Motors My Celica GT-Four Build Thread! - And Then There Were 4 (Update 25/08/20)

Good fast-road set coilies will be more than enough for light track work. A full-on track suspension is far too hard for public work, not to mention the expense of having track dampers serviced so often.

I often think that some folk go far too aggressive with their suspension on track cars. 3-way dampers etc is complete overkill for all but the most dedicated track day car, you need to be racing on a regular basis to get the setup right and get to know what settings you need to tweak from track to track and how far to take it. 99% of the time the extra cost of super dampers like that is better spent on driver tuition and a decent geometry setup.

That said, those Tein coilies look rather excellent, as long as you can find a good road setup then you're on for a winner.

 

I just posted the lmgtfy link for handiness, rather than posting a load of google links Yeah the pelt setup is looking really promising. The creative engineer part of my brain is going ten to the dozen with ideas for the pelt AC system! I'm such a liquid cooling nerd!

Oh yeah, the TEIN coilies are adjustable in every way possible - they are pretty much the pick of the bunch for a combination of track and road use, based on what I've read from people who have them on their own cars. Several members of the GT4OC and 6GC sites have installed them in trackday/weekend drive GT4's. I'll definitely be giving the car the usual prep work before each track day - oil change, fuel maps, additional weight saving*, filter checks, suspension & chassis setup, wheels & tires and so on and so on

I scrapped the blue accent idea (or rather decided against it from the beginning) entirely and have decided firmly to go for red accents throughout. The rail colour really doesn't matter in the grand scheme of things, but I'm thinking the SS one is the more sensible option if I do want to attempt a re-anodise. It's £140, whereas the HKS kit is a stupendous £280 because they're discontinued and rare now.

The TEIN ones aren't full race shocks though, they're street ones designed to be good on track as well, when adjusted properly. I wouldn't dream of putting on full race shocks - mainly because of the cost, but also because as you said, they're far too hard on public roads and there is nowhere near as much adjustment in them. As I've said, the TEIN coil overs are adjustable in a plethora of ways, including ride height, damping force (16 settings) and you set camber and castor as well, if you have the necessary top mount for them to alow it - the ST205 kit comes with these as standard. All in all a very complete, very high performing and long lasting set of shocks by all accounts

*I'm planning on having rear speakers and subs glassed into a removable frame - bolt in, bolt out just like the door bars of the cage.

 

Every thing is sounding pretty good so far

Easily removable audio system is a nice idea as well, there just needs to be at least 3 strong mounting points to prevent vibration/maximize bass - the sub(s) should also need be facing rearward. You might want to design it to suit fitting behind the rear seating area, that way it's easy to also whack in some rear seating if needed. If you want a longer play time, a second battery could be attached to the removable box as well.
You're probably going to use an mp3 player of some sort for the audio source, no need for a heavy head unit.

The amplifier(s) + peltier climate could easily be powerful enough to draw 1kw+, so you'd want a higher capacity alternator. You should be able to find some nice powerful ones from a 4x4 or ute, maybe from a wrecker or a reconditioned unit from an auto elec, etc.

You know, those fuel rails are pretty expensive, aren't you tempted to just grab some cheap aluminum tubing, drill and tap a few holes, sand and paint the tube any color you want, whack on a couple of barbs and mounting clamps, job done

 

Removable rear seats would be nice, but I'm not sure I'd want that. It's more a ride for two people only, on the track or on the street, if you catch my drift Nah, just kidding... I might go for it in the end and add a couple of quick release rails for two in the back. It would be handy for road trips etc, although at the moment I'm not sure how much of that there's going to be in the GT4. Probably would come in handy if I was driving it to a trackday with a few mates. Pop the seats out at the track and away we go I've been thinking about it though, and for a proper trackday (like if I went to Combe or Donnington to compete in a "run what you've brung" event) I'd like to be setting most of it up here and putting it on a trailer to take over. Maybe that's overkill, maybe not. I have a lot more pressing things to worry about before that, like getting a car!

I think the speaker assembly will have to be mounted on rubber bushings. I'm not necessarily talking about mounting it to the cage, I think just mounting it to the floor pan should be fine.

You're absolutely right about the power, I'll need much more than a relocated battery sitting in the back and the stock alternator. I'll have to put a much beefier alternator on as well as change all the stock wiring to zero gauge, and I'll probably have to add a second battery for the audio system - as you said, that'll be integrated into the speaker frame so that the extra weight comes out along with the speakers - no point in it being in there if it's not powering anything.

Insert "Not sure if serious.jpg" image here"

The stock fuel rail is run at a pressure of 43 PSI... Mine is going to be run off a Walbro fuel pump and will be pressurised at about 45-47 PSI... I really wouldn't like to be depending on my fabrication skills to hold all that pressure and £600 worth of 1000cc injectors into the head!

Here's JamieP's (insane) Supra gauge during a 0-190mph run. Note that his fuel rail pressure drops by almost half when he's on the throttle, and climbs very rapidly back to 45 PSI off throttle. That's an increase from 1.7ish to over 3 bar in seconds!

 

If you think you're more likely to use the hatch for carrying loads, such as track day stuff like spare wheels/tyres, jerry cans of fuel, etc, then better to design the audio box to suit the back seat area.

There's plenty of rigid sections of the floor pan the box can be bolted down to, but mounting it on rubber bushings will absorb some of the bass... sure it might be a bit of a moot point whilst the engine is running, for the engine and exhaust vibrations will be vibrating the car, which is absorbing some of the bass anyway, but I wouldn't want to make the bass any worse by mounting the box on rubber.

And sure I'm 100% serious about making your own fuel rail!
There's no luck or mystery around it, plumbing high pressure fuel lines is much easier, solid and reliable than plumbing stainless steel braided brake lines, or worst of all in my experience: domestic water plumbing, but hey, you don't have to make your own fuel rail, no pressure (No pun intended)

I thought I'd also mention that you'd need to ensure the fuel lines from the fuel rail to the petrol tank and pump are all large enough, but perhaps you already know what fuel lines and pump you're thinking of using?
I don't know if the GT4 Celica petrol tank is well baffled either?

 

The boot will be used for carrying loads at some stage, for sure. A spare set of wheels with different tread tyres, fuel, tools etc as you've said. Ideally I'd like to make it all modular, so that if I want them, I can have rear seats in the normal position, with either the speaker system or equipment in the boot. Or, if I don't need rear seats one day, I could put the speaker system in their place and still have equipment in the boot. I'm not sure how do-able that will be, but that's the ideal setup for my car. I may not even bother with rear seats at all in the end... I honestly haven't decided on that yet.

The reason I mentioned rubber mounts for the speakers is because I'm afraid the audio box will get shaken to pieces by the engine, exhaust and travel vibrations if it's just bolted to the floor pan. If I do it, I'll do it right. It's going to be a pretty nice unit - bodywork matching glass fibre surrounded speakers and subs, amplifiers and capacitors mounted on custom illuminated plexi panels etc I wouldn't want it getting damaged by nasty bumps and rattles!

I'm definitely not going to tackle fabricating the fuel rail myself... I've heard of cheap rails allowing the injectors to lift and doing all sorts of damage. I know it can be done from the little research that I've done since you mentioned it, but honestly it's not for me. I'll bolt on a good, tried and tested rail and like everything else in the car, be 100% sure that it can perform how I need it to.

I hope to use a tried and tesed fuel setup - a Walbro 255 lift pump, Aeromotove A1000 pressure pump, Aeromotive 40 micron filter and another Aeromotive 100 micron filter. I'm not sure about fuel line size at the moment, I'll have to enquire about that but I know that I'll be using stainless braided lines. I have been playing around with the idea of a fuel cell and swirl pot, but realistically I don't have the space for them if I want to do the other stuff that we've been discussing. The GT4 tank is reasonably well baffled, as you can see here. I'm going to make do with it in the beginning, and if I really take to racing it a lot, I'll re-visit the fuel cell and swirl pot idea.

None of this is going to be pertinent for a long time yet - as you know, I plan on building the engine first, then building the car, then bringing the two together, but it's good to bounce ideas around now so that when I come to do any of this stuff, I have a good game plan and plenty of options

 

Oh yeah, it would be awesome to make the audio box so that it can be mounted either behind the front seats, or behind the rear seating position, maximizing your options!

I bet if you decide to setup the car so that rear seats cannot ever be installed, then many occasions will come up where you wish that rear seats could be installed, and vice versa.
Murphy's law
Fair point with the vibrations possibly damaging a fiberglass box over time... especially since it's probably going to be fairly large and carrying a fair bit of weight, so rubber mounting is probably a good idea.

The standard fuel tank has a decent amount of baffling, it's ok.

 

Surely a proper cage isn't going to let you use the rear seats? Should be replacing that whole area with X-bracing and tying it into the rear struts.

 

Well, you say "proper cage" and I know exactly what you mean, but I had intended on attempting to get away with a non-intrusive cage... If I can't, I'll have to call her a two seater and just have the option of the removable audio gear (which, if it's X-braced, will be bolted to the cage).

We'll just have to see what happens when I get it. Everything is subject to change but as I mentioned earlier, it's brilliant to bounce ideas around at this stage so I'm not diving in at the deep end when I eventually get my hands on a living, breathing (hopefully!) 'Four

At the moment I'm trying my best to deal with a very unhelpful breaker over in England, who seems to think that when he lists a picture of something on an auction site and gives a very vague description mentioning that some of the stuff is not included, you're supposed to know exactly what he's including in the sale. I don't use the word noob very often, but seriously...

 

I love the idea behind a non-intrusive cage, I've been dreaming of the same thing for my 106 (since it's made of paper-thin metal and crumples like a foam cup in an accident), but unfortunately it doesn't always work.

On a car which you intend taking onto the track with big power I'm not sure I'd want anything but a genuine motorsport-proven cage. The Safety Devices one for the Celica looks fairly decent with quite low door bars, but unfortunately it's for the previous series of Celica...

 

I would love it to be non-intrusive to give me those options, but as you've quite rightly said, when it's going to be a track car and driven "in anger", I'll need to have the right safety equipment. I certainly wouldn't like to be out on track in it without knowing that I have the best gear around me for protection. I haven't even looked at prefab cages for it yet. To be honest I sort of assumed that being a 17/18 year old car, there wouldn't be any prefab kits to suit it and I'd have to have a custom one built to my own spec. I'd like some input on that if anyone has any suggestions for prefab kits that fit the 6G Celica. I know absolutely nothing about cages... I wouldn't know a good one if I was sitting in it!

I think I'm starting to get my head around what turbo setup I want now. I still have to either find a manifold to suit or decide that a custom one is going to have to be fabricated to suit this setup, but I've decided on the charger, valve and gate at least:

- Garrett GT3582R (Twin Scroll)



- Turbosmart 2011 Hyper-Gate 45 wastegate (two of)



- Turbosmart 2011 50mm Race Port dump valve/BOV



And to control it all, a Turbosmart E-Boost 2 controller



The reason I've decided on the Turbosmart stuff is the rave reviews these products have gotten from race teams around the world, and the great after-sales support that they offer on their whole range. Their Race Port is considered to be the highest flowing BOV on the market

The manifold that I'll need will have a twin entry/twin scroll flange on it to suit the GT35, will need 6 headers (one extra on each side, dedicated to the Hyper-Gates) and will have runners that are flowed 180 degrees apart from each other in the firing order to keep the turbo spooled as high as possible. I'd quite like it to be ceramicoated as well I'm pretty sure that's too bespoke a design to use an off-the-shelf manifold for

Before anyone says it, I know I've chosen the most expensive turbo design possible by going with twin scroll, but I want that for maximum torque and also because I want to maintain the GT-Four's "Twin Entry Turbo" status. A 2.16L engine with a twin entry GT35 should produce enough torque to spin the earth

 

As far as pre-built cages go there doesn't seem to be much for the 6G, there's an OMP one which looks quite feeble, and then there's this custom cages one which looks the absolute dog's, although it's more like a clone of the full WRC cage rather than something a bit more track-oriented. I think the best thing to do is check in with someone like Custom Cages or Safety Devices to see if they can advise on whether your ideal cage could be done.

That Custom Cages one is a kit job which needs welding together, so I imagine you could put slightly less beefy door bars etc in if you wanted to slim down a bit on the safety, or as we mentioned before, have removable bolt-in ones fabbed up so you can take them out for the road without risking it on the track.

 

The picture of the OMP cage on that site is only for illustration, it's actually a better cage than it looks, but it's a bolt in which I don't really want. I'd rather have a weld in one like the Custom Cages kit. I think I'll email them and ask whether my desired cage is possible and safe. I don't want to skimp on it, I'd just like to have the option of back seats if it's possible. If I have to lose that option and have a proper cage for track safety, then I'll do so without hesitation. I definitely know that the removable door bars are possible though, because I've heard of it being done on track/road hybrid builds before.

 

Nice turbos Are those blow off valves going to be silenced, or allowed to sneeze loud and proud?
Ceramic coating is more expensive than using exhaust wrap, especially if the manifold cracks and needs repairs, but a much prettier option.

I don't think a super duper cage is needed to be safe on any half decent race track, dangerous is stuff like rallying with trees everywhere or even having cliffs to slide off, or worst of all, there's driving on public roads Oncoming cars, buses, trucks, intersections, you'd be much safer racing on a track with no cage at all, than driving on the roads with a full cage.
Many bikers will actually refer to any automobile driver as a "cager"

For example, i'd rather slide off a corner, slown down in the gravel, and then finally crash into some tyres with no cage, than have a truck, bus, or 3000lb SUV fail to give way and plow into the side of me - a proper race cage will help, but not anywhere near enough

X bracing in the rear seating area connected to the rear suspension mounts, is worthwhile when you've got super stiff racing suspension in there, especially when you're going to be jumping on a rally course, but if you're going to have something that can just be dialed down to use on the roads, then mega suspension braces are unnecessary weight, I'd rather leave the sound system in

The other thing is that the stiffer the suspension of a car is, (including body stiffness) the more difficult the car is to drive at the limit, so if you aren't going to be racing every weekend, it would be pretty easy to spin out when approaching the limits of adhesion.

I'd recommend to keep the car as light as possible, and put in the minimum amount of roll cage to satisfy the requirements set out by whatever tracks you want to race on. You said you wanted to seam weld the car, and this combined with the basic upper and lower suspension braces, you'd have quite a stiff car.

 

The Race Port BOV is quite loud, and I intend on keeping it that way. I'm also considering adding a couple of screamer pipes to the Hyper-gates. Whilst we're on the subject of the dual wastegate design, someone helpfully pointed out to me the other day that I'd chosen two wastegates that were much too big for a twin scroll setup. They were absolutely right - I chose the hyper-gate 45mm when I was still aiming for a single entry turbo - now that I'm using a twin scroll setup, I can get away with two smaller wastegates. I'll be using Turbosmart Hyper-Gate 38m gates instead. I'll try those with screamer pipes on them and see how they sound. I'm sort of undecided on whether I like the sound of a screamer pipe or not. I know that the two together will be extremely loud, and when you add in the BOV there's probably going to be a lot of noise there. That may be nice or may annoy me, I'll have to hear it first to decide.

The turbo system has been designed to perform though, the sound is entirely secondary. It will probably sound pretty "gnarly" anyway, depending on what cat-back system I go for (another thing that might be entirely custom but has yet to be decided upon).

I'll have plenty of time to ponder over the cage situation. I know that I won't be at that point for at least a year. Certainly the Custom Cages one that Krikkit linked to is serious overkill for what I want and need. That's pretty much a WRC replica cage. Much less will do for me, but I do want it to be entirely welded other than the door bars. The bolt in cages are mostly crap from what I've heard. I think that a good cage specialist should be able to put enough bracing in there to make it track safe and legal for most of the popular UK trackday destinations, and still light and minimal enough to let me have some speakers The seats will probably not be possible though, from looking at GT4OC members cage setups.

 

The turbo whine followed by the dump valve woosh always puts a smile on my face. The scoob has a titanium tip kakumei 3" catback exhaust and sounds amazing. It occasionally sets car alarms off when you drive past You do feel a bit sheepish trying to park the car with out waking the neighbors in the early hours.

 

DRB: That's a really nice sound from the Scoob! Mine's not going to sound as deep as that because it's not a boxer engine, but the exhaust cut-out should allow me to run a slightly quieter setup on the street. I don't really want it that quiet to be honest, only at low throttle. I was thinking of a titanium tipped full 3" SS exhaust for the GT4. If I could, I'd put a HKS racing turbo back on it - they sound awesome and perform fantasically. With the cut out for the track I'll be able to have it massively shortened with just the manifold to downpipe to sport cat to atmosphere

I trawled through GT4OC for the past half hour and eventually hit paydirt on the "pictures of complete cages" situation. It seems this one is an original Toyota Team Europe body with a different looking WRC spec cage (custom fabricated of course) welded in. Those door bars look removable to me, and there's still some room in the back Still way too much cage for my needs, but this link is pretty much roll cage pr0n

Click this tidy link!

 

Love the twin pulse beat of the Scooby
I can imagine how loud she'd be at high rpm under load Once upon a time I had a 3" exhaust on my Mitsubishi, the thing sounded like a rally car, and it would set off car alarms as well. I got sick of it after a few months however.

I was just thinking about the QTP exhaust cutout you linked earlier Unicorn... I'm guessing that the hot exhaust might just cook the crap out of it
The gearbox and motor isn't linked to the valve via thin steel cable or anything like that, it's all right there, and I'd be really surprised if it lasted for very long.

But since it seems you want to practically run an open exhaust on the track, well then how about removing the unwanted half of the exhaust system when you want to go racing?
You're going to be jacking up the car in the pits anyway to tighten up the suspension settings, removing ~half the exhaust system is probably going to take ~15 minutes or less, and take off another ~10kg+

I wouldn't worry about what sort of cage other people put in their cars, I'd put in what suits me.

 

I have it on good authority that the QuickTime Performance Cutoffs are more than durable enough to handle high performance engines and high temperature exhausts, both on the street and the track. They're used on track cars with over 1000bhp engines, including 10 second and below dragsters. I think it should be fine on my own car They also do a downpipe version, a downpipe with a cutout at the bottom of it before the cat - that's an open header port! I like the idea of removing the rear portion of the exhaust for extreme track use, although I'd like to use the cutout on it as well for handiness and for adjustable port opening (the electric cutout can be opened by any value from 0-100% via the electronic controller).

I'm almost certain that the cage is going to be 100% custom at this point. I don't think any of the available kits can be adapted enough to suit my own needs. The pictures in the link I posted are a nice reference for what can be done in the GT4 though The fact that I've got one more thing that more than likely will need custom fabricated is no problem, I expected that from the beginning anyway!

 

Very interesting, I wonder how long those things can last?
Fair enough if you can't be bothered taking off the exhaust every time you want to race, I'm just surprised the valve's gearbox and motor are so closely located to the exhaust pipe, but if they're engineered well, they should handle the heat I guess. If you take Yamaha's EXUP variable exhaust valves for example, a small electric motor actuates the exhaust valve via two thin steel cables, just like brake/gear shift cables on a bicycle, so the little electric motor and it's gearbox don't have to deal with any heat at all.

Adjustable port opening is great for boosting low end on the street, but that would mean having the valve installed in line with the exhaust, not as a valve allowing a bypass, or else as the valve begins to open, the car would be too loud for street use. There's also more heat for the exhaust valve and it's nearby mechanisms to deal with in this arrangement.
Adjustable port opening isn't much use on the track, for you shouldn't be spending much if any time powering away from low revs on the track.