Aftermarket ECUs
Discussion
trev4 said:
Well after a visit to Mat Smith this morning It looks like my preferred option of going for the Gems system is out of the running as I don't have a block that could be cross bolted, apparently the 4.5s and later 5lt cars should be ok, so it's back to the usual suspects for my 4lt
So the above information is not 100% reliable then, Matt Smith has not confirmed that the GEMS installation will not fit all the RV8 engine variants?I too am looking at purchasing a new ECU and harness, and don't want to get this wrong, as the GEMS is an excellent system and a popular choice, with Mark Adams as one of the best options for the installation.
Edited by portzi on Sunday 16th July 06:22
Im assuming mat smith is referring to the blocks having the bosses weather drilled n tapped or not for the knock sensors. Nothing to do with being cross bolted or not. Its just that the later blocks that are cross bolted would also have these bosses on the sides.
Im sure there must be a way of fitting the knock sensors to the earlier blocks.
Im sure there must be a way of fitting the knock sensors to the earlier blocks.
Although the RV isn't known to be a noisy engine it does have its mechanical noises though so getting knock sensors to detect knock rather than something normal is the art.
I'm assuming these knock sensors allow you to advance spark to almost danger levels thus using the sensors to retard and keep engine safe. but detecting knock just means you've advanced it to far, knock must mean detonation at the wrong time so why would you even go there.
I think there's more power in my engine but Mbe keeps it safe and away from the danger area, even flat out. That's surely a good thing.
Gems by how I read it suggests knock sensors will control these parimeters rather than the mapping and spark control of the installer and mapper.
One sensor going down or not reacting to small pinking is going to lead to disaster,,, or have I understood it wrong and is that not actually a concern.
I also assume the latest blocks are more robust with cross bolting etc so most suited to applying knock sensors.
If I was thinking of this install I'd be reading up on knock sensors rather seriously as it appears you'll be relying on them to save your engine self detonating.
As usual I'm happy for the more informed to pull this post apart if it's inaccurate or simply ignorant. Just remember I'm not a mechanic
I'm assuming these knock sensors allow you to advance spark to almost danger levels thus using the sensors to retard and keep engine safe. but detecting knock just means you've advanced it to far, knock must mean detonation at the wrong time so why would you even go there.
I think there's more power in my engine but Mbe keeps it safe and away from the danger area, even flat out. That's surely a good thing.
Gems by how I read it suggests knock sensors will control these parimeters rather than the mapping and spark control of the installer and mapper.
One sensor going down or not reacting to small pinking is going to lead to disaster,,, or have I understood it wrong and is that not actually a concern.
I also assume the latest blocks are more robust with cross bolting etc so most suited to applying knock sensors.
If I was thinking of this install I'd be reading up on knock sensors rather seriously as it appears you'll be relying on them to save your engine self detonating.
As usual I'm happy for the more informed to pull this post apart if it's inaccurate or simply ignorant. Just remember I'm not a mechanic
The cross bolted blocks have a rear mounting point for the sensor, the early blocks don't. So, if you plan to use a Gems flywheel you need a cross bolted block.
The trigger wheel pictured above won't work. The Gems trigger pattern is pretty unique hence why it's not an 'off the shelf' item. It has to be manufactured from a lump of metal as opposed to being something like pressed steel.
I have done a few for chevrolets and could do one for a tvr but it would need to be fitted very precisely to get accurate timing. You also need a cam sensor.
The trigger wheel pictured above won't work. The Gems trigger pattern is pretty unique hence why it's not an 'off the shelf' item. It has to be manufactured from a lump of metal as opposed to being something like pressed steel.
I have done a few for chevrolets and could do one for a tvr but it would need to be fitted very precisely to get accurate timing. You also need a cam sensor.
Boosted LS1 said:
The cross bolted blocks have a rear mounting point for the sensor, the early blocks don't. So, if you plan to use a Gems flywheel you need a cross bolted block.
The trigger wheel pictured above won't work. The Gems trigger pattern is pretty unique hence why it's not an 'off the shelf' item. It has to be manufactured from a lump of metal as opposed to being something like pressed steel.
I have done a few for chevrolets and could do one for a tvr but it would need to be fitted very precisely to get accurate timing. You also need a cam sensor.
This is as I understood it when speaking to Mark AdamsThe trigger wheel pictured above won't work. The Gems trigger pattern is pretty unique hence why it's not an 'off the shelf' item. It has to be manufactured from a lump of metal as opposed to being something like pressed steel.
I have done a few for chevrolets and could do one for a tvr but it would need to be fitted very precisely to get accurate timing. You also need a cam sensor.
portzi said:
trev4 said:
Well after a visit to Mat Smith this morning It looks like my preferred option of going for the Gems system is out of the running as I don't have a block that could be cross bolted, apparently the 4.5s and later 5lt cars should be ok, so it's back to the usual suspects for my 4lt
So the above information is not 100% reliable then, Matt Smith has not confirmed that the GEMS installation will not fit all the RV8 engine variants?I too am looking at purchasing a new ECU and harness, and don't want to get this wrong, as the GEMS is an excellent system and a popular choice, with Mark Adams as one of the best options for the installation.
Edited by portzi on Sunday 16th July 06:22
Classic Chim said:
More reading needed,,, but can anyone tell me how a knock sensor works.
Is it a sound detecting device of some desription.
Ta
Knock sensors detect vibration caused by noise. Modern engines are designed to run as lean as possible for emissions regs and for fuel economy. The leaner you go, the bigger the risk of detonation so the knock sensor is mounted in the centre of the block (on a 4 cylinder) and when/if detonation occurs, the vibration caused by the premature bang is detected. Instantly the ECU retards the ignition and advances it again once the problem has passed. This is all done almost instantly so you would never notice when driving. Is it a sound detecting device of some desription.
Ta
If a knock sensor fails the ECU will retard the ignition and you will end up in 'limp mode'. The car will still drive but will feel very flat and unresponsive. The engine management light will come on to warn you of a problem.
Its all part of manufacturers striving to get the absolute limit from each squirt of fuel.
With a diagnostic tester connected and in the 'live data' menu, and the knock sensor showing on the screen, a very simple test is to tap the block near the sensor with a hammer. The reading will change to show its working. This is only a basic test but may prove if its working.
Edited by N7GTX on Sunday 16th July 11:53
Classic Chim said:
Although the RV isn't known to be a noisy engine it does have its mechanical noises though so getting knock sensors to detect knock rather than something normal is the art.
I'm assuming these knock sensors allow you to advance spark to almost danger levels thus using the sensors to retard and keep engine safe. but detecting knock just means you've advanced it to far, knock must mean detonation at the wrong time so why would you even go there.
I think there's more power in my engine but Mbe keeps it safe and away from the danger area, even flat out. That's surely a good thing.
Gems by how I read it suggests knock sensors will control these parimeters rather than the mapping and spark control of the installer and mapper.
One sensor going down or not reacting to small pinking is going to lead to disaster,,, or have I understood it wrong and is that not actually a concern.
I also assume the latest blocks are more robust with cross bolting etc so most suited to applying knock sensors.
If I was thinking of this install I'd be reading up on knock sensors rather seriously as it appears you'll be relying on them to save your engine self detonating.
As usual I'm happy for the more informed to pull this post apart if it's inaccurate or simply ignorant. Just remember I'm not a mechanic
Quite the opposite, GEMS will only use the knock sensors to push the tuning of the engine to its optimum - if it detects any fraction of a knock, it will retard before any damage is done. If the knock sensor is not funtioning correctly then it will scale the ignition back to known safe levels and flash up a warning light. Through OBD you can then check the fault codes and will tell you exactly which sensor is not functioning correctly so you can go straight to the issue to see what's up.I'm assuming these knock sensors allow you to advance spark to almost danger levels thus using the sensors to retard and keep engine safe. but detecting knock just means you've advanced it to far, knock must mean detonation at the wrong time so why would you even go there.
I think there's more power in my engine but Mbe keeps it safe and away from the danger area, even flat out. That's surely a good thing.
Gems by how I read it suggests knock sensors will control these parimeters rather than the mapping and spark control of the installer and mapper.
One sensor going down or not reacting to small pinking is going to lead to disaster,,, or have I understood it wrong and is that not actually a concern.
I also assume the latest blocks are more robust with cross bolting etc so most suited to applying knock sensors.
If I was thinking of this install I'd be reading up on knock sensors rather seriously as it appears you'll be relying on them to save your engine self detonating.
As usual I'm happy for the more informed to pull this post apart if it's inaccurate or simply ignorant. Just remember I'm not a mechanic
One big point with knock though is that it is very hard to detect accurately, and different cylinders will sound differently to the sensor when they knock depending how the vibration propogates through the block. For this reason, when OEM ECUs are developed, lots of (sacrificial) engines will be pushed to knock on each specific cylinder so that the fequencies can be precisely measued for that specific sensor listening position, so that the ECU knows exactly what it's looking for to be able to react quickly. This relies on the sensor being in the same place; on later cross-bolted blocks, the sensor bosses are pre-existing - so there are threaded holes already in the correct place so you just need to bolt the sensors on and you're good to go. With earlier blocks, I've heard that the lump is in the casting, but there is no hole drilled or tapped - but I may be wrong. If it isn't then this block can't be used, as you can't just bolt the sensors on anywhere as they will not hear any knock in the same way as the ECU is expecting.
The issue with aftermarket ECUs is that the fine details of the knock frequency for each cylinder are not likely to be as well defined, as they won't have conducted the same level of testing with sacrificial engines to have the data available, so the limits will be a little more generic. So the protection may still be there, but it may not pick up knock as quickly or accurately so you would want it to be a last resort rather than a regular contributer to the map.
So the cross bolted thing as boostedLS1 says is purely due to having the knock sensor bosses, and the crank trigger mount which are features of the casting of the later model blocks, so not something that can be added easily.
Sorry for intruding but I'd like to ask a question regarding management systems.
How can a twin air flow meter induction system be made to work properly with a mot catalytic emissions system.
My car is ancient compared to what I've tried to read and understand with a distributor still
. It's a 95 griff 500 with original management system.
Cheers fellas
How can a twin air flow meter induction system be made to work properly with a mot catalytic emissions system.
My car is ancient compared to what I've tried to read and understand with a distributor still
. It's a 95 griff 500 with original management system.Cheers fellas
450Nick said:
Quite the opposite, GEMS will only use the knock sensors to push the tuning of the engine to its optimum - if it detects any fraction of a knock, it will retard before any damage is done. If the knock sensor is not funtioning correctly then it will scale the ignition back to known safe levels and flash up a warning light. Through OBD you can then check the fault codes and will tell you exactly which sensor is not functioning correctly so you can go straight to the issue to see what's up.
One big point with knock though is that it is very hard to detect accurately, and different cylinders will sound differently to the sensor when they knock depending how the vibration propogates through the block. For this reason, when OEM ECUs are developed, lots of (sacrificial) engines will be pushed to knock on each specific cylinder so that the fequencies can be precisely measued for that specific sensor listening position, so that the ECU knows exactly what it's looking for to be able to react quickly. This relies on the sensor being in the same place; on later cross-bolted blocks, the sensor bosses are pre-existing - so there are threaded holes already in the correct place so you just need to bolt the sensors on and you're good to go. With earlier blocks, I've heard that the lump is in the casting, but there is no hole drilled or tapped - but I may be wrong. If it isn't then this block can't be used, as you can't just bolt the sensors on anywhere as they will not hear any knock in the same way as the ECU is expecting.
The issue with aftermarket ECUs is that the fine details of the knock frequency for each cylinder are not likely to be as well defined, as they won't have conducted the same level of testing with sacrificial engines to have the data available, so the limits will be a little more generic. So the protection may still be there, but it may not pick up knock as quickly or accurately so you would want it to be a last resort rather than a regular contributer to the map.
So the cross bolted thing as boostedLS1 says is purely due to having the knock sensor bosses, and the crank trigger mount which are features of the casting of the later model blocks, so not something that can be added easily.
Thanks Nick. Hopefully others will gain something from your answer from my ignorant questions! One big point with knock though is that it is very hard to detect accurately, and different cylinders will sound differently to the sensor when they knock depending how the vibration propogates through the block. For this reason, when OEM ECUs are developed, lots of (sacrificial) engines will be pushed to knock on each specific cylinder so that the fequencies can be precisely measued for that specific sensor listening position, so that the ECU knows exactly what it's looking for to be able to react quickly. This relies on the sensor being in the same place; on later cross-bolted blocks, the sensor bosses are pre-existing - so there are threaded holes already in the correct place so you just need to bolt the sensors on and you're good to go. With earlier blocks, I've heard that the lump is in the casting, but there is no hole drilled or tapped - but I may be wrong. If it isn't then this block can't be used, as you can't just bolt the sensors on anywhere as they will not hear any knock in the same way as the ECU is expecting.
The issue with aftermarket ECUs is that the fine details of the knock frequency for each cylinder are not likely to be as well defined, as they won't have conducted the same level of testing with sacrificial engines to have the data available, so the limits will be a little more generic. So the protection may still be there, but it may not pick up knock as quickly or accurately so you would want it to be a last resort rather than a regular contributer to the map.
So the cross bolted thing as boostedLS1 says is purely due to having the knock sensor bosses, and the crank trigger mount which are features of the casting of the later model blocks, so not something that can be added easily.
Knock sensors damn good things.
Am I right thinking Gems and LR already have extensive testing of these very knock sensors in 4.6 blocks so if fitted into the original boss on those blocks should pick up the correct sound frequencies as knock.
This is allowing the best map with these knock sensors acting as (ears) to stop you going to far. Great idea.
Classic Chim said:
Thanks Nick. Hopefully others will gain something from your answer from my ignorant questions!
Knock sensors damn good things.
Am I right thinking Gems and LR already have extensive testing of these very knock sensors in 4.6 blocks so if fitted into the original boss on those blocks should pick up the correct sound frequencies as knock.
This is allowing the best map with these knock sensors acting as (ears) to stop you going to far. Great idea.
That's exactly right, you're leveraging all of the good work done by LR by using the same ECU with the same sensors in the correct positions, so its essentially an OEM installation.Knock sensors damn good things.
Am I right thinking Gems and LR already have extensive testing of these very knock sensors in 4.6 blocks so if fitted into the original boss on those blocks should pick up the correct sound frequencies as knock.
This is allowing the best map with these knock sensors acting as (ears) to stop you going to far. Great idea.
mk1fan said:
SILICONEKID 345HP 12.03 said:
I think a knock sensor is a microphone
Are people going crazy about Gems because they are fully Sequential ?
Why not have a look at a Range Rover with Gems and it will answer all these questions .
If you can get a copy, have a read of the Sprint article.Are people going crazy about Gems because they are fully Sequential ?
Why not have a look at a Range Rover with Gems and it will answer all these questions .
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