Let Your Car Idle For 30 Minutes When Cold.....
Discussion
Avocet said:
Trooper2 said:
Americans know plenty about conserving fuel. Europe isn't building engines as large as the US that can match US performance and fuel economy.
Best laugh I've had all day!
The statement is pretty much on the money.
Real world fuel economy figures from a Mustang V8 and Corvette are in excess of 30 UK MPG. Hardly bad. Especially when you consider the performance available.
Avocet said:
Trooper2 said:
Americans know plenty about conserving fuel. Europe isn't building engines as large as the US that can match US performance and fuel economy.
Best laugh I've had all day!
Well here are some comparisons for you, I'll let you decide if the US can make large engines with high performance and fuel mileage:
2007 Chevrolet Corvette C6- 6.0 liter V8 w/16 valves NA, 400 HP and 18 mpg city/ 28 highway.
2007 Chevrolet Corvette C6 Z06- 7.0 liter V8 w/16 valves NA, 505 HP and 16 mpg city/ 26 highway.
2007 Mercedes SL550- 5.5 liter V8 w/32 valves, 382 HP and 14 mpg city/ 22 highway.
2007 Mercedes SL65 AMG- 6.0 liter V12 w/ twin turbos, 604 HP and 13 mpg city/ 19 highway.
The base C6 Corvette is only .10 seconds slower than the SL65 AMG 0-60 MPH with four fewer cylinders, two fewer turbos and 204 fewer horsepower and if the AMG wasn't limited I doubt it could match the C6's 178 MPH top speed...
Back to the topic..
Edited by Trooper2 on Thursday 12th April 03:24
GreenV8S said:
GavinPearson said:
I have to say that I don't agree with this statement you've made "As far as cam / valve train wear goes, idling results in maximum contact load at peak lift. Increasing the revs reduces the peak lift contact load". I'd recommend you get the maths books out....
How do *you* think that the cam contact load at peak lift varies with revs, then?
This agrees with the performance cam instructions I've had. They all say "Do not let the engine idle when first fitted as thiis causes maximum loading on the lobes. Start engine & take to 2000RPM & leave it their for 20 minutes" "If the car starts to overheat then switch off & allow to cool"
tr7v8 said:
GreenV8S said:
GavinPearson said:
I have to say that I don't agree with this statement you've made "As far as cam / valve train wear goes, idling results in maximum contact load at peak lift. Increasing the revs reduces the peak lift contact load". I'd recommend you get the maths books out....
How do *you* think that the cam contact load at peak lift varies with revs, then?
This agrees with the performance cam instructions I've had. They all say "Do not let the engine idle when first fitted as thiis causes maximum loading on the lobes. Start engine & take to 2000RPM & leave it their for 20 minutes" "If the car starts to overheat then switch off & allow to cool"
The cam regrinders are dealing with a variety of engines that may or may not have design issues that cause inherent wear when modified.
It is far easier to publish a generic instruction that helps break in their component than deal with a multitude of conflicting explanations as to what may be going on.
GavinPearson said:
that daddy said:
I will continue to warm my car up in winter by starting it and then coming inside for breakfast.Quote Gavinpearson,,,,Hes american what do they know about conserving energy,plenty about waisting it though
GreenV8s i have watched this post closely,we have disagreed in the past on certain subjects, but i have read your posts on this subject and your spot on
GreenV8s i have watched this post closely,we have disagreed in the past on certain subjects, but i have read your posts on this subject and your spot onI suggest you retake your English O level and take a typing course.
Sorry Gavin,i dident know i had to be intelligent to go on this forum
that daddy said:
GavinPearson said:
that daddy said:
I will continue to warm my car up in winter by starting it and then coming inside for breakfast.Quote Gavinpearson,,,,Hes american what do they know about conserving energy,plenty about waisting it thoughGreenV8s i have watched this post closely,we have disagreed in the past on certain subjects, but i have read your posts on this subject and your spot on
GreenV8s i have watched this post closely,we have disagreed in the past on certain subjects, but i have read your posts on this subject and your spot onI suggest you retake your English O level and take a typing course.
Sorry Gavin,i dident know i had to be intelligent to go on this forum
Now who's lost their sense of humour...
Trooper2 said:
that daddy said:
GavinPearson said:
that daddy said:
I will continue to warm my car up in winter by starting it and then coming inside for breakfast.Quote Gavinpearson,,,,Hes american what do they know about conserving energy,plenty about waisting it thoughGreenV8s i have watched this post closely,we have disagreed in the past on certain subjects, but i have read your posts on this subject and your spot on
GreenV8s i have watched this post closely,we have disagreed in the past on certain subjects, but i have read your posts on this subject and your spot onI suggest you retake your English O level and take a typing course.
Sorry Gavin,i dident know i had to be intelligent to go on this forum
Now who's lost their sense of humour...Not at all,its just banter
Nah Trooper, it's not that I didn't believe you, it's more the notion that you can try to use the argument that because American gas guzzlers are (allegedly) more fuel efficient than European gas guzzlers, it somehow puts the Americans on a pedestal as gurus of fuel conservation that we should all aspire to. That's what made me laugh!
It's a bit like saying "hey, you Europeans could learn a thing or two about weight watching from the Americans because I've found a fat bloke in Europe who is fatter than a fat bloke I've found in the 'States"!
In any case (and I'm conscious of the fact that we're going off topic here!) the figures you have quoted are pretty meaningless in the context of fuel efficiency of engines. You need to quote "specific fuel consumption" for a variety of ENGINES. This will be quoted in lb/hp hour or kg/ kW hour. This shows the amount of fuel the engine needs to burn to produce a certain amount of work. It takes out all the other variables like transmission efficiency, car size, shape, weight, aerodynamic efficiency etc out of the equation so we can get back to what you're talking about. It is then a truer measure of "engine" efficiency. The trouble is, I've hardly ever seen this sort of information quoted.
It's a bit like saying "hey, you Europeans could learn a thing or two about weight watching from the Americans because I've found a fat bloke in Europe who is fatter than a fat bloke I've found in the 'States"!
In any case (and I'm conscious of the fact that we're going off topic here!) the figures you have quoted are pretty meaningless in the context of fuel efficiency of engines. You need to quote "specific fuel consumption" for a variety of ENGINES. This will be quoted in lb/hp hour or kg/ kW hour. This shows the amount of fuel the engine needs to burn to produce a certain amount of work. It takes out all the other variables like transmission efficiency, car size, shape, weight, aerodynamic efficiency etc out of the equation so we can get back to what you're talking about. It is then a truer measure of "engine" efficiency. The trouble is, I've hardly ever seen this sort of information quoted.
It's hard to judge the area under the curve by eye, and of course there's the assumption of whereabouts the cam loads do the most damage.
One would assume that the peak force seen at 2200rpm would vary dependent on the mass of the valve, whereas the load across the nose of the cam would vary with spring strength (and inversely with valve mass). Maybe there's no hard and fast rule, although the after market camshaft manufacturers seem to think there is.
One would assume that the peak force seen at 2200rpm would vary dependent on the mass of the valve, whereas the load across the nose of the cam would vary with spring strength (and inversely with valve mass). Maybe there's no hard and fast rule, although the after market camshaft manufacturers seem to think there is.
GavinPearson said:
I assume we can all read graphs.....
I think it clearly shows peak forces seen are greater at 2200 rpm than 800 rpm.
I think it clearly shows peak forces seen are greater at 2200 rpm than 800 rpm.
A bit like reading statistics
I read that the shoulders/ramp of the cam has marginally more load at 2200rpm than it sees on the nose at a 800rpm tick over, but significantly less load on the nose of the cam. Which is where wear will be seen and felt quickest (i.e. rounded off, less lift, less power)
Finally spoke to one of the valvetrain engineers at our place, and the requirement for new engines (especially gasoline engines) to get competitive performance but also improved emissions stability is that one must try and get as much air as possible in as short as time as possible. I.e. A lift profile like a square with lots of lift in a short duration to reduce valve overlap and sometimes allow for wider sweeping of a cam-phasing systems.
This trend has put horrific stress on cam acceleration and decceleration flanks, and durability has only been contained by studying what really happens and trying to shave unnecessary mass, improve machining, improve consistency and specification of materials, and taking advantage of improvements in oils and their additives. Some OEMs fudge the duty-cycle requirements in a quest to get improved performance and economy by their own evaluation of the question "How long do people really spend with their engine at 7000rpm over the engines lifetime?" The Japanese do tend to swing it towards the performance side!
Racing engines will have hammer cams over longer durations and possibly in a quest to reduce parasitic losses will probably try to reduce oil pressure and flow capacity to the bare minimum.
This trend has put horrific stress on cam acceleration and decceleration flanks, and durability has only been contained by studying what really happens and trying to shave unnecessary mass, improve machining, improve consistency and specification of materials, and taking advantage of improvements in oils and their additives. Some OEMs fudge the duty-cycle requirements in a quest to get improved performance and economy by their own evaluation of the question "How long do people really spend with their engine at 7000rpm over the engines lifetime?" The Japanese do tend to swing it towards the performance side!
Racing engines will have hammer cams over longer durations and possibly in a quest to reduce parasitic losses will probably try to reduce oil pressure and flow capacity to the bare minimum.
wheeljack said:
Finally spoke to one of the valvetrain engineers at our place, and the requirement for new engines (especially gasoline engines) to get competitive performance but also improved emissions stability is that one must try and get as much air as possible in as short as time as possible. I.e. A lift profile like a square with lots of lift in a short duration to reduce valve overlap and sometimes allow for wider sweeping of a cam-phasing systems.
This trend has put horrific stress on cam acceleration and decceleration flanks, and durability has only been contained by studying what really happens and trying to shave unnecessary mass, improve machining, improve consistency and specification of materials, and taking advantage of improvements in oils and their additives. Some OEMs fudge the duty-cycle requirements in a quest to get improved performance and economy by their own evaluation of the question "How long do people really spend with their engine at 7000rpm over the engines lifetime?" The Japanese do tend to swing it towards the performance side!
Racing engines will have hammer cams over longer durations and possibly in a quest to reduce parasitic losses will probably try to reduce oil pressure and flow capacity to the bare minimum.
This trend has put horrific stress on cam acceleration and decceleration flanks, and durability has only been contained by studying what really happens and trying to shave unnecessary mass, improve machining, improve consistency and specification of materials, and taking advantage of improvements in oils and their additives. Some OEMs fudge the duty-cycle requirements in a quest to get improved performance and economy by their own evaluation of the question "How long do people really spend with their engine at 7000rpm over the engines lifetime?" The Japanese do tend to swing it towards the performance side!
Racing engines will have hammer cams over longer durations and possibly in a quest to reduce parasitic losses will probably try to reduce oil pressure and flow capacity to the bare minimum.
So what did he say about cold idling for long periods of time?
David H said:
Seems to me that right or wrong; Gavin Pearson is a t
t.
Having seen many race engines fail due to improper cam bedding in, I am confident that bedding in a cam at around 2500-3000rpm dramatically reduces failure levels. How this transfers to normal everyday use I do not know.
t. Having seen many race engines fail due to improper cam bedding in, I am confident that bedding in a cam at around 2500-3000rpm dramatically reduces failure levels. How this transfers to normal everyday use I do not know.
Throwing about insults is pretty childish.
You are entitled to your opinion, and if the moderators tolerate it you can use whatever four letter words you can find in a dictionary to express that.
Having had a look at your website, my opinion is that you did a very nice job of cleaning, derusting and polishing your TVR.
Judging by your above comments your knowledge of the mathematics behind engineering and the subject of tribology is somewhat limited so it would be best to limit your comments to the merits of Brasso, Zymol, terry polishing cloths and discussions such as "Rust removal - abrasives or wire brushes?" or "Hammerite or powder coat?".
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