gas research & cam suggestion in 250xflow manual cortina

[Anonymous]

Ok Iam looking for some suggestions. I have a TE cortina with a 250 crossflow running a gas research setup, with the standard 4 speed manual and a 2.77lsd diff. The motor apparently has 10:1 compression, thats what I was told when I had the motor rebuilt. Going by the part number I found out that apparently I have 20.5cc pistons. The cam is a crow cam 14771. Motor wise it is a stocker from a ZK Fairlane EFI model (has the alloy head). The dizzy has yet to be recurbed, will this make much of a difference? Iam thinking of getting a gas research vodoo cam, stage 3 or 4. Has anyone used one of these on a straight gas 250? Are they good, or will it be better to get a cam elsewhere? The car has been dynoed and produced 101rwhp. Forgot to mention the manifold is the standard ford 2 barrel job, with a 90 degree bend adapter to the gas carby. Any suggestions welcome. Also has anyone used the ultraflow manifold, did it make much of a difference?

 

[Anonymous]

The GRA cams seem to be a bit peakier than the Crow LPG cam, but thats easily rectified by putting in a different diff ratio.

Thinking about it, this car would be an excellent candidate for a turbo.. I'm assuming the head has been milled to get the CR up, just grab another head to drop the compression and run a low boost of like 8-10 pounds

 

[Fingers]

I would suggest trying a manifold from an EFI XE-XF, the GRA mixer should bolt straight up to it, and the bunch of bananas should give a pretty good amount of torque.
What do you think XECUTE?

 

[xctasy]

I've had 40 000 km's of torque twisting fun with my LPG Falc, and the added torque from the right system with a cam thats not too big is the most gratifing thing around.

CAM:The GRA cams have been optimised for the best BSFC(Brake specific fuel consumption) with a set of Speco-thomas or wade grinds just tested with a barby bottle, and the hp verses fuel consumption figures rated. Leigh then taylored the cam selection from the dyno runs. The Spences Crow cams are technically superior, but the cam cannot be too aggressive on the exhast, or the lightweight fuel air mix just gets pushed out the exhast. If it's a gas-spec cam, it should be fine whatever the brand.

CARB INTAKE:Without getting to spacey, I think the Weber ADM stock intake is passable, even with the nasty 90 degree turn the GRA adaptor has. The issue with the EFI intake is it's huge intake runner volume. On a gas engine, it can cause lift-off throttle backfires. The ignition advance is fine as it is for the std auto 4.1 XE.

There is nothing wrong with the stock carby intake, although it doesn't look to sexy, it sure isn't exxxy.

EFI INTAKE:In an EFI setup, I'm not sure the distribution is as even with the GRA mixer. The torque should be better, but in on-off throttle conditions, you would find the ignition would have to be retarded. The designer of the GRA carb says that the most difficult thing with an LPG installation is that if you advance it, hp grows, but on lift off, it lean backfires or detonates back up the intake tract. So it's a damned if you do/damned if you don't, with no set-up being ideal.

TURBO:A hairdrier is a great idea. For 'bang-for-the-buck', it's a natural.

 

[Anonymous]

Ok guys thanks for your suggestions. I have thought of turboing the car but this isnt a cheap option, looking at around $1200 just for the turbo manifold. Ok I also forgot to mention I also have pacemaker extractors fitted, and have recently had the exhaust redone 2 1/4 sports system. Originally when I fitted the gas research I had the EFI manifold on but decided to change it because of the pod filter I have sucking to much heat from the extractors. The filer in now behind the light where the pollution canister usually sits. As for the suggestion on changing the diff I dont really want to do that as I have had it recoed at the beggining of the year. I made a big mistake, I happened to get another cortina that had a 5 speed in it, which I was told was a supra gearbox, I put it in but the car was revving to much and I was having to changing gears very quick, which was ok in the beggining but that soon became a pain. So I decided to change the diff ratio from 2.92 to 2.77, which helped a little, meanwhile not long after doing that I found out it was actually a celica 5 speed which explains why it was revving so much. Anyway the gearbox didnt last long, started to make nasty noises, so decided to replace it with a factory item. Ideally a 3.23 diff would be better, as it would give better take off but wouldnt rev too much with the factory gearbox. Oh well you learn from your mistakes. Once again thanks 4 your input guys.

 

[Anonymous]

i was quoted 750 for eqal lenghth cast job manifold.

do it the cheap way . get the original cast manifold. angle grind the collector fange of , make sure the cut is straight. then get a new flange to suit your choice turbo( $70) TIG welded in placee of original flange. then grind the inside a bit to match the flange to manifold. :idea:

cheap simple effective, hmmmmm why didn't i think of it for mine...

oh thats right ohc manifolds are two piece piles of shite.