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I lost 1 lb. boost and gained approx. 4 hp and 10 ft-lbs torque. Boost dropped from 15 lbs in 3rd/4th to 14 lbs. "How is this possible?" With my port-matched exhaust manifold that I installed Saturday at my house while the Colorado crowd was changing all their timing belts. Note that this dyno chart is not SAE corrected and the absolute numbers are questionable, but the relative values should be good:


I got this from cypher2K on the 'tex - it was a homemade job for $125, and I am very pleased with it. It is technically a "gasket-matched" manifold, where the ports on the manifold are matched to the gaskets. Also, the inside of the runners were shot-peened; a "poor-man's" extrude honing. The exhaust ports on the cylinder head were just about perfect as-is - they were almost exactly symmetrically 2mm smaller than the gasket holes.

Unmatched Exhaust Ports (compared to gasket):


Unmatched Turbo Flange (compared to gasket):


Matched Exhaust Ports:



Matched Turbo Flange:



Driving Impressions? I kept telling people this week that "it's either deceptively fast or else it's slower than it used to be." I think the dynos prove it's not slower. There is now a much smoother transition into boost, the engine seems to run smoother, everything power-wise is just effortless.

Why the reduced boost? I see two reasons:
1) The port-matching at the turbo inlet caused the exhaust port to become larger. This reduces the velocity right at the turbo inlet, compared to what it was with the smaller opening. So boost is reduced.

2) Better volumetric efficiency = less load = less for the turbo to push against = less boost.(?)

I'm at the max efficiency of the turbo with this setup. My MBC is set to where I'd get 20 lbs boost, if the turbo would give it. With the port-matched exhaust + Random CAT, the only restriction left is the stock exhaust... I imagine that when I finally get an exhaust, it will wake the turbo up to another 3 to 5 lbs boost. (drool, drool...)
 

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You still have the stock exhaust?? :)

Good to hear about the gains. You portmatched the turbo to the manifold only, or did you do the manifold to exhaust ports as well?

-Ian
 

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swett said:
You still have the stock exhaust?? :)

Good to hear about the gains. You portmatched the turbo to the manifold only, or did you do the manifold to exhaust ports as well?

-Ian
Yup - I've gotten rid of all the restrictions except the very last one (exhaust), so when I finally get rid of it, it's gonna POP! :lol: The exhaust manifold has been port-matched to the turbo and the exhaust ports. You'll see good pics next week.

not_too_shabby said:
so what were your #'s?
The numbers on these two comparison runs were about 170 Torque, 150 HP, at the wheels, SAE. These were VAG-COM dyno plots, so the absolute numbers are questionable. The best numbers my car has produced on a "real" dyno are 216 Tq, 165 HP at the wheels, SAE corrected.

aldolicious77 said:
was it colder out,,the weather always lays a factor with our turbos
Ambient temp was 49-51F both days.

x said:
My advice is to stop playing with these 4hp gains and just get a real turbo...hehe j/k. Good job Rusty
Thanks! heh-heh-heh... eventually I'll have a K04 running with my stock ECU. But that's a year or two, and a bunch more tweaks and learning, away...
 

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my only guess is that the same amount of air is now in a larger space decreasing pressure. I think you have hit the end of your turbo, a bigger turbo will really take advantage of all that port matching. My guess, the K04 will give you bigger gains than anyone else becuase of the larger intakes. :thumbup:
 

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UPDATE - I took the car on a road trip. The difference is amazing.

BEFORE: When cruising on the highway, I could tell when the car was creeping into boost, like when keeping a constant speed up a hill, or encountering headwinds, etc. I was just "aware" of it by the feel of the motor, or something, and I'd look over at the boost gauge, and sure enough, I'd have boost, a couple to five lbs.

NOW: It is so damn smooth it's scary. I'm NOT aware of boost under those situations. It is so smooth and quiet. I'll be cruising along effortlessly and look over and holy cow! 2, 3, 5, 8, up to 10 lbs of boost without awareness. Acceleration to high speeds is accomplished without a lot of "strain" from the engine.

It has been said that this mod can decrease EGT by 200F. I think this may be true as evidenced by my oil temp gauge...

BEFORE: cruising under constant boost (as under a load up repeated hills or cruising at speeds that require constant boost) would very quickly spike the oil temp up to 240+. Also dyno runs, etc.

NOW: I can't get the oil above 230. No matter what I do. Even constant cruising for a long time at 10psi+. The true test will be next track day, hopefully April. Track usage always gets the oil temp up to 260F...

This also may be due in part to switching from 10w-40 to 15w-50, but I guess I'll never know what percent is what. Feeling a lot less like I need extra oil cooling, now. :thumbup:
 

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How much would it cost to get an OEM exhaust manifold?... used or new?...

I want to play around with a spare one and have it fit when things look good.
 

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Hey Rusty, bumping this back up to the top.

I was checking out my stock exhaust manifold and you're right, its substantially off. The KKK turbo was perfectly matched to the gasket, but the stock manifold clearly had much larger tolerances and could be used being opened up. The exhaust ports on the head were perfect, but the exhaust manifold looks like it could be a bit small. From what I hear, having the exhaust manifold even slightly smaller than the exhaust ports on the head is very bad, because it can cause reversion.

It seems like an extrude hone and then a portmatch would be the perfect combination for this manifold. Since the heads and turbos appear to be very accurate, someone could even do these and resell them without having to portmatch it to each person's car individually.

I guess this is all caused by the difference between the tolerances when machining(very tight) versus casting(very loose).

-Ian
 

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So Rusty, how much of a bugger was it to remove the manifold? Your pictures tell a new story that your words alone didn't! That is really amazing the difference beteen the gasket and the manifold. Nice job! :)
 

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Interesting mod Rusty. Do you think it will affect the life/performance of the gaskets with the matched ports now?

OK, I observed all of you have US spec cars. Now my question. Slightly off topic.
How many of you have your cars' temp gauge reading above 190F? Mine never budges beyong 190, just want to make sure my temp sensor is doing fine.
 

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Discussion Starter #17
swett said:
...The exhaust ports on the head were perfect, but the exhaust manifold looks like it could be a bit small. From what I hear, having the exhaust manifold even slightly smaller than the exhaust ports on the head is very bad, because it can cause reversion...
Yeah, you want the manifold ports to be about 2mm larger than the head ports.

swett said:
It seems like an extrude hone and then a portmatch would be the perfect combination for this manifold. Since the heads and turbos appear to be very accurate, someone could even do these and resell them without having to portmatch it to each person's car individually.
Yup. The places that do this, though, are charging $400 or so...

Chas said:
So Rusty, how much of a bugger was it to remove the manifold?
It was ridiculously easy. I was afraid I'd have to take the turbo out (disconnecting oil lines, etc.) but no! Just unbolt the top three turbo bolts to the manifold, and that's it! It may help to loosen the spring bolt on the downpipe. And it definitely helps if you remove the airbox - lots more elbow room that way. I was very pleased with how easy it came out and went back in. And yes, I followed recommendations and got three new turbo-to-manifold bolts.

YetAnother20V said:
Interesting mod Rusty. Do you think it will affect the life/performance of the gaskets with the matched ports now?

OK, I observed all of you have US spec cars. Now my question. Slightly off topic.
How many of you have your cars' temp gauge reading above 190F? Mine never budges beyong 190, just want to make sure my temp sensor is doing fine.
I think it will definitely affect the life/performance of the gaskets - they should last longer because of reduced EGT's. And your temp sensor is fine. They design the gauge to stay at 190 to appease the masses of non-enthusiast people who would freak out if the gauge were accurate.

04b51.8t said:
thanks for the post....what did you use to match the ports?
Paypal. Seriously. There was someone on Vortex who bought this manifold for his transverse 1.8t, had the ports matched, etc., then discovered it wouldn't fit his engine. $125. It was for sale for a couple of months before I finally snatched it up!

If I had to match the ports myself, I'm not sure what I'd use, since it's cast iron. I have a Dremel w/tungsten carbide bit that was great on my aluminum intake, but I'm not sure how it would work with cast iron. Anyone out there know?

...

My oil temps still remain incredibly stable, never topping 220F. The final test will be this Saturday the 15th, at the track. I'll post results next week.
 

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Rusty, the tungsten carbide bit will work fine I think. The cast iron didn't seem that much harder than Aluminum when I was using a grinder wheel on it.

So even if the rest of the runners aren't enlarged, you think its good to enlarge the manifold ports to the gasket size? I'm not really sure what the tradeoffs between step size and power are. I'd be concerned about opening up the manifold too much and having it step out, then immediately constrict back to the normal size. I know that is a potential problem with gasket matching.

I guess none of this applies to you, since yours was shot-peened, which probably opened it up a bit.

-Ian
 

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I don't think the shot-peening did that much. Even if you don't open up the runners, there are still obvious benefits to opening up the ports - just like the intake manifold, getting rid of sudden steps that cause turbulence is a big help. If it's ported right, it won't immediately constrict back - it will be a gradual transition.
 

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my addition to the thread:

-I had my exhaust manifold Extrude-Honed. They smoothed the interior out. I gasket matched it myself with a dremel after the extrude hone.

before gasket matching


note the black magic marker around the areas to be removed. I layed the gasket over the port then colored the areas to be removed...that way i didnt have to keep checking with the gasket during the dremeling.


during




after


before gasket matching

after

 
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