DO NOT ATTEMPT THIS "FIX"!!! I RAN INTO A SERIOUS PROBLEM, READ POST AT END OF THREAD Well, it looks like I may have come up with a solution. The AFR's at idle at still .75 or so apart, but the rest of the time (both cruise and WOT) I have both sides +/-.25 AFR, and the higher AFR switches from side to side. How'd I accomplish this? Don't laugh to hard.... I got to looking at a spare SR plenum I had, and picturing how the airflow would go. Driver's side runners are farther back, more of a gradula flow turn to get most of them. And that was my leaner side to start with. The richer (getting less air) passenger's side airflow has to make a hard turn to feed those farther forward runners. So, I thought, why not try to balance out the flow? Took some measurements, did the calc, and discovered how I could turn the one big plenum into two smaller plenums of almost exactly the same volume (difference is less than 5%). So here's a pic of my temporary solution. If I decide to keep it the RTV will go away and I'll tap the plenum base for screws to bolt it down. Currently the divider is only .025 thick, will make a heavier stiffer one as well for a permanent install. Made a pattern out of poster board first, then used that to cut a slightly oversized aluminum pattern, then hand filed it down to fit - and put a small piece of split vac hose on the top edge and fit it to seal against lid. So, what problems am I liable to run into with 2 equal sized plenums for each side of the motor vs. one big one? Any suggested performance differences I might expect? I've also got hi-res pix if anyone wants to see them. I'd appreciate the input, and sincerely and greatly thank everyone for all the help and suggestions on this deal.

You might try cutting back the divider until you see your idle afr start to
mess up again. Then go back to the last divider size.
You won't need the top seal of course.
All sorts of different ways you could test that divider with angle and such.

More plenum volume will help the top end I believe.

Also, you'll need to go thicker on the divider, I'd be worried about it wiggling.

Now that's good ole' fixin' it
At least you are able to prove without a doubt that it was in fact high/low velocity flow patterns within the plenum causing the unequal distribution.

Excellant detective work Vern. Now just need to fine tune your idea.

I'll probably adjust my IAC down so the air is almost all coming thru the blades for starters. Right now the IAC is around 40-45 at idle, want to see if that will make any difference.

Since I was already seeing the AFR's balancing out under moderate to heavy load, which is the most important part in my opinion, I'm not sure I'm going to permanently use the divider. Especially since it may hurt the top end. Frankly, The Butt Dyno tells me that the divider is hurting acceleration alittle bit as well, especially the tip-in portion. Doesn't seem to react to the throttle moving as much as it did....

Well, if that’s the issue then you should be able to get the same effect without splitting the plenum down the middle by mounting a diffuser right behind the throttle body in the plenum, forcing the airflow around the diffuser. A larger plenum volume should have the same effect and increase peak hp (again, if you’ve found your problem).

OKAY FOLKS - I JUST DODGED A GREAT BIG BULLET WITH THIS PLENUM "FIX"......

Within a hundred miles of driving, I started to feel what I thought was a noticeable drop in power; accel and tip-in just didn't seem as strong as before I put in the divider. I mentioned another anomaly I saw in a couple of data logs to Z69 - random periods when the knock counts would start climbing quickly (5 to 10 per second). Since the knock counts were causing some serious spark retard, I wondered if that was the power loss cause. Couldn't find anything wrong with the KS or connection to it, so I was really scratching my head.

While trying to figure out what to do next on the knock counts, I figured I'd remove the spacer and see if the perceived drop in power was related to it.

What I found when the plenum lid came off was shocking (see attached pix). The divider I had built was curled away from the back of the plenum on the end closest to the firewall. Like the vacuum was strong enough on the driver's side it had pulled loose the RTV holding it down. Then I looked closer at the divider and saw that a piece was missing. The last inch and a half or so of the divider - plus the two steel angle brackets attached there - were not in the plenum! (I know Grumpy, sounds like deja vu, doesn't it?) I had seen what a half inch piece of aluminum slag from an intake manifold could do to pistons and valves previously, and was suddenly scared to death about where that missing piece of aluminum and the two angle brackets had gone to.

I couldn't see it down inside any of the runners, but I knew it had to have gone that way. So I started fishing down each runner as far as I could with a magnet on a flexible shank. The aluminum divider was not magnetic, but I knew the angle brackets were. To make a long story shorter, I hit something in the #2 cylinder's runner about half way across the intake manifold. It took me over an hour of fishing around in that runner to finally get the piece turned just the right way so I could get it all the way out.

I had found the source of the mysterious knock counts - it was the torn off piece rattling around in the plenum most likely. Lucky for me it was just a c?nt hair too big to make it all the way across the intake manifold to the valves. If you look closely at the pics, you'll see a stress crack above the large center brackets as well.

That's the end of my plenum divider testing. In the 30 miles or so of driving since I out everything back together, there is definitely more power during accel and tip-in without the divider. The larger plenum volume definitely does appear to help the power end of things.

And if anyone ever tries something similar to this - USE A MUCH THICKER DIVIDER WALL, BOLT IT TO THE PLENUM BASE, AND WELD ALL NUTS SO NOTHING COULD POSSIBLY COME LOOSE AND DESTROY YOUR MOTOR!!! I had to buy a couple of pistons and valves - AND BLOCK - when some intake casting slag got loose in a GMPP 454HO I had a few years ago. This time all it cost me was time and a plenum lid gasket. I was extremely lucky.....

Now back to the split AFR problem. Under sustained moderate accel or load, it looks like the difference is minimal if it exists at all. Especially over about 2500RPM. A WOT blast in 2nd gear I did appears to have less than .5 AFR difference and sometimes is even less. That's probably about as good as it's going to get, apparently the characteristics of the S.R. at idle and low flow are a little unbalanced. Not surprising considering it's shape.

Wow, that was close.
Can imagine the fear of "where did it go?"
Had to drive 10 miles the other night with nothing on the TB cuz my CAI got messed up. Was praying nothing came off the road.

Was that last split reading after you removed the divider?
seems much better than before.

Yeah, I just about dirtied my drawers when I saw that....

As for the split, it does look a lot better than it did. Sealing the headers on the driver's side appears to have made a pretty big difference, along with the re-sealing of all the intake gaskets. Still seeing 1.2 - 1.5 split at idle, about .5 - .8 at level cruise, but it gets closer under a pretty good acceleration load and WOT.

After all this, it looks like I've found that the S.R. appears to have some slight air flow distribution problems at low load conditions, but they decrease as the load increases.

So unless there is something else going on in my motor, I don't know what else to say/try/do. If I had access to another set of heads or a converted LT1 intake, I'd slap it on and try to see if either made a difference. But alas, with 3 kids getting married this spring and summer (two son's down, but one daughter yet to go), my "play budget" has been severely limited for a while....

Vern - When you find the extra cash, put a MiniRam on your motor. I guarantee you will not be disappointed!

Probably not, been seriously considering a converted LT-1 intake to be honest with ya (primarily due to the lower cost)...

Kind of reminds me of the quote "A man with one watch knows the time. A man with two watches is never really sure." Forget where I read that one, probably google.

All too true Jeremy - I've still got some differential between the two WB's, but I've got it down to .75 - 1.0 at idle and around 0.5 at cruise, a little less at WOT but it actually seems to flip-flop between the sides at WOT. So from all appearances, it is something inherent to the SuperRam. Guess I'll just tune for for which ever one appears to be the leanest to save engine damage. Especially if I ever decide to install that NEX kit I have sitting in the garage.....

Thanks to all for all the suggestions and ideas - and for any future ones anyone thinks of! (or I missed trying in this marathon thread...)

Vern - sorry I missed this thread a while back. Did you do a search for split BLM's? There is info that I posted on this more than once. It sounds like you got most of it resolved. My take on this is until GM went to dual O2's nobody knew about split BLM's. They also happen to be a mechanical problem and as you found out mostly at idle unless you have an exhaust leak. If you can datalog with both sides at the same time try opening the blades slowly. That is the first LT1 fix. The next is a small bleed hole, etc.

Yep, I read all the stuff I could fine on split BLMs. Including the use of an idle "tube" if you will. Unfortunately my hacked $8D can only datalog one WB at a time. I'd love to be able to d/l both simultaneously. I suspect you're right that no one knew about the issue prior to the LT1 since so few were as anal as I am and put a sensor on both sides of the motor. I'll be installing my new AFR 195s in a couple of weeks, and may try a converted LT1 intake I have and see what it does. It makes sense when you consider the shape of the SR plenum that it wouldn't be balanced at low flow rates. Hopefully the LT1 will be better. If not, or if it hurts my performance, at least the LT intake is easy to remove to reinstall the SR...

I am running a LT1 intake and had the same problem. I was hoping that maybe Z69 and JP would incorporate a 2nd O2 datalog into S_AUJP for this reason. I have an old style TB that was modified to a 52mm by ASM and I used JB to seal it up like a newer style TB. I ended up drilling a .16 hole. I have not put my WBO2 in the other side though to 'adjust' the blades. If you go with the LT1 with AFR 195's I can provide you with a bin to start with...
.

You have mail.....

What a story.......

I'm also fighting split AFRs on my car, but havent found anything...yet.... But I have the HSR intake......

My LH AFR is rich @idle and lean at part throttle WB in RH shows 14.7 both times.....

Hopefully I will find something this winter...........

/N.

Bummer, be sure to check for any open welds on the exhaust or other sources of fresh air getting into the exhaust. You've read the B.S. I went thru, vac leaks and crummy headers I'm gonna have to pull and get all re-welded. Unfortunately they are SS with ceramic coating, so it won't be an easy job - which just means it will take even more $$ I don't have.....

I hope you find out where your gremlins are, Vern.
Pretty scary pics of that divider getting chewed up in your plenum.

-Steve

I think my solution, or at least the next step(s) in my plight is going to be trying an LT1 intake and getting the headers welded up and checking that they're straight (not warped)....

that sounds like a plan, trashing the super ram for the moment?

At least temporarily. Got some AFR 195s and new retro lifters, plus a Hydra Rev kit to install and figure I'll put the LT1 on it to start with...

awesome man, sounds like fun. good luck

I know this post is old but, I think you answered your own problem early on. The summit pcv valve is a leaky pos! I'm surprised it didn't fall into your engine) and looking at yor pics WTF? the pcv system should not be taken lightly. (what's up with the wierd hoses? anyway before installing the SR be carefull to poke and check EVERYWHERE for sand cast holes that can cause a mystery leak other than the ones that come with the SR naturally. A lack of information leads to speculation, a further lack of information leads to wild speculation. Someone should sue summit about this billet pcv pos.

So you think the Summit PCV is bad? Interesting.....

I've made some changes in the 2 years since this thread - running a 1205 MR, AFR 195 Eliminators, new XFi custom Comp retro fit cam (236/242 @050. .580 lifts with my PM 1.6RRs, BBk 58mm (still).

One issue I have with PCV valves is how does one go about selecting the "right" one? Seems like the release pressure would have to be different for various motors since they all draw different vac numbers at idle, etc.

May have to make that question a different thread....

iv been running the super ram for 14+ years. it comes off to install a new eng. go's back on and works 100% of the time never any Hickups!!

dont know why so many guys have probs.

it's never leaked..anything.. always works..
one of the first things to do is set up the 4 bottom inside runner bolts with slots (for screw driver) so you can install/remove with the lid off..
no need to safty wire. of goofy things like that..

Lingenfelter did My 92 Z28 back in 93. never have had the intake Give me probs Ever! But then it's all accel parts.. not miss matched .

Arctic, read the whole saga. I know you love your Lingenfelter set up, but the intake has a design flaw that you cannot get around. It is minor, but is still there.

i did read it.. LOL why would you think the AIR box (thats what the top is)
would make one side. rich or lean. when it's EFI and the pistons draw the air and fuel into the eng...lol

never had any probs with mine..it's now going on a 11.8.1 427sbc
with a DART block.. anlways use the right parts dont miss match, and you will have few probs...

it's simple to install.. so there is 2 screws that take a few more mins to get to..

did you know lingenfelter used this intake to make a 420sbc that made 400 fpt at just off 1600 rpm.. YES I LIKE my super ram.

i like the fact i have used this intake to get my street car into the 10.s
with out goofing with it.. and the other half can drive the car to get her nails done...(was late getting home and she took my car)
was late by 10 min!!

sorry your having probs... i never have.

you are absolutely correct. do a slow methodical installation with the superram and it will assemble fine. bench build it first just to get familiar. build it loose and tighten slowly once it is all together. it will work fine.

I've had mine off and on a bunch of times..No problem, love the SuperRam!

i dont see any. and I have not run into any..

It was made to make Gobs and Gobs of TORQUE!!
and dose so. think of a 420+ sbc that makes 416 fpt at 1600 rpm
and gos up to 560+lbs of torque right to 6000rpm.
and almost 600hp. now put that in a street car. your HSR will not touch #'s like with torque. and you dont have to spin it up to 7000.

with the RAT size cubes in aftermarket small blocks now.. and Rat size Torque #'s
the super ram shines all over..! would i do a 383 a 2nd time..NO!

420 427 434 440 454 THIS IS THE NEW line of small block chevy eng to Hot Rod.if using the OLD styl sbc with the super ram get that 4" stroke. and make some torque..to move it down the street!!

aftermarket all forged short blocks for any of the above size eng is only $2999.99. thats with a Dart or chevy Bowtie block and 4 bolt.
all the way up to 13.1. add a set of good heads and super ram intake.
your start to need some big sticky tires!

Mine was all Accel parts too, except for the head LOL.

Glad yours is working out great, it just didn't for me. Love the MiniRam though, been totally trouble free. Unbalanced AFR (right side runs richer) at low throttke/vacuum operation, but balances out at heavier throttle pushes.

is it possible to get the super ram anymore? also, what type of MAF do you guys use when you're making that much power?

From what I have heard they dont make the SuperRam anymore..You might have some luck on Ebay..

My guess is there is a good reason they may not make it anymore. I'd suggest rather strongly you look into the Accell Big Mouth, converted LT1, or MiniRam if you need more air flow through your intake. It will start a rash of replies from current owners, but IMO don't waste your time with the Super Ram. YMMV, of course!

Vern didnt you used to run a SuperRam? I love mine, never any problems and works awesome with my 383. They made it for like 20 years, Not that many ppl modding 3rd gens as there was back then and other companys have come out with other intake to compete with it. Sure Accel is focusing there time and money on new cars which is a bigger market.

There is the new Edlebrock setup that you guys might be able to pick up from them without the electronics. I guess somebody would have to call them and see......

the TPI cars also are not made anymore. and everybody should know thats why they dont make them(super ram) anymore..lol

If you under stand how they work, and how to make a eng to use it, then you will have no probs, with the right parts it's a 11 sec eng in a 3400 lb car. that is fun to drive and all this under 6100 RPM. that will pass smog in all the states.

was/is it hard to install...No!
did it take 30 min longer to install..Yes!

some eat from a can, cuss it's easy,
others like to Grill, but its more work

Yep, I used to use a SR on my 383. Then I got tired of always fighting vacuum leaks. I went through like five sets of gaskets in 2-3 years with it. Fix one, and 3 weeks later one would crop up somewhere else. So I shelled out the $$$ for a MiniRam, and I've never regretted it. More power, no vacuum leaks in three years, sets lower in the engine bay, and IMO has a "cleaner look" under the hood.

All I can say is this:

In my case, the MiniRam has worked out a lot better for me. YMMV, of course.

I wouldn't be happy if I had vacuum leaks myself. I've been lucky and never had any in the 10 years I've had my SuperRam. I've had it on and off like 5-6 times when doing mods or changinging motors. I've been able to use the old gaskets without issues. The MiniRam is nice and will give you some more HP then the SuperRam, but the SuperRam will give more TQ then the MiniRam. Maybe your SR was a bad casting. Good to hear your having no issues with the MR. Whats your car running in the 1/4 Vern? Looks like a similar setup to mine. Havent gooten a chance to get mine to the 1/4 yet.

have never had any leaks my self either, and with the right parts in my 383 ran it 11's in the 1/4 mile right at 5900/6000 rpm give or take 100rpm.

but now with the new 427 cid (4.125 bore x4" stroke) and 12.1 CR
im starting to look at diff intakes as this new eng makes gobbs ot TQ
the only ones i see is a new in box miniram $550 with all the small parts. or the steath ram.