my 250 picks
- Thread starter DYNOED250
- Start date
A
Anonymous
Guest
That's a good thing is suppose, ay?!
I was intending on running on PULP neway, seeing that im already used to filling up at the leaded price - there's hardly a difference between leaded and PULP prices neway.
acl flat tops with 200 rods and a heatseeker stage 2 would be decent with pulp though, wouldnt it?
I was intending on running on PULP neway, seeing that im already used to filling up at the leaded price - there's hardly a difference between leaded and PULP prices neway.
acl flat tops with 200 rods and a heatseeker stage 2 would be decent with pulp though, wouldnt it?
A
Anonymous
Guest
true...
i was thinking more along the lines of gettin a cam to match the comp l8r down the track... seeing that its only a stage 2 neway, im prob not gona wana keep it after the build neway as its not a real performer.
The thing is, how do i know what CR the engine will produce? is there any way to predict it? FOr example, if i used acl flat tops, 250 crank with 200 rods, what sorta cam would i need 2 produce a low 10:something CR? Is it possible 2 predict it?
i was thinking more along the lines of gettin a cam to match the comp l8r down the track... seeing that its only a stage 2 neway, im prob not gona wana keep it after the build neway as its not a real performer.
The thing is, how do i know what CR the engine will produce? is there any way to predict it? FOr example, if i used acl flat tops, 250 crank with 200 rods, what sorta cam would i need 2 produce a low 10:something CR? Is it possible 2 predict it?
A
Anonymous
Guest
lol, ur tellin me!
that's y i thought id ask u, cos u'd have more chance of tying 2 figure it out - if possible neway.
i would have had no chance in hell!
that's y i thought id ask u, cos u'd have more chance of tying 2 figure it out - if possible neway.
i would have had no chance in hell!
gravelrash
Well-known member
geez mate you`ve got some shit in that shed of yours...
gravelrash":2h7azuqt said:
Yep, and I just want a 351 and a hot 250 x-flow and Corty in my SHED!
Departing salvo....
The static compression is fixed. Thats perhaps 9.35:1 on a stock 250 cross-flow.
The effective compression is about 7.2:1 or so, with a stock cam.
The dynamic compression is much more difficult. You get one value at crank over with the stater motor, and it varies hot or cold. Then, at maximum power or torque, there is a thing called Brake Effective Mean Pressure, which tells you how much pressure there is in the combustion chamber. From these, you can determine dynamic compression.
The important thing to know is a street engine with a Stage 2 cam and a static compression is more likely to granade due to a 11:1 static compression than something with a Stage 6 race cam and 11:1 static. The more the duration, the higher the static compression you can use. A long duration cam bleads off combustion chamber compression.
The idea is to stick with the stock arrangement, and add compression as you add duration to a the cam.
The only way you can use high compression on a street engine is by
1.camming it up
2.or running an anti-detonation injection system, such as water, water/alcholohol injection.
or 3. By changing the cam postion, either retarding or advancing, untill you get about 190 psi of cranking presure at idle. If it produces 230 psi, you've got the wrong cam timing for the static compression you have.
Hope that helps. Sorry for the rant.
I'll go an hassle someone else. OO6 lookes like he's having fun with bubble wrap...http://fordsix.com/forum/viewtopic.php?t=10299
excute does this mean when you force fed a motor you can go to a bigger duration cam and not have to take 2 much of the static comp example is say i have a stock motor and put a long duration cam i can just add more boost with the stock comp and still run pump fuel. this seems like a win win situation more power from bigger cam and more from boost.
dynoed250 how much does one of these balancers cost? and also what do they help do to the motor?
Thanks Aaron
dynoed250 how much does one of these balancers cost? and also what do they help do to the motor?
Thanks Aaron
xt falcon":pxjj782x said:
If its a race car, the extra cam duration still builds extra power, and still requires a lower compression ratio. Remember, the exhast is a gas driven turbine which allows much more air to get into the engine. On a street car, using a long duration cam to run a higher compression is very bad. Firstly, the turbo will surge like a water hammered gate valve under anything less than full throttle, and will then produce extra boost. Then the rise in boost will be very sudden due to the compressor not spooling in a progressive fasion.
US guy Jim Flynn used to run a wicked 450 hp Pinto 2000 with a turbo in the 70's. He used a 300 degree cam, but still with no more than 7:1 compression and he still couldn't drive it on pump gas or cruise in it.
With a postive displacement super charger like a 4/71 or 6/71 GMC or Eaton or SC14, the cam duration can be increased to allow a higher compression ratio. This is what the Miller cycle engine is all about (Mazda 800 was released with an engine like this), bleeding off combustion pressure. A turbo is a closed circuit, and every thing is tightly related. On a blown engine, theres a little more scope for messing around without blowing things up.
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