How high can you rev a stock 12a before it blows up?
04-14-03, 04:23 PM
#1
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How high can you rev a stock 12a before it blows up?
I know it will do at least 10,500 in 1st and 9500 in 2nd gear, is that really close to the point where the engine just grenades? lol And yes, revving that high does dramatically improve your quarter mile times, and there is still lots of power up there... i'm just wondering when its gonna let go, lol. (perfect opportunity for a rebuild with bridgeporting 
)
and if it does blow and i have to rebuild it, what are the best things to do to help the engine cope with ultra high RPMs?
)and if it does blow and i have to rebuild it, what are the best things to do to help the engine cope with ultra high RPMs?
04-14-03, 04:26 PM
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reccomended not exceeding 8500rpm... 9k is pushing it, and 10.5k is just RETARDED on a stock engine... The E-shaft will flex and bottom a rotor out on a housing, destroying the housing, rotor, and all seals.
On a stock engine, peak HP is at 7500rpm or so I believe, so there's no point in revving past 8500...
When you rebuild (notice I didn't say if), hardened stationary gears, carbon apex seals, clearancing rotors, etc, are all good measures to make a high-revving engine (peripheral port or bridgeport)
On a stock engine, peak HP is at 7500rpm or so I believe, so there's no point in revving past 8500...
When you rebuild (notice I didn't say if), hardened stationary gears, carbon apex seals, clearancing rotors, etc, are all good measures to make a high-revving engine (peripheral port or bridgeport)
04-14-03, 04:39 PM
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Yea my advice is if your gonna build the motor build it now with the hardened gears so you save the housing s rotors and seals.
Otherwise when it does let go it will be a bunch of worthless parts.
Otherwise when it does let go it will be a bunch of worthless parts.
04-14-03, 05:03 PM
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perhaps I shouldnt have said rebuild, I should have said swap in another motor and bridgeport that, and it probobly woudnt even go in this thing, the car is so badly rusted out I'm not even sure if theres a point to keeping it.
04-14-03, 05:21 PM
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Well don't blow the engine or rev it past 8000rpm unless you want to make it unusable, take it out and put it into a car that isn't rusty? If you want to have the novality of high reving, do as mentioned above, hardened stationaries, carbon seals. And if you want power up there, bridgeport, j-ports, perpheral it. Just don't intentionally break the engine, 1st gen 12a people on this furum have a high demand for used good rotor housings especially... should you choose to part out the car. Most would take offence to breaking good parts intentionally.
04-15-03, 01:54 AM
#6
Do you want the short or the long answer?
Short answer: punching the engine probably wont' blow it on any given day.
Long answer: This will, however, significantly reduce the life of your engine. If you are wondering how I know this, just ask man
Short answer: punching the engine probably wont' blow it on any given day.
Long answer: This will, however, significantly reduce the life of your engine. If you are wondering how I know this, just ask man
04-15-03, 02:16 AM
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Past 8500 your pushing it.Eccentric shaft flexes,and the Apex seals resonate(you see some fine nail marks onthe surface of the rotor housings)If you break a apex seal at that high rpms,then you can basiclly throw it away.
Why would you do that to a perfectley good engine?Its not even ported.....allready stopped at 7000....
Why would you do that to a perfectley good engine?Its not even ported.....allready stopped at 7000....
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04-15-03, 03:01 AM
#8
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sorry, its just gotten comical how many things are broken on this car. Maybe I will part it out sometime in the near future, she's about reached the end of the road 
04-15-03, 05:59 AM
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680rwhp12a, I assume you did more than just porting to make it safe for the engine to rev that high, even if the ports will mean it makes power up there. What internal mods have you done? Hardened Stationaries? Carbon seals?
04-15-03, 06:43 AM
#12
I read your email
My thoughts exactly browney. Sounds like a bit of misinformation to me. Just because an engine is ported and can make power up high doesn't make it safe to do so. Clearly it's the internal mods that make it safe, not the porting.
04-18-03, 10:04 AM
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I have a 81 12a with 70K original I took to a mechanic with Carb problems.... While I was standing next to the car I watched him bury the tach several times while the engine was cold in attemp to clear the clogged carb.... What kind of problems might this cause....... It seems to have devoloped uneven idle runs rough at speed and does seem to have allot more oil leaking near the dowel pins... What should I expect?
04-18-03, 10:20 AM
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Originally posted by hotrcknrll
I have a 81 12a with 70K original I took to a mechanic with Carb problems.... While I was standing next to the car I watched him bury the tach several times while the engine was cold in attemp to clear the clogged carb.... What kind of problems might this cause....... It seems to have devoloped uneven idle runs rough at speed and does seem to have allot more oil leaking near the dowel pins... What should I expect?
I have a 81 12a with 70K original I took to a mechanic with Carb problems.... While I was standing next to the car I watched him bury the tach several times while the engine was cold in attemp to clear the clogged carb.... What kind of problems might this cause....... It seems to have devoloped uneven idle runs rough at speed and does seem to have allot more oil leaking near the dowel pins... What should I expect?
04-18-03, 12:02 PM
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Originally posted by dingo
I'm not sure on the problem... but you should have smacked the mechanic for redlining it cold
I'm not sure on the problem... but you should have smacked the mechanic for redlining it cold
04-18-03, 05:35 PM
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Thats what I was afraid of..... Grrrrr... I am affraid that the life of the motor has been greatly reduced in ran as smooth as glass prior to that day.... I sat in it while it warmed up several times and it never skipped a beat now I fear it will die at idle form the missing.... It seems to fluctuate at speed as well... So sad it was a beauty... 2nd owner garaged since new with 52 K when I bought it now it has 74K with a motor thats ????? Shall I drive the remaining life out of the motor or is it more re buildable as it is?
04-18-03, 06:40 PM
#22
Re: How high can you rev a stock 12a before it blows up?
Originally posted by Raptor13x
I know it will do at least 10,500 in 1st and 9500 in 2nd gear, is that really close to the point where the engine just grenades? lol And yes, revving that high does dramatically improve your quarter mile times, and there is still lots of power up there... i'm just wondering when its gonna let go, lol. (perfect opportunity for a rebuild with bridgeporting)
and if it does blow and i have to rebuild it, what are the best things to do to help the engine cope with ultra high RPMs?
I know it will do at least 10,500 in 1st and 9500 in 2nd gear, is that really close to the point where the engine just grenades? lol And yes, revving that high does dramatically improve your quarter mile times, and there is still lots of power up there... i'm just wondering when its gonna let go, lol. (perfect opportunity for a rebuild with bridgeporting
)and if it does blow and i have to rebuild it, what are the best things to do to help the engine cope with ultra high RPMs?
04-18-03, 07:37 PM
#24
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Re: Re: How high can you rev a stock 12a before it blows up?
Originally posted by MIKE-P-28
if this is true then why do dyno sheets show a drop off above 6 k on a stock port?
if this is true then why do dyno sheets show a drop off above 6 k on a stock port?
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