awd vs MR..?

[pissonlotus]

ok this might be some stupid questions but i m gonna post it anyways..

awd vs mr drivetrain cars..
what's pros and cons for both cars..?
w/ same hp, sane curve weight, some skilled driver..

just wondering how the MR cars stand aganist awd cars...

thank you

[Jaicvc]

awd is more heavier... lol and driver for the mr should be me lol hehehhehe

[3sgtepower]

MidRear was classed with AWD classes in Japan's drag racing, because it offered similar grip advantage that AWD held. Its also lighter drivetrain weight, gets better fuel mileage.

[pissonlotus]

mrs' only con is small or no space...?
no hauling stuff and no car sex..?

oh.. and loud interior noise..?(my girl friend is already bitchin about that..)
niiice

[Dance_Business]

Originally Posted by pissonlotus

mrs' only con is small or no space...?

Not an issue for autocross & race stuff.

Originally Posted by pissonlotus

no car sex..?

That's why I'm married and own a home.

Originally Posted by pissonlotus

oh.. and loud interior noise..?

Again not an issue for race applications. Wear earplugs.

[1991turbomr2]

Originally Posted by pissonlotus

mrs' only con is small or no space...?
no hauling stuff and no car sex..?

oh.. and loud interior noise..?(my girl friend is already bitchin about that..)
niiice

MR2 = NO FAT CHICKS NO SEX BUT BLOW JOBS ARE ACCEPTED

[TomsMR2]

awd cars are a yawn fest to drive. properly setup, they're probably ultimately faster.

2wd rwd is just so so so so much more fun.

[shimric]

AWD is better for bank robberies. Seeing as that's what you're planning to do I'd go with that.

Good luck

[HarrisRacing]

Why doesn't anyone use the fact that the fastest cars in the world (F1 cars particularly) are MR??

Pretty hard point to argue.

But regarding the difference between my 04 Evolution and my 1991 MR2: Stock for stock the EVO is 90% of a racecar in factory trim, where the MR2 needed lots of work to keep up (granted there are decades between the two) the EVO really handles UNBELIEVABLY in stock form in autox or road racing.

BUT, The MR2 will be ultimately faster due to less weight, but I don't think AWD / RWD makes much a difference past 40 mph. You guys need to hit some big tracks.

Patrick

[kbrew8991]

but the weight distribution is the same no matter the speed

hidden advantage - braking with more weight towards the rear, under braking you have more weight on the rear even after weight transfer than those nose heavy pigs, thus we can ask our rear tires to help out more under braking

you must not have put much effort into your MR2, an AS Evo isn't nearly as much fun (got understeer?) as an ES MR2 (and I've driven both)

[mr2gq]

Have you ever did a donut in a AWD car? Well not really donut more like figure 8.Man that thing kicks ass!

[mr2nv]

This past season with my BEAMS 3sge, I regularly beat well driven Subaru STi's in autocross. Most of them had ultra high performance street tires compared to my r compounds. Now the EVO is a different story, at least where I live, being they are driven by nationally competitive drivers. I would love to see some of those AWD drivers try to drive a MR the same way. It seems like these new AWD cars have so much technology that they practically drive themselves.

Here's a good real world demonstration of how MR compares to AWD. This is the top 5 raw times of our last NY region SCCA event in October where it was pouring rain, huge puddles. Yun(mk1) was on v710's, Ken(mk2) was on Hoosiers and I was on v710's. The first STi might have been on r compounds and the 5th place STi was probably on streets.

1m CSP 6 Yun Ng MR2 50.698
2m ES 61 Ken Frey MR2 51.461
3m BSP 164 Todd Kean STi 51.505
4m SM2 13 Matt Klein MR2 51.724
5m STU 88 Dan Cheung STi 51.841

[kbrew8991]

local autocross results (unless you've got a bunch of nationally competitive guys that always bring 100%) are useless in an argument

you're welcome to compare PAX factors though, even if that is flawed its got a much more "accurate" sample

[hachi kid]

Originally Posted by HarrisRacing

Why doesn't anyone use the fact that the fastest cars in the world (F1 cars particularly) are MR??

Pretty hard point to argue.

But regarding the difference between my 04 Evolution and my 1991 MR2: Stock for stock the EVO is 90% of a racecar in factory trim, where the MR2 needed lots of work to keep up (granted there are decades between the two) the EVO really handles UNBELIEVABLY in stock form in autox or road racing.

BUT, The MR2 will be ultimately faster due to less weight, but I don't think AWD / RWD makes much a difference past 40 mph. You guys need to hit some big tracks.

Patrick

that's because AWD is banned in F1. I'm an F1 fan myself, and I DO prefer MR cars (much more fun to drive). but, AWD would ultimately be quicker. F1 teams would love to use AWD, but they can't cause the rules. they would also LOVE to use ridiculous groud-effects/sliding skirts, slick racing tires, turbos, active suspension, ABS, launch control, and any kind of engine they wanted, but they can't cause the rules won't allow them. like I said, AWD would most likely be quicker, but MR is MUCH more fun to drive, and I prefer MR over AWD anyway.




Joseph.

[HarrisRacing]

First of all, I haven't had the time to completely answer the question partially because it's too vague for a simple answer, and particularly because the question doesn't address the the major issue.

The major contributing variables include the following:
1) traction available at the surface
2) power available at the powered wheels

These variables are based on conditions which basically pit them against each other to present to the real question: Do I have enough grip out of the drive wheels to sustain the level of straight line acceleration grip of the surface wether it be 4 wheels or not? If you do, then the 2wd car is the better bet and I'll explain why...

To answer your question, lets use your assumptions: Cars have same weight (and distribution), same power at the motor, and same level of grip out of the tires. To meet this criteria would mean that the AWD car's chassis would need to be lighter to compensate for the weight of the additional drivetrain weight (2 extra diffs, driveshaft, and 2 extra axles). Which isn't fair or scientifically feasible, but OK you got it for my example.

If the MR car has enough grip out of the rear tires to sustain the level of grip for the power coming out of the corners, then the AW part of the equation is useless. In fact, it will be SLOWER because of the fact that the AWD car (by design) will have MORE rotational inertia of the driveline that the engine and brakes will need to overcome to make the car accelerate and decelerate. For example, in the MR car there are only rear axles and a rear diff. In the AWD car you get an extra driveshaft, axles, and 2 more diffs - this is unavoidable by the design. Even if you take into account that the AWD car would have a lighter chassis to have the SAME weight as the MR car, the rotational inertia would be the difference in performance. This is the same principle as putting lighter smaller wheels on a car and driving to realize the benefit of less weight spinning that you would need to start and stop around a track - Not to mention friction losses! As the final nail in the coffin, think if a really high power and high grip drag car. 4WD vs. 2WD. Then imagine how much power is being put down when the front wheels are being hung in the air...grip vs. traction available at drive wheels.

Now, this covers the straight line part of the equation (acceleration and braking) in that it all comes down to IF the MR car has the grip to equal the power to the drive wheels.

NOW lets talk about turning. Since the steady state of the car in a turn (Max G in cornering) rarely happens under power (really a car-specific thing), then the gain from the AWD is only on out of corner accelration (post-apex accel). The funny thing is, as you accelerate out of a turn the weight transfers more to the back tires, which ARE the drive tires of an MR which would normally result in MORE grip. Bad news for the AWD car is that as you accelerate out of the turn, the weight of the front gets lighter and the front DRIVE wheels of the AWD actually LOSE grip. Really this is TOO hard to judge or argue because it goes back to the original question: Does the MR car have the grip to equal the power to the drive wheels?? If true, the two cars will turn the same at steady state and the difference out of the turn would be a wash - especially because of the inertia differences in the frivetrain and weight transfer reducing grip in front of an AWD car.



Now for my credentials (for you guys who are knocking me). I race *something* almost every weeked. I've owned 21 cars. I'm 27 years old, a mechanical engineer and I build / work / race something EVERY WEEKEND if not everyday. I'm pretty dang good at both as well.

This is the 2nd MR2 turbo I've owned (NOT ES, but a BP car), but I use the EVO for autoxing and the MR2 for road racing (not quite finished yet) because of the price difference between the 2 (and the fact that I'm not going to chop up my EVO). If you haven't driven an AS EVO on R comps I suggest you do, It is an OUTSTANDING autox car - WAY faster than an STI. I autox EVERY event within 3 hours of me and have FTD'd in the car SEVERAL times. I actually out-paxed everyone a few times as well.

The MR2 is going to be my purpose-built racecar. Yes it will ultimately be lighter than an AWD and yes it will be faster because of that. There aren't any courses that get slower than 40 mph in my area so the AWD car isn't an advantage.

Need to see more?

Putfile - Welcome to my homepage! for lots of pictures and videos.

Thanks for the replies and input.
Patrick Harris

[mr2gq]

You say they lose grip on the front wheels when coming out a corner.Im no engineer but I dont think lossing grip to the front wheels isn't going to matter much. Most new cars with awd can sense which wheel has the most traction and will transfer the power to those wheels. Kindda like the ATB dif I got in my svt. We have fridaynight drags at the atlanta motor speedway and they put cars with about hte same amount of power and modes against each other, vettes mustangs evos ect. Doesn't matter the car. The eagle talon AWD cars annihilated everything! Built vettes and all. And I was watching the speed channel and they had a shoot out between the evos and sti's. All with the same amount of power and all avid race drivers and the STI's won. They also sai the evos have a problem when taking hard right tuns it will drop oil pressure and could blow the motor.

[HarrisRacing]

My comments:

1) Go to a real drag strip - Where real drag cars pull the tires off the ground. I built an 11.48 @ 121 mph 1994 eclipse GSX and would get killed by old tire-hangers running the same MPH in the 1/4. Your comment seems to be saying "I saw cars with similar tires and power running and the AWD's won". Which may well be the case for street tires, but slicks are a different story...the RWD car will make the most difference of the slicks.
2) EVO vs. STI is another whole debate - TOP GEAR did STI vs. EVO and the EVO destroyed the STI...interesting that the SPEED channel did the same thing. What kind of racing was it?
3) Losing grip on the front wheels doesn't matter much pulling out of a turn - thanks for agreeing with what I said. Therefore you don't need the FRONT WHEELS pulling if most of the weight is on the back tires (As long as you aren't making more power than the back tires can put grip on, which in that case the AWD "magic" would be putting all the power to the back tires anyway).
4) Watch my videos, lots of hard right hand turns - no blown motor and I ran 20 minute sessions all day (Until I finally killed the stock tires) going both directions on the track.

Thanks for the comments.

Patrick

[mr2gq]

Notice i said it trans. the power to the wheels with the most grip. So if your going in/out a turn it could be a back wheel that break loose. Which if you have awd its going to come into play and be able to come out the corner better, cause you got power going to all 4 wheels, than if you was in a rwd car and it just breaks loose and you spin out or w/e. And at the drag strip I was talking about they do have a tec inspection. So its not liek they're putting stock vettes against buil talons. And yeah you got a evo that takes hard turns. Whats ur point? These evo's was basically completely torn apart and everything gone over. Something you said you didnt want to do to ur's right? So I think they're taking corners just a little bit harder than urs. Just maybe ya think? Oh yeah and since going into corners all the power is on hte back wheels maybe someone should tell the dirty rally cars they should take the awd off

[HarrisRacing]

It should be apparent to others that I have proven my point pretty well, so I'm sorry that you don't think so. I am so glad you know better and I do so I guess I'll see you at the track one day in your AWD to prove me wrong. I qualified my statements with the traction of the surface (dirt and snow are excluded from my explaination) so you can table that comment because it's a different whole argument and since this isn't a RALLY forum we'll keep it like that.

Another simple fact is if you are RACING a car and the rules allow RACING TIRES it's pretty stupid not to invest in the most important part of any car to maximize it's performance (AWD or MR). In my experience (as well as Ferrari's, Lamborghini's, Lotus's, Porsche's, Maserati's, and Ultima's) MR is the way to go for circuit racing...sorry to inform you, but there aren't any RULES excluding street cars not having all-wheel-drive and these manufacturers still run a MR platform. ALSO the fastest drag cars in the world, and fastest circuit cars in the world run MR setup as well. So if you don't believe MY engineering and car-building experience, you might want to look at thier examples.

It is also apparent that you did not look at my site, nor do you know about the cars I've owned and built. Good luck with whatever you are driving.

Patrick

[kbrew8991]

Originally Posted by mr2gq

Oh yeah and since going into corners all the power is on hte back wheels maybe someone should tell the dirty rally cars they should take the awd off

who here races on gravel, mud, or snow?

there are a few areas where AWD is damn near required, a road course and drag strip isn't one of them