The infamous ultimate supercar thread.

[Tornado]

Was the FD RX-7?

 

[Jay]

Yep.

 

[Stevisiov]

The square law for aerodynamic drag is good, but not good enough. 384hp might get you sor in a perfrect world. But, then you have turbulence, extra drag from lift/downforce effects... so my 400-450 is probably closer to the mark.

I think a certain members sig is applicable here. In theory, theory and practice are the same. In practice, they are not.

 

[mafia_boy]

R32 wasn't sequential Viper?? I thought it was sequential.

The FD was sequential, that was for sure. And the EJ20TT from a couple of years later was sequential too, but I'd always thought the R32's were sequential, not simultaneous like the Mk3 Supra.

Ohwell.

 

[mPWRD]

Nope. R32 runs simultaneous twin turbos. One off the front three, one off the back 3.
A quick google search brought this up... Link

But the FD was... as are the new BMW TT engines... but there seems to be a lot more power in those Bimmer 3.0's than the 300 that they make... is BMW holding back a skosh to save the M3's bacon? Or is 300 hp really all that they can do...

Oh, and I think I'll just deal with the supercar thing on my own now. This thread is now just for talking technical. Hence the name change.

 

[Tornado]

but there seems to be a lot more power in those Bimmer 3.0's than the 300 that they make... is BMW holding back a skosh to save the M3's bacon? Or is 300 hp really all that they can do...

Ignoring the versions of the engine "officially" tuned for more power (740i), there was a huge aftermarket explosion for the 3-series when the N54B30 first came out. Not only is it supposedly massively underrated from the factory, but the 335Ci is apparently something akin to the IROC-Z of BMWs when it comes to cheap power gains. Its safe to say that 300 HP isn't something hard for it to accomplish.

 

[mPWRD]

I'm just surprised that they got 300-hp with 2 turbos... so is the N54 just an N53 with a pair of turbos bolted on? Or is it a completely different block...

 

[Tornado]

I'm just surprised that they got 300-hp with 2 turbos...

How come? What would you expect?

so is the N54 just an N53 with a pair of turbos bolted on? Or is it a completely different block...

Completely different block. ///M-Spec can probably correct me, but I'm of the assumption that the N53 is simply a direct injection version of the N52, and the N54 is actually a highly modified version of the old M54. What I do know for sure is that the N52/N53 and N54 are completely unrelated engines.

 

[mPWRD]

OK. Just clarifying. That would explain the different power outputs. I think the N53 is a newer block than the N54.

 

[niky]

BMW's power ratings are all mostly for marketing purposes, to enable better separation of their model range by power outputs... but there's a good reason for conservative power tuning from an engine longevity (and drivetrain longevity) standpoint.

Besides... it's good psychological marketing tactics to have a 300 horsepower car feel like it has more by tuning more for midrange torque than going for top-end power.

 

[Jay]

R32 wasn't sequential Viper?? I thought it was sequential.

The FD was sequential, that was for sure. And the EJ20TT from a couple of years later was sequential too, but I'd always thought the R32's were sequential, not simultaneous like the Mk3 Supra.

Ohwell.

Nope twin equal sized and rated turbos running off seperate 3 port manifolds, R33 and R34 are the same, this is the reason you often see big twins rather than the usual huge single you see on Supras (also because they're on the passenger side, left side and no steering and brake master in the way). This is also why the turbos are so easily swapped on stock manifolds (N1 turbos, twin 2530's etc), rather than the Toyota way of squeezing it into one big bundle.

They did this so they could have good overall flow and package them tighter to the engine (eg more knuckle grazing...), the engine was developed with racing in mind rather than the drivability of sequentials (which they dont lack either)

 

[mPWRD]

Nope twin equal sized and rated turbos running off seperate 3 port manifolds, R33 and R34 are the same, this is the reason you often see big twins rather than the usual huge single you see on Supras (also because they're on the passenger side, left side and no steering and brake master in the way). This is also why the turbos are so easily swapped on stock manifolds (N1 turbos, twin 2530's etc), rather than the Toyota way of squeezing it into one big bundle.

Yeah, I've read reports about a modified R32's propensity for INSANE turbo lag... floor it... wait... wait... wait.... and then the turbos kick in and you're gone. Have you heard anything about the stock version's turbo lag (if there is any)?

 

[Jay]

Well who ever is driving like that is driving it wrong.

Any small engine with huge turbos arn't going to respond at low end, weather that be a GTR, Evo, Supra, STi or anything.

Heard anything about stock lag? No I have driven them, a stock GTR usually provides good boost over 3000rpm and a rev limit of 8000rpm which is a 5000rpm worth of great torque, extra efficient turbos from HKS and others can provide similar or better powerband with more boost.

but heres the thing, I have.. and do drive many turbocharged small engines (under 3 litres) and large NA engines, things like lag might seem a problem for someone out of a large engined car as they used to driving to suit that type of engine, once you get seat time in high powered smaller engined turbo cars you realise low end response (under 2500rpm) is not a issue as you have changed your driving style to suit a rev revving boost happy engine.

If you release the clutch just off of idle then flatten the throttle you are not going to get much the response that a small NA engine would, but if you want to shoot off like a rocketship then slip the clutch a little to keep the revs around 2500-3000 and the torque is all there, once the turbochargers boost is max set the torque is very flat (due to boost regulating of the wastegate), the GTR has a 4500-5000rpm torque band stock which means it is quite linear in accleration and gearchange response is very good.
The bigger turbos and the larger the intercoolers and piping the less inital response you will get, keep in mind the GTR has a 900-1000 rpm idle which means you don't need all that much extra revs to start producing usable boost.

 

[the Interceptor]

There's a very specific reason the x35i came out the way it is. I wrote this some time ago in another thread:

I read an article the other day about that twin turbo engine. The goal BMW wanted to archieve (and I suppose they did) by bolting on a pair of turbos was not to boost up the engine. Instead, they wanted to use their positive effect on efficiency and driveability. See this as an improved NA engine, not as a turbo-lagged "kick in the back"-machine. Hang on, I'll just get that article to put in some quotes ... *goes to the bathroom*

EDIT: Alright, here we go. These are parts of an interview with the leading engine developer from BMW, Klaus Borgmann, taken from the german car mag "AutoBild Sportscars":

Borgmann:"The primary goal in development was to combine the efficiency of a six cylinder with the dynamics of a V8. We wanted the specs of a medium sized V8, combined with the fuel consumption and - most importantly - the smoothness of our six cylinder." [specs of the new six cylinder: 306 hp and 295 lb-ft]
(...)
As a major goal were spontaneous reactions, a single turbo seemed to be too unattractive. Its reactions on accelerator movements would have been too indolent, and the characteristics too edgy at full throttle. So, the guys from Munich decided to use two turbos, each one powered by three cylinders. The advantages were much more spontaneously reactions of the smaller turbines due to smaller [and therefor lighter] rotating masses. This way, even small accelerator movements create reasonable propulsion, as little amounts of exhaust gases are enough to make the turbos spin.
(...)
To reduce the timespan between pushing the accelerator and the reaction of the turbos even more, the engineers used another trick. Using the direct fuel injection, the turbos are being kept spinning with large valve timing overlap [I don't know the exact words in english, what I mean is when the in- and outlet valves are both open for a short period of time to create a specific effect like this one] and an air stream of unused intake air. So, even when you're cruising, the turbines are being kept spinning with some pressure.
Well sized overpressure valves are another trick to improve fuel economy. As long as you don't access power, the exhaust gases are being disposed past the turbines. The advantage: the turbos do not raise the counterpressure, the engine has an easier time pushing the exhaust gases out and uses less energy. Only when you push the accelerator, the valves close and you get the boost you need immediately.
Another part of the story when it comes to efficiency is the use of high-strength steel for the turbos. Only a few years ago, the turbos needed to be cooled with fuel, which decreased the fuel economy. Turbos made of the new steel can resist the temperatures up to 1000 °C almost without any cooling.
(...)
Borgmann:"Even when driving progressively, this engine uses less fuel than the 3.0 NA engine [this one is based on]. Due to the higher torque, you unconsciously use higher gears all the time." That reduces fuel consumption so much that it even compensates casual power runs. Put into figures, the new six cylinder uses 2 litres less on 100 km [equals a jump from 20 to 24 mpg] than the BMW 4.0 V8. Additionally, this engine weighs 70 kg less than the V8, making the car more agile.

Regards
the Interceptor

 

[nk4e]

Well who ever is driving like that is driving it wrong.

Any small engine with huge turbos arn't going to respond at low end, weather that be a GTR, Evo, Supra, STi or anything.

Heard anything about stock lag? No I have driven them, a stock GTR usually provides good boost over 3000rpm and a rev limit of 8000rpm which is a 5000rpm worth of great torque, extra efficient turbos from HKS and others can provide similar or better powerband with more boost.

but heres the thing, I have.. and do drive many turbocharged small engines (under 3 litres) and large NA engines, things like lag might seem a problem for someone out of a large engined car as they used to driving to suit that type of engine, once you get seat time in high powered smaller engined turbo cars you realise low end response (under 2500rpm) is not a issue as you have changed your driving style to suit a rev revving boost happy engine.

If you release the clutch just off of idle then flatten the throttle you are not going to get much the response that a small NA engine would, but if you want to shoot off like a rocketship then slip the clutch a little to keep the revs around 2500-3000 and the torque is all there, once the turbochargers boost is max set the torque is very flat (due to boost regulating of the wastegate), the GTR has a 4500-5000rpm torque band stock which means it is quite linear in accleration and gearchange response is very good.
The bigger turbos and the larger the intercoolers and piping the less inital response you will get, keep in mind the GTR has a 900-1000 rpm idle which means you don't need all that much extra revs to start producing usable boost.

unlike this?

 

[mPWRD]

@interceptor: thanks... nice article. And that clears it up. Because they could have gotten a lot more power out of the 3.0 if they wanted to... and there's still room for improvement. which will be good because then they have to spend less on developing a whole new engine.

 

[Jay]

unlike this?

What about it?

 

[mPWRD]

If you look at the second video (once the first one is finished), the guy belches black smoke out of the exhaust. So obviously, something went wrong. That's just my two bits, probably not what nk4e was going for...

 

[nk4e]

Well, I probably misunderstood about Viper's post. Though it seem that driver builds up boost but he was over revving it in the Supra. I tried to show physical evidence of what Viper was talking about. How the a turbo needs to idle at a higher point to get that boost. But then again, I am going to search for the question.

 

[Jay]

If you look at the second video (once the first one is finished), the guy belches black smoke out of the exhaust. So obviously, something went wrong. That's just my two bits, probably not what nk4e was going for...

Nothing went wrong, black smoke is fuel, thats how they keep the cylinder temps down to prevent detonation without retarding too much timing (major power killer), smaller engines and more boost, more likely you are going to see black smoke.

Infact that second video has less black smoke then I expected.

BTW I mean during high throttle and loads, not during normal driving and cruising it, then it would nice and near stoich (near perfect air/fuel burn ratio)

Well, I probably misunderstood about Viper's post. Though it seem that driver builds up boost but he was over revving it in the Supra. I tried to show physical evidence of what Viper was talking about. How the a turbo needs to idle at a higher point to get that boost.

Yeah in that case he's just showing off for the camera.

 

[theewar]

I advise you to read this:

http://www.pilgrim.demon.co.uk/alex/atheists.htm

That was a very good read mPWRD..
And good luck with your super car

 

[mPWRD]

You may have forgotten about me, but I'm back.

I was the idiot who thought that he could design and build an 800hp, 200mph car from scratch based on what he had read in a magazine. No experience to speak of, just a kid with a dream. And then that kid had to answer some questions. Which he didn't know the answer to. So that kid did what any kid confronted by an uncomfortable truth would do.

I lied. I fabricated a web of lies that only served to destroy any semblance of ethos I had. I took someone else's work and tried to pass it off as my own. And naturally, I got torn apart for it. By the time I realized I was in over my head, I had spent weeks furiously digging myself into a massive hole. I put together a feeble attempt at an apology, only to get it lobbed right back in my face. And finally, in a coup de grace, I attempted to change the subject.

Believe it or not, this moment of Internet idiocy always stayed in the back of my mind. For something that had no consequence on my actual life, it provided both a painful memory and the motivation to never again approach a situation without being armed with the requisite knowledge.

So, you may be (but probably aren't) wondering, did he do it? Did he build his ultimate supercar?

No. (John Hennessey did.)

But here's what I did instead.

I got my degree in mechanical engineering. I did four years of Formula SAE. I got a job at a major OEM. I currently work in (ironically) tire development, and now realize that tires are the single. most. important. part of the car. I bought a GTI. I stopped playing driving games and started learning how to really drive. I've taken up autocrossing and I'm building up a Saturn SL2 into a Lemons car with some friends of mine.

Essentially, I grew the *censored* up.

Part of growing up is knowing your limitations. Formula SAE gave me an appreciation of the sheer amount of time, effort, money and know-how it takes to build a vehicle. And that was a 300-lb., steel-tube-frame racecar that didn't have to pass FMVSS or NHTSA tests. The dream is still there, though. I may end up influencing the development of a supercar, using the knowledge and resources of my employer. I may end up branching out on my own and attempting to build a car of my own. But I may never build my ultimate supercar, and that's a truth that I can live with.

Growing up also means owning up to your mistakes. I re-read this thread after coming across a similar case on a different forum. I realize now how naive I was. So here, now, five and a half years too late,

I'm sorry.