Its all about flow!! whats holding you back....
 

Well for sometime now wanted to post about how crapy the tpi snorke is but ya.... heres some other intersting info

The following airflow tests were performed on the University of Northwestern Ohio's SuperFlow SF600 Flow Bench. All CFM values are corrected for airflow at 28 inches of water.
Air-Flow

Throttle Bodies

Stock TPI/LT1 48mm Throttle Body w/o airfoil -- 783.0 cfm

Stock TPI/LT1 48mm Throttle Body w/ airfoil -- 821.9 cfm

TPI/LT1 52mm Throttle Body w/o airfoil -- 848.9 cfm

TPI/LT1 52mm Throttle Body w/ airfoil -- 898.8 cfm


Mass Air Flow Sensors

Stock TPI Bosch MAF sensor w/ screens -- 517.8 cfm

Stock TPI Bosch MAF sensor w/o screens -- 658.4 cfm


and you can take it from here

;)

pretty interesting.. thanks for posting.. gives us some useful info on what we should be using for our application

indeed, no problem :)

the MAF isn't even the most restrictive part of the TPI system....

im just putting these up for now....

Re: Its all about flow!! whats holding you back....
 

Jesus, who would need more dry air then that! I never thought I would need an aftermarket TB, but this was the final nail.

Wow thats some good air flow. I went with the 58mm . :D

Most interesting to get independent test results from reputable sources such as a university. I have only two comments to make. First could some one provide a link to the source or obtain a copy of the university's data, scan it and post it for verification. I do not doubt your information but it would be nice to have the results posted. Second, someone may want to approach the university to do some flow tests on the TPI and TBI heads to complete the air pathway flow tests. I have seen some flow tests for some heads but it would be nice to have something from the university on this. Nevertheless, good work on finding this information.

Right now it looks like the MAF from the chart. Hehehehe. Next I will be going to the 3.50" Mufflex exhaust sytem. Then do I change to the Speed Density system??? If I do the engine should be able to breath in all the air it can and expell all the air it can with my current combination. Going for 400 TPI HP at the crank. :D

That is a substantial increase (27.1%) by removing the screens from the Bosch MAF sensor. My only question is why would you need a throttle body that flows more air than 658.4 cfm? I am not an airflow engineer; however, it seems to me than a system flowing air is only as good as it’s most restrictive component. I would be interested to hear others views on this subject.

I bit of research and here is the answer to my first question.

http://dtcc.cz28.com/flow/

Personally, I'm a MAF type guy. My understanding is that the MAF is not refered to during WOT FE mode, so the ECM limitation of 255 grams due to the 8 bit ecm shouldn't be a restriction. If that's the case, 658 CFM of DRY air is plenty of room for most applications.... and blowers basically remove that restriction. Remember,dry airflow is a LOT more air than the wet ratings for carbs, and I know of more than one carb'ed 350 making gobs of power with just 650 CFM carbs.

Bottom line is that I don't see the maf as a restriction in 99% of the cases... maybe in a race only NA big displacement applications.

Then again, SD can be more predictable, and requires less maintainence overall - but as far as airflow, I'd have to agree, the maf unit itself isn't the restriction everyone makes it out to be.

Very interesting. Airfoils actually do help performance. Buying an airfoil is a cheap alternative to buying a 52mm throttle body and comes close in terms of flow.

I'd like to know how much the individual runners of the TPI setup can flow, that'd be interesting.

Hmmm,

Actually there is a link here somewhere to all that info as posted by NorthWestern.


Its not new onformation by any means.

Why do u think myself and others have preached about not wasting $$$ on larger throttle bodies? Heck, GM uses a twin 48mm on the RamJet 502.

I wouldnt worry about a bigger TB until bottom 12 range, a large motor or something your spinning to the moon.

Sides that $300 u just wasted can buy you runners or a base, which is where u actually need help at anyhow.

later
Jeremy

Restrictions are ADDITIVE on top of eachother. If you put 2 things in a row that each flow 750 CFM you will get less than 750 CFM through them both. Don't ask me for the math.

Carbs are basically just a single point of restriction - the carb itslef. A big open element air cleaner above isn't much of an additive restriction.

FI you have to go through the air cleaner, buncha ducting, the MAF, some more ducting and finally the TB. Each piece may flow fairly well but the entire intake system as a whole becomes restrictive the more crap you put in the line.

so by this would you recommend a throttlebody thats larger than stock?

that would make sense cuz your taking out one restriction to make less restrictions overall, and that should increase airflow. now only the ducting, filters and airbox are the major flow restrictors, and the MAF plays alittle restriction role as well but not as much as the others

Thats also my theory. I went to a big K&N air filter on my TPI. 3 1/2 inch pipe from air filter to MAF. Then MAF to the 3 1/2 inch LT1 elbow. Then the 58MM throttle body. So the MAF with the screens removed and fins cut is the "weak" point in my intake system. Allen

This may sound stupid, but are you going to see how much the stock airbox and an open element/cone filter can flow? Maybe whole systems together as well?

Right. What would be interesting is to see the flow of all the components attached to one another.

I have seen this in part and the total is less than the flow of the weakest part. Mainly on intake manifolds, runners and heads. Allen

Well, yes and no. In theory, they are NOT additive. However real world takes into account turbulance. Kinda like driving through a toll booth at 100mph while drunk. It's big enough sure, but good luck not wrecking!!!

....which is why so many people swear by LEAVING THE SCREENS IN!!!! It smooths out the air making the NEXT restriction LESS off a restriction. (see toll booth analogy)

For the record I can't take credit for the toll booth analogy. I don't remember where I heard it, but it was in regards to the screens in the MAF.

I can buy the cumulative argument, to a certain degree, and I can certainly understand the difference between the theory and real world air flow. In relation to our cars we have a MAF sensor flowing 517.4 CFM or 658.4 CFM would a throttle body airflow increase from 783.0 CFM to 898.8 CFM about 1 foot from the MAF sensor pull any more air through through that sensor? This would have to consider all the real world bends and any rough surfaces in the ducting from the throttle body to the MAF sensor. I do not know.

Yes and no. It will pull more air, but it will require greater effort. Effort = energy = restriction. However, it's not a huge restriction when dealing the the amount of air we are dealing with.

Here is something else I have thought about on this subject. Read the following and give me your thoughts.

Take a 305 cubic inch engine for example. 1 cubic foot equals 1728 cubic inches. Therefore, a 305 cubic inch engine equates to a 0.18 cubic foot engine.

Suppose the engine is operating at 5000 RPM, which is close to the maximum for our TPI engines. An intake stroke only occurs one stroke in four. In the absence of a turbo or supercharger the induction system does not compress air on the intake stroke. Therefore, a 305 cubic inch engine is sucking in the following amount of air at 5000 RPM:

5000 RPM/4 x 0.18 cubic feet = 225 cubic feet per minute

or 225/8 = 28 cubic feet per minute for each cylinder

So if we know the engine is taking in 225 cubic feet per minute the above airflows should be more than sufficient to permit it to breath.

Now take this one step further I have seen flow test data that indicates 187 heads at .500 inches of gross valve lift will flow 165 CFM on the intake. If each cylinder can only suck in 28 CFM at 5000 RPM these heads should be more than sufficient. Is there a problem with my math or logical? I would be interested to get others comments.

It's nice to see some results posted like that. People are always on here saying how removing the screens of the MAF and adding a airfoil are a waste of time and money. Well they now stand corrected.

By "They" do you mean YOU stand corrected when you read Abubaca's post? Appologize later for your stupidity :D


BC GTA, that would make sense ON PAPER, but once again, that's when the old thing about "Because X Y and Z math says this" doesn't really mean it's true. The Exhaust guys who cry about single 3 - 4 inch pipes being enough fall into the same "Math rules" mindset and then get all upset when a true dual guy gains power numbers over a single 3-4 inch unit.

Basically, what I'm getting at, is while the math LOOKS good, it's hard to deny that swapping out a set of trickflow heads that flow A LOT more will gain gobs of power over swirl ports. Sure, by the numbers, swirlies flow enough, but it takes them energy to flow those numbers, where the trickflows do it rather effortlessly. Bigger rules, once again. (not biggest, just bigger)

I don't think your math is correct...well, yours is, but I don't think the formula is correct for CFM at RPM. I had a site saved once, and as I recall a 350 cu in engine would require about 600CFM of air at 5400-5800RPM (don't recall exactly). I don't see an engine with 45 less cubes requiring only 225CFM at 5K.

Could be you need to double it since there's an intake event happening twice? I dunno. I never got that deep into how things work...makes my brain hurt.

The screens may or may not smooth out the air...but they most certainly slow it down. And velocity is what makes a TPI work well..pulling the screens with other intake mods is a dyno proven mod. I've felt a gain on my set-up with a ported plenum/foil/CAI,after pulling the screens.So have plenty other people.
The numbers posted have been well know generally for quite some time.Removing the the heat sinks in the MAF bumps it up to around ~730 cfm...far more than most street motors will need...and of course supporting the argument that the MAF itself is not the restriction. Any good engine builder will tell you that you can't put an honest hp on CFM's alone...you can get a ballpark figure but its not exact.

Maybe a clarification of terms but the additive effect is correct in the sense of pressure drop. Each restriction in a system will cause a reduction in pressure downstream. The end result will be the additve resistive elements of the circuit. The density of the air entering and flowing through, and finally ending up in the cyclinder is the objective. Pressure is only equal when not moving, air moving through a restriction is less dense due to the pressure drop and therefore reduces the fuel requirement to obtain the proper ratio for building power.
If there were optimum filling, then power is maximized by utilizing the FULL air:fuel ratio.
The cylinder always holds the same amount of volume, weather it be in a vacuum or not. How dense that air (pressure) is at that point is the key.

I have never seen proof of the screens robbing power. At least not at the power levels we're discussing.

Obviously, and it doesn't take a test to prove, the screen is a restriction. It's in the path of the air so there's no point arguing it impedes airflow. That's a given. The little sensor inside the MAF tube is also a restriction. Why don't you take that out too? ...but then we all know what'll happen, but since the car will still run without screens, heck, rip 'em out.

What has been proven, and of course I don't have that proof in front of me, is that the 'puter get's a much more accurate reading with the screens in.

...and if the screens aren't needed, why are they there?


...in the end, your car is faster without screens. My car wasn't any faster when I tore mine out YEARS ago. I currently have a MAF with screens.

Here's why I don't like the screen mod, and why I don't buy into it:

Forget the tech for a minute. When I bought my Iroc, it had two of the three required mods. It had a Flowmaster, it had K&N's. I took it upon myself to use my master mechanic skills and tear out the screens with a pencil.

I'm not ripping on Flowmaster or K&N. I know plenty of sweet cars with massive power using both of those products, but those 3 mods are more common on our cars than regular oil changes. EVERYONE has done it!!!

There's a good thread on the exhaust board debating the Flowmaster issue, and it's fair to say that it's a toss up. Maybe the FM costs a pony here or there, maybe nothing you'll ever notice, and maybe you like the sound. It's cool, and plenty of people making big power run 'em. Same with K&N. Maybe they don't actual "filter" the air very much. Bah, who cares, they give ya cool sticker. Regardless, they're super common among fast cars. But then you come to the screens. Once you're into the motor enough to really know what's going on, most people chose to leave the screens or get rid of the MAF all together. I'm not saying that anyone here didn't see a gain. I can't prove they didn't. I'm just saying that when you actually do your research, when you actually talk to people who've come across this issue, most will tell you there's really no consensus, no facts, no tests, and in the end they're still making big power, might as well keep 'em. ....and that's not to say there's no TGOers here who completely disagree. I'm no expert. I'm just voicing my opinon.

If I recall the screen in the back of the MAF is to protect from backfires...the front is to stop any debris that got buy the filter/and perhaps help give the computer a better reading.
It boils down to the technology...if our meters were frequency based like the newer MAF's we wouldn't be having this discussion.
And till this day I just don't understand why some company won't spend the R&D on getting a frequency based MAF to work on our set-ups...or even something like the ford where it can be recalibrated...I guess if it could be done it would have been done by now..as a product like that,you couldn't make them fast enough.I know I'd buy one.
I know the WElls unit will not work with its screen out...it throws a code..it is calibrated for the screen in..so why can't they expand on it and have a set-up that can be reprogrammed/calibrated for removing screens/more mods ect.I guess it just comes back to the technology.The screens may help with the wire getting a good reading but that is what prom tuning is for too...with the screens out,and proper tuning in the prom I'm sure that it can be made to run optimal.

Good discussion.

I can understand how air density would affect airflow. I can also accept that it takes work and the expenditure of energy to suck the air through the air filter, through the ducting, through the MAF sensor, through more ducting, throttle body, plenum, runners, manifold and into the cylinders. The further air has to travel the more work and energy the intake stroke has to do and expend to suck the air into the cylinders. Bigger air passages will generally permit more volume of air to be pulled through them than smaller air passages.

It is just hard to understand the numbers, which are so profoundly different. Air density must be one of the major factors here. Distance from the valves to the air cleaner is another factor in air flow. Real world inefficiencies and the cumulative effect is another factor. I suppose as the air tumbles around in all that ducting and other parts, from the cumulative effects of air friction, it takes a much bigger air passages to suck the air into the cylinders.

well, before i took my screens out, the car occassionally threw a code and it was becuz the sensor plug that sometimes got loose.

i took my screens out and have had no problems what so ever. seems to run as strong as ever. no real difference i could notice

the only reason i did so was because the airbox looks and is so restrictive. the part over the radiator is so small and the filter boxes have alot of shields to prevent water from entering, and thus prevents air. i cut those boxes out, and took out the screens to try to squeeze as much airflow as i could out of it. it was a free easy to do mod and no doubt in my mind, the combination of gutting the boxes and MAF screens free'd up some HP.
13.89 at almost 97mph with just that airbox mod, headers/flowmaster, and 2800 stall, all on stock 2.77 gears, street tires, and with 146K miles on the car which i believe is still the original motor, cuz when the tranny blew, it was at 140Kmiles and clearly was original inside.

and i do believe in the length of air has to travel = more effort/energy required to take it in.

think about straws........ suck in air or liquid thru a 3 inch straw and then a 12 inch straw and then a 30 inch straw, same diameter. its clear to see the longer the path of flow, the more energy it takes to suck it in.

same applies with TPI runners, the air travels a great distance so RPM range is limited.

it would be interesting to see if a speed density setup, stock TPI/motor using the factory TPI airbox vs. a regular cone filter attached to the throttle body. i wonder if that will change the rpm where peak power is made, and how much power difference there is as RPM'S go up and up. to me, it would seem that cone filter would make more power at higher rpms and might actually raise the peak power point abit since airflow travels a shorter distance.. this is assuming same air temperature


lol, could you explain the turbulence, 100mph toll booth thing? i never blew thru a booth before and wouldnt think it would cuz much problems in turbulence, but i am guessing it must be like when a mack truck flys by and you feel the force of the wind. :D

Yep, it takes atmospheric pressure to refill the cylinders. The less resistance to that process the more air that will get into the cylinders and therefore more horsepower.

Based on that criteria you would want the shortest air intake to the throttle body with the least amount of turbulance. The fewer angles the better. Short straight line being best and of the proper diameter. I have a 3.50" system on my car with the MAF being the restriction.

Thats why I don't believe a 58mm throttle body can hurt anything. You may not need one but I don't see the harm except for your pocket book. I chose to install one on my car.

I also believe in the cumulative effect as was stated above. Your flow will be somewhat less than the most restricted part. In my case the MAF. I took the screens out of my MAF in 1991 and have seen no ill effects. VIncentZ28 has had his out longer than mine with no problems. To each his own on the screen issue. Allen

I don't think anyone was suggesting that there will be a problem if you take the screens out...

... what's being suggested is that it is not ideal, and the screens were a design feature to smooth airflow (remove turbulance). I don't think that they would be there if they didn't serve a purpose.

I think I may have suggested it, but it wasn't my intent. I'm just saying that I don't think it helps OR hurts. I think it's WAY too unproven to be such a "first mod" that everyone does. Once you're into the hobby, you can make your own decision, but I don't think new kids that come here with questions about there new TPI should take out the screens. (I'm not saying anyone suggested it to anyone in this thread)


I agree. Again, like my previous concern, I think it should be an individual thing, NOT generic advice given to newbies on how to make power. ...and again, I'm not saying that anyone here IS preaching these mods, but you know there ARE people who do.

:doh: JK

OK, I'm from Jersey. On the Parkway, there's tollbooths every few hundred yards it seems like and some of 'em are barely wide enough to get through. If you scrape the side at 2mph while pulling out, short of a big scratch, no big deal, right? Now imagine blowing through the booth at 100. All ya gotta do is nick the side and you're toast. Or here's an even better analogy!!! Restrictor plate races in Nascar. 4 wide at Daytona, 185 miles per hour. One little bit of turbulance and ya got a 20 car pile-up. Now go four wide at 90 mph at daytona. Sure it's not as fast (not as much CFM) but it's smooth, no problems.

haha yeah i was just playing around... i get your analogy, but i admit, it took me alittle while... abit slow today


the 58mm throttle body issue would actually hurt performance if you dont need the extra air, basically the air velocity is hurt. going from a small tight higher pressure MAF region, to a bigger lower pressure region slows air down, which in return robs power and i guess makes the engine "work" harder to get the air it needs. or it doesnt get as much air as it could since the air is slower moving

now a bigger motor with greater ability to draw in air can get away with the lower velocity and uses the extra air provided by the larger TB to its advantage.

Well, that's the logic, but I think what 1989GTATransAm was getting at is that after the MAF, you've already slowed the air down enough to negate the "too much air" negative effect. In other words, the 48mmTB flows more than enough to have lost the pressurized velocity effect.

....and that brings me to another thought: for stock and mild TPI's, would a SMALLER TB actually help? Based on the idea that a 48mm TB can support X amount of air needs, and motor requiring less air would actually benefit, no? We all know that the TPI itelf creates a pressurized effect, and that's what produces the TPIs excellent torque. If a 48 is NOT the weak link in the system, that means that the TPI is not using the TB to create velocity. A smaller TB would just start the "tuned" port air velocity effect that much earlier in the airflow path.

...and here's more food for thought: What if someone made a MAF tubing that was actually a big venturi?

funny thing about those newer frequency MAFs.. the Mitsu Evos have problems with them. Don;t have the link but the board for them had a disscussion on how muscle cars/ harley/ basically loud sounds.. were stalling the cars out at idle :D

Installing bigger intake passages, to compensate for air density, cumulative effects, air travel distance and real world inefficiencies, must have diminishing marginal returns. You must get to a point where the wider air passages will not produce any increase in airflow. Beyond that point I am wondering if the wider passages would produce more turbulence as the air tumbles around in large passages and hurts air flow. I do not know I am just thinking out loud. I do not believe installing a 52 or 58 mm throttle body would hurt the induction system but I have seen nothing so far that says it will help a stock or mildly modified 5.0 or 5.7 liter engine. I have removed the screens from my MAF and have not experience any problems; however, I have no empirical data to indicate it helps air flow and engine performance. I read somewhere the screen help filter out particles that would collide with the wire in the MAF sensor and extend the sensors life. The screens may or may not smooth airflow much like an airfoil clipped to the throttle body does. All we do know is that more air can be pushed thorough the MAF sensor with the screens removed.

Maybe that is another point to consider. All the tests we have seen measure the maximum air that can be pushed through MAF sensors, throttle bodies, intake passages, etc. That is different than pulling air through via an induction system at less than capacity where air density, cumulative effects, distance, etc. come into play.

...this has been proven. It DOES smooth out airflow.

this is also true.

What has not been determined is even if MORE air can enter without the screens, DOES more air actually make it through? The PROVEN turbulance may actually hurt the flow of air. Maybe even with the turbulance, enough extra air may make it through to help. THAT is what hasn't been established.

dyno tests? check out ws6.com. a tpis air foil added 2-5hp.

5000/2 x 0.18 = 450 cfm.

Air intake occurs 1 stroke out of four (as you said), but only occurs once per every two revolutions (that's why I divided by 2, not 4).

450/8 = 56.25 cfm per cylinder, averaged over a revolution

I bolded that comment because you only get air intake during around half of a full revolution of the crank.... and to be slightly more precise, say 190 degrees out of 360:

56.25 *360/190 = 106.6 cfm avg flow during the actual intake part of the stroke.

The intake stroke is sinusoidal, so the actual peak airflow is going to be roughly 41% larger, so

106.6*1.41 = 150.3 cfm

That number represents the peak airflow during the intake stroke. And it's quite close to the peak stock unported value for 305 heads like the 187 casting. BTW I also assumed, as you did, 100% VE in the above. AT 5000 rpm the VE is only going to be 0.60 to 0.70 typically so the peak airflow will only be in the 100 cfm range. You could repeat the above, as I've done, using a higher VE (say 80% to 90%) for the rpm for peak torque, but the flow demand will be less because it's primarily driven by rpm.

You have the right approach, but I think you need to tweak it as I did in the above. I've done this before, I think here on TGO, but it's in an old post that I couldn't find. It's not perfect, but to make it more accurate would require using Matlab and that's over the top for this group. HTH.

Ramchargers has a product called the translator that allows tpi guys to run a late model lt1 or vortec truck MAF with a stock style tpi set-up. FYI:waveman:

Ok I can see that now. The connecting rods do not bolt to the center of the crankshaft. Rather they bolt to journels offset from the center of the crankshaft. So at this point the bottom of the connecting rods are moving through a larger circle than the crankshaft. While only 1 stoke in 4 is an intake stroke it occures at some degree less than in direct proportion to the crankshaft RPM. Thanks for explaining that.

So these heads are able to intake all that the engine can physically pull in. Why then would you need to port the heads or have bigger intake ports and valves?

Ok I can see that now. The connecting rods do not bolt to the center of the crankshaft. Rather they bolt to journels offset from the center of the crankshaft. So at this point the bottom of the connecting rods are moving through a larger circle than the crankshaft. While only 1 stoke in 4 is an intake stroke it occures at some degree less than in direct proportion to the crankshaft RPM. Thanks for explaining that.

So these heads are able to intake all that the engine can physically pull in. Why then would you need to port the heads or have bigger intake ports and valves?

THey have a website? How much?