Topic: Racing Head Flows Da NUmbers

[Graywolf]

I believe it was BenL that wanted the flows of my ported and chambered head Which was done by West Racing Heads. I do not have data on a stock head but from what I understand  it is pretty darn good.  Most drag cars putting out 1,200 plus hp use the pre2007 Lsj ecotec head.

GM Racing offered this head that they ported and chambered.
Hear are the numbers for that head
-Intake valve 1.4 Exhaust valve 1.2 @ 28 lbs pressure
-Intake- .2 lift 165cfm  .3lift 233cfm .4lift 269cfm .5lift 224cfm  
-Exhaust- .2lift 162cfm .3lift 201cfm .4lift 213cfm .5 220cfm  

Now for flows of my LNF head
-Intake valve 1.4" Exhaust 1.2" @ 28lbs pressure
-Intake .2lift 163cfm .3lift 232cfm .4lift 271cfm .5lift 288cfm  
-Exhaust .2lift 163cfm .3lift 203cfm .4lift 215cfm .5lift 221cfm.

As you can see my flows equaled and even had slightly better peak flows than the Gm racing head.

Please note stock valves are Intake 1.385, Exhaust 1.185   Breathing Great in Coal Valley Illinois

[Ben L]

Nice!

[kennysabarese]

Can anyone 'splain what this means to us normal folk?

[Ben L]

These numbers show how much air (in cubic feet per minute) the heads will flow at various increments of valve lift.  As you know, engines are nothing more than air pumps.  While more is not necessarily always better (if other components cannot accomodate increased airflow, who cares?), comparing relative flow rates at various degrees of lift before and after head work can tell you something about how such work will improve performance and efficiency at various points of the power band.  Also, you cannot make big power unless the heads are able to move big amounts of air through them.  So when building for big hp and torque nos., at some point, the volume of air/gas the valve train and head flows can become a limitation.  I asked Graywolf mainly because I was curious to see how much and at what lift points the head work he had done varied from stock.   

[kennysabarese]

Cool. Does his results show that this is something worth doing for most folks? Or only if you plan on upgrading your turbo?

[Ben L]

My view is that any head can benefit from porting and flowing, but its a major undertaking to pull them.  I think for the most part on production cars heads and intakes are assembled "as cast."  Smoothing out the transitions between the manifolds and head ports (especially exhaust side), shaping the combustion chamber, etc.  done by someone who knows what they are doing is beneficial.  The goal is to eliminate "steps" and rough places that cause turbulence.

For example, when rebuilding the 347 V8 SBF for the FFR coupe over the winter, the engine builder did some mild flow work to the heads and combustion chamber (did NOT port match heads to intake), and we picked up over 25CFM at low lift and 15 at max lift of .60 (solid roller cam, so that's "true" lift).  That translated on the test drive butt dyno to more kick down low, where it needs it, because this motor's happy place is between 4000-7500 rpm.

[wspohn]

Aside from the flow limits of the head, the thing that will limit output on the LNF are the cams.  Until someone comes up with a new set of cams (hard on a VVT engine) to take advantage of the increased flow at higher lifts, you are leaving some power on the table.

[kennysabarese]

How bout these?

https://www.zzperformance.com/cobalt_ion/products1.php?id=1124&catid=143

[Ben L]

I think another serious limit to output on the LNFs is the constriction on the exhaust side of the turbo.  

Will the 'Balt cams work in the LNF?  Are they VVT compatable? 

Wonder if Graywolf researched these in his travels?

[Kelu]

Cobalt SS TurboCharged has LNF engine.

As turbo exhaust side, you mean the turbine side of the turbocharger, right?

[Graywolf]

Thanks DeepBlue for making my post more readable. First of all ,there is no high performance cam available for the Lnf engine. The Cobalt ss Lnf.is the exact same engine. Part of the problem is the fact that we have variable cam sensor timing. Somewhere I had the spec on the cam in my early research and showed them to guys that race funny cars. They said little would be gained by a different cam anyway. Ray Bates who builds those 1400hp monster ecotecs said I would get little return for the money spent on the head.{$5,000] However I was looking for higher rpm and the engine is set up to handle 8,500rpm with extended time on the rev limiter which occurs when driving on a road racing course. Still require tune. Ray said just slapping a Bigger turbo from Garret would net me 600hp without head mods. Stop you must build up the engine to with stand this much hp or it will blow up. The stock head of the LNF is great.

[joshmass]

Now for flows of my LNF head
-Intake valve 1.4" Exhaust 1.2" @ 28lbs pressure
-Intake .2lift 163cfm .3lift 232cfm .4lift 271cfm .5lift 288cfm 
-Exhaust .2lift 163cfm .3lift 203cfm .4lift 215cfm .5lift 221cfm.

Those are some great numbers! I didn't get that much from my hand porting 
Intake = .200 149cfm .300 195cfm .400 220cfm .500 226cfm
Exhaust = .200 139cfm .300 184cfm .400 193cfm .500 202cfm
Just smoothed things out a bit and port matched on the exhaust side though.

[kennysabarese]

 

Please note stock valves are Intake 1.385, Exhaust 1.185   

Hey guys, does anyone have the stock flow numbers? I just got off the phone with Lyndon and he is interested in the flow gain from stock.

[joshmass]

Here are the before and after numbers I have:

Exhaust
.050 = 37.2 > 37.7
.100 = 72.1 > 80.0
.150 = 105.3 > 111.5
.200 = 131.7 > 138.5
.250 = 150.1 > 168.6
.300 = 158.0 > 183.7
.350 = 161.3 > 188.5
.400 = 164.5 > 193.1
.450 = 167.6 > 197.7
.500 = 169.7 > 202.1

Intake:
.050 = 51.9 > 52.6
.100 = 82.1 > 85.2
.150 = 113.2 > 117.6
.200 = 139.8 > 148.7
.250 = 160.1 > 177.3
.300 = 170.3 > 195.0
.350 = 174.2 > 216.0
.400 = 175.2 > 219.9
.450 = 176.1 > 223.8
.500 = 177.1 > 225.8