Crank Scrapes for L Series...

[Challenger]

Anyone know where to find them, or better have first hand experience with them? I had seen them on ebay a while back but theyre not there anymore. Anyone else sell these? Im looking to put one on my turbo build (l28et) and would like to start to get prices to add into my budget. From what IVe read here and other places they are a good addition to a motor and worth the money. (ones on ebay were ~$70) Thanks

[katman]

We tried a crank scraper during our ITS L24 engine program and lost a hp or two. I know that flies in the face of all V8 experience, but on a real SAE engine dyno with real anal retentitive people doing the testing, that's what we measured. To do a crank scraper right you have to get within .050 or so of the crank, the scraper has to be stiff as hell so it doesn't bend, it has to be angled properly, and it has to be able to shed the oil that its scraping. Although we put a pretty fair amount of time in engineering the thing I think we didn't have enough vent in it to shed the oil (adding holes makes it weaker and just bend out of the way of the crank, so tough engineering problem there). For me, I would be very skeptical of anybody else's parts just because I know what it takes to really make that work on a Z block. Although some of these aftermarket scrapers look really good, I wouldn't bother. That is, unless you're racing at the front in ITS and need an extra hp within a very constraining set of rules. For the street, where there are no rules , there's more reliable ways to get more hp.

 

IMHO.

[fredtam]

No experience with them and you have likely run across these searching but:

 

http://www.crank-scrapers.com/prod01.html

 

Thread on said scrapers:

 

http://www.zcar.com/forums/read/4/1624793/page=1

[socal73HS30]

hmm, ill have to find out where he was going to buy it, but my friend found a guy who made a dual layered crank scraper. the first layer, a metal layer close to the crank to get the majority of the oil. but then also a teflon layer fit to the crank that would wear to fit the crank for a very close wipe.

 

dunno if the second layer is standard practice as far as scrapers go cause i've never bought one.

 

if you want me to find out the maker, ill ask him again for you.

[Challenger]

Well I thought they all had the layer of teflon... Im not sure if im going to use one seeing that not many people have posted any/good results from them. And its just extra money, for the same price I could turn up the boost a notch to get alot more power.

[socal73HS30]

i guess the idea is to remove oil weight from the crankshaft so that it isnt as cumbersome at high rpms. the same friend who told me about it said he put one on his race z back in the day, and saw some hp goin from it. now, i dont know much about the car that it was put on, or exactly how much hp was gained. all i really know is that he built the car for terry allen of terry allen datsun down here in san diego. and that the car was a 3.1 stroker with turbo blowing thru 3 mikunis. he said it was at 450 hp or something.

 

but seeing as i wasnt even born yet, all i can tell you is what he's told me. and he doesnt talk about it much.

 

but, long story short, they do work, but you probably wouldnt see a noticeable unless its a fully built race motor. in which case the extra cost for the scraper and windage tray wouldn't be a big deal. i asked him if it would be a worthwhile investment for my street motor, and he said i probably wouldnt even know it was there. and in a motor like his, everything is done, even polishing the inside of the block for better oil drainage.

[Tony D]

"That which is not whipping around in a fog near the crankshaft is available in the oil pan for lubricating the engine."

 

As obtuse as I will get in the argument for installation.

 

Argue horsepower all you want, but keeping oil in the sump (like polishing the internals surfaces of the engine block to aid oil drainback) doesn't necessarily make more horsepower. It's not all about making horsepower. Sometimes, it's about making the engine live...

[woldson]

How about knife edgeing the counter weights?

[Daeron]

"That which is not whipping around in a fog near the crankshaft is available in the oil pan for lubricating the engine."

 

Quote of the day, whatever the argument, I just like the way this sounds

[Kevin Johnson]

Hi,

 

I am working on designs for the RB26DETT and ran across this thread.

 

The design we use on the L series engines is also an OEM design on the Dodge Viper third gen engine (2003-2006). The clearance on the Dodge piece is about three mm. This is about the same clearance as found with the Dodge SRT4 OEM scraper. They have large clearances to avoid time consuming fitting issues. The oem Nissan SR20 scrapers in the girdle have about 1mm clearance.

 

The 2007 SCCA F Production National Champion car was running one of our Teflon scrapers inside the stock windage tray. The scraper is the same general design as on the L-series. That 1.6 liter engine picked up 6-7 hp over and above the stock windage tray (retained) which also has scraper openings in it. Ask Prather Racing. By the way, the basic Mazda tray design can be seen in the Studebaker Type R tray from the early-mid 1960s. The technology has been around a long time.

 

The general scraper design is considered sound engineering and is cited by GM in a modern patent as background information. The attachment method is used as oem by both Suzuki and BMW.

 

Nissan makes huge use of scraper technology in its modern engines. It just does not seem that way because the L-series is older. If you look at the massive re-engineering of the Toyota and BMW straight sixes of the same vintage then you will notice millions of dollars being spent to add more windage control.

 

Well designed scrapers return about 2% to 3% of the output of the engine. In a big block Mopar hemi putting out about 900 hp that is around 30 hp. That corresponds well with the reduction in 1/4 mile ETs. Some engines have a higher return.

 

Cosworth Engineering offers aftermarket scrapers for the Evo motors. If you look carefully at their literature, they lifted our advertising. That is quite a compliment, I think. Their basic design is in line with our L-series design.

 

Most racers like the extra hp but are really most concerned about allowing their engines to live longer. It was interesting to me that the SCCA Formula Ford banned scrapers in the Zetec engine which is being allowed as a replacement for the Kent based engines. Scrapers have been used in FF for decades so they might know something there.

 

Porsche Cup in the UK will not allow scrapers (same basic scraper design as the L-series) because while helping to protect the engine they give a modest power boost and everyone would be forced to get one. Nasa Porsche 944 series allows them (same basic design as the L-series) because they help stop the engines from failing. Porsche uses scrapers in the stock 924 and 944 pans, by the way. As does Mercedes in their diesel engine pans but their designs are closer to the scraper used in the floor of the Ford FE pan starting over 40 years ago.

 

Anyways, that is my experience after making them for hundreds of different engine designs. I think your statement could be re-paraphrased to yield "they are a way to make more reliable horsepower." It would be difficult to think of a technology that has more empirical evidence backing it up.

 

IMHO

 

Edit: I know that I am often an egotistical jerk -- as Norm mentions in the other thread. I take what I do very seriously and often react badly -- that's my nature and a character flaw.

 

On the FJ20 forum I got into an argument with the director of a F1 facility. Oh well.

 

 

 

We tried a crank scraper during our ITS L24 engine program and lost a hp or two. I know that flies in the face of all V8 experience, but on a real SAE engine dyno with real anal retentitive people doing the testing, that's what we measured. To do a crank scraper right you have to get within .050 or so of the crank, the scraper has to be stiff as hell so it doesn't bend, it has to be angled properly, and it has to be able to shed the oil that its scraping. Although we put a pretty fair amount of time in engineering the thing I think we didn't have enough vent in it to shed the oil (adding holes makes it weaker and just bend out of the way of the crank, so tough engineering problem there). For me, I would be very skeptical of anybody else's parts just because I know what it takes to really make that work on a Z block. Although some of these aftermarket scrapers look really good, I wouldn't bother. That is, unless you're racing at the front in ITS and need an extra hp within a very constraining set of rules. For the street, where there are no rules , there's more reliable ways to get more hp.

 

IMHO.

[Kevin Johnson]

How about knife edgeing the counter weights?

 

 

That does work well too. A tuning firm in Belgium has been campaigning Porsche 944s with heavily knife-edged cranks and scrapers for two or three years now. They do make a difference with them as well.

 

The basic issue is that a pressure differential is formed around the spinning rotating assembly. Windage is a highly complex set of phenomena in the technical sense of complex. Knife-edging helps the counterweights and throws to pass more cleanly but they do nothing to stop pumping transfer between cylinder bays which must move through the rotating assembly. On a straight six this pumping transfer is a nightmare.