Hyperblade's KP61R - Toyota Starlet with Honda K20a

[Hyperblade]

Discussion: https://oldschool.co.nz/index.php?/topic/57479-hyperblades-kp61-racecar-beams61-discussion/

 

Moving over my project from the club-k forums to make it a bit more public for those interested.

So it started when I brought this 1984 Toyota Starlet Racecar, I wanted something I could drive to the track, while still being safe during racing, hence the roll cage.

It came with a 2L Altezza 3SGE BEAMS engine with the 6 Speed box, already in it and a really good build history from the original owner.

Sale thread here has some more details: https://oldschool.co.nz/index.php?/topic/38220-fs-1981-kp61-starlet-race-car-certifed-homologated/

More to come...

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First time out on the track

Managed to break the front splitter going off road when the rear came loose.

But after removing the pieces got some good laps in.

 

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So after some time off the track to fix a leaking rear main seal, and replacing a universal in the drive shaft, had a pretty big moment when I blew the brand new rear driveshaft universal...

 

 

It had so much force it pulled the driveshaft hoop mounting plates through the floor of the car...

And broke the seat brackets

 

 

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So after sorting out a new driveshaft.

We then spent a few months trying to find out why we were getting significant drive shaft vibration, which got worse and worse as we tried different things.

Eventually narrowed it down to the pinion being bent from when I broke the drive shaft...

So new 4.7 Crown wheel and pinion put in and we finally got it running on the track properly.

 

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Finally got out to my first ever Pursuit Sprints and had a blast.

 

 

And it even drove home which was a bonus.

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So after dropping my PB down to a 1:43.5 on semi slicks, some funny stuff started happening electrically.

Also broke the dip stick to top it all off...

On the bright side, the front splitter was finally repaired and put back on the car.

If your wondering why the repaired splitter has a split down the middle, that's because they are a nightmare to fit to a KP61 as they are too wide, we left the split so it would break there again if I went off road, amazing foresight it turned out...

 

 

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At this point a few things were annoying me with the car.

• Speedo stopping working, then worked again, rest of dash continued to work fine
• throttle lag, put foot on pedal, nothing happens, then ecu decides you do want to go and opens throttle, this made clean starts impossible.
•  3500 rpm to 5000rpm lacking power (most likely caused by ECU not liking pod filter)

So the decision was made to put a Link ECU in it.

So out with this.

 

Being a race car I needed access to the main switches etc, so the mock ups begin.

The other thing with the wiring that was a pain was the relays/fuses were down the right of the accelerator pedal, behind the roll cage, a right PITA to work on.

So since we were tidying up the engine wiring, we moved all fusing/relays/controls to the passenger side on a new distribution panel.

 

 

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While we were doing the wiring, quad throttles, with trumpets, adapter plate (sq engineering) and filters came up on trademe, I couldn't help myself, lucky they just fitted...

Move the battery to the back

And started installing the new loom

 

After many months we finally finished the wiring.

 

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Managed to get the car started on a the Link Base Tune, and drove it down to get it tuned.

 

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So at this stage I had no dash, my intention had always been to go with something aftermarket, but I couldn't bring myself to pay $2000 for a black and white dash, so the hunt begin for the right solution.

First option was to slow (OBD2, Bluetooth and Android tablet)

So I moved onto a Windows tablet running PCLink, this worked well but I couldn't charge it at the same time as having it connected to the ECU, but i did end up racing with it and it lasted fine to my surprise.

But it wasn't a long term solution so I ended up with this tablet for $200 with dual USB ports

It works really well, I have a hard wired shift light/warning light above the tablet, so the tablet is just for temp's and pressures really.

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So got out to my first ever club day in Feburary this year.

Had brand new 205/50/15 Hankook Z214's which were amazing for grip.

New ecu and quad throttles transformed the car, throttle lag and hesitation all gone, and power from down low all the way to 7000rpm, my starts off the line were a lot more consistent.

New PB of 1:39.2

Car felt a little bit weird in some corners as it now had so much more grip and power it was starting to lift the inside wheel, a lot...

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With the new tune I had also put some Mintex Pads in.

After one race day, was decidedly unimpressed when I checked them...

That's front AND rears toast.

Cue the 4 month upgrade of the brakes and wheels...

 

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Decision was made to try and bring the cost down of the consumables (Pads and Tyres)

So I dropped the wheel size down to 13inch so I could run TRS slicks.

Old wheels and tyres weighed 17kg each, new ones are 12kg.

New Wilwood Calipers on the front to fit the new rims.

For the rear, since I'm still running standard AE86 axle I have waterjet cut down some Wilwood Polymatrix pads to suit.

Of course all these changes meant the cert plate was no longer valid, so the decision was to make the car a dedicated race car, which saves having to do 6 months warrants, authority card and on road insurance.

 

 

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So 1 new car trailer later

And a new tow car...

My brake upgrade to bring costs down was ready to go...

So out for a frustrating couple of test days, where the brakes were spongy one corner and rock had the next, finally tracked it down to the rod going into the master cylinder (which i had replaced) was slightly sticking so the pistons were staying out, once that was solved the pedal felt much better.

 

So onto the first Canterbury Car Club - Club Day 1 where I had an awesome 3 races.

 

Oh so close to winning the handicap race, pipped just before the line.

 

Car was handling much better on the new size tyres, and brakes were more consistent although I noticed some fade.

With the new smaller wheel size however i'm now hitting the rev limit not far after the finish line in 6th, so have to feather it at the limit, which is annoying.

So once back home had a good look at the temp paint.

Front:

Rear:

So looking at the paint colour change (we want between green and orange) we can see the didn't set off the 550c paint on the front (which has no cooling) which is great.

Rears however started to set off the 630c paint which is not good.

 

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So normally you would sort all the issues out for the next race, but I got busy, so did bugger all on the car

So next club day came around, and it was stinking hot, 23c...

So me in my 3 layer suit was siting on the dummy grid thinking I really should have got round to the driver cooling... 

Race 1 went ok, but I noticed the temps were getting up on the car, and driver, and brakes.

Race 2 was the first time the car has ever been behind another closely for extended time, engine temps really didn't like that (104c) so the rev limit dropped on me (safety mechanism when the car gets to hot) first time it's happened to me and really annoying.

Race 3 wasn't great, I ran with the fan on the whole time, but temp's just kept climbing and the rev limit lowered for the last lap which was the worst timing.

 

Looking at the temp paint, the front's were no longer coping.

There isn't a whole lot of space for the calipers in the wheels.

 

It looks like with the higher ambient temps during the day, the brakes got hot enough to expand and gouge my wheels :/

The car is still fairly heavy (full glass and doors) so that's not helping the brake situation either, other guys with starlets are running street pads and no cooling.

So new list of items that I must sort out for the next club day in December

• Cool Brakes
• Cool Engine
• Cool Driver

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So up to present day.

The rears are AE86 disks and have a shield around them which holds the brake line and is also attached to some steel which the caliper is bolted to.

Time to get rid of it so the hot air has somewhere to go. So some very careful cutting with an angle grinder we end up with this.

That should help, if it's not enough then might have to look at vented disks.

At some point I want to get fiberglass doors which will have windows that won't go down, so driver cooling will get worse. So time to duct some fresh air.

So first need to fit some Polycarbonate rear windows.

I now have a NACA duct being fitted to the passenger side which I will then duct to the dash and point at me.

 

So for the front brakes, I've been holding off cooling them as I have a new body kit to go on (as the front splitter has brake cooling holes built in.

The car came with a kit that doesn't really fit, you end up taking a section out of the middle of the splitter to reduce the width as the splitter does not fit nicely to the flares, the angles are all wrong and it's all under stress.

 

I also want to be able to get spares so I got some new ones locally that are made for the bug eye and which I can get more of easily.

As you can see, miles off from fitting.

Now having never done this type of work before, cue much swearing as I try and get them to fit.

So 2 weeks later (many nights of just walking away before I make this worse) this is currently where I'm at.

It's close but not quite right (and of course doesn't line up with the old flares mounting holes), you can see however the fitment of splitter to flares is 100x better.

I'm currently trying to work out if I can get the front higher without chopping to much of the splitter or chassis rail seams (which stick out).

 

 

[Hyperblade]

So while I was deciding what I was doing with the front splitter I sorted out a few other odd jobs.

First one was a decent rear view mirror, I got this mirror bar locally, but the mounting wasn't great, so AliExpress to the rescue for some fog light brackets and a bit of chopping, i now have a really good mounting, here's hoping vibration isn't to much of an issue.

 

 

Can now see out each rear side window from the drivers seat, where as before I could only see out the rear window.

 

To finish off the side windows I painted a black border on the inside, definitely worth doing they look really sharp now.

 

Got the hole cut for the Naca duct.

And all finished.

 

Managed to get out to view the Speed Festival on the weekend, great turn out of starlets for Shellsport and SS Cup. (and also saw @pe-arce's Beams powered escort battling it out on track which was awesome after following the build online).

 I took my tape measure out to measure the front splitter height on the starlets and most were running around 80-90mm clearance to the ground, (some were on 13 inch tyres some 15inch) so with that to aim for I finally got mine sitting right at around 92mm (at some point I will install an undertray and I can always lower the car more as I have more clearance on the tyres)

I just have to finalise mounting to the guards (slightly off the old rivnuts so have to remove them all and nut and bolt for now) but making good progress.

Next club day is 10 Dec so everything has to be done before then!

 

 

 

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So a fair bit of work has gone on for tomorrows race day.

Previously the brakes had been overheating front and rear, you can see how tight a space it is to work with

So off to Brent at Palmside to sort out the brakes as that's beyond my ability.

Some nice backing plates later it all fits in quite nicely.

While it was in the workshop it was time to finally get rid of the old seat, it had a sprung base and back so my spine was bent in it, and I would get a sore back straight away when I tightened the belts. Also my head hit the roof, so in an accident there was a high change of breaking my back.

Fitting a race seat to a starlet can be a challenge, but the Racetech 4009THR ended up fitting perfectly, it's dropped me a lot lower, and with out the cushion I now have 10cm + of head room, which is a small miracle, as it's frustrating hitting your head on the roof/rollcage. Brent put in some proper mounts (the nuts on the old ones were starting to pull through floor) so it's really solid now, need to get the steering wheel slightly closer but that's easily sorted.

While it was there new 4.3 crown wheel and pinion was fitted to replace the 4.7, which will stop me hitting the rev limiter just after the start finish line.

Got the splitter and flares painted and all fitted up.

One of the big issues I had when i was last out (23c day) was engine cooling, it just kept climbing and eventually the ecu started limiting the revs.

So time to fit an oil cooler to free up some of the cooling capactiy of the raidator (engine runs oil to water heat exchanger). 
At the same time i've opened the front of the car up by chopping the bumper, and fitted blanking plates to force the air into the raidator/oil cooler.

Chopped the engine cover cos racecar/stop heat building on the coils.

So with the race day looming the only day to practise was yesterday, when the temps hit 33c, with trepidation, but knowing it would be a good test of the car went out for a couple of runs to make sure everything was in order.

It was really really really hot in a 3 layer suit, however the car performed really well.

In clear air the coolant temps didn't go over 92c, the brakes didn't overheat, and I just lasted the distance.

So really happy with that.

Pretty Graphs!
Last Race (23c)

Shakedown (33c)

Will see how it goes tomorrow, but the next major items are a new exhaust and cold air intake with filter (so can remove the trumpet socks).

[Hyperblade]

So the club day 3 went well, always good when can drive the car back on the trailer.

Positives

• Back no longer hurts sitting in the car, new seat works well, although has blocked my rear view vision a bit.
• Car only hit 96c engine temp, while in traffic (28c day) so very happy with that.
• Brakes were lasting better.
• Handling was much better after corner weighting the car and fixing the cross weighting

Negatives

• Car felt a bit sluggish with the new diff (4.3 from 4.7).
• Car felt like throttle was sticking (was idling higher in pits until i gave it a rev and it dropped), even though it wasn't.

However looking at my best laptimes from the 3 different races vs the last club day, paints a different story.

Club Day 2

• 1:39.040
• 1:41.980
• 1:40.270

Club Day 3 

• 1:38.824
• 1:39.307
• 1:39.911

So in a considerably hotter day, I've actually gotten faster. Even though it felt like i was slower.

So the next job's to do before the next club day.

• New side exit exhaust system with new headers (currently running stock exhaust manifold)
• New cold air intake, getting rid of the trumpet socks
• Replace the fuel system with a fuel cell which also means new fuel pump, filter, FPR (can do it after I get rid of exhaust)
• New Tune
• Replace the cheap aliexpress idle up valve with a genuine one as I think it's staying open when it shouldn't.
• Buy a filter for the go pro so that you can actually see the track.

I'm hoping to get a little more HP out of those changes, especially nice would be getting some top end back, as it's sluggish after 7000rpm.

Long term I need to lighten the car some more to ease the load on the brakes (most of the race starlets down here are around 700kg or less and have to run street pads as they can't get enough heat into them). Currently it weighs 880kg with a 55/45 (front/rear) weight distribution.

Videos:

 

 

 

 

[Hyperblade]

As is always the case, of the list of things I wanted to do before the next club day, I only ended up doing a couple...

First job was new headers and exhaust, I had been running stock Altezza 4-2-1 headers (shortened at the 2 section) 2.5 inch steel system with two old mufflers under the rear diff and out the back. This was a pain as it was one piece all the way from the headers back and was bolted such that it could not be removed without major work (infact I never had it off as it was to hard).

So the goal of the new headers/exhaust was:
* Make it eaiser to maintain. 
* Side exit so no more diff issues
* Gain HP
* Save weight

I was "lucky" when I spotted some TRD headers come up on Yahoo Japan in really good condition.

Unfortunatly when we went to fit them, they ended up being 100mm to low, and there was no easy way to modify them to fit

However they gave me accurate measurements, so on to plan b which was to get some custom headers made to the same specs. As the TRD ones were meant to give 13kw across the rev range.

Being Made:

All Wrapped:

Next was to get rid of the indvidual trumpet filters. While I would like a cold air intake plenium, I just didn't have the time or desire to make one at the moment, so decided to go with a Pipercross filter and a backing plate to suit.

Now space is quite limited in this area, so both the backing plate, filter and firewall had to be massaged to fit in and still allow the bonnet to close normally. 

Luckily there was enough meat on the filter to take the plastic frame down while still keeping its integrity, it means it's no longer quick release, but it will do the job.

 

So then off to the dyno for a retune.

Old Dyno Results: 134.6 kw (180hp) @ 6929rpm, 215 N-m @ 4560rpm (Hub Dyno)

 

New Dyno Results: 149.9 kw (201hp) @ 7250rpm, 235.4 N-m @ 5150rpm (Rolling Road)

 

Very happy with that result!

So off to Club Day 4 with some new tyre pressures to aim for too (after advice from someone in the know) now running 21psi hot instead of 24psi.

Race 1:

Race 2:

Race 3:

So previously my best laptimes across the 3 races were:

Club Day 2

1:39.040
1:41.980
1:40.270

Club Day 3 

1:38.824
1:39.307
1:39.911

Club Day 4 Was:

1:37.187
1:37.400
1:37.424

New PB of 1:37.187 down from 1:38.824.

What was most pleasing however was in race 2 every single lap was in the 1:37's where as previously they had varied quite a bit, I think that's mostly down to tyres as they used to feel like they were getting slippery in final laps. 

Car is now lifting it's front left wheel a lot out of the corners due to the grip, acceleration, and in some cases the back tyre was also lifting. It's performing a lot better now, and I can actually keep up with the competition down the straight so have a chance of getting them under brakes, where as before I was just to far behind.

Next major items before the last Club Day 5 are around aero and improving the drag/downforce:
* Duct cold air to the filter.
* Front splitter/tray
* Rear diffuser (If I get time)