5500rpm, it was doughy as until about 2500rpm then took off (was terrible with stock auto and 2.92 diff ratio) 
needed a c4 and 2500 high stall and 3.23 diff or a manual and probably still 3.23 gears.. sounded tough, didn't do much else very well (could have been improved on probably with higher compression i assume and better carby setup instead of the stock weber) or .. would have been much much more drivable/enjoyable with an EFI spec cam