Alto RS-X performance

[Almost a Mini]

OK, for anyone who may be interested, I've recorded a few G-Tech based performance figures for my RS-X. . .
Fairly repeatable 17.3 second 1/4 mile and 9.8 sec 0-100. . .what a demon!
These figures are for an absolutely stock '87 RS-X (DOHC F5A, 5 speed) with a *filthy* factory air cleaner and factory 1&1/4 inch press bent exhaust.
Add to this the fact that the car hits it's 120km'h speed limiter at 13.5 sec through the 1/4 and wheelspins pretty badly on it's cruddy 145 tyres and 17.3's start looking OK.
So, once I get rid of the limiter, things will improve straight away. . .a decent filter and exhaust should make a big difference too.
And, as standard, it appears the motor only runs 7psi of boost, also. . .so there should be scope for improvement there as well. The Alto runs the same RHB31 turbo as Cappuccinos and they run 11psi as standard - so I should be able to up boost that far comfortably for a start. . .then we'll see what the standard ECU/injectors/intercooler can deal with before things start leaning out and/or getting too hot. . .
I'm *really* starting to like this little car. . . .

Pete in Perth

[Brayden]

If the F6A uses the same turbo as you mentioned is on your F5A then you'll be pleased to know that there are at least two MightyBoy's running ~15psi on stock internals with no other mods besides ECU, intake and exhaust.

[alex_mkd2000]

i know this thread is pretty old, but I searched 'F5A Turbo' and done some reading.

While reading your post, I found this a bit odd:
0-100kph = 9.8 seconds
0-120kph = 13.5 seconds

I know its only a little engine, but it is turboed, why does it take almost 4 whole seconds to giddy up an extra 20kph? I read a post from another alto owner who claimed to have the stock limiter at 140kph, maybe thats what you meant?


Either way, them times should pretty promising, have you done the mods you intended, and if so have you re-timed it?


Thanks

Alex

[Brayden]

While I doubt those times are completely accurate, the faster you try to go, the slower it will accelerate because the motor has very little torque.

[Almost a Mini]

i know this thread is pretty old, but I searched 'F5A Turbo' and done some reading.

While reading your post, I found this a bit odd:
0-100kph = 9.8 seconds
0-120kph = 13.5 seconds

I know its only a little engine, but it is turboed, why does it take almost 4 whole seconds to giddy up an extra 20kph? I read a post from another alto owner who claimed to have the stock limiter at 140kph, maybe thats what you meant?

Either way, them times should pretty promising, have you done the mods you intended, and if so have you re-timed it?

Thanks

Alex

Hi Alex. . .
A few things about my original post. . .as Brayden pointed out, I'm not sure how accurate the times are - I was doing these times with a G-tech accelerometer - while these are pretty good, their accuracy does tend to fall off at lower acceleration rates. . .
However. . .when I tested the car it was dead standard - and that included the standard exhaust (about 1&1/4 inch), an internally collapsed muffler and an air filter that looked like it had been soaked in bitumen or something. . .anyway, these problems would certainly contribute towards bad air flow and hence poor performance in the upper rev ranges. Even with a clean filter and bigger exhaust the top-end performance will still be limited. . .valve sizes, turbo inefficiencies, inlet manifold flow restrictions - they all add up to limit gas flow and therefore performance.
With respect to the speed limiter - my Alto is a CA72V (1987) and it certainly is limited to 120km/h. . .I think later Kei class cars had this raised to 140km/h (our '94 Cappuccino was limited to 140. . .). The speed cut was quite 'soft' as well so it may have been starting to cut in before 120 and contributing to the poor performance as well.
I haven't got around to all of the mods yet - after looking at the basic condition of the engine, I decided that a full rebuild might be a good idea - it was probably OK if I was only planning to use the car on the road but, seeing as I'm planning to use it for circuit work, I thought that rings, bearings etc might be a good idea. . .so, I've been spending a lot of time tracking down parts - it's not particularly easy - very few people have any info on the import F5As. So tracking down engine parts as well as fuel and ignition interceptors, suspension parts, brake parts etc etc is taking a lot longer than I hoped (I've also recently had a resurgence in my interest in Minis and have bought a couple more of them to work on ).
BUT, I will get there, and I WILL let the Klass forum know how things proceed. . .

Pete in Perth

[skulloz]

We have been running an turbo Works Alto motor in our Mighty boy for some time now(everyone should have one) and I have now replaced the turbo with a "much"Garrett unit with pleasing results,but as the airflow, is quite low, through the standard head, I plan on either flow porting it or if possible replace it with a better flowing head .
Q1- will the F8A head fit do they have larger valves or are they all the same F5A/F6A/F8A.
Q2- Can anyone help me out with the engine spec of these engines .
Q3- what parts interchange between the three engines.
Q-4 are performance parts available for these engine.
Q5- how do I bypass the speed limiter, my big turbo just starts making some real power and the *&%$##$ limiter cut in and ruins all the fun.

If you own a mightyboy save up you spare cash and fit the turbo motor,you will be MORE than happy with the performance gain ,the only down side is that you wonder how you managed to put up with the under power standard engine.
Mightyboys rule.
regards skull

[Brayden]

Q1 - F8B head has larger valves than an F5A, not sure about the F6A though. SuziSport put an F6A DOHC head on an F8B block, so they must at least be interchangeable.

Q2 - There is a VERY basic rundown of Suzuki Kei engines here:
http://www.tamon.org/?page=guides&id=12 - however I haven't had a chance to add the technical specs yet.

Q3 - Apart from what I mentioned above about being able to swap heads from DOHC F6A and SOHC F8B motors, very little else is interchangeable because of design changes over the years. Even odd things like the import F5A using a different turbo (although same model number!) than the F5B and F6A. Suzuki really did go out of their way to make exchanging parts a very complicated process.

Q4 - The only source of performance parts is SuzukiSport in Japan, but parts from there are very costly. They sell full aftermarket computers, turbo upgrade kits and a variety of other things. Apart from that it is just up to your enginuity to adapt parts from other cars or make parts from scratch.

Q5 - With a full aftermarket ECU. There are no piggy-back ECU's available for the F6A that I am aware of.

[Almost a Mini]

We have been running an turbo Works Alto motor in our Mighty boy for some time now

Factory speed limiter is easy to remove on the F5A (from CA72V Alto Works). . .just cut one wire - no side effects. As for the others, the limiter is similarly easy to overcome but will cause the engine check light to be illuminated. . .*this* can be overcome by fitting a commercially available 'speed cut defender' or, as Brayden said, an aftermarket ECU. Assuming the F6A from an Alto is wired the same as a Cappuccino, the speed limiter wire is violet with a red tracer. . .cut (or switch) this **at the ECU** and your limiter will be gone - but the engine check light will be illuminated. . .

Pete in Perth