Coupe vs Fastback

[DSC]

For racing, which one is better and why?

Looks like all of the factory nissan race cars were fastbacks.
But everybody who races in ITA (dono about s13's in its, have yet to see one) runs a coupe.

Tnord and I were talking about it and just had guesses but no real answers.
Coupe is stiffer/lighter stock vs stock compared to the fastback from everything i've heard.
But given minium weights and a roll cage, it seems like they would be equally stiff and light.
So, since the fastbacks are more aerodynamic, why isn't it the choice for club racers in the US?
Only answer I could come up with is maybe the s13 can't reach its minium weight?

For the factory racing, I guess they have gobs of power and aerodynamics is more important than 30lbs or however much?

If anybody knows or cares to join in on the guessing...

[Dousan_PG]

mm one advantage of a fastback is you can get a fiberglass hatch. that would drop a ton of weight....

cant help much otherwise

[KiDyNomiTe]

Originally posted by dousan36
mm one advantage of a fastback is you can get a fiberglass hatch. that would drop a ton of weight....

cant help much otherwise
I think nissan just has a thing for hatches, they used the Zs too, they were hatches, maybe there is some hidden fact about hatches.

But I also have heard about the coupe bieng stiffer and all.

[DSC]

Originally posted by dousan36
mm one advantage of a fastback is you can get a fiberglass hatch. that would drop a ton of weight....

cant help much otherwise

What class allows a fiberglass hatch though?

[tnord]

i think what he means is a lexan window to replace the glass. which he is right, would drop a significant amount of weight from the place it is most hamrful......up top.

[Dousan_PG]

ah yes that too
but you can get the whole hatch in fiberglass...

dotn know about what class it is in though, not too keen on that stuff, still learning

[240racer]

Isn't it possible to have a complete roll cage in those race cars? If so, then you just use that to get all the stiffness you need. The body is just a body, hatch or coupe. The hatch is more sporty, some might say and that's why they went with it. It is also probably more aerodynamic. Also, there aren't any s14 hatchbacks, so there's only going to be s14 coupe ITA cars. If I had a race car of that caliber, the body would be as few of peices of fiberglas as possible and the structure would just be tube frame. I don't know if that is legal in all those classes, but I'm sure you can get really close by bending rules and such.

[Bbandit]

fastback is faster
"fast"back ---> fast!
coupe ---> just coupe (ex: can a have a coupe of coffee please?)





bad joke :(

[2FortyessX]

Originally posted by Bbandit
fastback is faster
"fast"back ---> fast!
coupe ---> just coupe (ex: can a have a coupe of coffee please?)





bad joke :( agreed :)

[HippoSleek]

Rollcages under SCCA IT rules are only allowed a certain number of attachment points (8) and then only at particular locations. Most 240s that you will see racing today are running in ITA or ITS and follow this rule. The older factory cars and some other efforts existed in the GT2 and GT3 classes where tube frame cars were allowed. Absent a tube frame, there is no way make the hatch as rigid as the coupe.

Also, unlike GT cars, IT cars must use original body panels. Carbon fibre and fibreglass replacement panels are illegal (as are lexan windows). Thus, there is not way to overcome the weight of heavy glass in the hatch. Also, while weight rules may ultimately put both the hatch and the coupe at the same minimum weight, the weight in the hatch is located in a horrible position, relatively (high and at the back of the car).

There is no "bending the rules" in IT -- you will be protested, they will dismantle your car, and you will be disqualified. See, AARC runoffs where MANY top cars were DQ'ed after a visit to tech.

While the fastback might offer a few more mph on the straights, the added weight and weaker chassis make the coupe a better race car for club racing. Where rules are more open and money is no object, the fastback's aero-vantage would make it the winner.

See you next week - hopefully w/ pics of a new toy.

mark

[tnord]

and as usual when it comes to questions about classing and rules dealing witht he SCCA.......mark comes through with the answer.

you goin to pick up a miata mark?

[Zemus]

Well i hear that coupes the the best because of their lack of weight, but i could say the FB would be easyer to add a roll cage to because of its openness. And its much easyer to gut that whole 2lb if that from the hatch, and its easyer to take out the seats, if that even makes a diffrence :D

[91CRXsiR]

how much does the glass on the hatch weigh? i know my hatch is really heavy. my struts are bad so i have to use a stick to prop up my hatchlid..

are there any negatives to using a lexan windows?

how do they shatter? in shards or large chunks?
and how clear is it? and resistan to heat? or direct sunlight it would suck if it melted in the hot cali sun.

[adey]

Wouldn't the better weight distribution of the hatch give it a slight advantage as well?

Pros to hatch: better weight dist. and better aero.
Pros to coupe: lighter and more rigid rear end.

Am I missing anything? just how much more rigid is the coupe, and what difference would this make (if any) that wouldn't at least partially be negated by it's poorer weight distribution?

[AKADriver]

Any weight distribution disatvantage there may be is far easier to overcome than a floppy chassis if you're not allowed extensive bracing. A light and stiff 55/45 beats a heavier, higher cg, flexier 53/47 any day.

[A51PS13]

hey i dont know if this is tru i could care less but this dood i know at Stillen said my coupe was 50/50 with the sr20det. Im jus sayin cuz Stillen usually know there shizzel. Either which way.

Coupe Pros: Its Just Better
Hatchback Pros: There are none.

Haha no im jus messin. Maybe Im jus a lil biased haha.

[Dousan_PG]

Originally posted by A51PS13
Im jus sayin cuz Stillen usually know there shizzel.


you're joking right? LOL

[A51PS13]

well im jus sayin man phil at stillen seemed to know his shizzel when i met him at Area 51. so yeah . Does ne one say hes wrong in that the s13 w/sr20 isnt 5050.

But beyond that coupes r better.haha

N dont hate man i jus dont know shiz about my car man. I only got into nissans in june. I was a Honda man before dood.

[Dousan_PG]

stillen knows so much they sell 2 left Z32tt calipers at there garage sales!!!

sells a full set of brake lines for a 240sx yet its too long and all for the rears

i paid 20 bucks for the lines
i didnt get the calipers (already had them)
overcharge on prices for their products.

dont trust stillen! its stealin! they f'd my friends car too when they worked on it!

and Area51, arent they going out of business?
i went there once, um...rip off!

and the SR isnt much lighter then the KA. its a MYTH


i aint hating on you, just dont believe businesses who are in it for $$$$ rather then helping people.

[ruf]

Originally posted by DSC
Looks like all of the factory nissan race cars were fastbacks.What gave you this idea? I don't think I've EVER seen a factory 180SX race car.

As for the Stillen, I know a mechanic that used to wrench on the Stillen 300Z IMSA team. The only reason they used the Stillen bodywork was that some weird loophole in the rules allowed them a weight break if they ran it. No one really liked it much. I personally hate Stillen. I buy all my AP stuff direct. I won't even give them the pleasure of putting a dumb Stillen sticker on my calipers.

[A51PS13]

Well. I dont buy from Stillen. I buy from Phil. N dood Stillens good for some things man. Find somebody else that can tell me the color of the tach wire off the ECU for the G35(we were installing an AFC ) not even the freakin techs at the dealership knew. Oh and we have the wiring diagram also. it dont say. As for Area 51 man yeah My boi shut down the shop cuz he wanted to get out of it. Too bad u got ripped off though, i got hooked up. But cmon if ur not cool with somebody in the industry ur gonna get ripped off thats just how it is

[DamnedButDetermined]

Originally posted by dousan36
i aint hating on you, just dont believe businesses who are in it for $$$$ rather then helping people.


Sorry to point this out, but EVERY BUSINESS is in it for $$$$!

Learned that one in collage:D

[Dousan_PG]

Originally posted by DamnedButDetermined
Sorry to point this out, but EVERY BUSINESS is in it for $$$$!

Learned that one in collage:D

learned that but not how to spell

college

not every business is ONLY for money
some do it to help people as well. at least the businesses i associate myself with. then again, i get such great prices, must be just me!

[Dousan_PG]

Originally posted by A51PS13
My boi shut down the shop cuz he wanted to get out of it. Too bad u got ripped off though, i got hooked up. But cmon if ur not cool with somebody in the industry ur gonna get ripped off thats just how it is

nah i NEVER went at area51 for buying stuff.

just walking in their show room i was like 'i gotta get the **** outta here'
hahah

btw, i havent ever paid retail for any product on my 240sx. except gas and tires. everything else was dealer cost or below. or free. sponsors are cool.

[AKADriver]

Originally posted by ruf
What gave you this idea? I don't think I've EVER seen a factory 180SX race car.

All the 240SX IMSA cars were fastbacks.

But, those were tube framed cars.

[adey]

Originally posted by dousan36
i havent ever paid retail for any product on my 240sx. except gas and tires. As a drifter, I think those are precisely the two things that you'd save the most money on paying below "market" price. :) I think you need a tire sponsor. Gas, well, that's a tough one unless you can convince 76 that you're worth their gas!! :D

[wherezmytofu]

its a simple fact that the coupe has a cool rating of 8.9 some people quote it as a full 9.2, i ran it thry the coolno machine and got a 8.96 but i hadnt wash the car in a while, anyhow the fastback is only rated as 7.8, max i've seen stock is 8.3 and that was pushing it

[DamnedButDetermined]

Originally posted by dousan36
learned that but not how to spell

college

not every business is ONLY for money
some do it to help people as well. at least the businesses i associate myself with. then again, i get such great prices, must be just me!

I was kidding about the collage thing, and there isn't a single SMART business owner out there that doesn't want to make money. There would be no point in offering your experience if you weren't making any money. Racing Car Owners are a totally different thing...they are crazy about racing so they are in it to loose money!

I was trying to be a smart ass:rolleyes:

[wherezmytofu]

Originally posted by DamnedButDetermined
I was kidding about the collage thing, and there isn't a single SMART business owner out there that doesn't want to make money. There would be no point in offering your experience if you weren't making any money. Racing Car Owners are a totally different thing...they are crazy about racing so they are in it to loose money!

I was trying to be a smart ass:rolleyes: i got that uber-fly college edgumiocation!

[DamnedButDetermined]

Originally posted by wherezmytofu
i got that uber-fly college edgumiocation!

maybe i didn't go to college long enough, b/c i can't tell if you are aking fun of me or sidding with me? hehehehehehe:D

[wherezmytofu]

Originally posted by DamnedButDetermined
maybe i didn't go to college long enough, b/c i can't tell if you are aking fun of me or sidding with me? hehehehehehe:D does it matter? :D

[DamnedButDetermined]

not really;)

I already got my point across!

[silvia240]

dood, no body opens a business to loose money.

[octane103]

........as opposed to tight money??:D

[KEINsm]

There's a reason why Nismo only used the S13 coupe for racing, rather than the RPS13.
Even with the S12 Gazelle, Nismo based their race cars off the couple and not the hatchback.
Of course in racing, you need to have room for the rear spoiler but it may also be for the better rear chassis reinforcement (like people have already mentioned).
I don't think it makes a whole lot of difference in Auto-X or weekend track runs though.



Originally posted by ruf
What gave you this idea? I don't think I've EVER seen a factory 180SX race car.

As for the Stillen, I know a mechanic that used to wrench on the Stillen 300Z IMSA team. The only reason they used the Stillen bodywork was that some weird loophole in the rules allowed them a weight break if they ran it. No one really liked it much. I personally hate Stillen. I buy all my AP stuff direct. I won't even give them the pleasure of putting a dumb Stillen sticker on my calipers.

[AKADriver]

Actually, some of the S12 race cars were fastbacks. The 200SX V6 rally cars were all fastbacks.

http://www.geocities.co.jp/MotorCity/9185/rally05.jpg
http://www.geocities.co.jp/MotorCity/9185/rally04.jpg

[AKADriver]

More S12 fastback fun!
http://www.geocities.co.jp/MotorCity/9185/FISCO.jpg
http://www.geocities.co.jp/MotorCity/9185/ssf3.jpg

[RedlineRacer]

Doesn't Kugochi only use fastbacks? I've never seen him in a coupe.

[nokeone]

i know this is slightly off topic (looks rather then performance) but just my personal preference is the Coupe with a Silvia front end conversion...to me that is the best looking combo...

as for performance...i guess it depends on what you want it for...

but i've seen both drift wonderfully...and i've seen both smoke other, should be better, cars at a track...

i think any difference is negligable..

[Dousan_PG]

Originally posted by RedlineRacer
Doesn't Kugochi only use fastbacks? I've never seen him in a coupe.

first
its Koguchi

second, he owns TOO MANY CARS
yes he has a coupe. kouki wing and blue. 400ish HP
how many cars you ask? let me count (i think he just got a old US Domestic i saw him drifting around it-SICK!!!!! )

this is probably old count from jan. 03 young version butyou'll get the jist..oh this is CURRENT too! not his entire life time w/ the S-chassis/various cars

DR30
GX71
DR30 (x2)
s13 (i dotn know what it says after aht..something different ig uess?)
BMW 30CS
A1755A (i've no idea what this is) (x3)
180sx (x6) = fastback
s13 (x2) = silvia
JZX81 (mark II)
JZZ30 (soarer)

he's da shi*t! and a very nice guy too! :)

[mrmephistopheles]

don't forget.. he's got
1337 x 11ty billion :)

[RedlineRacer]

Originally posted by dousan36
first
its Koguchi


Sorry Dousan, I forgot he is your hero. :) You got any pics of his coupes? I would like to see them. Does he have a website?

[Dousan_PG]

yeah he is. i've been a koguchi fan for a few years. the reason i got so interested in drifting 2.5 years ago :) hehe..

anyways..pics yes i have one or 2....of the blue coupe w/ GTR wheels (fronts are Advan Model 5s) and s14 kouki ks wing
sexy!
these pics were tire testing articles.
iirc, car made like 400hp or so..maybe 350?? i forget the turbine size too.


website? no. koguchi power has no website, it is small company. my friend is calling them (he better-i gave them his number) to try and get me some products so hopefully he'll do it! :) he's in japan right now.lucky guy!

http://www.imagestation.com/picture/sraid36/p4dca984ac317bf394fb8008836c3a7f5/fd21626e.jpg
http://www.imagestation.com/picture/sraid36/pdec8a7b070f4032d54dc1276caef4dce/fd21621c.jpg

[RedlineRacer]

OMG, I love his coupe. What kind of products is your friend getting?

EDIT: I love Advan Model 5's. I wish I had $2500 and I would get a set. Do you know of anyone who makes a good rim that resembles it?

[Dousan_PG]

i told him to call and get me the hood spoiler koguchi power makes and some other little things from various companies. he is lazy though so i dont have high hopes. but see what he can do with 240 dollars :p
japan IS NOT like usa. most thing need to be ordered so his friend might ship it back to me if needs be. no worries :)

[Dousan_PG]

Originally posted by RedlineRacer
EDIT: I love Advan Model 5's. I wish I had $2500 and I would get a set. Do you know of anyone who makes a good rim that resembles it?

there are a few
but i DONT support knockoffs and hate poeple who buy that junk. buy the real thing, they are stress tested as well as well built (forged maybe?)

anyways, knockoffs suck

[RedlineRacer]

Originally posted by dousan36
there are a few
but i DONT support knockoffs and hate poeple who buy that junk. buy the real thing, they are stress tested as well as well built (forged maybe?)

anyways, knockoffs suck

Yeah, I agree with you, thats why I said "do you know any good rims that resemble it", because I know you hate cheap knockoffs. But I am a cheap college student who loves 240's.

[nokeone]

Originally posted by RedlineRacer
Yeah, I agree with you, thats why I said "do you know any good rims that resemble it", because I know you hate cheap knockoffs. But I am a cheap college student who loves 240's.

yeah those are sweet wheels..

these are similar, of good quality, and less money:

5zigen Typhoone

http://www.5zigenusa.com/images/wheels/typhoon/typhoon_gunmeta.jpg

Advan Model 5

http://www.gruppe-s.com/Advan/adv_m5.jpg

obviously the Advans are way nicer...lol...but yeah..

[RedlineRacer]

Yeah, I use to like the typhoons. But I just don't like that deep dish look of them. I think I am just gonna settle on some 5zigen Fireballs.

[kpark129]

Originally posted by adey
Wouldn't the better weight distribution of the hatch give it a slight advantage as well?

Pros to hatch: better weight dist. and better aero.
Pros to coupe: lighter and more rigid rear end.

Am I missing anything? just how much more rigid is the coupe, and what difference would this make (if any) that wouldn't at least partially be negated by it's poorer weight distribution?

well here's a fact the s13 has better weight distribution compared to a 180sx in japan. but in the US the hatch as a slight advantage in weight distribution compared to the coupe but convert both of the hatch and the coupe into a 180sx and a s13 then the weight dist. goes to the s13.

[NekoPunch]

Isn't it possible to have a complete roll cage in those race cars? If so, then you just use that to get all the stiffness you need. The body is just a body, hatch or coupe.
Not all roll cages increase stiffness. Furthermore, you would have to weld the roll cage to the roof in order to counter all the flex you get from the hatch.

Absent a tube frame, there is no way make the hatch as rigid as the coupe.
Exactly.

Wouldn't the better weight distribution of the hatch give it a slight advantage as well?
But all you have to do is add more weight to the back of the coupe. Simple as that. You can add it at a lower point too in order to keep the center of gravity lower.

this dood i know at Stillen said my coupe was 50/50 with the sr20det. Im jus sayin cuz Stillen usually know there shizzel.
Umm, sure.... I weighed my 89 coupe w/ SR20DET and Silvia front end, full tank of gas, full interior, no driver, and the weight distro came out to 54/46. I could make it near 50/50 by throwing a couple hundred pounds in the trunk, but that would be idiotic.

and the SR isnt much lighter then the KA. its a MYTH
The weight difference is probably negligible comparing an SR20DET to a non-turbo KA, due to the weight of the turbo and whatnot. But various sources claim the SR short block is around 30-40lbs lighter than the KA.

yeah he is. i've been a koguchi fan for a few years. the reason i got so interested in drifting 2.5 years ago
If you get the '02 D1 Round 4 (Tsukuba) DVD, there's a cool bio on Koguchi with some footage of his first appearance on Vid Option many many years ago. He was probably in his early 20's and a monster even back then pulling some crazy entry speeds.

to try and get me some products so hopefully he'll do it!I'm heading over to Japan next week, so let me know what you're looking for and I'll try to pick it up 4u. Plus, I'm going to Fuji Speedway on 7/6 to watch D1 Round 4. Can you believe it? F'n FUJI SPEEDWAY!!! First D1GP ever held there.

well here's a fact the s13 has better weight distribution compared to a 180sx in japan.
Umm, no. Weight distribution is similar for Japanese and U.S. models.

I have both an 89 coupe and an 89 fastback. If you drive a fastback slowly over a small hill or do some quick maneuvers, you'll hear the hatch glass creaking and feel/hear the body flexing a LOT more than the coupe. But whether this makes a difference on the track is tough to say.

Two factors nobody has really mentioned. With the fastback you've got a lot more carrying capacity for tires, tools, etc. This is great for trips to the track. Also, nobody mentioned visibility. I like the visibility out of the coupe, but some might prefer the larger view out of the fastback glass and this can possibly help during an intense race.

[302INMY240]

the fastback does creak when you pull crooked in to a driveway, but with a foamfilled chassis, atleast a rear strutbar or a maybe even a 6-point rollbar with a cross brace, it wouldnt be any less stiff than a coupe with the same chassis mods.

i would definitely say, that the fastback has a lower coeficient of drag based on what i learned in my fluid mechanics course at school, but i do think that this would only make a big difference at very high speeds between the stock usdm variations, such as 160 and over.

i do think more of a difference would be noticed though between the fastback or 180sx, and the jdm silvia because of its more squarish front and back, and i think that could be proven to be a bigger difference.

ONE more consideration is that the tracks in japan are generally smaller and allow lower top speeds, meaning it doesnt matter, and you might notice the s15 is a fastback,
ok im done

[TBreu007]

I have an ITS S13 coupe I fully prepped myself. I know of at least one person here in the SE that has a ITA hatch. He can't make minimum weight, but still does well.
The main disadvantage of using the hatch is weight. The 80lbs or so more that they weigh is a huge penalty in racing. Since you can't replace any windows with Lexan or replace body panels with CF or fiberglass, you're pretty much stuck with a heavier car.
FWIW, with a nice custom SCCA legal cage, I could make a hatch as stiff as a coupe, but once again, the added weight of the tubing would probably negate the better aero of the hatch.
As far as weight distribution...with a car as close to 50/50 as the 240 is, changing spring rates can easily make the car as neutral as anything on the track.

[nokeone]

i'd like to see a show of hands of who on this board is actually using their cars to the fullest potential where all the factors mentioned would even make a noticable difference...

:aw:

[TBreu007]

:aw: Me

My post was answering DSC's initial post about which was best for racing and why. If DSC is building a true race car and was posting a question on it, I would hope he's prepping it to it's "fullest potential" otherwise what's the use.