Northwind 4150 intake
 

Hi,

I want to go with a Northwind intake with seperated water crossover and wonder how it compares to the performer RPM on the street.
Car is a 66 GTO with 462cui, 236/242/144 HR cam, E-heads, Sniper EFI, 3.55 gears and a 4 speed Muncie. Should be around 500 or a little more hp.

Some say that the Sniper likes the single plane manifolds better. I think the torque will be a little less down low but I hope to gain some power higher in the rpm range. I also like the looks and the fact that the water cannot transfer the heat to the intake. I'd get it port matched, so that should be another benefit.

Maybe someday the heads will be ported and I'll step up to a little bigger cam.

What do you think? Will I at least get the same power or more out of the Northwind over the performer RPM?

Chris

I think the Torker 2 would be a better comparison. I've run 10.90s @ 124 in a 3750 lb car with one. Unless you get the heads ported larger than 2.300 port size it will work. larger needs some material added on top of the ports. I think the larger runners of the Northwind may be not quite as good a match. It looks like a good intake though.
And if you want to go multi port injection they have one ready for that.

We are running Snipers on both dual plane and single plane intakes and don't notice any difference at all in drivability or tuning. Works fine on both.

If you are worried about torque, I wouldn't.

A 462 Pontiac has that in droves so going single plane you likely won't miss it. It may help with some HP up top but if you don't spin it that high anyway it's probably not really much of a discussion.

I will say though, with the water crossover separated, intake swaps become a simple 15-20 minute process. I'd have the car on a dyno and compare the 2 back to back.

I think as long as you're TBI, the general stereotypes apply. You'll likely lose some low speed torque going from rpm to Northwind. Will you spin it high enough to make up for it up top? Only you know. I used one, and liked it. If they'd had them ready for injectors at the time I'd likely still be using it. I can say that with my TBI on the Northwind roasting the tires in low gear was NOT an issue. If you buy one, get one that's ready for injectors in the port. You can plug them for the TBI, and have the option for mpfi later. FWIW

As far as the port match is concerned there should be no issue with your unported Edelbrock heads. As Skip reported the other day the as cast Northwind ports are 2.180 x 1.180.


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From my dyno testing the Northwind didn't show gains over the RPM until 5300+ and the gains maxed out at 15hp. The RPM showed a lot bigger gains below 5300rpm vs Northwind

Very interesting, not quiet far from what I expected, but I guess I really just have to decide if I want more power down or up in the rpm range.
Good to know that Snipers work about the same on both intake types.

The Torker 2 is also nice, but if it wouldn't be clearly better than the Northwind I prefer the Northwind because of it looks and the seperate water crossover.

It is RAIV matched as it comes and I believe that my 1233 gasket from Felpro is about the same size... maybe it won't need much work to match the gasket.

I don't understand how I would do the port matching.... If I make the intake the same size as the heads but still use the 1233 gasket, I could make the intake fit to the gasket and get the same result? Or do I miss something?

Edelbrock gasket information here:

https://edelbrock-instructions-v1.s3...rock/61595.pdf

According to Edelbrock the as cast Performer RPM intake port exit dimensions are 1.100" x 2.060"

I've always been under the assumption the FelPro 1233 gasket is about 1.180" x 2.200"

Might be of interest:

https://www.youtube.com/watch?v=izhxm2vk6Jo


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Easy enough to cut a T2 crossover off.

Yes that Felpro gasket is about what my 4500 Northwind came in with.

455s do not have any problem making tq with a single plane.
That said i do not think you will get anything over the RPM unless you change the cam and bring your RPM range up.

If it will work fine with the current setup I think I'll do the swap, since I'm planning to get a bigger cam someday (+some head port work).
Maybe I keep the RPM intake, cut out the water crossover and can easily switch intakes if I want to compare them on a dyno or the track.

Whichever Intake your going to get if purchasing new, do it now before the cost of them shoot up any more then what they have already!

Also do not sell your dual plane until your 200% sure the single plane is your cup of tea so to speak!

If with your combo now the single plane works all around better, then once or if you port the heads you will still be happy.

Thanks Steve, thats a good advice. I also think it would be better to keep it.
I could work on the RPM while it is unused and cut the crossover + do some port work and have it ready, if I ever need it :) Looks like they are already much more expensive than when I got it.

I was running the RPM intake for several years. I went with FAST 2.0 and the northwind intake ported for my heads. What surprised me was the bottom end seemed to be much better with the single plane. I was told at the time that you could have burbles (from unequal pressures) with the dual plane and could minimize that by gutting the center runner like a Gap intake to equalize pressure

Pokey1 I am all on board with solid empirical evidence like you have had when you swapped intakes, but the stuff about burbles and pressure difference in a duel plane intake the way it’s was discribed to you sounds like someone was blowing smoke up your Butt hole!

I've always found a pinch of power on those RPM air gaps by installing a 1" open spacer. That basically is like removing some of that divider and adding a little plenum volume at the same time without cutting anything. It's a simple change that tells you right away if it's heading in the right direction without modifying something that is difficult to reverse.

I don't know why the Pontiac RPM air gap intakes come with a full divider but on other engine models the RPM air gap intake has the divider already cut down. Always thought that was strange.

It's been shown on the dyno that taking the divider down about 1 inch on the regular RPM intakes to mimic the air gap, picks up power. I've seen that outcome on several different types of engines. I'm sure it does affect fuel distribution to some degree.

We saw pretty good gains on the dyno with open spacer on RPM intake. After trsting i wouldn't run a RPM without at least a 1/2" open prefer 1"+

I was told it would work but I can either cut the divider or add a spacer so there was a gap between the 2 sides. It would run better that way if I wanted to use the dual plane. That was from Butler.

When I was running a carb I had the engine on a dyno and just by adding the 1" spacer on the RPM and not changing anything else there was a 20 hp difference. I always used the 1" after that on the RPM.

I would not be so quick to dismiss Pokey's comments. We had my 467 with throttle body Holley EFI/Northwind/ported E heads on the engine dyno, and we also noticed some strange behaviour at low and mid range, right around 1700-2500 rpm. We did not have an intake to compare to during that dyno session, so I can't say if a dual plane would have been better in this range- but it would not surprise me.

The engine seemed to "waffle" and had audible stuttering when under load in that rpm range. The cylinders impacted were # 6 and # 8, towards the back of the engine.

The theory put forth as to why this was happening was accredited to poor fuel distribution of the Northwind when used with a throttle body EFI. The EFI disperses fuel under high pressure in an annular ring of small holes adjacent to the throttle blades. The theory that Steve Brule advanced was that when the throttle blades were partially opened, they deflected flow away from the back cylinders. He thought that a 1" spacer would help, but we did not test as it barely fits under the hood as is.

We did manage to tune out most of this, but I feel the engine was down ~ 20 peak hp over what I would expect with a Torker II. Even with the tuning, I can still feel some of this in the car when I drive it.

My advice if considering a Northwind is to use it for port injection, not throttle body EFI, if I had it to do over I would have used a different intake.

That's a pretty significant difference. I've never seen that much on an RPM air gap intake with a 1" open. Usually single digits, 7-8-9hp.

The most gain I've seen with a spacer is dad's engine with the Victor intake, using a 2" tall super sucker (4 hole taper spacer) it picked up 18 HP.

The dyno tests you've done with rpm intake, they were Pontiacs?
We saw double digit gains on the dyno just like pokey1

412 CID / #16 d-port heads / 251/262 @.050 - 108 LSA solid roller
Performer RPM intake w/ Brad Urban Holley carb rated 926 cfm
Intake port matched to the heads and plenum divider cut down 1-inch

With no carb spacer:
535.7 ft.lbs. torque at 4800 rpm
555.1 HP at 6500 rpm

With 1-inch open carb spacer:
541.5 ft.lbs. torque at 4800 rpm
560.5 HP at 6400 rpm

Edit w/ Side note- Engine Masters did an episode where they did a carb/EFI comparison where they used the Sniper EFI (not Pontiac). They had all sorts of problems with the dual-plane intake and it ended up being some sort of airflow/fuel distribution problem. They gave up with it and went on to the testing with a single-plane intake, with no issues. That said, if I remember correctly Steve Brulé stated later if he took the time later it might of helped the situation with some tuning on the dual-plane intake.




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Given that a TBI is basically a really fancy carb, I'm not sure why the intake manifold design would make a difference between the two?

If a particular manifold is creating distribution problems with a TBI, wouldn't it also cause the same problems with a carb? What am I missing?

https://www.youtube.com/watch?v=MQP0...nnel=FitechEFI

Same principle as the Holley EFI throttle body EFI.

Pontiacs and Chevrolets. I like to use that RPM air gap intake a lot for street car stuff. I've wanted to experiment with other types of spacers on that intake, just haven't gotten around to it.

Now that is pretty typical of what I see with that intake and adding a spacer.

You would be in the ball park with that thought process Will, in my opinion.

As I mentioned earlier in this thread, we are running Holley Sniper Stealth's on 2 different cars, one with a single plane, and the other with a dual plane.

They are both working very nicely on both engines.

The dual plane is an rpm air gap with a 1" open spacer.

The single plane is a Victor with a 4 hole taper spacer (super sucker)

Neither car exhibits any funky idle or drivability issues. They both hold any commanded AFR I choose fairly consistently, and the plugs all appear to burn pretty evenly. I'm guessing not everyone has this kind of success with these throttle body deals just based off what I've read, but it works really well for me.

One thing I do miss about the carbs that were on both of these cars, was the ability to stagger jet, which helps a bit on those dual plane intakes. Oddly, even with EFI technology and the advanced software, you don't have that ability on the throttle body units. I would have liked that option, to maybe change injector pulse width in one or more corners of the unit. No reason they couldn't incorporate that into the software.
Multiport Injection gives you that ability. ;)

I was able to find it recently and watched it without fees or subscribing. It was a very interesting presentation with some interesting comments from Steve Brulé regarding the difference in fuel distribution.

Engine Masters Ep. 2: Carburetor vs. EFI Shootout on the 5.3L LM7

Try this link:

https://www.dailymotion.com/video/x3klp5c


Keep in mind they did not try a couple different spacers under each setup. This can have a big impact.

( Information provided in this video does not represent any endorsement by me ! .And unless specified it is not based on personal experience and is offered for general interest only. I'm not here to sell Holley parts or FI systems ! )


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