From everything I have ever heard about this, people don't use the diesel pistons.
From everything I have ever heard about this, people don't use the diesel pistons.
isn't the early volvo turbo engines this premise in OEM form?
Keith Tanner wrote: I've never tried to find out how far ours will go, as we don't have E100 here :)
Make your own!
It's not all that hard to be a legal distiller of alcohol fuel.
Ask all of the local bars to dump the leftover drinks into a bucket, and there you go. 
Swank Force One wrote: Here's more tantalizing hints that i keep running across. http://www.speedhunters.com/2012/07/you-know-that-one-audi/article said: Power comes from a Frankenstein engine using a 2.5L inline five cylinder diesel block and a 20v head from an S2. The block, which costs next to nothing (around $100 US!),
...stopping reading there.
Diesel 5-cyl bottom ends go for way, way, way more than $100. And you throw away the rods and pistons anyway.
Keith Tanner wrote: Remember that revs put different loads on the rods than compression.
Yeah, the tension loads are a killer, and Diesel pistons weigh about fifty pounds each...
peter wrote: Keith alluded to the difference in stresses between revs and compression - Corky Bell's book on turbocharging does an excellent job of describing this. Changing direction very quickly is a bitch! One of the other things I'd think about is the oil pump - spinning it 33% faster must result in interesting behavior. (33% based off your 4500rpm + 1500rpm comment earlier, perhaps I misunderstood your goals).
Block is identical, i could use the F2 oil pump if it was a problem.
Knurled wrote:Swank Force One wrote: Here's more tantalizing hints that i keep running across. http://www.speedhunters.com/2012/07/you-know-that-one-audi/...stopping reading there. Diesel 5-cyl bottom ends go for way, way, way more than $100. And you throw away the rods and pistons anyway.article said: Power comes from a Frankenstein engine using a 2.5L inline five cylinder diesel block and a 20v head from an S2. The block, which costs next to nothing (around $100 US!),
Well he IS overseas, and yeah throwing the rods and pistons away pretty much guarantees a dead end for me if that's truly what all these guys are doing, since the block is certainly not the weak point of my particular motor.
The other example i found was the 1200hp awd Polo "Vampir." Looks like he's using a 1.9tdi block, but again with custom forged rods and pistons.
Pretty sure i can call this a dead end.
You've got the block already. You may have the crank. Just build with what Mazda already gave you.
Ha, don't you already have a hot Mazda engine to be working on? I admire your excitement but you may be over working yourself.
pres589 wrote: You've got the block already. You may have the crank. Just build with what Mazda already gave you. Ha, don't you already have a hot Mazda engine to be working on? I admire your excitement but you may be over working yourself.
This was a thought exercise for the Miata. Research mostly... This is what i do. I spent almost a year researching stuff for the Escort before turning a single wrench on it.
But if that KL is the "hot mazda engine" you refer to, i'll be working on that again later this summer.
Most diesels, at least HD ones, have a longer stroke also. This brings piston speed into the equation along with the compression and reciprocating weights.
What I'm curious about is the deck thickness of the F2 head and how much can be safely removed to bump compression & quench, who does a good forged piston for stock or slight overbores, and what should be done on the rotating assy to assist in revving.
pres589 wrote: What I'm curious about is the deck thickness of the F2 head and how much can be safely removed to bump compression & quench, who does a good forged piston for stock or slight overbores, and what should be done on the rotating assy to assist in revving.
Wiseco and CP do pistons with a range of compression ratios that decking the head isn't really necessary.
The revving thing is partially a rod/stroke ratio, as well as a head that doesn't breath worth a damn. The intake manifold isn't helping things, either. I'm reasonably sure i can get an F2 to rev to 7000-7500rpms.
Swank Force One wrote: Well he IS overseas, and yeah throwing the rods and pistons away pretty much guarantees a dead end for me if that's truly what all these guys are doing, since the block is certainly not the weak point of my particular motor.
Same for the Audis. IIRC the gasoline iron block is proven to either 1200 or 1800hp.
The issue is the additional stroke from the crank, and the Diesel five may have a taller deck height like the Eurovan 2.5 block. The 2.2 and under engines are 1.8 VWs in many ways and the 2.5 Eurovan block is like an ABA in many ways.
Basically, if you want more displacement from a five, you need to go to weird blocks since the bore can't be taken out much more (88mm bore centers!) and the stroke is deck height-limited.
In reply to Swank Force One:
I'm of a school of thought where I'd rather have a flat head and dished piston than a flat piston and a dished head. And I hear you on not breathing. I just don't think the factory block & crank are weak. When you get to those power levels, let me know what trans you're using. I'm thinking custom bell housing and a Mopar/AMC Torqflite.
iceracer wrote: Most diesels, at least HD ones, have a longer stroke also. This brings piston speed into the equation along with the compression and reciprocating weights.
The automotive based ones tend to use similar strokes as their gasoline brethren, so that shouldn't be an issue. They do tend to have smaller bores, I assume not just for the additional cylinder wall thickness possibility but also for flame propagation reasons.
Flame propagation is the ultimate bane of a Diesel. Over 4000-5000rpm or so the fuel can't burn fast enough.
pres589 wrote: In reply to Swank Force One: I'm of a school of thought where I'd rather have a flat head and dished piston than a flat piston and a dished head. And I hear you on not breathing. I just don't think the factory block & crank are weak. When you get to those power levels, let me know what trans you're using. I'm thinking custom bell housing and a Mopar/AMC Torqflite.
The block and crank are pretty much indestructible. I'd put the rods a close second. I'm thinking ARP fasteners, wiseco pistons, and you're looking at a 600whp capable bottom end.
I have plans to make it rev/breathe.
I'll be starting with a TII trans. When it blows then i'll re-evaluate.
Swank Force One wrote: In reply to Paul_VR6: Are stock 16v pistons anywhere near as strong as diesel pistons made to withstand 10 more points of compression? I'm talking boost here. I've had my fill of n/a motors for the moment and a single cam 12v mazda motor would be my last choice for n/a builds.
400whp+ has been done on stock 16v pistons. Maybe even this morning if we had strapped the car down better. Whoops. The track will test the rest out. Stock vw bottoms are stupid strong.
Paul_VR6 wrote: Stock vw bottoms are stupid strong.
The problem is that with forced induction, you can easily surpass the generally-accepted 80ft-lb per rod or so that stock 144mm VW rods can reliably handle. Fortunately, aftermarket rods are fairly cheap/plentiful.
Your limit applies to the cracked cap rods but I have seen over 100lbft/rod on the earlier ones hold up, same with the 156mm rods. There is a stock bottom dyno on a methanol fueled car making even more on the stock rods/arp bolts.
Some of the aftermarket rods are worse the. The early stock ones.
ransom wrote: I gather one of the "hot-ticket recipes" (of dubious quality, I'll give you) for BMW M20s is to use the 524td diesel crank, because it's forged, unlike the e or i engines. I don't recall the relative stroke or other impacts, but I gather it was favored for its strength, so there's one incredibly dubious and unverified piece of info indicating that a diesel crank is good for a gas performance application
This is similar to the M42/M44 Engines. Substitute the crank and rods from a four cylinder BMW Diesel and you can bump the displacement from 1.8/1.9 to 2.1
Paul_VR6 wrote: Your limit applies to the cracked cap rods but I have seen over 100lbft/rod on the earlier ones hold up, same with the 156mm rods.
I'm speaking here of the stock 5cyl rods which are standard construction rods. They may indeed be weaker than the 4cyl stuff, from what I understand, they're drilled through the center. They seem to be the same as early 1.8T rods, though, aside from the rod journal size.
I'm only personally experienced with the 136mm rods, which feel like they weigh 50% more despite being shorter.
Bumping from the dead. I think i figured out what was going on here. This was just mostly a way to get direct injection on an F2.
R2 block, F2 oil pump, F2 head. Use F2 pistons (preferably custom high compression) if the compression ratio using R2 assembly would give way too much compression (but won't know unless both heads are cc'd.), shoot for 11-12:1 compression ratio, run E85, turn up the boost until you lift the head off the block.
Seems relatively straightforward in my head, but who knows, in theory.
Worth mentioning that the old R2 is still being used today under the guise of the "MZR-CRD" or Skyactive Diesel. Relatively low compression ratio at 16.3:1.
It's... intriguing, at least.
ANCIENT THRED OMG
How are you going to control injection on a direct-injected F/R2? There's a timing aspect that a lot of aftermarket ECU's don't do, correct?
Knurled wrote: ANCIENT THRED OMG
Can't say i don't refrain from jumping to conclusions.
I think the same thing happened with my wideband thread.
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