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| Aboatguy | Factory Opti at more than 6900 engine rpm | ||
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Senior Guru
 
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I went to my favorite test facility this morning and mashed the gas for a little while and check this out.....remember this is a OEM partsladi opti on my daily driven c4
Check out rpm 16.....pcm shows RPM 6375 at 6375 or above. Now rpm 16 is a different matter it will register proper rpm [IMG]http://i14.photobucket.com/albums/a342/aboatguy/6900.jpg[/IMG] The dtc is a code from last Thursday that I need to clear. So what's the highest RPM you've seen on your LT1? |
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Posted on: 2009/12/19 14:25
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| CasetheCorvetteman | Re: Factory Opti at more than 6900 engine rpm | ||
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Gday Mike, i hadnt reved mine that high, i did change the cutoff RPM settings at one stage and wound the tacho til it was pointing at the right hand indicator arrow, DataMaster called it just over 6,500rpm, and it was still pulling quite well.
I set it back to the way i had it after that, the way i drove it i didnt need to rev it that hard!! |
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Posted on: 2009/12/20 0:43
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| Aboatguy | Re: Factory Opti at more than 6900 engine rpm | ||
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I don't need to rev it that hard either....but lifes too short to drive a slow car..... Find your AMG yet??? |
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Posted on: 2009/12/20 2:20
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| Andrew | Re: Factory Opti at more than 6900 engine rpm | ||
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2013 Memorial Day Car Show Winner!
 
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I would not rev a stock LT1 anywhere near that rpm for fear of floating the valves, running lean due to low # injectors, and I don't know how well the bottom end would handle that if done often. Have you modified the motor???
Also, I'd like to see the power curve at that RPM. You might run on the track slower, revving that high, than shifting at the optimal time. All of this is just my opinion. |
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Posted on: 2009/12/20 3:51
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2003 Atomic Orange Z06 Sold - 1996 Competition Yellow LT4 - DRM 383, NX N2O, Line Lock, LT Headers, 3" stainless exhaust, Power Effects, and many more mods SOLD 1996 Competition Yellow LT4 SOLD 1979 4 Speed with 383 |
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| CasetheCorvetteman | Re: Factory Opti at more than 6900 engine rpm | ||
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Andrew, his engine is capable of taking it without an issue, its built pretty strong, as was mine. Far from stock.
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Not yet mate, i have really had time to look too hard, ive been doing all my electrical work in my new place so i can move in soon. Im not sure which one ill go for yet either, i do very much like the W211 E55s, i wouldnt bother going up to the E63 in the W211, but i have also looked at getting a brand new C63. All depends how much ill be able to get to buy one when the time comes and how much they cost then. |
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Posted on: 2009/12/20 8:37
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| Aboatguy | Re: Factory Opti at more than 6900 engine rpm | ||
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Engine is not stock... Thread is about bone stock OPTISPARK...seems like a lot of folks talk smack about how bad they are, however, my experience with them is totally different. That is a screenshot of a bone stock OEM OPTI at a high RPM. That opti is in a daily driven C4 and gets to see 6000 rpm or more every time its on the road. Mike |
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Posted on: 2009/12/20 14:04
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| LT4BUD | Re: Factory Opti at more than 6900 engine rpm | ||
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Far as I know the LT4 & LT1 opti's are identical....so 6300 is no big deal as far as the opti goes....limiter on LT4 is 6400 with 6300 redline On my modded LT4 I am using the stock opti with rev limiter at 6800...mine is not a track car but it has been up to 6700 or so quite a few times with no problem.. |
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Posted on: 2009/12/20 15:38
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| pr0zac | Re: Factory Opti at more than 6900 engine rpm | ||
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i heard you can rev a lt1 past 7000 you just can't adjust the fuel and spark maps. it follows whatever the last cell was.
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Posted on: 2009/12/20 17:46
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96 lt4. 357ci, 11:1, LE 226/232, LE2 LT4 heads, ported LT4 intake, EM Gladiator44, EM LT's, stock exhaust, NX kit. |
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| Josh | Re: Factory Opti at more than 6900 engine rpm | ||
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The opti only ever sees cam RPM, not crank RPM, so it's not seeing anywhere near 7K. If it can't handle 3500 RPM's without falling apart, there's something wrong.
A 396 I was part of awhile back saw 7K nearly every day, and for 50+ pulls on the dyno with an MSD opti with no issues. If you take the MSD unit apart, the insides aren't of any greater build quality than an OE unit. The wheel is still wobbly as hell, and none of the other stuff appears to be a higher quality. I can't see it handling sustanined RPM better than a stocker, but who knows. |
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Posted on: 2009/12/21 1:16
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"Have ya paid your dues, Jack?" "Yessir, the check is in the mail." - Jack Burton |
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| CasetheCorvetteman | Re: Factory Opti at more than 6900 engine rpm | ||
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They are the same yes. Just go back and have another look at the pic in the first post. If you look at where it says RPM 16, youll see how many RPM it was really spinning at that point, and my eyes are seeing 6,972rpm. Quote:
Ive heard of quite alot of them failing above 6,500rpm. Lots and lots of them. I never knew why, cause i never saw one fail, apart from pics, which to me looked like the rotor could not take the centrifugal forces any more. Its spining nearly 60 times a second. It wasnt originally designed to be spun that fast. This thread is not about what you did with an MSD Optispark, which most certainly IS of a much higher quality than the OEM unit. Its about the factory unit, which it seems thousands of people knock it for its "lack of reliability", although its very reliable. The piece you call a "wheel" is the "rotor". Even my 160,000 mile plus old factory original optispark wasnt "wobbly as hell", it has some play, but very little for the work it had done, and the MSD that went in its place had NO PLAY WHAT SO EVER. NONE. NOT ONE BIT. If yours did, you or someone else hadnt assembled it properly. I did open them both up before installing the new MSD, and i compared the two, the MSD was indeed of SUBSTANTIALLY better quality. If you couldnt see that, then maybe you got a Chinese knockoff. Its better in every respect. No question about it. Anyone that knows what they are looking at will see that fact as soon as they open the box. Having said all that, when i did replace my original unit, it was still in perfect working order, even after more than 160,000 miles. I do however expect that the MSD unit would outlast most of the rest of the engine. |
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Posted on: 2009/12/21 14:06
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| BrianCunningham | Re: Factory Opti at more than 6900 engine rpm | ||
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I'll have to scan my MSD when it's hooked up on my new engine, which will be more than capable of those RPMs, though they won't be needed with the supercharger.
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Posted on: 2009/12/21 14:37
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Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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| Josh | Re: Factory Opti at more than 6900 engine rpm | ||
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Could be, I don't know why they fail. I'm not super familiar with them though. Quote: This thread is not about what you did with an MSD Optispark, which most certainly IS of a much higher quality than the OEM unit. Its about the factory unit, which it seems thousands of people knock it for its "lack of reliability", although its very reliable. Just trying to interject a data point. I'm sorry that you feel that the information/opinions I've provided don't apply here. Maybe others will, maybe they won't. Either way, neither you nor anyone else is obligated to read or lend weight to my posts. Quote: The piece you call a "wheel" is the "rotor". Actually, the piece I called the wheel is the degree wheel, not the rotor. I've taken apart a handful of stock units, one MSD, and one dynaspark unit. The degree wheel wobbled in all of them. Quote: Even my 160,000 mile plus old factory original optispark wasnt "wobbly as hell", it has some play, but very little for the work it had done, and the MSD that went in its place had NO PLAY WHAT SO EVER. NONE. NOT ONE BIT. If yours did, you or someone else hadnt assembled it properly. Since we've established that I was talking about the degree wheel, and you are talking about the rotor, I don't think your comment above has any relevance to my statement. I find it hard to believe that you've ever taken apart an opti that the degree was solid in. The MSD opti I was referring to created a stumble at 5700 or so on the dyno. On disassembly, one of the rotor screws had fallen out, and the other was loose. After repairing that, the stumble was gone. I guess that could point to a poor assembly from MSD, and maybe that was the cause of the wobbly degree wheel in the MSD unit I took apart. In all the OE units I took apart, there was plastic casting flash all over the inside of the housing. The MSD was the same. The encoder for both units appeared identical, as does the degree wheel. The rotor is an MSD brand rotor, so one could consider that an upgrade. The shaft and bearing from both units appears to be identical as well. Quote: I did open them both up before installing the new MSD, and i compared the two, the MSD was indeed of SUBSTANTIALLY better quality. Although it probably doesn't belong in this thread, I was wondering if you could expound on this statement. Quote: If you couldnt see that, then maybe you got a Chinese knockoff. Its better in every respect. No question about it. Anyone that knows what they are looking at will see that fact as soon as they open the box. I don't know, I suppose it could have been Chinese. Is there a way to know for certain? On the Chinese Walbro fuel pumps for example, the lettering is laser etched on the Chinese pumps and stamped on the actual Walbro units. Is there a tell tale sign on the MSD units? However, to be honest I haven't heard of the MSD units being copied and released by an inferior company, but it's definitely possible. Have you ever heard of this instance? In retrospect, why don't you PM the answers to the MSD opti questions. That will help keep from mucking up the thread with non-pertinent discussion. Or, maybe you could post the answers here for others to see. That way, everyone's knowledge grows and the forum benefits from it. Either way, condescending tone aside, thanks for the information/discussion. |
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Posted on: 2009/12/21 17:20
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"Have ya paid your dues, Jack?" "Yessir, the check is in the mail." - Jack Burton |
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| Aboatguy | Re: Factory Opti at more than 6900 engine rpm | ||
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Senior Guru
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Your response is the exact purpose of this thread. Many folks denigrate the opti...however, GM thought it was good enough for 6400 rpm (they always put a fudge factor in too) and most OPTIs last tens of thousands of miles if not hundreds of thousands....not bad for a factory distributorQuote:
AFAIK every mechanical distrubutor on a 4 cycle internal combustion gasoline engine travels at Cam rpm....the point is folks talk doom and gloom and feed into the fix for a problem that doesn't exist. Hence my datalog at as close as I could get to 7K without hitting my fuel cutoff in D/3rd gear. |
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Posted on: 2009/12/21 19:28
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| Aboatguy | Re: Factory Opti at more than 6900 engine rpm | ||
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I'm interested in this too! Maybe some folks will post some datalogs off Delteq, MSD, Bailey's LTCC etc at HIGH RPM lets say above 6600rpm and post on how long they've lasted, problems ETC. |
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Posted on: 2009/12/21 19:34
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| CasetheCorvetteman | Re: Factory Opti at more than 6900 engine rpm | ||
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Josh, the MSD unit i pulled apart was perfectly well put together and nothing moved in any way it wasnt meant to. The factory original was very old and still worked fine, but there was play internally and yes there was play in the perforated disc. I wouldnt go so far as to say it was "wobbly" though, as it certainly wouldnt move on its own.
The distributor its self didnt have any markings on it to suggest where it was made that i can recall, but the box said MADE IN THE USA on a sticker with a representation of your country's flag. I doubt they meant they only made the box there!!  I was not suggesting that a Chinese knockoff be from another company, im suggesting it may be being made where the other MSD items are allready made in China. If the quality was really not that notably better than OEM, i cant help but wonder. The sensor and the perforated disc in the MSD i had were indeed slightly different. It also mensioned something about that somewhere in or on the box. Quote:
The reason i did pull this part up is cause the MSD unit is the unit said to handle the high RPM that the OEM unit will apparently not. Not saying its not an interesting piece of information and im sorry if you took it that way, cause it shows the MSD is a capable piece, but its also said by MSD to be able to take high RPM, where as the OEM unit is not. Quote: The piece you call a "wheel" is the "rotor". Quote:
My mistake. It wasnt all that firm in the OEM unit i had after all those miles either. Thought you meant rotor, sorry mate |
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Posted on: 2009/12/22 4:02
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| CactusJim | Re: Factory Opti at more than 6900 engine rpm | ||
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The thing that I've heard fails in the OEM Opti at high rpm , was the rotor/conductor tip. The brass (or what ever metal the OEM is made from)is held onto the plastic rotor with plastic posts that are melted down over the mounting holes in the metal like rivet heads. At high rpm, the torsional vibration is more than the plastic can handle. The plastic 'rivets' shatter, dropping the metal conductor off the rotor to be dragged around in the spinning assembly till the engine stops.
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Posted on: 2009/12/28 6:24
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