I am new to evos and I am sorry if this is a stupid question but what are the weaknesses of the evo powertrain when boost is raised?

For example, on 350Z's rods seem to be the weak point just north of 400rwhp, then you get head lift problems once you get really high as well.

Another newb question, just to get it out of the way, but on the VIII, what kind of boost is the stock turbo capable of flowing efficiently? Similarly, at what power goal range does one have to start considering the need for a new turbo?

 

You can probably max out the turbo before seeing engine/tranny failure problems. The stock turbo is good for ~22-23 psi on pump and good for ~350ish whp without alky or meth.

 

so i can raise the psi to 22-23 without having any problems and make 350 on the stock turbo?

 

lol....you can make 350WHP on the stock turbo, but you have to do a lot more than just up the boost. Look at all the mods in my sig, before alky I had 350 WHP & 350 WTQ.....on a Dynojet.

 

more air needs more spark and fuel.

 

TTP push to 34.5 psi and run 11.2!!

 

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QUOTE=sabrefanpc]I am new to evos and I am sorry if this is a stupid question but what are the weaknesses of the evo powertrain when boost is raised?

The crank is decent however the cast pistons and rods are questionable once you start really stretching the envelope. A lot of guys do head studs which'll save your headgasket but doesn't do any good at the bottom end, where others'll upgrade to ARP rod bolts, as minimum insurance.

There is a thread a few weeks back about 500 WHP stock block engines, so it has been done but you'd better have a righteous relationship with a good tuner and boodles of high octane gasoline.

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Another newb question, just to get it out of the way, but on the VIII, what kind of boost is the stock turbo capable of flowing efficiently? Similarly, at what power goal range does one have to start considering the need for a new turbo?

There are racers who'll take the stock turbo to 30+ p.s.i. on race gas and 27+ on pump gas with Alky. On 91 octane you probably don't wanna do much more than 22ish. On 93 maybe you can flirt with 24 if you have a really righteous tune with optimized timing and fuel tables.

There are fellows like CBRD, TTP, Sean Ivey, and Dave Buschur who've explored the stock turbo's upper power limits and it's a bit above 380 WHP without Alky. Maybe the stock turbo has even been over 400 w/o drugs(maybe?). But these are really exceptional cases carried out by topnotch tuners with standalone ECU's and fully ported heads and radical high lift cams.

At these power levels over 370-380 the stock turbo really becomes a restriction and is blowing a lot of hot air and is just way beyond its optimal efficiency range.

Edit: Oh, I forgot to mention that you aren't gonna be able to transmit these types of power levels through the stock clutch either.

 

Remember u jus cant raise the boost. U have to a tune before raising the boost on ur Evo