Trying to decide on an intake manifold...
11-26-2016, 12:38 PM
#1
Trying to decide on an intake manifold... Hey everyone,
I've gotten my engine back from the builder, & (as the subject line says) I'm trying to decide on which intake manifold to use. Here are the relevant details that I can think of right now:
At the moment, I'm thinking that I'll go that route if I have to, but man, that's almost like lugging around another aluminum cylinder head!!
I'm really not sold on the idea of using a stock polymer intake manifold (i.e. a Camaro or truck intake) with forced induction, so I guess that leaves something like a carburetor-style intake like a Victor Jr or similar. But I don't have a lot of knowledge about how those work with turbocharging. And how do the costs compare once you've added in all of the parts necessary??
I'd appreciate getting the benefit of others' experiences. Thanks in advance.
I've gotten my engine back from the builder, & (as the subject line says) I'm trying to decide on which intake manifold to use. Here are the relevant details that I can think of right now:
Car - late 3rd-generation Firebird;
Engine - aluminum 6.2L w/ L92 heads;
Induction - single turbocharger, shooting for around 675 ft/lbs;
Transmission - T56;
Intended Use - 80% street, but also road-course & open-road events, with an occasional standing-mile event as well.
The engine builder recommended an intake like the Holley mid-rise - which I was all set to use until I picked one up & found that it weighs like 40 lbs! Engine - aluminum 6.2L w/ L92 heads;
Induction - single turbocharger, shooting for around 675 ft/lbs;
Transmission - T56;
Intended Use - 80% street, but also road-course & open-road events, with an occasional standing-mile event as well.
At the moment, I'm thinking that I'll go that route if I have to, but man, that's almost like lugging around another aluminum cylinder head!!I'm really not sold on the idea of using a stock polymer intake manifold (i.e. a Camaro or truck intake) with forced induction, so I guess that leaves something like a carburetor-style intake like a Victor Jr or similar. But I don't have a lot of knowledge about how those work with turbocharging. And how do the costs compare once you've added in all of the parts necessary??
I'd appreciate getting the benefit of others' experiences. Thanks in advance.
11-26-2016, 12:46 PM
#2
Plenty use the polymer intakes with boost and push big number with them. Your target torque will be absolutely no problem with the turbo setup. Might was to take a long look at the Holley intake and make sure it'll fit your combo (not physically LOL). Some intakes require quite a bit of rpm to make them shine over the factory stuff. JMO.
11-26-2016, 10:47 PM
#5
Stock truck intake. Mine clears under my 87 firebird power bulge hood too!... If not then a LS6 but they make the same power but the truck makes more low end/mid range. My 5.3 with 12psi is a lot of fun in my 87 TA. Going with ported stock heads and a cam this winter and a rebuilt valve train.
TBSS intake or NBSS truck intakes are better due to larger TB opening... but as your boosted it doesn't matter. The stock truck intake weights like 10lbs maybe lol... I just bought a new one for a whopping $70 shipped. Plus the plastic will run cooler than anything aftermarket.
Like I said... 12psi on my stock truck intake and its never been unbolted in 150k miles and no issues. They have been much higher than that as well... they are very strong.
TBSS intake or NBSS truck intakes are better due to larger TB opening... but as your boosted it doesn't matter. The stock truck intake weights like 10lbs maybe lol... I just bought a new one for a whopping $70 shipped. Plus the plastic will run cooler than anything aftermarket.
Like I said... 12psi on my stock truck intake and its never been unbolted in 150k miles and no issues. They have been much higher than that as well... they are very strong.
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11-28-2016, 10:35 PM
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11-29-2016, 10:12 AM
#13
FormerVendor
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Cadillac Intake L-92 I AGREE, use the "Cadillac" of ALL intakes, the L-92 as is fitted on my 2008 Escalade.
REASON : Cost is always first though is this case, a turbo, you can get the "best" of both worlds.
Turbos LIKE long runners AND smaller intake ports compared to a N/A engine.
This factor "lights off" (spools) the turbo at LOWER RPM, once at song, power IS controlled by MAP.
ANOTHER reason, of GREAT concern, IS manifold temperature.
Most AL manifolds, not MY 65mm ITB's, will absorb "heat" from the IR of the engine.
This is one MAJOR reason "plastic" manifolds make more power if the design is the same.
DON'T waste money on "oversize" Air Doors for turbo use, the OEM 90mm will be fine.
MANY OEM's will REDUCE the inlet bore of the Air Door when a turbo is added to their N/A engine family.
Lance
REASON : Cost is always first though is this case, a turbo, you can get the "best" of both worlds.
Turbos LIKE long runners AND smaller intake ports compared to a N/A engine.
This factor "lights off" (spools) the turbo at LOWER RPM, once at song, power IS controlled by MAP.
ANOTHER reason, of GREAT concern, IS manifold temperature.
Most AL manifolds, not MY 65mm ITB's, will absorb "heat" from the IR of the engine.
This is one MAJOR reason "plastic" manifolds make more power if the design is the same.
DON'T waste money on "oversize" Air Doors for turbo use, the OEM 90mm will be fine.
MANY OEM's will REDUCE the inlet bore of the Air Door when a turbo is added to their N/A engine family.
Lance
11-30-2016, 09:50 AM
#15
11-30-2016, 05:06 PM
#16
Originally Posted by LJMSJohn
because you are talking about road racing the car. an LS3 intake valve is 30 grams lighter than an L92 intake valve.
L92 intake valves border on impossible to keep under control imo.
L92 intake valves border on impossible to keep under control imo.
11-30-2016, 09:08 PM
#17
TECH Fanatic
If your "builder" is telling you this, you need to find a new builder.
The fact that you are building an engine to make under 700hp at all is kind of ridiculous really.
The fact that you are building an engine to make under 700hp at all is kind of ridiculous really.
12-01-2016, 06:23 PM
#18
Nismo Kid - Wow, that's pretty definitive all right, thank you! That is basically impossible to argue against. The only BAD thing about that is that over the last few weeks, I'd read quite a few posts (yes, right here on LS1Tech!) arguing that the stock intakes were useless for boost - and so I sold the one I had... 
customblackbird, 3 Window, Pantera EFI & LJMSJohn - thank you for providing specific additional info, that's much appreciated.
The fact that you would post this - without having the sense to think "Hmmmm, maybe there's a reason that the engine needed to be built" - marks you as someone who apparently doesn't think before he posts... 
For the record, this started out as a fairly-mild, naturally-aspirated build, I was shooting for around 550 hp. I bought a newly-rebuilt transmission that was rated for 700 ft/lbs. (well beyond the engine output that was anticipated at the time), which is WHY I'm keeping the boost relatively low - This is a BRAND-NEW transmission, & I don't particularly want to rip it back out & spend MORE money rebuilding a transmission that's never even spun a gear yet!
Two things happened recently to change the direction of this build:
1) I discovered that the original crankshaft was damaged & unusable; and
2) I transitioned into a new job that pays twice what my previous career did.
Since the crankshaft had to be replaced anyway, & money was no longer an issue, this allowed me to build the entire engine with an eye toward the future. I'm sure that one day I'll probably step up to an even beefier transmission - but is anyone seriously going to make the argument that you can't have fun with 650 - 700 hp??!? Seriously??!? Come on...
Anyway, enough of that. I DO appreciate most of the feedback that's been provided in this thread, especially since it means that I don't have to drop $800 (or whatever) on a bunch of new intake parts. Thanks guys.
customblackbird, 3 Window, Pantera EFI & LJMSJohn - thank you for providing specific additional info, that's much appreciated.
For the record, this started out as a fairly-mild, naturally-aspirated build, I was shooting for around 550 hp. I bought a newly-rebuilt transmission that was rated for 700 ft/lbs. (well beyond the engine output that was anticipated at the time), which is WHY I'm keeping the boost relatively low - This is a BRAND-NEW transmission, & I don't particularly want to rip it back out & spend MORE money rebuilding a transmission that's never even spun a gear yet!
Two things happened recently to change the direction of this build:
1) I discovered that the original crankshaft was damaged & unusable; and
2) I transitioned into a new job that pays twice what my previous career did.
Since the crankshaft had to be replaced anyway, & money was no longer an issue, this allowed me to build the entire engine with an eye toward the future. I'm sure that one day I'll probably step up to an even beefier transmission - but is anyone seriously going to make the argument that you can't have fun with 650 - 700 hp??!? Seriously??!? Come on...
Anyway, enough of that. I DO appreciate most of the feedback that's been provided in this thread, especially since it means that I don't have to drop $800 (or whatever) on a bunch of new intake parts. Thanks guys.
12-02-2016, 04:38 AM
#19
9 Second Club
I would find that very hard to believe...unless perhaps the threads are maybe 16-17 years old. ie when the engine first appeared and nobody had used one.
Although in the early years, there were some very bizarre notions people were coming off with even for back then which have later been proven total nonsense
12-02-2016, 08:33 AM
#20
Restricted User
Without knowing that you were building it because it was broken, his post makes more sense than him being able to read your mind.