engine placement hight argument
03-09-04, 12:23 PM
#1
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engine placement hight argument
my friend and I have a little argument. I say the drop of a v8 in to the fd would hurt the handling because the engine owuld sit higher, he thinks it wont sit high enought o makea difference.
so who is right, will it hurt the handling (provided its an aluminum block so it would weigh the same asa 13b), and if yes then how much?
has anyone here converted and can tellf rom experience, and lets not be bios now guys I love the rotarya dn would not go any other way but I want the truth.
thanks!!
so who is right, will it hurt the handling (provided its an aluminum block so it would weigh the same asa 13b), and if yes then how much?
has anyone here converted and can tellf rom experience, and lets not be bios now guys I love the rotarya dn would not go any other way but I want the truth.
thanks!!
03-09-04, 01:04 PM
#2
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Even an iron block will weigh about the same as the stock engine. The 13B itself is not as light as you'd imagine, plus you have the weight of the turbos, the intercooler, and plumbing.
The V8 will have a lower CG. Most of the inside of a V8 is air, most of the real mass is down low, since the crank centerline is at the bottom of the engine instead of up in the middle like in a rotary. Likewise, the total CG is lower because the *transmission* is several inches lower as well.
But in the end, YES the V8 will "affect" the handling, in the sense that you have a complete crapload of torque available at practically any RPM, instead of the stock engines half-crapload available "sometimes".
The V8 will have a lower CG. Most of the inside of a V8 is air, most of the real mass is down low, since the crank centerline is at the bottom of the engine instead of up in the middle like in a rotary. Likewise, the total CG is lower because the *transmission* is several inches lower as well.
But in the end, YES the V8 will "affect" the handling, in the sense that you have a complete crapload of torque available at practically any RPM, instead of the stock engines half-crapload available "sometimes".
03-09-04, 01:10 PM
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does that go for the v8s only or would that be the same for the inline 6's and such, crank centerline is low and such, tranny senario should be the same. Anyway, but when you get down to it the handling is different but not worce. What I mean was does the car corner just as well (as long as you do it right)?
03-10-04, 07:54 PM
#4
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What do you mean by cornering?
If you mean grip, grip has only to do with the weight of the vehicle and the quality of the tires. You will do much worse to grip by installing crappy tires than you could with an engine swap.
If you mean handling... see my first response above.
Also bear in mind, static weight distribution and static center of gravity don't mean that much when it comes to actual *handling*, unless something is severely out of whack like, say, a Corvair or 911. The static loads just serve to tell you what kind of suspension tuning the car would like. I've driven cars with probably 65/35 weight ratio where you could barely keep the tail behind the front, and I've driven cars (I drive one daily, actually) where it's more like 52/48 but it plows mercilessly unless you get stupid with the throttle... which again points out that the power available and the way that power is delivered are an important part of the handling equation.
Inline 6's would tend to not be as good weight-distribution wise because they tend to be taller, yet weigh about the same as your typical V8.
Also bear in mind that pushrod V engines are very space efficient and they keep most of their mass low to the ground, what with their relatively light cylinder heads and the benefits of keeping most of the valvetrain deep inside the otherwise wasted V. That's why Chevy has dedicated themselves to pushrod engines, and Chrysler is moving back to them, while Ford is stuck with a bunch of overweight, huge-for-the-displacement suhc motors...
If you mean grip, grip has only to do with the weight of the vehicle and the quality of the tires. You will do much worse to grip by installing crappy tires than you could with an engine swap.
If you mean handling... see my first response above.
Also bear in mind, static weight distribution and static center of gravity don't mean that much when it comes to actual *handling*, unless something is severely out of whack like, say, a Corvair or 911. The static loads just serve to tell you what kind of suspension tuning the car would like. I've driven cars with probably 65/35 weight ratio where you could barely keep the tail behind the front, and I've driven cars (I drive one daily, actually) where it's more like 52/48 but it plows mercilessly unless you get stupid with the throttle... which again points out that the power available and the way that power is delivered are an important part of the handling equation.
Inline 6's would tend to not be as good weight-distribution wise because they tend to be taller, yet weigh about the same as your typical V8.
Also bear in mind that pushrod V engines are very space efficient and they keep most of their mass low to the ground, what with their relatively light cylinder heads and the benefits of keeping most of the valvetrain deep inside the otherwise wasted V. That's why Chevy has dedicated themselves to pushrod engines, and Chrysler is moving back to them, while Ford is stuck with a bunch of overweight, huge-for-the-displacement suhc motors...
03-10-04, 08:55 PM
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Originally posted by peejay
Even an iron block will weigh about the same as the stock engine. The 13B itself is not as light as you'd imagine, plus you have the weight of the turbos, the intercooler, and plumbing.
The V8 will have a lower CG. Most of the inside of a V8 is air, most of the real mass is down low, since the crank centerline is at the bottom of the engine instead of up in the middle like in a rotary. Likewise, the total CG is lower because the *transmission* is several inches lower as well.
But in the end, YES the V8 will "affect" the handling, in the sense that you have a complete crapload of torque available at practically any RPM, instead of the stock engines half-crapload available "sometimes".
Even an iron block will weigh about the same as the stock engine. The 13B itself is not as light as you'd imagine, plus you have the weight of the turbos, the intercooler, and plumbing.
The V8 will have a lower CG. Most of the inside of a V8 is air, most of the real mass is down low, since the crank centerline is at the bottom of the engine instead of up in the middle like in a rotary. Likewise, the total CG is lower because the *transmission* is several inches lower as well.
But in the end, YES the V8 will "affect" the handling, in the sense that you have a complete crapload of torque available at practically any RPM, instead of the stock engines half-crapload available "sometimes".
cast iron chevy V8 - ~550 lbs
What about the intake, alternator, etc, you say? Well V8's need those too!
V8 has a lower CG? Only if you mount it upside down. As for the tranny, are you speaking from experience or merely speculating?
Sounds like you've been reading upo at Granny's speed shop - where they weight of a rotary is exagerated to include the air conditioning, power steering, and weight of the driver.
03-10-04, 09:22 PM
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by handling I meant the weight. Take the viper for example, put it in to the turn to fast the the nose will swing right around like an anvil on a chain and spinning you will go. So good weight distribution is pretty essential to good handling.
good point about the inline sixes sitting high.
also here is what one member mentioned, but he had worked on suspention on the rotary powered one so...
"Going from a STOCK 13b to an LS1 T56 with the battery moved to the luggage comp, the difference is very small, but if you are comparing a stripped 13b (with downpipe air pump removed rats nest removed, single turbo small battery, then things will be different. It changes the feel of the car. I have a 93 touring with an LS1 T56 and a procharger on it, as well as a 93 R1 CYM with many weight saving mods on it that weighs around 2600. The LS1 car comes in at around higher 2800# nubbers and has stock suspension on it, and the CYM has springs and Tokikos on it. There is no doubt that the CYM handles better, but the LS1 is much better to drive. These arent comparing apples to apples , but it is a starting point. The LS1 car I had driven for about 5 months prior to the swap, and it was all stock down to the cats."
also what about V6's? they have their weight low like the v8's. Would a v6 powered fd handle better then a rotary powered one? Would a v6 fd handle better then a v8 powered one?
good point about the inline sixes sitting high.
also here is what one member mentioned, but he had worked on suspention on the rotary powered one so...
"Going from a STOCK 13b to an LS1 T56 with the battery moved to the luggage comp, the difference is very small, but if you are comparing a stripped 13b (with downpipe air pump removed rats nest removed, single turbo small battery, then things will be different. It changes the feel of the car. I have a 93 touring with an LS1 T56 and a procharger on it, as well as a 93 R1 CYM with many weight saving mods on it that weighs around 2600. The LS1 car comes in at around higher 2800# nubbers and has stock suspension on it, and the CYM has springs and Tokikos on it. There is no doubt that the CYM handles better, but the LS1 is much better to drive. These arent comparing apples to apples , but it is a starting point. The LS1 car I had driven for about 5 months prior to the swap, and it was all stock down to the cats."
also what about V6's? they have their weight low like the v8's. Would a v6 powered fd handle better then a rotary powered one? Would a v6 fd handle better then a v8 powered one?
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03-11-04, 08:17 AM
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I'm not going to say to much about it but come on. Have you ever seen a V8 out of a car next to a rotary? HUGE difference. and most of the weight of a V8 is up top, not the same with a rotary. No difference?!?!? Oh and about the handling. The RX7 was years ahead of its V8 compeditors. .98g lat G's. with 50/50 weight distribution back in 93. Ford or Chevy didn't catch up to that till 8 years later. Ok yes. They did have cars that could go faster in a straight line but you could not go fast and then turn without hitting a tree.
03-11-04, 12:29 PM
#9
Old [Sch|F]ool
Originally posted by rxAustin
The best way to lower the CG of a V6/V8:
- leave the cylinder heads off
- mount the block upside down
The best way to lower the CG of a V6/V8:
- leave the cylinder heads off
- mount the block upside down
03-11-04, 01:47 PM
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Originally posted by peejay
That won't work... most of the weight in the shortblock is down at the bottom where the rotating assembly is.
That won't work... most of the weight in the shortblock is down at the bottom where the rotating assembly is.
Stay off the drugs, boy. (Hint - the block ain't light)
03-11-04, 03:43 PM
#11
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No, the block isn't light, but MOST of the weight in the SHORTBLOCK is down at the bottom.
Say you have a 135lb block. The cylinders are maybe .150"-.200" wall thickness 4" by 5" tubes, the deck is maybe .200-.250" thick, the sides are maybe .150" or .100" or so. But the main webs are hugely thick, the main caps are beefy, and those ar down at the bottom of the block.
Now you also have a crank that weighs maybe 55lb, a 30 pound flywheel, the rods weigh maybe 2 pounds each (times 8) with much of that mass down at the bottom. The pistons are higher up but they're maybe a half pound each.
I stand by my assertion.
Say you have a 135lb block. The cylinders are maybe .150"-.200" wall thickness 4" by 5" tubes, the deck is maybe .200-.250" thick, the sides are maybe .150" or .100" or so. But the main webs are hugely thick, the main caps are beefy, and those ar down at the bottom of the block.
Now you also have a crank that weighs maybe 55lb, a 30 pound flywheel, the rods weigh maybe 2 pounds each (times 8) with much of that mass down at the bottom. The pistons are higher up but they're maybe a half pound each.
I stand by my assertion.
03-11-04, 04:56 PM
#13
Old [Sch|F]ool
Haven't forgotten it. 
But some wag said to leave the cylinder heads off, so I was rolling with it.
What about the transmission? That sits everal inches lower on a boinger. Or what about that big high-speed flywheel sitting several inches lower?
It all balances out to be just a bit lower, maybe about even if you're using a small-block Crappy engine. But this all is looking at minor details on the bigger picture - a radically different torque curve.
But some wag said to leave the cylinder heads off, so I was rolling with it.What about the transmission? That sits everal inches lower on a boinger. Or what about that big high-speed flywheel sitting several inches lower?
It all balances out to be just a bit lower, maybe about even if you're using a small-block Crappy engine. But this all is looking at minor details on the bigger picture - a radically different torque curve.
03-11-04, 09:31 PM
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he is right, the block does get bigget towards the top but its aluminum, and the crank and piston rods, oil pan, and tranny is all down low, everything is except the heads but I am sure everything that is aoutweighs the difference no?
03-12-04, 01:21 PM
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Well, PJ - you forgot the oil pan. How low do you intend to mount that engine? You realize it won't go so well with the oil pan dragging the ground.
The CG of the crank is.... at the crank centerline. The rest of the engine weight sits above this. Therefore, the CG is above the crank centerline.
The crank centerline can't sit that low - that pesky oil pan again. It's alot taller than a rotary oil pan ya know.
BTW - speaking of "wags" (whatever that's supposed to mean) - you're the one who "intelligently" ported your exhaust so high your powerband comes on at 5500 RPM.
Go buy a clue somewhere.
The CG of the crank is.... at the crank centerline. The rest of the engine weight sits above this. Therefore, the CG is above the crank centerline.
The crank centerline can't sit that low - that pesky oil pan again. It's alot taller than a rotary oil pan ya know.
BTW - speaking of "wags" (whatever that's supposed to mean) - you're the one who "intelligently" ported your exhaust so high your powerband comes on at 5500 RPM.
Go buy a clue somewhere.
03-12-04, 02:30 PM
#16
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The crank can sit practically on the crossmember, whereas the rotary has the E-shaft mounted way up in the middle of the engine. Didn't you ever wonder why the trans tunnel in an RX-7 goes almost all the way up to the hoodline?
BTW - That was where torque peak seemed to be, which seems to be common for streetports (that late intake closing killing off dynamic compression at lower RPM). It still had some *serious* grunt down low thanks to the overlap. Never needed to shift out of 5th gear down to about 25mph.
BTW - That was where torque peak seemed to be, which seems to be common for streetports (that late intake closing killing off dynamic compression at lower RPM). It still had some *serious* grunt down low thanks to the overlap. Never needed to shift out of 5th gear down to about 25mph.
03-12-04, 03:03 PM
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You still forgot the oil pan. If you stick the crank of a V8 at the crossmember, the oil pan WILL stick way out below and very likely nail the ground.
I'm done with this topic.
I'm done with this topic.
03-18-04, 09:09 PM
#19
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Originally posted by rxAustin
You still forgot the oil pan. If you stick the crank of a V8 at the crossmember, the oil pan WILL stick way out below and very likely nail the ground.
I'm done with this topic.
You still forgot the oil pan. If you stick the crank of a V8 at the crossmember, the oil pan WILL stick way out below and very likely nail the ground.
I'm done with this topic.
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