Carbureted LSX forum - GMPP L92 Dual Plane VS Victor Jr L92 Height (pics included)

I have both of these L92 intake manifolds on hand and thought it might be nice to get some height measurements posted for all to see.

I used a metal ruler and a square to try and get some reasonably accurate measurements.

Victor Jr L92: 5-15/16 (5.9375 'ish)
GMPP LSX Dual Plane: 5-23/32 (around 5.72" 'ish)

They are both impressive intake manifolds.

One thing that is hard to show in pictures is how nice the casting is on the GMPP L92 dual plane. The internal corners and transitions are so smooth and well done.

As for the question as to which intake makes more power, the answer is probably like most dual vs single manifold tests. The single plane probably makes the highest peak power and the dual plane probably makes the most average power.....

What I want to know is which one makes more POWER?

What I want to know is which one makes more POWER?

+1 on wanting to know the same!

I am going to make a sticky for info like this later this week. Guys need to get ready to offer some info.

So has anyone compared the 2 intakes yet? I am having a rough time on which way to tweek my LS3 in the 72 Camaro. My wife gave me the go ahead to get a custom cam ground, but I don't know that single plane LS3 headed STREETABLE cam tech is exactly figured out yet.
Im not concerned with lowest ET on my setup, but I want all the STREETABLE power I can get and still have plenty of vacuum for my big 4w disc setup and AC. I want to be able to stop at a red light w my 2200 stall and not have to knock it in neutral.
The cam I am running now does OK (comp LSR269-13....607/621,219-235 at .050 on a 113), but tip in is a little sluggish.
I think the GMPP Dualplane would work much better for my setup, but Id like some good #s before I drop 500 buck on an intake. I think the Vic Jr is a great intake for higher RPM power, but it and my LS3 heads have a lot of wide open spaces inside for good average power.

So has anyone compared the 2 intakes yet? I am having a rough time on which way to tweek my LS3 in the 72 Camaro. My wife gave me the go ahead to get a custom cam ground, but I don't know that single plane LS3 headed STREETABLE cam tech is exactly figured out yet.
Im not concerned with lowest ET on my setup, but I want all the STREETABLE power I can get and still have plenty of vacuum for my big 4w disc setup and AC. I want to be able to stop at a red light w my 2200 stall and not have to knock it in neutral.
The cam I am running now does OK (comp LSR269-13....607/621,219-235 at .050 on a 113), but tip in is a little sluggish.
I think the GMPP Dualplane would work much better for my setup, but Id like some good #s before I drop 500 buck on an intake. I think the Vic Jr is a great intake for higher RPM power, but it and my LS3 heads have a lot of wide open spaces inside for good average power.

Changing the pump shot and calibrating the carb should take care of your stumble.

The idling at a stoplight in drive should not be a problem with that cam and vacuum shouldn't be either. However I can understand your problem if you have the AC on and it in drive sitting still. The AC compressor takes some power and will definitely lower idle. They make a bump solenoid for the carb that is used to raise idle when ac is turned on.

Thanks for the reply, Stunningman, but Im running the Fast EZ EFI and I really don't have a stumble and the Fast computer steps the idle up when the AC comes on. It is just sluggish at low RPMs and Im wanting to optimize my setup. My set up is very mild compared to most and I just want to get the port velocity up, down low, where the engine spends most of its time.
Tightening up the lobe separation angle, which is what most grinders suggest on the LS3 ,single plane setup would make the engine more sluggish down low and tighten up the torque to horsepower spread. That would be great for an all out drag setup, but not for what this car was built for. That's why Im asking about the dual plane. I would think the 113 lobe sep my cam has now would work better with the longer runners on the dual plane. Do you all think im on the right track with that thinking?

The cam I am running now does good at stoplights in gear. I am just worried that a cam ground for the single plane would create a problem in stop and go driving.

Thanks for the reply, Stunningman, but Im running the Fast EZ EFI and I really don't have a stumble and the Fast computer steps the idle up when the AC comes on. It is just sluggish at low RPMs and Im wanting to optimize my setup. My set up is very mild compared to most and I just want to get the port velocity up, down low, where the engine spends most of its time.
Tightening up the lobe separation angle, which is what most grinders suggest on the LS3 ,single plane setup would make the engine more sluggish down low and tighten up the torque to horsepower spread. That would be great for an all out drag setup, but not for what this car was built for. That's why Im asking about the dual plane. I would think the 113 lobe sep my cam has now would work better with the longer runners on the dual plane. Do you all think im on the right track with that thinking?

I think your a prime candidate for cathedral ports... but I wouldn't suggest that with the high dollar amount you have in your current set-up. I too, would want to work around it.

I feel you need more stall (2800-3000) it will go a long way to giving you what your looking for in mid-range and use the lock-up for cruising.

For the cam specs, talk to Patrick G or maybe even Predator Z as they have dealt with EFI set-ups like yours in the past. Biggest thing is find someone thats dealt with the FAST EFI stuff you have...Its unlike factory efi or carb when it comes to cam preference.

I would look at (google search) results from other engines with the FAST EZ EFI SBC, SBF, BBC etc that have done dyno comparisons (between single plane and dual plane) and expect similar results and pitfalls.

What timing do you have in this motor at idle? And through the lower rpms?
On an EFI setup, I do NOT see a dual plane helping you. The dual plane would help if you had a carb, as it would increase the 'signal' the carb sees.
It's in the tuneup.

What timing do you have in this motor at idle? And through the lower rpms?
On an EFI setup, I do NOT see a dual plane helping you. The dual plane would help if you had a carb, as it would increase the 'signal' the carb sees.
It's in the tuneup.

I will have to look at it but i think I have the #4 pill in the MSD 6012. I havent laptopped the MSD yet, But dont you think the air velocity through the longer runners of the dual plane would do a better job at lower RPM. the fast EZ is a throttle body injection, not port, so I would think it would act more like a carb, other than the fuel atomization being better with injectors vrs the carb.
I have been lead to believe that longer runners give better velocity and better low RPM power regardless of fuel delivery source .

http://ls1tech.com/forums/conversions-hybrids/1287948-timing-curve-msd-6012-l92-carburated-3.html

If you are using pill #4, you might respond favorably to some additional advance.

http://i373.photobucket.com/albums/oo180/marcoo77/camaro/MSD6012timing.jpg

YES, it would respond VERY favorably to more timing, and especially more aggressive low rpm timing.
Put pull #6 in it for now , but get a laptop on that MSD and program the timing! It will wake up big time at the low end and throttle response.
My opinion is program something like this in:
*15 0-1000
Ramp from 15 to 26* from 1000 to 2000
Then strait 26* 2000 to top rpm
This is far from perfect, but should help out a TON! I think it will want more timing, probably 27-29*, but better to play safe to start with.
Do you have a map sensor connected to the MSD?

No I to not beleive the dual plane will have any major effect, because of the EFI. Try tuning the timing before spending money on a dual plane .

Ok, just verified the #4 was in the box. I do remember trying the #6 and getting a tad of spark knock, but I just put it back in for another try.
No ,I dont have a map sensor plugged into the box.
I still cant get my mind wrapped around longer intake runners not helping with air velocity and that not helping with low end torque. Its kind of like saying the LS3 head has as much low end torque as a cathedral port.

I still cant get my mind wrapped around longer intake runners not helping with air velocity and that not helping with low end torque.

No need to stress about that. The dual plane absolutely will bolster torque substantially at low RPM.

I think what others may be suggesting is that if you get what you have properly tuned, you may have satisfactory low RPM torque.

How much stall converter do you have?

That's exactly what I'm suggesting.
I question wether the dual plane will provide much benne fit specifically because of the EFI. I know it will help a carb'd setup, as it will provide more 'suction' to pull fuel through the boosters which will give much more seat of the pants torque off idle and through the lower revs. BUT if the EFI is providing the correct a/f ratio already , then the gain may be much less noticeable. That's why I'd chase the tune instead of swapping manifolds.
I'd like to know how that 'EZ EFI ' works? Is it a closed loop setup that is always following a pre determined a/f ratio from a wideband? If so can you command a different A/F ratio at different rpm/ and or load situations?

Tigger, I am running a 2200 rpm lockup converter.

3 pedels, the fast EZ has a baseline a/f ratio built in its base line tune, but you can command any a/f ratio you want. It allows you to reset idle a/f, cruise a/f, and wide open a/f. Once set, the computer shoots for those #s constantly. The more you drive under each condition, the more accurate the a/f gets. Its kinda fun to watch the monitor while the computer fights to get on target.
I cant help but agree with Tigger on the dual plane torque. Like a wise member said yesterday, if long runners didnt effect the torque, why would GM go to all the trouble to make the LS truck intake runners longer, well, for more low end torque?

Tigger, I am running a 2200 rpm lockup converter.

With that tight of a torque converter, you may prefer that dual plane intake. I don't have square port heads, but on my ported cathedral port heads my car was quicker for the first half of the track with the dual plane and that was with a 2800 converter. Unless you have more power than you need down low already, I would probably try that dual plane if it were me.

Like a wise member said yesterday, if long runners didnt effect the torque, why would GM go to all the trouble to make the LS truck intake runners longer, well, for more low end torque?

:thumb:

Like a wise member said yesterday, if long runners didnt effect the torque, why would GM go to all the trouble to make the LS truck intake runners longer, well, for more low end torque?

Makes sense to me :naughty:

SURE it does! Especially when YOU are the wise man that said it! :D

If you want to change to the dual plane that's up to you. It'll work great. But I beleive there is substantial gains in the tune with the manifold you have.
What are the commanded a/f's? List them all, Everything from idle up.
I agree that the long runner LS EFI intakes are pure torque producers, but my opinion is a dual plane carb intake is a major compromise . Its design is to increase booster signal on a carb , your efi doesnt really need the divided plenum to work well. Thats just my opinion, and you don't have to agree. I'm just trying to help you get what you have running better.

I agree there is alot left in it. I havent even really started to play with the tune, but I want to have all the players in place before I get serious about tuning. I use to love changing jets and dist. springs, pump cams, twisting the distributer back and forth and test drive, test drive, test drive. I still have an old school sbc 68 camaro Hotrod sitting in the garage if I ever want to play again, but this car is to be tuned up once and drive,drive drive.LOL.
For what this car is set up to do, the dual plane will work better than the single. How much better, I will never know for sure because I never really tested it the way it is, so I wont be able to compare.
Im almost positive I am sending paypal for the intake tonight and Im thinking hard about advancing the cam I already have a couple degrees too. Then I will dial it in, hopefully with a little help from my friends on LS1tech, and be happy with it.
3 Pedals, I will check the a/fs for you in a day or two but they are at the factory settings . I think they are 13.5 idle, 14.0 cruise, and 12.5 WOT, but I will have to check to be sure. Thanks for the input, guys. It is greatly appreciated !

I just realized this was a MAJOR thread hack! Lol, my apologies for completely derailing your thread TopBrent

LOL! I dont think Topbrent minds too much. This thread was pulled up from the dead while I was researching the dual plane LS3 intake from August of last year.:secret2:

No worries! It is all applicable information.