Speedometer Calibration
Discussion
I've noticed that my speedo is quite a bit out. I don't mind if reads fast, but that's not the case.
At an indicated 20mph its doing 30
At an indicated 30mph its doing 42
At an indicated 70mph its doing 85
The higher the speed the greater the error. I understand that this is an import so I am presuming that the Aussies have kph and not mph? Although what difference this makes I don't know!
So my questions to the knowledgeable:
1) Is there a pot that can be adjusted
2) Can I swap out another module of some kind?
3) Would a replacement clock sticker set be the answer if the wrong one had been fitted?
I am presuming that the car is running standard wheels and tyres but I have added a piccy for clarification.
All speeds were measured against my trusty GPS and also against a friend who was along side me with his so I am fairly confident of the error margin.
edited for Sunday typos!
At an indicated 20mph its doing 30
At an indicated 30mph its doing 42
At an indicated 70mph its doing 85
The higher the speed the greater the error. I understand that this is an import so I am presuming that the Aussies have kph and not mph? Although what difference this makes I don't know!
So my questions to the knowledgeable:
1) Is there a pot that can be adjusted
2) Can I swap out another module of some kind?
3) Would a replacement clock sticker set be the answer if the wrong one had been fitted?
I am presuming that the car is running standard wheels and tyres but I have added a piccy for clarification.
All speeds were measured against my trusty GPS and also against a friend who was along side me with his so I am fairly confident of the error margin.
edited for Sunday typos!
Edited by ss hsv on Sunday 24th September 11:11
I was thinking about that too. This car has really long legs 
I am told that there is a diff kit available which will bring sixth down and close up the other gears. This is something I would be interested in as sixth gear is an over-drive and could be a use-able gear.
I am not concerned about the fuel consumption as a trade off and guess I would need to get some info on this before fixing the speedo as it may be corrected automatically after the diff change ?
I am told that there is a diff kit available which will bring sixth down and close up the other gears. This is something I would be interested in as sixth gear is an over-drive and could be a use-able gear.
I am not concerned about the fuel consumption as a trade off and guess I would need to get some info on this before fixing the speedo as it may be corrected automatically after the diff change ?
as I understand it if the car has had modded diff then you could use the EFilive kit that ringram supplies to reprogram the ecu to take account of the change and correct the speedo. So you could buy your own - excellent value at the moment if you're not too scared to tinker with the settings yourself or book the car into LSV, Monkfish, Picador, Greens etc etc and have them do the work for you - and maybe get them to squeeze a few extra horses out while they're at it 
There are a couple of points to bear in mind.
First you need to check your gears are correct as mentioned. There is a built in calculator where you enter your diff ratio plus tyre size and the pcm speed output (and relevant pcm table values) is calculated ok. This sets the VSS OBDII logging PID which you can read while driving. (Assuming you are logging at the time).
You mess about with that until the PCM VSS speed matches road speed, usually with a GPS as was also mentioned.
The second part is to get the Speedo needle moving at the correct speed on the gauge as PCM output speed doesn't always match the display needle. (Usually needle reads a little more to save you going over the limit) This is a bit more interesting. Usually pick a speed, say 100kmph sit at the speed with your logging at 100 and your gps hopefully now also at 100 and see where the needle is. If the needle is 5% to high or low etc, then adjust H0105 but the relevant percentage. Ive forgotten which way you go, but its easy to change it the other way if you get it wrong the first time. Same principle for MPH, but most tables are in kmph by default. Conversion factor is 0.62M = 1Km
Tyre sizes do have an effect, I think last discussion it was calculated at around 2%, not enough to worry about really unless you have your own tune tool, then you can always be 100% bang on.
First you need to check your gears are correct as mentioned. There is a built in calculator where you enter your diff ratio plus tyre size and the pcm speed output (and relevant pcm table values) is calculated ok. This sets the VSS OBDII logging PID which you can read while driving. (Assuming you are logging at the time).
You mess about with that until the PCM VSS speed matches road speed, usually with a GPS as was also mentioned.
The second part is to get the Speedo needle moving at the correct speed on the gauge as PCM output speed doesn't always match the display needle. (Usually needle reads a little more to save you going over the limit) This is a bit more interesting. Usually pick a speed, say 100kmph sit at the speed with your logging at 100 and your gps hopefully now also at 100 and see where the needle is. If the needle is 5% to high or low etc, then adjust H0105 but the relevant percentage. Ive forgotten which way you go, but its easy to change it the other way if you get it wrong the first time. Same principle for MPH, but most tables are in kmph by default. Conversion factor is 0.62M = 1Km
Tyre sizes do have an effect, I think last discussion it was calculated at around 2%, not enough to worry about really unless you have your own tune tool, then you can always be 100% bang on.
Edited by ringram on Sunday 24th September 18:32
When Steve had the car he posted about repairing his speed convertor. I used to have the same problem with inaccurate speedo. I have replaced the converter with one you can calibrate. Things have moved on since the cars were imported and the convertors you can buy now are very accrate.
Better yet Duncan you can even tune it out with the H0105 table I mentioned, It basically just changes the signal from the PCM to the dash cluster the same as the programmable units, though those with tuning devices have access to this table without needing to cut wires and install something else. Just write to the table which is designed to change it and save yourself some money for a new camshaft or other.
Wow! Thanks for the replies guys.
I think this is the route I am going to go down. I am just about to order a FAST manifold so the mapping will need to be changed for this anyway. Also if I choose to go down the diff route, then I can simply mod the appropriate table afterwards
This was my initial question on the first post. I didn't realise that you can adjust the speedometer using the mapping software so I am going to have a go with that first, but thanks for the input I was hoping there was such a module. It's nice to have a choice!
Hey this is what I call progress. Not only have a managed to get answers to all the niggles, but it looks like you may also be able to help with my next quest - a cam I am going to add the FAST inlet manifold and a cam to go with it, but which one? I am looking for a streetable profile that has a fairly normal tickover and provides more midrange. I did the 8000 rpm screaming chevy in the Ultima, and it was not a nice car to drive in traffic or below 2500rpm. I have decided to put the blower on hold as to be honest, the power is 'almost' enough 
I am presuming that I have the standard throttle body, and that I should also be looking to take this upto 90mm at the same time to complete the breathing upgrade? I have in place the exhaust and the MAF bypass.
Sorry for all the questions guys, but please keep the answers coming, I really appreciate it
Well_Fans said:
as I understand it if the car has had modded diff then you could use the EFilive kit that ringram supplies to reprogram the ecu to take account of the change and correct the speedo. So you could buy your own - excellent value at the moment if you're not too scared to tinker with the settings yourself or book the car into LSV, Monkfish, Picador, Greens etc etc and have them do the work for you - and maybe get them to squeeze a few extra horses out while they're at it
I think this is the route I am going to go down. I am just about to order a FAST manifold so the mapping will need to be changed for this anyway. Also if I choose to go down the diff route, then I can simply mod the appropriate table afterwards
Island boy hsv said:
When Steve had the car he posted about repairing his speed convertor. I used to have the same problem with inaccurate speedo. I have replaced the converter with one you can calibrate. Things have moved on since the cars were imported and the convertors you can buy now are very accrate.
This was my initial question on the first post. I didn't realise that you can adjust the speedometer using the mapping software so I am going to have a go with that first, but thanks for the input I was hoping there was such a module. It's nice to have a choice!
ringram said:
Better yet Duncan you can even tune it out with the H0105 table I mentioned, It basically just changes the signal from the PCM to the dash cluster the same as the programmable units, though those with tuning devices have access to this table without needing to cut wires and install something else. Just write to the table which is designed to change it and save yourself some money for a new camshaft or other.
Hey this is what I call progress. Not only have a managed to get answers to all the niggles, but it looks like you may also be able to help with my next quest - a cam
I am going to add the FAST inlet manifold and a cam to go with it, but which one? I am looking for a streetable profile that has a fairly normal tickover and provides more midrange. I did the 8000 rpm screaming chevy in the Ultima, and it was not a nice car to drive in traffic or below 2500rpm. I have decided to put the blower on hold as to be honest, the power is 'almost' enough I am presuming that I have the standard throttle body, and that I should also be looking to take this upto 90mm at the same time to complete the breathing upgrade? I have in place the exhaust and the MAF bypass.
Sorry for all the questions guys, but please keep the answers coming, I really appreciate it
All the cars supplied by UK HSV have speed convertors fitted so if it's not working correctly you may need to take it out or your edits may not work as you expect. I have heard that need to be carefull using the EFI Live to edit PPM this could can kill the PCM? Maybe ringram can answer this?
Edited by Island boy hsv on Sunday 24th September 22:16
Hmm never heard of anything dying with efilive? Be interested to know where you saw something about it. Ive done well over 300 changes without any error and a mate in NZ is over 1000 and counting.
In fact I had one of the devices fitted by UK HSV in my GTS and it died like Steve's did. Steve resoldered his, I removed mine and just used efilive. I wrote it up here http://r8transformation.blogspot.com/ under the June 24th entry. Ive helped a couple of forum members change their tunes for SVA tests so I know it works for all models from 99 through to at least 2004.
SS HSV your idea sounds like a good plan. Im in 2 minds regarding intakes myself at present. Im off to Sema next month so thought I could get an intake at the same time. Only thing is that the FAST intake is an arse to get sealed there are loads of horror stories. Also the suggestion is to go for a Nick Williams or Holley 90mm throttle as the FAST sticks.. again horror stories.
However that all said other than the 8 tb manifolds that Harrop and some other ozzie guys make there isn't anything better that can supply more air.... except forced induction. (Im considering the 8 throttle body path mentioned as the ultimate solution).
If you are going down the cam route you are better to look at the heads first. Another potential quagmire.
There are now loads of excellent heads out there. I went with a set of Dart 205's as they were on an introductory special. The pair for $1300 US. The top of the line ones are Trickflow, ETP, and AFR, plus loads of aftermarket CNC ported 243 (LS6/LS2) heads. The ETP and TFS ones can be had with altered valve angles to increase intake. The Trickflow's flow something like 330cfm compared to stock LS1 of around 230, and stock LS2 of 270cfm.
What you want for a street NA engine is a small port with high flow. That keeps velocity up for intake enertia and helps keep the mixture turbulant. This makes for a better more consistent combustion charge less prone to detonation etc. Heads are around $2400 for a good set.
Then there is the cam.. Your nightmare has now truly begun. Terms like IVC, Overlap, LSA, Dynamic compression, quench as well as lifter and valve spring preloads etc will all be your enemy. Plus all the usual duration and lift info.
Mild cams are usually under 220 duration, with warm cams in the 220-230 range. Things get fairly heated after that. If you want max low down power stick with mid 220 and under.
Again the cam d'jour seems to be a comp cams XER lobe 224/228-112 with something like 0.590 lift. This will give excellent all round performance. Do a search on ls1tech for loads of info on it.
Ive yet to go for an mot sniff, but if emissions come into your cam choice then you will want to ensure minimal effective overlap. That means making sure you keep to 0 or less at 0.050. However that said with cats you can probably go a little lumpier. You can figure out overlap by (intake duration+exhaust duration/4)-LSA*2 In my case ((220+224/4) -114)*2 = -6* @ 0.050, or 56* advertised overlap.
Anyway Im sure half of this is too technical for most, so Ill cut it short. Stevie will have some good ideas for forced induction cams. Also you might want to ask around the sponsors and see what they think.
In fact I had one of the devices fitted by UK HSV in my GTS and it died like Steve's did. Steve resoldered his, I removed mine and just used efilive. I wrote it up here http://r8transformation.blogspot.com/ under the June 24th entry. Ive helped a couple of forum members change their tunes for SVA tests so I know it works for all models from 99 through to at least 2004.
SS HSV your idea sounds like a good plan. Im in 2 minds regarding intakes myself at present. Im off to Sema next month so thought I could get an intake at the same time. Only thing is that the FAST intake is an arse to get sealed there are loads of horror stories. Also the suggestion is to go for a Nick Williams or Holley 90mm throttle as the FAST sticks.. again horror stories.
However that all said other than the 8 tb manifolds that Harrop and some other ozzie guys make there isn't anything better that can supply more air.... except forced induction. (Im considering the 8 throttle body path mentioned as the ultimate solution).
If you are going down the cam route you are better to look at the heads first. Another potential quagmire.
There are now loads of excellent heads out there. I went with a set of Dart 205's as they were on an introductory special. The pair for $1300 US. The top of the line ones are Trickflow, ETP, and AFR, plus loads of aftermarket CNC ported 243 (LS6/LS2) heads. The ETP and TFS ones can be had with altered valve angles to increase intake. The Trickflow's flow something like 330cfm compared to stock LS1 of around 230, and stock LS2 of 270cfm.
What you want for a street NA engine is a small port with high flow. That keeps velocity up for intake enertia and helps keep the mixture turbulant. This makes for a better more consistent combustion charge less prone to detonation etc. Heads are around $2400 for a good set.
Then there is the cam.. Your nightmare has now truly begun. Terms like IVC, Overlap, LSA, Dynamic compression, quench as well as lifter and valve spring preloads etc will all be your enemy. Plus all the usual duration and lift info.
Mild cams are usually under 220 duration, with warm cams in the 220-230 range. Things get fairly heated after that. If you want max low down power stick with mid 220 and under.
Again the cam d'jour seems to be a comp cams XER lobe 224/228-112 with something like 0.590 lift. This will give excellent all round performance. Do a search on ls1tech for loads of info on it.
Ive yet to go for an mot sniff, but if emissions come into your cam choice then you will want to ensure minimal effective overlap. That means making sure you keep to 0 or less at 0.050. However that said with cats you can probably go a little lumpier. You can figure out overlap by (intake duration+exhaust duration/4)-LSA*2 In my case ((220+224/4) -114)*2 = -6* @ 0.050, or 56* advertised overlap.
Anyway Im sure half of this is too technical for most, so Ill cut it short. Stevie will have some good ideas for forced induction cams. Also you might want to ask around the sponsors and see what they think.
Edited by ringram on Sunday 24th September 22:38
I had the same problem, which was getting gradually worse. Poss. cause was the film that the converter is wrapped in shrinking & therefore tightening with age. I had it booked in to LSV to replace & re-position, but never made it.
It was getting to the stage where 100mph was reading nearer to 130! I just used my Road Angel for a speedo anyway.
I got some great tips from Paul re: new positioning etc., you could try searching back, would have been mid 2005 I'd guess.
It was getting to the stage where 100mph was reading nearer to 130! I just used my Road Angel for a speedo anyway.
I got some great tips from Paul re: new positioning etc., you could try searching back, would have been mid 2005 I'd guess.
SS HSV,
Fwiw, a FAST intake isn't appreciably better than the LS6 item and at about 900usd just not worth the money for around 8hp.
A 90mm throttle body isn't worth it either. I would stay with the 78mm for better lowdown response.
If you want to know why read here:
(In this article they tried an 84mm BBK t/body on a 454cid engine and it lost power over a stock LS6 t/body see lower graphs).
www.hotrod.com/techarticles/engine/113_0309_ls6_454ci_engine_build/rod_piston_install.html
If you need cam information, try www.compcams.com they have a cam helper here:-
www.compcams.com/Technical/CamHelp/
(You need to enter "hyd roller" and engine family)....
They also provide Dyno graphs (albeit it's of a 355cid SBC) with a load of different cams; look at the "HR" ones lower down (hydraulic roller). This will give you an idea of what gives you power where:-
www.compcams.com/Technical/DynoSheets/
There's a good cams comparison on a stock LS1 engine here:
www.samsperformance.com.au/index.php?option=com_zoom&page=view&catid=4&PageNo=1&key=3&hit=1
[Notice the smallest (212) cam makes better average power than ANY of the other bigger cams].
You'll probably find that you'll be happy enough with just a cam if it's a daily driver and you are not after high peak hp. Also if you need to pass emissions and stay with decent economy, to quote Sam himself "stay below 220 duration."
The 212/218 works very well as does the 216/220. Max lift and moderate duration with the advertised or total duration overlap below 50-55 degrees is what is reckoned to be best for a street performance car.
If you enjoy tech reading and want to understand a bit more about cams you can read one David Vizards articles here:
www.popularhotrodding.com/tech/0607phr_camshaft_basics/
Ringram either I'm a dunce or your calculation has an error.
If I put my cam specs in which are different to the example you gave, I arrive at the same figure as you.
Also how does it work when the intake and exhaust centre lines have been made with advance or retard in them?
Fwiw, a FAST intake isn't appreciably better than the LS6 item and at about 900usd just not worth the money for around 8hp.
A 90mm throttle body isn't worth it either. I would stay with the 78mm for better lowdown response.
If you want to know why read here:
(In this article they tried an 84mm BBK t/body on a 454cid engine and it lost power over a stock LS6 t/body see lower graphs).
www.hotrod.com/techarticles/engine/113_0309_ls6_454ci_engine_build/rod_piston_install.html
If you need cam information, try www.compcams.com they have a cam helper here:-
www.compcams.com/Technical/CamHelp/
(You need to enter "hyd roller" and engine family)....
They also provide Dyno graphs (albeit it's of a 355cid SBC) with a load of different cams; look at the "HR" ones lower down (hydraulic roller). This will give you an idea of what gives you power where:-
www.compcams.com/Technical/DynoSheets/
There's a good cams comparison on a stock LS1 engine here:
www.samsperformance.com.au/index.php?option=com_zoom&page=view&catid=4&PageNo=1&key=3&hit=1
[Notice the smallest (212) cam makes better average power than ANY of the other bigger cams].
You'll probably find that you'll be happy enough with just a cam if it's a daily driver and you are not after high peak hp. Also if you need to pass emissions and stay with decent economy, to quote Sam himself "stay below 220 duration."
The 212/218 works very well as does the 216/220. Max lift and moderate duration with the advertised or total duration overlap below 50-55 degrees is what is reckoned to be best for a street performance car.
If you enjoy tech reading and want to understand a bit more about cams you can read one David Vizards articles here:
www.popularhotrodding.com/tech/0607phr_camshaft_basics/
Ringram either I'm a dunce or your calculation has an error.
If I put my cam specs in which are different to the example you gave, I arrive at the same figure as you.
Also how does it work when the intake and exhaust centre lines have been made with advance or retard in them?
What spec you got Sid?
Im pretty sure its correct. Cam advance wont change overlap, that only places the overlap and valve events at a different position of stroke. (ie) overlap point advanced or retarded with respect to TDC. If you have a lower LSA you events can differ and still match mine.
Here is a link using the same forumla www.ls1tech.com/forums/showthread.php?t=561104
Or better yet (intake + exhaust)/2 - (2* LSA) which I think is the same, just rearranged. (Maths help!)
Im pretty sure its correct. Cam advance wont change overlap, that only places the overlap and valve events at a different position of stroke. (ie) overlap point advanced or retarded with respect to TDC. If you have a lower LSA you events can differ and still match mine.
Here is a link using the same forumla www.ls1tech.com/forums/showthread.php?t=561104
Or better yet (intake + exhaust)/2 - (2* LSA) which I think is the same, just rearranged. (Maths help!)
Ringram,
re. the LS1tech thread, I would hazard a semi-educated guess and say they didn't fully understand what they're talking about.
They are purporting to give 50thou duration. Overlap is calculated from total or advertised duration (usually 0.006" tappet lift for a hydraulic roller to allow for slight lifter collapse. Except for Crane, who use 0.004"
Depending on lobe design the difference between total duration and 0.050" duration could be anywhere from 50-odd degrees (Comp XER have some of the steepest ramps as you know) .....to around 70 degrees.
On the other hand I do know about David Vizard, and anyone who's worked with and read about V8's will know him as one of the finest and knowledgeable engine builders on the planet, what he doesn't know isn't worth knowing.
I'll stick with Popular Hotrodding Tech and not a bunh of keyboard "experts" ...thanks!
re. the LS1tech thread, I would hazard a semi-educated guess and say they didn't fully understand what they're talking about.
They are purporting to give 50thou duration. Overlap is calculated from total or advertised duration (usually 0.006" tappet lift for a hydraulic roller to allow for slight lifter collapse. Except for Crane, who use 0.004"
Depending on lobe design the difference between total duration and 0.050" duration could be anywhere from 50-odd degrees (Comp XER have some of the steepest ramps as you know) .....to around 70 degrees.
On the other hand I do know about David Vizard, and anyone who's worked with and read about V8's will know him as one of the finest and knowledgeable engine builders on the planet, what he doesn't know isn't worth knowing.
I'll stick with Popular Hotrodding Tech and not a bunh of keyboard "experts" ...thanks!
Edited by sid447 on Tuesday 26th September 17:12
I agree, however those calculations are exactly correct when checked against my crane cam card and some other cards. Some of the theory and comments on LS1tech may need "filtering" but formula are either right or wrong. You are right in saying overlap is best considered in total and not at 0.050, however for emissions -7* at 0.050 is said to be the max you want to go. The reason 0.050 is used more than total duration is because thats where airflow becomes significant, except for overlap where pressures are such that small openings are still important. As with anything there are loads of if's but's and and's. Only those with both knowledge and experience will know the reality. There is no such thing as too much information.
As the saying goes, every day is a learning day.
As the saying goes, every day is a learning day.
Edited by ringram on Tuesday 26th September 11:10
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