Ford Forums banner

More from 250 PURSUIT ute

4K views 14 replies 9 participants last post by  Aussie Pete 
#1 ·
Are there any performance mods cheap or otherwise that can be done to these. They seem to have it allready sussed in the intake, head and exhaust area. Any ideas would be appreciated.
 
#2 ·
Actually youll find the heads are the 'weakest' link in the whole package, theres probably upwards of 50kw waiting to be unleashed with a good set of alloy heads.

Top of the range Trickflow or Airflow Reseach would do the trick:dev2: :rm2:
 
#5 ·
As Martin said, new heads are the go. Ditch the factory heads for a pair of AFR 185cc heads. Out of the box these babys make killer torque and hp. Depending on what Tickford did to the lower intake you may want to port that further as the Cobra/Explorer lower is a known restriction in hipo engines, expecially with the extra cubes you have. You may want to go an uprated set of springs in the heads to get some more rpm potential that your bottom end will allow. Naturally a custom cam to match the set would be an ideal finisher.
 
#6 ·
For street car I vote for the Trickflow TrackHeat heads as they provide better mid range through more efficient combustion at high BMEPs. The AFRs flow better at the top end though - however, think of where you rev the engine the most........

Exhaust and UniChip are big movers on the 250 engine. Extractors are super important!
 
#8 ·
Petrol Hamster said:
Have you got any gain figures for either exhaust or unichip for the 250 engine? I'd be interested to have a look...

(Frankly it seems quite arse kicking enough already...?)
I believe headers and exhaust will give approx 18-20kW. Add another 10 or so for unichip.
 
#9 ·
more from 250 Pursuit ute

Mine is 199 rwkw with full Herrod exhaust & unichip tuned by Herrod. I believe ex factory it is about 176rwkw. This was done at about 2000 k's and now the ute has done approx. 13000 k's. It would probably be another 2 or 3 k'ws more now as the motor is run in and going beautifully - my wife says definately!
 
#10 ·
Aussie Pete

I would dispute your claim that the Track Heats give better mid-range than the AFRs. The AFR 185 beats the the TFR heads from .300" intake lift up and all the way through on the exhaust side until .600". Now while the AFR sports a larger intake port volume of 185cc vs 170cc for the TFRs, the TFR intake port is shorter for that volume with a larger cross section. The AFR also wins the exhaust flow with a smaller port at 61 vs 66cc.

Sure flow numbers dont win races but consider the AFRs are fully CNC ported and are regarded to have excellent efficiency. In the only head to head dyno comparo using an identical engine combination where 11 different heads were tested on a 302ci the AFR 185s beat the Twisted Wedge (same as Track heat except with emissions compliance and not as good valvetrain gear) all the way through from 2500rpm on both torque and hp. Other main engine details were GT40 intake, B303 cam, 65mm TB and 70mm Cobra MAF and EEC. Article from Nov 2000 issue of 5.0 Mustang mag.

Now slap the same heads on a bigger ~340ci motor (ie Pursuit 250) and you reckon the TFR heads will beat AFR for midrange?
 
#14 ·
ANAKHA:
Yes, flow is a good indication. However, there are so many other factors that need to be looked at. These include cam phase (one of the reasons TFS have their own camshafts), swirl, valve shrouding, and above all combustion shape.

Swapping ehads from a bottom end to do tests only sets a baseline and compares the heads for THAT combo. It doesn't provide the optimum setup for each head.

Take my engine for example from the XR8. Despite assurances from others I did the calcs and found that peak BMEP existed in the range of 2500-3500 rpm. Now, with the previous compression ratio this was being wasted. Some rough calcs suggested that with the dished piston and optimum valve layout of TFS heads the BMEP could be raised quite significantly without detonation using 98RON. I selected a comp ratio of 10.5:1 which turned out to be spot on as Rob Herrod found that only a few degrees of ignition advance needed removal in the lower rpm range to kill all detonation.

Now, take a small chamber head or one with non-inclined valves (providing less 'hemi' effect and the BMEP must be wound back to prevent detonation. Similarly, injector timing and above all injector shrouding/aim versus intake port will all have drastic effects on torque. The AFR heads with the smaller cross section of intake have more exposure to fuel wetting of the intake walls which adversely affects low speed running.

Hence, and with extensive further information, I stand by TFS as the better street head for engines running in the range up to 3500rpm (most combos). For above this, and if you want best possible top end etc I would agree the AFR seem to be the goods.

My question: where does a street engine spend most of its time?
 
#15 ·
svo302 said:
Well Im running those TFS heads & Im more than positive ill kick his ass!!! a 13.21 1/4 mile time pretty much does it for me.
Damn - you beat me. Mine was 13.23 @ 106mph. Of course my driving sucked bad :hl: - something about wanting to get home that night (MEL-SYD) so the T5 was changing gears nice and slow :evillol: :s6:
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top