Unrealistic Turbo Characteristics

[CSLACR]

I think @Johnnypenso nailed it when he said the amount of cars is always the reason/excuse dished out, and it's kinda tired.
As I mentioned earlier, GT2 had decent turbo lag. 700+ cars on a PS1.

I'm positive it wasn't that complex then. Yet far better than currently in GT6.

 

[pete2783]

if you see it right the gauge pass the 0 i can't find a better video but i know what is possible get pressure in neutral
Another video, can't recognize the car but is what i want to show

That is some kind of Skoda with a diesel engine. Forced induction characteristics in petrol and diesel engines are significantly different.

It can be a little bit complicated to explain but the intake on a diesel is unrestricted and the output is determined by the amount of fuel injected... one of the inherent reasons why diesels are more efficient than petrol engines. So yes, you are more likely to see boost at low load in a diesel... also virtually no vacuum at idle... you can also see this in your video!

To the OP; Yes, I agree completely with your observations. I have been working on a realistic engine simulation model for some time now and the more I research the more hideously complicated it gets! Maybe one day I'll get it finished and have something to show... and maybe send to PD... that would be my dream!

 

[Mike_grpA]

@pete2783 Absolutely, I should've realised it must've been diesel. The engine sound threw me, as I forgot how refined modern diesels sound. Yeah diesels don't produce the vacuum petrol motors do because of the lack of intake butterflies, because as you said, they don't use them to regulate engine output. I also love how the only limit to the boost in a diesel is how strong you've built the internals and the block. A friend of mine has a cheap, modern 4x4 turbo diesel, and it runs over 30psi standard lol.

 

[pete2783]

@pete2783 Absolutely, I should've realised it must've been diesel. The engine sound threw me, as I forgot how refined modern diesels sound. Yeah diesels don't produce the vacuum petrol motors do because of the lack of intake butterflies, because as you said, they don't use them to regulate engine output. I also love how the only limit to the boost in a diesel is how strong you've built the internals and the block. A friend of mine has a cheap, modern 4x4 turbo diesel, and it runs over 30psi standard lol.

30psi and a massive diesel compression ratio, no doubt!... when you actually think about the forces involved that are acting on the pistons/crank... they're crazy!

 

[rixtar]

If it was a modern rally car that is too funny for words, since they all have very sophisticated anti-lag systems. I only have group b rally cars, and none of those have lag.

Also, there's a difference between a car dropping out of it's power band, and turbo lag. They feel very very different to one another, and a car of any aspiration will bog down if the revs drop out of it's power band.

The best way I can explain it is to compare two cars I've owned: An '87 corolla twin cam, and my current celica grp a.

The corolla had a 4age engine, which was an extremely peaky little engine. It red lined at 7,500rpm, and made no usable power below 3,500rpm. It only got into it's power band over 4,200rpm. Once over that magic number, it went like stink, and felt so lively. Under 4k it had very little to give. The throttle response at low revs was still good, although it mostly produced a louder noise, and didn't give the impression of power at low revs lol. It had very little torque.

By contrast, the celica, which has a 3sgte engine, is very torquey, but also has a great top end. It too needs the higher end of the rpm range to get into it's stride, but below that, it's got good torque, as long as it's high enough to make usable boost. Under 2,500rpm it doesn't, so it feels very sluggish. Once it hits about 2,600-2,700rpm the turbo comes on quite strong, and there is a massive surge, which isn't power, it's torque. You then ride that wave up to over 4,500rpm, where it gets into it's power band, and keeps going from strength to strength until 7000rpm.

Both cars had peaky engines, but where the corolla just lacked torque, and had a very linear power curve, the celica has torque in spades, but only once the turbo spools up. If the rolla dropped down below 2,500rpm mid corner, it would be bogged down on exit, but it's acceleration would increase as the revs rose. If the celica dropped below 2,500rpm mid corner, it would feel like a huge hole in the torque, and it would struggle for a couple of seconds, before suddenly lurching into life with explosive power.

It's hard for me to explain, but I hope that helps lol.

Hi Mike

I had a 2 litre WRX for 5 years. It had horrible turbo lag until I tuned it (chip, TBE) which fixed most of the lag, but not quite all. I've also had a series of tuned NA cars, so I know what you mean about power bands.

The turbo lag I was talking about in GT6 seasonals was for street Subarus on dirt, so no anit-lag. I do remember being quite surprised. But the more I think about it it might have been in GT5! My bad.

 

[Mike_grpA]

Yeah a stock turbo with a big turbo back exhaust hanging off it will spool earlier. I can't say I've noticed any lag on the subis on gt6, but I don't drive cars stock on gt6. All the cars I have on gt6 are fully modified, and logic dictates any car with a massive turbo will have significant lag, unless you live in the anti-logic world of gran turismo lol.

Me and a friend of mine actually were joking around about "real world gt auto" the other day. Saying stuff like "Oh hey mate, I was just wondering how much it would cost to turbocharge my car". "was it turbocharged standard?". "no". "Oh, sorry mate, nothin' we can do... We could give you an oil change, guarantee you an extra 100hp" lol this went on for hours haha.

 

[CSLACR]

and there is a massive surge, which isn't power, it's torque.

Missed that, looooooool. It's amazing how many car enthusiasts fundamentally have no idea what horsepower is.

 

[Mike_grpA]

Missed that, looooooool. It's amazing how many car enthusiasts fundamentally have no idea what horsepower is.

Yeah I know. You nail the throttle and the car puts them back in their seat and they're like "wow it's got some power!". That's not power you're feeling there mate lol.

 

[CSLACR]

Yeah I know. You nail the throttle and the car puts them back in their seat and they're like "wow it's got some power!". That's not power you're feeling there mate lol.

Yeah, they should make something like torque-per-minute, something that tells you how much torque is being delivered to the wheels in total, every minute.

 

[Sick Cylinder]

Yeah, they should make something like torque-per-minute, something that tells you how much torque is being delivered to the wheels in total, every minute.

1 Horsepower is defined as 550 foot pounds per second.

 

[Vegard]

1 Horsepower is defined as 550 foot pounds per second.

Awww, you sprung the trap...

Nice avatar BTW.