cygnusx1 Posted August 13, 2007 Share Posted August 13, 2007 Not sure if this has been posted but it looks insane. I have no info or background on this car other than what is posted here: http://www.tamparacing.com/forums/nissan-infiniti-tech/182897-baddest-l-series.html Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 13, 2007 Share Posted August 13, 2007 It has been posted and discussed before. I know you won't do this cygnusx1, but if someone starts talking about buying an OS Giken head for $10K or getting people started on a group buy or the typical BS misconceptions or confusion with the FIA or LY head comes up, I'll shut this mutha down! Quote Link to comment Share on other sites More sharing options...
olie05 Posted August 13, 2007 Share Posted August 13, 2007 They say it has a 9000rpm redline. Doesn't that contradict what everyone has experienced with L-series cranks? -or- is this problem cured by the overly priced kameari billet fully counterweighted crankshaft? Quote Link to comment Share on other sites More sharing options...
e_racer1999 Posted August 13, 2007 Share Posted August 13, 2007 anyone for a group buy????? i kid, i kid Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 13, 2007 Share Posted August 13, 2007 They say it has a 9000rpm redline. Doesn't that contradict what everyone has experienced with L-series cranks? -or- is this problem cured by the overly priced kameari billet fully counterweighted crankshaft? "Everyone"? Our L28 in the Bonneville Car runs at 8500. The L20A currently in the vehicle for G/PRO Competiton is shifted at 93-9500 rpms. And these are 'conservative endurance' builds believe it or not! In Japan, in the mid 80's, a 9K L-Engine was what you wanted if you were up front of the competitors. Non-Crossflow Carburetted Blowthrough (50mm Mikuinis) running twin turbos were routinely street driven with 400+Kw. I personally witnessed several passes at a local dyno in Okinawa in 1986 where the car consistently put down 444Kw! This was on the non-crossflow head, and having a redoline/shiftopoint (like that Japanese Accent there?) of between 9 and 9200 rpms. The crank harmonic discussed online is more related to the early cranks that were not properly counterweighted. Oh, and both the cranks in the Bonneville Car: Pulled out of the junkyard, polished journals, magnafluxed, and bobweight balanced. No polishing of the counterweights, no knife-edging, no cryotreating. Just a standard prep and good balance on a 163,000 miles L28 Crank. Same goes for the L20A Crank: only it had about 105,000 Km on it. Standard timing chain set, nothing fancy there either! "The 7500 Harmonic" is overblown and terribly misunderstood. And I'll agree with mortensen on the degradation of the thread---too much bad info bubbles forth far too easily on this topic, the referenced link is a good example of the swarf that gets thrown about regarding it. Are all the "Tool Shed" posts blocked from being 'searched' from the general search engine? Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted August 13, 2007 Author Share Posted August 13, 2007 Oh let me state this! The OS Giken head was HOT many years ago. Today we have new technology that supercedes the need to spend $$$$$ on an OS Giken head. In summary, don't waste your money on one of these heads (or even worry about the minor horsepower gains it may provide) Instead, use the ridiculous money they would cost, to build a powerful engine instead. Having said that, I never saw it used on a TT setup before, which is the reason I posted the photo I found. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted August 13, 2007 Author Share Posted August 13, 2007 Uh oh, I hear keys jingling...... Quote Link to comment Share on other sites More sharing options...
e_racer1999 Posted August 13, 2007 Share Posted August 13, 2007 ya, that's definitely a killer lookin' set-up. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 13, 2007 Share Posted August 13, 2007 Having done what 99% of our members would do and run a junkyard motor with a cheap rebuild (read no balancing) and had the damper come apart, I would report that there is a harmonic issue that exists. I think a lot of it can be overcome by proper balancing of the rotating assy and running a "good" balancer. The destruction of balancers (even new ones) seems to be even more prevalent in stroker motors, along with loosening of flywheel bolts. I think the harmonic issue is real. I don't think it means that you hit 7600 rpm and your engine explodes, but I do think it is real. GT racers run the stock crank to 9000 rpm as well, but the engine's lifespan is measured in hours. I'd be surprised if Tony's engine was running 10's of thousands of miles between rebuilds. I would also think that one of the aftermarket fully counterweighted cranks from SCAT or Kameari would solve or lessen the harmonic issue. Quote Link to comment Share on other sites More sharing options...
HS30-H Posted August 13, 2007 Share Posted August 13, 2007 Looks like tamparacing.com forum member 'Laurentz' did use the HybridZ SEARCH function......... What's his HybridZ forum user name, and does he really look like Stewie from Family Guy? Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted August 13, 2007 Author Share Posted August 13, 2007 Looks like tamparacing.com forum member 'Laurentz' did use the HybridZ SEARCH function......... What's his HybridZ forum user name, and does he really look like Stewie from Family Guy? Huh? English Humor I bet...I usually get English Humor. In fact I love English humor. I don't get this though? Quote Link to comment Share on other sites More sharing options...
HS30-H Posted August 13, 2007 Share Posted August 13, 2007 Huh? English Humor I bet...I usually get English Humor. In fact I love English humor. I don't get this though? Don't get all paranoid on me, cygnusx1. Relax. My point is that the guy posting all this on the tamparacing.com forum is simply cutting and pasting stuff that originated on HybridZ threads. Hence the irony ( in my eyes at least ) of the tamparacing.com thread becoming a new thread for discussion on HybridZ............... Just the internet going round in circles within circles again...... That guy must have signed up as a member here ( I would have thought ) in order to find the information and pictures, and then post it all on the tamparacing.com forum thread as though he's an expert on the subject. Or am I just being overly cynical? Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted August 13, 2007 Author Share Posted August 13, 2007 Paranoid? I am not. I searched for that photo here at hybridz before I posted it. I didn't find any other threads with that photo...which doesn't mean it's not here somewhere. But now I get your joke. It's like a snake disappearing after it swallowed itself by the tail. Quote Link to comment Share on other sites More sharing options...
veritech-z Posted August 13, 2007 Share Posted August 13, 2007 that photo was posted in one of the old OS giken threads by HS30-H himself, if I recall correctly. I think it might even have been the same thread that Alan posted the turbo LY engine towards the end... Here's the thread, looks like Alan emailed it to speeder, who then posted it up somewhere around page 2 or so... http://forums.hybridz.org/showthread.php?t=76847&highlight=os+giken *edit* I don't recognize either the username, or the car (might not be a "he" though, Lauren T and the Z to designate the car?). Definitely haven't seen too many Z's on white-stripe tires here in Tampa. I've always hated tamparacing and most of the people I see posting on there. I had a bunch of friends try and get me into it even back in my Honda days, and I hated it then too... Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted August 13, 2007 Author Share Posted August 13, 2007 Well that was 2003. This is 2007. J/K Sorry for the repost. I searched, I swear I did. Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 14, 2007 Share Posted August 14, 2007 Most of the discussion about 'the harmonic' revolves around crank breakage. It's not really a valid concern---like you noted proper balancer installation and running through a critical speed instead of loitering at it for extended period and you should not have a problem with crank breakage. Larger industrial engines experience crank breakage due to harmonics usually in the first critical speed. Cooper GMV 's were good for that, V16 with 3 foot bore, 6 foot stroke...if you operated under load or overloaded at the proper rpm, the result was not nice. That is the crux of the misunderstanding, like you stated JM, people think if you go over that rpm it goes 'boom' and that isn't the case. In fact, by limiting their upper engine rpm range AT the target harmonic you can exacerbate the issue! If you have access to proper vibration sensing equipment, you can ring the crank and see what it's resonant frequency occurs at, and work from there to lessen it's effects. The L28 ran for four seasons+ without incident. Upon teardonw nothing was amiss. The first season, while runnning a setup that had a power peak at 7500rpms, Andy did run across the harmonic dampner nut loose at the end of a run...literally fell out into his hand when he checked it! The damage was done, so he welded the nut to the crank and we ran it to the end of the season. We replaced the crank that offseason, and changed to the EFI setup with a power peak at 8250, and then started shifting around 8500 or so, and went three seasons without another incident related to the crankshaft...the piston pins walked and kissed the cylinder walls...but nothing on the crank. "Never seen pressed-in pins do that before!" Key to any harmonic is to pass through it as fast as possible to minimise the chance for resonance. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted August 14, 2007 Administrators Share Posted August 14, 2007 Key to any harmonic is to pass through it as fast as possible to minimise the chance for resonance. I prefer to pass through all RPM's as quickly as possible Quote Link to comment Share on other sites More sharing options...
blairjj Posted August 14, 2007 Share Posted August 14, 2007 My favorite part of the tamparacing thread... "Problem with the OS Giken head is that the cast was made of wood, so over time it warped and cant be used anymore. " I literally fell out of my chair laughing. I shudder to think that this stuff "becomes" fact the more boards its posted on. I hear the keys jingling myself Just my $0.02 Jay Quote Link to comment Share on other sites More sharing options...
hughdogz Posted August 14, 2007 Share Posted August 14, 2007 My favorite part of the tamparacing thread... "Problem with the OS Giken head is that the cast was made of wood, so over time it warped and cant be used anymore. ".... I think what he meant to say was that the wood pattern warped (that was used to make the cavity in the sand for the casting). That does sound pretty funny though... [Ramble on:] I've worked with "the German guys" (that's what I call them anyway) who create wood patterns for sand castings over at a high-end pattern shop here in town. After WWII, they said they "went with the winners" and brought their technology over here. The stuff they do is amazing...really a black art and totally fascinating (at least to me). I've also worked with the investment casting industry...where they make the high-tech titanium castings. It is almost as big of a project to design the casting process (the gates, runners, cores, chills...account for shrinkage, flow, metallurgy, etc.) as the design of the casting itself. In fact, it's highly empirical...I think this is part of the reason why the "old timers" are still vital to the business even though we've had computational fluid dynamics mold flow technology for quite some time... Then you need all the fixtures to finish machine it, inspect it, tweak it, etc. I guess what I'm trying to say is that it would be great if someone could get the head into production again, but I think it would take more than just the pattern unfortunately. Blueprints would be the best...the rest can be reverse-engineered at a high price. hmm...sounds familiar... [Ramble off] This is going into a five gallon bucket in the tool shed now for sure! Quote Link to comment Share on other sites More sharing options...
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