200 CFM Research

[106-1194218389]

[200cfm]

Stude guide valve is 11/32 inside and .562" diameter or 9/16 by 2 5/8 length. Old Cadi TRW # G 745 use to be a replacement.

There is a water cavity between the intake and exhaust and material is ruffly .100 on each side. Should have the cut chamber back by next weekend. Will see what it offers before I attempt a port change. 1.900" would be larger than the above 51% intake to bore rule but on another statement he says try to get the biggest valve possible into the chamber.

[106-1194218389]

[106-1194218389]

Well I have been reading too much lately I guess :;): I have found another very good article on cylinder heads More and More is revealed to us as we read and put it together in our minds.

John

[200cfm]

Another good read article. Here are the speeds on the cut port base line using the PTS pitot

PRt @ .450" lift

290 305 318
297 306 338
279 298 338


SSR (mid apex) @ 315, lower on left side and over 380 on far side of SSR

CFM rather weak at

.100 56.4
.200 93.7
.300 118.4
.350 129.5
.400 137.4
.450 141

[200cfm]

Another good read article. Here are the speeds on the above cut port base line using the new PTS pitot. Haven't figured out how they are measuring the throat velocity. Is that a math calculation or actual pitot. Wonder if they are blowing through the port and measuring the throat via the chamber entrance? And on that average speed, is that the summing of just down the middle or summing of entrance, PRt, and SSR? If you map the entrance port, how far in. 1/4", 1/2", 1", ? Don't understand the term instanteous velocity.

PRt @ .450" lift

290 305 318
297 306 338
279 298 338


SSR (mid apex) @ 315 fps, lower on left side and over 380 on far side of SSR

CFM

.100 56.4
.200 93.7
.300 118.4
.350 129.5
.400 137.4
.450 141
.500 146.1

This is on intake valve of 1.655 and throat measured in at 1.490" on single 45 seat.

[106-1194218389]

Tom,
Refresh me on what the intake port on your head is like? It has been a few years, as in at least 30 since I have worked on one. I remember that the intake port may have been similar to a Chevy Vortec. Is there a ramp in one side to give some swirl to the flow? If there is that may be where the velocity is coming from. In my thinking I feel you would want to even the velocity in the port as much as possible. Also you want to move the "choke" as close to the throat under the valve seat as possible. In an ideal port the choke would be the throat under the valve seat. Depending on who you talk to and what the application is that throat area would be between 88% and 92% of the valve area. With that in mind just remember you are stuck with what you have and it is what it is. You try to get the port as close to the perfect port as you can while remembering there is water waiting for you to grind into. You will only be able to get so close and then disaster. You are doing the right thing in sacrificing a head to the porting Gods. A lot to learn there. It is very frustrating to ruin a good head but just as bad is to have 200 hours in a head just to have to start over again.

John

[106-1194218389]

I also found this discussion going on over at the Speed Talk forum:
"torque wrote:
what rate would port volume increase valve throat < port face 6" long
splayed chev drag race 10300 rpm 450cfm 2.25 valve 91% throat calc total port volume



With port opening at 97% to 98% of valve diameter and runner length at 10.5" total I would have the opening in the plenum at 2.650 diameter for an automatic and 2.700 for a stick car. You might find it wants a 10.250 runner for a stick car but they get really touchy with low end carb signal with that short of a runner length.
__
Darin Morgan
R&D / Product Development Manager
Profiler Performance Products
937-846-1333
682-559-0321
dmorgan@profilerperformance.com

[url=http://www.darinmorgan.com"]http://www.darinmorgan.com"[/url]

You can follow this thread at You may have to join to get access to that thread, but it is free to join. Just keep in mind what RPM this is being used for. It just gives you an idea of trends. This is where Larry Meaux's PipeMax really comes in handy.

John

[Otto]

you may want to drop to a 5/16 stem or 7mm 1.840 with a steeper (higher) tulip shape being a pressurized induction system which may smooth and increase low to mid lift charge direction.. just a thought...

[106-1194218389]

Here is another great help to us who have no money I am pretty sure it has been on the forum before but to save all of us following this thread the time I will repost it - and also they have a gallery of port molds online - I just checked and at this time it will not display - there are some good helps at their web site that are right in line with what we are trying to do - I have done this and it is very interesting also, it helped me pick up on where the trubulance was in my port - Here is another thing that I have discussed with some of you when I was doing my heads. I needed to make the port considerably bigger at the pushrod pinch and here is one approach to it - I hope these will help and enlighten you.

John

[200cfm]

Yes, those were good readings, thanks. My single chamber head is not ready yet. Will try a tulip valve in it to see how it behaves.

Here is what I hope will be the fall close out motor. Been working on it since April. Block is a 55 casting bored from 3.652 to 3.680 or nearly 1/8.




View of the cylinder walls






View of the heavy metal requied to balance the stroker. Fully balanced to the rods and pistons by Performance Counts.



Test fit of the crank. Stude cranks are steel forged. This one is an Avanti crank taken from 3.625 out to 3.875 or 1/4" One of ever so few ever made.



Roller cam, from a salt racer who needed more power. One of a ever so few made. Hope I can get it to work in the quarter.

[200cfm]

Got the cam lubed, installed and marks lined up.





Here is the piston. Using old stock Seal Power Ford Forged 6 cylinder piston, standard size @ 3.680" with Hastings Moly rings. These pistons were lighter than the old stock stude TRW pistons I was using in the 298 motor that pulled the # 1 rod apart this summer. Sooo, hoping the lighter piston weight will keep the current factory rod on the safe side for the same rpm



Got the pistons and pan installed. Modiified the pan by adding a front extension to give full 7 quarts capacity. Test measurements showed 6 quarts would keep the oil lower from the crank so will limit max fill to 6 quarts. Hoping this will solve the oil suction drop on the oil pressure on 60 ft launch.
This was my first oil pan mod and made the mistake of welding it off the block instead of bracing it on a junk block for pan rail support. But that's how one learns.



This coming week the heads will go on the Turbo 200 bench for some flow improvement and PTS pitot mapping. Hoping to get 170 to 175 cfm @ .500. Larry M. sent me a backup Pipemax 3.6 for the new Vista home computer so will be using Pipemax along with engine designer for the heads. Hoping for 300 hp plus on carb and 400 plus on boost.

[49-1183904562]

Tom,

Can you post your Stroke, head CC, static compression, cam timming information gross and at .050 etc. I would like to enter your combo into a couple of my Dyno simulation programs to see what it looks like. Also are you installing the cam streight up or altering it's timming.

Rick

[200cfm]

Ok, bore @ 3.680 and stroke @ 3.875. Chambers are around 60 cc, will have to measure to be sure. Static compression should be around 10:1 with .045" head gasket. Now the cam as best I can determine started as a 252 intake @ .050" and 244 exhaust @ .050" lifter. That gave a 14/58 55/10 at .522 lift with 112 LSA and 24 degree overlap. BUT, the salt racer put a 8 degree retard grind on it. Sent it to a fellow racer who degreeed it straight up and got: intake 5/66 exhaust 45/19.5 with 120 ICL.

To make it respond for the quarter I have installed a 6 degree advance keyway in the cam gear portion and according to Pipemax this offers:

11.5/60.5 / 51.5 /12.5 with 114.5 ICL and 109.5 ECL, net retard @ 2.50 and 24 degree overlap. Still 252/244 @ .050 lifter reference. I will test fire and run it with the above 6 degree advance. Not fully pleased with the profile but stuck with the parameters for now. The dynamic compression is not that high because of the late IVC.

Thanks.

[106-1194218389]

Tom,
Do turbo applications like the cam retarded? I know in N/A SBC we usually run the cam a little advanced. Just wondering.
John