Don't want to get to far into the details, but I've been in and out of the hospital for the last month
Worse part is I can't drive ... for now anyway.
So my MAF testing is on hold.
Was pretty much done tuning anyway and looking forward to long term testing this summer.
Hopes are I'll be able to get back to it soon.

Everything you say above I agree with.
I think most people normally cruise around or run through the gears at part throttle.
Even with a "pegged" maf and a messed up LV8 (calculated) the ECM can handle most of that ok.
Then if they have tuned "full throttle", on a chassis dyno or street, with a wideband oxygen senor, in a sense they are "scaling" at full load (255 LV8) using the wideband feedback.
Having a properly sized MAF that covers the full range and proper LV8 (calculated) would mostly effect the middle range, between normal driving and W.O.T.
I don't think most people spend a lot of time there?
Maybe road racer?
With a coherent LV8 through the full range a lot more can be done with the timing tables also.
Anyway remember, to scale you need an MAF that has more range than 254 grams/sec at 5 volts output.



Continuing with the war on the working class, they have eliminated the "de minimis tariff exemption", which allowed goods under $800 to be imported tariff free.
A lot of small home business (house wife's) lost their ability to sell handbags, shoes, cloths, makeup, etc. to try a help pay the mortgage.
50 to 150 percent tariff, depending on someone's "mood"?
People like me lost the ability to order parts made from new technology's (not available in the USA).
And it won't ever be turned back (either party) because no politician has ever removed a tax once it's in effect.
One's on the working class anyway

 

hang in there and get better.
I've been sick for 2 week. just the flu. no big deal. still not fun.
taxes never go down for us.

 

https://www.facebook.com/share/r/19BKQsaWQT/
Hope you can pull the link. Interesting video showing flow with and without a velocity stack. I posted here so we could see such an obvious improvement. Also, I found the spiral grooves interesting!


EDIT: Based on the what's superimposed over my link, I'm guessing this site doesn't like Facebook posts. (You know....even when they are interesting or helpful). Here's an image showing the demonstration...


At least you can see the grooves. FWIW, the flow increased over 100cfm by adding the velocity stack!

 

one of my favorite velocity stack videos

 

Because of present health and physical limitations I haven't been able to drive my car as much as I had hoped.
Not an easy car to get in and out of and being standard shift doesn't help
The good news is no complaints with this new MAF.
Parts are holding up and still happy with the throttle response.

So ... can't drive, but what I can do is get the next phase ready for when I can drive more.

This MAF was always designed to be a 3.5 inch size.
I necked it down to the Bosch 3.0 inch size to fit my existing super charger pipes.
Quicker way to get to test these ideas out.
Went back and took out the size reduction and removed the air filter clamps mounts.
The calibration section remains the same.





We can see how much bigger and open the 3.5 inch version is.



The front u bend just needed to be enlarged to match the 3.5 inch inlet.
The rear u bend was enlarged to 3.5 inches on the MAF end, but I also widened it to provide more area around the bend.
Slow the air down to help it turn easier.








How much has any of these changes increased flow potential, decreased flow loss?

I set up (on my flow bench) my ported single plane, prototype "elbow" that's on my engine now in aluminum, and the 58 mm BBK throttle.
This is very close to what's on my engine now.
Going to test the various MAF and pipe combinations I've run over the years.
The bench is pulling through TWO runners (6 & 8) in all these tests.






The first test is the way I first installed this PAXTON kit back in the early 90's.
Stock PAXTON ducts and a BOSCH MAF with both screens in place.
Side note ... I had done a little cleanup and porting on these PAXTON pipes over the years.
I would consider this the BASE configuration.




The second test is my 3D printed supercharger pipes (version 1) and the Bosch MAF with screens.
These are the u bends I am running right now, but these parts I had wrapped with fiberglass just in case I needed added strength.
Turns out I didn't need them ... their ugly, but identical inside to the ones in the car now.






Test three is the 3D printed pipes and the SPECTRA MAF with just the front screen in place.
Didn't test with no screens, because I can't run it that way.



The fourth test is the 3D printed pipes with the 3 inch version of my Prototype MAF.
This is what's on the engine now.




The last (fifth) test is the full 3.5 inch design.
Version 2 front u bend, 3.5 inch Prototype MAF and the "fat" rear u bend.



The flow bench test results.




So ... is it worth moving up to the full 3.5 inch design?

I would say yes

With the PAXTON's limited cfm output, any reduction in loss through these pipes-MAF's means more boost in the intake manifold.

I need to setup the 3.5 inch MAF design on the bench and work out the new transfer function for it.

Shouldn't be to far from the present version with a little more range.

Test fit it under the hood and print out the final parts in the carbon fiber polypropylene material.

 

I'm amazed with the prototyping that you're doing

 

I’m kind of envious of young engineers today, with all these tools that we didn’t have.

CAD, 3D printing, 3D scanning, 3D printing aluminum & stainless … etc.

Makes you wonder what’s coming next?

 

I wish metal 3D printers were affordable. Also wish Inconel stainless was affordable. I built a heat shield for rocket diffuser out of Inconel. It has amazing properties. doesn't warp when welding and isn't hot to the touch after welding. I know Inconel can be 3D printed.
One thing I know is as technology advances the training changes and sometimes workers can miss very obvious solutions, because of heavy reliance on technology. people still need to think and problem solve. I have noticed how flawed A.I. is.

 

It's inspection sticker month, so I managed to drag my old behind around enough to wash and spray wax the old mule



Had to clean all the tools, tuning computers and spare parts out of the interior.

And put some motorcycle baffles in my tail pipes.




Even though I've never had any issues, I still hate hate hate getting my cars inspected

Must go back to my teenage years of old cars, open headers, and cars that wouldn't idle.

Letting someone else drive my Vette and jacking it up doesn't sit well either.

No emission testing anymore ... putting the car on rollers .. thank God.

The older guy I always went to retired, so I had to find a new shop.

Good guys ... and it went easy

The old C4 stopped the whole shop for half hour or so.

Talking to the old and younger guys about the engine, especially.

Was a time when no one looked twice at our old C4's.

Now even the younger guys where telling me I had a "cool" old car

 

nice, supercharged car. don't see that every day.
funny, I made inserts for my mufflers, because they were too loud for me.

 

Damn good increase in flow!

I guess it's OK that you can't drive it as much since it's not even in the car! Or, do you have a duplicate mule for fitting purposes? Otherwise, why pull it from the car for intake work? (I know, I know...It's probably mentioned way back on an earlier page?)

HOPE YOU CONTINUE TO FEE BETTER!!!!

 

Gave all my engine blocks away.

But I have shelf's and boxes full of parts.

Bought one of these “mock up” frames from SpeedWay to test fit my “things”.





Lot easier to move around

 

Set up to test the transfer function for the 3.5 inch MAF prototype.




Moved a little further to the left than I expected.
On the right of the graph is a rough calculation for the maximum horse power the MAF can meter.
850 hp is way more than I could ever need.




There is a ratio between the air flowing through the main body of the MAF and the sensor tube path.
The sensor path design is the same for both prototypes, just the area of the main body changes.
The nice thing about this design is that I have three different ways to increase the flow through the sensor path.

Make the slots larger so the vacuum, from the air passing over them, draws more flow.

Change the "Gurney Flap" design to help enhance the flow through the vents.

Or, increase the size of the sensor tube itself.



Increasing the senor tube is the easiest 3D model wise.
Increased from 0.5 to 0.7 inches, as a first try.



Moved to the right, very close to the 3.0 prototype curve.
I'm happy with that.




Test fit the parts and they clear the hood and throttle.

Starting to print out the pieces ... but I have another problem.



My favorite material choice is Braskem (Xtellar) fiber filled polypropylene.
The existing elbow's, printed in this material, have survived two years on my engine with no issues.
I'm running out of material, it's made in Brazil and the USA supplier won't order me anymore material because of the unstable tariff issues between the countries.
Changes weekly?
The only possible way is if they drop ship the material to me directly and I pay the shipper whatever the current tariff is.
And I need to buy a large enough quantity to make it worth their while.

So ... there's that

 

I haven't been reading much on the forum lately, but this morning I was catching up on your posts and realized how very close you have gotten this inlet to the shape that Garrett redesigned for GM to feed the turbo on the 2006 and up (not familiar with current parts though).

While there had to be some slight bends to allow for other parts, the shape is very very close. And it feeds the turbo on these diesels very very well.

The tube off the back goes to a resonator. Lots of discussions on the web as to what it does on that side of the turbo.

 

I have been fussing around with porting for years, but the “light bulb” didn’t really go off until I started playing with this flow bench.

We are all doing the same thing, moving air as efficiently as we can.

Reasonable that the end results end up looking similar.

My elbow has the same “short side” turn shape as most cylinder heads intake runners.

The intake runner (in the head) widens around the “short turn” slowing the air and helping it turn into the valve.

Makes sense the same widening works for turning air in a duct.

You start to see the common shapes.

In one of Darin Morgan’s “webinar’s” he talks about walking around a SEMA show and looking at the turbocharger kits of a very old and well known company.

He said “looking at their designs these people don’t understand airflow”.

So … you start to be able to see who does and who doesn’t get it

 

I thought you would like to know !

 

what I'm I missing

 

I finally found a supply of my favorite Carbon Fiber Polypropylene material (Braskem) in Spain, of all places.
And apparently there is no Tariff on shipments less than $800 from Europe until August 29th ... maybe
So I ordered a few shipments of material to last me into the future.
Still, with shipping and the strong Euro to dollar conversion, it cost me about $125 a roll instead of the $75 a roll it use to cost from Amazon.




Printed out my 3-1/2 inch MAF parts, sealed them with epoxy and a rough sanding.




I don't care that much about appearance.
Thin coat of paint and ready to install.





Just have to get up the will power to yank out the ECM, get a new BIN file ready and start tuning again.
The car is running so well right now, it's kind of hard to start all over again
Rather enjoy just driving it when I can.
But I know I have to complete this MAF adventure

A new future hurdle is that the large plastic company (Braskem) that makes my material is getting out of the 3D printing filament business.
Not enough profit for them?
So, I've been looking for alternatives.
You would think that would be easy, but it's not.
There is a dirty little secret about layer adhesion in large 3D printed parts using these temperature resistant carbon and glass filled plastic filaments.
Going to do a write up on this when I get a chance.

Till then I've been testing a lot (LOT) of materials and talking with vendors.




Some have been very helpful "I'll send you a partial used roll for free"
They didn't tell me it would be giant roles

Most of these materials need to be dried in a small reel oven to drive out the moisture.
These giant roles won't fit in the typical "home" reel drier.
I had to buy a double roll drier and section it, like a custom car, and add material (weld it all together) to make it large enough to accommodate these large rolls.






As I said earlier, I'll write something up on printing large heat resistant "usable" automotive parts on home 3D printers.

Just a lot of work to sit down and compose it.

Till then ...

 

What your missing is I have old eyes and old fingers … they don’t always work the way they use to

 

thanks for reply. I thought I knew what happen, didn't want to assume anything. Your information is valuable. making misstates seems to be part of my process.
been trying to compare runner entrance design effect on flow, with crossfire manifold.

 

I've been on the lookout for a nice clean CFI intake at a reasonable price to add to my collection.
PN #14031372 without the balance holes between runners.
Most on Ebay are filthy and overpriced.
('78CorvetteS.A.) here on the forum had a nice one for sale and now it's mine



First up is to flow bench test it completely STOCK.
I 3D printed out some velocity stacks with two inch diameter bores, to direct the air in the way the throttle bodies would with minimal restriction.



The results are around what I suspected from others.
About 158 average cfm and fairly well balanced.
Runner #1 is the worst, runner #7 the best.



What would be the best these STOCK runners could flow if everything was right?
Recalling my old test of a round straight runner with a cross section equal to the FelPro 1205 at different lengths.

Around 134 cfm/in-squared for a 6-1/2 inch long runner.

Measured the average runner at 1.375 H x 1.098 W = 1.509 in-squared.

1.509 x 134 = 202 cfm.

So ... that's what a pretty near perfect runners with a STOCK CFI cross section "could" flow ... our target

 

Decided to go down the path that most people that modify their CFI intakes travel, one step at a time.

The first thing seams to be "out with the diffusers".

So ... out they came



And the results.

Up from 158 cfm STOCK to 163 cfm average.

Reasonable increase, maybe not as much as some might have hoped.

 

The next step is to clean up the runner inlets.

Milled the faces straight without shortening the runner lengths.



Hand blended the inlets and rounded all the edges.



And the results.

Again a modest increase across the runners.

Up from 163 cfm to 167 cfm average.

Not helping as much as I hoped at these low flow rates

 

The third step was to port the bottom of the runner outlets out to the gasket size.

Used the FelPro 93317 as a template and stayed just a little inside it.



Milled straight in perpendicular to the face, and hand blended them.

Ported just the bottom of the runner and only blended up the side where needed.



The results.

The biggest increase so far, up from 167 cfm to 181 cfm average.

It's possible the two previous tests help this one along, relieving some of the inlet restrictions.

In hindsight, maybe should have done this modification first?

 

Quick question... I assumed all of these intakes were exactly the same, whether it came from an 82 TransAm, or an 84 Corvette. Are the balance holes in between the runners a bad thing? What effect does this cause that makes them undesireable?

This is probably one of the most interesting results... which I hadn't seen before... it literally emphasizes how some of the runners would be deficient compared to the others (like #7), so it helps you focus on which runners need more work.


Quick question about this. I've never removed these from either cross-fire injected car I've owned, but I've seen people remove them from Iron Duke motors with the 300 TBI (also has a "fuel diffuser"). In either case, they tend to increase horsepower, but the underlying concern was that they might actually result in improper fuel distribution. I know you're not measuring fuel delivery... and I don't know if this is even possible to do at home, but it would be interesting to see if you had all the ports hooked up, and measured the fuel (or whatever substitute fluid you sprayed into the ports) that actually reached each port.

You know how there's always that guy that says the GM engineers know best, and everything is perfect, and unless you do it that way, it's crap? That's definitely not me... I'm usually the person arguing with them. But I do question what the effect would be in eliminating these diffusers. I wonder if there is a way to improve them slightly? I opened them up a bit more, but I wonder if there's a benefit to keeping the foils, but grinding down the sides so you still get more air distribution? Seems like it's being affected by about 5 cfm... so you could probably improve that somewhat... like griding away in the red area here:

 

The "diffusers and balance holes" are long debated features of the CFI intake ... as you know

If you go way back to earlier tests I did in this long - long flow bench thread, the balance holes hurt the ultimate flow numbers.

I am an engineer, so I've been known to side with them "just doing their jobs".
That being said, these "diffusers and balance holes" scream of someone trying to fix something after the design was done.
The earlier intakes don't have the balance holes.
Could be cold start and running, emission problems, EGR mixing.
Maybe things that OEM's care about but we typically don't?

Just finished some smoke tests of just this issue, but haven't had much time to mull over them.

I'll post them now anyway.

I don't think I see any swirl from the diffusers.

They just look like "shear plates" to me to possibly help atomize the fuel spray.



This is the four end runners ... video at half speed.


With the diffusers on just two end runners ... video at half speed.


The diffuser in a clear tube ... looking for swirl.

 

this is awesome.
My cfm was a little lower with stock TB's.

 

went through my notes. I got very similar numbers. only tested runner # 1. also got similar gains from gasket matching.

 

old article. vanes intended to swirl the mixture and improve distribution. tempted to put a bore scope down tb while its running
Improvement or Impairment? To Modify G.M.’s New Fuel Injection You Have To Get With The Program

 

old article. vanes intended to swirl the mixture and improve distribution. tempted to put a bore scope down tb while its running
Improvement or Impairment? To Modify G.M.’s New Fuel Injection You Have To Get With The Program

 

Porting out the long six inch sections of the STOCK runners is a lot of somewhat difficult and scary work for anyone, especially a beginner

I what to see how close I can get to that 205 cfm number just working the inlets and outlets of the runners and the plenum area.

Everything I've done so far could be handled with a die grinder and a little skill.

 

Next step, flatten out (port) the inside turn on the runner outlets.



Removed about 0.10 inches just from the inside of the runner turns.



The results, another small gain from 181 cfm to 185 cfm average.

Lot's of small gains, but they do add up.

 

I have been avoiding touching the EGR duct.
Figured anyone interested in just these "easier" modifications might want to keep their EGR functioning as designed.
And runners #5 and #7 don't appear to be hurting because of the EGR duct right on their heads.
Decided to take one step towards removal and just clear the end from the crossover area.
The EGR gas would still dump into that center channel.



I didn't expect much of a flow increase, but did figure the balance between the runners would change.

Neither changed very much?

Very small losses and gains ... in the noise at this flow level.

That's a bit off a surprise

 

porting the full length of runner is more difficult. I bolted an intake manifold gasket on the intake to protect gasket surface. also bolted aluminum striped to protect top plate gasket surface.

 

Yeah, my assumption is that it was for better fuel atomization. I guess I should ask, has anyone seen any issues (fouled plugs, etc.) as a result of removing these things? All I've ever seen (Iron Duke included) is people warn about removing them... but then I also see people showing an increase in horsepower by removing them.

I definitely think they were an afterthought to solve a problem... I just wonder what that problem was.


That's an excellent article... thank you! It even mentions the fabled 2.5 Iron Duke, haha...



What are you using to get in there? I've ported one side of the intake using a hand-held dremmel, but can't really reach in there. I had a flexible attachment, but it didn't seem to do what I'd hoped. My goal was only to use a sand barrel and smooth out the inside, not really attempt to port it. Though... I did port the cyl head side and the curve like you did... just with less intention and forethought... haha...



Ugh... I really wish I had done what you did... I knew I didn't want that arm reaching all the way out into the center, but I cut it off right at the EGR opening. In hindsight... I just assumed the EGR gasses would be disbursed anywhere... but in reality, having it dump in the center would have been more ideal for better / equal distribution. The ECM uses this to cool the pistons, in addition to improving fuel economy... and I kind of ruined that. I do plan to keep my EGR... but I assume if people are running without an EGR and aren't burning their pistons... and since I don't plan to take a drive from Fort Lauderdale to Juno Alaska, then I'll probably be OK.

I definitely think the readings are "in the noise" as you say... within the margin of error. Doesn't seem to necessarily make a difference. I didn't see above, but for your readings, are you taking multiple readings and then just averaging the three... or are they dead-on every time?

 

Porting the long CFI runners is a nasty job

You need an arsenal.

Mike here on the forum has done it a few times.

Haven't decided if I want to go that far yet.

I'm getting old and I can't see anymore, so I have to sit down when I work.

I have a heavy apron and port in my lap now.

Lot's of light.

 

Here is an interesting side journey.

I have a some Bosch MAF's kicking around and putting one on each throttle body is an effective way to measure and compare their flow.

So I did

I have one MAF on each throttle body to balance the flow out, but I swapped the same one (side to side) to take the actual measurements.



I just measured the odd runner side (#1 #3 #5 #7) and remember their inlets are closer to the even side throttle body.
Tested the balance for a low and high flow rate.





In the low flow test the odd side TB averaged 25% lower than the even side TB (range 38% to 16%).

In the high flow test the odd side TB averaged 14% lower than the even side TB(range 17% to 10% ).

So it moves toward better balanced as the flow increases.

Why would this matter?

For dual carburetors it wouldn't, because they meter the fuel to the air passing through them.
So the air fuel ratio coming out of each one would be correct.

I'm not an expert on how the CFI ECM drives the injectors, but figuring 1982 electronics, guessing they must be batch fired together.
If so, the two throttle bodies are dumping the same amount of fuel out, but we know they aren't flowing the same amount of air.
For the short cycle of time one odd side runner pulls air, the even TB would run lean and the Odd TB rich.
With the better balance at higher flow and the increased turbulence in the plenum helping mixing, maybe this doesn't matter.
But at low air flow rates, I bet it does.

Now what if a desperate engineer put large "balance" holes between the odd and even runners?
At low flow, when an odd runner pulls air in, some would follow the normal path, but some would travel through the hole from the even runner and the opposite TB.
Might be enough cross feeding to even out the flow between the TB's at low flow rates.
The magic here is that at higher air flow, the air would have a harder time traveling through the balance holes and act more like a normal runner.
But we know from testing (way back when) that the holes never become completely invisible and they do hurt the ultimate flow numbers.

A theory anyway......
A bad picture of these balance holes.

 

Ok, that makes sense... I think all I want to do is just smooth out the runners on the inside, so I just need to buy another flexible attachment.

I totally get it being old. I'm not really old / old yet... I'm 47, but when I was lesser ahead in my career, I would restore 1960s / 1970s Swiss and German mechanical watches for a quick buck. Shameless plug for my abandoned YouTube channel that pays me $150 bucks a month with only 3 videos posted in the past 2 years.


I could disassemble them without needing magnifiers. Now... I can barely do it WITH the magnifiers. I also have to use different glasses for different things. I'm near sighted, so I need glasses to see when I drive, but I need glasses to see up close and nearby (even though I'm near-sighted), otherwise I have to take my glasses off and hold it back some distance.

Just quick question... do you see any benefit to polishing the inside of the port? Or does that hurt when I'm trying to improve fuel atomization?


I just went into the garage and stuck my fingers into the runners to see if I had the holes. Mine are solid... so it doesn't look like I have the balance holes. This is a spare lower intake manifold that I bought off eBay. No idea where it came from... but I figured I'd port one while the original one stayed on the car... so that's good to know that I lucked out. Mine doesn't look anywhere near as nice as yours... haha... but nothing some clean-up can't do. I'm going to finish porting it before I clean it. I'm going to take it to the machine shop to have the EGR bolt holes helicoiled though... they were stripped.

As for the injectors though... the injectors are different on CFI. The front and rear injectors have a different part number. I always forget, but one does in fact flow about 2lbs more per hour than the other one... I just can't remember which one does which...

 

Very cool on the watches

Here is my opinion, and as they say “everyone has one”

There are still people that expect porting to be polished and fancy.
Usually they are people that pay others to do their porting and expect it.
And …. there are plenty of porters more than happy to charge big $$$ to do it.

From what I have seen, most top level porters have moved to a “burr finish”.
Especially for a “wet flow” application.
Smaller boundary layer and better fuel atomization among other things.

Some of Brad Speier’s work, from his web site.

 

OK, awesome... I get this... so wet flow application being TBI and carburetor, as opposed to say, TPI / MPFI where it's being injected directly above the valve... so in THAT case, you'd want no turbulence at all in the air flow... but in this case, because we're TBI... there is definitely a benefit.

Thank you for doing all of this. It looks like, with only minor screw-ups (cutting off the entire EGR neck from inside), I've mostly done what you've done. Not out of any science, just casual luck. It's really nice to see numbers attached to this stuff, so I do appreciate it! Thank you!

 

I agree with your opinion. I've read that roughness helps with atomization. tested burr finish, 40 grit, 60 grit. no real cfm difference. only things I've seen being polished is combustion chambers too eliminate hot spots and exhaust ports.

 

Dumb question... any way to clean up the exhaust ports while the heads are still on the car? I realize all the risks, just curious if anyone has tried it with some success (like sticking a rag deep in there or something. I have to keep stopping myself at a certain point, because with this car, if I allow myself, it'll become a $30k project. We spent $20k plus restoring a Fiero (my daughter and I) because we couldn't let anything not be perfectly restored. It was a great experience, but at the end of the day, we have a 4cyl 5-Speed Fiero that's probably worth $8k to the right buyer, haha. I paid $4k for this Corvette, and assumed probably $10k tops for renovation costs... and I know if I don't limit myself, I'll end up pulling the motor and then it'll get very real for my savings account.

Last question for you guys (until I think of something else to ask).

Do you have any suggested tools for polishing inside or just smoothing it out... like maybe a wire-brush attachment on a flexible shaft?

This is what I've done so far... it's not great, but I basically used the EGR staining as my guide...



I'll have a completely rebuilt top-end to go along with it...



And the freshly repainted 80s space ship looking air cleaner cover...

 

the way I got over 200 cfm was to increase the CSA of the entrance. only tested runner #1 though.

 

I wouldn't do anything to the exhaust port. the restriction is the exhaust manifold.
I think the intake manifold ports can be cleaned up with 1/2 tree or flame. can use a drill to clean up port. not very hard to do.
Buy Oval, Tree & Flame Shape Drag Cuts | Burrsforless these burrs are easy to control

 

I think you figured it out. the reason for the port hole. tested untouched #1 #3 #2 runners, with and without holes. The holes lowered the cfm for runners #2 #3 runners too runner #1 levels. must be equalizer holes. I would have never figured that out. I did equalize the runner flow on current manifold. manipulated entrance and bias center dividers. I guess that could be applied to unwelded runners. that would take testing.

 

Thanks for this!