If the dyno is only measuring roller speed (kph) then it will only know the wheel HP, and wheel torque (or more accurately force).
If the dyno is attached to the tacho of the engine, then it can calculate the engine torque, but measured at the wheels so less the efficiency.
Does the dyno graph plot HP vs road speed? If so you will have to calculate the torque. You will need to know what gear the dyno pull was done in, and what ratio that gear and the diff ratio was, along with the tyre diameter. If the torque quoted was roller torque then you need to know the roller diameter too.
If the dyno is only measuring roller speed (kph) then it will only know the wheel HP, and wheel torque (or more accurately force).
If the dyno is attached to the tacho of the engine, then it can calculate the engine torque, but measured at the wheels so less the efficiency.
Does the dyno graph plot HP vs road speed? If so you will have to calculate the torque. You will need to know what gear the dyno pull was done in, and what ratio that gear and the diff ratio was, along with the tyre diameter. If the torque quoted was roller torque then you need to know the roller diameter too.
The dyno can be either directly connected to the coil for the tacho or by inputting a ratio on the tacho to the rollers.
It can graph to road speed or engine rmp.
The gearing etc can be input for it to work out engine HP and torque as well as at the wheels.
HotRodMatt wrote:The dyno can be either directly connected to the coil for the tacho
That's what I said, so yes.
or by inputting a ratio on the tacho to the rollers.
That's not normally done. If they don't connect the tacho then they simply plot HP vs road speed.
The gearing etc can be input for it to work out engine HP and torque as well as at the wheels.
Actually the dyno doesn't need to know the gearing or engine speed to calculate the wheel HP.
And a chassis dyno will never calculate engine HP. The operator may use a rule of thumb gearbox efficiency to give an indication of flywheel HP, but again doesn't need to know anything about the ratios.
The dyno will measure wheel force, the force acting tangential to the wheel. If the dyno knows the engine rpm it can calulate the torque from the HP readings, but again it will be out by the gearbox efficiency.
If you don't know the rpm readings, you can convert the wheel force or roller torque to an equivalent engine torque using the gear ratios and tyre diameter, but again it will be out by the gearbox efficiency.
I have converted a HP vs road speed graph to HP vs rpm and then torque vs rpm for Craig in the past. It is in one of the old threads.
Rear wheels =121.5hp at 6000rpm
At the Flywheel= 147.8hp at 6000rpm
Torque = 700 ft lb at 4500rpm
This is impressive HP for these revs keeping in mind this is a stock stroke motor. Very nice combo.
By the way in my other post regarding tuning I wasn't sugesting that Stan doesn't tune motors for customers but rather that a lot of his engines are sent as long engines without accessories such as carbs etc. Therefore it would be very hard for him to control what the customer does.
Andrew Grace
BizarreModeratorThe artist formerly known as blue74l
Gracey wrote:Rear wheels =121.5hp at 6000rpm
At the Flywheel= 147.8hp at 6000rpm
Torque = 700 ft lb at 4500rpm
stop quoting the 700ft.lbs, it's got nothing to do with the engine.
121.5HP @ 6000rpm equates to 106 ft.lbs of torque.
The peak torque is usually produced lower in the rev range than the peak power so peak torque will be more than 106ft.lbs, my guess is prob close to 120ft.lbs.
And that engine HP is an estimate, by using the wheel HP and dividing by an estimated gearbox efficiency. So it should say estimated engine HP ~ 148HP.
An 8 liter V10 Dodge Viper motor has a little under 500ft.lbs of torque. So that gives you an idea how out of whack quoting the 700ft.lbs figure looks.
Wes is there any difference in using either 3rd or 4th gear, all of my dyno tests have been done in third but I think I read somewhere that the 120 from the 1916 was done in 4th.
The reason I ask is that in one of the American mags, they were commenting on a particular cars output & they also said that they 'only' used 3rd gear whereas all the other cars used 4th gear. Does it make a lick of difference??
regards
Jak
Congratulations to Ben Durie for breaking the hillclimb record at Ringwood in his stroker beetle!
yes, surely there's some reason it could be wrong 😉
did the american mag say what the ratios were? or the wheel diameters? does it matter at ALL? maybe their 4th was the other guys third anyway...
while we're at it, what speeds at what revs determine whether you have an L-bug gearbox or a superbug gearbox?
I'm doing 270 Kph in third at 1200 rpm 😉
is that tall? hehehe
let sleeping dubs lie
Craig Torrens6 times Australian, 7 times State Hillclimb Class Champion
Baja Wes wrote:The torque quoted is torque at the wheel or rollers. It is completely different to the torque at the engine, as torque is multiplied up by the gear and diff ratios, and reduced by the gearbox efficiency.
HP is not effected by the gear ratios, only the gearbox efficiency.
Basically those torque figures mean nothing and are only comparitive to each other, as long as they were both achieved in the same gear.
Jak, here is your answer re HP. Basically Horsepower is the same in every gear because you are not changing the horsepower of the motor. The motor is still producing the same Horsepower regardless of gearing, what changes is the torque. A gearbox is a torque multipler. So if you did a dyno run in first gear the HP will be the same but the torque will be massive compared to say 4th gear.
I have since found out that Troy's Dyno run was done in third gear, the same gear as his dyno day run .:thumb
There are two basic types of dyno's, inertial and load types. Inertial are usually the cheapest and are more prone to the effects of gear selection, because each gear multiplies the drivetrain inertia differently (a square of the ratio).
A dyno dynamics dyno is a load type dyno and is more accurate. The company has also made what they call "shoot-out" mode. They have made it as an industry standard method of testing HP, so no matter which dyno you test the car on you get the same results.
The load type dyno is still effected by drivetrain inertia but not as badly. The operator will enter the vehicles drivetrain inertia from a standard list of vehicles, however if the drivetrain or engine is modified the figure will be slightly out. This can lead to a small difference in HP figures between gears. Some gears are also slightly different in efficiency than others.
So dyno guys will dyno the car in the highest gear possible, without exceeding the max roller speed. The max roller speed on most dynos is between 200-250kph, so third gear on a VW is normally used.
Gracey wrote:Therefore it would be very hard for him to control what the customer does.
Andrew Grace
Does he still offer warranty on long blocks??
Stuffed if i would!
Well I brought my steriods years ago as a long block and it came with a warranty. So I guess so but you would have to check with Stan. What I do know is that Stan invests a lot of time helping and advising his customers so as to get the best setup. What they do with that advice is up to them.
Gracey wrote:Rear wheels =121.5hp at 6000rpm
At the Flywheel= 147.8hp at 6000rpm
Torque = 700 ft lb at 4500rpm
stop quoting the 700ft.lbs, it's got nothing to do with the engine.
121.5HP @ 6000rpm equates to 106 ft.lbs of torque.
The peak torque is usually produced lower in the rev range than the peak power so peak torque will be more than 106ft.lbs, my guess is prob close to 120ft.lbs.
And that engine HP is an estimate, by using the wheel HP and dividing by an estimated gearbox efficiency. So it should say estimated engine HP ~ 148HP.
An 8 liter V10 Dodge Viper motor has a little under 500ft.lbs of torque. So that gives you an idea how out of whack quoting the 700ft.lbs figure looks.
I'll take your word for it regarding torque but my post was referring to the HP made at a given rpm for a stock stroke motor ie. a lot at relatively low rpm.
Thats nice power, and makes me very happy as my pobjoy 1916 base with ally case and 40 dells is ready and waiting for the rest of my car to catch up. Mine however is not the steroids version i wonder if ill get 100 + hp ? On the cost side of things i recently got three quotes from three diff builders A Pobjoy and a pro built stroker and a pro built type 4 i dont mind telling that i went with the pobjoy, the prices were roughly as follows
Pobjoy 1916 base with ally case complete no carbies $6700.
Stroker 75.5 * 90.5 no clutch, carbies ,exhaust , tin ware $ 8800
Type 4 conversion total rebuild complete with porche fan and alternator ,no carbies $9700.
For comparison i also just bought a total new head to head stock 1600 fitted for my girlfriends car and it was $2150.
I am not sure what people are going to think about the etiquette of me putting these figures on here but in my view this is relevant information ( prices obtained 4 weeks ago, and rounded to nearest $100) that any body can obtain with the willingness to make 3 phonecalls. The steroids version (u can get price of the pobjoys) is more again I hope this doesn,t upset to many people.:kiss
oops i forgot something, Once i get motor in my car i will need somebody in the melb area to dyno tune and jet my car for me it will be running 40 drlas that were previously on a 1835. Can anybody recommend somebody with relevant know how that will be willing to tune a new motor built by some one else, i dont wanna get caught up in the whole whos best builder bull i just would like to know who i can go to help get the most out of my new baby? A friend mentioned that a porche race shop might be the go?
:thumb :thumb congrats bigbruvabob. you're gonna love it 😀:thumb :thumb
someone once said there are three things you choose a motor based on (cost, reliability, and power) but you can only have two. looks like you managed to get all three 😀😀😀😀
let us know how it goes, I beat the crap outta my base 1916, and sold it to Craig after that in kit form (pulling it down showed that it was in obscenely good nick) except for the 94's which I kept for the steroids motor.
have fun, but don't lose your license 😀
let sleeping dubs lie
Craig Torrens6 times Australian, 7 times State Hillclimb Class Champion
bigbruvabob wrote:Pobjoy 1916 base with ally case complete no carbies $6700.
Stroker 75.5 * 90.5 no clutch, carbies ,exhaust , tin ware $ 8800
Thanks for the prices :thumb
WOW $8800 for the stroker long block :jesus Then add another $1500 for new Carbies, $300-$500 for a clutch, $400 for exhaust, tinware etc etc that's well over $11000 !
I think some people are getting confused between engine torque, and tractive effort which is a measure at the rollers, and is not a direct link to engine power.
Tractive effort is essentially torque at the wheels. A gearbox is a torque converter. I think most people are more interested in what is happeneing at the wheels than at the flywheel.
For those who want flywheel readings the machine can be given the info and it can calculate back. Some dynos even have hundreds of factory combinations to choose from to give this information.
ok here we go, new alluminium case, crank ground and lynished, all new bearings and seals,37/68 cam,hd 30mmoil pump,new pushrod tubes, new 94 p and c, anti surge deep sump,crom stud kit,trw 040 comp heads ported and matched to new manifolds,soft bonded clutch and pressure plate,009 dizzy and squizot coil,thunderbird extractors and clamp kit, spakplugs and ignition cables,new oil cooler,decked lightened and dowelled flywheel,dynamic balancing, other bits and pieces and stans magic, i supplied generator,some tin and a pair of 40 dells which i am hoping will give me a bit more hp over the standard base kadrons.am also going to fit a porche fan alt and shroud as soon as i russle up another grand.😎
its standard i was going to get the c/w crank it costs about $600 more but stan said that it really wouldn't make much diff without the more serious heads and carbs that he uses on the steroids motor and that if i wanted to upgrade to the roids motor at a later date he would still have to tear it all down to do anyway.😎
Craig Torrens6 times Australian, 7 times State Hillclimb Class Champion
That's pretty impressive; peak stock horsepower from about 3050 rpm, and generally uphill all the way from there... Peak power at 5800-ish... That seems to be a very useable power curve! Hell, I'd be happy if my kombi made that kind of power!! :o
I'd love to see a torque curve - was it graphed at all?
Kruizin Kol
Craig Torrens6 times Australian, 7 times State Hillclimb Class Champion
