Anyone know there intake port cc's??? Plenty seem to know there cfm. Just curious how big some of the ports are out there. Last I checked, my Stg 3's intakes were at 280+cc's.
I only know what my intake ports on the heads cc at. Just a hair over 280cc. I run a .250 offset T&D stand rocker set so the pushrod holes were plugged and moved. Bobb Makely did some work on a intake port for me and picked up 40cfm. Turns out, the short turn needed fixed. Current #'s .100- 77 .200- 157 .300- 219 .400- 279 .500- 312 .600- 350 .700- 364 .800- 380 I figure out the cross section air speed but I don't remember where I put the math. It was in the target range of a good head and unless you have a reference to work that number against, it is just a number. Two things I was looking for out of my head was cross section and CFM at high lift. Now I just need to get the power down the track and tune it. I have seen heads flow as good as mine and better but much smaller cross section. THey may be good N/A but Nitrous likes a larger cross section. It's my goal to work my way up to 600+ HP of nitrous....Gotta keep them guys under boost in check.
The heads used to flow better at mid lift until the valves got sunk in them. Too many people have messed with my Stg 3's and they need new seats. They are just about too big to do anything else with them. The exhaust is the biggest problem. The ports are too thin and the motor gets warm fast. Just got done welding up one that broke thru. lucky me. Gotta thank Bobb M., he took the time and fix one of the intakes for me to template the rest off of. Been running better ever since. :TU: I have the correction factor and flow scale reading too from the 600 bench he flowed them on, but I don't know if it really says anymore than what the cfm numbers state.
How about 259.5 cc on the intake and 105.5 cc for the exhaust on a set of Stage IVs I know about. They flowed at : -Lift- In-- Ex-- .100 76 65 .200 147 129 .300 218 180 .400 266 222 .500 321 247 .600 362 260 .700 377 264 Cheryl
Stage 4's get a big boost with the move pushrod and straightened port. I got a larger off-set on my rockers and changed my heads to a "Stg 4" style port. Although, the port height and intake valve location seems to be the biggest limiting factor to flow.
I've not been willing to put any more into my heads and have been waiting to see what comes out for our Buicks... More Cylinder head would be great but then you know how it goes......Need more Cam/RPM to take advantage and then you compromise the Engine
Gary, More cylinder would help without more cam or rpm but unless you can get something done cheep, it's best to wait to the money into something better.... Dave, what kind of power have you figured you are making with your motor? How much rpm? Alcohol right? I know you need more cc's to make up for the added space that alcohol displaces. Same goes for nitrous, need to make room for it. Did you ever have a before and after with smaller cylinder heads? It always seems combinations change with the heads and its hard to pin-point differences. With the cylinder heads on my car, the added airflow Bobb found and I finished was the only change that had the car running the same et with 100HP less nitrous. Well, I also added a merge collector that steps from 3 1/2" to 4 1/2" over a standard 4 1/2" style but I wouldn't account that noticeable of a difference to the collector. SO, lets say "85HP" heads, "15HP" collectors just for arguments sakes.
Rick, My Stage 1 SE's flow in the neighborhood of yours up to about 650 lift. Being that the stage 1 are smaller heads what would you think the volume of my heads are? Also what is the disadvantage of high port velocity from a smaller port? Im thinking my car should be very responsive when I get out there.
Rick , its around 900hp , 7600 rpm , alcohol does like the bigger port also 1st stg 4's were around 265cc same short block , 8.0's 8'teens, larger ports 7.90's8'0s. Have you flowed your heads with the manifold, if so what kind of efficiency are you seeing? Anyone? Dave
Flowing with the intake is on my "To-Do" list. I am not expecting much with the TA intake. The port match is good but the port direction doesn't match. I use thick intake gaskets and slotted the intake bolt holes to correct the angles the best I could with the port match but still not where it should be. The intake needs to be 1-2" higher at the plenium for the roof and floor angles to line up between the heads and intake at the mainfold flange. Bobb M has a 440 Indy intake he uses which has a much better alignment and flows better when matched up to a set of heads. I want to say it was within 8 cfm when bolted to the heads. In fact, the 440 Indy intake did better than a $2200 dollar sheet metal intake made for a Buick. The pics of the Tunnel ram are on my other computer so I will have to post them later. My combination seems to find 7600rpm pretty easy. The combination is built for rpm but without the flow, it wouldn't do it. TR, Cory's Stg 3 heads flow with mine thru @.650 also but they are much smaller. They could be between 240-260cc's. Since were talking about just Buick stuff, velocity wont hurt you on a street application ro most race application. You start looking at your cross-section when you get into a power application that displaces you airflow cross section or a high rpm cross-section. In a N/A application, it takes RPM to make HP. To figure port velocity: Measure your port floor and roof with solder add them both together and divide it by 2. = Port Length Take your port cc and divide it by 16.39 to converter cubic centimeters to cubic inches. = Cubic Inches Now take "Port Length" and divide by the "Cubic Inches" which will get you "Average port cross-section" in sq. in. (square inches). Now take your "peak head cfm" and divide it by your port "sq. in." (square inch) and this will give you your "XXXcfm/sq. in". This is your "velocity" of airflow per square inch. The target range is 110cfm/sq in (low side) to 130 cfm/sq in (high side).
Rick Engine Analyzer calculates port velocity based on port length and cc's also, reporting it in ft/sec. My ports have always shown very high velocity using that method. Using your method they are around middle of your target zone. Either way I think you would have a hard time making the port too large (in it's current configuration) as far as velocity goes on a high RPM stroker. Dave
Rick, Thanks for the info 240 and up is what I estimated. That explanation of measuring port velocity is to complex for me to under take, I think I'll have to find a shop to do this for me. I also have a question regarding intake manifolds. Since you touched on that. But I will start a different thread to get your opinion on it :TU:
Stage 1 Street Eliminators (circa 2005) Level 4 Race Port 2.26"intake and 1.755"exhaust valves 11/32" stems Combustion Chambers at 69 cc's Intake At 263cc's Exhaust at 179cc's Closed 145# @ 1.850 Open 340# @ 1.250 Coil bind @ 1.070 Seal to retainer 0.850 Valve Intake Exhaust 0.050 38.70 30.10 0.100 50.20 57.20 0.200 149.40 121.90 0.300 213.60 167.50 0.400 276.00 196.80 0.450 303.00 212.60 0.500 329.50 226.10 0.550 349.30 233.70 0.575 356.50 236.20 0.600 361.60 237.50 As per TA Spec Sheet
