Standalone ECU Monitor
25 March 2003, 10:21 PM
#211
Scooby Regular
Actually - both the DIY and commercial monitors wouldn't read the boost readings (or any other, for that matter) correctly from the Apexi Power FC - remember, the Power FC is a replacement ECU, and as such, the data/code layout is completely different from the standard ECU.
I've managed to get hold of the communications protocol's for the Power FC, I just need to get around to writing some software for it !
Might make a start tomorrow....
[Edited by BoxerFlat4 - 3/25/2003 10:21:58 PM]
I've managed to get hold of the communications protocol's for the Power FC, I just need to get around to writing some software for it !
Might make a start tomorrow....[Edited by BoxerFlat4 - 3/25/2003 10:21:58 PM]
26 March 2003, 10:35 AM
#214
Scooby Regular
iTrader: (1)
Join Date: Oct 2002
Location: London
Posts: 553
Likes: 0
Received 0 Likes
on
0 Posts
I don't know if this is of any help but I do a lot of work with LCD displays for computers, I swear by Matrix Orbital displays,
lots of clever LCD and RS232 guys available here
http://www.lcdforums.com/forums/view...hp?forum=2&188
just a thought
lots of clever LCD and RS232 guys available here
http://www.lcdforums.com/forums/view...hp?forum=2&188
just a thought
26 March 2003, 10:37 AM
#215
Scooby Regular
Join Date: Aug 2002
Posts: 61
Likes: 0
Received 0 Likes
on
0 Posts
Ah, its good to see this thread happening again.
My little device (for the MY98) is working a treat. Well, except for the fact that I just blew up the Mega8 chip and have to get another one. Its still not (completely) finished yet as, unfortunately, I just don’t have the time to spend on this as I would like. But saying that, I’m planning to call it quits pretty soon with the Sub ECU as I have had an Apexi PowerFC sitting around for 4 months now doing nothing whilst I mucked around with this.
I can confirm that the Subaru Select Protocol (and hence the diagnostic plug) does NOT operate with the PowerFC. It would be nice if aftermarket ECUs did support the diagnostic protocols but I knew it was a long shot hoping that they would. Before 9? (not to sure of the exact year) all car manufacturers had their own diagnostic communication protocol and equipment. The introduction of ODB-II (On Board Diagnostics V2) required all vehicles in America to subscribe to a common diagnostics protocol (and hence equipment). Henceforth, if vehicles were being produced for the US market ODB-II was required in the ECU. I don’t know whether other countries have specified ODB-II as a regulation, but it appears that vehicles in other countries are ODB-II compliant after a certain build date. Anyway, where was I? The point I was going to make was that it would be fantastic if aftermarket ECUs also supported ODB-II but it looks like they don’t have to as, technically, they are immune from the rules as these ECUs are meant for ‘off road use’- i.e. racing. Therefore exempt from certain emission requirements also. Bottom line, the ECU Monitor as discussed in this thread will not work with the PowerFC.
Right, I am undecided about stage 2 for myself. The options are:
1. Develop a similar thing for the PowerFC
2. Bypass the ECU entirely and hook straight into the analogue signals prior to the ECU and map these
Option 1:
Why:
Would be a good learning experience (I’m a Mech Eng trying to get more micro-electronics experience) for me plus would remove the hassle of determining the relationship between the analogue signal and its related measurement.
Problems:
Sussing out the communication and getting it to work. I have been collecting a bit of info regarding the PowerFC communication protocol and know a bit about it already as well as the wiring of the plug. Our good old Japanese friend which provided much of the information that has allowed people to play with the Subaru ECU has also done a similar thing with the PowerFC. Problem is that it is in Japanese and I’m still trying to get a real feel for how the comms are handled (Im sure if I could understand Japanese I would be having no problems as there is a wealth of info out there about the PowerFC in Japanese). So that could take a while. It can be done as a New Zealand based ‘company’ offers such a thing (for data logging) in partnership with a mystery technical collaborator (I assume our Japanese friend). But the software is not cheap.
Option 2:
Why:
Again a good learning experience. Negates the ECU type issue – i.e. everyone with a Subaru could use one. I race rally cars and this would allow me to build a similar thing for it. Much faster data-acquisition for datalogging (more samples per second).
Problems:
I don’t have any experience with using micro-controllers to perform analogue to digital conversions and all the problems associate with such. But, luckily, I am surrounded by lots of other Mech, Elec, Soft engineers at work that do. So, problems I encounter may be solvable with some of their help. Determining the analogue signal to parameter relationship – wont be much fun (but will be do-able). I am also willing to bet that different sensors (and hence relationships) have been utilised in the WRX over the model years.
Anyway, that’s where I am at. I am heading towards option 2 due to its compatibility with other vehicles -but I would also like to ‘conquer’ the challenge of doing it with the PowerFC.
I was thinking I could put a list of links and other info that I have found regarding the PowerFC in a new thread if anyone is interested and feels like adding to it. If you would like me to do this, let me know.
Also, if other people are interested in option 2, let me know and when I get around to starting I will start a new thread and hopefully we can nut it out as a group.
Adam
[Edited by AJKS - 3/26/2003 11:41:50 AM]
My little device (for the MY98) is working a treat. Well, except for the fact that I just blew up the Mega8 chip and have to get another one. Its still not (completely) finished yet as, unfortunately, I just don’t have the time to spend on this as I would like. But saying that, I’m planning to call it quits pretty soon with the Sub ECU as I have had an Apexi PowerFC sitting around for 4 months now doing nothing whilst I mucked around with this.
I can confirm that the Subaru Select Protocol (and hence the diagnostic plug) does NOT operate with the PowerFC. It would be nice if aftermarket ECUs did support the diagnostic protocols but I knew it was a long shot hoping that they would. Before 9? (not to sure of the exact year) all car manufacturers had their own diagnostic communication protocol and equipment. The introduction of ODB-II (On Board Diagnostics V2) required all vehicles in America to subscribe to a common diagnostics protocol (and hence equipment). Henceforth, if vehicles were being produced for the US market ODB-II was required in the ECU. I don’t know whether other countries have specified ODB-II as a regulation, but it appears that vehicles in other countries are ODB-II compliant after a certain build date. Anyway, where was I? The point I was going to make was that it would be fantastic if aftermarket ECUs also supported ODB-II but it looks like they don’t have to as, technically, they are immune from the rules as these ECUs are meant for ‘off road use’- i.e. racing. Therefore exempt from certain emission requirements also. Bottom line, the ECU Monitor as discussed in this thread will not work with the PowerFC.
Right, I am undecided about stage 2 for myself. The options are:
1. Develop a similar thing for the PowerFC
2. Bypass the ECU entirely and hook straight into the analogue signals prior to the ECU and map these
Option 1:
Why:
Would be a good learning experience (I’m a Mech Eng trying to get more micro-electronics experience) for me plus would remove the hassle of determining the relationship between the analogue signal and its related measurement.
Problems:
Sussing out the communication and getting it to work. I have been collecting a bit of info regarding the PowerFC communication protocol and know a bit about it already as well as the wiring of the plug. Our good old Japanese friend which provided much of the information that has allowed people to play with the Subaru ECU has also done a similar thing with the PowerFC. Problem is that it is in Japanese and I’m still trying to get a real feel for how the comms are handled (Im sure if I could understand Japanese I would be having no problems as there is a wealth of info out there about the PowerFC in Japanese). So that could take a while. It can be done as a New Zealand based ‘company’ offers such a thing (for data logging) in partnership with a mystery technical collaborator (I assume our Japanese friend). But the software is not cheap.
Option 2:
Why:
Again a good learning experience. Negates the ECU type issue – i.e. everyone with a Subaru could use one. I race rally cars and this would allow me to build a similar thing for it. Much faster data-acquisition for datalogging (more samples per second).
Problems:
I don’t have any experience with using micro-controllers to perform analogue to digital conversions and all the problems associate with such. But, luckily, I am surrounded by lots of other Mech, Elec, Soft engineers at work that do. So, problems I encounter may be solvable with some of their help. Determining the analogue signal to parameter relationship – wont be much fun (but will be do-able). I am also willing to bet that different sensors (and hence relationships) have been utilised in the WRX over the model years.
Anyway, that’s where I am at. I am heading towards option 2 due to its compatibility with other vehicles -but I would also like to ‘conquer’ the challenge of doing it with the PowerFC.
I was thinking I could put a list of links and other info that I have found regarding the PowerFC in a new thread if anyone is interested and feels like adding to it. If you would like me to do this, let me know.
Also, if other people are interested in option 2, let me know and when I get around to starting I will start a new thread and hopefully we can nut it out as a group.
Adam
[Edited by AJKS - 3/26/2003 11:41:50 AM]
26 March 2003, 10:45 AM
#216
Scooby Regular
Join Date: Aug 2002
Posts: 61
Likes: 0
Received 0 Likes
on
0 Posts
Also, if you haven't been there for a while, AndrewC has been adding extra stuff to his website every so often. Especially useful if you are 'scared' of jumping in alone (ie added a bit more info about programming with Bascom-AVR).
Adam
Adam
26 March 2003, 11:02 AM
#218
Scooby Regular
Join Date: Aug 2002
Posts: 61
Likes: 0
Received 0 Likes
on
0 Posts
Oh yeh, one more thing! If I go with option 2, then there is another lovely little add on for the project:
Stepper motor driven 'analogue' gauges! All the Defi, HKS, Apexi, (read expensive) 'analogue' gauges are in fact digitally driven gauges. All the analogue signal that are to be monitored are passed into a central control box (which can handle 5 or so different inputs and outputs – the outputs being the gauges). This box converts the analogue signal to a digital signal and then uses that as an input for controlling stepper motors (I assume they are either stepper or servo motors) inside the gauge. In other words, all the gauges would be identical expect for the text and markings displaying what was being measured. There would be no 'smarts' inside the gauge, just a motor and hardware. All the smarts is controlled by the central control unit.
See where I am going with this? If we are already building a box to take inputs from all the useful analogue signals and convert them into digital data, it wont take much more effort to also build in the extra electronics required to drive a number of stepper motors. Driving stepper motors with micro-controllers is a standard thing and there is plenty of info on the web about it - even examples for the Atmel chips and Bascom-AVR. The hardware side of things are simple, the stepper motors would cost around AU$50 (GBP20). The problem would be making them look 'pretty' ala the Defi units. One of my mates at work is a industrial designer who also races cars and is keen to do this project and can make us up some 'professional' looking gauge faces - but if you dont have access to such a great (and useful!) mate Im not to sure how you would overcome this. Actually, someone did mention to me that they had to re-calibrate their gauge once and just used a high quality inkjet printer and it apparently worked great. So there is an option.
Why bother doing this when you already have the info displayed digitally on an LCD? Because you can! Plus, I don’t mind looking at temp’s on an LCD but some information (i.e. boost) is best conveyed with analogue gauges.
Anyway, just an extra option to consider.
Adam
[Edited by AJKS - 3/26/2003 11:07:39 AM]
Stepper motor driven 'analogue' gauges! All the Defi, HKS, Apexi, (read expensive) 'analogue' gauges are in fact digitally driven gauges. All the analogue signal that are to be monitored are passed into a central control box (which can handle 5 or so different inputs and outputs – the outputs being the gauges). This box converts the analogue signal to a digital signal and then uses that as an input for controlling stepper motors (I assume they are either stepper or servo motors) inside the gauge. In other words, all the gauges would be identical expect for the text and markings displaying what was being measured. There would be no 'smarts' inside the gauge, just a motor and hardware. All the smarts is controlled by the central control unit.
See where I am going with this? If we are already building a box to take inputs from all the useful analogue signals and convert them into digital data, it wont take much more effort to also build in the extra electronics required to drive a number of stepper motors. Driving stepper motors with micro-controllers is a standard thing and there is plenty of info on the web about it - even examples for the Atmel chips and Bascom-AVR. The hardware side of things are simple, the stepper motors would cost around AU$50 (GBP20). The problem would be making them look 'pretty' ala the Defi units. One of my mates at work is a industrial designer who also races cars and is keen to do this project and can make us up some 'professional' looking gauge faces - but if you dont have access to such a great (and useful!) mate Im not to sure how you would overcome this. Actually, someone did mention to me that they had to re-calibrate their gauge once and just used a high quality inkjet printer and it apparently worked great. So there is an option.
Why bother doing this when you already have the info displayed digitally on an LCD? Because you can! Plus, I don’t mind looking at temp’s on an LCD but some information (i.e. boost) is best conveyed with analogue gauges.
Anyway, just an extra option to consider.
Adam
[Edited by AJKS - 3/26/2003 11:07:39 AM]
26 March 2003, 11:03 AM
#219
Scooby Regular
OBD communications protocol won't work with pre 97 cars : I (believe) MY97 cars on support the OBD protocol. Just so you know, this is why people like AndrewC and the PSI3 people have problems with the pre97 cars, because you have to use a specific Subaru diagnostic protocol to talk to the ECU, and it's not very fast. Or documentated, for that matter.
Just be aware, although I plan on starting work on the Apexi Power FC software soon, I do have other things on my list (write a web shop, run a business, etc etc), so it won't be ready and working next week !
Just be aware, although I plan on starting work on the Apexi Power FC software soon, I do have other things on my list (write a web shop, run a business, etc etc), so it won't be ready and working next week !
26 March 2003, 11:08 AM
#220
Scooby Regular
AJKS (Adam) -
Can you send me your e-mail, as I think you'd be an interesting addition to the ImprezECU Yahoo group that I moderate : there's alot of interesting work going on inside, and I can subscribe you if you like.
Paul.Houbart@TheGecko.biz
BTW - I'm a fellow Oz, still missing the homeland !
Can you send me your e-mail, as I think you'd be an interesting addition to the ImprezECU Yahoo group that I moderate : there's alot of interesting work going on inside, and I can subscribe you if you like.
Paul.Houbart@TheGecko.biz
BTW - I'm a fellow Oz, still missing the homeland !
26 March 2003, 11:16 AM
#221
Scooby Regular
Join Date: Aug 2002
Posts: 61
Likes: 0
Received 0 Likes
on
0 Posts
Paul,
Were you thinking along the 'open source' lines or more of a commerical venture?
If it is open source, I would be much interested in hearing what you know about the PowerFC comms when you have time. I understand what its like to be time poor yet idea rich! I started mucking around with this when Andrew first mentioned it and am in no hurry (only because I dont have the time I would like to devote). I would assume, being a Apexi PowerFC dealer (as well as PSI3) you might some access to some good info ;-)
Anyway, all in good time.
Adam
Were you thinking along the 'open source' lines or more of a commerical venture?
If it is open source, I would be much interested in hearing what you know about the PowerFC comms when you have time. I understand what its like to be time poor yet idea rich! I started mucking around with this when Andrew first mentioned it and am in no hurry (only because I dont have the time I would like to devote). I would assume, being a Apexi PowerFC dealer (as well as PSI3) you might some access to some good info ;-)
Anyway, all in good time.
Adam
26 March 2003, 11:37 AM
#223
Scooby Regular
Join Date: Aug 2002
Posts: 61
Likes: 0
Received 0 Likes
on
0 Posts
willgill,
Im probably not the best to answer the car compatibility issue thingy. But, nether-the-less, Andrew's code setup can not be used on post MY98 as it is based on the Subaru Select Protocol communication code (MY98 and earlier used a proprietary Subaru communication protocol that the later cars do not support). So therefore, yes, 95 models ‘can’ use this, but… The but being that Andrews (and my) code is based on asking the ECU to provide a lot of parameters back each time a request is sent. This is NOT supported by earlier ECU’s (its one parameter per request only). It doesn’t mean that YOU cant get it to work as it is possible. But, Andrews code and schematic available on his site will not work on your ECU without modification to the code – you’ll need to develop the code a bit yourself. There was a whole other thread created (started by Pavlo) http://www.scoobynet.co.uk/bbs/thread.asp?ThreadID=119754 titled “DIY ECU remap project” that discusses this a bit (from memory) – as they were extracting all the maps of the earlier ECUs this way.
Hope this helps a little,
adam
Im probably not the best to answer the car compatibility issue thingy. But, nether-the-less, Andrew's code setup can not be used on post MY98 as it is based on the Subaru Select Protocol communication code (MY98 and earlier used a proprietary Subaru communication protocol that the later cars do not support). So therefore, yes, 95 models ‘can’ use this, but… The but being that Andrews (and my) code is based on asking the ECU to provide a lot of parameters back each time a request is sent. This is NOT supported by earlier ECU’s (its one parameter per request only). It doesn’t mean that YOU cant get it to work as it is possible. But, Andrews code and schematic available on his site will not work on your ECU without modification to the code – you’ll need to develop the code a bit yourself. There was a whole other thread created (started by Pavlo) http://www.scoobynet.co.uk/bbs/thread.asp?ThreadID=119754 titled “DIY ECU remap project” that discusses this a bit (from memory) – as they were extracting all the maps of the earlier ECUs this way.
Hope this helps a little,
adam
26 March 2003, 11:51 AM
#224
Scooby Regular
Thread Starter
Join Date: Jul 2000
Location: Lancashire
Posts: 2,209
Likes: 0
Received 0 Likes
on
0 Posts
Paul: No classic shape Scoob (ie Pre-MY01) is OBD compatible (with the possible exception of some US models).
The protocol for pre-97 is the same as 97-98 with 1 limitation, I just haven't had the time to covert the code to work within this limitation.
Adam: I though you were already in the mailgroup?
I have a million-and-one ideas for projects, just haven't got the time to build them
There has been quite a lot of traffic on the Bascom mailgroup recently about blowing the RST pin on AT chips, for anyone using the Sample Electronics programmer cable it may be worth reading Atmel Appnote AVR040 and the comments on the subject in the Bascom manual. Personally I have only ever destroyed 1 chip and that was my fault.
Andrew...
The protocol for pre-97 is the same as 97-98 with 1 limitation, I just haven't had the time to covert the code to work within this limitation.
Adam: I though you were already in the mailgroup?
I have a million-and-one ideas for projects, just haven't got the time to build them
There has been quite a lot of traffic on the Bascom mailgroup recently about blowing the RST pin on AT chips, for anyone using the Sample Electronics programmer cable it may be worth reading Atmel Appnote AVR040 and the comments on the subject in the Bascom manual. Personally I have only ever destroyed 1 chip and that was my fault.
Andrew...
26 March 2003, 11:58 AM
#225
Scooby Regular
Join Date: Aug 2002
Posts: 61
Likes: 0
Received 0 Likes
on
0 Posts
Adam: I though you were already in the mailgroup?
Re blowing up chips. Yeh, read that. I blew mine because my voltage reg lost its earth and then (it appears) provided the chip with 12V. Oops. Live and learn...
Adam
26 March 2003, 12:35 PM
#226
Scooby Regular
Right, he's a member.
AndrewC - I knew as I was typing about the OBD situation I had it slightly wrong, but couldn't be ar!!d to figure out why. Dangers of engaging fingers before brain, I suppose...
AndrewC - I knew as I was typing about the OBD situation I had it slightly wrong, but couldn't be ar!!d to figure out why. Dangers of engaging fingers before brain, I suppose...
26 March 2003, 12:53 PM
#227
Scooby Regular
Join Date: Feb 2002
Location: oustide the asylum?
Posts: 3,306
Likes: 0
Received 0 Likes
on
0 Posts
The protocol for pre-97 is the same as 97-98 with 1 limitation
I have a million-and-one ideas for projects, just haven't got the time to build them
Sometimes I hate having to work!
26 March 2003, 01:04 PM
#228
Scooby Regular
I've solved this in software on a PC, but not coded it into an AVR chip yet.
26 March 2003, 01:10 PM
#229
Scooby Regular
Join Date: Feb 2002
Location: oustide the asylum?
Posts: 3,306
Likes: 0
Received 0 Likes
on
0 Posts
It's on the group. You're welcome to have a look & a play - I'd prefer it to keep the distribution down until it's finished though.
[Edited by dnb - 3/26/2003 1:15:03 PM]
[Edited by dnb - 3/26/2003 1:15:03 PM]
26 March 2003, 08:03 PM
#231
Scooby Regular
Join Date: Dec 2001
Posts: 3,418
Likes: 0
Received 0 Likes
on
0 Posts
I am working with motorolla processors at work at the moment..
Number of different boards for a number of different applications..
Current product has 12 boards with errrmmm 15 processors...
Thinking really I should put my mind to creating a new ECU... with a display output etc..
Wonder if work would miss a couple of boards?
Number of different boards for a number of different applications..
Current product has 12 boards with errrmmm 15 processors...
Thinking really I should put my mind to creating a new ECU... with a display output etc..
Wonder if work would miss a couple of boards?
01 April 2003, 05:03 PM
#233
Scooby Regular
iTrader: (2)
Join Date: Jan 2003
Location: Lofty in Hull
Posts: 1,587
Likes: 0
Received 0 Likes
on
0 Posts
OK guys, I am strictly non-techie and I've lost the thread of which MY's this wonderful gadget is suitable for.
I have an MY00 - will it work on my car??
If not, I have a mate who is an electronics wizard (professionally) - what needs to be done to get it to work on an MY00??
I have an MY00 - will it work on my car??
If not, I have a mate who is an electronics wizard (professionally) - what needs to be done to get it to work on an MY00??
01 April 2003, 06:34 PM
#234
Scooby Regular
Join Date: Feb 2003
Location: Zed Ess Won Hay Tee
Posts: 21,611
Likes: 0
Received 0 Likes
on
0 Posts
i really really want one of these, but dont have a clue about making them or if there suitible lol
how much are we looking for, to physicaly have one built up to fit in me car??
my97wrx
how much are we looking for, to physicaly have one built up to fit in me car??
my97wrx
02 April 2003, 01:40 AM
#235
Scooby Regular
Join Date: Aug 2002
Posts: 61
Likes: 0
Received 0 Likes
on
0 Posts
Guys,
Its meant for a MY97/98. Refer:
http://www.scoobymonitor.co.uk/
This is the website setup by AndrewC - the person who kicked it all off. Its meant as a DIY job - a lot of info is on Andrew site re the DIY bit.
It will not work on an MY00. The electronics wont be a problem but the software communication protocol with the ECU is - it is different.
Adam
Its meant for a MY97/98. Refer:
http://www.scoobymonitor.co.uk/
This is the website setup by AndrewC - the person who kicked it all off. Its meant as a DIY job - a lot of info is on Andrew site re the DIY bit.
It will not work on an MY00. The electronics wont be a problem but the software communication protocol with the ECU is - it is different.
Adam
17 May 2003, 02:37 PM
#236
Scooby Regular
Join Date: Aug 2002
Posts: 61
Likes: 0
Received 0 Likes
on
0 Posts
So, whats going on? Its been pretty quiet in here lately...
7 months later and Im still mucking around adding extra little things to the code but its working fine. If I get my act together I will post some pictures of my setup next week.
Who else actually built this and got it working?
adam
7 months later and Im still mucking around adding extra little things to the code but its working fine. If I get my act together I will post some pictures of my setup next week.
Who else actually built this and got it working?
adam
17 May 2003, 08:25 PM
#237
Scooby Regular
Thread Starter
Join Date: Jul 2000
Location: Lancashire
Posts: 2,209
Likes: 0
Received 0 Likes
on
0 Posts
I've put a few more photos on my website recently, in the 'Picture Gallery', I'll also post up any photos from anyone else who has built/installed one, just email them to me.
Andrew...
19 May 2003, 08:52 PM
#238
Scooby Newbie
Join Date: May 2003
Posts: 26
Likes: 0
Received 0 Likes
on
0 Posts
Guys,
Back on the early pages there was a lot of talk about knock sensing. Well this might help.
Most engine management systems look for knock in a "window" synchronized to the crankshaft. (As reported in the Bosch blue book)
The likely reason you are not seeing a "knock" parameter is that by hitting the engine block with a hammer you are not in teh correct "window" and also a hammer blow probably won't get pass the bandpass filter for engine noise.
Regards,
Mike Ede
PS if anyone has a nice silver turbo wagon for sale please let me know!!
Back on the early pages there was a lot of talk about knock sensing. Well this might help.
Most engine management systems look for knock in a "window" synchronized to the crankshaft. (As reported in the Bosch blue book)
The likely reason you are not seeing a "knock" parameter is that by hitting the engine block with a hammer you are not in teh correct "window" and also a hammer blow probably won't get pass the bandpass filter for engine noise.
Regards,
Mike Ede
PS if anyone has a nice silver turbo wagon for sale please let me know!!
20 May 2003, 01:03 AM
#240
Scooby Regular
Join Date: Feb 2003
Location: Zed Ess Won Hay Tee
Posts: 21,611
Likes: 0
Received 0 Likes
on
0 Posts
still following this
would like one of these, have been in touch with the man a few times about them
thinking about just buying a seperate set of guages and stuff now tho, any updates on the cost of a ready to build kit??
would like one of these, have been in touch with the man a few times about them
thinking about just buying a seperate set of guages and stuff now tho, any updates on the cost of a ready to build kit??