Reply With QuoteNice Eski! Didn't know you'd had an RS2000 Sam?
Volkswagenist
oh man despite the full rotisserie resto it still somehow smelt like my old Rs2000. I'm on night shift but if I cant sleep tomorrow morning i'll be down there to hear it at full noise that's for sure.
Volkswagen Fan
Nice Eski! Didn't know you'd had an RS2000 Sam?
Volkswagenist
Yeah all RWD in the early days believe it or not. RA23 Celica GT with the 18R Yamaha twin cam on webbers and a genuine 2 door RS2000. It had forged bottom end and everything from a race cam with 45mm dellortos, to a rally cam with twin 40mm webbers and even a little street cam and one of those single side draft redline inlet manifolds. That's why I get a bit fizzy when I see anything with sidedrafts. Also had an AE71 Corolla that was going to get sprinter/4AGE treatment until I bought a Peugeot 205 GTi 1.9 instead. But then uni/backpacking/marriage/kids put it all on ice until I thought I'd buy a sensible VW commuter....
Volkswagenist
Just found this pic. So its one thing to look at small port vs large port heads and think that the small ports don't look too terrible, but the inlet mani is another thing. This is looking back up a small port vs large port inlet mani. You can tell from the outside of these manis that the injector bosses are really big but check out how badly the injector boss chokes down the small port mani.
Makes you wonder if there's something decent to be had just by going for a large port manifold on a small port head. Using one of the thicker large port - small port step down phenolic spacers to give the most gradual/smooth step downs would have to be better than the small port inlet and cheaper than an aftermarket inlet.
this one is off the shelf
this one looks like a small port spacers being custom port matched to a large port inlet size.
Volkswagenist
http://www.cylinderheadtech.com/flownumbers.pdf
these are flowbench figures of 1.8T small and large port heads including ported versions of each. Its hard to compare the 1.8T's to the honda heads and the others as they are flowed at .450 lift vs .380 but could they have done the 1.8T at the lower lift because they have more valve area being 3v inlets as a way to standardize the readings for comparisons sake?
Not sure what to make of it. I always thought the exhaust ports were the same size regardless of inlet size yet the exhaust flows vary for common valve sizes. whats the go with that?
How do exhaust ports get flow benched. Surely they close the inlet valves and push air into the combustion chamber from below and flow them in the correct direction yeah.
Volkswagen Fan
You've had some cool toys!
Seems like the intake might be an advantage, but why not just go the head at the same time too?
Volkswagenist
My best engine is the one on the stand. Only has 90k km on it. I'm considering not even opening it up and just swinging that in, putting a better intake and the new turbo on it and crossing my fingers re the rods. It could hold together for a long time. The dud engine (the one that will come out of the car) can then be built properly with the large port, rods, S3 pistons, sump etc etc
Other option is to re rod and re head the engine that's in the car (and do it in the car) in which case I would do the head then too.
Volkswagen Enthusiast
I don't recognise it, must be a new one, IP regs don't allow spring type or location change, so has to stay leaf springs.Originally Posted by sambb
Cheers
Gary
Golf Mk7.5 R, Volvo S60 Polestar, Skyline R32GTST
Volkswagen Enthusiast
To do the exhaust ports we used to suck the air through the extractors. block off one cylinder at a time. Measure the vacuum, same as with the inlet by sucking into the combustion chamber.
I can't see the logic is reducing the lift to simulate 3 valves versus 2. For a given bore size the 3 inlet valves will be proportionally smaller (than the same bore size with 2 valves) so it doesn't seem logical to reduce the lift as some form of compensation. Possibly that's all the lift that they can fit without valve interference.
As a generalisation we usually aim for an exhaust flow around 80% of the inlet flow. OEM the Audi 20V look horribly unbalanced, not enough inlet flow and/or too much exhaust flow. Which they have attempted to correct with the porting.
Cheers
Gary
Last edited by Sydneykid; 26-08-2019 at 10:33 AM.
Golf Mk7.5 R, Volvo S60 Polestar, Skyline R32GTST
Volkswagenist
Alright I went down to check out the Escort again (which is now idling and revving like a motorbike) and spoke to my mate who's an SR20 tragic and showed him those flow numbers. He said if that is the case then yeah the small port flow figures definitely look choked on the inlet side relative to the exhaust. His suggestion since I already have a spare head was to take my good small port head off and get it flowed to get my own data. If the inlets are in fact the same as the exhaust and the numbers match that sheet, then he thought we could just bring out the small port to get it to flow the same ratio to exhaust as the large port head does. Not necessarily match large port flows but just get the inlet:exhaust flows making more sense. Then at least I'm left with a head that I know the history of too and is low kay.
So if the whole super high EGT thing is really a function of restrictive exhaust manifolds and tiny turbos being pushed way too far out of their efficiency ranges, then hopefully it'll be a sweet thing with the better TFSI exhaust runners and a freer inlet. Even if it made just makes a conservative increase in grunt with the Golf 6 turbo but does it on a chunk less boost I'd be very happy.
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