Increasing top speed and other mods

[RichMann]

Hi,

I have a Toyota Supra 3.0 SZ Manual (non-turbo) and was wondering how I could increase it's top speed?

I take it to ~6000rpm in 5th gear and that is maximum. What modification could I make to decrease the rpm rate at that speed?

Also as far as I'm aware no modifications have been made to my '93 Supra, so what could I change to get increased acceleration and/or performance?

Thanks for any information/ websites you can think of

Rich.

[supraturbo]

It's not really about decreasing RPM's but more about raising the power levels at those RPMs.

I mean you could either turbo the NA or you can squeeze the power out of the engine as it is.

If you want a bit more throttle response, start with breathing. A free-flow exhaust, and CAI would be basic starts.

Check out the guys over at

http://torontosupraclub.com

and

http://www.supraforums.com

[mkivsoopra]

Originally posted by RichMann
I take it to ~6000rpm in 5th gear and that is maximum. What modification could I make to decrease the rpm rate at that speed?

To decrease the rpm at the same speed, you'll need to change the gearing. The NA 5spd will run out of breath shortly before it runs out of gear, so you're a bit out of luck. You'll need to change the rear end and increase HP to go faster. You have a 4.27 rear end ratio. Other options would be the 98NA's 4.08, TT auto's 3.76, or TT 6spd's 3.133. The swap is not exactly bolt on, but pretty close. As for power, options are endless if you go the turbo route

[repinS]

Originally posted by mkivsoopra
You'll need to change the rear end and increase HP to go faster.

Yep. Just changing the rear end to a taller ratio will give you the theoretical top end, but what you actually get may be lower than what you started off with because your can runs out of breath sooner

[RichMann]

Hey, thanks for the response

A free-flow exhaust, and CAI would be basic starts.

This sounds like the best place to start, I'll check out the Supra forums, thanks

Could you just clarify for me, when you say 'change the rear end' what exactly do you mean? the spoiler, part of the body kit, some part of the rear underside of the car?

Also what's the difference between a 'normal' exhaust and a 'free-flowing' one? is it simply size?

sorry, I'm fairly new to all this

thanks again

[Jeeves]

I'm not sure what scares me more, the fact that you think "changing the rear end" could mean the spoiler, or that you feel the need to increase the top speed of an already quick car.

The rear end, he's talking about the little metal box under the back end of the car. It has two shafts going out of it to the tires. There is also a gear in this box. Changing it out to a different ratio will give you a higher top speed.

'normal' -vs- 'free-flowing': Size, yes. Also your stock exhaust has two catalytic converters that are filled with a material. This limits airflow. So replacing them with empty pipes, and getting an overall larger exhaust system can help.

You'll need to change the rear end and increase HP to go faster.

This is very true as well. Aerodynamic aspect factor into top speed. In order to go faster you must overcome aerodynamics placed on the car. Thus you need to make more power to overcome a stock top speed as well.

Lastly, depending on where your car IS in the world, some do have top speed limiters which you will need to remove electronically.

[RichMann]

Originally posted by Jeeves I'm not sure what scares me more, the fact that you think "changing the rear end" could mean the spoiler, or that you feel the need to increase the top speed of an already quick car.

We all have to start somewhere

I'm just trying to get the best possible performance from my vehicle, surely you understand that

Many thanks for the information

p.s. how would a turbo conversion increase top speed? there is a maximum rpm rate in the highest gear, surely turbo would not make the car able to cross that maximum?

[repinS]

The addition of a turbo will NOT increase your top speed if you can already get to 6000rpm in 5th gear.

It'll only change how fast you get there.

You'll still be doing the same speed @ 6000rpm in 5th.

[RichMann]

Originally posted by repinS
The addition of a turbo will NOT increase your top speed if you can already get to 6000rpm in 5th gear.

It'll only change how fast you get there.

You'll still be doing the same speed @ 6000rpm in 5th.

Thought so

For anyone in the UK, I recently came across this site:

http://www.tdi-plc.com/

http://www.tdi-plc.com/toyotaSupra_home.html

Looks to offer a professional service, maybe I'll give them a try