These are the flow #s on a test set of heads we just did. We wanted a few more shots at it before we let the numbers out, but someone got paraniod, so here you are.

5.4L SOHC PI Heads
Done on a Superflow 600
Test pressure 28"

Intake

Lift stock ported
.200 115.8 139.5
.300 147.3 184
.400 166 234
.500 173.7 236
.600 181 237

Exhaust

Lift stock ported
.200 99.5 114.5
.300 125 152
.400 142 188
.500 159 200
.600 163.7 204.8

We are pretty happy, but think they can be improved a little more.
See you at the races.

 

HI!... Well TIM : Your port/polish job looks a lot better than these guys #'s. This was the flow chart from MUSCLE MUSTANGS & FAST FORDS. NON "P.I" heads ported VS. "P.I heads ported. Their ported #'s are still lower than your stock non ported #'s.



http://www.musclemustangfastfords.co...MMFF_MixMatch/

 

Looks like nice gains. When people compare flow numbers be sure you are comparing apples to apples. Make sure the measurements are taken at the same flow rate. In this case it is stated at 28". The numbers would be different on these same heads if the were done at 24". Just an FYI when you start shopping you need to know what the flow reading was done at.

 

Sounds good to me! thanks for the info tim.

 

Those kind of numbers make me think that porting and polishing our heads is worth it. Were larger valves used?

 

Yes, 1mm oversized stainless valves were used. It also received a five angle valve job. Some people say theres nothing to those, but we have seen a nice increase with them.

Tim
REM

 

1mm on both sides or just the exhaust?

Thanks for the response. Next time I am in Florida I will try to come see your shop.

 

Can you go a little bigger valve then 1mm on the exhaust side Tim?

 

IMO, it is pretty close in there. I don't think you could go any bigger.

 

We've looked at going larger, but, as you can see by elands pic, there isn't a whole lot further to go.

If we can get 500 sets sold, we can have aftermarket sets made. Seems like an awful big number to me though,

 

Looks pretty tight, damn. Good #'s on the flowbench though. Ill try to get some info from the guy doing my port work and compare the #'s.

 

How would a set of ported stock heads compare with a stock set of navigator/cobra heads? How about ported DOHC heads?

Costwise, how does a porting job compare to a DOHC conversion?

Thanks in advance!

 

Going .020 on a cobra motor with forged internals, keeping same compression and porting the stock dohc heads on my 98 yielded a rear hp value of 385. Combo of cubes and port work opened it up big time. 2V heads ported right will give you nice power and the ability to up boost. Concentration to the exhaust side is the important aspect.

 

Tim,
Aren’t the 5 angles really overkill for a street motor? I mean unless you are removing the valves and cleaning carbon buildup off, wouldn’t a 3 angle be more practical long term?

 

Hi Tim
Can you tell me what model year the heads are......there seems to be a difference.
Dale