Sirion AWD conversion/ autocross build


the ecu mod is a prettysimple thing, the ecu calculates rpm using the signal from the CPS against time. The crystal in the ecu is the “time”, to put it simply if you overclock the ecu 10% then one minute is actually 54 seconds inside the ecu. So at say 8000 rpm the ECU thinks the motor is only doing 7200. This is the reason why its not particulary safe to go to extremes with this mod, with a 10% overclock your motor is doing 8000rpm with fuel and timing for 7200. After 10% you start to have communication problems betweenthe ECU and other systems like immobilizors, ABS and scan tools. I was hoping to go 5% to bring the limiter up to 7850rpm, but i couldnt find the right crystal. With the small increase of 3-5% timing and fuel is not such a big problem, this was my reason for installing the FPR so fuel could be increased slightly, and with the advanced crank sensor wheel i have more timing across the board and i wont lose any timing at higher rpm. This is and oldschool hack that origionated from the old Cressida scene, when people didnt have access to aftermarket ecu´s, and they were able to raise the rev limiter and in most cases also gained power due to the stock fuel map being too rich for the old 7AG motors. I have some left over crystals if anyone wants to try it out for themselves, at first i ordered a 4.19Mhz (approx 4% faster) crystal thinking the ecu ran at 4Mhz, then after discovering my ecu ran at 6Mhz i bought a 5pack of 6,144Mhz crystals (approx 2.5% faster). I can do small packs with a crystal and a switch for EU2.50 plus postage if anyones keen, im not going to use the leftover crytals anway, and i have surplus switches because the minimum order was 10 pieces :sweat_smile:


if i sent a pic of a move ecu could you let me know if it would work on that? I would be keen on one.


Yeah you just need to take the cover off and check the number on the crystal


Ohhh great ECU mod … I want!!!



If I take a pic can you show me what I’m looking at and if it has this Magical Dark Krystal on the board?


judging from the photos my ecu is 4 MHZ true?

I am interested in a pack :star_struck:… to solve fuel problems it’s not possible to install a SAFC in sirion? :thinking:


Hi, no problem, I can post you a 4.19Mhz and a switch. Will raise the limiter approx 4.5%. Just pm me your details :slight_smile:

Also I saw the bracing you made on your build thread, I was wondering if you had any more photos, and how did you fasten them to the chassis?


I sent you a PM

I was looking if I had pictures of the fastener but I didn’t find … the next time to disassembleit up I’m going to take pictures with more details.

In any case we fasten to the same control arms bolts and where there was no where to hold we soldered a nut to the chassis to support it.


Hi guys, not a real lot been happening over here, the last race was cancelled and the next is one week from now.
Ive managed to adapt some ford mondeo shocks to the rear, they feel alot better suited to the springs I have in, but possibly a little too hard.
Ive been looking at options for coilovers, not alot available but evo 7 coilovers might work and theres some cheap chinese options available for around 100 bucks that could be used for mocking up/ testing.
Also been looking into better gearing, ive realised since the transfer case is driven from the differential basket any change to the final drive in the front is automatically translated to the rear, meaning all I need is a bot from the 1,0 litre sirion for parts. Something ill get onto soon.
Otherwise the old girl has been going well, and im looking forward to giving it hell again next weekend :slight_smile:


Video from the race last weekend :slightly_smiling_face:


2sec gap, well done. Seem to be turning okay. Much more power?


Yeah I managed to close the gap alot by the last run but unfortunately wasn’t enough. Overall my times are above average but compared to others in my class im terribly slow :pensive: I have ordered a box of 2.5" coilover springs in various lengths and rates and im currently bidding on some el-cheapo Mitsubishi evo coilovers. I will adapt the rear to take coilover springs and fit a watts linkage using parts from PT Cruiser which are relatively inexpensive. I will fit the coilovers to the front so I can adjust camber/castor, height, spring rates and dampening, its not ideal but will be a hell of alot better than the current setup. I will also attempt to use parts from the rear coilovers to make some height and dampening adjustable shock absorbers. Ive also been eying 1.0l boxes on ebay, they are relatively cheap and the gearset will fit in the 1.3 housing giving me slightly better ratios. Also planning to buy a set of 13" rims and some used slicks. It will be a long ordeal that I will attempt during winter


Could you tell if you are up on power?


Yeah it felt better until the engine light came on. Unfortunately I bumped the circuit breaker in the pits and when I turned it on again the light was out so I wasn’t able to read the fault code. Im pretty sure it was an O2 sensor fault because the exhaust has a leak, but I cant say for sure.


NWD-Cup 2018.pdf3a.pdf (32.4 KB)
Not doing too bad! One more race day left then the season is finished. Videos from the race last weekend coming soon!


Second, well done. Beating the Polos, love that. Fitting Konis to a Polo at the moment. Hating every minute of working on it.


@Mr_Gormsby do you think something like this would work for the pivot on a watts link?

I would cut a diamond out of some heavy flat bar and mount this in the middle. Thoughts?


It already has a panhard rod. How much rear wheel travel do you have - is it less than factory?
Which way do you plan to mount the Watts? Will the centre pivot be diff or chassis mounted?


Centre pivit will be on the diff, I will simply weld on another factory panhard bar mount on the left side, 2 short bars with heim joints and a pivot in the middle on the diff housing


I have seen plenty of kits available but all rather expensive and aimed at the hotrod community, way overkill for me. I could easily make up something plenty good enough and have change left over from 50 bucks, im just looking for the easiest solution for the pivot, weather it be a poly bush or bearing of some sort.