gutted intake and weak low rpm torque

[1dollardog]

Will a gutted hot air intake hurt low rpm torque? I have heard in the past that it can. I gutted one to the extent of having no "torque tubes". It seems like it would flow more freely and cooler however I've heard that it will hurt you on the low end. Any truth to this?

 

[charlief1]

Because of the size of the inside of the intake the turbo has to fill it up so the speed of air going to the engine is slowed down. It has to do with the velocity of the air charge. More area will slow the velocity down so when you need high speed velocity at low RPM's you won't get it. You have to remember that if you "gut" a HA SFI intake the insides are almost twice the area of an IC intake.

It's kinda like using an open NA intake versus a divided one. The divided one will work better on the bottom and an open one will work better on the top.

 

[turbofabricator]

I've done that and ALOT more to a HA manifold. With EFI port injection all the runner length issues are null and void (to a point). The dang stock manifold just can't possibly flow any air to speak of. MAN that thing is a complete pile of doo-doo. Cut one apart and see how restrictive it is. I had to add 5 lbs. of welding rod to the runners to get them up to a flow potential, too. I ported it out to a Fel-Pro 1200 and did alot of other unmentionable "tricks" to the inside. Some day I will post pics, but it is still in the development stage at this point and won't divulge the details..........yet. So......if you have a big turbo and ported heads, cut that thing apart, and grind about 2/3 out of it. Add ALOT of alcohol and watch it make power. The air path it has to travel to make it to a cylinder head is about 5 miles and the actual ports are smaller than a gnat nostrils, too. At 400 hp the air is probably going super-sonic to make it through it.

 

[Boost231]

just remember when you gut the intake you are changing the flow rates at each port.. you will no longer have equal flow to each port...

 

[boostmaster]

It has been proven time and time again that long runners create low end torque. Why do you think all the new cars come with long runners on their manifolds? even the low rise intakes on new cars have long tubes on them. Look at the LS manifolds they have long runners. The real difference is the size of the runners and the ports. So while you may gain upper RPM hp and torque from gutting and porting your intake you will loose some bottom end torque. This can be made up some by changing cams or even the converter to take advantage of the new torque curve. These intakes may be restrictive but they do make gobs of torque on the bottom end but they just can't flow enough volume to breath as good on the top end. Don't flame me I am not saying that they can't make power, they just can't flow enough to keep up with a really good set of heads.

 

[Boost231]

^ i agree.. as for them not being able to flow enough to keep up with a good set of heads.. well i know the intake can.. just depends how much you want to work on the intake so it does