SpeedTalk Store - Opinion Columns

Is there a limit to head flow

General engine tech -- Drag Racing to Circle Track

Moderator: Team

Is there a limit to head flow

Postby jeffmckc » Fri Jan 18, 2008 2:25 pm

Let me first thank BigJoe, for the help he gave me on the phone a while back, but the more I thought about what he said, the more questions came up, so I thought I would just post a few of them. I am a long time watcher, bought the pipe max program which caused more questions.

Let me set it up you can see my car in this months March HotRod page 50 SB/NA Drag Week Winner

Motor is: a 427 sbc 4.0 by 4.125 flat top 11.3 to 1, 6 inch rod comp stars, callies crank, world block, wet sump, 1050 Pro Systems dom 95 jets.

Heads are done by Curtis at RFD they are 18x's because of the 68 cc chambers to get comp down they have the push rod pinch fixed and flow 360 at .700 and up to .800 on RFD's flow bench.

Comp cam : Part # 12-000-14 SN# K 9849-07

CS 47s special roller
Grind # CS47 4418s/ 4055s R 114 4/7 .900

Gross Valve lift 704 Intake 672 Exhaust

Duration at Tappet @ 020 307 Intake 332 EXhaust

Valve timing open @050 24 BTDC 80 ABDC
close 73 BBDC 31 ATDC

Measured at Installed 114 Intake center line
I E
Duration @50 277 291

Lobe Lift 414 420

114 lobe sep.

Rockers are Crane shaft 1.7 Intake 1.6 Exhaust
It's installed at 110* intake centerline 4/7 swap
38* timing

Car is a 1980 Malibu stock susp, 4.30, gear turbo 400, 5,200 A-1 conv., msd 7 digital, 3050 with driver, Trans brake.2 inch to 2 1/8 into 4 inch collectors 4 inch all the way out. I race open headers.
Has Drag Radials 28 inches tall, would like to stay around 7000 to 7200 Peak HP rpm its has to be on pump gas and drive down the highway 1500 miles in one week , I won this year with a 9.95 @ 134 I just feel its more of a N2O cam with the exhaust lobe and duration

Is there a limit to the head flow you need in a 11.3 to 1 motor (pump gas 210 psi cranking) I limit myself to .700 lift I could run more if it will live. I dont care how it idles, just so it runs at the track.

I am looking for a different cam. I would like to lower my RPM some down to a peak TQ at 5,000 its now at 5800 395 flat to 6400 on a Mustang chassis dyno and peak HP is 7500 462 but is flat to there from 6100. I now launch at 5000 off the brake and shift at 7800 2nd, 7600 third cross at 7500. I know there is more power to be had I think the cam is the problem. I also have some of Curtis's 12-13 degree heads that flow over 420 at .700
so am I better to fit them to what I am doing keeping in mind the comp ratio or what I have, if I need a cam, I need to know which flowing head is better for the 5000 to 7000 RPM I would like to run. I think those are to much head for this motor.

I have bought several (4 - $400.00) "Vodoo cams" this one above being the last of the just trust me, I wont let you know what it is till I get paid ones.

I wont be buying another one of those, Ed Wilson, Curtis and maybe BigJoe will vouch for me not being the nut this post makes me seem, just getting frustrated with this motor and cam stuff. Any question I will be happy to respond to if I can answer, dont have my other flow # from Curtis yet on the 18X's
2007 HotRod Drag Week Winner SB/NA
2012 HotRod Drag Week Winner SS SB/NA
Fastest/Quickest Small Block N/A
Stock Suspension Car on Drag Week since 2007
9.67@ 139 with a 1.42 60' thru the Mufflers Dot tires
Thanks RFD Heads and Intakes
User avatar
jeffmckc
Pro
Pro
 
Posts: 303
Joined: Sun Mar 04, 2007 10:55 am
Location: I am the Man on the Moon

Re: Is there a limit to head flow

Postby CamKing » Fri Jan 18, 2008 5:20 pm

jeffmckc wrote:Is there a limit to the head flow you need

Yes.
Just as you can have too small a port, you can have too big of a port.
If I'm reading your post right, you no longer want to turn your engine 7,800. You now want to limit the RPM to 7,000. Or do you want to make peak power at 7,000?

If you can get me the full flow #'s and choke diameters on both sets of heads, I can tell you which ones would be better for your application.
Mike Jones
Jones Cam Designs
Denver, NC
jonescams@bellsouth.net
http://www.jonescams.com
(704)489-2449
User avatar
CamKing
Guru
Guru
 
Posts: 8342
Joined: Wed Aug 08, 2007 3:05 pm
Location: Denver, NC

Postby jeffmckc » Fri Jan 18, 2008 5:35 pm

Thanks, my only problem with turning 7800 is piston speed, maybe its getting to high for this short block I dont know its my first 4 inch stroke motor, if its not, I am ok with it. I feel what I have now I am not running far enough past peak HP, should I be going about 500 past threw the lights?
2007 HotRod Drag Week Winner SB/NA
2012 HotRod Drag Week Winner SS SB/NA
Fastest/Quickest Small Block N/A
Stock Suspension Car on Drag Week since 2007
9.67@ 139 with a 1.42 60' thru the Mufflers Dot tires
Thanks RFD Heads and Intakes
User avatar
jeffmckc
Pro
Pro
 
Posts: 303
Joined: Sun Mar 04, 2007 10:55 am
Location: I am the Man on the Moon

Postby jmarkaudio » Fri Jan 18, 2008 7:09 pm

With an RPM max around 7000 and a 5200 converter you want a cam more in the 260 degree range @ .050, LSA at or under 110, lift will be up to you as to what he heads/springs will bear and what you want for limitations for reliability. 114 LSA will allow for NOS and give a little better idle, but will not give as much peak at the RPM range you run it in. Up to you to decide. A smaller cam may give a little more ET, being matched to the converter better, however your car will run the fastest with more converter in the RPM range you are now running.
Mark Whitener
http://racingfuelsystems.myfunforum.org
____

Good work isn't cheap and cheap work can't be good.
User avatar
jmarkaudio
Guru
Guru
 
Posts: 4005
Joined: Wed Sep 26, 2007 10:26 am
Location: Florida

Postby jeffmckc » Fri Jan 18, 2008 7:26 pm

Thanks, the motor is a all motor, never spray motor. I dont mind running the motor to 7800. I talked to marv about getting the stall changed, he thinks I may be down on TQ. If I change Cams, I start all over with the converter, so I would like to get the motor done first ,use a engine dyno then get the convertor changed to it.

Am I wrong in the fact I want my peak HP to be in the 7000-7100 range to cross at 7500. If my cam is as far off as I think I might be able to make more power than I do now, and at a lower stall if it makes more TQ and power in that range thus making the car quicker because its on the motor at the right time.

Do I need to turn it this high to make power, or should I be bringing it (curves) down and that will make the converter stall higher and not need as much

I dont have a RPM picked out to run in I wish to make the motor make power, and set the car to that, But piston speed sets the limits as far as RPM goes and how High I can take it.
2007 HotRod Drag Week Winner SB/NA
2012 HotRod Drag Week Winner SS SB/NA
Fastest/Quickest Small Block N/A
Stock Suspension Car on Drag Week since 2007
9.67@ 139 with a 1.42 60' thru the Mufflers Dot tires
Thanks RFD Heads and Intakes
User avatar
jeffmckc
Pro
Pro
 
Posts: 303
Joined: Sun Mar 04, 2007 10:55 am
Location: I am the Man on the Moon

427 for drag racing

Postby bigjoe1 » Fri Jan 18, 2008 8:10 pm

I will not tell you any speed secrets, but when you are running 11.5 to one, it does NOT like 114 centers. I also saw the same rather high RPM that the engine wanted to run the best E T and MPH.( 7800 at the finish line)I can help you, but not for everybody to see on here.I guess you are still skeptical. That is OK.

JOE SHERMAN RACING ENGINES
bigjoe1
Show Guest
Show Guest
 
Posts: 6013
Joined: Thu Aug 24, 2006 7:16 pm
Location: santa ana calif-92703

Postby jeffmckc » Fri Jan 18, 2008 8:22 pm

No Joe no disrespect at all, believe me, I am stuck and If its ok I will call you back, so I can get some direction on this thing, I still have your # Sorry to have dropped out before Life got in my way or a while.

Thanks for the PM I will call!
2007 HotRod Drag Week Winner SB/NA
2012 HotRod Drag Week Winner SS SB/NA
Fastest/Quickest Small Block N/A
Stock Suspension Car on Drag Week since 2007
9.67@ 139 with a 1.42 60' thru the Mufflers Dot tires
Thanks RFD Heads and Intakes
User avatar
jeffmckc
Pro
Pro
 
Posts: 303
Joined: Sun Mar 04, 2007 10:55 am
Location: I am the Man on the Moon

Postby jmarkaudio » Fri Jan 18, 2008 10:36 pm

The reason your power is flat is because of the wide LSA. As Joe said, you need a cam with a narrow LSA, probably 106 to 108. If your peak torque is at 5800, your converter needs to flash at least that amount, you said it only goes to 5200. Try about 6000 to 6200 if you want it to launch and ET better.
Mark Whitener
http://racingfuelsystems.myfunforum.org
____

Good work isn't cheap and cheap work can't be good.
User avatar
jmarkaudio
Guru
Guru
 
Posts: 4005
Joined: Wed Sep 26, 2007 10:26 am
Location: Florida

Postby Ed-vancedEngines » Fri Jan 18, 2008 11:34 pm

Jeff,
Call Joe and get a cam from him. He doesn't grind them but has a very good line of communication with his guy at Comp that does and there are not many people out there who have done so much with so little when it comes to the SB Chevy. Joe Sherman is the man. He could even have one lying around that would fit your bill. He has done it all poor boy style and he has done it all first class.

Without going into long camshaft discussion, To me everything that has been said in this thread about your particualr cam I am pretty much agreement with. That 114 and lower compression could be good in a streeter, but yours is not a streeter.

Now pray tell me how you have 11.30-1 compression with that engine running flat top pistons and have tight enough squish/quench? Are your chambers huge?

Ed
Ed-vancedEngines
 

Postby af2 » Fri Jan 18, 2008 11:46 pm

Ed-vancedEngines wrote:Jeff,


Now pray tell me how you have 11.30-1 compression with that engine running flat top pistons and have tight enough squish/quench? Are your chambers huge?

Ed


I want to know also?
GURU is only a name.
Adam
User avatar
af2
Guru
Guru
 
Posts: 6232
Joined: Sun Jan 28, 2007 4:42 pm
Location: Grass Valley, CA :Northern Foothills

Postby MaxFlow » Sat Jan 19, 2008 3:17 am

His original post says:

"Heads are done by Curtis at RFD they are 18x's because of the 68 cc chambers to get comp down they have the push rod pinch fixed and flow 360 at .700 and up to .800 on RFD's flow bench."


??11.3 : 1
Joe Stalnaker
WV
MaxFlow
Expert
Expert
 
Posts: 798
Joined: Mon Jan 08, 2007 9:47 pm
Location: WV

Postby Ed-vancedEngines » Sat Jan 19, 2008 4:18 am

Jeff,
You running at appx .050 squish/quench? You have aluminum rods?

Ed
Ed-vancedEngines
 

Postby jeffmckc » Sat Jan 19, 2008 8:48 am

4.125 X 4

68cc chamber

-7 Valve reliefs

.045 gasket

gasket dia. 4.125

Deck .000

Compstar Steel H Beam stroker rod

Pipemax and every other thing says 11.32
2007 HotRod Drag Week Winner SB/NA
2012 HotRod Drag Week Winner SS SB/NA
Fastest/Quickest Small Block N/A
Stock Suspension Car on Drag Week since 2007
9.67@ 139 with a 1.42 60' thru the Mufflers Dot tires
Thanks RFD Heads and Intakes
User avatar
jeffmckc
Pro
Pro
 
Posts: 303
Joined: Sun Mar 04, 2007 10:55 am
Location: I am the Man on the Moon

Postby jeffmckc » Sat Jan 19, 2008 9:04 am

Hey Ed, this is one of the things that make the 12-13 castings from Curtis appealing to me (I own the raw castings on his specials page, he can port to match what I do), they are about a 50cc chamber when done, so I could use an inverted dome to drop comp. Which should make some power over my chamber, but in the short talk I have with Curtis I don’t think this motor will turn high enough with the 4 inch stroke to be efficient and maybe I should return to my 3.875 420cid. motor with them. If that’s right then I will just put a cam and intake on this 427 till I have the bucks to put the other one together again with those heads.
Thanks Jeff
2007 HotRod Drag Week Winner SB/NA
2012 HotRod Drag Week Winner SS SB/NA
Fastest/Quickest Small Block N/A
Stock Suspension Car on Drag Week since 2007
9.67@ 139 with a 1.42 60' thru the Mufflers Dot tires
Thanks RFD Heads and Intakes
User avatar
jeffmckc
Pro
Pro
 
Posts: 303
Joined: Sun Mar 04, 2007 10:55 am
Location: I am the Man on the Moon

Postby Jason G » Sat Jan 19, 2008 10:18 am

Jeff,

I currently run a set of ported Brodix 18X heads (ported by me with help/input from Darin Morgan) on my 445 SBC shortblock (4.145 bore x 4.125 stroke). Dart Iron Eagle tall deck block. The heads went 351 @ .700, 359 @ .800 on R-M's bench.

My heads do not have the pushrod pinch fixed ~2.66 CSA.

I originally started with a "typical" big duration ~.700 gross lift cam. I switched to a "different" Camshaft Innovations (Jay Allen) cam and the engine/car has woke up considerably.

I've only been to the chassis dyno and track once with the new cam and have not done ANY tuning (rich) and also have a few car/chassis issues holding it back still. It chassis dynoed at 596 RWHP and has run the below at 3650 lbs raceweight:

1.43 - 60'
6.36 - 1/8th Mile
108 MPH - 1/8th Mile
(~1600' DA)

Best with the old cam and same converter, gear, and ~1800' DA was:

1.54 - 60'
6.72 - 1/8th Mile
104.1 MPH - 1/8th Mile

It had run better with the old cam with a 4.56 gear and lower DA:

1.49 - 60'
6.58 - 1/8th Mile
107 MPH - 1/8th Mile
(~600' DA)

It chassis dynoed at 569 RWHP in the "old" configuration.

After a couple of tries my ATI converter still isn't right and only flashes to 4900 RPM. Peak TQ is flat from 5200-5500 RPM. I also am currently running 4.10 gears with a 28 x 10.5 slick. Needs more gear and converter. Peak power is at 6500 RPM (head limited) and I shifted at 7000 RPM the first outing with the new cam. After that trip to the track, I sent the 1050 HP Dominator carb to Pro-Systems. I also now have RPM datalogging capability to prove to ATI the converter is not doing what I want it to. After I get a baseline with the carb and get some good data the converter is going to SOMEBODY to be adjusted AGAIN.

To make a short story long: There is power on the table with the RIGHT cam. The right cam doesn't have ~.700 lift. I'll leave it at that ;)

What is the current CSA at the pushrod pinch on your heads?

Also, I don't know how your carb is set up, but a 95 jet sounds awefully big for a Pro Systems built carb.

Jason G.
Jason G
Pro
Pro
 
Posts: 228
Joined: Mon Feb 21, 2005 8:56 pm
Location: TX

Next

Return to Engine Tech

Who is online

Users browsing this forum: bigjoe1, Bing [Bot], Exabot [Bot], FC-Pilot, Google [Bot], Joe Kraemer, joedyna98, KnightEngines, Lizardracing, mikerace4, utahvette, Yahoo [Bot] and 44 guests