intake ports on a 5.7 hemi

[5.7 hemi]

As I was talking with Dave Weber at modern muscle about putting a 6.1 intake manifold on my 5.7, I told him I have spacers that are 1.5 inches tall to get clearence over the timing cover and usinf an LX 5.7 manifold and I find what he said a tiny bit odd at the least.

He said that I shouldn't be using a spacer so big cause it will screw up the air flow and wont line up right with the ports. I'm calling this b.s. cause the ports are vertical to begin with and with the spacers, my runner length is longer giving me more low end. Now if I use a 6.1 manifold, I'll have to do some port match on the top of the spacers to match the 6.1 and blend it all in....no biggie on the cnc.

Now the only reason I'm considering this is purely for eye candy, even though the 6.1 manifold has shorter runners, the spacers will add to the overall length and I shouldn't lose any power down low or the upper end.

So, what do you guys/gals think? Am I just that stupid or was Dave not thinking clearly?

 

[64 AAR Valiant]

Just try it what do you have to lose. In theory it sounds plausible.

 

[rapidtransitric]

As I was talking with Dave Weber at modern muscle about putting a 6.1 intake manifold on my 5.7, I told him I have spacers that are 1.5 inches tall to get clearence over the timing cover and usinf an LX 5.7 manifold and I find what he said a tiny bit odd at the least.

He said that I shouldn't be using a spacer so big cause it will screw up the air flow and wont line up right with the ports. I'm calling this b.s. cause the ports are vertical to begin with and with the spacers, my runner length is longer giving me more low end. Now if I use a 6.1 manifold, I'll have to do some port match on the top of the spacers to match the 6.1 and blend it all in....no biggie on the cnc.

Now the only reason I'm considering this is purely for eye candy, even though the 6.1 manifold has shorter runners, the spacers will add to the overall length and I shouldn't lose any power down low or the upper end.

So, what do you guys/gals think? Am I just that stupid or was Dave not thinking clearly?

zac

are you sure you want to do this, before you get you fuel consumption dilema figured out? this may add to the fire. how about flow patterns and stats between the two manifolds? will you again have to have you pcm retuned.? and you just swapped out your injectors. have you given that current combination a chance at being dialed in to its potential. solve one part of the equation before adding something else to it. otherwise imoa you'll never get it worked out :-k

 

[5.7 hemi]

Yeah I know, but the idea is so sweet looking. So far the smaller 5.7 injectors seem to be doing just fine. Since I have the 03 computers, tuning is just about impossible without a dbr111 or starscan. My local dealer doesn't know their head from their rectum and wont hook up their scan tool without me providing a vin#, which I dont have.

I also have come to figure that whatever I get as far as mpg is whatever it's going to be, the only other thing I can change is the vette filter/regulator and since everything was new when I built the car I doubt the filter/regulator is clogged.

 

[Uhcoog1]

The LX guys who run a 6.1 mani on an unported set of 5.7 heads use a spacer themselves (to match ports). I wouldn't worry too much about the additional runner length, though I'll have to look again to see if there ends up being a kink in flow. If I remember correctly, the intakes are still at 20 degrees or so from vertical.

 

[Tincup]

zac

are you sure you want to do this, before you get you fuel consumption dilema figured out? this may add to the fire. how about flow patterns and stats between the two manifolds? will you again have to have you pcm retuned.? and you just swapped out your injectors. have you given that current combination a chance at being dialed in to its potential. solve one part of the equation before adding something else to it. otherwise imoa you'll never get it worked out :-k

Ditto....:banghead:

 

[03ramit1]

Why not just mill the timing cover, and build a relocation kit for the alt and ac compressor? And port match the heads to the 6.1 manifold. Inertia sells the relocation kit. And it would save you the hassle of designing it yourself.

 

[5.7 hemi]

I have the spacers already cnc'd and the alt, ac has been moved already cause I'm using an lx manifold now so the 6.1 would be just r&r and some whittleing on the spacers to match the 6.1 ports.

 

[5.7 hemi]

Alittle eye candy for ya guys.....dual inlet intake is 4 inch diameter.

 

[Joe Dokes]

That air filter setup looks very nice.

As far as the spacers, I'd use them, assuming the transition from the larger 6.1L Hemi runner to the smaller 5.7L Hemi intake port is a smooth transition and is not too abrupt the only thing it will do is lengthen the intake runner length slightly.

Assuming the spacers are 1/2" to 1" thick the only thing it will do is change the torque curve of the motor slightly. Ideally the runner length is tuned to so that you get a reversion or ram effect at the torque peak of the motor.

Thus, if the runner length is longer the ram effect will be at a LOWER rpm, if the runner length is shorter, the ram effect will be at a higher RPM.

By lengthening the runner slightly you will increase your low end torque slightly, or you'll slightly lower the RPM where the ram effect of the runner length has its biggest impact.

This is why variable length intake manifolds like on the 09-12 5.7L Hemi's and the 2012 392 Hemi's are so cool, it allows a long runner length at low RPM maximizing torque down low, and then as the RPM climbs the computer opens up the shorter intake runners creating a new ram effect at a higher RPM.

Long Story Short, the only place you'll see a real difference by adding a 1/2" to 1" spacer is on a chassis dyno.

Regards,

Joe Dokes

 

[5.7 hemi]

Yep that's right Joe!! I got schooled by my grandpa (chrysler mechanic for 30+yrs) and he remembers the old long ram intakes, hated to work on them, but he said they made so much torque it was insane. So I figure the same will apply to today's efi engines.