bjankuski

FYI, To determine flow of an item it is checked at a pressure drop of 1.5 inches of mercury (inHg). That means it flows x amount at that pressure differential. That is a restriction and if you eliminated that restriction you have the potential to make more power. 1.5/29.92 = .05 or 5% restriction in the airflow. In other words if you are reducing you potential power by 5%. Other things to keep in mind is that every component in the system is additive and just because all items flow at least 500 CFM does not mean the system as a whole flows 500 CFM, more then likely the losses of every component in the system have reduced total system flow to 450 CFM. If you read the TPIS insider hints book you will see that they flow each item in the Corvette intake by itself and then together as a whole and the corvette intake system as delivered only flows around the 450 CFM mark for the TPI cars with MAF's. (but every part flowed more then 450 CFM) I am always looking for ways to reduce the intake piping losses into an engine, it has the potential to add free HP.

383vett

I'd forget the porting and go with a SuperRam or miniram for a meaningful gain.

bjankuski

Dt86

I know this is a porting thread but one of the biggest bang for the buck changes you can make on the early cars is to change your rear axle ratio. Especially if you had the 2.59 like I did.

aklim

Kinda weird. Have you ever tried running it as is and descreening and testing? I had a few Mustang friends that descreened the MAF and while it ran ok, it developed some odd characteristics at other parts of the curve. It is odd that similar MAFs run up to 3 tenths difference. 3 hundreds I can understand. 3 tenths is HUGE

Tom400CFI

I think the "problem" with descreened MAF's is in applications where there is a turn or elbow...something to meaningfully manipulate the flow, ahead of the MAF. The 'Vette's intake is pretty darn straight into the MAF.

Having said that, I descreened the MAF on my '96 Silverado 14 years ago, and it's run fantastic ever since. It has a 90* elbow right ahead of the MAF.

aklim

Seemed to notice it when 3 idiots decided to do it. If it were me, I'd let someone else do it and see what it does first. Well, monkey see, monkey do. One guy did it, 3 others jumped in and they all had reported some sort of issue, either idle quality changed or something while running. Again, you could be right. If it is straight, maybe it might be ok.

Did it change anything after you descreened? Better fuel efficiency, scanner readings improved, etc, etc? The 4 clowns didn't see any quantifiable improvement so I'm curious.

Tom400CFI

No subjective changes. No objective ones either. I bought the truck and installed UD pullies, shorty headers, replaced the stock muffler w/two aftermarket ones (Dynomax Super Turbos), descreened the MAF, installed a K&N air filter, and removed the "lip" on the TB blade.

Yer basic "retard mods starter kit". It's a truck, so I didn't dyno it or drag track it...and I couldn't tell any SOTP diff either. I felt the mods were mostly a waste of time/effort but they all together may have added some power. It's "always" (I did the mods right after buying it) gotten over 20 hwy, 17-19 around town, and pulled my boat better than it ought to through the rock mtns. So I don't see how it hurt in any way. But no meaningful data, one way or the other.

GREGGPENN

Here is a thread by [our] member WW7 that showed significant changes going from one MAF to another:
http://www.corvetteforum.guru/module...=13451&forum=1

So, Brian...At the very least, if you swap out a MAF (i.e., on the track), I'd think you'd have to reset the ECM and let it relearn fuel trims before running down the track again.

This thread provides the best MEASURED feedback on screened vs descreened MAFs. Note: I agreed with aklim on leaving the MAF alone for the OPs configuration. Mostly, this is because he is still near stock and doesn't NEED appreciable increase in (air) intake flow. When you get into strokers and FI, my answer isn't the same. Notice the biggest issue (with descreening) can be with low-rpm and tip-in response. My MAF is descreened. I also have a salvage MAF still with screens that I've considered swapping in for curiosity. However, I wouldn't do it w/o plugging in my laptop and monitoring the (BLMs) difference -- due to the thread linked above. Anyway...Here's SuperL98's thread on screened vs descreened MAF measurements:
https://www.corvetteforum.com/forums...post1584963813

Flow bench tests for TPI intake tract components:
http://www.gmtuners.com/flow/index.htm
(Note: I don't know that anyone has flowed a C4 airbox but TGO showed it's flow is about the same as a screened MAF....which means any thought of descreening needs to be coupled with airbox improvements.)

This is one of the threads that prompted more discussion into AIRBOX, MAF (tune) limits, and when there's an outright need (for a large build) to find/tune for higher air flow:
https://www.corvetteforum.com/forums...n-removal.html

Probably not relevant here but Here's the thread talking about when you exceed 255 with the MAF meter:
https://www.corvetteforum.com/forums...maf-units.html






Note to the OP: Sorry this is off-topic for your original question -- though it relates to overall changes for hp improvement (as you brought up).

As for the flow increases for porting a plenum (only), I know there is a thread or two on the topic AND I remember the changes were negligible on their own. Porting a plenum becomes a better idea with running it on top of large tubes and a big base. There are also "humps" just inside the plenum entrance that are worth looking at [removing] when going for a large (stroked?) TPI build.

None of this is a worthwhile effort when running at/near stock.

cv67

Against descreening the MAF
Some have done with no issue it but it screwed mine (guessing somehow some debris made its way past the filter and hurt some filaments in there) caused an intermittent lean condition which burned up a fairly new head gasket.
Sell the stock runners you cant do anything with them. Taking that little lip out does nothing.

Plenum...if you can DIY or cheap wont hurt you wont feel anything either

Nice gains to be had with the base however most shops if they are honest with you wont touch em. Too much work needed to get any gain

If youre stuck on the long tube thing as said the FIRST is the way to go.
If youre not just put a shorter runner intake on and make it easy

aklim

I disagree with that. After all, the mesh isn't so fine it will stop anything that your filter won't. The last time I looked at one, the only way it can do anything is if you run it without a filter and that debris scores a lucky hit. I tend to believe it more if you say that the measurement was screwed up which caused the lean condition than debris hit it and changed the value at certain points only.

cv67

thats what its about debris. Takes nothing to hurt a filament and change your reading.
unfortunately I didnt know....1 owner lots of reciepiepts, nice shape hack job labor turned out. lEarned the ahrd way. think I spent a yr bugging ol Jim and Sun for help. ran great then- bam....H.G.
Simply not worth any type of gain ran like any other stocker with Catback did thats all.

Corvette40

If you have the time. Added aluminum over an Edelbrock manifold mounting pads and bored the hell out of it. Also removed half the material from a set of SLP runners. Broke through in a few places and had to repair. Plenum was also matched to the runners. 320hp to the wheels with MAF. I'll post the dyno when I find it. Just dynoed the car again and swapped between screened and de-screened MAF. Lost 5hp going to a new screened MAF.

Motor is a 355 Vortec 4 bolt main block, forged two relief pistons and rods, AFR 195 heads with 7/16 studs, 1.6 roller rockers and Dyno Dons headers.

Next is aSuperram install and speed density conversion.