Times thru the stock airbox.

[Turbo6Smackdown]

so then what do you think of using kirbans bigger inlet bell, with the compressor housing bellmouthed out below it. like this.

[/IMG]
Do you think it'll have any better flow rates?

 

[Turbo6Smackdown]

I got a question... if the stock inlet bell is the limiting factor, then why do the turbos breathe better, when one goes to a solid 3" maf pipe with a K&N cone filter stuck on the end? Wouldnt it stay the same if it was the inlet bell doing all the restricting?

 

[Turbo1dr]

I find it hard to believe that the stock inlet bell is the most restrictive part. I would agree that it would be restrictive if it was located anywhere else in the intake other than directly on and very near the inlet wheel of the turbo. Besides, it's actually larger than the snail housing.

 

[usetaboost]

SO what about purolator? Will that ever be tested? I know they make good fuel filters, what about air????

 

[A2000RICH]

SO what about purolator? Will that ever be tested? I know they make good fuel filters, what about air????

i'll do it sometime--------if you don't see it soon remind me........RC

 

[A2000RICH]

I find it hard to believe that the stock inlet bell is the most restrictive part. I would agree that it would be restrictive if it was located anywhere else in the intake other than directly on and very near the inlet wheel of the turbo. Besides, it's actually larger than the snail housing.

i know it may not seem intuitive but it doesn't matter what order you put them in------sometimes it makes things easier to understand if we deal in terms we are more familiar with and use analogous comparisions---------in a hydraulic system flow is equivalent to current in an electrical system------volume is capacitance------- springs are inductances-----friction is resistance------and pressure is equivalent to voltage---------remember that in a series electrical system current is constant throughout and voltage is dropped across each individual resistance-------changing the order of the resistances doesn't change the current through the circuit--------you could put the inlet bell first followed by the hose, maf, elbow, air box and snorkel and the flow would be exactly the same for the same overall pressure drop----------with one possible exception------the shape of the airbox may introduce nonlinearities if the air flow is reversed ..............RC

 

[A2000RICH]

I got a question... if the stock inlet bell is the limiting factor, then why do they turbos breathe better, when one goes to a solid 3" maf pipe with a K&N cone filter stuck on the end? Wouldnt it stay the same if it was the inlet bell doing all the restricting?

the answer is no--------the inlet bell isn't doing all the restricting-----it does most of it but since each part does some restricting any that you can eliminate always helps---------here is the issue------when you have one dominant restriction then it limits the other improvements to a great degree and they can never perform to their best.............RC

 

[HyperV6]

Thanks Richard for all the great info. What horsepower / e.t. limitations do you see for a complete stock airbox setup with an AC filter? I'm also curious if the aluminum plate Kirban sells that exposed half the air filter helps. If / when you test please let us stock appearing nuts know.

Thank you, Craig

 

[jwillettgn]

Richard, I believe you as I design, build, and test filters for a living. There are hundreds and hundreds of different media types to choose from these days that can really do an outstanding job of flow and filtration. Years ago I tested a paper filter and a K&N for a dirt track racer. We found the paper filter outflowed the K&N when new. We then tested a paper filter after a weekend of racing where it was really dusty and the paper did loose about 12% flow at the same DP, that weekend was not the norm and was a worse case. We did not test the K&N after a weekend of racing but have heard that they hold more dirt before losing flow. The dirt racer decided to change paper filters after every race rather than deal with the K&N. Alot of things need to be looked at when checking filters. Number of pleats is one, too many pleats are as bad a too few as they will be jammed together too tight and air will only flow through the tips.

Oh back on track, yes 12's can be done with the stock air box.

Richard, was that you at The Rock this weekend? I did not get a chance to talk to you if it was.

Jim

 

[Turbo6Smackdown]

I see... yea, i know of the pleat issue, as they went over that in oil filters as well. learned a good deal there. as far as our intake tracts.. so basically, if you want to do a cheap simple breathing mod first, it should be the inlet bell. anything else is a little less important I see. especially the k and n filter. good stuf here.

one more thing. what have you determined, if at all, about the turbulence, from the oil breather hole on the inlet bell. whats the flow/turbulence on it stock, vs that hole filled up with an aluminum rod and smoothed off. any tests on that? i know now, that no question is too anal to ask you, as you are more thorough than I previously thought. when you get some spare time, im pretty curious as to how it reacts with no hole. Also, tell me what ya think about the little ridge thats rolled into our stock up-pipes. I want to push a stock design (stock appearing anyways) to its absolute limits. If I can get reliable horsepower out of my little idea, I'll just leave it that way.

 

[Turbo1dr]

i know it may not seem intuitive but it doesn't matter what order you put them in------sometimes it makes things easier to understand if we deal in terms we are more familiar with and use analogous comparisions---------in a hydraulic system flow is equivalent to current in an electrical system------volume is capacitance------- springs are inductances-----friction is resistance------and pressure is equivalent to voltage---------remember that in a series electrical system current is constant throughout and voltage is dropped across each individual resistance-------changing the order of the resistances doesn't change the current through the circuit--------you could put the inlet bell first followed by the hose, maf, elbow, air box and snorkel and the flow would be exactly the same for the same overall pressure drop----------with one possible exception------the shape of the airbox may introduce nonlinearities if the air flow is reversed ..............RC

Understood. However, the inlet bell is actually a funnel shaped device that tapers down towards a smaller diameter hole of the turbo's inducer wheel. How can that be a restriction? I understand that if it was placed at the beginning of the air intake system that it would be a restriction since you want to keep the diameter of the complete inlet system as large or larger than the smallest diameter of the entire system.

 

[SloGN]

if that had happened i would not be able to post about it------i would be dead from a heart attack caused by total disbelief of everything-------even so you got to admit what i said is hard to accept-------i am reasonably confident that is not the case with the other stock location K&N filters on the market but how did they let the one for the GN slip by the testing dept---------were they just so confident about the results that they didn't do any comparison tests------in the last 20 years they have probably sold nearly one for every GN-------i don't think it fits anything else?????now that i think about it the in store tester that is so impressive always has a fram for a comparison-------anybody else seen the point of sale demo with the fan and the two filters with the floating ball??????------kinda makes me wonder????????????and makes me want to do some more testing---------this may not be as much agout K&N as it is about fram.................RC

Richard

The GN air filter will fit other brands of gm car's- The 85-88 2.8L fiero, z24 cavilier 2.8L with the air induction hood late 80's. I think that some of the FWD buick sedans used that same air filter as well.

but the air box on the fiero and the cavilier are round instead of squarish like the gn.

 

[UNGN]

The two biggest restrictions of the stock airbox is the lid outlet with the bolt clamp going into the elbow and the smallish box opening. The combination of the two flows like @ss.

Swapping filters in the box is like swatting gnats. You are talking only a couple .1's, max.

Replacing the throat bottleneck with a screenless LT1 MAF sensor, eliminates the restriction of the Stock MAF and completely frees up the flow. Night and day. Knock the bottom out and add a small cone K&N and it will run 10's, no problem. Compared to a 14" K&N and stock MAF, there was zero measureable performance difference at 11.50's @ 118+.

Note that this is on a car with a stock inlet tube and stock inlet bell, both of which are no where close to the restriction of the stock box lid or inlet opening.

As for the difference between a stock box and a modified box, at least .75 seconds and 7 mph difference, minimum, even on a stock/turbo injector/intercooler car. The more mods, the bigger the difference.

 

[A2000RICH]

Richard, I believe you as I design, build, and test filters for a living. There are hundreds and hundreds of different media types to choose from these days that can really do an outstanding job of flow and filtration. Years ago I tested a paper filter and a K&N for a dirt track racer. We found the paper filter outflowed the K&N when new. We then tested a paper filter after a weekend of racing where it was really dusty and the paper did loose about 12% flow at the same DP, that weekend was not the norm and was a worse case. We did not test the K&N after a weekend of racing but have heard that they hold more dirt before losing flow. The dirt racer decided to change paper filters after every race rather than deal with the K&N. Alot of things need to be looked at when checking filters. Number of pleats is one, too many pleats are as bad a too few as they will be jammed together too tight and air will only flow through the tips.

Oh back on track, yes 12's can be done with the stock air box.

Richard, was that you at The Rock this weekend? I did not get a chance to talk to you if it was.

Jim

yes------i was at rockingham----i was with a friend who wanted to borrow my trailer for his car to do some tuning in case he broke sometning-------i helped him build his engine, tranny and recently put a new gear and axles in the rearend for him---------guess he doesn't trust my work-----just kidding------about the filters------i had suspicion about dirty filters--------in fact when we did the tests i mentioned that things might be different after some "dirt" buildup------i remember we went around to find a dirty example and looked under the hood of several of my cars to find dirty filters-------but we weren't able to find any--------at any rate if absolute performance is the goal i see a new filter every few runs as pretty cheap compared to everything else we do to go fast-----------since you are in the area feel free to stop by if you find yourself passing nearby.....................RC

 

[A2000RICH]

fired up the flowbench tonight-------i was encouraged by how many folks seemed to be interested in the stock airbox-------some numbers to ponder--------and some test conditions--------all measurements are CFM of flow at 28 inches of water------
stock elbow with temp sensor- 793
empty airbox and elbow no snorkel- 475
empty airbox and elbow with snorkel- 572
empty airbox and elbow with kirban lower plate no snorkle- 799
empty airbox and elbow with kirban lower plate with snorkle- 781
full airbox and elbow with purolator filter w/o snorkle- 454
full airbox and elbow with purolator filter with snorkle- 534
stock inlet bell with open vent- 589
stock inlet bell with vent capped with rubber cup- 620
stock inlet bell smoothed (flashing removed) and vent filled flush with epoxy- 629

note:these figures are not corrected for hum/temp so they are only useful for relative values

let me know what you would like to see and i will do it in the next few days...........................RC

 

[Turbo1dr]

stock inlet bell with open vent- 589
stock inlet bell with vent capped with rubber cup- 620
stock inlet bell smoothed (flashing removed) and vent filled flush with epoxy- 629

Speaking about exhaust cut-outs...this goes to show that a exhaust dump may hamper flow of a exhaust system if you open it just like it hampered flow of the stock inlet bell.

 

[A2000RICH]

Speaking about exhaust cut-outs...this goes to show that a exhaust dump may hamper flow of a exhaust system if you open it just like it hampered flow of the stock inlet bell.

this stuff will surprise you--------things that seem like they should be always aren't when you flow them--------i could see how someone that spent lots of time with a flowbench mught develop a "feel" for how things really work but without one its a shot in the dark-------testing mufflers and exhausts is fascinating-------if there's anything you want to have compared feel free to contact me about it-------i'll do it for no charge------all you have to do is send it to me and i'll even pay to ship it back............RC

 

[INEEDAGN]

Speaking about exhaust cut-outs...this goes to show that a exhaust dump may hamper flow of a exhaust system if you open it just like it hampered flow of the stock inlet bell.

I will admit that's possible with a nice flowing aftermarket exhaust, but if you are ever in kansas I invite you to stop by and feel the difference between the original exhaust and an open dump. Stock stuff is awful restrictive. I'd change it but, well, it's the original stuff and I like to brag about how rust free my car is.

IMO the "best" set up is to have the exhaust branch out the side of the test pipe and have the dump at the straight end.

Test a big mouth cold air kit!

 

[Turbo1dr]

I will admit that's possible with a nice flowing aftermarket exhaust, but if you are ever in kansas I invite you to stop by and feel the difference between the original exhaust and an open dump. Stock stuff is awful restrictive. I'd change it but, well, it's the original stuff and I like to brag about how rust free my car is.

IMO the "best" set up is to have the exhaust branch out the side of the test pipe and have the dump at the straight end.

Test a big mouth cold air kit!

Yes, a dump on a restrictive exhaust system will improve performance...like you said.

 

[UNGN]

fired up the flowbench tonight-------i was encouraged by how many folks seemed to be interested in the stock airbox-------some numbers to ponder--------and some test conditions--------all measurements are CFM of flow at 28 inches of water------
stock elbow with temp sensor- 793
empty airbox and elbow no snorkel- 475
empty airbox and elbow with snorkel- 572
empty airbox and elbow with kirban lower plate no snorkle- 799
empty airbox and elbow with kirban lower plate with snorkle- 781
full airbox and elbow with purolator filter w/o snorkle- 454
full airbox and elbow with purolator filter with snorkle- 534
stock inlet bell with open vent- 589
stock inlet bell with vent capped with rubber cup- 620
stock inlet bell smoothed (flashing removed) and vent filled flush with epoxy- 629

note:these figures are not corrected for hum/temp so they are only useful for relative values

let me know what you would like to see and i will do it in the next few days...........................RC

What does the Kirban lower plate with a Filter flow? It appears you flowed it without a filter. Did you flow it with a filter?

Flow numbers are highly dependent on the input and output. The Elbow flowed 793, but was this with a bellmouthed venturi inlet or just straight hooked up to the machine? If a bellmouth wasn't used, the elbow might actually flow 1000 CFM since it is a middle component of a system and not acting as an inlet or an outlet.

Similarly, if you flow a stock MAF, you will conclude "this thing sucks", but if you put a 4" to 3" bellmouth on the front of it, it will flow almost 1000 CFM with no other changes. The bellmouth would simulate the airflow the MAF would actually see in the system, since very few of us run an open MAF.