intake porting "Big Dogs"

Just for the sake of putting it here, this is what the runners on my Extrude Hone lower looks like. I think this was in later-1998, when I was running the Kenne Bell supercharger.

It left a very smooth surface. There's all kinds of discussion about smooth vs not, and I personally believe it makes a significant difference in the intake port, where having a boundary layer due to the "golfballing" can reduce the amount of fuel that sticks to the port walls, but not so much in the intake runner of a port-injected vehicle.

The real limiting factors on the GT-40 are the runner lengths and plenum volume, and to some degree the throat size, especially for a naturally aspirated combo. There's nothing you can do to make the GT40 make power above ~5300-5500 rpms. It falls off a cliff at that point. Up to that range, it's a good intake, especially with boost. I had my cam made with that in mind, still use the stock throttle body, and have been pretty happy with the way the truck runs in all conditions.

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Just for the sake of putting it here, this is what the runners on my Extrude Hone lower looks like. I think this was in later-1998, when I was running the Kenne Bell supercharger.

It left a very smooth surface. There's all kinds of discussion about smooth vs not, and I personally believe it makes a significant difference in the intake port, where having a boundary layer due to the "golfballing" can reduce the amount of fuel that sticks to the port walls, but not so much in the intake runner of a port-injected vehicle.

The real limiting factors on the GT-40 are the runner lengths and plenum volume, and to some degree the throat size, especially for a naturally aspirated combo. There's nothing you can do to make the GT40 make power above ~5300-5500 rpms. It falls off a cliff at that point. Up to that range, it's a good intake, especially with boost. I had my cam made with that in mind, still use the stock throttle body, and have been pretty happy with the way the truck runs in all conditions.

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What heads are you running?
 
20 year old CNC'ed AFR185s. No idea if they're still comparable to the heads AFR makes today. I had Fox Lake Twisted Wedges on it when I had the lower intake done.

Back then I was trying a LOT of different combinations.
 
No idea if they're still comparable to the heads AFR makes today.
A local porter here speaks very highly of AFR's continuous product improvement. He built an engine for the Engine Masters years ago with a set of AFR heads on it and their same model head out of the box today is better than his ported head from years ago.
 
lord i don't miss porting one bit.........i'll do it on my chainsaw/weedeater/jetskis etc........but my last one subaru sti, i ported everything, took forever..............but made a difference, but long nights in the shop after the kids went to bed........i'll never do it again, nor custom paiting.........it came out to like 5 bucks an hour lol

the whole smooth vs rough has been a debate on a lot of stuff.........don't think ive seen a dyno shootout of smooth vs rough, carb or efi.

you know in the jet ski world, all the intake manfiolds come with a flame arrestor insert that looks like a catalytic converter to suppress a backfire situation, and you would think this would choke the living dogg out of the engine, but every one ive removed seemed to make no difference in performance.1654789170467.png
 
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I use an air straightener in front of the MAF on my Chebby that looks like a piece of honeycomb. Made a huge difference in the low speed MAF signal stability and supposedly doesn't make any difference in max flow. It's in a 5" pipe, so there's plenty of flow headroom on my ~700 hp combo.
 
you know in the jet ski world, all the intake manfiolds come with a flame arrestor insert that looks like a catalytic converter to suppress a backfire situation, and you would think this would choke the living dogg out of the engine, but every one ive removed seemed to make no difference in performance.
It's because they're not right at the cylinder and they have other things that are a bigger restriction between them and the cylinder.
 
I use an air straightener in front of the MAF on my Chebby that looks like a piece of honeycomb. Made a huge difference in the low speed MAF signal stability and supposedly doesn't make any difference in max flow. It's in a 5" pipe, so there's plenty of flow headroom on my ~700 hp combo.
How close is it to the maf?

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It's because they're not right at the cylinder and they have other things that are a bigger restriction between them and the cylinder.
what do you mean not right at the cylinder? those go right on top of the throttle body's, each cylinder has its own TB. not restrictive at all
those are off of a yamaha fxho, five valve per cylinder engine, capable of over 14K rpm......
 
I use an air straightener in front of the MAF on my Chebby that looks like a piece of honeycomb. Made a huge difference in the low speed MAF signal stability and supposedly doesn't make any difference in max flow. It's in a 5" pipe, so there's plenty of flow headroom on my ~700 hp combo.
yeah, they make no difference in performance on the jet ski's but are required by law to suppress a backfire, kawasaki had a HUGE recall because they didn't put them in at the factory........i can't tell you how many of those i did....ive seen a few motorcycle engines with them as well as land vehicles.

so back to airflow..............shortest distance between to points, ive ported V shaped channels on the bottom of the intakes ports to shorten the intake tract runner with great results, and matched the cylinder head as well.......the two strokes really perform good with them as well as an air break up thingy.........can't remember what they call it, but it bolts under the carb with two gaskets and has a bunch of twisted knife blade looking things in the intake to create more friction so the carb can atomize better..............and believe it or not, works great.
 
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About a half inch upstream. I have a velocity stack inside of the filter attachment, then the honeycomb, then the MAF meter.
It's a slot/card style MAF.
Hmmm. I wonder how well it would work on my built gen 2.

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This is disappointing to hear. I sent my intake to Big Dogs in February for a STG3 and keep getting the same boiler plate responses. I really hope it doesnt end up taking as long as I am hearing. My build isn't ready for the intake yet, but i hope this doesnt end up being a hold up.
 
This is disappointing to hear. I sent my intake to Big Dogs in February for a STG3 and keep getting the same boiler plate responses. I really hope it doesnt end up taking as long as I am hearing. My build isn't ready for the intake yet, but i hope this doesnt end up being a hold up.

Sounds like you'll have to do what Jonathan did and really put pressure on them. Keep us posted!
 
I did some research on them when they weren't answering me. I think he also owns BigDogs Custom and Collision. I found a phone number online for that business. Haven't tried calling it yet. Trying to be patient.
 
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I use an air straightener in front of the MAF on my Chebby that looks like a piece of honeycomb. Made a huge difference in the low speed MAF signal stability and supposedly doesn't make any difference in max flow. It's in a 5" pipe, so there's plenty of flow headroom on my ~700 hp combo.
Those were OE on GM products for years. People used to remove them to improve flow and then wonder why their car ran like crap.
 
what do you mean not right at the cylinder? those go right on top of the throttle body's, each cylinder has its own TB. not restrictive at all
those are off of a yamaha fxho, five valve per cylinder engine, capable of over 14K rpm......
I mean they aren't right at the cylinder. It's several inches from the cylinder to the flame arrester. Even if they were a slight restriction you probably couldn't tell because the volume of air between them and the cylinder is relatively large and can be refilled when the intake valve is closed.
 
yes, your right, there is plenty of volume between the two..............removing it makes no difference. ive never seen one in any of my chevy's though. but obviously they work or oem would'nt put them in....
 
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