I've got a VW 1.4i engine code AGY in my Fox (RSA Fox, elsewhere Mk1 Jetta). Not sure if this engine was available outside RSA. Originally it ran on the MP9 management sytem in the VW Citi Golf. I've swopped the 1300 code GY motor in the car for the 1.4i AGY completely stock running on Gotech engine management. I use the car in our local gymkhana series. We mostly run about a 1km circuit with as many corners as they can fit into the course. It's a very tight circuit and we never get out of 1st gear, thus speeds are low (max 60km/h) and we use a very wide rpm range. Currently the motor revs to a max of 7000rpm. I need some more rpm out of this motor as I'm constantly running into the rev limiter on the gymkhana track. What can I do to make this engine rev higher. The catch is I still need to retain low down torque. The motor don't need to make power to the rev limit, it just need to keep on revving. Any idea's on what I can try to make this motor rev higher. I still have the GY engine so a head swop to change from hydraulic lifters to solid is an option if need be.
I've already got larger slicks than what I would prefer to run. Even 500rpm more would help alot... Cams is the obvious answer, but scared of losing too much bottom to mid range torque and power. One of my fellow competitors has the exact same engine in his car fitted with an estas 272 cam, head work and balanced bottom-end. Problem is my motor makes more power and torque than his upto 5000rpm, where he only starts making more. I've got the advantage low down and in the mid range, I just run out of revs at 7000rpm, where he caries on upto 7500rpm. On short sprints I've got the advantage with the more bottom to mid range power and torque, but on the slightly longer sprints he has the advantage over me with his higher rpm limit.
Already using larger slicks than I would like to in an effort to increase the top speed in 1st gear. But acceleration is suffering with the bigger slicks. I've only got 74kW and 130Nm engine power on tap making it difficult to pull off the advantage of the larger wheels. Been looking into a gearbox with custom ratio's, but gearbox spares and work is really expensive around here. Thus the thought to rather do some engine work instead.
020 1A 4-speed 1st - 3.455 2nd - 1.944 3rd - 1.286 4th - 0.909 FD - 3.941 From my research all VW 020 gearboxes have a 3.455 1st gear. I've been looking into a custom ratio gearbox to be able to use 2nd gear, but the cost to build a custom box is really expensive. To put the cost into perspective, I can buy another car for the same cost of a custom gearbox. So I'm rather looking into engine modifications. Any engine mods I can look into?
This is my proposal for that engine based on your requirements. I am assuming for now your baseline torque looks like the OE red plot and the blue is as a result of the combined updates in blue text. You will be on the same gear set and tyres.
Not sure on the 02K, will have to check. VW SA has a tendancy not to stay with international specs, making it real difficult at times [:^(] Yes, the ECU controls the limiter. Currently it's set at 7000rpm. I've tried raising it, but as little as 25rpm more and the motor picks up either valve bounce or lifter pump up. Not sure how to determine which. So 7000 is the safe limit setting. The motor is completely stock except for a lighter flywheel and aftermarket ECU.
Here is my dyno sheet after the ECU has been mapped, ignore the lower power and torque curves it was only a startup map and cam timing was out 1 tooth. Here is a comparison graph of the same motor with raised compression ratio, gas flowed head, Estas 272 cam, balanced bottom-end with lighter flywheel and aftermarket ECU. Stock vs Modified for this particular motor As can be seen from these two dyno graphs, my standard motor has more bottom and mid range power and torque than the modified one. Only at 5000rpm onwards the modified motor out performs the stock motor. That's what I'm scared of if I start putting in cams. Because we are using such a wide rpm range and mid-range torque I really don't want to loose any, just need the motor rev higher.
Almost unbelievable that 25rpm change in a limiter will hit a mechanical engine limit such as valve bounce. This sounds like a secondary rev limiter, fuel cut or whatever. Valve bounce is a really harsh mechanical noise, once youve heard it youll probably remember it. Exhaust lambda probe is a really useful measurement, as is a rev counter driven by coil pulses.
eye you going to run into valve bounce i remove the rev limiter from the rotor arm on my mk1 gti and only got 20 to 50 rpm more before valve bounce set in your going to need better valve springs that just life you get nowt for free
There is no fuel cut installed on the car, fuel pump runs from the ignition. Still need to change this to a safer method of fuel pump control. The only limiter is the ECU and it has only one setting for the limiter. Mapping has been carried through from 7000 upto 8000rpm, so should go higher than 7000rpm. Just past 7000rpm it really sounds like valve bounce and definitely is a mechanical limit, the sound is horrendous, sound like the motor has let go. I don't know how lifter pump-up sounds like, heard it could be the problem as well. Got a rev-counter installed in the car directly from the coil as proposed, it confirms the rpm as seen in the ECU. Got a lambda probe, just not yet installed. How can this be used to diagnose a possible problem? The car has been mapped on the dyno with a lambda probe, but 7000rpm was the absolute limit the motor could be safely revved to.
My motor has an electronic distributor, would it also have a limiter installed on the rotor arm? How did you remove it? Could you maybe point me to some pictures of this rotor arm limiter, so that I could check that is is not my problem. That is if my motor is equipped with such a device. What better valve springs do you recommend?
no your distributor will have no rev limiter valve springs you could try the likes of supertech and kent and piper
The graphs you put up correlate to what I proposed earlier if you study carefully. There is less than 8Nm of torque between the modified engine and the standard one at low engine speeds. I am also surprised raised compression has not further pushed the torque higher. This can be caused by either mapping or non optimisation of hardware or both. You also have to consider what engine speed you are likely to operate the engine when competing to further understand if this very small loss in this example is really a problem. What I said in in contribution still holds.
When diagnosing a problem, its sometimes best to make no assumptions and rely on data. Having Lambda at least tells you you have/have had a burnable mixture at 7K+
There is definitely a burnable mixture at 7000rpm, it was setup on the dyno with the relevant instrumentation needed. But I'll fit the lambda probe to confirm it's still 100% and get reliable data.
Toyotec, could you please help with more specific specifications to the mods that you have recommended. What cam would you recommend? To what value should the compression ratio be raised? The highest readily available pump gas here is 95 ULP.
Got myself an Estas 282 hydro cam and a spare cylinder head. The plan is to skim the head to raise the compression and have some porting and gasflow done to it. Also thinking of installing some uprated valve springs, Will be pulling the current head to cc the motor to determine actual compression ratio. VW claims 10:1 on this motor. Will be running the motor on 95 octane, what compression ratio would be recommended? Also thinking of installing some uprated valve springs, would it help or not really necessary?
