Thread: Intake manifold options

In my Dyno sessions I found out that with a 3.5 OD piping and my Xcessive Plenum short runner setup with a shorter intake piping the motor lost as much as 9whp and 10 ft/lb of torque this means that increase in the length in the intake piping creates velocity on the intake charge hence more power!! I never tested 4in OD piping but I assume the bigger diameter piping will create less velocity on the intake charge!! Maybe a combined diameters will make a better intake but that will require too much Dyno testing for probably just a few whp!!!
This test will not apply to all IM setups!!
But it means that not necessary a bigger pipe will make more power!!!
Every setup its different and it will need to be tuned according to the setup!!!

I too tested an excessive with a q45,12" or so intake pipe and then lengthed it about 18" additional and gained 10whp without tuning yet. @Payu is right.

do you think that your results have something to do with your shorter plenum runners, or just the intake length? i ask this because i see alot of long runner manifolds using short intakes ( also oem ones). could the longer runner ones make more hp with a longer intake length. i have also read other threads saying approx 18''-24'' is good.
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meanwhile ariel cnc machine is busy...

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fancy a full billet plenum?

I have tested on both short and long Xcessive Setups!! The short one making more power @ high rpm than the longer one.
Short version setup with long intake arm its the best of both worlds!! Making most power and torque!! on All size motors from 2.0L to 2.4L
Have you tested on the Dyno different Intake length setups??

no payu i haven't, and i'm not arguing your results either, as you have been kicking ass for some time now. i have talked to a stack of knowledgeable people on the subject but, and as a general reply, they all reckon a longer runnered plenum will generate more power (7-11 inches), flying in the face of that reasoning is the shorter xcessive, the gato/bj , and the Matt Boddy manifold. all pretty short runners (5inches) all with seemingly good results and firm recommendations. maybe its in the tuning to these, or the plenum's air volume, or the tapered of the runners, i dont know. to me, if there was a concrete reason a short runnered plenum would work better with with somewhat fixed things like n1cams and 23/24 inch headers, then this would be an easy option. only problem with a longer intake from the t/b is there is generally no room to do so.

so there is something with your setup that really works. a combination of factors that produce results. how long is yours from the t/b back?

goood reaD!!~~

Payu, a few thoughts, I am going to this setup over winter and want to clarify some things.

The comparisons may not be equal for the longer intake piping. If you are using a velocity stack outside the headlight it will be drawing in much cooler air and it will have a ram air effect from being in front of the car, even from the dyno fan and not on the road. 10whp is a lot, but resonance and fluid dynamics (things i do not understand) may have a factor on why the longer tube makes more power.

With the shorter intake tubing it would be in the engine bay and will be warmer air. It would be nice to have it shielded from the engine bay and see if the results change. Was there no air filter on both setups? Everything equal besides length?

Just to clarify, what lengths are we talking about? 12" to 24"? or 12" to 30" as Gio suggested?

I will be upgrading to the Q45 TB over the winter and will try and make the intake tubing as long as possible. I have a divider between the engine and the air filter to keep the air cooler. I will be running an intake air temp sensor soon and i will do tests with and without the shield to see what temp difference this is. Maybe even do a Virtual Dyno log on each to see if there are any measurable differences.

Nice info Payu. I was waiting to hear about a few more intake combo setups that would work from 2.0L-2.4L motors. I just wish there were a few more BJ manifolds produced. I wonder how those would react with intake arm length changes.

i think bj's are alive and well, but trading under gato now

Gato Performance Kissimmee, FL

Gato has been a big name here in the Kissimmee-Orlando area. I have been to his shop and nothing but good quality pieces come out. He made a SR20 intake a while back to someone here on the forum and I have seen a few more in person from some local guys. Here is the thread Gato performance intake manifold and its a nice piece for only $850+Tax & Shipping. He is a big name here on the Drag Racing scene along with Kilo the best on rotary power cars. O&J Performance distribute a lot of Gato's parts since they are a local shop. But I personally would just go to Gato himself.
@KLUTCH