The power increase benefit is clearly seen on a larger displacement motors (>427) from aftermarket LS7 heads vs ported CNC LS7 heads from various testing sources such as Richard Holdener.

But I have yet to see a scientific apples to apples tests (i.e. same CR) comparing the power difference between these heads (CNC LS7 vs ported aftermarket) on a stock 427 LS7 bottom end. Has such back to back tests been performed?

 

Have you contacted some of the vendors such as AHP or Tony Mamo and inquired about their proprietary aftermarket LS7 heads for comparative data?

In my opinion, there are 2 issues when considering a ported OEM LS7 head or an aftermarket NEW LS7 replacement head:

1. Flow characteristics as you are pointing out in your question.

2. Head durability and reliability, correcting the inherent flaws and machining issues along with materials used in the OEM LS7 head versus various aftermarket NEW LS7 heads that do not have those issues, whether you are looking for max airflow or not. "Fixing" the OEM LS7 head may or may not be a permanent solution to the head issues, as has been discussed quite often on this forum.

 

Its just math and physics....

A stock LS7 head flows 365 ish on the intake thru a 270 cc port

A modified (ported) OEM LS7 head flows in the 390 range typically but the port is now even larger 285 - 290 cc's.....more flow but the efficiency (air speed) is similar

1.35 CFM per cc versus the same 1.35 CFM per cc in the ported head.....more volume of air (higher CFM ) will make more power though.

Now compare that to just my mid-priced Stg 2 version on my LS7 heads.....408 CFM thru a finished port volume thats only 265 cc's ......20 more CFM thru a 20 cc smaller hole than a ported OEM head

Think about the gains in airspeed that creates and air speed is just as important as air volume regarding performance gains.....1.53 CFM per CC a much larger number indicating the efficiency of the heads are far greater.

Its a clean sheet design that is just shaped better and has material added in the right places to keep flow moving in a laminar fashion at a higher rate of speed.....helps to pack the cylinder better for every combustion event

Math and physics.....flow dynamics 101

Porting factory castings will always limit your gains and the biggest issue is you didnt really cure all the geometry issues either.....the other huge perk a clean sheet design offers in an aftermarket casting

Call me and we can discuss this in more detail but I hope the simple math I just laid out above helps you to get a better grasp on the situation your comparing.

There is more to it but than just that but what I laid out covers the bulk of why a really efficient designed aftermarket casting will always outperform an OEM casting assuming the port, chambers, valve jobs etc is a really effective design.

Point is you can buy aftermarket castings that perform worse than stock also.....but with a clean sheet aftermarket head if you invest the time and truly design a better piece you have the potential to vastly improve the CFM per cc .....aka airspeed

The best performing cylinder heads always have both....alot of flow and alot of airspeed

-Tony

 

Tony,
Thanks for taking the time to explain the advantages (from a physics stand point....the "cfm per CC" figure of merit) of your cylinder heads vs going with a stock CNC ported LS7. I've been researching the results from your heads, and one thing is for sure they make great power in all the results I have seen! Very impressive. I will be in touch.

-WGT

 

Love your screen name and love the fact you have been a member on this board as long as you have

Would appreciate the opportunity to help you out

Gimme a call....no pressure.....just want to further explain the benefits of running heads that are this efficient and go over a potential package with you (cam, heads, intake etc.)

The potential these cars have when modded correctly, even mild combos just absolutely rip



Cheers,
Tony

 

Hey. come on Tony. I've been on the CF since 1999...27 years! How come I don't get any love? I even liked one of your posts here.
Oh, wait...
Ok, I get it. I don't have a cool screen name.

 

Hib,

Your a legend on this board....I would be curious who is still posting on this forum that has been on here longer than you!?!

But we have done business already and you already know where to go for all your cylinder head and induction needs 😜

(Plus he has a cooler screen name! )

 

Tony,

I am a newbie, Oct 2007!

Awaiting your ported TB for the C6Z06 I ordered, after memorial day, when Im back!

Jeff

 

I've only been here 26 years, and I am far from a gas flow specialist, but one thing Tony mentions that cannot be overstressed is the importance of port velocity.

 

Y’all are all legends. I’ve been on CF since 2010 as a looker but joined only until I bought my first Vette

 

I have what I jokingly call Tony's stage 1.5 heads. I have the stage 1 heads with bowl blending and couldn't be happier with the results and peace of mind that my heads will not go nuclear on me.

Many thanks Tony 🍻

 

I have Tony Mamo designed AFR 180 64 CC heads when he was the cylinder head guru at AFR on my 78 C3 corvette Gen 1 355 and they are the best flowing, highest velocity aftermarket street cylinder head on the market for their size, even today. Throttle response and mid range torque are unreal............for a Gen 1 355 SBC.

 

Your in luck.....your getting one of the newer versions of that TB that we have been working on for quite some time.

Just finished a CNC program for that particular piece (LS7 bronze blade). Real happy how it came out.

Much like the CNC ported LT throttle bodies I started producing late last year the CNC work is super nice.....very small stepovers (only .010).....could pass for an OEM finish for sure

Takes longer on the CNC machine but the results look so good I dont care about the extra 15 mins it takes per part to have the finish that nice.

Im putting this one in a box today and mailing it to one of our customers....note the missing giant hunk of aluminum that's usually blocking a portion of the TB blade obstructing flow.

You have to know what one of these looks like stock to better appreciate the final shape!



Regards,
Tony