Realistic HP for 250 Xflow (XE)

CobraSix

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Myself and Kstang were debating Xflow's versus Mike's AL head.

Not getting into a debate of which is better for which reasons. Was just looking for any head flow numbers, or realistic HP numbers. I know stock they put out around 160BHP, but how are the gains once you do things like a cam upgrade, 351C rockers, etc.
 
I saw recent discussion on the Aussie forum about a recent build that yielded 365 HP N/A at the flywheel, and was given the impression that this kind of power was relatively common for the X-flow engines....at least in Oz anyway. I have seen other discussions mentioning 400 HP N/A as having been achieved previously also.
 
It should be fairly easy to hit 200-225 hp with a very mild 250 Crossflow. Stock they were rated at over 170hp net for most versions and 180 for some of the EFi engines.

My crossflow Mustang was easily doing 0-60 in the 6.5 - 7 second range which is pretty consistent with a ~200 hp engine.

The crossflow Locost is a little harder to estimate because of all the wheelspin. :shock:
 
I remember reading about 190cfm on the intake side for the crossflow, I'll see if I can find that thread. It may have been on xfalcon.com or hotsixes.com, I can't remember.

I am going to aim for 275-300HP flywheel with a 250 crossflow/us block.
Crow 14650 cam
porting to get me around 200cfm @.500" with 1.84 intake valve
full-roller rockers(351C)
AussieSpeed intake
Headers

I havn't built it yet, slowly gathering parts.
 
Well, found these numbers from xrglen's post on xfalcon.
std head,
inlet , 100" 57.3cfm, 200" 98.2cfm, 300" 136.2cfm, 400" 170.2cfm, 500" 196.1cfm, 550" 200.6cfm
300hp head,
inlet , 100" 70.3cfm, 200" 122.9cfm, 300" 168.7cfm, 400" 206.7cfm, 500" 215.5cfm, 550" 205.6cfm

std head,
exhaust, 100" 49.1cfm, 200" 83.8cfm, 300" 112.8cfm, 400" 137.0cfm, 500" 152.5cfm, 550" 159.1
300hp head,
exhaust, 100" 59.6cfm, 200" 95.1cfm, 300" 120.6cfm, 400" 142.0cfm, 500" 154.6cfm, 550" 157.6

the 300hp head is the one he modifies, cleaning up bowls, porting, etc.
 
Glen is a member here, he is who I indirectly bought my head/cam/parts from.

I will probably do the porting myself, I highly doubt my numbers will come out to his.
 
'68falconohio":12ghtaj0 said:
Glen is a member here, he is who I indirectly bought my head/cam/parts from.

I will probably do the porting myself, I highly doubt my numbers will come out to his.

You may want to read up on Glen's recommendations on upgrading and porting the crossflow head.
I believe he installs larger intake valves and doesn't do any porting on the exhaust side.
 
Yeah, I've been reading up on his threads. Been very insightful for boosting the numbers of the crossflow.
 
hi all, i dont do any port work on the 300hp head. it is only a good seat and valve job with attention paid to the bowel area and a reshape of the streamline area around the inlet valve guide boss. i also taper the guide bosses but you need to heat and remove them to do it right. i only port on 300hp+ heads and then there is not much to do but its very important to know where to port. if you take 20" too much from either side of the port you can lose hp. i do slight port work on the exhaust when large solid cams are being used but again this is only on 300hp+ motors. i have had the last 6 months off work due to moving house and a well needed holliday and i will be back in to it soon. i have 3 motors which i will test after easter and they are the 365hp, 400hp and new supercharged motor. they will all be tested in the same car, same dyno and at the same track so results will be more even. i am no longer building a big bore motor to test due to my time being limited with work so the supercharged motor will take its place as aussiespeeds new blower manifold is due out soon. i have a 40" bottom end with forged ross pistons, preped rods and crow solid cam ready to go and i have done an o-ringed xrglen head to suit with bigger exhaust valves and exhaust porting as well. it wont make much more than 350hp but it should have a ton more torque than a N/A x-flow.
if anyone has ant questions i can be contacted by email at mhbs@people.net.au
i will be happy to answer all questions that any fordsix members have..
Cheers
 
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