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Forced Induction Vs. N/ARobinxr4i
@robinxr4i
Club Retro Rides Member 143
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Sept 19, 2007 15:18:13 GMT
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In the "saab engine potential" thread posted by qwerty (good work that man )......... ......Popuptoaster said along the lines that a standard Sierra RS Cosworth is slower than a Sierra with a 2.9 24v Cosworth (Granada enigne) transplant and that if you compare a turbocharged engine car with an N/A one producing the same power that the N/A engined car would be quicker. Is this expressly true and can it ever be proved or disproved? plus do supercharged engine have the same problem? Personally I love turbos and boost, its a cheap (and possibly cheats) way of producing serious power from an otherwise unspectacular engine! After my 480 Turbo I expect every car to get a massive wave of power as the engine reaches 3,000 rpm Anyway disscuss ;D
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Sierra - here we go again! He has an illness, it's not his fault.
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Sept 19, 2007 15:29:20 GMT
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if you compare a turbocharged engine car with an N/A one producing the same power that the N/A engined car would be quicker. Is this expressly true and can it ever be proved or disproved? There are so many variables that I don't see how you can prove this one way or another? I like either, depending on the character of the car. If you've got something sporty with a close ratio box then a turbo can feel great, if you got something wafty then you really need a big wave of torque and no more than 2 gears.
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starionturbo
Part of things
Is planning mental turbo action MU HUH HUH!!!
Posts: 528
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Sept 19, 2007 15:36:18 GMT
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Well If both engines produce the same BHP the forced induced one will produce more torque, more torque = quicker Acceleration.......
Oh and supercharger's don't suffer with Lag, it's belt driven and boost is constant and pretty much instant BUT it does sap engine power. Turbo's Are exhaust driven and as such are "FREE" horsepower but they need to spool up hence the lag, but there is ways round this like the anti lag systems found on Cosworth's and specifically cut impeller wheels.
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Forced Induction Vs. N/ARobinxr4i
@robinxr4i
Club Retro Rides Member 143
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Sept 19, 2007 15:38:36 GMT
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Well If both engines produce the same BHP the forced induced one will produce more torque, more torque = quicker Acceleration....... Thats what I thought. Especially with modern engine as they has very low lag and a turbocharger can provide so much mid range torque
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Sierra - here we go again! He has an illness, it's not his fault.
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mowzer
Part of things
Posts: 618
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Sept 19, 2007 15:40:19 GMT
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Having been lucky enough to have owned all 3 options over the years I like all 3 of them for different reasons
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starionturbo
Part of things
Is planning mental turbo action MU HUH HUH!!!
Posts: 528
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Sept 19, 2007 15:41:11 GMT
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Well off the line my Starion gets beat by saxo's (unless i cain the clutch) But once i hit 3000rpm and the boost and cam come in it's all "hold on, smile and wave as you go past ;D)
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Sept 19, 2007 16:16:40 GMT
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Well If both engines produce the same BHP the forced induced one will produce more torque, more torque = quicker Acceleration....... Not always true, and even when it is its only true when the turbo has spun up to speed. Get over onto turbosport and look the topic up, we argued for ages until the real race car drivers came on, several of them have had N/A and turbo engines in the same car as they change classes or rules change and they all have known lap times around known circuits. There are even drivers who have said that fitting a MORE powerfull turbo engine slowed them down untill they got a handle on the different way they had to drive the cars on various circuits. There are variables, but a big N/A engine making the same power as a smaller turbo engine will win round a track usually. don't forget on a race track there are cars in the way, so its not just torque and power that win races its how predictable your car is as far as getting the power down smoothly and how well you can pull out of the corners, also a turbo and all its gumph can add a fair bit of weight at the front of a car so effect its handling. Different story on a drag strip but we all know thats not real racing. Not many circuit racers use engine driven chargers for some reason, I guess its because the benefit of low down power is outweighed by the high RPM losses which is where most race engines spend all their time? don't get me wrong, I like turbo's, my 24v will probably get a couple eventually.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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Sept 19, 2007 16:22:29 GMT
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Horses for courses.
A Mustang with a howling 500 bhp 2.0 turbo? Nah.
A Skyline with a 500 bhp rumbly V8? Nah.
no idea on the science of which is better and no idea how you'd exterminate the variables but some cars suit turbo, some supercharger, and some N/A. Kinda fits with the style of car.
As for lag - I don't think its as much of an issue as people seem to think.
People often confuse lag with the point at which boost kicks in. Not the case.
If you put your foot down then wait a while til you get to 2500 rpm and then the turbo spools up and you rocket, thats not lag, thats just the boost threshold.
IE an N/A might have just the same properties, you might put your foot down and not get anything until 2500 rpm but you wouldnt say your N/A suffers from lag, you'd say it wasnt in the power band.
Lag specificaly is where you're over the boost threshold and then put your foot down and it hesitates before accelerating - this is the time it takes to expel the gases from the engine, spin the turbo, and fill the intercooler and all the pipes with air before making positive pressure and feeling the turbo 'kick in yo' and fun begins.
the two are very often confused and hence turbo cars get blamed for having lag when really its just not yet reached the boost threshold.
My Starion suffers from pretty much no lag whatsoever. It does, however, have to reach the boost threshold to feel the effects of the turbo. But it's not lag.
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Sept 19, 2007 16:26:32 GMT
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my 24v as standard don't come into its power band untill it hits 3200rpm but even below this its still making about 75% of its power and torque, its starts from about 1000rpm, thats that advantage over a smaller turbo engine, your smaller engines off boost performance is worse than my big engines off cam performance.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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Sept 19, 2007 16:27:51 GMT
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also a turbo and all its gumph can add a fair bit of weight at the front of a car so effect its handling. Surely Turbo + Intercooler + some pipes doesnt weigh as much as an extra cylinder head? I'm not arguing cos I'll admit you know more than me. It just doesn't seem that they would. I know for a fact mine doesn't (though they are small), the intercooler and turbo don't weigh much and the pipes weight is negligable. Perhaps on a crazy big turbo car with huge cooler but even then, you'd have to be running a big V8 to match BHP with said car, meaning thats a whole cylinder head and half an engine block of difference which would weigh more surely? Also my car makes 230ftlb torque @ approx 3000 rpm but does start making it a lot lower. I've not looked at my rr report for a while so cant remember.
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Last Edit: Sept 19, 2007 16:31:48 GMT by wickedbad
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Sept 19, 2007 16:39:37 GMT
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my 24v as standard don't come into its power band untill it hits 3200rpm but even below this its still making about 75% of its power and torque, its starts from about 1000rpm, thats that advantage over a smaller turbo engine, your smaller engines off boost performance is worse than my big engines off cam performance. This is an old report - diagnosis from when car was broken so ignore the numbers but look at the curve (its the same now but moved up the page ;D ) torque @ 1600 rpm (where it starts) = 140 ftlb torque @ 3300 rpm (max) = 185ftlb maths tells me (140/185) = 76% so my turbo car seems to perform the same as your N/A in terms of making 76% of its power low down?
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Last Edit: Sept 19, 2007 16:40:59 GMT by wickedbad
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Sept 19, 2007 16:40:09 GMT
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I'm not just talking about big V8's or V6's I just happen to be using mine as an example, a 1.6 litre 4 pot turbo could be making the same power as a 2.4 litre 4 pot for example, in which case the turbo engine would be heavier. I don't have a RR figure for my 24v as yet but basically under 3200rpm the behave pretty much the same as the old 12v with pretty much the same power and torque, but check out the one from my old 2.8, it wasn't a big bhp engine, MAX torque (196/ft) was at about 2600rpm, cant see a 140bhp turbo engine doing THAT! Looking at both graphs, i had less power all through but more torque low down, which should mean that had my engine would be better out of corners, off th line or had i been caught in the wrong gear, you would have whistled passed eventually though, given enough room to get round me.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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Sept 19, 2007 16:45:50 GMT
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but its not as far behind as you think, and thats just my broken car.
At 2600 mines still making 83% of its torque.
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Sept 19, 2007 16:48:58 GMT
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mines making 150lb/ft before your graph even starts and I'm down on overall power and torque, add another 10 or 15% to catch you up and mine would be even better.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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Hirst
Posted a lot
This avatar is inaccurate, I've never shaved that closely
Posts: 3,930
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Sept 19, 2007 16:52:20 GMT
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The strongest application of a turbo is that it allows a small, lightweight engine to have the same power as a huge, heavy one. It also allows for massive power increases (provided the engine is strong enough to take it) which an NA engine would only be able to match by increasing the size.
As an extreme example, in Stage 2 form, the Daihatsu Storia X4 runs a 713cc engine with around 200hp. The biggest engine you can easily fit to said car is a 1.3, which it would be extremely difficult to get that sort of power out of without boost. You would also have the added disadvantage of more weight on the front.
I reckon as engine comparisons go, a 500hp NA engine will probably be quite a bit better than a 500hp turbo engine as it should have all the power on tap with no lag, etc. But fitted to a car it would inevitably be bigger and heavier. Obviously turbo engines have their compromises, but in the real world you can't shove 7 litre engines into ordinary sized cars and expect them to handle well.
Verdict: It all depends on the car and engine!
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Sept 19, 2007 16:53:07 GMT
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we own this thread. lmao
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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Nev
Part of things
Dugong fanclub member
Posts: 884
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Sept 19, 2007 16:56:08 GMT
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Calm Down Boys, Put the dyno reports away! Oh what the hell
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Maximum signature image height = 80 pixels
1967 Chevrolet El Camino
1984 Honda C50
1985 VW Polo 16v
1989 Ford Escort Popular Plus (Ex Hirst cabs)
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Sept 19, 2007 17:02:03 GMT
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500bhp LS1 engine weighs about 180kg fully dressed.
Pinto engine is about 140kgs i think, so add some more weight for all the turbo bits needed to make 500bhp YB and i think it might get a closer to the weight of the V8.
if you build for lightness then i guess the turbo smal engine will be lighter, but in the real world, using common engines, thereare option to fit big light weight V8's if you want them.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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starionturbo
Part of things
Is planning mental turbo action MU HUH HUH!!!
Posts: 528
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Sept 19, 2007 17:10:12 GMT
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But the original post is comparing 2 engines with the same BHP... A 1.6 turbo engine will be a smaller block than a 2.4 ltr so as far as weight difference goes it'll be minimal. It one of those arguments that will rage on forever. As mentioned before to get the best out of any given car it comes down to so much more than BHP/Torque, driver ability and how "used" to the car they are, Track cars take into account suspension set up, tires etc and the same with Drag cars. The type of turbo, charger you fit will have an effect on the engines powerband it's all very complicated BUT as i said A forced induced car will produce more torque than an N/A car of the same horse power. for example: my 1988 starion 2.0ltr EX when new in stock form (12psi) BHP=177@6000rpm Torque=214lbs/ft@3500rpm Taken from Mitsubishi Brochure. Now modified (14.5psi) BHP=212.8@5317rpm Torque=216lbs/ft@4924rpm Taken from Rolling road print out. 2007 Civic type R BHP=198@7800 Torque=142@6000rpm Taken from HERE Both engines are 1998cc, the starion is 8v as opposed to 16v and doesn't have vetec, it does however have a small turbo bolted to it
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Sept 19, 2007 17:13:22 GMT
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But the original post is comparing 2 engines with the same BHP... A 1.6 turbo engine will be a smaller block than a 2.4 ltr so as far as weight difference goes it'll be minimal. 1.6 pinto and a bored out 2.4 pinto would weigh the same I reckon, untill you add the turbo bits to the 1.6. yeah it could rage on forever, as it was on turbosport, untill the circuit racers came on with lap times andshut us all up. your comparing 2 litre engines, i was talking about big n/a engine versus small turbo engines, thats where the difference is.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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