I have researched and read many posts where people say the maximum amount of boost our xB's 1NZ-FEs can handle is 7.5 - 8 psi without breaking anything internally. But when you compare that to what the echo and yaris guys are saying, I have seen anywhere from 10 to 15 psi on stock internals, it seems like there is no proof of what they can actually handle. I would like to know if this value is just an estimate, a calculation, or is there proof of 8 psi being the limit. I just don't think that 8 psi is the limit these engines can handle with a stock bottom end. I say this because I have been running 10.5 psi now for 2 weeks and the only thing that I have broken is the stock clutch. I do currently have a very mild tune though, only 131 hp and 159 ft/lbs. Therefore my question is, is there any proof of the amount of boost a 1NZ-FE can handle?

 

over a longer period of time your going to show wear signs of the engine not doing so well. i think most of the post your seeing that are 7.5-8 psi are the safe zone. any higher and you really are pushing the limits of the engine to have something break much sooner.

the ohter part is proper tuning and fuel managment.

 

actually, it seems that the drive axels go before the engine will. i think 230 whp is the limit of the drive axles, don't know how much boost that is, but yeah, that is what happens first, so long as the tune is done right.

 

The rule I always hear is 10hp per cylinder is safe on almost any car, so a 40hp gain over stock is ok (130-140hp). The boost you are at seems ok but once people start going over 10psi they seem to start having lots of problems with the 1nz-fe. I say play it safe keep it at a good tune and dont go any higher without forged internals.

 

I am definitely going to keep the tune very mild to see how the engine holds up for a while and depending on how it performs, I will or will not put more of an extreme tune on it, hopefully about 180-200hp. I am in the process of finding forged rods and pistons to build my spare engine, which is more dificult than I had hoped.

 

The type of failure that occurs from running high boost over long periods of time is a fatigue failure. The reason no one can tell you how long it will was at a specific boost is because fatigue is hard to exactly predict, it involves alot of satistics and testing. With steel there is a certain stress value called the "endurance limit," where you are considered to have infinite life, or until it fails in a different manner. Once you pass that "endurance limit" you take away at the life, shortening it. My guess is that toyota keeps the engine rods under the endurance limit, but to be cost effective im sure its not that far away. So by increasing boost you in turn apply more stress pushing the rods pass there endurance limit and causing a failure due to fatigue. The time can be anywhere for 10,000 cycles to 10 million cycles. You can estimate the time it will last but its a pretty difficult stress analysis problem and you always have an error of +- 10%. Sorry if I confused anyone, just goes to show you that it is a guesstimate type of answer.

 

someone had his xA at 14 pounds and retarded the timing....simmo i think

 

Really ? Only 131hp at 10psi? I was running 7.25psi on mine because I have seen what happens when you push motors too hard.. Just ask Viet. He blew his motor up with N2O and a blower all over the track.

 

for long term safety at that higher boost I would get internals...these are economy motors....

 

if i was to boost my xb, i would only run 5-6psi. thats just me tho. these little 1.5L aren't made for boost. but on the flip side.. i've heard of people boosting 15psi in thier xb.. thats just crazy to me.

 

boosting is too expensive and not enough gain for an xb it doesnt make sence to drop 3 g's into the box nd still get waxxed by a stock tc or any honda.. if i was gonna go boost i would have got a car with more potential like an rsx. i just cant justify dropping all that money and not being able to achive 200whp

 

Thats where your wrong. You can achieve 200 whp if you know what you are doing. You should have done some research before posting. A turbo xB can can beat a supercharged tc and there is a video of it on youtube.com.

 

you can also boost for WELL UNDER $3000

 

Agreed. The guy with the supercharged tc in the video on youtube is from Nashville and I know him well and we will race soon. I am sure that he will win, but I am only at 130hp.

And agreed! I am not even at $2500 and that includes a new clutch...

 

IIRC, the problem with boosting these engines is in the economical design. The crank is slightly offset to provide an economy bump, but when boosted, this offset is the weak link in the engine.

Nastos, it's not about making the xB the fastest car, just making the xB faster...

 

Yea, I mean, an extra 40HP in the box would make for a LOT of fun! It doesn't have to be the fastest car out there, but it would definitely be quick.

 

typical SL comment. U odviously dont know what ur talkin about.

 

You will be lucky if the axles go even hold all the hp. Anyways you cant just go by horsepower numbers I mean our cars arent that heavy so 180hp could rocket these little things. And spending 3-5k is not bad a price. Look at other turbo kits for diff cars you will be paying a lot more money. And there are turbo xA out there smoke mustang GTs...like someone said probaly should research your ____ before you post goofy statements.

 

Its been tested that the axles can hold up to 230HP.

 

umm what dont i know? it was a opinion its an economy car not made for the high preasures that other engines can handle a typical sl reply to a typical sl post lol