Dual intake, Mafless tune... At least I hope

[04goat]

I'm finally pursuing a project that I've wanted to try since getting my GTO six years ago... I'm planning to run a dual intake. I could go on for half a page about the details, but they are moot so I'll leave it alone. But if you wanna know, ask.

Yes, I have sourced all the parts I will need.
Yes, I am planning on relocating my battery to the trunk to make room for this project.

In fact, over the last few years, during many daydreaming... I mean, brainstorming sessions, standing and staring under the hood, I have thought through pretty much every finite detail, and come up with a solution to every problem, save one:

I can't think of a way to run a MAF in this setup, given how close the throttle body inlet is to the radiator. After MUCH pondering, I've decided that going MAFless may be the easiest (and possibly even the BEST) solution.

I've searched the forums for posts regarding MAFless tuning of the LS1, and come up pretty empty-handed. But I know there HAS to be a lot out there... In fact, I found this post (referencing a post on THIS forum) on the ls1gto.com forums. It tells me a lot, but I'm still a bit wary...

I've read the debate and the heated pissing matches about whether MAFless is a good idea or not. I'm interested in hearing from naturally-aspirated LS1 owners who did such a tune on their own, and their experiences.

For the record, I've had my VCM for several years, but steered clear of the many fuel system possibilities. I am very wary about taking my only mode of transportation out of commission... After all, my 100-mile commute would take a LOT longer on foot!

All feedback, advice, testimonials, links to threads I must have missed, etc is greatly appreciated.

Thanks!

[detroit]

so you want to run dual Throttle Bodies?
there is a guy on performancetrucks.net, screen name DrX that is running dual TVS 1900 superchargers with dual TB's he might be able to help you out

[CarsonTech]

Running an SD tune isn't that bad. A lot of people do it on here. Although, it can't compensate for changes as well as a hybird or MAF only tune.

Now, as for the "dual intake" you want to install, do you mean an intake manifold that will except two throttle bodies? Or are you talking about splitting the air intake piping so it sucks air from two locations?

[04goat]

so you want to run dual Throttle Bodies?

...do you mean an intake manifold that will except two throttle bodies? Or are you talking about splitting the air intake piping so it sucks air from two locations?

I currently have the K&N FIPK which runs a single tube to the stock airbox location.

What I am trying to pull off is a y-tube at the throttle body which goes both directions, and then down through the body just behind the stock fog-light locations. The fog lights will be removed and the openings will become ram air inlets. It will look a bit like it does in this old photo from when I just finished mounting the bumper.

This example is an LT1 in a '55 Chevy, but it illustrates what I'm trying to accomplish (although the design in my mind will be much better on the eyes):



Now, as you know, the LS1 GTO throttle body inlet is much closer to the radiator/fan than in the old '55, so things will be tight even WITHOUT a MAF, and pretty much impossible (by my estimation) WITH the MAF. I have located all of the tubing, mounting hardware, grommets, clamps, etc that I will need. I can totally make this work, as long as I can figure out a solution for the MAF and the other sensor.

I'd love to do a fancy setup with a trick dual intake manifold, but that is way out of my price range. I'm going more for a mild-to-moderate performance increase, but a BIG increase in the "wow" factor when I open the hood.

There is another problem with this setup... There is another sensor mounted on the intake tube (vacuum?) that I will have to relocate. Does anyone know if that sensor will work ok if it is mounted within a few inches of the throttle body (where the two tubes join)? Or is there a way to just eliminate it? I am not even sure what it does exactly.

Now, by no means am I opposed to running a MAF. If anyone has ideas on how I could still use a MAF in this type of setup, I am all ears. But I measured the MAF, and even if I managed to mount it straight to the TB, the inlet on the MAF would be like an inch from the radiator... So, unless there is a way to run "dual MAFs" or a MAF that I can mount inside my tubing, then I don't see another solution besides eliminating it.

Thanks for everyone's time!

[BBA]

You could keep the MAF and gain about 30 RWHP by using the GMPP carb intake, with injectors in the bosses of course, a flat plate to mount the throttle body to, a 90º from the throttle body, then MAF, then split it to two airfilter pipes as you wish.

[EFI]

Why not go with a simple over the radiator intake like the vararam or the one custom made by svede? Seems like a lot of trouble mocking up such an intake. Also, it's not so much about air volume as it is air velocity and restriction. The stock intake tube flows pretty well, but it's got a tight 90* bend and that's where the real restriction is. Intakes over the radiator don't necessarily flow that much better, but the fact that it's a straight shot into the manifold makes them superior. Not to mention keeping the all important IATs down much better.

But if you get the design figured out, it won't be hard to tune for it without a MAF. As long as you have a wideband and tune your VE table correctly, you're all set. Heck I did my SD tune with just STFTs and it's damn near perfect (verified on a dyno with wb).

[04goat]

You could keep the MAF and gain about 30 RWHP by using the GMPP carb intake, with injectors in the bosses of course, a flat plate to mount the throttle body to, a 90º from the throttle body, then MAF, then split it to two airfilter pipes as you wish.

Yeah, I thought about such a setup. The site where I'm sourcing all the intake supplies carries parts to pull of such a setup. But, again, that is still a significant increase in the cost of the project... Plus, that would add a lot of height. Now, I know there's some room over the intake manifold, but I'm not sure if there is THAT much room.

It's definitely still on my "reserve" list of ideas, for sure.

[04goat]

Why not go with a simple over the radiator intake like the vararam or the one custom made by svede? Seems like a lot of trouble mocking up such an intake. Also, it's not so much about air volume as it is air velocity and restriction.

I guess I should share that I'm not a drag racer... or a racer of any kind. Drive fast? Hell yeah! Love speed? Duh, I have a GTO! But I don't care if my car is the "fastest in the south" (or even on my street!)... I mean, sure, I'm not going to turn away a performance increase, but ANYONE can buy an aftermarket Vararam or Svede or (whatever else)... I guess what I'm saying is, I'm either going to stick with the FIPK (which works great, by my estimation), or I'm going to come up with some crazy and unique idea that will get double-takes when I'm at a show or at the car wash or wherever and I open the hood.

Bottom line, I'm going for originality, here, as much as anything performance-related. If I wanted the same thing everyone else had, I'd be driving a Camaro or Mustang, and blend right on in with the flock.

[CarsonTech]

In my opinion, this may be a little overkill for your mods, unless you plan on going to get some better flowing heads and a bigger cam installed in the future. I don't think you aren't going to notice anything with it now, or even with more extreme engine mods. I don't think it's worth the trouble, personally.

Don't get me wrong, I like cool projects like this. If I were to do this, I would make sure there are no extreme bends and make sure to use the right material so heat soak isn't and issue. I would definitely find a way to keep the MAF.

[5_Liter_Eater]

If it's what you want to do then go for it. You should have no problem running an SD tune (MAFless). Before you start make sure your VE table is in good order with the current setup. Just disable the MAF by setting the MAF Fail High to 0 Hz and set P0103 to MIL on first error. Then drive around normally trying to stay out of PE and log fuel trims against the VE table. Copy and paste (paste special, multiply by %) the fuel trims from the scanner into the VE table on the tune, do some hand smoothing where there are large cliffs, flash and repeat until fuel trims are zero +-5. WOT VE tuning (not unlike WOT MAF tuning) will require a wide band. the process is the same but you disable closed loop and log AFR error against the VE table.

[JoeyJoeJoe]

If you wanted to use a MAF, is it possible to convert to a card style? They take up a lot less room and include that other sensor in your intake tube(IAT sensor).

[04goat]

I don't have much of a budget, and this project is more about the novelty and "cool" factor and "I made that!" factor than anything else. As long as everyone agrees that (if tuned properly) I shouldn't LOSE performance, and shouldn't do any DAMAGE to my engine, then I am leaning toward moving forward.

@5_Liter_Eater: So a WB is pretty much a requirement then? I'll have to research which ones others are using and add it to my parts list... Thanks for the tips! Along with some other posts RE: DIY MAFless, I have a fair amount of reference material.

Regardless of whether there is a power gain, I can say this for sure: It will look SWEET! I plan to have cone filters visible inside the fog light openings. If there is no damage or power LOSS, then I'm content with the improvement in the aesthetics. And if there is any power gain or improvement to throttle response, then even better!

If nothing else, if/when I can eventually scrounge several thousand dollars for new cam/lifters/rockers/springs/etc or new high-flow heads, it will be in place already to cram more oxygen into the mix!

(For the record, the motivation to do this "now" is in the fact that I am about to have my bumper refinished and properly mounted... So, now is the time to make the bumper mods... And if I'm going to do that, I may as well do the rest while I'm at it.)

[SSUte01]

I don't have much of a budget, and this project is more about the novelty and "cool" factor and "I made that!" factor than anything else. As long as everyone agrees that (if tuned properly) I shouldn't LOSE performance, and shouldn't do any DAMAGE to my engine, then I am leaning toward moving forward.

@5_Liter_Eater: So a WB is pretty much a requirement then? I'll have to research which ones others are using and add it to my parts list... Thanks for the tips! Along with some other posts RE: DIY MAFless, I have a fair amount of reference material.

Regardless of whether there is a power gain, I can say this for sure: It will look SWEET! I plan to have cone filters visible inside the fog light openings. If there is no damage or power LOSS, then I'm content with the improvement in the aesthetics. And if there is any power gain or improvement to throttle response, then even better!

If nothing else, if/when I can eventually scrounge several thousand dollars for new cam/lifters/rockers/springs/etc or new high-flow heads, it will be in place already to cram more oxygen into the mix!

(For the record, the motivation to do this "now" is in the fact that I am about to have my bumper refinished and properly mounted... So, now is the time to make the bumper mods... And if I'm going to do that, I may as well do the rest while I'm at it.)

Crack on, mate. There is so much bullshit out there about MAFless tunes not being able to compensate for weather/altitude/whatever, it is all rubbish, I have no idea why there is such a fear out there or such a need to 'clutch' the MAF. Don't get me wrong the MAF is a brilliant piece of technology and has many benefits, but on LS1s it has been shown literally thousands of times (particularly in Aus compared to the US for some reason) that MAFless tunes on Gen3s yield fantastic results. The only cavaet I would say regarding "compensation" is that all the provisions are there, it just takes a bit of work to get it spot on. There are plenty of threads out there about the IAT/ECT Bias.

Any Gen 3 that has a 75mm (3 wire) MAF I will remove, if it has a 85mm (5 wire) MAF I'll only keep it if owner wants factory look or retaining pod/intake pipe setup, if OTRCAI (which I always recommend btw) I'll ditch it and rewire the IAT.

Gen 4s are a different story where the difference is essentially negligle on a std cammed car. On a Gen 3, go out and try it for yourself, I have never seen a MAF tuned car make more than the same car tuned MAFless, and I have only seen power increases by going MAFless (sometimes very small sometimes a little more) and I don't know precisely the reason but on Gen 3s, MAFless always in my experience provides superior throttle response when tuned properly not that in theory they should but for whatever reason they do.

If the cost is low and the reward of trying it out for yourself is high, which it sounds as though it is then go for it. If for whatever reason you don't like it, then change back. There is no more risk associated with MAFless over MAF and you wont lose performance, you'll likely gain. If you don't believe me GM thought MAFless was okay from the factory on the LS1 on the HSV GTS and then the LS7 in the W427.

Don't believe all the myths, tune it correctly and you'll be rapt with the improvement of MAFless with the correct intake. Just confirm you have the 75mm MAF and cable throttle on yours??

Best of luck

[murphinator]

. If anyone has ideas on how I could still use a MAF in this type of setup, I am all ears. But I measured the MAF, and even if I managed to mount it straight to the TB, the inlet on the MAF would be like an inch from the radiator... So, unless there is a way to run "dual MAFs" or a MAF that I can mount inside my tubing, then I don't see another solution besides eliminating it.

Thanks for everyone's time!

could you possibly run a maf on one side and scale it somehow so it reports double what it sees on the one side with the maf - provided the 2 sides are identical mirror images of each other they should flow the same

just an idea , I have no knowledge to follow it through

[04goat]

@JoeyJoeJoe: I was wondering if something like that might be possible... But I couldn't find anything when I searched earlier. Are you familiar with any in particular?

@SSUte01: Dude! Thanks for the encouragement! That is basically what I needed to hear. Now, everything I've read on MAFless has talked about tuning and whatnot... but I haven't seen anyone mention "rewiring" anything... Can you expound on your "rewire the IAT" statement?

@murphinator: That is an intriguing thought... But I wouldn't know how to even begin pulling that one off. If anyone knows if this possible, and if so how to do it, I'm all ears!

[BBA]

Yeah, I thought about such a setup. The site where I'm sourcing all the intake supplies carries parts to pull of such a setup. But, again, that is still a significant increase in the cost of the project... Plus, that would add a lot of height. Now, I know there's some room over the intake manifold, but I'm not sure if there is THAT much room.

It's definitely still on my "reserve" list of ideas, for sure.

I don't think it would be very tall if you mounted the throttle body directly to a plate on the intake and used a low profile type 90º air tube adapter from an early 80's Buick Regal turbo (would probably fit the TB opening perfectly too)

Here is a pic to see the type of adapter I am talking about: http://home.flash.net/~rjgeorge/images/83engine.jpg

[BBA]

could you possibly run a maf on one side and scale it somehow so it reports double what it sees on the one side with the maf - provided the 2 sides are identical mirror images of each other they should flow the same

just an idea , I have no knowledge to follow it through

Bad idea...one air cleaner will get dirtier than the other, throwing off the calibration.

[04goat]

@BBA: At this point, I'm really leaning away from buying a new manifold and everything else that goes along with that. But I appreciate your idea! It's definitely interesting! If I circle back in that direction, I will certainly keep your post in mind.

[jakebdb56]

Just get one of the MAF cards similar to the one that VaraRam uses on their intake setups. You can cut, drill, and tap the MAF card right in front of the throttle body on your intake tube. If anything, you'll need to pinout your IAT sensor from your existing harness anyways and tap that into your CAI setup.

[04goat]

Ok, guys. I really appreciate all the feedback, from both sides of the debate!

I'm pulling the trigger... I just ordered the Y-Tube so I can start to measure and prepare the rest of the intake tubing.

I'm printing the tuning tips you guys provided as well as the other stuff I found, and am going to bust out the laptop and start getting to work on the tune this weekend. I'll have to order the parts one or two at a time since I don't know how all the angles are going to work out, so the fabrication alone will likely take a few weeks. But I'm hoping to make progress on my VE table in between yardwork and other crap over the weekend...

*holds breath, closes eyes, steps off edge*