The Technical Questions Thread

[LeonOfTheDead]

My thesis was a bout hybrid cars, from a critic point of view.
Point in case is, compared to standard and similar cars (like with the Civic and Civic Hybrid), half of the hybrid version's improvements in mileage and emissions is achieved trough other features, as seen with BMW's EfficientDynamics and other similar systems from other manufacturers.
So definitely confirming what Culver said.

Another result was that the costs and the higher technical "difficulty" of full hybrid systems aren't exactly worth it despite providing better mileage and emissions levels compared to mild systems. On the other hand, mild systems seems simple anc cheap enough to waste some time waiting for EREVs like the Volt, or the Fisker (want).

[Commodore GS/E]

I know this is a stupid question, but...
i recently read about a really huge GM straight 6 petrol engine, produced mainly for GMC. The thing is, a friend of mine (he has a Commodore, too ) wants to replace his engine with a bigger one, and he won't choose anything else than a straight six. We searched long but weren't able to find an engine like mine (a 4l Irmscher block), so i thought we could use a GMC engine (as GMC is a part of GM, it should technically fit into the car). My question here: do you see any substantial problems with that? (Wikipedia says it has 302 cui^^)

[fpv_gtho]

GM and GMC being linked will by no means make the engine fit. Youre just as likely to fit an engine from any other brand in as you would a GMC engine IMO.

[group c n b man]

Only geeks will probably know the answer to this. Why did the SuperTouring engines of the 90s have about 15% percent more power than S2000 cars? Both displace 2.0l, have a rev limit of 8500 revs and you'd think that the big technical advances over the last decade would allow more power to be extracted. The average power for a modern S2000 touring car engine is between 270 and 300bhp. The average power for a SuperTouring engine was about 320bhp I believe, although not many actually proved this. Upon a closer look at the different regulations, it shows that SuperTouring engine regs were slightly more liberal than S2000 but not very (free flywheel design etc.) Is this the answer?

[Matra et Alpine]

Not sure, but checking some of the S2000 the regs ...

"Must be for sale at a maximum price of €168,000"

The last of the UK Touring Cars to the SuperTouring regs were upwards of £250,000

So I suspect simple economics

There is a limit on compression ratio of 11:1 in S2000 and valve lift, but I can't find the last regs used in SuperTouring ( I'm tryign to source the UK ones ), Again, if original formula didn't limit the compression ratio or lift then that's a clear candidate for a reason.

[group c n b man]

Not sure, but checking some of the S2000 the regs ...

"Must be for sale at a maximum price of €168,000"

The last of the UK Touring Cars to the SuperTouring regs were upwards of £250,000

So I suspect simple economics

There is a limit on compression ratio of 11:1 in S2000 and valve lift, but I can't find the last regs used in SuperTouring ( I'm tryign to source the UK ones ), Again, if original formula didn't limit the compression ratio or lift then that's a clear candidate for a reason.

Super Touring Register
compression ratio is free.

[Matra et Alpine]

Good find. So that'll be the difference then.
You can guarantee that with no limits back then they'd have been pushing the comp real high

[group c n b man]

Good find. So that'll be the difference then.
You can guarantee that with no limits back then they'd have been pushing the comp real high

That was what I meant by the rules being slightly more liberal. Free flywheel, free comperssion ratio, free pistons and a few more things which are somehow restricted on S2000 cars. Tom Chilton said in EVO back last year about the supertourers that "The engines screamed so hard it seemed impossible they wouldn't blow up". The truth is, many of them did especially Renaults and occasionally Volvos. Others like the Nissan Primera were very smokey on the overrun, probably due to a very rich mixture.

[Matra et Alpine]

Old race performance trick
Don't install a scraper ring on the pistons.
Much lower friction at the cost of oil use and emissions
Modern race liner treatments make this less of a setup-up.
You still see the Primera at the occasional event at Knockhill.

[group c n b man]

These engines must have had virtually no longevity. Even the modern S2000 BMW engine needs rebuilt every 1000 miles tops! These engines cost about £100,000 I think I read somewhere. The new NGTC turbo engines should be much cheaper and more reliable despite having the same power. Obviously, 300bhp from a 2.0N/A is very difficult and costly but 300bhp from a 2.0Turbo can't be too hard to achieve.

Do you know what times the Primera does around Knockhill? Last year at Knockhill the BTCC cars best laps were in the region of 53 seconds. I know that the ST cars were more powerful and lighter but damping technology has moved on a lot since the 90s. According to Tom Chilton "The modern car gains over kerbs and braking" and you'd think that the nature of Knockhill would be favourable for the newer cars.

[Matra et Alpine]

Tyres have made the biggest differing at Knockhill.
Sadly comparable times are difficult as the hairpin was remodelled 2 seasons ago and the chicane made "safer to cut" over the years

So with that in mind ...

11 years later on

David Leslie and Laurent Aiello raced in 1999 in the Nissan Primera GT.
Fastest lap that year went to Aiello of 53.024

Current BTCC lap record is 53.283 - Darren TURNER - 2008

I would say the "new" hairpin is good for a second a lap and the chicane about 0.5.

THey really were great times to watch and be involved in racing

[johnnynumfiv]

I recently read an article about an asphalt oval stock car running a 2 speed powerglide automatic. But instead of having a torque converter, it was bolted directly to the engine. How would that work? Wouldn't the car just stall when put into gear?

[Matra et Alpine]

Push to start and stall when stop.
With a big torquey engine it'll cope.
Not one for a small capacity turbo
It would seem workable on an oval.

[johnnynumfiv]

You'd probably have to rev and engage into gear to prevent the initial stall. Then shift to neutral when you want to come to a stop right?

[Matra et Alpine]

You could push start it in first gear -- all depends on the compression ratio and gearing, but assuming "lazy V8" ( INCOMING ) then would be easy.

Or, more likely, as you say knock it into first and on stopping into neutral.
Just not sure the effect that will have on wear/stresses in an auto box ( as you likely aware ... I dont' do AUTO )