TBI AirFlow

[airdeano]

close to one ive done was a wider radius but only to include
the injector pod arrangement. this was years before working
with the superflow. for a port fuel system itd be a killer idea.
the holley 4500 dominators has an tube similar for torque
tuning.
the lower left pic would show better air draw if the lower lid
entrance was .25-.50" higher than the bell opening of the stack.
entrance of the stack vs filter can be as critical as placement.
ill also try the salad bowl option if i can find one close...
airdeano

[oldred95]

Originally Posted by airdeano

close to one ive done was a wider radius but only to include
the injector pod arrangement. this was years before working
with the superflow. for a port fuel system itd be a killer idea.
the holley 4500 dominators has an tube similar for torque
tuning.
the lower left pic would show better air draw if the lower lid
entrance was .25-.50" higher than the bell opening of the stack.
entrance of the stack vs filter can be as critical as placement.
ill also try the salad bowl option if i can find one close...
airdeano

I feel like an idiot. As soon as I posted that I thought, that was a tune port injection wasn't it. That would be ideal for TPI. Yes you are correct the guy would really benifit be raising the air cleaner housing.

[va454ss]

Originally Posted by oldred95

Just curious as to whether anyone on the boards has ever made one of these . I wonder what kind of wet CFM's it would flow.

I have one of those without the velocity stacks and the injectors in the stock location. Plus, a bit of massaging.

Pics here: http://www.imagestation.com/album/?id=2134511718

[CKTA]

Good info, linked to this thread.....http://www.fullsizechevy.com/forums/...=1#post1478599

Does anyone want this made into a Stickie?

[oldred95]

Originally Posted by CKTA

Does anyone want this made into a Stickie?

I think we should.

[kdrolt]

Some related info here:

Flow measurements & discussion:
http://www.thirdgen.org/techbb2/show...+m easurement

http://www.thirdgen.org/techbb2/show...+m easurement

Flow stuff and wet/dry flow:
http://www.thirdgen.org/techbb2/show...+m easurement

[502HO]

What can us guys who have BBC already do for more airflow? My 502 needs alot more air and I have the stock 454 TBI mounted.

[kdrolt]

Originally Posted by 502HO

What can us guys who have BBC already do for more airflow? My 502 needs alot more air and I have the stock 454 TBI mounted.

Start here and then follow the thread(s).

http://www.thirdgen.org/techbb2/show...ight=%2Bmef i

You should be able to use the same set up, sans blower, but you will need to custom tune the fuel delivery at least somewhat, since the 502HO might be quite close to the GM marine set up that I cited in the above URL. HTH.

EDIT: GM is now up to MEFI-4 (or MEFI4). See:
http://www.gm.com/automotive/gmpower...rine/index.htm
http://www.gm.com/automotive/gmpower...marine_EFI.pdf

[TITANIUM]

I really wish someone would do some L05 head (Swirl Port) air flow tests to justfy that they are crap like everyone says. I want numbers.

[kdrolt]

Originally Posted by TITANIUM

I really wish someone would do some L05 head (Swirl Port) air flow tests to justfy that they are crap like everyone says. I want numbers.

Here's four threads that have swirl-port content. The first one lists the dyno number, flow numbers, and track numbers before/after the porting was performed.

http://www.thirdgen.org/techbb2/show...&highlight=LO5

http://www.thirdgen.org/techbb2/show...hreadid=177465

http://www.thirdgen.org/techbb2/show...ght=%2Bswi rl

http://www.thirdgen.org/techbb2/show...ght=%2Bswi rl

The viewpoints boil down to three basic groups:

1. People that say the swirl port heads s*ck; these people have no data to support their claim other than having read the posts of "experts", or based on looking at the ports and concluding that the port is obstructed so it can't be any good;

2. People that have data, either flow data, or dyno data, or track data on them, in either stock (unported form) or after porting, or both.

3. People that don't know and haven't formed an opinion.

I'll add that Vizard, among others, has said that swirl (rotating mixed air/fuel flow within the cylinder) is very important to assist combustion because the flame speed of air:fuel is fairly slow, so somne amount of swirl is helpful in making power, and the more swirl there is the better the forced convection of the flame. Higher swirl means less ignition advance is needed, and the less advance the more the cylinder pressure can be maximized after TDC.

That means there is a 3D plot tradeoff in swirl (x) vs airflow (y) and hp (z), and that subtle engineering point is completely overlooked during the discussions. I'd like to understand it further myself.

After seeing Dyno Don's results, I conclude that the unported stock swirl-port heads are much like other stock unported Gen I heads -- they aren't very good for performance, but they are good for emissions (fast burn head design) and don't need much ignition advance to make optimum power. I also conclude that when ported they seem to do MUCH better than almost everyone seems to believe. After mild porting, the absolute flow numbers are decent, but not great..... but they still managed to make excellent power. And that confirms the notion that, as Vizard says, there is more to making power than just by looking at cfm values alone.

Anyway, read the threads above and decide for yourself. HTH.

[TITANIUM]

Originally Posted by kdrolt

Here's four threads that have swirl-port content. The first one lists the dyno number, flow numbers, and track numbers before/after the porting was performed.

http://www.thirdgen.org/techbb2/show...&highlight=LO5

http://www.thirdgen.org/techbb2/show...hreadid=177465

http://www.thirdgen.org/techbb2/show...ght=%2Bswi rl

http://www.thirdgen.org/techbb2/show...ght=%2Bswi rl

The viewpoints boil down to three basic groups:

1. People that say the swirl port heads s*ck; these people have no data to support their claim other than having read the posts of "experts", or based on looking at the ports and concluding that the port is obstructed so it can't be any good;

2. People that have data, either flow data, or dyno data, or track data on them, in either stock (unported form) or after porting, or both.

3. People that don't know and haven't formed an opinion.

I'll add that Vizard, among others, has said that swirl (rotating mixed air/fuel flow within the cylinder) is very important to assist combustion because the flame speed of air:fuel is fairly slow, so somne amount of swirl is helpful in making power, and the more swirl there is the better the forced convection of the flame. Higher swirl means less ignition advance is needed, and the less advance the more the cylinder pressure can be maximized after TDC.

That means there is a 3D plot tradeoff in swirl (x) vs airflow (y) and hp (z), and that subtle engineering point is completely overlooked during the discussions. I'd like to understand it further myself.

After seeing Dyno Don's results, I conclude that the unported stock swirl-port heads are much like other stock unported Gen I heads -- they aren't very good for performance, but they are good for emissions (fast burn head design) and don't need much ignition advance to make optimum power. I also conclude that when ported they seem to do MUCH better than almost everyone seems to believe. After mild porting, the absolute flow numbers are decent, but not great..... but they still managed to make excellent power. And that confirms the notion that, as Vizard says, there is more to making power than just by looking at cfm values alone.

Anyway, read the threads above and decide for yourself. HTH.

Thank you for that post. I am glad that I am not the only one that wants to see data and not opinions.
Again, Thank you
TITANIUM

[DeanHensler]

I've got a 93 K1500. Rebuilt the motor about 8 months ago using a set of Vortec Heads and a mild crane cam (# 114122 if you want to see the specs). Got a Walbro 190 fuel pump, modified the TBI fuel regulator to allow 19 psi of fuel and had a custom chip burnt for the application. Well, as expected I'm used to having more power than stock and want more!

What did I read about a injector pod spacer? Whats that?

[kdrolt]

More swirl port head (193 casting) flow data. See the recent post here:

http://www.thirdgen.org/techbb2/show...wi rl+%2Bport

[airdeano]

got new TBI fixture built for BBC throttle body... flow-rates soon!
airdeano

[Sam K.]

I must be reading the graph wrong because it looks like the bone stock/green line flows better than the other two. Can someone explain this to a newbie? I have a TBI 350 that I intend to use for towing my drag car and would like to bolt on a few extra ponies. But, I'm unsure where to start and the spacer sounded good until I saw the chart.

[airdeano]

the green line is better, but there isnt any injectors, no
injector pod installed to impede air-flow.
the blue line represents the fully assembled TBI.
this was to show how much air-flow is influenced around the
injector pod. products that spacer that injector pod farther
away from the bores shows the gain in air-flow. the red-line
shows that with a pod spacer installed, air-flow is 20-40cfm
short of not having the injector pod installed. but because
these trucks need fuel.. they need injector pods.. and spacers ,too!
airdeano

[Sam K.]

OOOOOOOOOO Ok. Now it makes perfect sense. By "nothing installed" I thought you meant it was a stock assembly instead on no injectors. Thanks for clearing that up. So who has the best prices on spacers & what is it going to cost me?

[ImpalaGuy]

Originally Posted by airdeano

i just got done doing a flow rating on a GM TBI for:
4.3 - 5.0 - 5.7L TBI applications
the blue line represents a throttle body in full trim (injectors, injector
pod) no air cleaner.
the red line represents a throttle body in full trim with and injector pod
spacer installed (injectors, injector spacer and injector pod) no air cleaner.
the green line represents a throttle body with nothing installed.
the column on the left is air-flow in cubic feet per minute
the row underneath the graph is throttle position rated in volts from
a stock TPS.
the test was run with 1000cfm @ 28.00" temp 68.5°

making a big-block TBI fixture and will compare flow rates.
airdeano

airdeano --
In your flow tests, did the TBI have the collar installed? I'm talking about the ring that seats to the air cleaner and holds it off the TBI.

Also did you ever get a chance to flow the 454 or modified 350 TBIs? Having hard data like that is awesome.

[oldred95]

Another idea I got was what about modding the TBI spacer to look like this one? I'm not sure how the flow bench is set up or how it works but the theory is that each bore in the intake manifold can draw air and fuel in from both bores of the TBI at the same time. What do you think?

[airdeano]

impalaguy,
no the test was run barebones.
the BBC throttle body fixture is made, but getting the time to do the test is
tough.
old red,
if you send it to me ill flow it for you. but first you should do a test with and
without to verify if you have done any better. 1/4mi, 1/8mi or a measured
spot vs time
airdeano