BHP of Full race 1700 X-flow
Discussion
Seconded..
Torque is a measure of how well the engine is working, effectively VE, power is how many times it's doing it, out and out race engines often trade a little torque for work done, I have a bulls
t busting spreadsheet that will calculate max BHP figures for a given capacity at various ROM and predict the RPM required to make a particular output. The torque values for a 2 valve engine range from 60 per litre to 80 per litre, with 4 valve engines around 70 to 90.
Dave
Torque is a measure of how well the engine is working, effectively VE, power is how many times it's doing it, out and out race engines often trade a little torque for work done, I have a bulls
t busting spreadsheet that will calculate max BHP figures for a given capacity at various ROM and predict the RPM required to make a particular output. The torque values for a 2 valve engine range from 60 per litre to 80 per litre, with 4 valve engines around 70 to 90.Dave
So are you saying the Americans are lying for 2 valve engines? The numbers you quote for lbsft per litre are as if they are constants and they are not.
NHRA Pro stock is 500 cu in or 8.195 litres. 1400 + horsepower and over 800 lbft torque, so 170 hp and 97 lbft per litre.
Nascar 5868 cc and 835 hp, 540+ torque. So 142 hp and 92 lbft per litre.
Peter
NHRA Pro stock is 500 cu in or 8.195 litres. 1400 + horsepower and over 800 lbft torque, so 170 hp and 97 lbft per litre.
Nascar 5868 cc and 835 hp, 540+ torque. So 142 hp and 92 lbft per litre.
Peter
The values I use are from experience of a wide range of engines, i am sure that they could be bettered, but not by a lot, there is only so much air you can get into a cylinder when you have a maximum operating pressure differential of 1 bar. Ultimately if the cylinder is 100% full the torque can be calculated , there is no magic, just a certain amount of fuel with known calorific value being burned.
Dave
Dave
Peter I'm not interested in discussing V8 engines in a thread about a Crossflow and the specific question of why crossplane crank V8s seem to show somewhat higher torque outputs than inline 4 pots was raised in here a few years ago but no one including DV could throw much light on it. I think there may well be lessons from the firing order combined with the tunnel ram inlet manifolds those engines use but that's for another time.
You've been given my numbers for 2v 4 pot torque per litre, the same ones now from Dave Andrews and confirmation in an actual Crossflow dyno shootout.
The only final thing I'll add is that if the Anderson you mention is Frank Anderson from down Bristol way then I'm already familiar with, how shall I put it tactfully, the "exuberance" of his power claims compared to independent tests, at least in the Brisca Pinto engines of his I got to rebuild and improve. Claiming big numbers doesn't make someone a state of the art engine builder. It just makes them someone who claims big numbers.
If you still really think you have a 96 ft lb per litre engine there then we will have to leave you to it as I fear any further debate will be as pointless as trying to convince a born again Christian fundamentalist that the earth is not really 6000 years old. Mildly diverting for a while the first time you meet one of those people but ultimately enough to make you want to stab your own eyes out with rusty nails.
You've been given my numbers for 2v 4 pot torque per litre, the same ones now from Dave Andrews and confirmation in an actual Crossflow dyno shootout.
The only final thing I'll add is that if the Anderson you mention is Frank Anderson from down Bristol way then I'm already familiar with, how shall I put it tactfully, the "exuberance" of his power claims compared to independent tests, at least in the Brisca Pinto engines of his I got to rebuild and improve. Claiming big numbers doesn't make someone a state of the art engine builder. It just makes them someone who claims big numbers.
If you still really think you have a 96 ft lb per litre engine there then we will have to leave you to it as I fear any further debate will be as pointless as trying to convince a born again Christian fundamentalist that the earth is not really 6000 years old. Mildly diverting for a while the first time you meet one of those people but ultimately enough to make you want to stab your own eyes out with rusty nails.
Gentlemen, thank you for explaining the figures are what you both feel may be maxima not hard and fast rules.
Perhaps of interest re F1 engines, I understand the single ring pack leads to horrendous blow by so the Holy Grail is high rpm bhp not good cylinder filling as the blow by would be even worse, what say you gentlemen?
Dave the rolling road calibration was done in Texas when it was built for us. The mainstay is inertia testing so unless the rollers gain or lose a lot of weight the calibration will not change. The bearings are molly coddled and we would hopefully see on coastdown tests if frictional losses all seemed higher than usual implying dying bearings (mind you one usually hears and feels poorly bearings) The pau is calibrated against the inertia rollers. The figures may or not be correct but three dynocom dynos all give the same curves for same cars when run on them all. Doesnt mean the figures are correct but does imply consistency of manufacture and calibrating does it not?
I have a few folk digging out some power and torque figures for some special engines, if I ever get them I will post them for folk to peruse.
I am not trying to be aggressive but an answer or explanation re the Nascar and NHRA figures would be nice.
Peter
Perhaps of interest re F1 engines, I understand the single ring pack leads to horrendous blow by so the Holy Grail is high rpm bhp not good cylinder filling as the blow by would be even worse, what say you gentlemen?
Dave the rolling road calibration was done in Texas when it was built for us. The mainstay is inertia testing so unless the rollers gain or lose a lot of weight the calibration will not change. The bearings are molly coddled and we would hopefully see on coastdown tests if frictional losses all seemed higher than usual implying dying bearings (mind you one usually hears and feels poorly bearings) The pau is calibrated against the inertia rollers. The figures may or not be correct but three dynocom dynos all give the same curves for same cars when run on them all. Doesnt mean the figures are correct but does imply consistency of manufacture and calibrating does it not?
I have a few folk digging out some power and torque figures for some special engines, if I ever get them I will post them for folk to peruse.
I am not trying to be aggressive but an answer or explanation re the Nascar and NHRA figures would be nice.
Peter
peter, prostock 100lb-ft/L+ and other 2V V8 that are pushing ~95lb-ft/L e.g. nascar, v8 supercars etc) use dedicated developed cylinder heads for racing. these are highly developed for highly competitive forms of racing with large amounts of R&D.
i recall vizard saying something about TQ/L about one of his old school 2V engines (non V8) being better than F1 4V engines at the time. i will have to dig it out to see if there more specifics noted and the engine he refereed.
i recall vizard saying something about TQ/L about one of his old school 2V engines (non V8) being better than F1 4V engines at the time. i will have to dig it out to see if there more specifics noted and the engine he refereed.
I love you engine builder guys having a go at each other. I'm old enough to remember pushrod engined Mallocks showing twin cams the fastest way to the line. Based on 701m short stroke blocks they would rev to 8k and last a season.
I raced against Dan Cox's Anderson engined Lotus Cortina with my 206 bhp Pinto and it was even stevens all the way to the line. The cortina was put away after 2 races and the old Pinto completed another 70 races with minimum fuss.
Engine power is fine talk amongst the punters but reliable consistent lap times and longevity is where it's at.
I raced against Dan Cox's Anderson engined Lotus Cortina with my 206 bhp Pinto and it was even stevens all the way to the line. The cortina was put away after 2 races and the old Pinto completed another 70 races with minimum fuss.
Engine power is fine talk amongst the punters but reliable consistent lap times and longevity is where it's at.
Interesting that more recent V8 USA stuff is 100+lbsft/litre.
This seems to make a mockery of, and blow into the weeds, the 80lbsft/litre max torque/litre rule imposed by DA DB and MaxToruqe does it not? You cant have an 80 limit except for Nascar/NHRA engines as they are different from the rules governing all other 2 valve engines can you?
It doesnt matter if it is by virtue of special cylinder heads, after all, is that not what we try and do when we modify heads? Paul Ivey has told me a lot about the CNC machines producing the Nascar heads.
Moss remanufacture the TR4 Cast Iron head, it has been improved as there has been input from a few head modifiers and is a better base casting than the original. I started work on TR4 engines in 1986, first championship 1987,88,89 etc etc We pushed the engine bhp up by 35 to 162 at the wheels over those three years. It helped development as folk beat a path to use our rolling road and head modding abilities. We continue to improve the TR4 engine, with some £100000 invested by a TR4 race driver (not that we have seen anything like...just lots of dyno time and about 10 heads developed. With independant engine dyno work and rolling road work we are all agreeing on 177 at the wheels and just over 200 at the engine. Engine dyno suggests lbsft/litre is 87 on the best we have all done together ( five businesses working on this as a project...engine dyno not Agra or Anderson). What I am trying to say is the power creeps forwards under development. We have pushed, with limited monetary input, the TR4 Race Engine from 162 in 1989 to 177 at the wheels in 2014, not lots but steady progress. Imagine what the TR4 engine would produce if it was the Nascar engine of choice, I am willing to bet it would make our efforts look crap
DB says maybe USA V8 is special case re firing order or some such magic stuff. Maybe it is because the 2v American V8 just happens to be the most developed engine in the World? Extending this thought, if the Nascar/NHRA engine of choice was the Pinto, Essex, Kent, A series, B series etc etc would that not be doing 100+lbsft/litre instead of the clunky old USA V8?
Peter
This seems to make a mockery of, and blow into the weeds, the 80lbsft/litre max torque/litre rule imposed by DA DB and MaxToruqe does it not? You cant have an 80 limit except for Nascar/NHRA engines as they are different from the rules governing all other 2 valve engines can you?
It doesnt matter if it is by virtue of special cylinder heads, after all, is that not what we try and do when we modify heads? Paul Ivey has told me a lot about the CNC machines producing the Nascar heads.
Moss remanufacture the TR4 Cast Iron head, it has been improved as there has been input from a few head modifiers and is a better base casting than the original. I started work on TR4 engines in 1986, first championship 1987,88,89 etc etc We pushed the engine bhp up by 35 to 162 at the wheels over those three years. It helped development as folk beat a path to use our rolling road and head modding abilities. We continue to improve the TR4 engine, with some £100000 invested by a TR4 race driver (not that we have seen anything like...just lots of dyno time and about 10 heads developed. With independant engine dyno work and rolling road work we are all agreeing on 177 at the wheels and just over 200 at the engine. Engine dyno suggests lbsft/litre is 87 on the best we have all done together ( five businesses working on this as a project...engine dyno not Agra or Anderson). What I am trying to say is the power creeps forwards under development. We have pushed, with limited monetary input, the TR4 Race Engine from 162 in 1989 to 177 at the wheels in 2014, not lots but steady progress. Imagine what the TR4 engine would produce if it was the Nascar engine of choice, I am willing to bet it would make our efforts look crap
DB says maybe USA V8 is special case re firing order or some such magic stuff. Maybe it is because the 2v American V8 just happens to be the most developed engine in the World? Extending this thought, if the Nascar/NHRA engine of choice was the Pinto, Essex, Kent, A series, B series etc etc would that not be doing 100+lbsft/litre instead of the clunky old USA V8?
Peter
Edited by PeterBurgess on Friday 4th April 06:36
Maybe I'm being obtuse, but why the heck are you attempting to compare an inline 4 pot with a V8 in terms of output, they're completely different engine designs.
Why not compare to a V4, or a boxer? At least then you've the same number of cylinders as a basis of similarity.
Also I've noticed that US dyno's seem to read significantly higher than UK dynos, maybe that's where it's all going wrong. (In MX5 circles, it's generally accepted that what a US car gets at the wheels is what we see at the flywheel).
As an aside, my MX5 engine makes more power than a 2013 F1 engine - at 6500rpm, WOOT!
Why not compare to a V4, or a boxer? At least then you've the same number of cylinders as a basis of similarity.
Also I've noticed that US dyno's seem to read significantly higher than UK dynos, maybe that's where it's all going wrong. (In MX5 circles, it's generally accepted that what a US car gets at the wheels is what we see at the flywheel).
As an aside, my MX5 engine makes more power than a 2013 F1 engine - at 6500rpm, WOOT!
Edited by Richyvrlimited on Friday 4th April 11:51
What is being compared and questioned is the torque per litre of a number of different engines, not the absolute output, the maximum for this value should be broadly similar between engines with the same number of valves per cylinder irrespective of the actual engine configuration and engine size.
Just to add that the assumptions about torque made in my spreadsheet are for production based engines, not purpose made racing engines with specifically designed and developed cylinder head etc. there are limits on how much torque you can get from a litre of fuel/air mixture given pump fuels. I haven't done the maths but I think that to achieve 100lb/ft per litre would require volumetric efficiency in excess of 100%.
Dave
Just to add that the assumptions about torque made in my spreadsheet are for production based engines, not purpose made racing engines with specifically designed and developed cylinder head etc. there are limits on how much torque you can get from a litre of fuel/air mixture given pump fuels. I haven't done the maths but I think that to achieve 100lb/ft per litre would require volumetric efficiency in excess of 100%.
Dave
DVandrews said:
I haven't done the maths but I think that to achieve 100lb/ft per litre would require volumetric efficiency in excess of 100%.
Dave
Even standard road engines achieve 100% VE. Full race ones achieve 130% or more. This is discussed here.Dave
https://web.archive.org/web/20110918114921/http://...
This gives a rough and ready guide for engines on pump fuel and normal CRs that VE percentage is approximately 1.4 times peak torque per litre in ft lbs hence a stock 4v road engine producing 72 ft lbs per litre just about achieves 100% VE.
Obviously engines running higher octane fuel and higher CR achieve more torque for a given airflow and the multiplier of 1.4 changes.
I'll leave you to set up your own spreadsheet but another way of working back to VE is by consideration of BSFC for which data is more readily available, air/fuel ratio by mass and hence engine airflow vs nominal piston displacement.
Take a stock 2 litre 4v road engine producing 72 ft lbs per litre at 4000 rpm (109.7 bhp) at a BSFC of 0.47 lbs/hp/hr (286 grams/kWhr), an A/F ratio of 12.6, fuel density of 0.75 kg/lt and air density of 1.225 kg/cubic metre.
If you work the calculations correctly you should find that inducted airflow is approx 82 grams/sec (141 CFM), VE is 100% and the torque multiplier is 1.39.
Perhaps before I bust Dave Vizard's balls too much on this topic Peter Burgess can clarify what fuel octane and CR this Crossflow he thinks has 96 ft lbs per litre is running on. He might also post the 201 bhp SAE flywheel power curve he believes it generates so we don't have to guess the torque numbers from the wheel figures.
198bhp from a 1.7 xflow pushrod @ 6950rpm and 162lb/ft @6100rpm with 45's and 36mm chokes!
Never heard such BS
First of all rolling road figures are notoriously st for accuracy, only a calibrated DYNO can give accurate results that is when the BS stops
Second, to get that power from a 1.7 pushrod at only 6950rpm the head would have to flow Huge amounts of air
The only possible way to get that power at low revs would be to have a custom head cast with fully downdraft inlet ports and huge valve sizes along with an OHC conversion or at least a billet custom cam and much larger followers
As for comparing power figures from current V8 race engines, get real! they have needle roller cam bearings, roller lifters, completely custom cast heads, searching for every last bhp and lb/ft
If given a high enough budget it would be just possible to get those power figures but for sure the head and valvetrain would have to be MAXED OUT
Anyone else notice how this was posted on the 1st of April! LOL
Never heard such BS
First of all rolling road figures are notoriously s
t for accuracy, only a calibrated DYNO can give accurate results that is when the BS stopsSecond, to get that power from a 1.7 pushrod at only 6950rpm the head would have to flow Huge amounts of air
The only possible way to get that power at low revs would be to have a custom head cast with fully downdraft inlet ports and huge valve sizes along with an OHC conversion or at least a billet custom cam and much larger followers
As for comparing power figures from current V8 race engines, get real! they have needle roller cam bearings, roller lifters, completely custom cast heads, searching for every last bhp and lb/ft
If given a high enough budget it would be just possible to get those power figures but for sure the head and valvetrain would have to be MAXED OUT
Anyone else notice how this was posted on the 1st of April! LOL
I've had some interesting feedback from DV. In the nearly 40 years since he wrote his Pinto book he's up from the 82 ft lbs per litre he maxed out at back then to about 85 now. Very good for a 2v 4 pot IMO but obviously a mile away from what any of us can achieve from almost any 4v 4 pot just by doing a decently ported head, buying off the shelf cams and slapping it all together. Quite where the 4v advantage specifically resides is another matter which we need to discuss further but it can only really be in the head and valvetrain as everything else can be made very similar.
American V8s are totally non comparable. Every original part of the Chevy or Ford engines from the 50s has been redesigned to remove every stock restriction. Custom cast heads, CNC machined, with ports big enough to supply any valve size. Discharge coefficients on the inlet side 15% to 20% higher than anything we could achieve from an average stock 2v 4 pot head before hitting a waterway. Millions of man hours spent on flowbenches and dynos optimising port and chamber shapes, valve trains, exhaust and inlet manifolds.
The only way to get a Crossflow even close to what he's achieved on the Pinto would mean changing so much it wouldn't be a Crossflow any more. Redesign the head and pistons from scratch for starters to make the ports more downdraft and much bigger, put a proper combustion chamber in there and use normal pistons to get a decent burn. Eliminate all the flex in the valve train with bigger cam bearings and lobes, move it higher in the block to shorten the pushrods, redesign the rockers and increase their ratio. A few million quid should cover it though.
Anyway, I think this particular horse has been flogged enough.
American V8s are totally non comparable. Every original part of the Chevy or Ford engines from the 50s has been redesigned to remove every stock restriction. Custom cast heads, CNC machined, with ports big enough to supply any valve size. Discharge coefficients on the inlet side 15% to 20% higher than anything we could achieve from an average stock 2v 4 pot head before hitting a waterway. Millions of man hours spent on flowbenches and dynos optimising port and chamber shapes, valve trains, exhaust and inlet manifolds.
The only way to get a Crossflow even close to what he's achieved on the Pinto would mean changing so much it wouldn't be a Crossflow any more. Redesign the head and pistons from scratch for starters to make the ports more downdraft and much bigger, put a proper combustion chamber in there and use normal pistons to get a decent burn. Eliminate all the flex in the valve train with bigger cam bearings and lobes, move it higher in the block to shorten the pushrods, redesign the rockers and increase their ratio. A few million quid should cover it though.
Anyway, I think this particular horse has been flogged enough.
PeterBurgess said:
Perhaps of interest re F1 engines, I understand the single ring pack leads to horrendous blow by so the Holy Grail is high rpm bhp not good cylinder filling as the blow by would be even worse, what say you gentlemen?
I say false. The scavenge pump assemblies on our engines are a work of art in themselves and at 17,000RPM we see around 500mbar depression in the crank case. The single compression ring actually seals extremely well in these conditions and we lose very little to blow by. It's worth noting the rings aren't like a conventional road car ring and are essentially gapless. We also do not have to deal with cold starts and run pistons which as a combination of the material they are produced from and the design of the piston/bore/block do not expand in the same way a road car piston does which means we can run much tighter tolerances than a road car based engine can.Our most advanced engines calibrated for 102 octane fuel are producing over 700bhp @ 17,000RPM but produce over 300NM of torque from 12,000 RPM to the limiter. Peak torque BMEP is approaching 14 bar which whilst not extreme on it's own is quite good when you consider that's at 14K RPM on an engine with 115mm long con rods and you don't achieve that BMEP at those speeds or VEs in the 115% region without good cylinder filling. In qualifying spec on big fuels these engines were achieving nearly 118% VE and North of 14bar BMEP. Maybe more impressive is that these days we run to 1000KM between rebuilds with a single basic inspection at 700KM. Not a lot can manage over 235bhp/litre NA and last that long.
More impressive maybe is that 5 years later on the V8s they were up to 20K RPM, 125% VE and well over 300bhp/litre.
Edited by poppopbangbang on Tuesday 8th April 01:21
Poppop......Thanks for the first hand knowledge input re the F1 engines. Have the new fuel efficiency rules had much imapact on bhp/litre lbsft/litre? Too much info on PH is second and even third hand. I am happy to post power graphs for folk to see. Gives something to get teeth into
Dave B, I remember DV stating he had achieved 86 lbsft litre ( not sure which year) with a low 10.9:1 CR pinto (seemingly mild cammed), would this not have been better with higher CR and better fuel? It didnt say what year this was tested. See Stan Weiss interview Piston Heads.
What is interesting is DV saying about packages working. We have found massive differences in lbs/ft litre in fast road MGB engines with experimenting with off the shelf ex systems , 69 lbsft/litre with ubiquitous LCB to 75 lbs ft litre with 3 into 1 narrower primary manifold! Lost top end above 5000 rpm though! Lots and lots of hands on testing eventually evolves a package/combo that works well.
So it looks as if, if we accept DV is not being economical with the truth, we have moved on from a max achievable lbs/ft per litre at the onset of this thread to 85/86 rather than an inflexible 70/80 ? And we ignore the 2v 100+ from V8 engines as they have been developed so much? Which means the 87lbsft litre we reckon for the extra £100,000 spent developing the TR4 engine does not look pie in the sky?
Now those involved in racing whether humble track, sprint/hillclimb I work on to F1/nhra/nascar are all trying to find the edge for their engines and drivers and I still put it to all the poohpoohers, lbs/ft litre moves upwards with year on year development of that engine under race use.
Peter
Dave B, I remember DV stating he had achieved 86 lbsft litre ( not sure which year) with a low 10.9:1 CR pinto (seemingly mild cammed), would this not have been better with higher CR and better fuel? It didnt say what year this was tested. See Stan Weiss interview Piston Heads.
What is interesting is DV saying about packages working. We have found massive differences in lbs/ft litre in fast road MGB engines with experimenting with off the shelf ex systems , 69 lbsft/litre with ubiquitous LCB to 75 lbs ft litre with 3 into 1 narrower primary manifold! Lost top end above 5000 rpm though! Lots and lots of hands on testing eventually evolves a package/combo that works well.
So it looks as if, if we accept DV is not being economical with the truth, we have moved on from a max achievable lbs/ft per litre at the onset of this thread to 85/86 rather than an inflexible 70/80 ? And we ignore the 2v 100+ from V8 engines as they have been developed so much? Which means the 87lbsft litre we reckon for the extra £100,000 spent developing the TR4 engine does not look pie in the sky?
Now those involved in racing whether humble track, sprint/hillclimb I work on to F1/nhra/nascar are all trying to find the edge for their engines and drivers and I still put it to all the poohpoohers, lbs/ft litre moves upwards with year on year development of that engine under race use.
Peter
Edited by PeterBurgess on Tuesday 8th April 07:17
Edited by PeterBurgess on Tuesday 8th April 07:27
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