WHY are heads not as "important" with FI?
I believe heads are money well spent..... I know my 370 N/A while i was breaking it in was no real slouch even at 8.7:1
Like stated above.... boost numbers dont mean crap to me.... thats like the local ricer saying.... "im running 35psi of boost" doesnt mean jake... its the cfm of air that is being pushed into the motor. Also like stated above all boost is, is a restriction of flow and the easier it is for a motor to get air in the more powe rit will make.
Me myslef i would much rather meet my HP goals on 13-14 psi compared to 17-19... easier on the motor in the long run and other parts as well.
When youve spent this much..... whats a lil more...
Kyle
Like stated above.... boost numbers dont mean crap to me.... thats like the local ricer saying.... "im running 35psi of boost" doesnt mean jake... its the cfm of air that is being pushed into the motor. Also like stated above all boost is, is a restriction of flow and the easier it is for a motor to get air in the more powe rit will make.
Me myslef i would much rather meet my HP goals on 13-14 psi compared to 17-19... easier on the motor in the long run and other parts as well.
When youve spent this much..... whats a lil more...
Kyle
Originally Posted by PHIL H
I agree every little bit helps, but i have seen some guys with turbos put on better flowing heads etc and after than not run any faster.
One example is Mike Murrilo (mustang guy) back in 01-02 at the world ford challenge. He torched a hole in his nice ported $$ heads and was gonna be out the rest of the race.. Well he ended up buying a set of stocker TFS heads from the one of the vendors at the race and he cleaned them up a little and had them machine for o-rings that night.. Put them on and had it running at like 4 am and first pass ended up going as fast or faster than he ever went.. 7.8x @ 185 (28x10.5 non w) or something right around that.
I'm not saying that they dont help, becasue they do but i would rather spend my $$ elsewhere.
Just my .02.
Phil
One example is Mike Murrilo (mustang guy) back in 01-02 at the world ford challenge. He torched a hole in his nice ported $$ heads and was gonna be out the rest of the race.. Well he ended up buying a set of stocker TFS heads from the one of the vendors at the race and he cleaned them up a little and had them machine for o-rings that night.. Put them on and had it running at like 4 am and first pass ended up going as fast or faster than he ever went.. 7.8x @ 185 (28x10.5 non w) or something right around that.
I'm not saying that they dont help, becasue they do but i would rather spend my $$ elsewhere.
Just my .02.
Phil
Phil,
Were ALL things equal except for the heads? Same boost level ect.. I find that hard to believe if everything was exactly the same except for the heads.
I want all of you to think about something here. Take a stir stick straw and a big fat Jack in the box straw. Blow through them both one at a time. Your acting as the turbo and that straw is the intake and heads on a car. Put your hand in front of the straw you are blowing through.
There is a little bit of a diference in what's moving more air right?
Your building a lot of pressure in your poor skull blowing through the stir straw right?
Now, go get a garden house, compare it to you Jack in the Box straw.
If you were a small turbo and did not support a lot af air, the stir stick straw might be fine right? Well if you were a big turbo that could move 4-5x the amount of air the small turbo could, you might want the garden house ehh?
Last edited by LIL SS; Aug 22, 2005 at 01:11 AM.
So from what i gather the ONLY thing to care about it work on teh exhaust side of the heads adn the exhaust side of the cam. Being as other wise you may be pushing 20 psi but only 1 of it is gettin to the cylinders meaning that a AWESOME set of heads that is flowing 15 psi adn delivering 10 of it to the cylinder is the same amt of stress on teh motor and the combustion process.
With that in mind does anyone sell heads that have ONLY upgraded exhaust valve. Like alot bigger since ya dont have to worry about gettin the air in there? GL
John
With that in mind does anyone sell heads that have ONLY upgraded exhaust valve. Like alot bigger since ya dont have to worry about gettin the air in there? GL
John
Originally Posted by 99SS-T
So from what i gather the ONLY thing to care about it work on teh exhaust side of the heads adn the exhaust side of the cam. Being as other wise you may be pushing 20 psi but only 1 of it is gettin to the cylinders meaning that a AWESOME set of heads that is flowing 15 psi adn delivering 10 of it to the cylinder is the same amt of stress on teh motor and the combustion process.
With that in mind does anyone sell heads that have ONLY upgraded exhaust valve. Like alot bigger since ya dont have to worry about gettin the air in there? GL
John
With that in mind does anyone sell heads that have ONLY upgraded exhaust valve. Like alot bigger since ya dont have to worry about gettin the air in there? GL
John
Originally Posted by 99SS-T
So from what i gather the ONLY thing to care about it work on teh exhaust side of the heads adn the exhaust side of the cam. Being as other wise you may be pushing 20 psi but only 1 of it is gettin to the cylinders meaning that a AWESOME set of heads that is flowing 15 psi adn delivering 10 of it to the cylinder is the same amt of stress on teh motor and the combustion process.
With that in mind does anyone sell heads that have ONLY upgraded exhaust valve. Like alot bigger since ya dont have to worry about gettin the air in there? GL
John
With that in mind does anyone sell heads that have ONLY upgraded exhaust valve. Like alot bigger since ya dont have to worry about gettin the air in there? GL
John
Intake side and chamber characteristics are still important as far as volume, velocity, swirl, flame propagation and burn rate, etc. are concerned. You don't want to just take your stock heads and hog out the exhaust port.
Call Brian at TEA and let him explain some of the science behind porting heads. To me it is closer to voodoo. The intake port needs to be modified a little differently than a N/A application because the airflow acts differently under pressure when tha intake valve opens. If air doesn't flow correctly, you can get unwanted turbulence (cavatation) around the intake valve and reduce the efficiency due to less than optimum cylinder fills. Using the right size valves plays into it as well. My heads use a 2.02 intake and the stock 1.55 exhaust yet still flow 295-300 cfm on the inake side, and 247-255 on the exhaust side between .550 and .600 lift. My cam, along with the 1.8 rockers has .555 lift on the intake and .563 on the exhaust side. What does all this mean? It means my heads and cam/rocker combination work very well together. A little more lift on the cam would not hurt, but right now it falls in the optimum range for these heads, beyond this lift, the flow flattens out. For a s/c application, you want your exhaust side to flow at least 250 cfm at max lift, but that won't help if your intake side is not flowing well enough to take advantage of the exhaust capabilities. 1Bad2kTA is correct.. Just like a NA engine, a hogged out port is not the way to go. My example of the straw was to show the PSI build a bad intake/head causes. You still want velocity in to the cyl. When the heads flow better, you can get more air socked in to the cyls under less PSI. More air and more fuel, typically means more power.
