GN1 R or TA aluminum ported head flow numbers

ronviper

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I was told you have to work harder on the TA heads to get the numbers compared to the Champion. I am not a head porter therefore i personally cannot verify that. Ii would be interesting to hear from someone who worked on both heads.
 

Nigel

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Looking to add to a discussion on airflow. I think some well-established information on head design, valve angle, and flow characteristics should be considered and researched. The evolution of the Chevy small block to today’s LS based motors is a good example.

A flow velocity applied to a race engine head, especially a NASCAR head with an optimal valve angle and intake port shape, is not necessarily compatible with a Buick V6 production head or likely an aftermarket Buick head(I don’t own an aftermarket head, so I am guessing). I would think this is even more of a consideration when comparing an NA race motor architecture to a production based Buick turbo motor architecture. Parameters for a well designed race engine head, developed on a test stand with analytic tools that the rocket scientist of the 60s could only dream of, is not necessarily going to work on a production Buick motor. The millisecond you end up with flow separation in the intake port, you will lose your ram effect benefit and will not be able to recover the port velocity as cylinder pressure/mass flow(i.e. Improved volumetric efficiency). Some experimental data would be required for Buick head to determine optimal port velocity. The short side radius is usually the limiting feature, but I am guessing the valve seats are also important when the valve is full open(the seats are definitely important when the valve is just opening or closing). As long as the boundary layer stays attached(it is likely a turbulent boundary layer, do not confuse laminar flow with a laminar or turbulent boundary layer), and the surface is reasonably smooth so that you don’t lose too much energy due to friction, you can recover the velocity as pressure in the cylinder. Runner length/velocity tuning will determine the RPM at which the ram effect will be maximum. If you cannot recover the velocity(flow velocity exceeds the port capability to maintain an attached boundary layer), you have also just increased your pumping loses. So optimal velocity on a well designed racing head is not going to be the same for a production head unless the production head is the same as the race head. If you get anywhere near critical velocity, which I would not expect, that is a different discussion.

A note on pumping loses. If you could keep your crank case at absolute vacuum on your intake stroke the pumping loses would be zero. Since this is not the case, increasing pressure drop to the cylinder on the intake stroke means the piston has to work harder to displace the air in the crank case, thereby increasing pumping loses. If you cannot recover the port/runner velocity horsepower will be lost. Vacuum pumps or dry sump oiling can reduce crank case pressure and improve horsepower. On a boosted engine, intake pressure above crankcase pressure will drive the piston down, giving a pumping benefit. The intake stroke does note suck air in, there is no such thing as suction. The high pressure side is always the driver not the low pressure side.

On an NA motor, a tuned header can transiently drop the exhaust exit pressure below atmospheric(intake) pressure to scavenge the cylinder, for a certain RPM range. Not sure if this helps pumping loses that much, but it improves cylinder filling so it improves volumetric efficiency.
On a turbo motor with high back pressure in the exhaust, the pumping loses are high on the exhaust stroke, and obviously increase with increased in back pressure. Cylinder fill will also suffer from back pressure. A different turbine design can lower back pressure at the sacrifice of spool time. If you can lower back pressure to below intake pressure, cylinder fill improves, and you are now using exhaust energy to apply power to the crankshaft on the intake stroke while minimizing exhaust stoke pumping loss. You are now really making good use of wasted exhaust energy by not only compressing air(increasing mass flow), but also getting a net pumping gain through using the exhaust energy and by getting a completely clean intake charge(improved use of the heating value of the fuel).

I think you have two main things to look at for making power, the overall mass flow through the engine and the heating value of the fuel vs the energy value of the exhaust exiting the engine after the turbo/waste gate combined. If you increase mass flow, you can increase power. If for a given heating value of the fuel consumed, you can reduce the energy in the exhaust flow with the turbine you can make more power. The challenge is the power quality and the response time to make that power.

I would bet a paycheck that on a turbo motor, minimizing pressure drop on the heads is more important than intake port velocity. Maximizing the compressor/turbine combination for a given engine will outweigh other considerations so long as the head/cam design is correct for the turbo mass flow capability. With a NA motor the desire is to maximize volumetric efficiency at atmospheric conditions, a turbo motor does not have the same constraints, the turbo motor can alter compressor and turbine to match a particular engine and get the most out of it.
 
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Mike T

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Nigel based on your latest response and past conversations with you I have no doubt that you have extraordinary knowledge of flow.

You would be a great person to have on a development team. While porting my own heads some of your ideas regarding "entrainment" were considered.
 

Mr.Spool

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I would bet a paycheck that on a turbo motor, minimizing pressure drop on the heads is more important than intake port velocity.
the turbo makes the power. specifically the compressor ,shaft speed and size of the wheels being used,the engine has to be able to swallow it/in and out.the motor does not know if its an na or forced induction motor.the better the motor/air pump/VE/, the better the system can work.
 
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gunzandgearz

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the turbo makes the power. specifically the compressor ,shaft speed and size of the wheels being used,the engine has to be able to swallow it/in and out.the motor does not know if its an na or forced induction motor.the better the motor/air pump/VE/, the better the system can work.
That is correct when cylinder heads are ported for Max effort engines they are ported the same exact way you would a naturally-aspirated engine makes no difference ,in other words you don't Port them differently for a blown or turbo charged application valve size is determined by bore size, and port volume and velocity will be determined by engine rpm, it has to be a match system cam heads turbo cubic inches everything has to be taken into consideration but mainly bore size stroke and RPM plus turbo size has a lot to do with how it's all set up
 

grass doctor

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That is correct when cylinder heads are ported for Max effort engines they are ported the same exact way you would a naturally-aspirated engine makes no difference ,in other words you don't Port them differently for a blown or turbo charged application valve size is determined by bore size, and port volume and velocity will be determined by engine rpm, it has to be a match system cam heads turbo cubic inches everything has to be taken into consideration but mainly bore size stroke and RPM plus turbo size has a lot to do with how it's all set up
I got a question , isn't more important to port the exhaust vs intake side on heads unless you have a ported intake manifold
 

grass doctor

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I Was always under the impression that when you port and polish heads the exhaust side was the most important , I guess I was wondering if you don't have a ported /polished intake manifold why would you need the intake side on the heads to be ported or will you benefit from just porting/polishing exhaust side on heads
 

gunzandgearz

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I Was always under the impression that when you port and polish heads the exhaust side was the most important , I guess I was wondering if you don't have a ported /polished intake manifold why would you need the intake side on the heads to be ported or will you benefit from just porting/polishing exhaust side on heads
Well you can forget the polishing part cuz that's worthless as tits on a boar hog you can do it on ex. Side but never on intake sideand me personally I would never Port exhaust side without doing the complete heads
 
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grass doctor

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Well you can forget the polishing part cuz that's worthless as tits on a boar hog you can do it on ex. Side but never on intake sideand me personally I would never Port exhaust side without doing the complete heads
ok that's what I meant polishing intake side my bad, thanks for confirming, tits on a boar lol
 

grass doctor

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yes indeed I have some irons that have been ported but not polished just curious about that I also have been told that some prefer some turbulence on intake pending application
 

gunzandgearz

gearzandgunz
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;);)
yes indeed I have some irons that have been ported but not polished just curious about that I also have been told that some prefer some turbulence on intake pending application
Yeah whats funny is if you can hang with guys that build the baddest engines out there ie NHRA pro stock nascar,pro mod you can pick up alot of good info,again not that I know everything out there, but I have hung with and still do hang with a couple of the best induction system experts in the country and they have schooled me on alot
 

Nigel

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Nigel based on your latest response and past conversations with you I have no doubt that you have extraordinary knowledge of flow.

You would be a great person to have on a development team. While porting my own heads some of your ideas regarding "entrainment" were considered.
Thanks for the kind words, I wish I could do more building like you and less talking. I am slowly getting my car back together.
 
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Nigel

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the turbo makes the power. specifically the compressor ,shaft speed and size of the wheels being used,the engine has to be able to swallow it/in and out.the motor does not know if its an na or forced induction motor.the better the motor/air pump/VE/, the better the system can work.
The thing I would consider is that the turbine, compressor, and reciprocating engine all are a single system, so you have to consider it as whole.

As far as an NA engine is concerned, the atmosphere is a limitless supply of air at a constant throttle pressure, the same is not true for the turbo motor.
For a turbo motor, any change in intake conditions, impacts the compressor, which impacts the turbine, which impacts the engine. Some amount of crankshaft power is required to drive the turbine, the higher the back pressure, the more power required by the crankshaft to drive the turbine/compressor. If optimized(or semi-optimized) the trade is worth it, because the turbine is able to extract much more energy from the exhaust then you are using to pump it(possible to do much better, but you would lose too much turbine response). Also, any increase in mass flow by the compressor will increase compressor power required, but the offset in power produced is usually worth the pumping losses. The NA engine output is not limited by air supply, a turbo motor is limited by the air supply of the compressor if it does not reach some other limit first. As far as optimizing an NA engine vs optimizing a turbo, of course you have things that are the same, but also significant differences. The main difference pointed out is that the throttle pressure does not change, so using the pumping action of the engine to create an optimum intake velocity to give maximum ram effect is a way to trade pumping action/losses for VE. The way in my mind to do it on a turbo motor is to build a combo that matches max compressor mass flow at a CFM that matches the engine CFM capability while minimizing the pumping losses by also optimizing the turbine.
You cannot increase velocity without increasing pressure drop. The velocity increase would have to be worth the pumping losses across the better part of the operating range of the motor. When you run out on the compressor map, you cannot make it up with port velocity. Maybe I am wrong, but the optimum state would not require a trade in pressure drop for port velocity.

It is an opinion on my part, because I certainly do not have the coin to test it all out. I like talking about this stuff, so it is meant for discussion. I also understand it takes a lot more to build a fast car. So consider it in that context.
 

Mr.Spool

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When you run out on the compressor map, you cannot make it up with port velocity. Maybe I am wrong,
when you run out of compressor the power is done,all the things you are discussing are overlapping,its not a tradeoff.maxing out a turbo would require the engine to be optimized for that power range or the turbo will never see its limit.
 
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RUQWKNF

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Maximizing the compressor/turbine combination for a given engine will outweigh other considerations, so long as the head/cam design is correct for the turbo mass flow capability. ---

The thing I would consider is that the turbine, compressor, and reciprocating engine all are a single system, so you have to consider it as whole.
This ^^^^ is priceless JEDI wisdom folks.

The only thing I will add is this.
Combo is key, not simply throwing parts on the wall and seeing what sticks. Followed extremely close by the tune/tuner.
Listen closely to what the OG's have to say and or have done. This knowledge base, unfortunately for our platform, is slowly starting to fade away. That is why this board is so critical to the future survival of the Buick turbo v6. If you're smart, you'd be spending some time printing off some of this priceless material and preserving it on paper, vs taking the internet for granted thinking it will exist forever and just book marking the page to your favorites. It's also why I hung onto all of those news letters from eons ago. Facebook caters to the gotta have it yesterday, new owner crowd with numerous repetitive Q&A posts that used to be the norm here. Nothing against new owners, just saying, the traffic flow will go down because of other platforms of communication. Especially instant comms. I'm very thankful that we still have this site and members who still readily share their experiences and knowledge freely. Heck, I know I'm not a know it all and am constantly learning stuff on here all the time. Even though I guess I'm considered an OG. Lord how time flies...

These types of posts are priceless as for years, this info was very, VERY costly to us Buick guys. Think pay to play for these types of trade secrets / proprietary secrets and first hand knowledge.

Carry on guys, this thread has immense potential for all to learn. Especially if it branches out to more secrets with combos.
JEDI hand wave...
:cool:

-Patrick-
 
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