I motori americani fanno schifo....

[TonyH]

O forse no?

Sull'ultimo 4R c'è un bel servizio in USA (fanno la strada dei Pony Express....è un viaggio da fare nelle vita ) con 3 "pony-car" tra cui la Camaro SS

V8 6.2, 426cv....pure stile USA, parrebbe il solito motoraccio...ma poi...lo confronti con "lo stato dell'arte europeo" (997 S PDK) e scopri...

0-100km/h: 4.6 per l'americana, 4.4 la Porsche

0-400m: 12.9 - 12.5

E fin qua direte "vabbè...con 426cv...ma chissà quanto consuma!!". E qua viene il bello:

consumo cittadino: 6.7km/l la Camaro, 6.5 la Porsche (!!)

autostrada: 10.1 contro 10

E in più...loro fanno il cambio olio al wal mart con normalissimo semisintetico....e hanno pochissime minchiate che si possono rompere

Tacciamo poi dei prezzi di listino: 50.000$ la Chevy....per l'altra....fate per 2.......

Non avranno le rifiniture premiummmm.......ma onestamente....avendo visto la prova, mi sento un pò coglione........

[ACS]

Tra il V8 AMG ed il V6 COMPLETO di GTR non ci sono differenze di ingombri di rilievo che ti debbano far ripensare gli ingrombri di qualsiasi auto...

Il V6 HF 3200 di GM in versione TT eroga 430cv e pesa circa 87kg in più di quello montato oggi su 159.

[Matteo B.]

Tra il V8 AMG ed il V6 COMPLETO di GTR non ci sono differenze di ingombri di rilievo che ti debbano far ripensare gli ingrombri di qualsiasi auto...

.

[TonyH]

anche qui non siamo d'accordo ACS. un V8 grosso è ben più LUNGO e la lunghezza è una bella fregatura quando devi posizionare le sospensioni.

[Matteo B.]

l'intercooler però più o meno lo metti dove vuoi.

la larghezza (parlo di longitudinale) oggi non è un problema dato che le auto per tanti motivi devono essere larghe.

gtr BORE : 95,5 x 3= 286, 5

AMG BORE:102,2x4= 408, 8

ok la maggior distanza tra un cilidro e l'altro, ma è un' altra cosa da verificare per benino.

[TonyH]

l'intercooler però più o meno lo metti dove vuoi.

[Matteo B.]

mhh....temo di no...

da gtr.co.uk

Nikasil spray coating which is on bikes, F1, etc is what you are describing, and is a trademarked electrodeposited oleophilic nickel matrix silicium carbide coating for engine components, mainly piston engine cylinder liners. It was introduced by Mahle in 1967. It is basically bullet proof expect when in the presence of high sulphur fuel (>350ppm), as the sulphur has a higher affinity for silicon than nickel - Jag and BMW suffered this in certain high suplhur markets, but most 1st world markets are now down at <50ppm sulphur level. We recommended to Nissan to go this route, but it does have some environmental issues during manufacturing, and people are still nervous after what happened to Jag and BMW.

There are virtually no applications that use plasma coating in racing or otherwise as Nikasil is so easy to do and is extremely robust. The GTR uses a plamsa sprayed iron coating, almost certainly applied using the Ford PTWA process (at least the blocks we did were). If it is applied using this process then it is probably the first ever application using the PTWA method in production (there are other methods such as Plasma from Sulzer Metco, but most still consider it not robust enough yet). Cleanliness of the parent bore before application of the iron is absolutely key, and it does not bond well if there are any problems. Also, when pushed too hard it will peel small strips of iron off (the coating is pretty damn thin), normally at the top ring reversal point, or higher if the edge of the crown contacts the bore.

"Plasma coating generally has a much lower coefficient of friction compared to cast iron".....probably not much different as it is also iron, "and has substantially better wear characteristics", not really again as is the same stuff expect thinner, "so I'll be interested to see what the piston rings are composed of"...the same ring pack and piston coatings are used as a standatd engine. Actually, for the GTR, the rings had a very tough time so the top ring has a better than PDV coating (can't remember is name, but could find out), with a positive twist too! The plasma spray effectively gives parent bore which is mainly done to improve heat transfer characteristics and save weight.

We had failures during development but we did bore them out and re-sleeve with iron liners (2mm thick). However, our blocks were originally designed to take 2mm iron liners, and thus the aluminium thickness to the water jacket was 6.5mm nominally when parent bore....with the liners fitted this obviously becomes 4.5mm of AL and 2mm of iron between the outside of the cylinder and the water jacket. For a fully optimised parent bore solution (to improve heat transfer) the water jacket should be moved in 2mm so it becomes 4.5mm from the outside of the cylinder to the water jacket....this means that fitting liners would be pretty much impossible without damaging the water jacket in some way (pressing the liners in would probably crack the wall that is left between ***** and water jacket, leading to internal water leaks....the water will find it's way out).

Distance between cylinders (bore spacing) is not a problem even though it has siamesed bores (no water between bores), although there is probably a cross drilling between bores. Parent bore does enable engine to be made smaller, but for a 60 deg V6 the benefits are marginal as the engine geometry is always governed by the fact that you need a flying web on the crankshaft between opposite cylinders to maintain even firing.

EDIT : dati del V8 AMG UFFICIALI 102,2 BORE distance between cylindres 109 mm 109-102,2 =6,8 mm.

Modificato 29 Novembre 2009 da Matteo B.

[TonyH]

Nella pappardella inglese non riporta l'interasse.

Parla di tutto, tranne che di quello!