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Intake idea

Posted: Thu Nov 23, 2017 6:44 pm
First off... Happy Thanksgiving everyone! Now, on to my idea. This is for the 2.8-3.4 V6 crowd, a Helmholtz resonance intake. I'm not sure how many of you (if any) are familiar with what that is, so I'll explain it as best I can. Basically it is an intake that changes shape internally to keep the air moving at higher speed at different rpm ranges. The result is not necessarily more power, but, instead of having a single peak you move the peak around a little bit, it actually moves the TQ lower and higher in stages. This is not for the "just stick a 3.8/LS/572bb in it crowd," it's also not VTEC for your Chevy, this is for NA only V6 and someone adventurous that wants to experiment. That said you should feel a difference, you definitely notice a lack of power or bog if a solenoid fails. It is something I believe can be adapted from v6 Mazda engine, or maybe someone crafty could refine the idea better. I just want to put the idea forward. I have no idea about hood or strut bar clearances.

The stock Chevy V6 intake is one box (?) with 6 runners, TB at one end. The Mazda intake I'm referring to has 2 intake boxes (engine side of TB, that look like 1 box,) 3 runners on each box. There is a TB at one end, and a runner like tube at the other end of the intake with a valve that opens and closes connecting the 2 intake boxes. There is a second tube in the middle of the intake also connecting the 2 intake boxes with a valve that controls.
At low rpm, the valves are closed, all runners pull air from the TB side. Simulating a longer intake path.
At mid rpm the far valve opens and air gets pulled from the TB but also can be pulled from the far and the other box. Shortening the path to the runners.
At high RPM both valves open and air can be pulled from the TB, far end and middle to feed all the runners a larger amount of air faster.

There is also air getting pulled in all directions sawing around the intake back and forth, getting pulled down runners until the valves shut, at which point the air slams into the back of the intake valve compressing and then springing back up the runner, back into the intake. That air bouncing back gets used to help charge a runner with a valve open. At different rpms the air spring effect changes, is less or more effective, this is why vlaves and changing the shape works. This isn't theory, it works.

Both valves are vacuum operated by solenoid by the ECU. No biggie there are aftermarket switches, called window switches, that can be used and set to open and close these valves (with some JY solenoids,) based on rpm with whatever computer you have. You'd have to find the rpms that work best for you, and whatever combination you have.

The short of it. Cut a Mazda KL v6 intake at the runners in a way that it can be mated to the bottom part of the Chevy V6 runners, weld together or use a bunch of couplers. The Chevy intake sits in the V, whereas the KL intake (there are 4 different ones,) hangs over the rear valve cover. It's really tough trying to get an idea through pictures. From project 91 "SS" 3400/5spd engine bay pic with engine and strut bar it looks like there is room.

Runner spacing is even on the KL and looks offset on the Chevy I don't know if that makes it a no go or not, maybe it's close enough to fudge. I'm thinking 2 cuts at an angle to match up at the longer runners. There may also be more of that fudge room considering the OHV covers probably sit lower

2 of the KL intakes have oval runners, the other 2 have square runners. Oval would probably match up better, those are easier to find. The 2 oval port intakes also work better for lower rpms, which would probably work better with 2 valve engines. KLs are 2.5l v6, the oval port ones (intake heads) make 164hp 160tq or 170hp 160tq. Stock TB is 60mm, 65 can be fit, hourglassing can be done, and possibly twin tb from a Mustang can be adapted or fit. But the best of all the intakes makes 200hp, 170tq NA I believe still using a 60mm TB. Supplying enough air shouldn't be an issue with these intakes, any can be ported to support 200 NA. Not familiar with the Beretta's TPS, idle air, or egr setups. Worst case adapt a Beretta TB to fit. Anyway, I've written a novel here, hopefully a good read. I have a video that shows all 4 intakes and can probably give measurements or show specific angles if someone is interested in that information. Headphone warning at the end, last 5 seconds or so!

Re: Intake idea

Posted: Fri Nov 24, 2017 1:34 pm
by GT_Indy
I don't know if the intake is a direct swap, probably not, but the GM 3900 v6 (Code LZ8/LZ9) has a variable length intake manifold system built in with variable valve timing on a pushed design. I wonder if its easier to make an adapter plate of some kind and swap the intakes if its possible.
The only thing I'm wondering is if it would give any noticeable gains. I believe GM dropped the variable intake stuff from their designs.

I am interested to see what you come up with if you adapt a variable intake to a gen3 v6 or similar. Would be fun to see the before and after dyno results.

Re: Intake idea

Posted: Fri Nov 24, 2017 11:29 pm
Didn't realize there was a GM variable intake. Might work better if the spacing is already accounted for. GM could've dropped it for cost cutting or complexity with harder to quantify benefit for people just buying passenger cars. I can tell you it works, when it doesn't, it feels like it takes forever to get into the powerband.

A lot of noobs disable the system in search of higher peak numbers which they may achieve, (only if they take the valves out of the intake, most only tie them open,) but they'd get their butts handed to them by a fully functional car. I also currently have a mismatched ECU intake combo. The only real fix for that is the window switches I mentioned earlier. To set the resonance timing to the correct rpms. Mine is only off by a few hundred RPMs so really it's not a big deal, the ECU I'm using has a MAF and can deliver more fuel at WOT so literally 12-15 more hp and tq. It just means I feel them switch over more. If I switched to the proper intake to go with that ECU I'd lose 5hp, so I think it's better the way I have it. The one correct IM for that ECU I have was a freebie, someone had stripped the valves out of for a turbo application. So basically when the noobs walk in asking about disabling the system all of the veterans chime in to explain why it's a bad idea.

The weakest 164hp 160tq 2.5l engine was able to match a 5.0l FOX GT with 225hp 300tq, it was a driver's battle between the 2. Identical tested 0-60 times of 7.5 sec. It would probably be 8.5 - 9 seconds without the variable intake on the v6.

One of the things I've seen people do is cut the bottom of the runners off nice and straight and use couplers to connect to a homemade intake or if they wanted the square port runners to an oval intake without having to grind. Also as a way to test or run ITBs. Couplers might work with a 3900 intake. Probably plastic, which could still work. Tough to tell from pictures. A quick wikipedia read confirms LZ9 has a variable length IM, and it also says it makes 90% of it's tq at 1500 RPMs to 5500 RPMs, 240hp 240tq. VVT definitely helps those numbers. LZ8 doesn't mention whether it still had VLIM makes 7hp less. Also the LZ9 I can't see what the runners look like.

Someone smarter than me could probably figure out the math to get the timing right for something like this but it's probably going to be specific to what the individual puts together. So repeated runs through the gears tuning to get the best overall acceleration. If you use a LZ9 IM then you'd have to find out exactly the RPM it flips the valves stock and that should be close enough. If someone picked up a KL manifold you'd look those numbers up. That is once everything else is sorted.

What kind of sensors do the 60* engines use to operate, injectors? What year did they stop using distributors? What's the absolute max redline?

Re: Intake idea

Posted: Sat Nov 25, 2017 7:06 pm
by GT_Indy
It would be an interesting project, but I'm not sure if the potential gains for an NA 3400 or similar series v6 would be effective enough to justify the time and money on fabricating a variable intake for our cars.

There are at least two members I know of with 3500 engines with a lot of work and extensive port work, NA. They could tell you better about airflow on these v6's. Their cars are fast. One even has nitrous.

Re: Intake idea

Posted: Sat Nov 25, 2017 8:14 pm
by woody90gtz
Interesting design. I'm generally a fan of the "keep it simple stupid" build theory. Less things to go wrong. OEM cars are getting more and more complicated all the time and reaping the rewards...but they also do have better resources for R&D etc.

Re: Intake idea

Posted: Sat Nov 25, 2017 9:47 pm
by GT_Indy
woody90gtz wrote:Interesting design. I'm generally a fan of the "keep it simple stupid" build theory. Less things to go wrong. OEM cars are getting more and more complicated all the time and reaping the rewards...but they also do have better resources for R&D etc.

Same here. This is yet another reason I sold my turbocharged Indy and moved onto my cadillac.
Carb, distributor, pistons, cam, rockers, intake, done. No computer and no math, pick what works best because everyone's tried it before. lol, I love the simplicity. lol

Re: Intake idea

Posted: Sun Nov 26, 2017 2:56 am
Well after looking at some pictures of upper and lower intake manifolds it looks like it wouldn't work without some serious redesigning of parts. Or finding an VLIM that gets a lot closer. I saw an Acura 3.0l intake that looks like it would make a better starting point but would still take some hacking with other parts hacked in to attach to the top of the lower intake manifold. Or something like a hacked up SHO 3.0 intake, Which already is in a bunch of pieces and uses couplers, and then overall that intake is huge and would cover everything. Maybe I got the gears stirring in someone else's head. Still going to keep looking though.