:::RHMT::: Real Home Made Turbo
General Category => Engine Management => Topic started by: SirDragsAlot on April 01, 2009, 10:00:01 PM
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just wondering, is it safe to assume that every fuel injected computer system has a built in rev limiter? in theory we should be able to hold the gas to the floor and the rev limiter should stop us from blowing the engine up, right? for example i have been told that the yamaha motor that ford used in the sho taurus can rev to 10000 rpm with mods, is this a myth?
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gm v6's never make it to the rev limiter.
any motor can rev to any rpm, can the motor actually make it there though?
TRUTH O0
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If a car doesn't have a tach, it probably wasn't meant to be revved up high.
I would assume that every car that was manufactured would have some sort of fuel cut-off for warranty purposes, otherwise morons would be blowing their shit up very frequently because they can't drive or shift.
I would think that as long as the hardware is strong enough to support the revs (bolts, valvetrain, and balancing), good AFR's, timing, and abequate oil pressure you can rev up much higher than stock.
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Why does it matter anyway? It's useless to rev a car higher than the fuel cutoff for most cars with bolt-ons. The Yamaha engine in the SHO is not the same Yamaha engine in the R6, lol. They can't all be revved to hell and back while still making power.
Edit: The original SHO V6 could spin pretty high, making 10,000 RPM possible I suppose... but pointless. Either way, to answer your original question, even that motor was electronically limited.
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New SHO w/ paddleshift, 360bhp, AWD coming out 2010: http://www.bringbackthesho.com/phpnuke/pressrelease.html (http://www.bringbackthesho.com/phpnuke/pressrelease.html) ::)
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I towed a mint 93 sho the other day, the drivebelt came off...
Cleanest taurus I have ever seen.. It was blue with grey leather..
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heat and flow rates negate the need to rev higher. if its not designed to rev higher, then it shouldnt.
Rotating mass also plays a very large roll.
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heat and flow rates negate the need to rev higher. if its not designed to rev higher, then it shouldnt.
Rotating mass also plays a very large roll.
Huge roll at that. Loads from reciprocating stuff skyrocket with RPMs
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heat and flow rates negate the need to rev higher. if its not designed to rev higher, then it shouldnt.
Rotating mass also plays a very large roll.
Huge roll at that. Loads from reciprocating stuff skyrocket with RPMs
Which is why it's always better (from a stress standpoint) to up the boost, not the RPMS ;)
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i always float the valves in my sohc
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heat and flow rates negate the need to rev higher. if its not designed to rev higher, then it shouldnt.
Rotating mass also plays a very large roll.
Huge roll at that. Loads from reciprocating stuff skyrocket with RPMs
Which is why it's always better (from a stress standpoint) to up the boost, not the RPMS ;)
but arent you producing more heat and power as well and also increasing the stress?
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heat and flow rates negate the need to rev higher. if its not designed to rev higher, then it shouldnt.
Rotating mass also plays a very large roll.
Huge roll at that. Loads from reciprocating stuff skyrocket with RPMs
Which is why it's always better (from a stress standpoint) to up the boost, not the RPMS ;)
Yeah, that's usually the case. For the most part anyways. I've run the numbers before, considering the smallest cross sectional area of a BP 1.8 connecting rod, the mass of the piston and rod, and and dada and you have to make about 350whp to put the same amount of compressive load on the rod as it sees when spinning 7k RPMs, the stock redline. But rods often fail below that power, not from exceeding the working stress, but from buckling.
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i spun my b16 stock head to 9k with no problems. But i wasnt using it as my rev limit to say i would still shift at 82-84 ish but that extra 800 rpm would stop me from shifting into 5th in the quarter. when spinning tire it would bounce of the 9k but with the light load id say its not a big problem
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Which is why it's always better (from a stress standpoint) to up the boost, not the RPMS ;)
True that!!!!! Its not as hard on the motor, In most cases.
i always float the valves in my sohc
sohc what? I use to take my a6 to 8K all the time :yes: I even miss shifted once or twice and took that shit to the moon. Never missed a beat. I ran it from 7500 in 3rd gear and went to take it into 4th, and with my sloppy linkage and me wide open throttle shifting I slamed it into 2nd. :o So you do the math and tell me how high I reved it.
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sohc what? I use to take my a6 to 8K all the time :yes: I even miss shifted once or twice and took that shit to the moon. Never missed a beat. I ran it from 7500 in 3rd gear and went to take it into 4th, and with my sloppy linkage and me wide open throttle shifting I slamed it into 2nd. :o So you do the math and tell me how high I reved it.
i'm guessing you've never driven a big block anything
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You mean like the 1964 bb 390ci ford truck I have?
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it was a joke, clearly not a good one
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rev limiters will not keep you safe from mechanical over rev.
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Subaru Justy had no revlimiter.
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If by lucked out you meant drove it off a cliff, sure.
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If by lucked out you meant drove it off a cliff, sure.
9.8 m/s/s is darn fast accleration
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Subaru Justy had no revlimiter.
thats because justys are awesome, and with the auto they are ALWAYS in the powerband!!! just ask highroller about our hill climb adventures :noel:
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my old dbl barrel carb accord would rev to 9,000rpm
I painted the valve cover red and put type r stickers on, when people said it wasnt a real type R I would sit them in it and rev it to 9000. People would beleave me after that
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Subaru Justy had no revlimiter.
thats because justys are awesome, and with the auto they are ALWAYS in the powerband!!! just ask highroller about our hill climb adventures :noel:
I doubt any Justy CVT lasted much longer than warranty. So, Chad had one when he was 19 and picked you up from elementary school in it?
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New SHO w/ paddleshift, 360bhp, AWD coming out 2010: http://www.bringbackthesho.com/phpnuke/pressrelease.html (http://www.bringbackthesho.com/phpnuke/pressrelease.html) ::)
I would so drive one the new taurus.
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Repacked 500 with a ecoboost motor not sure I would.
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Repacked 500 with a ecoboost motor not sure I would.
500's are nice. Ecoboost motor looks badass to me.
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Ecoboost motor in a Mustang :)
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Subaru Justy had no revlimiter.
thats because justys are awesome, and with the auto they are ALWAYS in the powerband!!! just ask highroller about our hill climb adventures :noel:
I doubt any Justy CVT lasted much longer than warranty. So, Chad had one when he was 19 and picked you up from elementary school in it?
drain the fluid out of a cvt justy and you can drive for a few hours before you have any issues appear
Right. That's why you only see manual trans models driving around anymore.
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butler was a booming town
No.
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I live in a fairly upscale area, Jon, there are no Subarus here earlier than ~94, and nothing lowrent like a Justy or SVX (checked the resale on those lately?).
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Funny, KBB doesn't list a price on SVX that breaks $4K. You must live in a very affluent area where old piece of shit automatic transmission Subarus are in high demand, for one to sell for $4-7K. Also, I'm not finding a Justy that breaks $1500. Your economy would have to be booming to sustain such a market. Any luck finding a job?
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what i woudnt give to find a mint suby justy, no rust and 5 speed. they rocked
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My 83 supra saw 8500 a few times ::)
No limiter, just kicked out cam followers.
Yes, every ECM will limit at some point, but if the engine has the capacity to reach it is another story
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if you blo a rear rotor in an rx7, it will rev to the moon.
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o
if you blo a rear rotor in an rx7, it will rev to the moon.
or till the ignition cannot keep up
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oif you blo a rear rotor in an rx7, it will rev to the moon.
or till the ignition cannot keep up
why cant it keep up? it will kep up just fine.
How to kill a Wankel Rotary (http://www.youtube.com/watch?v=kO3lSTO8uWg#lq-lq2-hq-vhq)
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That fucking thing sounds just like my 2stroke weed eater....lol
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Funny how that works. If they wanted it to actually run for a while it wouldnt have.
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It just shows that reving an engine in nuetral doesn't really hurt them at all. if they had left the radiator cap on it probably would have ran all day at 9k.
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yah, no load plus mucho revs != anything.
usually guys that go anything higher than stock or use a 3rd gen water pump switch to an electrical unit. its better over all as you dont get cavetation past 10k rpms.
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It just shows that reving an engine in nuetral doesn't really hurt them at all.
:?:
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It just shows that reving an engine in nuetral doesn't really hurt them at all.
You going to test that theory that on your shit? I wouldnt
I know when I was working R&D for HTG racing we'd twist crankshafts at the end of a dyno pull when the load releases at 8000+ RPM. Engine would be fine through the pull, but never run the same again till the crank was re-phazed.
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It just shows that reving an engine in nuetral doesn't really hurt them at all.
You going to test that theory that on your shit? I wouldnt
I know when I was working R&D for HTG racing we'd twist crankshafts at the end of a dyno pull when the load releases at 8000+ RPM. Engine would be fine through the pull, but never run the same again till the crank was re-phazed.
Going from high load to no load is not even close to the same as never having a load.
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It just shows that reving an engine in nuetral doesn't really hurt them at all.
You going to test that theory that on your shit? I wouldnt
I know when I was working R&D for HTG racing we'd twist crankshafts at the end of a dyno pull when the load releases at 8000+ RPM. Engine would be fine through the pull, but never run the same again till the crank was re-phazed.
Yeah I have more then a few times. I never blown up an engine bouncing it of the rev limiter. One time in eastern KY I had my kx125 save my life from falling off a cliff It was a steep trail on a cliff face it had just rained the trail had a switchback going up I bogged the bike down going up it tried to just step off but it was so slick I was sliding backwards toward the edge.
I still had the bike running so with my hand I shifted it into first and ran it wot with me standing beside it and it pulled me up the hill t the next shelf. It took about five minutes to. That was luck and skilz son. :noel: two strokes are awesome.
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It just shows that reving an engine in nuetral doesn't really hurt them at all.
You going to test that theory that on your shit? I wouldnt
I know when I was working R&D for HTG racing we'd twist crankshafts at the end of a dyno pull when the load releases at 8000+ RPM. Engine would be fine through the pull, but never run the same again till the crank was re-phazed.
Going from high load to no load is not even close to the same as never having a load.
Load was not released until after the ign was killed.
Many cars will live forever against the limiter. thats why its there. But to free rev an engine that has no limiting will self destruct provided it has adequate valve spring pressure to achieve such RPM (floating valves will act as a limiter)
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It just shows that reving an engine in nuetral doesn't really hurt them at all.
You going to test that theory that on your shit? I wouldnt
I know when I was working R&D for HTG racing we'd twist crankshafts at the end of a dyno pull when the load releases at 8000+ RPM. Engine would be fine through the pull, but never run the same again till the crank was re-phazed.
You can snap/stretch rods or tweak the crank when you suddenly shut the throttle, too. Thankfully that sort of thing only happens to poorly designed pieces of shit.
I've watched D16A6 live on the revlimiter for years. Literally. There was a mexican't who'd cruise the local strip with his CRX held against the limiter in first gear, that lasted for the year and a half it took him to wad the car up in a ditch.
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yes, poorly designed, due to the crank being modular in design to accomodate roller bearings. If the crank could be forged in one piece, I believe it would never fail like that. The only time we had that kind of failure was on the dyno, never at the track, well, unless we broke a drive belt and over-revved the piss out of it because the CDI boxes we used had the limiters removed.
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and 260-280 HP 2-stroke on one liter naturally aspirated is pretty decent
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400 whp/liter is the barrier that impresses me.