Clearly we disagree which is fine but others certainly don't agree either that a aftermarket manifold ALONE will noticeably increase TQ/HP on built SBC, much less a stock base motor and the documentation does not support that claim either. I would like to see a Performer 2101 alone adding 20 HP to any engine? You stated combined with everything else a manifold change adds 20 HP. I dynoed 233 RWHP (Factory L-82 220 NET HP) with my stock L-82 with no emissions, shorty headers, 2.5 duals, Stock L-82 aluminum intake, stock 882 emissions cylinder heads, stock L-82 cam with a weak compression #6 cylinder.......in my case, the increase had nothing to do with the stock L-82 intake......100% all in the exhaust alone......

I have personally converted in prior years on other cars, 2 Performer manifolds, on two different GM 350 motors, as the only change and would not do it, ever again, since the benefit was barely noticeable as a manifold only change......sorry but i just don't feel the effort is worth the work for performance. Now for a weight savings? YES!

 

What I took from the OP's description is that he spends the majority of his time below 60 MPH and probably below 45 MPH. He stated below 4000 RPM.
So lets throw out everything above 4000 RPM, things like high flowing intake manifolds. Which is what he is asking about. Will an aluminum intake make a difference?
@ and below 4000 RPM with 882 heads and a very small cam intake manifold flow is almost irrelevant other than a dual plane is desirable for the low RPM operating range of the engine.
As far as headers go with OP's description it sounds like shorties with a max of 1 5/8" diameter, maybe even 1 1/2" diameter may be most relevant. This is not what I would use or would commonly suggest, but due to his situation it may be the most applicable. Some reading on that subject for the OP

https://www.centuryperformance.com/e...nd-length.html

https://www.hotrod.com/articles/ccrp...er-and-torque/

All things considered I would only go with a higher stall converter IF I didn't change the rear gear and only if an additional cooler is installed as the converter will spend much of it's time below stall speed making LOTS of heat in the transmission fluid.

On my 77 L-48 I first put on the side pipes re-jetted the carb for that and got a noticeable difference in performance.

Then I re-curved the HEI and advanced the static timing, again a noticeable difference.

then installed a 2400 stall torque converter along with a TH350 with a shift kit, another noticeable difference.

Finally rebuilt the carb with Cliff Ruggle's book. Noticeable difference.

Never did replace the intake manifold when the engine was stock, as I did not see it as a restriction to flow that was greater than that of the heads and cam in stock form.

I first did a 0 to 60 when I got it in stock form minus the air pump. 10.9 seconds This is @ 4500 ft not sea level, so some loss of power there.
edit: just read that the L-48 was advertised as zero to 60 in 8.7 seconds, HaHa sure...maybe.
https://www.zeroto60times.com/vehicl...-60-mph-times/

Each mod I made incrementally made it better ending up @ 9.6 seconds, 0 to 60 under similar conditions. Not a massive difference but sure was noticeable.
The tires could now spin and even chirp in a 1st to 2nd shift.

I see what Jebby is saying and normally would agree, but I'm not convinced that in this particular case it applies like most of the scenarios that we come across.

 

You guys have pretty much hashed it out above, but I agree with Jebby and suggest 2 1/2" pipes with the long tube headers, and set the advance curve.... thats where the improvement will be for your car.

 

I've been outspoken about changing a factory intake manifold right from the beginning.it's a crappy piece and always has been and it always will be anything you can put on there it's going to be an improvement. I would strongly recommend doing your tuning first and then adding your modifications in whatever order you feel suits you. And remember a modification may not give you as much of a result as you think but when you add other things it will increase the efficiency of it.there are several threads about the factory intake manifold I would encourage you to go back through and read some of them. We've almost destroyed friendships over the crazy thing.

 

I read that article, and it looks like an Edelbrock 2701 will give me a whole 7 ft-lbs more than the original one. I'm probably just as well off to just change the gaskets to the type that block the heat passage, fine-tune my new distributor and go with the dual exhaust I've got on order to do away with the Y-pipe and cat setup. That test was really interesting, I was amazed at how small the differences were. I can't see where saving a few pounds on a 3,550 lb car is worth it either.
I think I'll stick with the stock intake until at some time in the future, I may rebuild the engine and go to aluminium heads.
Thanks.

 

But where is the stock Q-Jet intake results?
There isn’t any.....
I think if you were removing the intake to swap gaskets that it would be nothing to pop $125 for an intake.....but it is your engine.
Flatout.....after 30 years of experience building small blocks and working on Vette’s.....I would not do the gasket job without installing a new intake.....it really is that terrible.....and then it is there for later upgrades....not to mention looks, weight and EGR delete.....

Jebby

 

I would do it just for the weight savings. $125 for 10 lbs is CHEAP. Not to mention that weight is UP HIGH, the worst place.

 

Just look at the factory intake with the carb removed.the turn from the carb baseplate to the intake floor is short and sharp, the runners small and twisted. A total lack of plenum volume.

 

More like 20-25 lbs savings....

Jebby

 

Yes.....how air attempts to flow through it is beyond me....and the bridge to the runners front and back is very small.
It is like GM just made a two barrel manifold into a four barrel.

Jebby

 

Before you start thinking that your gasoline is higher octane than what's in the US, know that the rating systems are different. Europe largely uses RON (Research Octane Number), which is numerically highest of all of the two octane ratings. MON (Motor Octane Number) is the lowest of the two octane ratings. In the US, we use the AKI (Anti Knock Index) which is an average of RON and MON ([RON + MON] / 2). So, your lowest (95?) is about equal to our lowest (usually 87).

 

https://www.musclecardiy.com/perform...ake-manifolds/


This typical, stock two-plane intake for a small-block Chevy utilizes a Quadra Jet carb. These feature small primary barrels and large secondaries. Because little attention was paid to port routing, the airflow on these intakes is very poor.


The routing of the runners for a twoplane intake can be seen here. The numbers in the ends of the runners are the typical flow numbers for a stock intake. After a week or so, porting the flow figures posted outside the runners was achieved. Although substantial gains were seen, these still fell way short of a highly developed modern two-plane.
https://musclecardiy.com/wp-content/...016/05/152.jpg

FWIW, Brzezinski says he flow tested some 150 different OE unported GM sbc Iron intakes and All runners flowed between 160-165 cfm. ...
...Elsewhere I found where E 7501 RPM Air Gap unported runners flowed average 216 cfm.

Regardless, I'm with hdeyong and his application his approach

 

Yes, and then you can get an intake that matches the performance of the heads at that time. Blocking off the crossover is a very good idea on your current setup if your going to take off the intake in any case.

 

If you are going to change the gaskets anyway, I can't imagine a reason not to also change the intake. Buying parts twice is bad enough, but doing labor twice is even worse. The weight savings is not insignificant, even if the engine won't notice. Just be sure to pick one that has the features you want.

The aluminum 14014432 intake was stock for 1980 and part of the 250 lb weight savings from that year, but requires an electronic choke.

 

Even at 100% VE (which it's far from) @ 4000 RPM that engine will only consume about 405 CFM of air total, that's for eight cylinders.

At a more realistic 80% VE it's only around 324 CFM. So where is the air demand from the engine that a better intake needs to supply?

Sure if I could pick up a really cheap used compatible intake made of aluminum and I was taking off the intake anyhow I would probably replace it. But I suspect that cheap GM parts may be somewhat rare in France.

 

^^^^this^^^^

 

Besides the 2 Performers that replaced GM cast iron manifolds on two stock 350's from the 80's that I swapped (with no real world gain), I have another real world example with my stock 78 L-82 4 speed (with 2.5 duals), see post #21, compared to a forum member's 78 L-82 4 speed with 2.5 magnaflow exhaust (actually better mufflers then I was running..AKA more flow) BUT also an aftermarket cam with more lift AND Edelbrock Performer RPM in place of my L-82 intake..ON THE SAME DYNO.

Results:
My 78 L-82 all stock with L-82 intake, stock heads, 2.5 inch dual exhaust...weak compression #6 cylinder: 233 RWHP

78 L-82 with stock Heads, aftermarket cam with more lift than L-82 cam, 2.5 magnaflow exhaust, AND PERFORMER RPM: 248 RWHP

Difference 15 RWHP.......both engines were revved to 6,000 RPM.

So let's think about this difference of 15 HP on the car with better compression, better magnaflow exhaust, aftermarket cam with more lift and slightly more duration AND a PERFORMER RPM intake?

Based on comments previously, documented articles, real world experience, and the results above^^^^who wants to bet the farm on the Edelbrock Performer RPM intake was responsible for the 15 HP gain?

The smart money would be on the cam and the exhaust....I certainly would not bet on the Edelbrock Performer RPM (guess and real world results, at best, 8-10 HP over stock intake, maybe, on a moderately built engine) and double negative for a regular Performer (5-7 HP).......which is very similar to the GM L-82 aluminum intake

ReelaV8R is correct that on a stock engine with STOCK heads, the intake is certainly irrelevant even when revved to 6,000 RPM. On My roller cammed 355 with AFR heads, my builder who has a mustang dyno in his shop clearly articulated that below 6,000 RPM based on his thousands of dyno pulls the regular Performer absolutely would be a waste of time versus my ported L-82 intake. Above 5,500 RPM, The performer RPM would give, on a good day, 10 HP which you would not feel on a 425+ Gross HP motor......

If I was going to ever replace my ported L-82 intake, I would hands down go with the GM Performance ZZ4 intake over the Edelbrock Performer/Performer RPM...any day....The GM performance ZZ4 is a better intake than both edelbrocks

 

Agree with the others on the exhaust Pulled that awful pellet convertor and single exhaust off my 75, added cheap long tube headers and true dual exhaust, and it ran like a different car with a different engine! Especially after I tuned the distributor.Very torquey and strong til 5000. Even with the 3:08 rear but I did have a 4 speed.

I suppose the manifold might help some, but the exhaust changes are much more important on that car.

 

Why are you doing this to a simple-minded question? NO - an intake will not give you a lot of horsepower - but if you have an 'adder' that forces air into it - well then, there you have it, you have something! The skinny answer to all this dialogue - Increase air "in" (a good intake manifold) - a camshaft to hold the valve open as well as close it at an optimum time and ramp, use a valve sized to flow the additional volume, and an exhaust manifold (headers) to expel the spent exhaust in such a way that the pulses scavenge one another and force the spent air out...Optimizing those pulses in a tuned way - that will net seat-of the pants power! GOLDEN BUZZER - Fuel, Intake air, valve lift and duration (as well as cylinder size and combustion chamber) combined with many other elements net real-feel gains! Its a combination and they should be addressed in a package sort of way - there are plenty of members that can offer packages that will net REAL Gains ........... no rabbit holes please - don't confuse this member - let's keep it simple - please...

 

Ok, that's good to know. I was going to go with our 95, and start at setting the timing to 36' at 3,000 RPM as suggested. And go from there.