Gasser intake swap

[Antebios]

Hey I've seen a few N/A 1.6l with gasser intakes on them. They look like it might be getting some more air or at least colder air then the stock N/A airbox and intake.
Anyone know which intake manifold is used for this?

[chrissev]

Hey I've seen a few N/A 1.6l with gasser intakes on them. They look like it might be getting some more air or at least colder air then the stock N/A airbox and intake.
Anyone know which intake manifold is used for this?

do you have the old style N/A intake with the filter on the front of the intake, right above the valve cover, with the little tube coming out the front where the air goes in?  I've seen people drill those intakes full of holes to get more air than the tube allows.

[vwmike]

Hey I've seen a few N/A 1.6l with gasser intakes on them. They look like it might be getting some more air or at least colder air then the stock N/A airbox and intake.
Anyone know which intake manifold is used for this?

do you have the old style N/A intake with the filter on the front of the intake, right above the valve cover, with the little tube coming out the front where the air goes in?  I've seen people drill those intakes full of holes to get more air than the tube allows.

Something tells me that drilling holes in the airbox would just be pissing in the wind. The thing about the gas intake is that it has shorter runners so intake velocity would be lower. So, you'd gain a little top end at the expense of low/mid-range torque. But, how much top end? I would guess not a lot. The valves are pretty small in a 1.6D.

[racer_x]

I have my doubts about the "drill holes" in the airbox approach. At best you'd be sucking in hot air which doesn't help power much at all.

On my normally asthmatic 1.6D, I have cut the front of the air cleaner and installed a 3" thinwall PVC pipe. The pipe points over toward the bell housing end of the engine. I'm acutally using a gasser valve cover and I've rigged the throttle cable support to fit under the pipe and support it so that vibration/fatigue isn't as much of an issue. I have a 3" flexible duct attached to the end of the pipe, and the other end of the flexible duct is attached to a plastic flange with a 3" thinwall PVC pipe on it that's bolted to the firewall above and just to the right of the master cylinder. I've cut a hole through the front part of the "rain gutter" to match the pipe inlet. So I have a "cowl induction" setup on mine. The air at the base of the windshield is at fairly high pressure relative to under the hood. It might give a slight power advantage at highway speeds.

[chrissev]

I have my doubts about the "drill holes" in the airbox approach. At best you'd be sucking in hot air which doesn't help power much at all.

On my normally asthmatic 1.6D, I have cut the front of the air cleaner and installed a 3" thinwall PVC pipe. The pipe points over toward the bell housing end of the engine. I'm acutally using a gasser valve cover and I've rigged the throttle cable support to fit under the pipe and support it so that vibration/fatigue isn't as much of an issue. I have a 3" flexible duct attached to the end of the pipe, and the other end of the flexible duct is attached to a plastic flange with a 3" thinwall PVC pipe on it that's bolted to the firewall above and just to the right of the master cylinder. I've cut a hole through the front part of the "rain gutter" to match the pipe inlet. So I have a "cowl induction" setup on mine. The air at the base of the windshield is at fairly high pressure relative to under the hood. It might give a slight power advantage at highway speeds.

That's probably better than just drilling holes.  The intake on those cars is actually in a horrible place because it takes its air from right on top of the engine, which tends to be kind of hot.  The idea would be to make as big a hole as you can in the air box then route the intake somewhere where there is likely to be cool air.  The turbo cars take their air from the side of the engine bay through a hole and that seems to give cool enough air, though it heats up quite a bit when it goes through the turbo because it is close to the exhaust.

[Antebios]

Im talking about running a gasser intake manifold on the diesel engine, i think its the rabbit gas intake that fits but im not sure. I want to use a cone filter on it, and route it behind the battery. My dad wont let me cut the airbox apart to put a bigger intake pipe on it.

So i was just wondering what intake manifold is used for that.

[jtanguay]

you can buy the cheap cone filters off ebay, thats what I did, but now I have to fab some sort of box for it so that the hot engine air doesnt get sucked into the intake .   I just took the whole airbox right out

[VWRacer]

I'll take a look in the engine compartment of my Mk1 GTI tonight, and let you know if any ideas hit me.

[fspGTD]

Any intake manifold off a VW 4-cylinder crossflow, transversely mounted engine should bolt up to your VW diesel head and fit within your engine compartment, as long as it's not the kind that has fuel injectors mounting to the manifold.  The diesel head sits in the same location as a gasser cylinder head and has the same intake ports and bolt pattern.

Volumetric efficiency comparison of a 1.5 liter diesel vs 1.6 liter gasser, euro GTI heron head model (same intake manifold as a A1 gasser short-runner application), taken from the VW 1.5D SAE paper:

The naturally aspirated diesel's induction system, including it's intake manifold design, plays a role in achieving the diesel's superior volumetric efficiency of 92% between 3000-4000rpm.  The gasser manifold is probably tuned to allow help the motor to achieve it's volumetric efficiency peak at a higher RPM of 4500-5000RPM.

What are you and/or your dad hoping to achieve by swapping out your diesel intake manifold?

I wouldn't expect a short runner gasser manifold to give any benefit unless you plan on using very high RPMs often, and it will likely hurt power and torque at rpms below that point.

If you are looking for a cold air intake, I would recommend adding the cold air baffle and snorkel found in Rabbit automatic transmission diesel models.  You could also use a TD air filter (they are thicker) for lower resistance of the air filter element, although I don't think it would noticeably benefit a naturally aspirated diesel.

If you want to really kill your torque, try swapping on a TD manifold on there.  :lol:  (Actually, if you were to try this, I would be really interested in hearing the results.)

[Antebios]

I found the post that some other guy did. He used a 1.8l intake manifold and a short intake tube with a cone filter. I/m trying to see if i can get more air into the engine and also trying to get cold air thats not coming in off the top of the engine
Tell me what you think.

http://www.vwcaddy.com/topic.asp?TOPIC_ID=4070

[VWRacer]

I think it would work fine and be a lot of fun. Here's a couple of pics from the engine bay of my Mk1 GTI.



You can see the intake manifold at left with its snorkle heading off to the air cleaner at right just aft of the battery tray.

In the photo below, I am looking almost straight down. If you ran a 3" intake pipe over here you could then drop it down into the undercar air to avoid injesting the hot underhood air that the caddy photos show his engine getting.

[Antebios]

Yeah thats what i wanted to do, run it down under the car where that space is.

Would a g60 intake manifold provide more air?

[fspGTD]

As stated in the thread you referred to, it's an A1 fuel injected gasser manifold.  A G60 manifold has the same runner lengths as the A1 gasser, but larger runner diameters, so the G60 may allow more high-rpm flow.  However the downside of the larger runner diameters is that peak velocity and therefore air inertia is lower, and so should be the boost to volumetric efficiency at the tuned RPM.

I don't see any evidence of scientific testing being done supporting the hypothesis that this change would actually increase performance.  The guy writing about it has no baseline test, so his feeling that this helps performance is not reliable.

If you are considering doing this mod for performance reasons, I would urge you to do some testing before vs after of some sort, and report back on this thread with your results.  That way, you will know if it helped and how much (or if it hurt and how much) and everyone can learn from your experiment.  I would highly recommend doing back to back runs (comparing OEM baseline vs alternate manifolds) with an RPM-sensing G-tech or a chassis dyno if you can swing the cost, capable of plotting hp and torque vs RPMs.  That way, you can see how the modification impacts performance along the entire RPM curve.

Also, I would strongly urge you to use an inline style air filter setup to intake air from in front of the radiator, rather than to intake air in the hot engine compartment which can tend to be hot.  In my experience, inhaling hot air from the engine compartment can easily cost 4% power and torque throughout the RPM band.  Which would pretty much guarantee the manifold would performance worse than a stock manifold ducted to cool air like the OEM automatic tranny naturally aspirated diesel setup would provide you.  HTH... good luck.

[jtanguay]

check out what this guy did

http://www.virginiovejjet.50megs.com/

To me, that sounds like the best idea (makes it look a little rice, but who cares??)

[fspGTD]

And then there is Roger Brown's cold air setup:


It looks to be functionally equivalent to the factory Rabbit diesel Automatic cold air intake tubing and cold air baffle that mounts behind the passenger headlight.  I priced the parts for this factory cold air setup out on impex by the way, and the pieces are all available for under $40.