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Discussion Starter #1 (Edited)
This is my first post and I'm hoping you might point me in the right direction to find the answers I need. I'd like to determine if the IS300 is a good platform to use for the dual purpose of open lapping track events and some fair weather street driving (mostly to and from track events). I've tracked a '94 Supra TT (BPU, suspension/wheels) and '93 MR2T (GT turbo, susp/wheels) for several years at an advanced level, and would like to find a replacement for the Supra. I've used it for the trek to distant tracks like Road Atlanta, VIR, and Road America because of it's larger carrying capacity, and because it's quite competitive with the C5, Viper, and 911 guys with their lightly modded street cars that tend to run at the front at these events.

I was impressed with the basic nature and driving experience of the IS300 when we considered buying one for my wife's daily commute, but lack of a cavernous back seat and trunk and fwd led her to a Camry SE for a DD. I know I would need forced induction to increase power closer to the 400whp range that I suspect would be required to still hang with my track buds and to make it really entertaining on the street.

While 400 whp is no doubt quite achievable, I'm looking for insight from those experienced at tracking a higher powered IS300 as to whether they feel that the effort and cost of modifications to allow the car to be used in this way were excessive. I'm comparing this to the other cars mentioned above that in some cases needed little more than a boost controller, cooling mods, track brake pads, wheels/tires, and minor suspension upgrades.

I've never actually seen an IS300 out on the road course at any event I've done other than seeing Reg Reimer's 2JZ-GTE at Watkin's Glen running the One Lap series. I've spoken with the team that runs a couple in the Speed Touring series and know they have done extensive mods for their racing needs, but I'd only be interested if it could be a capable track car with a little boost and some basic track mods. I'd also be interested in seeing a link to dyno results from a car that has been specifically setup for closer to 400 whp with quick throttle response for autox and track days.

Thanks for reading, and I don't expect to get much feedback over X-mas. I'll be reading old threads to find info as well.

Happy Holidays,

Bruce
 

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bruce. w/ the IS300, all you need a power. granted, its a sedan still. I daily drive my car to work everyday along the 401 and take it to several track day events a year.

I picked this platform due to its all-around balance of sportyness, luxury, performance etc and that it's the only Toyota that combines it all.
 

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did I meet u at Mosport this year?
 

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Discussion Starter #4 (Edited)
I don't recall meeting anyone with an IS this year. I'll find and post a couple of pics of the cars and hopefully we can meet at the track. I'm at Mosport usually ~10 days a year, but a cottage purchase and renovation prevented it this year.

Do you have any idea what sort of lap times an IS with power and basic mods as you suggest could do at Mosport, and what would be required to get into the high 1:30's?

Bruce

Supra at Watkin's Glen

MR2 at Mosport with wife doing PCA HPDE

MR2 with aero mods at The Glen
 

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Discussion Starter #5 (Edited)
Is there an overview anywhere that briefly outlines the general mods to be considered when preparing an IS300 for lapping days and for adding more power through forced induction by those who have done it? In the Supra world for instance we know you can add a boost controller to increase boost to 17 psi on pump gas to achieve ~400 whp on the stock twins. That roughly takes you to the limit of the stock clutch, intercooler, rad and power steering cooler, and oem brakes with upgraded pads and fluids when used on the track aggressively. And that swapping in a single turbo, tubular exhaust manifold, and FMIC can cause engine bay heat and various cooling issues when pushed on the track beyond around 450 whp. I do see good discussions on very specific topics though that address mods that may or may not be necessary for my needs, and might still be trying to figure out if this platform has any potential for me next X-mas without a few pointers:bigSmile:

Bruce
 

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Nice cars!

This isn't exactly what you were looking for, but hopefully it will put you on the right track:

 

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I know a few guys track their turbo IS's on a regular basis and I'm sure they'll chime in after the holidays. bgwillyis300 comes to mind as an avid road course racer. Unfortunately there aren't many high-powered IS300's close to Mosport, so asking about say Watkins Glen or another US track's lap times will likely yield more information.
 

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The SPEED World Challenge IS300 with MOTON suspension can do 1m30 at MOSPORT.

That's w/ a cage, some engine tuning (2.8L destroked), aero and a most bada$$ suspension out there. And not to mention a balls-out driver!

I think boost will help around mosport. But a proper handling car will do the trick too. It's true this car is underpowered......but you can still gain huge improvements with some good damper work.
 

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Power will be the easy part for the IS300 platform given ~$5k. The 2JZ is well sorted and understood and with the right F/I kit, 400hp is definitely doable. Cooling should be better than the supra due to the dual frontal openings. Of course, this is more expensive than the supra to get 400hp.

You'll need to get the right tranny for the job though and that will be some $$$. The original W55 5spd is only good for low 300hp. A W58 5spd (~$500) from the NA supra will probably handle high 300s. You'll probably want no less than a getrag 6spd from the supra turbo for reliability of extended track sessions. Another $5-6k.

Brakes are descent but probably not enough for 400hp and stickier tires. Figure another $2k. I think the IS is a slightly lighter platform.

Suspension is another area where you'll want to invest $1-2k. Geometry is good due to the dual wishbone setup which is similar to the supras but probably more compliant.

A big limitation of the platform is the amount of tire you can stuff in there. You'll want as large of a front tire as you can squeeze in there due to the iron block 2jz and that will be the limiting factor for cornering traction as the chassis really needs a similarly sized F to R setup without too much stagger. Without fender flares, largest is probably a 245 - 255 with some rolling.

It's got all the right DNA but will take some work and money to get up the levels of performance you expect.
 
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Coilovers, transmission, chassis braces, brakes, and the widest tires you can fit that's really about it. Keep an eye on the front wheel bearings (the heat from braking really shortens the life on those).

I daily mine with regular track & drift events. It's really pretty easy to get it ready for track use.
 

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Discussion Starter #12
The SPEED World Challenge IS300 with MOTON suspension can do 1m30 at MOSPORT.
I had the pleasure of spending a day with Andrew W. from AAR in his STi DD and my MR2 around Mosport in '06. Both he and his father are among the nicest and most knowledgeable people you'll ever meet at a track. I don't think I should try to compare his race car setup and driver skill with my street set-up lapping aspirations!

TeCKis300, if you're trying to switch me to the IS-F Evo, I think it's working!
 

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Discussion Starter #13
Coilovers, transmission, chassis braces, brakes, and the widest tires you can fit that's really about it. Keep an eye on the front wheel bearings (the heat from braking really shortens the life on those).

I daily mine with regular track & drift events. It's really pretty easy to get it ready for track use.
How close to 400 whp is your experience based on, or are you referring to requirements at near stock power levels?
 

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I'm not currently at the 400hp level you're curious about.

However, I've been beating on this car from the 3rd day I owned it doing at least one auto-x a month, 6-8 track events a year and 2-3 drift events a year. That being said Teck is right on in his recommendations.

Chassis braces were very noticable in their help. The tires however are the key. The front fenders aren't very wide. :( With the 400hp range you can run wider rears. I have seen people fit 265-275 rears with the proper offset wheel under stock rolled fenders. Fender flares will allow you to fit more tire.

The only other thing that would concern me with more power would be to put in a stronger gearbox like the v160. The people that have swapped the rear have simply done it for gearing purposes. The factory LSD works fine until you are able to lift a rear tire through the turns. I've only done that on one turn here at LVMS and at autocrosses. Other tracks have been fine.

If you're halfway descent and running r-compound tires you will be able to kill the brakes.

One last thing, I'm not familiar with the track you're asking about or the one's you run on, but if they are high speed tracks you will want to trick the computer as you will be limited to 143mph.

Hope that helps.

I have been around Laguna Seca in an IS-F as well and out of the box it is very fast and capable. The IS300 is a track sleeper if setup properly. ;)
 

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Hey Bruce,

Hopefully we'll meet up at Mosport this year!

For your new car, I'll share my progress with my street/track IS300 and where I've ended up now.

I began modding the IS300, Moton suspension, Rotora brakes, full exhaust, hotchkis sways, Recaro seats, with plans of adding forced induction and a rear half cage.

What I found at this point was a car that was relatively quick (2:03 at Shannonville long track), and had a definite snap oversteer condition. This can be corrected for with the development we did for the racecar subframes and rear suspension (mainly correcting toe change at lower ride height), and should be done for anyone serious about driving an IS at the track fast.

However after some of my on track experiences during 07, I quickly realized how much I value having my Hans device on my shoulders, I'm quite sure it saved my life at Watkins Glen in our first World Challenge race this year, and although many of my fellow track drivers/racers tell me when they're driving their street cars on track they don't push 10/10ths, there is always the possibility of a suspension/brake component failing causing an uncontrolable off even at 7/10ths that could be quite serious. Because of this, installing a half cage that would allow use of harnesses and Hans device moved up my priority list.

I began to evaluate what I would be left with, a relatively large and heavy sedan with room for two passengers. All of the functionality of the IS300 as a daily would be gone with the install of the half cage, and I would have the practicality of a sports car, with the chassis stiffness and weight of a sedan. At this point it made much more sense to me to switch from the IS, to the S2000 I'm preparing now. I'll be building the half cage soon, and with it installed I will still have seating for 2, the lightness, and chassis stiffness of a sports car, plus the responsive steering, clutch feel, and one thing that frustrated me with the IS, a responsive throttle.

That said, when fully prepared our racecar IS300's have some of the quickest response of any touring car I've been in, the chassis does have great potential. I suspect 1:30 or better lap times would be achievable with 350whp, Moton clubsports, and the other usual performance upgrades. Our race IS300's were just dipping into the 1:30 mark this year with 227whp. We are currently revamping our engine program to get up to competitive hp for the 2008 season, as this was our shortfall during the 07 season.

I hope this helps with your decision, if you do decide to do the IS300, let me know, I have mine for sale :) haha, but seriously I'd be happy to help if you have any questions just let me know. [email protected]

Thanks!

Andrew
 

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Discussion Starter #16
Great to hear from you Andrew, and I'll look forward to seeing that S2k tearing up the track! Your change of plans make a lot of sense.

From what I've learned in this thread and others, I can see that what I'm trying to achieve will be an uphill battle. I've taken the Supra about as far as is practical for a street/track day car with respect to maintaining high reliability and cost vs. performance, and I found that some of the obstacles I face with the Supra exist with the IS300 also. I'll outline them to encourage general discussion, and relate them to my experience since it's engine and transmission seem to be sourced for the modded IS300.

The full weight Supra is relatively heavy at 3460 lbs, and removing the spare tire, tool kit, and floor mats probably doesn't help any more than it does with the IS300. The straight six is heavy and the resulting front weight bias puts enormous burden on the front tires. I run 285/30/18 R compounds on the front of the TT and they are the limiting factor for cornering speeds, overheating within 3 laps unless managed very carefully. It also doesn't help that front max. camber is limited to -1.5. I can understand the IS would be front tire challenged if limited to a 245.

I don't find the gearing with the Getrag 6 speed to be a good match to the 2Jz-GTE engine on the road course. 2nd gear seems too low and 3rd too high for slower corners, and the spacing between them a little too wide. 4th gear runs out early down a straight causing a shift to 5th that would likely not be necessary with a 5 speed tranny. A big part of the problem is that the 2JZ-GTE has a relatively narrow powerband, with mine having 300 ft-lbs available from just 3700-6500 rpm (with the twins spooling in true-twin mode as recommended for track durability). That's an effective powerband of only 2800 rpm, and it feels that narrow when chasing some of the faster cars.

Redline is fairly low at 6800-7000 rpm, but the optimum shift points are closer to 6500 because horsepower falls off above just 6000 rpm. The powerband could be improved dramatically with a small single GT turbo conversion, but the lack of a T3 exhaust manifold necessitates the use of a turbo fitted with a T4 turbine housing that shifts peak turbine efficiency too far up the rev range to provide a responsive throttle in the range you need it most on the road course. While the drag racers and big power guys love this drivetrain, I've never heard anyone accuse the singled GTE of having a strong or responsive low/midrange powerband. It seems T3 fitting isn't available for converting the stock IS 2JZ-GE engine either for those going that route.

Under hood and fluid temps are very hard to manage on the Supra at the 400 hp level on the track, particularly when a FMIC is placed in front of the radiator, and I suspect the IS would experience the same problems without modifying the front bumper/fascia and hood.

So while many of these issues can be handled with enough money and mods on a dedicated track car, I think they're going to be too challenging for my street/track day needs. I hope the discussion will continue to assist others meet their own particular needs.

Thanks again for all of your responses.

Bruce
 

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This is exactly why i have done what i have done. My previous go fast car was a Turbo Starlet. fwd 1300cc of fury. Handled great decent power then i made a manifold and slapped on a gt28r. It was great when you beat on it but a little bit too much for street. After it died in a hurricane i decided i wasnt going to do that again. I was going to buy a truck and if i found a decent car i would make it a project and a weekend warrior. No compromises, barely streetable that would tear up the dexterity type courses and evolve to a track going car. To me there are too many compromises to be made for daily driver and too many temptations when it gets fast.
 

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A better option for a well rounded daily/track IS is probably the route ISZach went. More solid NA power paired with a lighterweight setup. Since tire-size is a precious commodity on the IS chassis, you'll really want to focus on weight.

Are you asking for 400 crank or rwhp? Since you're from the supra world, I'll assume wheel hp. That's A LOT for the stock IS setup to handle which is why you would need to address almost everything I posted above.

From my experience swapping in the full 2JZ-GTE motor, I noticed a substantial weight gain on the front end, so much so that turn in was affected, and the nose seemed undersprung and floaty in turns. This was with medium rate Greddy coilovers. I had to upgrade to Hotchkis sways before my car got it's front end set and turn-in back.

An aftermarket turbo will prob save you a good 50+ vs the stock twins however.

The GT35R is an excellent T4 flange sized T3 turbo. It should buy you the powerband you're looking for from 3500 to 7200+ with an extended rev limiter.

Gearing will be a problem unless you address the rear end ratio as well if you decide to change from the stock tranny.
 

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Discussion Starter #19 (Edited)
I'd prefer a normally aspirated engine every time on the road course because of it's superior throttle response, and while shedding weight is a given, it's also pretty difficult to do in a serious way on a daily driver. So unless there's a nice lightweight 5L with a minimum of 400 hp ready to swap in I think we're going to have to stick with forced induction and make as much usable power as possible for the straight bits to make up for short-comings in the corners. I considered somewhere around 400 whp as likely being necessary in an IS300to continue to dice it up with my track buds, although I bet the car would be a lot of fun at any power level.

The GT35R is an excellent T4 flange sized T3 turbo. It should buy you the powerband you're looking for from 3500 to 7200+ with an extended rev limiter.

Gearing will be a problem unless you address the rear end ratio as well if you decide to change from the stock tranny.
I would build for a 4000 rpm wide powerband, and experience with the Supra drivetrain has shown that it needs to start as close to 3000 rpm as possible. A change of gearing could quite possibly change those two numbers slightly. Many tracks I've driven have corners, or a sequence of corners, that force rpms to 3000 rpm or below in 3rd gear. While it's possible to also take them in 2nd gear with peak power on tap, that is not always more beneficial to lap times. The problem comes back to the spacing between 2nd and 3rd gear, and the lack of engine power closer to 3000 rpm. The cars with stronger lower rpm power simply walk away from you exiting these corners, and since they frequently lead onto a main straight their exit speed advantage is multiplied all the way down the straight. Good examples of 3000 rpm 3rd gear corners would be Mosport's T5a, Road Atlanta's T7, and Virginia Int'ls "Oak Tree", all of which lead onto major straightaways, and all of which can't be improved upon by using 2nd gear in my experience. It really bites to work your way up all around the track to get on the tail of your prey just to have him leave you in his dust getting on to the straight...lap after lap. It's pretty bad when you have to rely on the charity of the track worker to "blue flag" the guy on the straight to let you pass because he opened up too much of a lead to catch on your own!

But building a setup that can reach full boost (say ~15 psi for example) and begin it's powerband ~3000 rpm is just one part of it. The other part is that it needs to be able to spool that early in order to optimize your throttle response at every rpm above that...which is basically all the time on the track. As you brake, corner and accelerate closer to the limits of adhesion a responsive throttle becomes much more important to balance or even steer the car.

So if you're going to go to all the trouble and expense of swapping an engine, transmission, and all the other mods required for the track, I think it makes sense to choose the best matched turbo for the application. I won't comment further about that in this thread because it's getting too off-topic, but would be happy to participate in a technical thread where we can crunch the numbers, plot some maps, and identify the match together. For now I'll just say that if you had two identical IS300's tuned to 400 whp for us to track together, one with a GT3582R T3 turbine housing with lowest AR, and one with the T4 housing, I'll take the T3... and give you a head start:)

I'm off for a weeks holidays and may have limited computer access. Happy boosting, and Happy New Year!

Bruce
 

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Well presented and I am really interested in the depth of your comments and experiences.

Regarding the T3/T4 turbo, I personally would go with a T3 turbine as my car is a street car first and not a dyno/hp queen. But I also have to be realistic as to what's available in the market and there simply is not much of one for a T3 sized manifold. Everyone that plays in the 2JZ market caters to the hp is king attitude.

Also, since you have to address the gearing question anyways...you can simply tune the motor to have a wider powerband up top and stretch the rev limit. While a T3 manifold might be ideal, you may want to simply settle for a powerband from 3500 - 7500 which is definitely doable for motor. A getrag with the stock rear end will make for short gearing already. The larger exhaust platform will also help with heat management for extended track sessions so it's not completely a lose lose situation.


And speaking about NA power...the Lexus 430 V8 has already proven to be a viable swap for the IS, and may indeed be lighter. Only tricky thing would be adapting the tranny but kits are available. Some traditional tricks to the head and flow mods should make for an easy 350+ rwhp.
 
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