Performance modifications for 2004 n/a MK3 Race Car

[silversprint]

I would have thought there would be a benifit in having the hard top fitted rather than being open. I'm sure my top speed was higher with the hard top. Just replace the rear glass with polycarb.

But as you said silversprint. There's a whole load of weight to be lost all over the car. Also if there is something than can't be removed (eg battery) try putting it as low as possible to reduce roll radius, and also concider moving weight from the rear to the front if needed to get a good weight balance.

I doubt you'll need to add any bracing if your fitting a full cage presuming it ties the front struts together well.

Was thinking (and someone else may be able to correct me on this) how about loosing the ABS and also fitting a non power steering rack. You'd loose weight and well as take power drain of the alternator. (Smaller alternator?)

You can gut the stock top and it will get about 30lbs with a poly rear window. It does help with aero but not much.

A full cage is nice it and you won't need any bracing.

I would keep the ABS. There is very little weight to be lost and it work great with R-compounds.

The Powersteering is also nice but it can be converted to a non-power with just removing the electrical pump and adding a breather. Only issue is not sure it the rack won't overheat.

I would lose as much weight as add ballast to the floor.

If you can change gears or transmission then the C60 with LSD will give the most improvement in laptimes next to major weigh lose.

[silversprint]

A fully stripped  spyder will be close to 850lkg if not under.

Problem is the weight is limited to 1000kg on the grid to keep Mk1 2 & 3's balanced on power to weight ratio, which means you can only loose about 25-50kg over standard depending on the driver. Also the restrictions on what you can modify are very tight, induction is free, exhaust & suspension mods very limited and everything else has to be standard. You can strip out what you want though to save weight. I think i would focus on saving weight at the back so you can add balast to the front as it has a 55% rear weight bias.

Anti roll bars are the only free suspension mod so I would definately get them sorted to stiffen things up, that should really reap some rewards.

Can't wait to see the Mk3's debut this year, I really think they will spank the Mk1 & 2's. Handling is leagues above the others and should be able to keep level on straight line speed too. Good luck Rowland!

1000kg?? Is that with driver??

A stock spyder in complete street trim is about 1000kg.

If springs can be changed to any rate it is much better to upgrade spring than to add huge swaybars.

My spyder is about 1000kg with driver but its not completely gutted, does't have a full cage, and it's a 2zz.

OEM LSD was an option on 2004+ cars. Check to see if yours has an LSD.

[loadswine]

All UK supplied 2s had LSD and 03 onwards have 6 speed boxes and additional bracing.

[silversprint]

All UK supplied 2s had LSD and 03 onwards have 6 speed boxes and additional bracing.

That means they are also slighly heavier. I think Toyota also beefed up the front firewall. The Euro 6-speed has a useless 6th gear for racing. It too tall and pretty much never be used on a track unless you want to save fuel during an enduro.  s:D s:D

[Rowland]

Guys, just so you are aware and you don't think I'm being ignorant I was rushed into hospital by ambulance on Sunday evening after collapsing at home shortly after making my last post.
I've just got home thankfully feeling a great deal better.
PM's in my inbox will be replied to this eve as will a detailed reply to this thread.

Thanks for your patience.

Rowland

  s:) s:)

[Ilogik]

Guys, just so you are aware and you don't think I'm being ignorant I was rushed into hospital by ambulance on Sunday evening after collapsing at home shortly after making my last post.
I've just got home thankfully feeling a great deal better.
PM's in my inbox will be replied to this eve as will a detailed reply to this thread.

Thanks for your patience.

Rowland

  s:) s:)

Bloody hell mate hope nothing serious? All cool now?

[ChrisGB]

Even if you are having a full cage, if you can get away with bracing, it is worth tying the rear suspension mount points together as this improves on limit progression a lot. Dropping the ABS can help with braking distances too from Stus experience.

Glad to know you are out of hospital. Sounds less than fun.

Chris

[Rowland]

I have a really nice light weight exhaust mate.

I would recommend the Kakimoto GT 1-OZ single exit system with pre cats removed unless you can totally replace the cat system section? The kakimoto is very light weight.

Suspension I have KYB New SR specials, really nice non adjustable shock. Tein springs to go with them maybe?

Lightweight exhaust seems to make perfect sense.
I have a Kakimoto exhaust on my broken MR-S Turbo, I wonder if that would be transferable somehow on to my n/a race car?
I'm pretty sure (although the mk3 regulations have been written and not yet released) removal of a catalytic convertor is permitted.
KYB dampers, hmm definitely worth a thought if they're available - Cheers!

Are you allowed stiffer suspension bushes? What about chassis bracing? Of course tyres will be significant. Can you run slicks or are you limited to road legal tyres? Toyo R888 could yield a big advantage.

Chris

Using the mk1 and mk2 regs as a guide, I believe stiffer suspension bushes are ok but aftermarket chassis bracing other than a pretty full on roll cage isn't.
Tyres as Mark points out are a control item, all competitors must use Toyo R888's which are purchased at a heavily discounted price.
Wheels are stock sizes only including width, offset etc.

IF you can change the manifold, you may want to look at the PPE setup as well. This will make more top end power than the Zero on an otherwise stock engine when combined with a free flowing exhaust, though you will get more mid range with the Zero setup. Check out the dyno on my MR2 Page (link in Sig).

Chris

Fairly certain that the manifold must remain stock so I think sadly that's a non starter...

  s:( s:(  

Best best advice is to try to get the car as light as possible and spend as little money on engine mods as possible. Without an aftermarket ECU you will not gain muc  if anything from exhaust mods or intake mods. A simple short ram intake is all I would do.

Remove soft top, keep the car open top to save weight. No hardtop (hardtop is 50lbs that you don't need)
Remove A/C to loose weight and free up some hp
Remove the whole exhaust system and run a titanium straight pipe, (if noise is not restricted)

Change the transmission to a C60 6-speed this will improve acceleration and top speed, this will make the car only slightly slower than a 2zz spyder and is probably the best bang for the money mod you can do. Don't forget to add LSD. Light weigt flywheels, race clutch. Poly engine mounts.

Gut the doors and remove glass= lose 50lbs/door

Remove everything inside the car. Remove heater core. Carbon fiber trunk lid and hood, Add a rear wing. Smaller battery.

For suspension if you are limited to fix struts then nothing beats custom valved Koni shocks with custom springs. Spring rates (6kg front, 10kg rear) to start.

Roll the crap out of the fender and run 225/15 front and 235/15 tires R888. If slicks are permitted then 13 or 14" wheels and tires.

A fully stripped  spyder will be close to 850lkg if not under.

Some useful advice there and a lot of what you've suggested I've done previously with my mk2 race car.
Hardtop is a debateable one.
Where do you stand on the aerodynamics /wind resistance VS weight debate on that one?
With the roll cage installed in theory the hard top won't offer increased chassis rigidity I'd imagine.
There is a minimum weight limit to keep things fair of 1000kg's including driver.

The series is pitched as affordbale motorsport so no aftermarket carbon, glass window removal, aftermarket wings, wider wheels etc etc.

What is the C60 Six speed gearbox you mention, is that aftermarket as my Roadster currently has the stock six speed box?

[Rowland]

Bloody hell mate hope nothing serious? All cool now?

Seemed serious at the time, the emergency doctor shook his head and said "Meningitis" and called an ambulance.
Thankfully it wasn't but I've had a pretty bleak 48 hours or so.
Lots of bed rest to follow.

  s:D s:D

[loadswine]

Glad to hear that you are okay now. The 2 is great, but being here to enjoy it is the most important bit, have a good rest over christmas matey and look after yourself.  s8) s8)

[silversprint]

Some useful advice there and a lot of what you've suggested I've done previously with my mk2 race car.
Hardtop is a debateable one.
Where do you stand on the aerodynamics /wind resistance VS weight debate on that one?
With the roll cage installed in theory the hard top won't offer increased chassis rigidity I'd imagine.
There is a minimum weight limit to keep things fair of 1000kg's including driver.

The series is pitched as affordbale motorsport so no aftermarket carbon, glass window removal, aftermarket wings, wider wheels etc etc.

What is the C60 Six speed gearbox you mention, is that aftermarket as my Roadster currently has the stock six speed box?

Hope you are feeling better.

The C60 is the transmission in the Lotus Elise, 2zz toyota celica, matrix etc. It has shorter gears and is practically bolt in for the spyder.

I don't know if 30lb hardtop will really be a problem. The aero benefit is not a factor in speeds lower than 100mph. Not being able to run a wing is a major drawback. Also the stock front wheels are narrow. Since you are limited to 1000kg you will probably not be able to fully gut the car anyway.

Are you limited to running stock sized wheels or tires as well? Can you run rear wheels from an 2000-2002 spyder. These where 15s,lighter, and the smaller diameter helps with acceleration.

[markiii]

elise uses a C64 not a C60

[silversprint]

elise uses a C64 not a C60

It the same tranny just a different gear ratio for 6th and linkage on the other side. Either one will work.

[aaronjb]

The C60 is the transmission in the Lotus Elise, 2zz toyota celica, matrix etc. It has shorter gears and is practically bolt in for the spyder.

J-Spec 6 speed would work, too as it also has shorter gears.  Heck, J-spec 5 speed has shorter gearing too, so perhaps Rowland could swap gearboxes between his two cars (I'm not sure you'd be using 6th, even with the shorter box, on track)

[markiii]

elise uses a C64 not a C60

It the same tranny just a different gear ratio for 6th and linkage on the other side. Either one will work.

if 6th is different it isn't teh same tranny

[markiii]

on uk tracks j-spec 5 speed with lsd if allowed would be my choice

[silversprint]

The J-spec 6-speed is just a US 5-speed with a 6-th gear added on. Gears 1-5 and the final drive are the same as the US spec 5-speed car. The J-spec 6-speed is geared better than the Euro 6-speed but still not low enough. Also  it maybe hard to source one. It is still geared higher than the Celica 6-speed. The difference is very noticeable in any gear above second. Having hit 140mph in 5th gear I dont see how adding another gear above that is going to be of any use.

However if you are limited to only using a transmission that came in the MR-S from the factory then the easiest option is a US spec 5-speed/LSD. Brand new from the dealer they are $1600 US.

J-spec 6speed
1st 3.166
2nd 1.904
3rd 1.392
4th 1.031
5th 0.815
6th 0.725
Reverse 3.250
Final Gear Ratio 4.312

US Spec Transmissions
00-05 Celica GT & MR2 Spyder - 5 speed - C56
1- 3.17
2- 1.90
3- 1.39
4- 1.03
5- 0.82
R- 3.25
Final Drive- 4.312


The Celica gear ratio- C60
Celica GTS
1- 3.166
2- 2.050
3- 1.481
4- 1.166
5- 0.916
6- 0.725
R- 3.250
Final Drive- 4.529

Elise
1st 3.12
2nd 2.05
3rd 1.48
4th 1.17
5th .92
6th .82
Final Drive 4.53

[markiii]

or get a cheap Jspec 5 speed and add an lsd

[Ilogik]

did you sell the mk3 mate?

[ChrisGB]

With a stock engine, I cannot see much point in having the 6 speeder. I believe it is heavier than the 5 speeder? Also, with the ludicrously high gearing of the stock box, you will spend very little time in 4th on most tracks. 6th would be pointless.

If custom clusters are allowed, or a diff change, then a short ratio 6 speed setup could help.

Chris

[Rowland]

J-Spec 6 speed would work, too as it also has shorter gears.  Heck, J-spec 5 speed has shorter gearing too, so perhaps Rowland could swap gearboxes between his two cars (I'm not sure you'd be using 6th, even with the shorter box, on track)

Good thinking but my broken MR-S turbo has a SMT box so that wouldn't work.
At least the six speed will be fairly fresh low milege, if I start getting whooped by those with UK 5 speed boxes I'll have to look into it further.

  s:) s:)  

did you sell the mk3 mate?

The MR-S?
No, it didn't get a bid at £3k start.
Gonna leave it on the drive until I'm after the new year now.

On the upside I sold my mk2 Race Car on Tuesday though!

  s:D s:D

[Team_Dandism]

My MR-S Jap spec 5 speed box with LSD is still up for grabs if you need it Rowland.

[markiii]

J-Spec 6 speed would work, too as it also has shorter gears.  Heck, J-spec 5 speed has shorter gearing too, so perhaps Rowland could swap gearboxes between his two cars (I'm not sure you'd be using 6th, even with the shorter box, on track)

Good thinking but my broken MR-S turbo has a SMT box so that wouldn't work.
At least the six speed will be fairly fresh low milege, if I start getting whooped by those with UK 5 speed boxes I'll have to look into it further.

  s:) s:)  

did you sell the mk3 mate?

SMT box is just a manual with teh hydraulic actuator where the cables mounts normally are, it'd not hard to convert at all



The MR-S?
No, it didn't get a bid at £3k start.
Gonna leave it on the drive until I'm after the new year now.

On the upside I sold my mk2 Race Car on Tuesday though!

  s:D s:D

[Rowland]

My MR-S Jap spec 5 speed box with LSD is still up for grabs if you need it Rowland.

Noted, cheers buddy!!!!


  s:D s:D

[silversprint]

I decided to read the 2008 rules. The rules were for the MKI and MKII but I'm assuming the 2009 rules regarding the MRS would be similar.

Pretty strict. Not much you can do to the car.

The engine will need an oil cooler and 1zz do suffer from oil starvation on track so a moroso pan or accusump.

If the 2009 rules are similar and don't allow removal of the stock exhaust manifold then I expect some MKIII to loose engines as the precats explode and get sucked into the engine under racing conditions. Those precats were never designed to be on a race car. I also don't expect much if any power gain to be made from an exhaust if the precats remain in place. Loosing the 20kg muffler is the best you can do.

The soft top needs to come out to install a cage. You will need to either cut off pieces of the top to install the hard to or make solid mounts. Solid mounts used with the hardtop have been known crack some of the bolt holes on the hard top so keep an eye on them

Suspension I would recommend Koni struts valved for springs 6kg front 8kg rear.

LSDs are not allowed so a 5-speed regular gearbox is the best option.

Brakes I would run Carbotech Xp10 pads front and rear. Remove the backing plates from behind the rotors. I have seen little benefit from SS brakes lines on a MKIII. Xp10 pads are pretty aggressive you may need to disable the ABS if it become intrusive. We have found the ABS to be different in various spyder so your maybe fine. If using SS lines the ABS will get in earlier and will probably need to be disabled.

I don't know what size wheels are in the rules. Hopefully 15s front and rear since a 225/45/15 rear tire will be faster than a 225/45/16 rear tire.