larger mass air flow pipe?

[Rahob]

Hello, forgive me if I'm asking a question which has been asked many times, I've tried searching every word variation of what I'm looking for, but not finding a direct answer. I'm assuming my answer is yes, but would it make a difference in the long run regarding my build.
I have a mostly stock 86 GN. I know it's bad not to have a "goal" time to shoot for, I have mite of a "parts list" to shoot for and whatever time I end up at, great. Future goals, 3" rjc exhaust and down pipe, test pipe, stock stretch intercooler, ta headers, hot wired fuel pump, slightly larger turbo (something that looks like stock) chip. No plans to open up the engine. Now the question, upgrading the maf sensor and pipe. I really like the 3" cold air intake kit with filter from GN1 performance and I would use a ls1 sensor, would I see any gains or would it be completely unnoticeable finding a design to change the pipe from 3" to 3.5"?
Thanks for reading all that
-Robert

 

[PSID6]

I have the 3" CAI with a LT1 maf and the car runs noticeably smoother over the stock maf. As far as seat of the pants difference I did not see any.

 

[laws69cars]

I have a 3.5 and agree with (PSID6) not a huge difference just a bit smoother.

 

[Rahob]

Thanks for your input!
So you think having that setup with 3" pipe, 3" lt1 sensor to a cold air inlet, (my version of colds air is a inlet behind the headlight, near where stock air inlet is) really would have no "noticeable" gain as having a 3.5" pipe from turbo through the ls1 sensor to 3.5" pipe again to inlet? ..... Given a very mild build like future plans.
-Robert

 

[Rahob]

Laws69cars, sorry, skipped right over your post. Thank you. I figured, plus since my long term goals are not so extreme, I didn't think it mattered all too much. Or at least not nearly as important as the diameter of the exhaust side of the story. Thanks!
-Robert

 

[earlbrown]

You'll see a gain either way just for getting rid of the stock MAF. They just suck compared to the more modern MAFs.

As far as the pipe size you won't really notice a difference between the 3" and the 3.5". Now going up to a 3.5" MAF will give you quicker spool and slightly better throttle response.

The reason is that a 3" LT1 MAF only has around 64% of the flow area of a 3" pipe (I can't recall the exact percentage, it's been a while since I did the measurements). The 3.5" LS1 units have a flow area in the 80's% of a 3" pipe.

Personally I love the way a 3.5" pipe looks with an LS1 unit on it. It just looks 'meaty' hanging off the turbo.

It could also be perception, since it just looks bigger and I've seen solid 3" pipes on these cars for decades.

Not the best shots to show the difference, but you can still tell the 3" looks small by comparison.

 

[Nick Micale]

...... Now the question, upgrading the maf sensor and pipe. I really like the 3" cold air intake kit with filter from GN1 performance and I would use a ls1 sensor, would I see any gains or would it be completely unnoticeable finding a design to change the pipe from 3" to 3.5"?...........

We recently did a dyno test on a GN that was basically stock but it had an open exhaust and no air cleaner.

After the SD2 chip was dialed in with a few pulls the MAF was left in place even though it was not working. I asked for one more pull w/o the MAF in place, and at WOT, about 5500 RPM, it registered an additional 14 HP.

This is way beyond the RPM seen on the street and the 6-7 HP gain in mid-range would not be noticed in normal or "spirited" driving.

If you add a cold air intake system this will kill more than the 14 HP possible gain due to additional bends and tubes which will restrict airflow. This has also been documented with dyno pulls on some NHRA cars we were tuning, and it was about 12 HP less w/o the system.

The reality of a street GN with moderate performance mods if they are done properly is that you can easily have more HP than you can use, as traction becomes the issue even with sticky tires!

 

[bison]

All the dynoing I've done over the years indicates that the MAF has to be a significant restriction point for it to show a worthwhile power gain. Usually it becomes such a restriction it raises the drive pressure required to achieve a certain pressure ratio and hampers the mass flow potential of a turbo. Of course the better the match of wheels and the less hard they are run the less the MAF restriction will show up. With a 60-1 and P trim I was consistently around 465whp with boost around 25psi with the wastegate bypass blocked using a single screen stock MAF. I later switched to XFI and was easily able to have higher pressure ratios and had to waste a lot more exhaust energy to keep boost in check. 510whp was the norm and boost was in the high 20's. The car later went 10.61@127.85 with that combo with boost around 30psi. Once the stock MAF was removed it knocked the spool time down a lot and also drove into the converter a lot harder a lot faster. Exactly what's needed for fast quarter times. With that said if your engine is capable of more than 50lbs/min you will likely see a much larger gain with a larger than stock MAF and more of a gain if you are high on wastegate tension. Beware that if you previously had a stock MAF and had the wastegate tension really high you better back it off and be careful on your first hit. I didn't log exhaust pressure back then but I am sure it was very high prior to removing the inlet restriction. Running nearly 130mph with a non adjustable chip through a 1 screen stock MAF many years ago using a 6776 makes me wonder what that combo could have ran with speed density if I could have fed it. 135+ without a doubt.


BPE2013@hotmail.com

 

[TurboTnZ06]

Yeah I went 130.8 mph in the 1/4 on my stock maf and tube with a 9 inch K&N on the end of it. Both screens in the 25+ yr old maf too. I did one back to back test, full stock 87 air intake system, ran 11.2 @ 117, then put my 4 inch intake and LS7 maf on, went 10.6 @ 128 or so, of course it gained a ton of boost with no other changes to my setup.

 

[Rahob]

Earlbrown, thank you. I failed to even think about the flow area of the sensor. That would make having a larger pipe pointless, but I do agree, it looks much better. I don't know if it just on my end, but I couldn't see the pictures you added in your post. For some reason I was not able to even pull up this site most of the day yesterday.

Nick Micale, so regardless of how important having cooler air is, the additional bends in extra tubing take precedence over temperature? I understand that adding bends adds a hypothetical amount of straight pipe, I just assumed, that would be for the "push" side of a setup. (This assumption is from my basic knowledge of direct vent hot water systems) in any case, it would be most valuable to have as straight a pipe as possible to the with a cone on it concluding in the area where the vapor canister is, and moving that to the frame rail? A concern i have read about in the past, which I thought was another benefit for the cold air system, is that the sensor was mounted in the middle of pipe sections, not directly behind the cone. I read with it behind the cone the incoming air is very turbulent, which could mess with the sensor readings. Is this something I'd have to worry about?

Bison and TurboTnZ06 thank you very much for your input. It's great when people are able to document little things like this. Us newbies rely on a lot of that!

Thank you very much for all this input!
-Robert

 

[vader87]

This is my opinion so take it as you will. A "cold air" intake on our car has minimal gains. The air gets compressed so it is heated rather quickly. This is why we use Intercoolers, to cool that charged air down a bit.

Before you spend all that money on the Maft and a translator, seriously look into a SD2 chip, power logger and wideband (you will need the power logger and wideband anyway if you wanna put down big HP numbers). Yes it can be expensive but YOU can tune your car and have NO MAF sensor. I run Speed Density and I will NEVER run a MAF sensor again!

 

[bison]

This is my opinion so take it as you will. A "cold air" intake on our car has minimal gains. The air gets compressed so it is heated rather quickly. This is why we use Intercoolers, to cool that charged air down a bit.

Before you spend all that money on the Maft and a translator, seriously look into a SD2 chip, power logger and wideband (you will need the power logger and wideband anyway if you wanna put down big HP numbers). Yes it can be expensive but YOU can tune your car and have NO MAF sensor. I run Speed Density and I will NEVER run a MAF sensor again!

I agree but 95% of the community has no idea about tuning


BPE2013@hotmail.com

 

[Rahob]

Thank you Vader87 I will look into that. Like Bison said, I am adding myself into that 95% at this point since I don't know much of setting up speed density besides that it is a measure of manifold pressure.
I didn't think about the intercooler earlier. It makes sense now, even if I can get air that's a "few" degrees cooler initially, the compression process just heats it back up regardless.
Thanks
-lotsa-questions-rob

 

[toomanymodz]

Old thread revival. I've decided to go SD2. I'd like to ditch the MAF and 3 inch pipe and run a 4 inch pipe in place of both pieces. I tried searching but couldn't find anything. My turbo has a 4 inch inlet, and I'm running the 'tinman' cold air setup, and I believe it's 4 inches as well. It'd be nice to have a 4 inch inlet pipe that will work with this setup. Suggestions?

 

[Nick Micale]

[QUOTE="toomanymodz, post: 3592531, member: 31964.............. My turbo has a 4 inch inlet, and I'm running the 'tinman' cold air setup, and I believe it's 4 inches as well. It'd be nice to have a 4 inch inlet pipe that will work with this setup. Suggestions?[/QUOTE]

I am just finishing a GN with fresh engine install, and your 64/66 turbo may have a 4" flange, but only about a 2"+ inlet air opening like the turbo on this GN. It is the inlet size and compressor wheel that limits the amount of inlet air.

Unlike a N/A engine, the turbo will suck in air, which is why N/A use as large an intake as possible from pipe to throttle body and they resort to larger ducts and TB to get as much air flowing in as possible.

The 4" custom bent inlet pipe the customer supplied is in the trunk of the GN as it will not "weave around" the alt, and not even come close to a good fit.

With the 3" metal MAF pipe I installed, it still required a 1" plenum spacer to raise the throttle body and IAC for all these items to clear and have no interference.

You already are introducing a lot of restriction in the air intake with the bends and extra hose/piping as we have seen up to 20+ HP loss when dyno testing with extraneous inlet piping. In one case removing a simple short plastic tube inlet with a 60 deg. bend from the turbo was worth 12 HP.

For the best possible configuration of the turbo for air inlet and exhaust out, we found this a simple set up!

 

[vader87]

Old thread revival. I've decided to go SD2. I'd like to ditch the MAF and 3 inch pipe and run a 4 inch pipe in place of both pieces. I tried searching but couldn't find anything. My turbo has a 4 inch inlet, and I'm running the 'tinman' cold air setup, and I believe it's 4 inches as well. It'd be nice to have a 4 inch inlet pipe that will work with this setup. Suggestions?

Mark at buickgn.com has them.

 

[toomanymodz]

Great info! Thanks a bunch. Getting rid of the stock MAF should be worth a couple of MPH. Don Cruz is finishing up an engine for me. I'll be installing it next year. Gotta get the car ready for the new engine. Figure I'll experiment more with my current combo.

 

[GNVenom]

Check out this video. In it, RC shows flow restriction numbers with various configurations. Interesting to look at: