More rolling road figures to mull over
Discussion
I had an interesting car on the rollers today. Imagine someone asking for advice....." I am building a 998 Ford engine with a single 36 or 38 mm choke weber. I want 120 bhp at 9000 rpm, what do you suggest?" In your dreams I would have said....till we ran it up on the rollers.
100.3 bhp at the wheels with 16.5 losses gave 116.8 bhp at the engine at 8200 rpm.
The engine, a Cosworth 998 Formula three engine originally built in 1966 and recently engine dynoed at 120 bhp.
The car, an Alexis MK8 formula three, maybe the last one left running.
Yours for £110,000 a snip.
Peter
100.3 bhp at the wheels with 16.5 losses gave 116.8 bhp at the engine at 8200 rpm.
The engine, a Cosworth 998 Formula three engine originally built in 1966 and recently engine dynoed at 120 bhp.
The car, an Alexis MK8 formula three, maybe the last one left running.
Yours for £110,000 a snip.
Peter
Interesting point, I would note that in engineerng terms the OP has cross reference to engine dyno data, which the majority of peoples discussions do not. Hence, in my book, if there is statistical analysis, at least we have two points of reference here using divergent test techniques and gages :-) You then have to show that they are both flawed to have validity in your statement when applied to the OPs setup (- have no reference points to say what his setup is), than some generic statement of "fact"... otherwise we are back to the moon is made out of blamange arguments.. make a tasty change though :-)
Edited by MFaulks on Saturday 14th June 06:18
Absolutely no offence taken, what make of rolling road and engine dyno do you own? After 4 years ownership I am very pleased with the dynocom rollers, I get repeatable test runs so I can change small details and log the difference, even down to different oils in engines, boxes and axles. The dyno is merely a tool and a good one too. What does come across as interesting is the close correlation we seem to achieve when comparing engine dyno figures from same engine on our rollers, but hey, without knockers the world would be a less interesting place would it not? 
Maybe this rolling road is worse than a Dynocom Rolling Road? Only just mind you
https://www.youtube.com/watch?v=r5YZ9jmQKys
Peter
Maybe this rolling road is worse than a Dynocom Rolling Road? Only just mind you
https://www.youtube.com/watch?v=r5YZ9jmQKys
Peter
Again, no offence meant Peter. The problem with dynocom is that they make very well built dynos but the software is incredibly poor. Tests unrepeatable in almost all cases and countless people left with little or no comeback. Automechanika dubai last week was very interesting. I'm sure it will come out in the open very soon.
In would like to reiterate, my comment is based ONLY on the dyno and not that of theoperstor and or business whom are almost certainly of good practice.
In would like to reiterate, my comment is based ONLY on the dyno and not that of theoperstor and or business whom are almost certainly of good practice.
Hi again, still no offence taken.
I am happy to state we get repeatable results and have done for all the years we have run it. Race cars give same power curve and numbers year on year unless something has changed. Maybe I am lucky with my Dynocom but I wouldn't dream of selling it or buying anything different. We had to work hard on suppressing electrical/electronic interference right from the outset, but once mastered we have not looked back.
Peter
I am happy to state we get repeatable results and have done for all the years we have run it. Race cars give same power curve and numbers year on year unless something has changed. Maybe I am lucky with my Dynocom but I wouldn't dream of selling it or buying anything different. We had to work hard on suppressing electrical/electronic interference right from the outset, but once mastered we have not looked back.
Peter
ZeusF said:
No offence meant but I wouldn't pay any attention to figures from a DynoCom Dyno. They are almost certainly the worst dyne's in the world. Less reliable than the gold O'l Ars dyno !
Oh god. Nuh huh, no you dih'nt girlfriend. Now you're going to get the full blown passive aggressive infuriated response to anyone who even mildly criticises his rolling road which generally involves:A) So what rolling road do YOU own then? Because only people who actually own a rolling road can comment on them.
B) It's always completely repeatable - but then so is my broken watch which repeatably reports the time as 9.03.
C) It always agrees exactly with every engine dyno we've seen figures from for the same engines because of course that's the acid test of whether a rolling road is accurate regardless of how many bhp the engine lost during the process of being installed into the engine bay with the actual car's exhaust, ancilliaries and heat shrouding losses from the surrounding bodywork.
Anyway, clearly you're new in here and won't make the same mistake again
Pumaracing said:
ZeusF said:
No offence meant but I wouldn't pay any attention to figures from a DynoCom Dyno. They are almost certainly the worst dyne's in the world. Less reliable than the gold O'l Ars dyno !
Oh god. Nuh huh, no you dih'nt girlfriend. Now you're going to get the full blown passive aggressive infuriated response to anyone who even mildly criticises his rolling road which generally involves:A) So what rolling road do YOU own then? Because only people who actually own a rolling road can comment on them.
B) It's always completely repeatable - but then so is my broken watch which repeatably reports the time as 9.03.
C) It always agrees exactly with every engine dyno we've seen figures from for the same engines because of course that's the acid test of whether a rolling road is accurate regardless of how many bhp the engine lost during the process of being installed into the engine bay with the actual car's exhaust, ancilliaries and heat shrouding losses from the surrounding bodywork.
Anyway, clearly you're new in here and won't make the same mistake again
As for my dynos, I scrapped a dynocom and have 2 mustangs at the moment. 5000 and a dc150 both AWD, both linked. I'm just buying another two for my workshops.
Seriously, this was never an attack on the guys above, we have communicated very well and as mentioned, they got the dyno working themself and without the help of dynocom.
Pumaracing said:
ZeusF said:
No offence meant but I wouldn't pay any attention to figures from a DynoCom Dyno. They are almost certainly the worst dyne's in the world. Less reliable than the gold O'l Ars dyno !
Oh god. Nuh huh, no you dih'nt girlfriend. Now you're going to get the full blown passive aggressive infuriated response to anyone who even mildly criticises his rolling road which generally involves:A) So what rolling road do YOU own then? Because only people who actually own a rolling road can comment on them.
B) It's always completely repeatable - but then so is my broken watch which repeatably reports the time as 9.03.
C) It always agrees exactly with every engine dyno we've seen figures from for the same engines because of course that's the acid test of whether a rolling road is accurate regardless of how many bhp the engine lost during the process of being installed into the engine bay with the actual car's exhaust, ancilliaries and heat shrouding losses from the surrounding bodywork.
Anyway, clearly you're new in here and won't make the same mistake again
As for my dynos, I scrapped a dynocom and have 2 mustangs at the moment. 5000 and a dc150 both AWD, both linked. I'm just buying another two for my workshops.
Seriously, this was never an attack on the guys above, we have communicated very well and as mentioned, they got the dyno working themself and without the help of dynocom.
And there was I thinking I was being friendly. Seems Ok behind the scenes Dave but then again you dont know everything that happens do you? ): ):
When folk attack rollers I always ask what they run so I can get a feel for who I am chatting too, in Zeus case someone that knows his onions and isnt just a Bulls**tter armchair tuner
When you buy yourself your promised engine dyno and share stuff I will pay you more respect as you will have earned it.
All the best Dave.
If we run some engines on the MIRA engine dyno will that suffice those who cannot accept any power figures except those achieved twenty years ago when tuning ceased or will the MIRA one be faulty too?
Peter
When folk attack rollers I always ask what they run so I can get a feel for who I am chatting too, in Zeus case someone that knows his onions and isnt just a Bulls**tter armchair tuner
When you buy yourself your promised engine dyno and share stuff I will pay you more respect as you will have earned it.
All the best Dave.
If we run some engines on the MIRA engine dyno will that suffice those who cannot accept any power figures except those achieved twenty years ago when tuning ceased or will the MIRA one be faulty too?
Peter
Whats the transmission losses with those tyres Peter ?
I did a 69 Formula 5000 Lola years ago it just fitted on the rollers we couldn't do any
power runs as it would not stay in the rollers and the very wide rear tyres grew in height
went giving it some berrys ... this was running a Chevy v8 with 4 downdraft
48's a chap called Graham Hickman built it ... use to run "RATS" in Worcester
ZeusF said:
@peterburgess, Please accept my sincere apologies, I typed what I did after a lack of sleep for two weeks and in no way was this meant as a fault of you or your company. It really was just an issue personally with dynocom and shouldn't have been made on the forum.
Bad bad ZeusF. Naughty ZeusF. Get back in your basket and no walkies for you this afternoon. See what you've done now? You slag off his rollers and he has a pop at poor little me and I never even mentioned his poxy rollers! This is what happens when you poke a stick into a wasps nest. They come out and sting every bugger nearby even the ones who didn't poke the stick in.Well I hope you're happy with yourself. You've upset our contented little forum and set everyone against everyone else and it'll be chaos from now on I tell ye. Chaos and turmoil and that's a fact.
The ironic thing is this is the first time his rollers have actually arrived at, in their random "close your eyes and try and pin the tail on the donkey" sort of way they guesstimate bhp, a believable set of figures. 70 ft lbs at the wheels, say 80 at the flywheel from 1 litre and that's about on the money for a Kent engined 8 valver.
We still need to find out why they came up with 97 ft lbs per litre from another less highly developed Kent engine a while back but I suspect we shouldn't hold our respective breaths.
Anyway, yes I'm up for a bucket of popcorn and a medium cola while you're at it.
Hi Packman
The losses were 16.5 which seemed very impressive, we usually associate wide tyres and IRS with greater losses. However, the drive shafts were pretty straight compared to most IRS setups such as the TR6, bay window VWs and Renault Alpine with the PRV engine in. We were only pulling about 110 mph at 9500 rpm which also keeps losses down. The main culprit seems to be tyre losses and speed of tyres. Components vary a lot, for example; MGB four speed box in race B saps about 27 bhp, same tyres and axle with 5 speed Ford box only takes 21 bhp, 6 bhp more for accelerating with no effort!
I know Graham over the years and hope he is well and enjoying life.
Dave B
From Coltec website (was Holbay originally) X-flow race cam details
751 Race 6150/9400 rev range 7300 peak torque rpm 8470 peak bhp rpm 110 achievable bhp 68/90 90/68 timing .445 valve lift 338 degrees
The 110 bit is achievable bhp litre which would be 187bhp for a 1700, consider it may have been a 1900 with the torque readings achieved on my rollers and the bhp achievable goes to 209bhp. We have worked a lot with Holbay cams and they usually do what it says on the box. The 209-187 spread is in the region of what we measured.
http://www.coltecracing.com/camshafts.html
Peter
The losses were 16.5 which seemed very impressive, we usually associate wide tyres and IRS with greater losses. However, the drive shafts were pretty straight compared to most IRS setups such as the TR6, bay window VWs and Renault Alpine with the PRV engine in. We were only pulling about 110 mph at 9500 rpm which also keeps losses down. The main culprit seems to be tyre losses and speed of tyres. Components vary a lot, for example; MGB four speed box in race B saps about 27 bhp, same tyres and axle with 5 speed Ford box only takes 21 bhp, 6 bhp more for accelerating with no effort!
I know Graham over the years and hope he is well and enjoying life.
Dave B
From Coltec website (was Holbay originally) X-flow race cam details
751 Race 6150/9400 rev range 7300 peak torque rpm 8470 peak bhp rpm 110 achievable bhp 68/90 90/68 timing .445 valve lift 338 degrees
The 110 bit is achievable bhp litre which would be 187bhp for a 1700, consider it may have been a 1900 with the torque readings achieved on my rollers and the bhp achievable goes to 209bhp. We have worked a lot with Holbay cams and they usually do what it says on the box. The 209-187 spread is in the region of what we measured.
http://www.coltecracing.com/camshafts.html
Peter
Pumaracing said:
ZeusF said:
@peterburgess, Please accept my sincere apologies, I typed what I did after a lack of sleep for two weeks and in no way was this meant as a fault of you or your company. It really was just an issue personally with dynocom and shouldn't have been made on the forum.
Bad bad ZeusF. Naughty ZeusF. Get back in your basket and no walkies for you this afternoon. See what you've done now? You slag off his rollers and he has a pop at poor little me and I never even mentioned his poxy rollers! This is what happens when you poke a stick into a wasps nest. They come out and sting every bugger nearby even the ones who didn't poke the stick in.Well I hope you're happy with yourself. You've upset our contented little forum and set everyone against everyone else and it'll be chaos from now on I tell ye. Chaos and turmoil and that's a fact.
The ironic thing is this is the first time his rollers have actually arrived at, in their random "close your eyes and try and pin the tail on the donkey" sort of way they guesstimate bhp, a believable set of figures. 70 ft lbs at the wheels, say 80 at the flywheel from 1 litre and that's about on the money for a Kent engined 8 valver.
We still need to find out why they came up with 97 ft lbs per litre from another less highly developed Kent engine a while back but I suspect we shouldn't hold our respective breaths.
Anyway, yes I'm up for a bucket of popcorn and a medium cola while you're at it.
you can't blame me for this. Likewise I can understand why Peter would be upset but credit given where it is due, they have almost completely rebuilt this rig to make it reliable so although in general my comment was accurate, in this case it wasn't. Ill take it on the chin for my mistake.The odd thing really in all of this is how well built the dyne is, 1/4" steel, 1/3" steel and ability to test speed at well over 300kph but the letdown is the software. if they could master that and sort out the niggles before shipment they would have a sweet setup.
Anyway, it is all relevant these days as the new generations of cars won't allow 2wd or 4wd dynes to measure them unless mechanically linked so most people will have to change regardless.
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