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Is The Lexus IS-F Worth the Sum Of Its Parts?

Now that the media blitz about the IS-F is over, it is time to sort the facts from the fiction. How good is the IS-F? Or better yet is it worth more than the sum of its parts?

 

First of all I want to say the IS-F is a credible entry in to the up scale Uber-Sedan market. Luxurious, quick, and by most accounts a pretty competent all around performer. Simply put, the IS-F is unlike any Lexus ever produced. But is it a real value?

 

We do know how it stacks up against the fellow Uber- Sedans and to be quite honest it fares pretty well, in most categories the margin of error between drivers can tip the scales either way. But how does this stack up to something like a standard IS350? Using the averages of the new IS-F from Motor Trend, Car and Driver and Edmunds tests on both models we get the following table:

 

 

2008

2007

 

 

 

IS-F

IS350

Delta

 

0-60

4.57

5.3

-.73

secs

1/4 mile

12.97

13.9

-.93

secs

Weight (lbs)

3805

3517

288

lbs

 

 

 

 

 

60-0

106

122

-16

feet

Cornering

0.91

0.83

0.08

g-force

 

 

With a 0-60 average of just over 4.5 seconds and a ¼ mile time of 12.97 seconds the IS-F seemed to have proved its merits on the drag strip. The standard Brembo brakes also seem to be very impressive shortening 60-0 stopping distances about 15 feet over compared to its IS 350 sibling. Even the cornering g’s have been upped by .08. The only downside is that the big V8 and 8 speed transmission tag on an additional 288lbs to the package. Now if there is an Achilles Heel for the IS-F it seems to be the added weight.

 

So by buying the IS-F we see significant improvements on most fronts, but at what price? A well equipped IS350 will hover at about $40,000 and the IS-F will set you back at least $60,000 if no premiums are attached. This leaves us with a pretty hefty difference of at least $20,000.

 

So if you want the performance you must pay the price, because you really don’t have a choice? Maybe not.

 

If you stroll over to our good friends at Club Lexus and read the IS forums, you will definitely will see there are alternatives. Actually with amazingly few modifications a garden variety IS 350 can actually beat the IS-F in the ¼ mile. To add insult to injury, if you follow the link provided, you will find to do that it will take under $1200 of parts and set of rear tires to break into the high 12 second range matching the IS-F!





 

Impossible you say?

Proof is in seeing so to speak. For about $1200 in parts and a good wrench, the average guy on the street in an IS350 can now seriously play with the big boys. Actually just plop down a set of sticky tires on all four corners and that .08g in lateral acceleration advantage the IS-F holds is history, also half of that 16 ft stopping power is probably gone as well. The rest is easily solved with better brake pads. But now that isn’t apples to apples, now is it? So if you really want to match the IS-F in overall braking, you can shell out an additional $2500 and an afternoon and bolt on your own Brembo 14 inch brakes as well. Of course you probably want a better suspension too, so toss in $250 for a set Eibach springs. Keep the struts the same though because they are they differ only with a bit heavier damping to compensate for the IS-F’s additional weight.

 

So what exactly would it take to match the IS-F with using an IS-F 350?

 

I thought you would never ask. It seems more than one individual has matched the IS-F by installing only a cold air intake, catback exhaust, and two rear tires. But we want to match the IS-F over all not just in a straight line, so to do so we would need the following:

 

Cold Air Intake

200.00

Cat Back Exhaust

1000.00

Tires

1000.00

Springs

250.00

Brembo Brakes

2500.00

 

$4,950.00

Labor

$2,300.00

 

$7,250.00

 

 

While you can try this exercise with a lot of different cars, the cost of modifications typically exceed the cost of the faster model to begin with, making the factory offering the better deal. However the good folks over a CL showed me that this is not necessarily the case with the IS-F. Best of all the modifications will take nothing away from a standard IS350.

 

By the way if you aren’t handy with the tools the estimated cost of having a good wrench perform these upgrades will typically tag on $2300 to the deal. Making the worst case savings of at least $12,500 over the IS-F. But that leaves us with plenty of budget for fancy seats.

 

Club Lexus Thread

 

Google Spreadsheet link

 

 

So is the IS-F really that good? Or is the IS350 just an exceptionally better deal?

 

 

 

 

 


Is The Lexus IS-F Worth the Sum Of Its Parts?



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theoptimisticpessimisttheoptimisticpessimist - 11/28/2007 2:32:28 PM
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Flame War in 1 2 3 .....

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adamsaf723adamsaf723 - 12/1/2007 11:10:31 AM
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In any case, is the M3 worth the price difference between it and the 335i?


LexusKindaGuy12LexusKindaGuy12 - 11/28/2007 2:38:16 PM
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im sure there are more things in that ISF than those 5 categories.

anyways, you pay for the exclusiveness. and to play devils advocate, do you really think an IS350 is worth 35K base if you take it apart?


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Agent009Agent009 - 11/28/2007 2:55:27 PMView My AgentSpace
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The key performance differences are:

Outsourced:
Brembo Brakes
Specific springs and struts
Custom Trim and seats

Swiped from other models:
V8 (w/t custom cams)
Transmission from LS Series (no changes)




Agent009Agent009 - 11/28/2007 4:46:52 PMView My AgentSpace
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Ah HoustonCutie you are right those "Kustom" body panels make a big performance advantage.




RealitySmackRealitySmack - 11/28/2007 4:51:41 PM
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Exactly! The point I was trying to make about spending $7k or whatever to obtain same performance/feel!


w209w114w209w114 - 11/28/2007 5:09:59 PMView My AgentSpace
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HOUSTONCUTIE

We have definitely made som progress with you. At least we no longer get the dreaded "ALL CAPS RESPONSE".

"What about the highly Bolstered leather-trimmed sport seats with distinctive "F" styling?"

Answer: a Atitched "F" on a seat with extra padding?

"What about the Blue LED indicator needles which are surrounded by machined aluminum rings?"

Answer: Most cars use LEDs to power their gauges, and some have fancier chrome.

What about the uniqure aluminized compsoite trim that is use on the console and the doors?

Answer: MY FAVORITE ONE! "uniqure aluminized compsoite trim" another way of saying spray painted metallic plastic

What about the sculpted fenders?

Answer: Tack on body kit?

What about the the 19-inch BBS wheels that are bulit to Lexus perfection and specifications?

Answer: BBS is nothing special

What about the Sport Mode on the Lexus IF Vehicle Dynamics Integrated Management System (VDIM)?

Answer: My little brother's Lexus has that, its called overdrive.

You definitely romanticized and fantasize about these cars in every way imaginable.



RealitySmackRealitySmack - 11/28/2007 5:22:41 PM
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Although, other things that the other poster mentioned can all be added for maybe $1-2k. But, lets say you ignore all those...

-------
What about the Sport Mode on the Lexus IF Vehicle Dynamics Integrated Management System (VDIM)?

Answer: My little brother's Lexus has that, its called overdrive.
-------
Now this feature alone with 3 different modes is pretty good and I bet you won't be able to find it in after-market for cheap!

Next item would be the first 8speed direct sport shift transmission. That's another item that will bump up your price tag. And for most car lover's, the transmission is crucial! The IS350's paddle shifters aren't great and are not designed to shift as the IS-F's do. Oh, and don't forget about the engine tuning to achieve that growl with an extra intake...

So, you're still far away from the performance/feel even with after-market products. So, might as well just dump the money on a brand new car then spend it on after-markets that won't get you even close.



M35MTM35MT - 11/28/2007 6:31:09 PMView My AgentSpace
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Houston that was the best comment you've ever made on this site. Nearly all your points were valid.


HyundaiHyundai - 11/28/2007 9:10:01 PM
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"What about the Sport Mode on the Lexus IF Vehicle Dynamics Integrated Management System (VDIM)?

Answer: My little brother's Lexus has that, its called overdrive."

You are saying that traction control is overdrive?

Wow. You learn something new everyday.. not!



KillBotKillBot - 11/28/2007 2:49:23 PM
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I'm not a fan of Lexus, BUT this seems to be a good car. I think that it's a little unfair to compare it to the IS350. When instead it should be compared to other cars in it's class. NOW, with that in mind, how does it fair against an RS4, M3, and Merc's new C63, in performance vs price.

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Agent009Agent009 - 11/28/2007 3:00:25 PMView My AgentSpace
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I tended to agree unitl I started looking and found it is not cost effective to say modify a A4 to match a RS4. Similar to BMW. The factory offered the better deal.

Plus when you buy those vehicle you get a high tech 8,000 RPM engine. Not a mildly modified Garden variety V8. The IS-F gets the majority of its horsepower from displacement not high tech.

Just release the restriction on the standard V6 in the IS350 and you darn near match the big V8 in performance. The horsepower is not the same but the loss of 300 lbs makes up for it.

Very basic low tech hot rodding.



BremboBrembo - 11/28/2007 3:36:06 PM
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I don't get what high tech has to do with cost effective performance. IS-F v8 does not rev high because the engineers wants the peak power to reach faster.

Some drivers like to rev up engine others like the power immediate.

Buyer should of this class of performance should ask "Would rather wait to 8000 rpm for peak hp or 6000?"

I assume the faster you reach peak torque and hp the faster you accelerate.



RealitySmackRealitySmack - 11/28/2007 3:37:35 PM
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^^^ I think the approach was different to make a high end sports sedan for BMW and Lexus! BMW chose to go with a lower displacement & high RPM engine with low Torque to achieve 414HP, while Lexus chose to go with a bigger displacement to achieve 417HP and much higher Torque. I don't see how that is low tech? They're just different approaches to achieve what you want...POWER! If anything, the 5L will have a better chance of showing it's true potential in after-market industry, while the 4.2L may already be at max.

Since BMW chose to make their engine lighter, they chose a smaller one and because of that if they didn't make it rev higher then the HP would be a lot lower. So, to compensate for that and compete in the market they're revving it in the 8k to achieve 400+hp.

So, I don't think one engine is superior to another ONLY because it revs differently. Both approaches are unique in achieving their target goal...Power to match the competition.



BremboBrembo - 11/28/2007 4:04:50 PM
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Reality: Exactly!


Agent009Agent009 - 11/28/2007 4:45:00 PMView My AgentSpace
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The Lexus V8 doesn't rev as high because the bottom end is apparently is stock. Probably because Lexus officials were against the car from the beginning. Show string budgets from clandestine operations make more compromises.

Evidently there appeared to enough gain with better breathing. Investing into higher revs took a back seat.

I guess you could go ahead and rev to 8K and watch the rods fly through the bottom.



RealitySmackRealitySmack - 11/28/2007 4:58:45 PM
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I am not entirely sure what you're trying to say but, making bigger displacement engine is no back door!

You HAVE to make a bigger crankshaft because there is GREATER Torque being applied to the crankshaft and more twisting moments on the parts. Therefore, I would argue that revving it higher is a back door solution because you end up with lower torque so you don't need to modify most of the parts to handle greater loads, other than high speed motion, which would be less violent on the parts than that from a greater torque! With bigger displacement engine, you need tougher parts due to the amount of force being generated on the crankshaft through the ConRods. And that's definitely not LOW tech and a back door solution.



gsh23gsh23 - 11/28/2007 2:56:04 PM
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we dont even know the official price! no comparison can be made yet.

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stash84stash84 - 11/28/2007 5:33:41 PM
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i put a down payment (blk/blk isf) and the salesman told me that it would be around 65k..and they only come fully loaded..thats what i was told


w209w114w209w114 - 11/28/2007 2:57:20 PMView My AgentSpace
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Wow Great ARTICLE! A nice little Expose of the this car.

BTW. They forgot to mention, its $7,250. for the average joe but Toyota with its economy of scale can get it for at least half the price.


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HyundaiHyundai - 11/28/2007 9:14:47 PM
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How about that overdrive traction control, huh? What a scam..


RealitySmackRealitySmack - 11/28/2007 3:02:32 PM
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Yea, I agree on the fact that this car is in NO WAY in the same class as an IS350. With the logic of buying more after-market parts to make it on par doesn't mean anything. Because with that logic you can buy an STI or an EVO or maybe a GTO that can own the road. So, it's just not a good comparison.

You can say the same about a 335i or an A4... So, why attack on IS-F/IS350 but, not the others? I'm not pulling for one or the other but, logically it doesn't makes sense to do these kind of comparisons and start flame wars... IMO.


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M35MTM35MT - 11/28/2007 3:11:43 PMView My AgentSpace
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I agree.

009, several BMW fans (maybe even you) have mentioned they'd rather get the 335 versus the M3, because you get nearly as good as performance at a lower cost...explain?

You pay for the package...its as simple as this. Most Nav systems are 2,000 as an added factory option. A top of line Nav from Best Buy is $500, at most? Same difference.



w209w114w209w114 - 11/28/2007 3:15:12 PMView My AgentSpace
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You missed the point of the article. This was about paying $20K more (factory) for the extra performance versus $7k (aftermarket). It wasnt intended to downclass the IS-F


RealitySmackRealitySmack - 11/28/2007 3:20:09 PM
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Another thing I forgot to mention is that by getting an IS350 over an IS-F and modifying it to meet your needs (whatever they may be) will have a negative effect on the warranty.

So, the question is, are you willing to spend same as an IS-F and have a risk of violating the warranty and most likely it WON'T still have similar feel/performance to higher grade model? That being said, I'll take the IS-F, if I was in the market with enough money to spend! Same goes for M3 over 335i, etc, etc...



Agent009Agent009 - 11/28/2007 3:30:37 PMView My AgentSpace
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You need to read the laws on the warranty.

For example if you mod an engine the engine warranty is "potentially" void. But the brakes are unaffected. In this case they would be hard pressed say an air filter could damage an engine. Remember these are simple mods and easily reversed, so don't make a mountain out of a mole hill.

You can thank our good friends over at SEMA for having such legislation passed.



RealitySmackRealitySmack - 11/28/2007 3:45:17 PM
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I understand what you're saying but, the IS-F along with the M3 and RS4 all have been tuned greatly from the factory from their lower counterparts. And the performance/feel one would get from that kind of set-up would not be matched by spending $7-8k, in my opinion.


M35MTM35MT - 11/28/2007 4:00:16 PMView My AgentSpace
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No, I did not miss the point of the article, you missed my point.

009 wants to know if its worth the sum of its parts. Well, with ANY car, you pay more for the high end version than if you were to mimick the performance yourself.

You pay a premium to get it from the factory. People who buy these cars dont mod them. Modifications (for the most part) are for those who want performance at a lower cost.

For the gains mentioned, a 15-20k premium makes sense. There's also the intagible money factor (the "F" badge"). It's like that guy who mod's a 3 series and puts an "M" badge on it...it's still not an "M" car.



RealitySmackRealitySmack - 11/28/2007 4:08:20 PM
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Yes, I understand what you're saying. And I also understand that no high end sport sedan in these segment costs that much, if you take away the badge. But, what I'm saying is that with mods that are worth $7k, you will not get the similar performance/feel. And again there's that warranty issue. I'm sure everyone knows about the Vishnu chip on the 335i. And with that mod, it is more on par with the M3 than an IS350 would be with the IS-F.


S4cabriofoxoneS4cabriofoxone - 11/29/2007 12:03:03 AMView My AgentSpace
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M35, I have come to the conclusion that I would buy an M3 over a 335i any day of the week. Period. But I can see why somebody would want to save a bit of cash and tune a 335i... which is $50K with a few options anyway. So why not stretch a little more? The only real excuse evident is that you need xDrive so you can only have a 335xi.


AdmiralT20AdmiralT20 - 11/28/2007 3:03:19 PM
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Great article.

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KillBotKillBot - 11/28/2007 3:08:07 PM
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Is the 5 liter V-8 a Toyota built motor?

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montyz81montyz81 - 11/28/2007 3:08:42 PM
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for 67k, i'll take a GTR thank you!

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autoproautopro - 11/28/2007 4:21:33 PMView My AgentSpace
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Yea buy the nissan when you drive it off the lot your 67 grand will become 40 grand,real smart!


stash84stash84 - 11/28/2007 5:36:21 PM
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very true


M35MTM35MT - 11/29/2007 8:40:13 AMView My AgentSpace
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autopro,

you mean like the way a 2006 S-class can be bought for 45-50k right now? When it was 90k new? hmmm what the hell is your point?!



kpaxxkpaxx - 11/28/2007 3:08:52 PM
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All these are indicators of track performance..how does each of these cars perform on the track that is the question?

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gsh23gsh23 - 11/28/2007 3:14:02 PM
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to give toyota credit, isnt the 5.0 V8 made by yamaha? or at least, the ISF V8 has yamaha made parts (cam shafts, hollowed out titanium valve stems, other stuff i dont know about...)?

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Agent009Agent009 - 11/28/2007 3:34:08 PMView My AgentSpace
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I may be incorrect but I thought Toyota leaned on Yamaha for the cams timing and valve train.


r15mohdr15mohd - 11/28/2007 3:54:13 PM
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i wouldnt say crush...the IS350 and IS-F are in line with its competitors

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StarStar - 11/28/2007 7:09:54 PM
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...you mean both are mediocre cars that fail when compared with the superior German cars.

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caymandiver75caymandiver75 - 11/28/2007 3:54:00 PM
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I'd just like to say that total mods on the IS350 12 second runs added up to less than $1500. $500 on spare set of OEM rear wheels and R tires, $650 exhaust, $90 intake tube, $220 on Eibach springs. The part that was priceless is the -1800 DA weather conditions for the 12 second run. Had an IS-F run at the same time it too would have benefited. Clever article and I'm sure you got the best flame suite on that you could find.

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M35MTM35MT - 11/28/2007 4:04:06 PMView My AgentSpace
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"Clever article and I'm sure you got the best flame suite on that you could find."

"L"augh "M"y "A"** "O"ff



Agent009Agent009 - 11/28/2007 4:40:49 PMView My AgentSpace
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Well I wasn't expecting the actual owner to jump right in there!

But the more the merrier!

BTW - I have the best flame suit money can buy...LOL



Agent009Agent009 - 11/28/2007 4:50:28 PMView My AgentSpace
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caymandiver75- I realize you can run the quarter mile faster for less. as you have so aptly proven.

But the IS-F is an all around performer and I felt it was justified to add the additional cost to make a stab at beating the IS-F on all fronts for less.




autoproautopro - 11/28/2007 4:19:41 PMView My AgentSpace
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The engine in previous M3's has been known to crap out.Unskilled may have helped this happen,but happen none the less.

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EL34EL34 - 11/28/2007 4:30:07 PM
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Here we go.

Another walk around the block!


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stash84stash84 - 11/28/2007 6:22:03 PM
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This article is great for me. I currently own the is350 (daily driver) and i just ordered the 08 isf a couple months ago. I plan to leave my 350 stock but I plan to add a couple of modifications to my isf. Im ONLY considering the ones that are covered under warranty (exhaust/intake) and maybe suspension. I understand (009)that non-oem mods wont affect the warranty (remove them before going to the dealer) but id prefer to get the mods directly from Lexus and have them install them. For the 350, there are not many mods that are offered by Lexus. There are many available for the upcoming isf (Lexus Website). I know the point of this article is to compare a stock isf to a modified is350 and see if the isf is worth the extra 20k. Honestly, bang for your buck, is350. I actually like the exterior better and the ventilated seats (not offered in the isf, from what ive heard) but there is no replacement for displacement. With the 5.0 isf engine and a few thousand dollars, i think that the power is unreachable for the is350.

Also, when we compare the v8 audi, the m3 and the c63, why doesnt anyone ever compare torque?? Doesnt horsepower really directly affect 0-60 time? Isnt torque considered available power at any given time?? If so, wouldnt the isf be the 2cd fastest in its class behind the c63? It has 371 ft lbs of torque over 295 for the m3 and 317 for the audi. I know we need to consider weight but the isf has alot more torque than the bmw and audi....


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S4cabriofoxoneS4cabriofoxone - 11/28/2007 11:58:38 PMView My AgentSpace
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Sure, but that doesn't necessarily make it quicker off the line. The M3 weighs less, and the RS4 has AWD--both give them advantages in straight-line speed. They can both match or beat the IS-F from 0-60.


stash84stash84 - 11/30/2007 1:58:24 PM
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right..they are very close in 0-60 times but what I was asking was if the extra ft lbs of torque that the isf supposedly has (also, taking into account the weight difference), would make it quicker than the audi v8 and m3..obviously, while the cars are already moving. there is a very lengthy explanation that realitysmack and kaiser have been posting and i dont fully understand it yet but im sure with time i will get a better idea on which car is faster. (not 0-60) just faster (30-80mph) (60-120mph) etc...(most of the time, cars are already moving)


RealitySmackRealitySmack - 11/28/2007 7:25:53 PM
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It's all about the gear ratios my friend ALL about the gear ratios!

HP comes into play at higher speeds but, initially Torque is where it's at. Remember a measurable quantity in any engine's output is Torque not HP. A dyno only measures torque and calculates HP from it using RPM as well. Since, HP = (TQ*RPM)/5252.


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RealitySmackRealitySmack - 11/28/2007 7:29:32 PM
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This is why I was making my point earlier about 5L vs. 4.2L and the importance of revving it higher and lower with respect to displacement of an engine. Lower RPM does not mean "Low Tech"!


RealitySmackRealitySmack - 11/29/2007 10:43:42 AM
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First, let me start of by saying that if you believe I espouse notions about torque and power, well, I don't. I am stating what I say from my experience and having learned from engineering in school and also after working at an automotive company. So, the way I like to think of TQ/HP is by understanding that TQ is a *Rotational* equivalent of force, which has the potential to do useful work. And HP is the RATE at which work is done.

With the definitions in mind, some of your points from your lengthy explanation are valid and I don't disagree with all of them, however, there is more and I mean A LOT MORE to figuring out how a car performs at the wheels then just take 2 numbers (TQ/HP) from the manufacturer and go base everything from that. You need to look at all the data on your output curves. As I always say that 0-60 (acceleration) is not as simple as one would think, given you've examined the governing equations.

Since, you are a student of the physical science, I thought it would be good to have a discussion on what makes a car accelerate and to back-up my earlier point about gear ratios (Transmissions) and torque! Keep in mind that the tractive Force that makes (pushes on the ground) your tires move is:

F_e = ((Engine TQ)*(Total Gear Ratio)*(thermal Eff))/(tire radius) .......(1)
Vel = Road Speed = (Ang. Vel)*radius ........(2)

Now, this equation is simplifid to not take into account losses from aerodynamics/rolling friction but, I have stated this way to simply it and convey the point! You can see that acceleration is dependend on torque. As I said earlier, torque/gear ratios are important for accelerating. This is EXACTLY why transmissions were invented! And that's why lower gears tend to provide more torque at the wheels then higher. And you need higher gears because you can't spin the lower gears fast enough to compensate for increase in power. That's why lower gears tend to spin at a faster rate and provide more power even though they produce low torque.

The equation above is interesting because in the end it is the Force at wheel that pushes you forward. Again, you can see the variables. P.S: Notice the subscript "e" is for engine. We were looking at the TQ/HP of the engine but, since you mentioned tires, I thought I would discuss a bit about that too. The road speed is solely dependent on TQ and RPM (the wheel RPM). Therefore, Dyno's only measure TQ because TQ is a *Rotational* equivalent to Force. And dynos only measure the "resistance" produced by that *Rotational* force and calculate HP from the rotation speed. So, again, HP is important but, TQ is what the Dynos measure.

What affects top speed? 3 reasons: Aerodynamic drag, losses through the transmission, and tire friction. The loss from each of these sources increases as engine speeds up. But, you will reach a point where all the engine's power will be used to overcome these losses and almost none is left over for acceleration. That's why the TQ/HP curves don't



RealitySmackRealitySmack - 11/29/2007 10:55:33 AM
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"...That's why lower gears tend to spin at a faster rate and provide more power even though they produce low torque..."

Sorry for the typo! What I meant to say was lower gears produce more torque and spin less because of higher ratio number.



RealitySmackRealitySmack - 11/29/2007 11:00:18 AM
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Didn't realize there was a limit to how much you could post in 1 shot. Some of my additional text was cut off and I have included here to conclude my point...

"That's why the TQ/HP curves don't.....infinitely increase with speed! Now, after a talk on the theory, there's also a practical side to all this as well. This is evident when you compare NASCAR/F1 cars to say ... an average economy car. F1 engines tend to rev up to 15000-20000 rpm and why do they spin this fast? Because they want to keep the car lightweight and achieve more power with SMALL displacement engines! Because of this set-up, those race engines do NOT last long due to higher engine speeds, which fatigues the material life VERY quickly. On the other hand, you look at an economy car and it revs much lower but produces more torque to maintain HP. And they last a LOT longer too! Maybe in the near future, when we have better valve-trains that can keep up with these speeds we will see engines that can go up to tens-thousands of RPMs.

So, the bottom line is, a high revving engine is not necessarily BETTER than a low revving engine! And low revving engine are not "Low Tech" because you need to compensate for the additional TQ (Rotational Force) acting on all your parts."



RealitySmackRealitySmack - 11/29/2007 4:59:46 PM
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Okay, you seem to be confused about what I'm trying to say about Dynos. So, I'll explain in the simplest terms that I am capable of.

A Dyno is a type of machine that is used to measure TQ and speed (RPM) from which HP produced by an engine can be *calculated*. Yes, a Dyno provides graphs for both TQ and HP but, it uses the Rotational Force (TQ) and RPM from an engine to equate the Power along small variations in speed. It is much simpler to do this because TQ and RPM is what power is (Rate of doing work)! And that is to say, HP depends on both of them. There are a wide variety of Dynos but, the simplest ones have a coupler system that measures the resisting rotational force (a.k.a TQ) and it also has a sensor to measure the speed at any given load (rotational resisting force). So, my point was that from this information, the Dynos are able to figure out the energy/power produced by the engine, NOT measure it!

And my statement about Dynos measuring TQ still holds true. Because Dynos could either be transmission Dynos or absorption Dynos, or some other. But, the former utilizes devices that measure TQ, in terms of the elastic *Twist* of the shaft. And the TQ is produced by the load that the engine is carrying. Unlike transmission Dynos, absorption Dynos produce the TQ that they measure by creating a constant restraint to the turning of a shaft, by applying mechanical friction or electromagnetic induction or any other type of *Force* resisting friction. So ANY type of Dyno only *measures* or creates a *force resisting friction* to measure TQ and speed and then *equate* HP from the two!

The simplest form of Power is:
Power = (Work/time) = F*Vel

And from that you can get the equation that you have stated by simplifying it to get Accel. I won't list it again since, we know what we're talking about. But, here's a question: what other types of Forces are included in that equation? If you ponder on that for awhile, you will see that you'll get what I have listed in my previous post. For simplicity, I left out Aero/Rolling/Rotational Inertia/Static forces, which are important as well. So, even if it seems complex, it cannot be ignored. The equation you stated works fine as long as you know the true power at every instance but, what I was talking about was from a little deeper theoretical point of view. And where I was getting at was the fundamental question of: where does power/energy come from in any given IC engine? The answer to that is from the pressures of the burning gases that transmit forces down through the ConRods to the throw of the crank and to the crankshaft. You have TQ when force is acting at given distance from the fulcrum. So, then you can see how TQ is obtained and secondly HP from TQ and RPM.

I am not disagreeing on the fact that Power is some arbitrary unit pulled out of a hat and TQ isn't. They BOTH are quantifiable but, it is far simpler to imagine TQ because that can be viewed as rotational force and can be translat



RealitySmackRealitySmack - 11/29/2007 5:03:25 PM
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continuation of above....

"....force and can be translated into Force which, ultimately moves the vehicle forward.

The equation you stated is simpler ONLY when you have the true values of power at every instance and that is exactly what Dynos *Equate*. But, if you didn't have Dynos and you were trying to figure out Accel, then that equation would be of no use and would have to be expanded. And in the end you would get something similar to what I have along with all those terms omitted for simplicity.

In the end, all I'm saying is that to determine Accel it is much simpler to use TQ, instead of HP, and it's even more simpler to use the tractive Force at the wheels because HP/TQ are dependents of Force (the fundamental quantity in it's simplest form)! "



BremboBrembo - 11/29/2007 8:10:21 PM
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Excuse me for interrupting, I've been reading your post (both people) and I have to say that this is very interesting. I wish I could have appreciate physic more when I was in college.

No sarcasm.



RealitySmackRealitySmack - 11/30/2007 10:24:33 AM
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Again, as I said earlier, you seem to be missing the point, whether or not you want to accept that or not is your choice. But, don't make a foolish argument by saying that Dynos don't equate HP. If you had a slight understanding of how they work you would know that a Dyno is a type of machine that measures loads. Think of it as a load cell which, measures the amount of Force being applied to it by measuring the changing resistances. In the case of Dynos, the transducers convert any applied force into a usable torque signal which it then supplies it to a gauge or a data acquisition program (i.e. LABVIEW, you'd know what it is if you've ever worked with it