bore and stroke options, intakes

[greyrabbit]

Was looking over Greg Raven's book.  He doesn't say much about diesels other than to mention that the rods etc. might provide gassers with some options, but he has lots to say about bore and stroke options for gassers.  There's lots of info on the tall block 1.9 l but has anybody tried stroker cranks or significant overbores for the 1.6 l diesel?

Also I couldn't help but notice the long runner intake manifold for the 16 valve gas engines.  It looks to be two part with the bulk of the runner in a long piece that crosses the head and a short curved piece that hooks under.  Does anybody know if it is even in the ballpark for adapting to the diesel?

Just sorta daydreaming but thought I'd ask.

[HarryMann]

Expect the ports won't match up, let alone the shenanigans with the rest of it but this fits, or should...

http://vwdiesel.net/phpBB/viewtopic.php?t=5258

Off the 1Y N/A engines I think

[Justin]

here is a good link on intake discussion
http://www.vwdiesel.net/phpBB/viewtopic.php?t=614&start=0

later
Justin

[HarryMann]

Seems there are a lot of assumptions there that an ideal NA intake manifold isn't much different from a turbo one... but is this really true and if so, why do VW make them so differently?

[greyrabbit]

Justin, thanks for the link on Jake's mod etc.  that's gets right at what I was wondering.  Still nobody mentioned a 16 valve intake I hope to get some measurements on one soon.  

Harry, I think you're right since the pressure in a boosted manifold essentiallyl changes temperature density, etc.  

What got me started on this was working on my NA car without the hood and doing a little seat of the pants testing.  Long hill, stop watch.  With no hood in the way cold air inlets were easy to rig.  To make a long story short nothing I rigged made any performance difference (at one point I removed the air filter and glued up a plexiglas scoop "sealed" to the aluminum plenum with tap ... a real kludge but if only had to last an hour!

Anyway it lead me to believe the problem must be in the stock intake manifold.  Perhaps the exhaust but that hard to buy..this think makes like 52 hp at 4500 rpm from 1.6l...doesn't take much of an exhaust to support that.

Anyway I don't really know I'm just fooling around which is the big reason I
like this little car so much.

Thank you both for your replies.

Bob

[HarryMann]

Ah! As long as you are getting air from the same temperature source, a scoop will make no difference till 120 mph, hen only about 1%, if we're thinking ram effect.

Pretty sure that reason long runner intakes aren't used on production turbos is that they don't make much if any difference, tuned inlets work by resonating + momentum effects. Looking back into the compressor outlet is not the same as looking back out into a plenum, so wave effects will not change sign ( a -ve wave will reflect back as -ve), not what you want. As for momentum effects, this so much less important when you have a strong +ve pressure gradient helping you anyway.

[saurkraut]

The sixteen valve intake will not bolt up.  It has very large, round ports, and the bolt holes are diagonal.  the spacing between the ports might even be different.   Trust me on this I have both IDIs and a sixteen valve gasser.  The Sixteen valve is really a different beast.  It has very little in common with the 8 valve gassers as well.

If you are a Tig welding wizzard, maybe you could cut off the fanges on the sixteen valve manifold and weld on the diesel flanges.

[greggearhead]

Pretty sure that reason long runner intakes aren't used on production turbos is that they don't make much if any difference, tuned inlets work by resonating + momentum effects. Looking back into the compressor outlet is not the same as looking back out into a plenum, so wave effects will not change sign ( a -ve wave will reflect back as -ve), not what you want. As for momentum effects, this so much less important when you have a strong +ve pressure gradient helping you anyway.

I am going to have to totally disagree with the statement that resonated tuning, runner length, etc chave little or no effect on a turbo (or super-) charged engine.  They have the exact same effect - physics don't change because there is a mechanical device pressurizing the intake instead of the atmosphere.  

The important point for manufacturers, is that the benefit it adds on a turbocharged engine is reduced (relatively speaking) because of the higher pressure differential.  Also, packaging and cost concerns on a forced induciton production engine can far outweigh the benefits of a slight increase in performance, when that same increase can be gotten by running a few more psi on the turbo, etc.  

Race engines designed for maximum power with a turbo use the same manifolding and design principles as a race NA engine.

[HarryMann]

Hehe Gregg, I stand corrected  

.. but being an awkward old sod, insist on a proviso or two, as I was playing a bit of  Devil's Advocate there to tease the facts of this out a bit more  :wink:

I itemised two different effects, wave tuning and gas slug momentum (often being referred to as inertia or the slug of gas effect).

The wave reflection I am pretty sure would be right messed up when it sees the impeller blades of a turbo compressor, rather than a plenum or the true open atmosphere at the ends of the intake pipes. So I now see that a plenum between the turbo and the intake runners is important to get that tuned length right by reflecting the sound wave with a reversed sign (becoming +ve after travelling up from and back to the intake valve), so 2 x runner lengths is the fundamental resonance at the sos at inlet gas temperature. And a decent sized plenum important.

The momentum or inertia effect in a long column, initially delays then reinforces the charging towards valve closure, but probably a lot less important when there is a good degree of forced induction.

However, traditionally and particularly with race engines, to capitalise fully on these methods of improving cylinder filling, considerable timing overlap is employed, as well as this working in harmony with a tuned exhaust, making a happy threesome at some chosen revband or other.

Supercharged valve timing being conservative, with less overlap, as well as production turbo exhausts being about as untuned as they could be makes me wonder if without all three, there might not be a kernel of truth in what I am saying?

Which is that without accurate before and after testing, it is difficult to know if there is much in it, or worse, a downside.

[theman53]

some old guys talking about intakes. I think I have proved this in my build. I am just bumping this for the masses to read for fun. Mainly Gizmo as he maybe making another intake soon, if he can't get his to work out with the IC.

[Gizmoman]

some old guys talking about intakes. I think I have proved this in my build. I am just bumping this for the masses to read for fun. Mainly Gizmo as he maybe making another intake soon, if he can't get his to work out with the IC.

Thanks theman - duly noted
With the amount of space I have on the intake side in the vanagon bay and a 50* engine, it would take some very tight elbows to make runners of any decent length.  Besides, the turbo is directly under it and going over the top is out as I can barely shut the lid as it is. I may have an inch or so but taking the valve cover off would be a major PITA as well.

If I can get the EGT's to drop below 1100, I'll get used to the lack of low end grunt. During my short test drive yesterday, we stopped at a friend place on our way out of town. There's a sharp right to a steep grade which I tried to twist through in second gear - no luck - I immediately had to shift to 1st. It was absolutely gutless for about 20 feet and then bam, on came the boost and up we went!.
It's not that bad - just a few seconds. One thing I can say about my wacky IC, zero lag.
I'll change out the water fittings next. Hopefully that will keep it cooler.

My guess is that the four 1/8" NPT fittings (2 in, 2 out) hold the water in there too long for the cooler to get the temps back down.

[CRSMP5]

i still gotta let lucas borrow my copies.. you go tth eoriginal one or th ereprint? i has both.. original IMO better.. the updated one lost some old pics.. but also gave a few new old pics too..

im waiting to see how landspeed guy does with his 2.0... that book has some really nice 1.8 16v shots.. including why the 1.8 16v versions has a weak spot in the piston.. that the 2.0 lacks..

anyone into engines o rcars.. buy either one.. buy both.. there is great info in it.. easy to find and lotso fdetail on the math..

[Jetmugg]

I'm keeping my eyes open for the right deal on the right set of forged pistons for the 2.0 application.

Steve.

[fatmobile]

 

has anybody tried stroker cranks or significant overbores for the 1.6 l diesel?
[quote/]

1st oversize 1.7TD pistons require an 80mm bore, 2.5 mill over the largest available oversize,.. and they work well with a 1.6 block/rods/crank.

 The block is called the KY block, european vanagons I think.
 I'd rather have standard size and leave a little more cylinder wall thickness but ended up with these.

 soo if you have a hydro block (a 1.6 head gasket won't fit over the pistons) that's bored to the max,.. these are a great option. I got mine for $100 more than new 1.6 TD pistons. $100 that I didn't have to spend on another block.
Great compression, sound and power.