How do they...
Discussion
quote:
On another note whats the difference between a Wedge 4 ltr and a Chim/Griff and bigger (serpentine?). How did they manage to squeeze (if thats the right word) more power?
Ignoring the 390/420/450 which all have essentially hand built engines which were never the sme between cars and so on, you get more power because:
1. More capacity and there is no substitute for cubic inches.
2. The engine is designed to help get more fuel mixture into the engine to create the power. This means different cams, cyl heads, valves etc etc.
The 500 has some of this work done which works with the extra cc to give the power improvement. Beyond that starts getting very very expensive and while modest gains can be made at reasonable costs (3-5000 pounds), everything sky rockets beyond that.
A 4 litre V8 is typically around 200 bhps ish. the 5.2 litre V8 in the 520 is now nearly twice but the only thing that is common between the two engines i.e. has not been modified or enhanced in some way is the oil filler cap. Before you ask, the sump has been tinkered with to prevent oil surge.
Steve
www.tvrbooks.co.uk
What a great thread. Learning quite a lot.
Particularly interested in the configuration of the engines. What about the humble boxer (flat) variety. I once owned an Alfa 33 16v with the 1.7 flat-4. This was one of the most torquey engines I ever saw and delivered a great exhaust note as well, but vibrated like buggery.
And finally, lets not forget the rotary (Wankel) engine. I understand that these are incredibly efficient (less moving parts) and rev high, but why the fuel consumption?
Particularly interested in the configuration of the engines. What about the humble boxer (flat) variety. I once owned an Alfa 33 16v with the 1.7 flat-4. This was one of the most torquey engines I ever saw and delivered a great exhaust note as well, but vibrated like buggery.
And finally, lets not forget the rotary (Wankel) engine. I understand that these are incredibly efficient (less moving parts) and rev high, but why the fuel consumption?
The biggest problem with Wankels as I understand it is that they rely on seals to keep each arc-shaped chamber gas-tight but that, until recently, the materials available haven't been up to the job.
When one chamber blows through to the next, you lose pressure and efficiency and that, I believe, is one of the root causes of Wankel engines' high fuel consumption.
When one chamber blows through to the next, you lose pressure and efficiency and that, I believe, is one of the root causes of Wankel engines' high fuel consumption.
quote:
So why then, is the Griff 500 so god damn fast?? Somebody Please explain Bore/Stroke. Max RPM 6000. I thought Vee engine couild tolerate Higher RPMs. My 4 pot revs higher than that!!! Max Power 320bhp. Max Torque 320lb/ft! This doesn't make sense to me! Why does this engine have the Same amount of Torque as it does power. And Acceleration figures to confirm it?!?!?! Am I right in thinking that the Rover V8 uses a cam which can make use of torque at (maybe) the expense of power???
Another reason for the 'lower' rpm is the hydraulic tappets on the rover lump. Oil pressure in effect, fills the gap ( you know that expensive gap the ajp8/sp6 has to have adjusted every 6k ) between tappet & valve. But at higher revs the oil compresses. This is one reason why engines with hard tappets can rev higher. Also, as the stroke is the distance the piston travels for one rev. E.g. if a bike's stroke is about 50 mm, rover lump is about 94 mm. Thats nearly twice as bloody far the piston has to go for one rev.
The power/tourque measurement would have been taken at 5252 rpm. The reasoning for the magic 5252 rpm number is long and distinguished, but basicaly power = (tourque*revs)/5252 Which means power will always be greater than tourque above 5252 rpm & will always be less than tourque below 5252 rpm. So, power is a bit of a magic number, whereas tourque is real & you can feel it
Engine revs are often limited by other factors such as valve bounce, dizzy meltdown, excessive wear and so on. Rover V8 is no exception and spend enough money and they can rev to 7500 or more (but don't last too long).
Yes the Griff 500 is fast but in reality BHP it is only about 275 bhp and it tales off at around 5000 to 5500 but it has so much torque which is the ability to move things that its ability to accelerate does not rely on screaming the nuts off an engine to keep it in a narrow power band, outside which it doesn't have any power to do anything. As a result the driver has to keep shifting gears a lot and the end effect is a car that sounds good but can be slow as every gear change is about 0.7 seconds with no drive.
Compare this with a Griff or other V8 car where there is a wide power band and conversely the gearing can be abit more relaxed. The engine's torque now comes into play. It can pick up and accelerate but by and large has no narrow power band to worry about and can spend more time accelerating rather than changing gear.
It is this torque that catches many TVR first timers out though as it make it very very easy to spin the whgeels and loose traction and get the rear wheels overtaking the front.
Steve
www.tvrbooks.co.uk
Yes the Griff 500 is fast but in reality BHP it is only about 275 bhp and it tales off at around 5000 to 5500 but it has so much torque which is the ability to move things that its ability to accelerate does not rely on screaming the nuts off an engine to keep it in a narrow power band, outside which it doesn't have any power to do anything. As a result the driver has to keep shifting gears a lot and the end effect is a car that sounds good but can be slow as every gear change is about 0.7 seconds with no drive.
Compare this with a Griff or other V8 car where there is a wide power band and conversely the gearing can be abit more relaxed. The engine's torque now comes into play. It can pick up and accelerate but by and large has no narrow power band to worry about and can spend more time accelerating rather than changing gear.
It is this torque that catches many TVR first timers out though as it make it very very easy to spin the whgeels and loose traction and get the rear wheels overtaking the front.
Steve
www.tvrbooks.co.uk
I believe this has to do with compression ratio and overall engine size - as each gets bigger the engine braking effect gets stronger. In a big diesel it can be savage!
Does anyone know why sometimes it's really sharp when an engine's cold? eg in a 1.3 Daihatsu I once had, when the engine was very cold the engine braking could be very strong.
John.
Does anyone know why sometimes it's really sharp when an engine's cold? eg in a 1.3 Daihatsu I once had, when the engine was very cold the engine braking could be very strong.
John.
Is that not because the engine is so 'heavy'?! Moving 8 cylinders without (technically) using any more fuel. so the revs drop off viciously!!!
My 4 pot runs on for hours on 3rd or 4th! 5000 rpm in 4th ~90mph. Lift off and the speed drops below 60 about 3/4 mile later!!
Well, at least it does when the clutch works
My 4 pot runs on for hours on 3rd or 4th! 5000 rpm in 4th ~90mph. Lift off and the speed drops below 60 about 3/4 mile later!!
Well, at least it does when the clutch works
Engine power is a product of just sooo many variables, its perhaps not easy for someone to put their finger on a specific 'part' which is going to light the tires at dab of the throttle.
Do you know what effect a long bar on your ratchet socket handle does?? It allows you to turn the bolt easier, more 'torque'. So in effect a long stroke engine will have more torque. BUT the effect of intake runner design, camshaft design, head design etc etc make the characteristics of the engine. And dont forget the GEARBOX. The gear ratios also play an important part in how the power gets to the ground. They are mearly a torque multiplier.
Also if the engine revs higher, it aint gonna make more power. This is because of the total design of the engine. Example :
I have a Chevrolet V8, 350 cubes. Goes great. Pulls well down low. Can start of in 3rd gear!!!! Runs out of puff at 5500rpm. A great all round runer - Strip engine down......
1/ Change heads, big valves (2.02-1.6) raise compression ratio - now 10.25;1
2/ Change camshaft, wonky idle at 900rpm, cant take off in 3rd anymore.
3/ Change intake manifold and carburation - fuel consumption suffered
4/ New exaust system
5/ General stuff, more reliability, new H-beam rods, halve weight of flywheel, oil pump and cooler, fast bleed hydraulic lifters, rebalance assembly,higher pressure fuel pump
6/ Change gearbox, slightly higher final drive
Put back in car.
Who cares about starting in 3rd. The tires now spin on the change into 3rd at 70 mph - dry road.
Had to add rev limiter to ignition system - engine wont stop reving, limiter now set at 7300 rpm.
At 5500 rpm the old engine had all but plateaued. Now its just another number as the rev counter rockets past this - IN ALL GEARS !!!
Had to add better head rest to seats. Got a flat spot on the back of my head from having it pushed into the seat at every prod of the throttle over 3000 rpm.
Surgery was required to remove the permanent grin from my face.
So where is this leading ?? - to the gas station and the tyre shop ?? well yes, but its an example of how engine components affect the speed/power relationship in your cars.
Their ain't no substitute for cubic inches !!!!
Do you know what effect a long bar on your ratchet socket handle does?? It allows you to turn the bolt easier, more 'torque'. So in effect a long stroke engine will have more torque. BUT the effect of intake runner design, camshaft design, head design etc etc make the characteristics of the engine. And dont forget the GEARBOX. The gear ratios also play an important part in how the power gets to the ground. They are mearly a torque multiplier.
Also if the engine revs higher, it aint gonna make more power. This is because of the total design of the engine. Example :
I have a Chevrolet V8, 350 cubes. Goes great. Pulls well down low. Can start of in 3rd gear!!!! Runs out of puff at 5500rpm. A great all round runer - Strip engine down......
1/ Change heads, big valves (2.02-1.6) raise compression ratio - now 10.25;1
2/ Change camshaft, wonky idle at 900rpm, cant take off in 3rd anymore.
3/ Change intake manifold and carburation - fuel consumption suffered
4/ New exaust system
5/ General stuff, more reliability, new H-beam rods, halve weight of flywheel, oil pump and cooler, fast bleed hydraulic lifters, rebalance assembly,higher pressure fuel pump
6/ Change gearbox, slightly higher final drive
Put back in car.
Who cares about starting in 3rd. The tires now spin on the change into 3rd at 70 mph - dry road.
Had to add rev limiter to ignition system - engine wont stop reving, limiter now set at 7300 rpm.
At 5500 rpm the old engine had all but plateaued. Now its just another number as the rev counter rockets past this - IN ALL GEARS !!!
Had to add better head rest to seats. Got a flat spot on the back of my head from having it pushed into the seat at every prod of the throttle over 3000 rpm.
Surgery was required to remove the permanent grin from my face.
So where is this leading ?? - to the gas station and the tyre shop ?? well yes, but its an example of how engine components affect the speed/power relationship in your cars.
Their ain't no substitute for cubic inches !!!!
Also if the engine revs higher, it ain't gonna make more power. This is because of the total design of the engine. IF this is true, why is your rev limiter set at 7300 RPM's, instead of the original 5500 ? Surely you were speaking of the stock engine only.
I think you will find that your transmission does a "little" more that just multiply torque. I believe that the ratios also keep the engine in it's "proper" RPM (power) band. If the RPM drop between gears is to great, the engine falls out of it's usable power band, and that is very important, also if the ratios are to close you are not using all of the available power band.
You didn't state very clearly if the final drive ratio is lower numerically in the transmission ( T-5 or T-56 overdrive maybe ? ) or were refering to the rear axle assembly 3:23's versus 4:10's.
#1. 2.02/1.60 heads...open or closed chambers ? With a stock 4.00" bore, intake valves are shrouded at outer edge, so extra money spent for them is wasted, as there isn't any flow gain, and in some cases can actually be less than 1.94" valve heads at lower lift figures.
#2. Wonky at 900 RPM....even with bleed down hydralic lifters ? Usually this type of lifter knocks off 10-20 degrees of duration under 3500 RPM, depending on manufacturer. They also can be used as a crutch for an engine where too big (duration ) cam has been bought, and engine has lost a lot of bottom end power. Cubic inches can only cover up for so much duration.
#3. Fuel consumption ? Spinning the engine to 7300 sounds good, wears it out faster, uses more fuel. On the other hand, if the cam bought was a real wicked stick, with enough duration to rattle windows for 3 blocks around, then you must have to rev it up to about your 3500-4000 RPM bleed up point just to develope any sort of torque at all. Every time you jiggle the pedal, you are squirting dead dinosauers into the engine, wasting fuel.
There is a substitute for cubic inches..some will say MORE ! I prefer to say compatable parts, that work together or complement each other, so that the power increase is available now-right away-as soon as you stomp on that bad boy, because as someone else is reving to find his power band, or to just keep it from blowing back through the carb(s), the other person is GONE, period !
On camshaft selection, the rule of thumb is : Find the RPM range that the engine is operated in the MOST, then pick one for that range or just a tad higher. So you have 10,000 HP at 10,000 RPM, exactly when are you going to see this....pulling out of garage maybe ?
A little planning goes a long way, and the camshaft is the heart of your engine.....it will make you or break you in the power department, like no other part can.
I think you will find that your transmission does a "little" more that just multiply torque. I believe that the ratios also keep the engine in it's "proper" RPM (power) band. If the RPM drop between gears is to great, the engine falls out of it's usable power band, and that is very important, also if the ratios are to close you are not using all of the available power band.
You didn't state very clearly if the final drive ratio is lower numerically in the transmission ( T-5 or T-56 overdrive maybe ? ) or were refering to the rear axle assembly 3:23's versus 4:10's.
#1. 2.02/1.60 heads...open or closed chambers ? With a stock 4.00" bore, intake valves are shrouded at outer edge, so extra money spent for them is wasted, as there isn't any flow gain, and in some cases can actually be less than 1.94" valve heads at lower lift figures.
#2. Wonky at 900 RPM....even with bleed down hydralic lifters ? Usually this type of lifter knocks off 10-20 degrees of duration under 3500 RPM, depending on manufacturer. They also can be used as a crutch for an engine where too big (duration ) cam has been bought, and engine has lost a lot of bottom end power. Cubic inches can only cover up for so much duration.
#3. Fuel consumption ? Spinning the engine to 7300 sounds good, wears it out faster, uses more fuel. On the other hand, if the cam bought was a real wicked stick, with enough duration to rattle windows for 3 blocks around, then you must have to rev it up to about your 3500-4000 RPM bleed up point just to develope any sort of torque at all. Every time you jiggle the pedal, you are squirting dead dinosauers into the engine, wasting fuel.
There is a substitute for cubic inches..some will say MORE ! I prefer to say compatable parts, that work together or complement each other, so that the power increase is available now-right away-as soon as you stomp on that bad boy, because as someone else is reving to find his power band, or to just keep it from blowing back through the carb(s), the other person is GONE, period !
On camshaft selection, the rule of thumb is : Find the RPM range that the engine is operated in the MOST, then pick one for that range or just a tad higher. So you have 10,000 HP at 10,000 RPM, exactly when are you going to see this....pulling out of garage maybe ?
A little planning goes a long way, and the camshaft is the heart of your engine.....it will make you or break you in the power department, like no other part can.
Interesting reading Motorman. If you will note, virtually all of the engine components have been changed. Firstly Why a 7300 rpm cutout??
Well because the engine has a realistic redline of 6500. This is governed by the valvetrain and more importantly the valve springs. This is the limit set by the manufacturer of the heads/springs. The extra 800 rpm is for inaccuracies of my rev counter, my reaction time to shift at 6500, and missed shifts causing the engine to perhaps want to 'over-rev'.
The engine had heads on it which restricted the airflow therefore the potential to make more power, at higher revs. The heads had the smallest valves that Chevrolet make for an engine 1.71- 1.5's. This was good for low end torque which was evident from being able to take off in 3rd gear and from the dyno printouts. The intake manifold was also designed to work only up to around 5500.
The gearbox query you note is too worthy of comment. As much as the gearbox is a torque multiplier, yes the ratios should be chosen to keep the the engine in its maximum torque vs hp range. The gearbox ratios I have are a refection of this theory. When I view the dynomometer printouts I see that I have 348 ft/lbs @ 2000 rpm up to 464 ft/lbs @ 4500, this drops to 401 @ 6000. The ratio percentage drop between gears is 39% 1st-2nd, 33% 2nd-3rd, 26% 3rd-4th, 21% 4th-5th.
Therefore if I changed gear at 6000 I would drop back, in every gear to be well inside a maximum torque range. Where in this case the 1st gear change would put me back to 3660 rpm which at which point the engine develops 430 ft/lb and 290 hp.
Interesting to note though, at 4500 the engine makes its most torque 464 ft/lb and 397 hp and at 6000 makes 458hp and 401ft/lbs. The old engine at the same speeds made at 4500 333ft/lb and 286 hp and at 6000, 207ft/lb and 237 hp. BUT at 2000 the old engine made 368ft/lb vs the new one of 340ft/lb.
My final drive ratio was changed from 3.89:1 to 3.44:1.
The heads I used on the new engine are TrickFlow Twisted Wedge units. Sure the valves are larger (4%on the intake) but it is the total head design which allows better breathing at higher rpms. Manufacturing claims allow for more potential in power making and I do believe this to be the case, since I have also had the Edelbrock RPM series heads on another engine.
When I mean wonky at idle, I mean a little rough, you could still sit a glass of water on the engine and it not fall off, but you couldnt balance a pencil on it (as did Ford's engineers during the design of the Model T engine). The different camshaft profile took care of this. For your information the cam profile is @.050, 234I, 244E, Lobe centre 112, Lift .488I, .508E with 1.5:1 rocker arms. Manufacturers spec (Crane) is to give power from 3000-6500, and I believe this to be achieved in my engine.
Your next point about fuel consumption, well I like my foot, and it likes gravity ! so thats where its at. My carburation is 4 x 48 DCOE webers. Every time you dab the throttle, there are 8 accelerator pumps doing a little squirt! But hey, gas it cheap here. Your point about reving to 7300 was answered earlier. I dont rev it there, 6500 is fine if I even need to go that far - in fact engine power at 7000 is 438 hp and 329ft/lb, so waste of time doing it. The 7300 was for the rev limiter to cut in.
The useable power band in the new engine is from 3000 - 6000 rpm. In this range at no time does the torque drop below 400ft/lbs. At 2000 I have 133hp and 348ft/lb, more than enough to get out of the garage or even pull the skin off all the worlds rice puddings at once. The old engine made its power from off idle to 2500@371ft/lb, from at which point the power then started to drop off. So all in all the extra power has been utilised further up the power range from 3000-6000 and not from idle to 2500. So in a car that weighs 2600lbs you cant complain about that!
Well because the engine has a realistic redline of 6500. This is governed by the valvetrain and more importantly the valve springs. This is the limit set by the manufacturer of the heads/springs. The extra 800 rpm is for inaccuracies of my rev counter, my reaction time to shift at 6500, and missed shifts causing the engine to perhaps want to 'over-rev'.
The engine had heads on it which restricted the airflow therefore the potential to make more power, at higher revs. The heads had the smallest valves that Chevrolet make for an engine 1.71- 1.5's. This was good for low end torque which was evident from being able to take off in 3rd gear and from the dyno printouts. The intake manifold was also designed to work only up to around 5500.
The gearbox query you note is too worthy of comment. As much as the gearbox is a torque multiplier, yes the ratios should be chosen to keep the the engine in its maximum torque vs hp range. The gearbox ratios I have are a refection of this theory. When I view the dynomometer printouts I see that I have 348 ft/lbs @ 2000 rpm up to 464 ft/lbs @ 4500, this drops to 401 @ 6000. The ratio percentage drop between gears is 39% 1st-2nd, 33% 2nd-3rd, 26% 3rd-4th, 21% 4th-5th.
Therefore if I changed gear at 6000 I would drop back, in every gear to be well inside a maximum torque range. Where in this case the 1st gear change would put me back to 3660 rpm which at which point the engine develops 430 ft/lb and 290 hp.
Interesting to note though, at 4500 the engine makes its most torque 464 ft/lb and 397 hp and at 6000 makes 458hp and 401ft/lbs. The old engine at the same speeds made at 4500 333ft/lb and 286 hp and at 6000, 207ft/lb and 237 hp. BUT at 2000 the old engine made 368ft/lb vs the new one of 340ft/lb.
My final drive ratio was changed from 3.89:1 to 3.44:1.
The heads I used on the new engine are TrickFlow Twisted Wedge units. Sure the valves are larger (4%on the intake) but it is the total head design which allows better breathing at higher rpms. Manufacturing claims allow for more potential in power making and I do believe this to be the case, since I have also had the Edelbrock RPM series heads on another engine.
When I mean wonky at idle, I mean a little rough, you could still sit a glass of water on the engine and it not fall off, but you couldnt balance a pencil on it (as did Ford's engineers during the design of the Model T engine). The different camshaft profile took care of this. For your information the cam profile is @.050, 234I, 244E, Lobe centre 112, Lift .488I, .508E with 1.5:1 rocker arms. Manufacturers spec (Crane) is to give power from 3000-6500, and I believe this to be achieved in my engine.
Your next point about fuel consumption, well I like my foot, and it likes gravity ! so thats where its at. My carburation is 4 x 48 DCOE webers. Every time you dab the throttle, there are 8 accelerator pumps doing a little squirt! But hey, gas it cheap here. Your point about reving to 7300 was answered earlier. I dont rev it there, 6500 is fine if I even need to go that far - in fact engine power at 7000 is 438 hp and 329ft/lb, so waste of time doing it. The 7300 was for the rev limiter to cut in.
The useable power band in the new engine is from 3000 - 6000 rpm. In this range at no time does the torque drop below 400ft/lbs. At 2000 I have 133hp and 348ft/lb, more than enough to get out of the garage or even pull the skin off all the worlds rice puddings at once. The old engine made its power from off idle to 2500@371ft/lb, from at which point the power then started to drop off. So all in all the extra power has been utilised further up the power range from 3000-6000 and not from idle to 2500. So in a car that weighs 2600lbs you cant complain about that!
lawrence1....first let me state that whenever I address a/this forum, it is in a generalization mode, as I never intend to shove a stick in anyones eye, or choice of parts. The overriding factor "again" is consumer knowledge, the more knowledge we have on file, the better choices we can intelligently make. I have made errors in parts selection, so have others..none of us need to/care to be reminded of this...AMEN.
1.Redline..valve springs are rated/spec's by their open/closed lengths, and the amount of psi they exert before coil bind occurs, and the maximum amount of lift before coil bind occurs. Psi does have a bearing on how well the weight of valvetrain is controlled, but by the same token if you have a lighter assembly than your neighbor, yours will "redline" higher than his, but not because of a rpm limit designed into the springs.Possibly you were mislead by salesman into thinking the springs came with a "tag" stating: max. rpm XXXX. I don't know about you, but my engine definately wants to, and will, over-rev when I miss a shift/gear....but I'm affraid my heart over-revs faster than the engine ever could !
2. What a fantastic choice for heads ! These are the only 23 degree heads that are NOT shrouded, due to their shape. See again a general statement on my part, concerning heads being shrouded-no stick intended ! Can be ported to flow great figures and their shape gives super swirl/mix to fuel. We don't even have to discuss what the improved breathing on the I/E ports will do for you.
3. At first I thought car would like 3:89 gears better, RPM drop on shifts not as great, would keep engine in "sweet spot" of torque curve (middle), BUT after seeing you only drag around 2600#, I'm not too sure. Would be interesting to try, if gears/rear still laying around.
4. "Dead dinosauers"...I also like my toes, and gravity tends to keep on pulling my foot towards floor also. Got to the point had to hook strap to my leg to keep toes out of fan ! Fuel consumption is putting it mildly, with over 2200 cfm. of flow ! Might even be too much, like having 2-1050 Dominators on it. Glad fuel is cheap- can see the word economy isn't in your vocabulary !
5. Don't do that to my puddin', I like the skin ! Didn't mean YOUR car couldn't get out of the garage- the 10,000 car couldn't ! Example only-again
6. " Interesting to note though " DEPT..we get to the engines heart dept...camshaft choices..you have a really mild cam in that monster, considering the induction choice, and adding in the fact that you use v/dur. lifters, and wide lobe centers also. Should you have changed over to 6.0" rods, which many do, the following will apply even more. PLEASE keep in mind that these are my thoughts only....no sticks intended, and is meant to increase your and others knowledge on possible camshaft selections. First my mention of longer rods and why.. piston stays at TDC/BDC for longer time (dwell). What does this do ? Longer at TDC, allows fuel more time to completely burn-thus more bang for the buck. Longer at BDC, gives camshaft more time to completely fill cylinder, and by the same token remove gasses when combustion process is finished. We won't go into the leverage factors here. It would seem that you are puzzled by the comparisons between the old vs. new torque/hp figures. While your choice of induction systems is fantastic, and sheer delight to the eyes it's kinda overkill, despite its fantastic adjustability/tuneability. More of an upper RPM induction system (6-8500). Coupled with the fact that cam is more bottom end oriented, you might find a mismatch here. That's why engine makes max. torque at 4500, horsepower at 6000. Have 2200 plus cfm of air trying to enter, cam is saying-no ! 112 degree ctrs. give better bottom end power/driving ability, but 108 centers will utilize that induction system better, especially when the duration is greatly increased. With v/dur. lifters, can have best of both worlds so to speak. 290-300 degree duration cams with v/dur. lifters have about 260-270 degrees duration at IDLE. Fairly smooth, will develope good vacuum if needed for anything, but the power band will be raised to an area where that induction system can really be used when lifters pump-up, while still retaining some semblence of being streetable. Of course this all depends if your heads can flow any kind of respectable cfm at higher speeds also.
1.Redline..valve springs are rated/spec's by their open/closed lengths, and the amount of psi they exert before coil bind occurs, and the maximum amount of lift before coil bind occurs. Psi does have a bearing on how well the weight of valvetrain is controlled, but by the same token if you have a lighter assembly than your neighbor, yours will "redline" higher than his, but not because of a rpm limit designed into the springs.Possibly you were mislead by salesman into thinking the springs came with a "tag" stating: max. rpm XXXX. I don't know about you, but my engine definately wants to, and will, over-rev when I miss a shift/gear....but I'm affraid my heart over-revs faster than the engine ever could !
2. What a fantastic choice for heads ! These are the only 23 degree heads that are NOT shrouded, due to their shape. See again a general statement on my part, concerning heads being shrouded-no stick intended ! Can be ported to flow great figures and their shape gives super swirl/mix to fuel. We don't even have to discuss what the improved breathing on the I/E ports will do for you.
3. At first I thought car would like 3:89 gears better, RPM drop on shifts not as great, would keep engine in "sweet spot" of torque curve (middle), BUT after seeing you only drag around 2600#, I'm not too sure. Would be interesting to try, if gears/rear still laying around.
4. "Dead dinosauers"...I also like my toes, and gravity tends to keep on pulling my foot towards floor also. Got to the point had to hook strap to my leg to keep toes out of fan ! Fuel consumption is putting it mildly, with over 2200 cfm. of flow ! Might even be too much, like having 2-1050 Dominators on it. Glad fuel is cheap- can see the word economy isn't in your vocabulary !
5. Don't do that to my puddin', I like the skin ! Didn't mean YOUR car couldn't get out of the garage- the 10,000 car couldn't ! Example only-again
6. " Interesting to note though " DEPT..we get to the engines heart dept...camshaft choices..you have a really mild cam in that monster, considering the induction choice, and adding in the fact that you use v/dur. lifters, and wide lobe centers also. Should you have changed over to 6.0" rods, which many do, the following will apply even more. PLEASE keep in mind that these are my thoughts only....no sticks intended, and is meant to increase your and others knowledge on possible camshaft selections. First my mention of longer rods and why.. piston stays at TDC/BDC for longer time (dwell). What does this do ? Longer at TDC, allows fuel more time to completely burn-thus more bang for the buck. Longer at BDC, gives camshaft more time to completely fill cylinder, and by the same token remove gasses when combustion process is finished. We won't go into the leverage factors here. It would seem that you are puzzled by the comparisons between the old vs. new torque/hp figures. While your choice of induction systems is fantastic, and sheer delight to the eyes it's kinda overkill, despite its fantastic adjustability/tuneability. More of an upper RPM induction system (6-8500). Coupled with the fact that cam is more bottom end oriented, you might find a mismatch here. That's why engine makes max. torque at 4500, horsepower at 6000. Have 2200 plus cfm of air trying to enter, cam is saying-no ! 112 degree ctrs. give better bottom end power/driving ability, but 108 centers will utilize that induction system better, especially when the duration is greatly increased. With v/dur. lifters, can have best of both worlds so to speak. 290-300 degree duration cams with v/dur. lifters have about 260-270 degrees duration at IDLE. Fairly smooth, will develope good vacuum if needed for anything, but the power band will be raised to an area where that induction system can really be used when lifters pump-up, while still retaining some semblence of being streetable. Of course this all depends if your heads can flow any kind of respectable cfm at higher speeds also.
Hey Motorman.
The induction system whilst having the capability of flowing around 2200 cfm, you forget that the induction is based on individual runners. I have an 8 cylinder engine. Each cylinder does not suck from a common plenum chamber. Thus each cylinder only has a maximum of 275 cfm to draw from. This makes for a very high velocity flow through the venturi.
Take for example a 750 cfm 4-barrel Holley on a 2 plane manifold. Each cylinder will be able to suck a maximum of 375 cfm. This will offer slower air velocities thru the venturis at low revs, therefore leaner mixture. SO in effect I will have superior power down low with the Webers because of the strong signal produced by having high air velocities in the individual runners. Whereas the Holley will produce superior power in the upper rev range where the Weber carbs cannot flow the same air volume. EG: webers will only flow a maximum of 275cfm - Holley 375cfm. It gets even worse with a single plane manifold, eg: Edelbrock Victor Junior - with the 750 carb each cylinder has the ability to draw 750cfm. Velocity is very slow at low revs and only will power become available from high revs when it can have faster air flow.
So the engine will run very lean down low with a single plane manifold. A smaller carb on this will work wonders though.
The 2 plane will work ok with the 750, but I have found that a 650 is a better choice.
Moral of story? If I want to get excessive power at high revs .. 7000 > use a single plane manifold with a 750 4-barrel or there abouts carby. (experiment here)
If I want superior low end (0 - 6000) the Webers (or Dellortos) are the best choice. Or perhaps the 2 plane with a 600 4-barrel, but even that still has lower velocities at 300cfm per cylinder.
....... and we wont even get into reversion pulses etc that are power robbing, that you get from common plenums.
As you said, its all an open learning experience.
The induction system whilst having the capability of flowing around 2200 cfm, you forget that the induction is based on individual runners. I have an 8 cylinder engine. Each cylinder does not suck from a common plenum chamber. Thus each cylinder only has a maximum of 275 cfm to draw from. This makes for a very high velocity flow through the venturi.
Take for example a 750 cfm 4-barrel Holley on a 2 plane manifold. Each cylinder will be able to suck a maximum of 375 cfm. This will offer slower air velocities thru the venturis at low revs, therefore leaner mixture. SO in effect I will have superior power down low with the Webers because of the strong signal produced by having high air velocities in the individual runners. Whereas the Holley will produce superior power in the upper rev range where the Weber carbs cannot flow the same air volume. EG: webers will only flow a maximum of 275cfm - Holley 375cfm. It gets even worse with a single plane manifold, eg: Edelbrock Victor Junior - with the 750 carb each cylinder has the ability to draw 750cfm. Velocity is very slow at low revs and only will power become available from high revs when it can have faster air flow.
So the engine will run very lean down low with a single plane manifold. A smaller carb on this will work wonders though.
The 2 plane will work ok with the 750, but I have found that a 650 is a better choice.
Moral of story? If I want to get excessive power at high revs .. 7000 > use a single plane manifold with a 750 4-barrel or there abouts carby. (experiment here)
If I want superior low end (0 - 6000) the Webers (or Dellortos) are the best choice. Or perhaps the 2 plane with a 600 4-barrel, but even that still has lower velocities at 300cfm per cylinder.
....... and we wont even get into reversion pulses etc that are power robbing, that you get from common plenums.
As you said, its all an open learning experience.
Arghhhh ! Yes an open learning lesson. Sorry for the delay on responce, had trouble pulling head from ass, spent yesterday (Sunday), kicking same lower body part. Talk about gross mental mistakes ( read brain-fart ), have Hilborn injected I/R motor myself (S/B 377 (gas) and 410 Donovan (alky) ). Not much more to say on that subject, better forgotten.
Started with flatheads/Jimmy 6's, so must be old age catching up with me, for this is the second time I have been caught in this type of error, in a very short period of time. No excuse, but when you begin to doubt yourself ?
That was a super explanation of intake types, if you are not instucting this, I think you missed your calling. Very well put, so easy a rock could understand !
Shame you are so far away, car must really be a treat to see, definately to ride in...as we say " Acoustical or Sensory Overload Area "... Alan
Started with flatheads/Jimmy 6's, so must be old age catching up with me, for this is the second time I have been caught in this type of error, in a very short period of time. No excuse, but when you begin to doubt yourself ?
That was a super explanation of intake types, if you are not instucting this, I think you missed your calling. Very well put, so easy a rock could understand !
Shame you are so far away, car must really be a treat to see, definately to ride in...as we say " Acoustical or Sensory Overload Area "... Alan
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