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Downshifting at 80mph safe?

6074 Views 53 Replies 32 Participants Last post by  Frankiago
I've got a fairly stock '11 GSR. Cat back and test pipe are my only engine modifications. Just curious regarding how safe it is, with regards to my engine and transmission, to downshift from 5th gear at 80mph to 4th.

If I'm accelerating from 80mph to 120mph would I get there faster by down shifting to 4th gear from 5th or would I get to 120mph faster by not downshifting and leave it in 5th and accelerate from there?
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Downshift.
Okay, I guess it wasn't a stupid question lol
With manual cars, it's always more of a feeling and everyone drives with the tach! Just don't downshift and over rev your engine~
Never ever accelerate in 5th unless your going from 4th to 5th at high RPMS, far too many people have blown their engines by flooring it in 5th gear at low RPMS
Never ever accelerate in 5th unless your going from 4th to 5th at high RPMS, far too many people have blown their engines by flooring it in 5th gear at low RPMS
What I'm wondering about is what's the fastest safest way to get from 80 to 120. Are you saying it's unsafe to floor it in 5th gear at 80mph?
If you are just cruising at 80mph in 5th and just FLOOR it, you are putting a lot of load on the motor, which can make it blow.
Never ever accelerate in 5th unless your going from 4th to 5th at high RPMS, far too many people have blown their engines by flooring it in 5th gear at low RPMS
What do you define as high RPMs? 80 in 5th is approximately 3800 RPMs, so I doubt that's considered "high".
Aside from outrunning an explosion or Scout Troopers on Speeder Bikes, I don't see the point of this. But, I'd downshift. Fourth gear can easily take you to 100 where you can upshift again.
Would you guys say that accelerating from 60-80 mph with LIGHT throttle be a bad thing? And when i say light, i mean it takes a while to get up to 80 light lol. JW as sometimes your stuck behind someone slowly accelerating where you cant drop a gear and take off to 80mph.
If you are just cruising at 80mph in 5th and just FLOOR it, you are putting a lot of load on the motor, which can make it blow.
I had no idea. I drive at 80 daily...since it's something I do everyday you would think I would know exactly what my rpms are, but I don't remember. I want to say it's around 3600rpm on 91 octane in Missouri. My thought was one of two things:

-if you downshift to 4th you lose time in the shift and then you lose more time in the shift back to 5th as you are increasing speed to 120mph

or

-dropping it to 4th at 80mph will have the engine rpm to high which makes the downshift pointless


Never crossed my mind that if you floor it at 80mph I could damage the engine..never, ever..
What do you define as high RPMs? 80 in 5th is approximately 3800 RPMs, so I doubt that's considered "high".
I personally wouldn't floor it anytime in 5th unless I was already flooring it in 4th and then shifted up into 5th, I'm just being careful.

Would you guys say that accelerating from 60-80 mph with LIGHT throttle be a bad thing? And when i say light, i mean it takes a while to get up to 80 light lol. JW as sometimes your stuck behind someone slowly accelerating where you cant drop a gear and take off to 80mph.
Thats okay, light acceleration shouldn't be a problem, I'm talking about WOT.

Never crossed my mind that if you floor it at 80mph I could damage the engine..never, ever..
Lots of the guys who have blown up their engines on here was caused by accelerating in 5th. Be safe and downshift if your planning on going WOT to get to 120mph
Aside from outrunning an explosion or Scout Troopers on Speeder Bikes, I don't see the point of this. But, I'd downshift. Fourth gear can easily take you to 100 where you can upshift again.
I was personally thinking more along the lines of zombie apocalypse.
If you are just cruising at 80mph in 5th and just FLOOR it, you are putting a lot of load on the motor, which can make it blow.
I hear this all the time on these forums but it's always "too much load" or "a lot of load". How much load is too much load? Like if I were logging, what would be the most amount I would see before it blew up the (stock) motor?
too much "and's, if's, and but's" going on here.. just try it and report back
i wanna know why its considered to much of a load and a reason why it would blow. not because some guy had it happen to him. i don't see an issue for it. but its my first boosted car to play with so knowledge is always good. please explain why.
I hear this all the time on these forums but it's always "too much load" or "a lot of load". How much load is too much load? Like if I were logging, what would be the most amount I would see before it blew up the (stock) motor?
If your monitoring boost pressure I wouldn't go over 10psi at low RPMS.

too much "and's, if's, and but's" going on here.. just try it and report back with a blown engine
Fixed :)

i wanna know why its considered to much of a load and a reason why it would blow. not because some guy had it happen to him. i don't see an issue for it. but its my first boosted car to play with so knowledge is always good. please explain why.
There are plenty of posts on this forum that go into detail but the main reason is high gear at low RPM's = high load, this plus high boost = boom. Think about it, say your cruising in 5th at 2500RPM, you decide to go WOT, your hitting peak boost at low RPMS on your longest gear putting a huge stress on the engine, its just how it works.

You guys can do what you want, but don't say we didn't warn you...
i started to read up on the threads out of curiosity. some guys kinda explained. yeah its simple math and understandable.

im a diesel tech, like big rigs 18 wheelers, pulling what ever. so it just strikes me odd that this little engine cant take a little prolonged full boost. but a big rig would love that much boost/power as long as it didn't have to down shift climbing a hill. and i boost in 5th gear like every day just cruising down the interstate. driving style. two totally different worlds i know and way different realms when it comes to this stuff.

but i won't be doing it any more in my evo lol. i like my engine way too much to even risk it. good to know info though. thanks for posting it.
i started to read up on the threads out of curiosity. some guys kinda explained. yeah its simple math and understandable.

im a diesel tech, like big rigs 18 wheelers, pulling what ever. so it just strikes me odd that this little engine cant take a little prolonged full boost. but a big rig would love that much boost/power as long as it didn't have to down shift climbing a hill. and i boost in 5th gear like every day just cruising down the interstate. driving style. two totally different worlds i know and way different realms when it comes to this stuff.

but i won't be doing it any more in my evo lol. i like my engine way too much to even risk it. good to know info though. thanks for posting it.
I mean you can boost in 5th and to be honest most Evos probably could handle it but its just better to be on the safe side especially if your modded and if your anywhere above 350wtq, thats where you really get into problems. Running a stock or lightly modded Evo most likely won't be a problem but you never know when you put that kind of stress on the engine.
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