I'm building a 434 using a resleeved ls2 block. The engine will have around 11.6 static compression and I'm planning on running a HR cam with a redline of 7000 rpm.

This will be going into a Chevelle that will be mostly a street car, not a max effort type of build. Most likely I'll have a cam with a max .630 lift. Which head will be better in my application. I know the ls7 heads flow better at higher lift but it looks like the 245 heads flow better at lower lifts where I'd be most of the time. I'm open to other suggestions as well I have a max budget of 3k to spend on heads.

 

https://www.powerperformancenews.com...ls7-head-test/

Make your Own choice!

 

While I can not speak to these two cylinder heads specifically...

I can impart on you the importance of low lift flow rates for a street driven vehicle (IE: a vehicle that is used for more than only quarter mile passes).

Years ago GM released the original VORTEC cylinder heads for the GEN1 small block Chevy. Technology created for the new at the time GEN2 engines (LT1 and LT4).
Great low lift flow as cast (when ported good high lift flow as well).

People would take a 260.00 HP 350.00" engine, swap the camshaft/ lifters/ valve springs/ add a carburetor or 4BBL throttle body and carb intake... BOOM 200.00+ HP just by changing the valve events on stock cylinder heads.
460.00 HP or more at the time was huge! A 1998 LS1 Camaro was only rated at 305.00 HP (made closer to 350.00 HP but still...)

I still own a 1998 350 with these heads (I have massaged the massively to improve high lift flow with out hurting low lift flow). For a little 350, the engine produces an amazing torque curve and produces just under 1HP/ Liter... 557.39 HP @ 6400.00 RPM.

In 2000/ 2001, I would drive around in a 1987 Camaro that looked like a stock IROC-Z but lowered on 2000 Corvette 18' wheels and 13" brakes that sounded like NO stock 1987 camaro (225.00 HP).
With that Vortec engine, I used to smoke all the new Camaros, Vettes, Mustangs, Vipers ETC... Ah, Those were the good old days LMAO!

This was the START of what was about to come in the new GEN3 engines!

Generally speaking the better the low valve lift cylinder head flow, the better the throttle response/ acceleration/ torque curve/ and power production below peak horse power (which is much more fun to drive than an engine that only makes power 1,500.00 RPM before peak horse power occurs).

Look for a cylinder head within your budget that will produce the MOST port velocity with the SMALLEST size ports/ runners available.

My favorite example of this would be what Mr. Tony Mamo has always done with his cylinder heads as well as the AFR (Air Flow Research) cylinder heads.
Great port velocity, great low lift flow, and on top of that great high lift flow as a BONUS for more high RPM horse power as well.

 

Good Article!

Well... with this kindly provided information from "Smokey B", We can clearly see that the "245 Model" significantly out flows the "260 Model" on the exhaust side as well as better low lift intake side flow than the "260 Model".

The 245.00 cc intake runner model (TFS 245) is the clear winner! I find this cylinder head superior to anything AFR (Air Flow Research) currently offers in a similar size intake runner cylinder head.

I would talk to Mr. Tony Mamo and see what he currently offers for your configuration... While I do not know the details. He has his own business now, so i would suspect that his cylinders heads out perform the AFR heads.

I am in shock at the performance of the current AFR heads. TFS has had great comparable heads to AFR for two decades now... BUT this TFS 245 head SPANKS AFR! I am blown away, happy for TFS but blown away!

 

440 is a lot of cubes... and the TFS 260, out of the box, are the worst LS7 heads you can buy.

But, I'd still go LS7 over a cathedral head. That test doesn't show much... just the best cathedral against the worst LS7...

 

Thanks for the link, that's the type of comparison I was looking for.

 

Tony Mamo has some amazing ls7 heads, but unfortunately he's out of my budget.

 

 

Btw, the heads that Tony does with the TFS 260s are not what I'm talking about.

Out of the box, the TFS heads are not great. They can be made to work very well though...

The LS3 stuff is a good option as well. Stock ported from AI or even the GMPP heads are a good value for the money and work well on big cube motors.

The aftermarket AFR 260s, MAST 255s, PRCs, Darts, Brodix, or SPS Haymakers all can easily do 700+ HP at the crank on fewer cubes.

 

 

What the respective cylinder heads flow with their respective intake manifold attached provides a good picture of potential performance. A lot of times the various ported cylinder heads get "equalized" by by the intake manifolds.

For a street car build, the .450 lift lift flow and .500 lift flow numbers are usually the most. Important. At part throttle driving on the street a 434 should make a ton of torque regardless of which heads you choose.

How will the Chevelle be set up? Transmission? Rear gear? Stall?

 

The Chevelle has a gto t56, 9 inch with 3.55

 

I just compared the AFR Mongoose 230/ 245/ and 260 models to the TFS 245 model heads...

The flow rates on the TFS 245 spank all 3 of those AFR heads!

I wrongly assumed the AFR cylinder head you mentioned would prevail... however, NOPE! LOL! We are both wrong on that one!
That reminds me why I usually never ever simply assume anything... Always do the research or mathematics at hand. IT IS WORTH IT!

I really don't know when AFR fell off this much... I am sad, very sad!

 

Yes! and even lower lift flow rates play a larger part on the impact of torque production/ the torque curve. This is what I was discussing above in an earlier post.

"While I can not speak to these two cylinder heads specifically...
I can impart on you the importance of low lift flow rates for a street driven vehicle (IE: a vehicle that is used for more than only quarter mile passes).
Generally speaking the better the low valve lift cylinder head flow, the better the throttle response/ acceleration/ torque curve/ and power production below peak horse power (which is much more fun to drive than an engine that only makes power 1,500.00 RPM before peak horse power occurs).
Look for a cylinder head within your budget that will produce the MOST port velocity with the SMALLEST size ports/ runners available."

I prefer to start looking at even the 0.3000" flow numbers... 0.3000" to 0.5000" flow rates make a HUGE impression one the torque and Mid-range horse power production.
In a perfect world which will never exist... Flow rates from 0.0001" to 1.0000" should be phenomenal! We all know that is not happening.
Once a healthy flow rate between 0.3000" to 0.5000" has been achieve... anything that can improve flow rates from 0.5000" to 0.7000" that does not massively harm the lower lift flow rates would be tremendous for a street driven LSx based engine.

In the most simplistic terms think of a Drag race only LSx based engine as an ON/ OFF switch. Full throttle or no throttle... My race car only has a 0.2500" of accelerator pedal travel to better facilitate this ON/ OFF action.
Low lift flow rates are not nearly as important as the high lift flow rates when the vehicle does nothing put fully accelerate from a stop to full vehicle speed.

 

Ideally... I would be looking at the Holley "LS Hi-Ram EFI" intake manifold for your predicted engine combination.

Base on my own dynamometer testing, It is one of few off the shelf intake manifolds to show any improvement in power other than going to dual 4BBl type port fuel injection hi-rise style or custom intake manifolds.

 

I wouldn't get to hung up on flow numbers.

But LS3 heads... with short runner intakes make a ton of power if you're willing to spin them.

 

​Agreed! Flow numbers are actually pretty low on the list of what matters. They do help provide some information when used correctly. They are pretty worthless comparing data different flow benches. The numbers are mostly worthless unless the intake was bolted on to the head. A good porter can use the information the right way to make improvements to the head and make more power. Most of the time flow numbers get used as marketing propaganda.

The brave spinning the LS3 head definitely make the power!
​​​​​​
GTO T56 1st gear is 2.97 and with a 3.55 rear gear that's about 10.4 x torque multiplication in 1st gear. With the 434 I think you will have enough torque to blow the tires away on the street with either set of heads.

My TA has a 416 & the T56 Magnum 2.66 1st gear with 4.10's for about 10.9 x torque multiplication. It's way easy to spin the tires. I'm sure with 434 will have more torque.

​​​​​​I'd favor the TFS 260 LS7 type head between the two. With a ported MSD LS7 intake you'd have the potential option to spin a lot of rpm for more top end power later on if you decide to make changes. Being able to hang on longer before shifting can help when clowning on the street as well.

Either should be an excellent choice.


Smokey, That's a nice article on the TFS 245 vs TFS 260 with interesting flow numbers and coefficient of discharge details. Thank you for sharing.

​​​​For ~$2,700 set of TFS 245's or TFS 260's my choice would be another set of Reher-Morrison ported LS3's. (Used LS3's for $500 with a good CNC and quality hp valve job ~$1000 for total cost of ~$1500 to $1600) The RM's like most quality ported LS3's can make ~ 750 crank hp with the right intake and cam.

FWIW - On flow numbers,I my understanding is that high flow at .100 lift isn't necessarily so good of a thing. Air doesn't have much momentum and high .100 numbers can mean the it's easy for reversion to occur. Often when there a lot of Flow at .100 the valve job isn't ideal and will peak too soon.

My understanding is that way the stock type of LS 1.7 rocker works is the lower lifts only get about a 1.5 multiplication, this then ramps to 1.6 multiplication and hits 1.7 multiplication with mid and upper lifts.

To my way of thinking on a LS with stock ratio 1.7 rockers for a street car. Otherwise may have different views and better data but this is my rough understanding for 20+ years in the LS car hobby:

.100 high flow isn't good, equals reversion
​​​​​​.200 about 1.5 rocker multiplication, staring to establish momentum - fairly important flow numbers
​​​​​​.300 about 1.6 rocker multiplication - more important ramping up flow and momentum
.400 seeing full 1.7 multiplication, flow established, critically important airflow
.500 seeing full 1.7 multiplication, flow established, critically important airflow
.550 seeing full 1.7 multiplication, flow established, critically important airflow. About the max lift to avoid any side loading of the valve with stock rockers, intake ports that back up at this lift or right after are a sub-optimal design.or need a better valve job
.600 seeing full 1.7 multiplication, flow established but not much cam lobe duration is left so less important airflow, stock rocker is side loading the valve. Intake ports that back up at this lift or right after are a sub-optimal design or need a better valve job
.​​​​​650 seeing full 1.7 multiplication, flow established but not much cam lobe duration, at max limit of stock rocker, flow is less important, valve guide wear likely very accelerated with stock type rockers

Random comments

• ​​​​​​The best intake ports will flow to 1 inch lift and not back up.
• Intake ports that back up at .550 to .650 have an issue in the port or valve job or blow area
• Intake ports that sound dirty and turbulent on the flow bench are usually suboptimal designs.
• That "wing" under the intake valve that's temping to grid out on your new CNC'd heads maybe there to help keep the port stable at higher lifts. Wings are sort of 20 years ago.
• Looking at the head with valves out did the porter leave enough material around the valve guides or does it look paper thin? If it's paper thin don't be surprised if he valves fall out at 5,000 miles
• How high the Porter get into the port roof? There's good airflow gains to be found but if it's too thin it's going to crack.

 

 

Another Papa John's fan I take it? lol

 

The craziest thing is spending on aftermarket heads then factor the extra work needed to have a great head ( buy a high dollar tfs, mast,etc...then custom port work added? Think about it? ). I'd buy a brodix LS7 head as cast cheap and send them off. They sell 2 different versions normal and HD, $100 difference as cast bare each,which start at around $675.oo so the HD version as cast runs around $775