Acceleration?

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spb2002
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Acceleration?

Post by spb2002 »

Morning! :D

I've heard talk that the RX-8 isn't great off the lights, or that it doesn't have great acceleration because of low torque. Is this just a case of poor acceleration from standing still I take it? I'm guessing once you get over the 4k revs mark it starts to fly?

If this is the case, is there anything that can be done to improve this,, or just accept it and enjoy the upper end?
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Re: Acceleration?

Post by Dr. FrankenRex »

Forced induction is how you 'solve' it.

The RX8 is a low torque engine, which compensates by revving very high. In 1st gear you can't get the revs up 'in to the power' very quickly due to simple physics.

Forced induction is usually applied to boost the lower and mid-range so this would help.

The other option, which would have VERY limited usability in any other scenario is to go balls-out with a really low final drive in the diff to boost acceleration at the expense of speed in most other gears. Great for a track car but less functional on the road (depending on which drive you went for. 5.1 is "just about" usable on the road, anything more would be kinda pointless unless you were drag racing.

All of the above options are expensive, though.

Another option is to improve the tyres but that wouldn't solve the major issue of the RX8 when it comes to launching.

EDIT: 4K RPM is child's play in the RX8 rev spectrum. You wanna be ~6K minimum really for power to take over from torque.
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spb2002 (Mon Aug 19, 2019 10:57 am)
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Re: Acceleration?

Post by spb2002 »

Dr. FrankenRex wrote:
Mon Aug 19, 2019 10:42 am
Forced induction is how you 'solve' it.

The RX8 is a low torque engine, which compensates by revving very high. In 1st gear you can't get the revs up 'in to the power' very quickly due to simple physics.

Forced induction is usually applied to boost the lower and mid-range so this would help.

The other option, which would have VERY limited usability in any other scenario is to go balls-out with a really low final drive in the diff to boost acceleration at the expense of speed in most other gears. Great for a track car but less functional on the road (depending on which drive you went for. 5.1 is "just about" usable on the road, anything more would be kinda pointless unless you were drag racing.

All of the above options are expensive, though.

Another option is to improve the tyres but that wouldn't solve the major issue of the RX8 when it comes to launching.

EDIT: 4K RPM is child's play in the RX8 rev spectrum. You wanna be ~6K minimum really for power to take over from torque.

Thanks Doc! :D

So unless i'm actually racing, it is probably not worth the expense of forced induction, would you say?

I should mention that i'm coming in as a Newbie on this... My previous 'fast' cars were a Celica VVtli T-Sport, and a remapped Saab 9-3 2.0l Turbo. to me, these were relatively quick off the mark (the Celica less so - that kicked in at 6.5k revs too as I recall?)

I guess i'm trying to judge the RX-8 against these really.
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Re: Acceleration?

Post by PeteH »

It's really just a different way of driving. You can launch an RX8 quickly, but you need to get it to about 7000rpm, then slip the clutch as you leave the line. If you don't let the revs drop below about 5500rpm then the car will launch really quickly. If you get it right you'll be abusing your clutch. If you get it wrong you'll be spinning your tyres.

The real issue is that the gearing is really high on the 8 (as the Dr. says), so first gear does over 40mph. This does mean that if you hold onto first gear right up to the red line then almost all other cars will have had to do a gear change. And when they do you've got them... :twisted:
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spb2002 (Mon Aug 19, 2019 11:58 am)
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Re: Acceleration?

Post by Rostyghost »

As PeteH said you really need to maintain mid 6k rev band to have a really good acceleration. I've done it a few times but never really "raced" anyone, so can't compare it to anything, but RX-8's acceleration isn't bad or slow. You just need to hit a right rev window.
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spb2002 (Mon Aug 19, 2019 12:01 pm)
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Re: Acceleration?

Post by spb2002 »

Cheers Rosty/ Pete!
Either way, it sounds like theres fun to be had! :D
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Re: Acceleration?

Post by Dr. FrankenRex »

spb2002 wrote:
Mon Aug 19, 2019 11:03 am
So unless i'm actually racing, it is probably not worth the expense of forced induction, would you say?
Not at all, FI is a great way to give yourself some more power and more usable power on the road (afterall, you spend more time in the mid-range on the road than up in the top end) - there's just quite a few considerations to take in to account on the reliability front as Renesis engines in their stock guise aren't too FI friendly.

Not to say it can't be done, as there's a fair few supercharged cars running about, but it's certainly something to enter with your eyes wide open compared to a piston car.
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spb2002 (Mon Aug 19, 2019 12:51 pm)
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Re: Acceleration?

Post by Eddie_r32 »

I think acceleration wise you will be more than happy coming compared to your past cars, I imagine the Saab would take off well buy would run out of puff as the turbo started to struggle where as the rx8 keeps pulling all the way to redline in every gear, they are also responsive so providing you are in right rev band it will take off, no turbo lag to worry about
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spb2002 (Mon Aug 19, 2019 1:32 pm)
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Re: Acceleration?

Post by spb2002 »

Cheers Eddie! I have to say I cant wait to get one! :D
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Re: Acceleration?

Post by Honkytonk »

I accept being outdragged by most hot hatches, as I'm probably having a lot more fun than they are, and if they're dragging me they probably have something to prove whereas... I don't.

My mantra with the 8 when it comes to practical speed is "lose out from the lights, catch up in the corners". I very rarely, if ever, have to brake.

And of course if you're doing a cross-country run there's plenty enough power to do the job when you're doing 'ahem' Motorway speeds. Drop a gear (or even two if you're feeling particularly daring) at whatever speed and it'll pull away nicely. Just be aware that the rev range is there to be used, and your hot hatch competitor (unless VTEC kicks in yo), is going to run out puff before you do if they try and match your gear changes.
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spb2002 (Mon Aug 19, 2019 2:18 pm)
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Re: Acceleration?

Post by Ranjan »

Just accept you are going to be beaten off the lights but delight in the knowledge that once the bends appear you are in a different league and nothing gets into a driver’s psyche more than being unable to shake off a car in the bendy sections.

Ranjan.
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spb2002 (Mon Aug 19, 2019 2:18 pm)
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Re: Acceleration?

Post by spb2002 »

Both good points actually.....!!
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Re: Acceleration?

Post by delta0 »

They are tricky to launch that’s all. Can’t really just dump the clutch it needs more revs a bit of slipping of the clutch to control any wheel spin. Obviously not great for the clutch. Once moving and the revs are up then the acceleration is very much there!
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Re: Acceleration?

Post by warpc0il »

I actually think it's quite fun that the 8 is just that wee bit slower off the line, and then accelerates hard, and then just keeps going....

Sometimes I like to do a quick short-shift, while no one is noticing and then sail past as 2nd gear takes you up to 70mph at the rev limit :ninja:

... and it's nice to know that you've got another 4 gears to play with.

This is also another way to "impress" passengers that think that they drive "a sports car", that and switching the speedo to kph when they're looking away, and taking fast curves, roundabout etc, without touching the brakes.

The last one being slightly less fun in my 8 with fabric seats than other members cars with "leather" watching their passengers trying not to slide out of the seat round corners :twisted:
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Re: Acceleration?

Post by MARKTHOMASBRAND »

Honkytonk wrote:
Mon Aug 19, 2019 2:09 pm
(unless VTEC kicks in yo)
How very dare you :lol:
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Re: Acceleration?

Post by mi60o0 »

warpc0il wrote:
Mon Aug 19, 2019 7:30 pm
I actually think it's quite fun that the 8 is just that wee bit slower off the line, and then accelerates hard, and then just keeps going....

Sometimes I like to do a quick short-shift, while no one is noticing and then sail past as 2nd gear takes you up to 70mph at the rev limit :ninja:

... and it's nice to know that you've got another 4 gears to play with.

This is also another way to "impress" passengers that think that they drive "a sports car", that and switching the speedo to kph when they're looking away, and taking fast curves, roundabout etc, without touching the brakes.

The last one being slightly less fun in my 8 with fabric seats than other members cars with "leather" watching their passengers trying not to slide out of the seat round corners :twisted:
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