H 4" inlet housing vs ordinary 3" inlet housing

[Blazer406]

That's basically what I've been running for a few years, using a 3" LT1 MAF ...............but I gained about 1.5-2 psi boost and just noticeable quicker spoolup on a Limit ptrim GT67 plain bearing turbo just from moving the maf and changing the inlet hose from 3" to 4".

Looks like the boost pickup.... tells us that without a doubt... on your car.... that moving the 3" LT1 MAF meter... from the suction side.... re-locating it to the up pipe.... was less of a restriction.... even though the same air would go through it in both locations.... The fact that you picked up 1.5-2 psi boost.... meant your turbo was a little more efficient.... and if you cut the boost down 1.5-2 psi .... to be at the same boost as you were at prior to the swap.... you would likely make more power... at the same exact boost.... cause the turbo was actually not having to work as hard to achieve the same boost....

Am I making any sense....

At least this is how I see it....

 

[Blazer406]

I was gonna do the MAF in the up pipe but think about this. If you take a straw and blow into it, it takes more force and psi to blow air then to suck air threw. Just a thought.

Maybe the straw and pump analogy I was trying to portray was a poor choice. I get your drift.... but Carl's findings IMHO point toward the up pipe as being easier on the turbo.... making it more efficient when coupled with a big @ss pipe on the suction side...

 

[Underboost]

Looks like the boost pickup.... tells us that without a doubt... on your car.... that moving the 3" LT1 MAF meter... from the suction side.... re-locating it to the up pipe.... was less of a restriction.... even though the same air would go through it in both locations.... The fact that you picked up 1.5-2 psi boost.... meant your turbo was a little more efficient.... and if you cut the boost down 1.5-2 psi .... to be at the same boost as you were at prior to the swap.... you would likely make more power... at the same exact boost.... cause the turbo was actually not having to work as hard to achieve the same boost....

Am I making any sense....

At least this is how I see it....

Yes it makes perfect sense. Wow that's cool!!!

 

[cstavro]

Just wondering? Why would you have a 4'' after the 3'' MAF? Aren't you loosing air velocity? I have a 4'' tube intake with a 4'' to 3'' cone reducer that speeds up the air then stays the same size 3'' all the way to the turbo. I ran a 6.39 @ 109 with that set up.


Blazer406 I was gonna do the MAF in the up pipe but think about this. If you take a straw and blow into it, it takes more force and psi to blow air then to suck air threw. Just a thought.

a specific pressure differential will cause a specific amount of flow in a pipe...regardless of which way the differential is. what you're experiencing is your lungs are stronger at blowing than sucking. therefore you create a higher delta P, more flow, and more resistance while blowing.

it is correct to say that a maf sensor represents a smaller % area in a 3" intake than a 2.5" intermediate pipe...and hence less restriction. drag is related to density...putting a sensor in the up pipe will increase resistance vs the intake @ atmospheric. imo

re the original post, 3" intake can handle ~600 hp. imo you won't see worthwhile gains with a 4" intake.

 

[cstavro]

Looks like the boost pickup.... tells us that without a doubt... on your car.... that moving the 3" LT1 MAF meter... from the suction side.... re-locating it to the up pipe.... was less of a restriction.... even though the same air would go through it in both locations.... The fact that you picked up 1.5-2 psi boost.... meant your turbo was a little more efficient.... and if you cut the boost down 1.5-2 psi .... to be at the same boost as you were at prior to the swap.... you would likely make more power... at the same exact boost.... cause the turbo was actually not having to work as hard to achieve the same boost....

Am I making any sense....

At least this is how I see it....

the same mass (lb/min) of air goes through the whole intake. it goes through the 4" pipe at atmospheric pressure. since the turbo compresses the air, it takes up less volume, and is happier with a smaller diameter pipe on the outlet. the gt67 likes a 4" intake. that's why the turbo liked the 3" maf on the outlet rather than on the inlet. hth

 

[ijames]

Blazer, I lied a little - well, had a slightly senior moment. Now that I've had time to think about it I moved the maf back when I had my PT54 3" inlet turbo. I went to the local track on a Friday night, ran a pretty normal for me 109ish mph with the normal setup - 3" hose from turbo to lt1 maf in stock location, 3" hose to elbow behind lights, 3" outlet cone filter. Then the next day I moved the maf to the intercooler up pipe and used a piece of 3" steel tubing in place of the maf, so the only thing that changed was the maf. Picked up 1.5 psi or so boost and a little bit faster spool but this is all with 93 octane and I got a little knock so I had to turn the boost back down about 1 psi but I figured I should still see a gain from the better efficiency. Went back to the track the next Friday, weather was similar, and I maybe picked up 1 mph, if that (my et's aren't consistent but mph usually is). I was disappointed not to have picked up more. Then the next day I put on the 4" inlet 67 ptrim and 4" hose to 4" elbow to 4" outlet cone filter, and after some tuning added another 1-2 mph at the same track within a few weeks so again, pretty similar weather, with maybe 1 psi more boost than I could run with the 54 on 93 octane. I think I posted this either here in the turbo forum or in the tech forum back then if you want to see if I included more details. Of course right now my engine is out so I can't repeat any of this.

Turbos are all about pressure ratios, so you want the highest pressure you can get at the inlet so you want minimal pressure drop through the intake plumbing. I think that any gains in velocity you might get with a cone reducer and keeping 3" hose between maf and turbo would be overshadowed by the reduced pressure drop from going to 4" inlet tubing. Course, without actually getting out a water manometer and doing some testing, that's just my opinion , but that increase in boost had to come from somewhere.

 

[Blazer406]

.......Course, without actually getting out a water manometer and doing some testing, that's just my opinion , but that increase in boost had to come from somewhere.

That increase in boost is exactly the results I would expect if you reduced the restriction on the inlet side of the turbo.

I saw an increase in boost about 1-1.5 psi when I installed my TH 3" DP with integral elbow... and a test pipe.... like you... that increase had to come from somewhere....

Then I took off my stock MAF meter... with stock MAF hose... with 3" K&N on the end of the MAF meter... and replaced it with a 3-1/2" MAF pipe and LS1 MAF meter and translator... and a 4" big mouth cold air kit.... and I picked up 1-2 psi again.... like you... it had to come from somewhere.

These gains also came using a stock turbo and inlet bell....

I think the larger the turbo... the more well defined these gains would be....

I also believe this directly correlates to the actual compressor wheel speed.....the reduced restriction.... allows the turbo to make the same boost at a slower compressor wheel RPM.... which enhances efficiency......

 

[Missouri T]

I just installed the Full Throttle 4" with the new Mass Air Meter last week.

Here are some of my findings and thoughts.

Boost Improvement:
I took my daughter to school in it this morning (nice and cool outside) and had just under 17 lbs. of boost, whereas the old 3" tubing/stock mass air/14" cone filter was 15.
The rate of boost climb is improved measurably.
Whereas before if I gently rolled into the throttle it would go to maybe 2 lbs. boost and start climbing.
Now it immediately shoots up to 5 lbs. and climbs MUCH faster.
Seems my PTE-51 likes the inlet restriction elimination.

Comparison:
Visually comparing the stock Mass Air with the new 4" is amazing.
4": The only "restriction" is a 3/16" wide by 2" long "stick" in the airflow.
3": Smaller-than-3" actual inner dia. and screens compromising flow to the turbo.

Why did I go with the 4"?
I was going to do an LS1 3 or 3.5" but thought the 4" upgrade and the latest-and-greatest mass air meter would easily take care of any future upgrades.

Present status?
Right now, my 6.24 Translator, TT chip and the 4" arrangement aren't playing well together-erratic idle, lean tip-in, erratic O2 readings.
I'm dying to get that 6.25 installed and get things tuned and straightened out.

Sound:
And let's not forget the sound....OH the sound of that 4" system is like no other. Under throttle, you'd think the car was jet-propelled.

If anyone has questions, don't hesitate to e-mail or PM me.

 

[bison]

Does anyone have an actual number they can post before and after on the same day in the same conditions with a/f corrected to a baseline of around 11.4:1? Ive always run the stock MAFS and havent noticed much of a performance loss in cars going under 125mph with bigger MAFS. Theres no doubt it is one hell of a restriction on a 600+hp engine. The time i dynoed my blue car (559/706) the inlet hose got sucked toward the compressor housing like an accordian. I always wondered what the gain could have been removing the MAFS and changing nothing but the fuel to get the a/f's back to where they should be. There is one thing that is certain and that is that it effects spoolup. You can actually hear, feel, and see it on the boost gauge when you nail the throttle. I just have a hard time thinking it will gain more than a couple mph at best with a bigger MAFS before the compressor inlet. Ive gone 128mph in a friends car well over 3700 lbs and ive gone 126mph easily at 3600lbs in 80 degree humid air at 24.5psi with the stocker with one screen in the stock location. I never got drag strip times/mph with the engine configuration that was in the blue car but it was considerably quicker than the black one in my sig. I was running up to 27.5psi and 9.0:1 compression on a fresh engine. It would have gone over 130 mph with the stock MAFS and 1 screen.

 

[wbrophy]

This is old news but if I remember right Red A. picked up 50 hp the minute he changed from a "completely gutted" oem maf sensor to his 4" maf setup.

 

[bison]

This is old news but if I remember right Red A. picked up 50 hp the minute he changed from a "completely gutted" oem maf sensor to his 4" maf setup.

I say no way. That would be nearly 3.5mph in my case and my MAFS has 1 screen still. I dont see that happening.

 

[vader87]

IMO, this is when "Bigger IS Better". I do not have numbers to back it up, but I noticed a huge increase over a stock MAF. Spool up is much quicker and you can actually hear the difference. I run the MafPro, Gbody pipe and Tin Man cold air kit.
My old set up:

The New:

 

[hemity]

This is great thread. I was at Etown yesterday for buick performace weekend (great racing weather) and had seen a couple of the tin man cold air systems (nice)and a good amount of 4.0 inlet pipes with zo6 ,ls1 or lt1 MAFs even 2 stockers. Set ups ideas seem to be all over place.
I noticed 3 guys had 4.0 or 3.5 inlet turbo bells one was on a stock turbo. Who make these ? years ago it was bowling green customs.

 

[bison]

This is great thread. I was at Etown yesterday for buick performace weekend (great racing weather) and had seen a couple of the tin man cold air systems (nice)and a good amount of 4.0 inlet pipes with zo6 ,ls1 or lt1 MAFs even 2 stockers. Set ups ideas seem to be all over place.
I noticed 3 guys had 4.0 or 3.5 inlet turbo bells one was on a stock turbo. Who make these ? years ago it was bowling green customs.

What et's were the cars running with the different set-ups? Did you ask the owners the actual gains that were found after replacing with the new MAFS? Ill have some info soon when i get my translator back. I think a lot of guys are upgrading simply because their stocker failed and they cant justify spending $100 on a used unit that may not last. They are not looking for or expecting a big gain. If the car is going under 125mph in the quarter the gains will be minimal and the money should be spent elsewhere unless the stock MAFS failed then it is worthwhile to upgrade.

 

[hemity]

I didnt have chance to really mingle do to having my wife and young kids being with me walking around. One guy from canada had a 4.0 zo6 set up on a worked stock turbo and motor .He said he runs in some super stock type class. That car was run into the 10s.
I do agree that people are changing over for the reliability and peace of mind.
I would say almost 1/2 of the car I saw are no longer running the stock MAF.

I do believe the the stock MAF set up with a cone is Choking the turbo to a point on cars running 19psi and over . May not need a 4.0 MAF and inlet tube. But better then stock I think would be a gain .

 

[Blazer406]

....... One guy from canada had a 4.0 zo6 set up on a worked stock turbo and motor .He said he runs in some super stock type class. That car was run into the 10s.
....

I'd say "worked stock turbo" was pretty loose.... probably was a TA66 LOL.... might look stock from the outside.....but far from it on the inside....

Sorry to get off topic.....

 

[hemity]

Just telling you all what i was told. All and all the car was completely a street looking car with AC ,no alky and nothing looking to nutty under the hood. That Is pretty impressive to be running in the 10s in my opinion.(Sleeperish)

Does anybody know if there is a company that make the larger turbo inlet bell . 3.5 or 4.0 ?

 

[TurboDave]

Answer: To get me by for now. Eventually, I will be going with a T-Pro setup and will eliminate the MAF all together.


Patrick

And it will blow you away!!