Unichip and Boosts

[Jet]

I got unichip installed my car ( Gtst R33) and the dyno shows 155rwkw @ 13.5psi. I am running on an standard intercooler. Although I got a proper cold air partition and an water spray for the intercooler, I still think I am running too much boost. But the guy who tuned my car says theres no problem at all. Should I trust him?

I only drive the car hard at night or cooler days. will I have the problem of overboost and break my pistons? or the guy who tuned my car has tuned the car to suit that boost? and pro can give some suggestions?

[YBSLO4]

Is it a mechanical bleed valve or electronic boost controller? If it is a bleed valve then definately be bloody careful. Nissan turbo seals are only rated with a maximum pressure of 14psi before they do the turbo exhaust seal. Not to mention they have a plastic impeller fan :S Problem with boostin gon a stock cooler is the pressure loss in the stock cooler on skylines is not that good so if you are running 13.5psi at the manifold then more than likely your turbo is pushing about 16psi or even more depending on amospheric pressure and ambient temperature outside to actually make that kinda boost at the manifold. I suggest ya get a new cooler before ya go passed 10psi. If ya not gunna run a cooler then turn it down a tad. Also depends on how heavy ya foot is as to how long it will last.

BTW what mod's u got? cos with that kinda boost and a UniChip ya should be pushing more than that with light mod's dude... my mate on his is running same as me, exhaust filter bit a boost and fuel pressure reg and is pushing 187 at the wheels untuned? (i havn't dynoed mine yet).

[HoeTrain]

My car dyno'd at 153rwkw with only a filter, exhaust, slight boosting. As YBSLO4 sugested, I'd wack in a FMIC, it will make a difference.

[Jet]

YBSLO4, I only got pod filter and 3.5inch cat back exhaust. I think the dump pipe is standard. nothing else apart from that. Maybe I should reduce the boost.

but do you think that the guy who tune the car would map the engin so it would suit that kinda boost? or it wouldnt make any difference.

cos a intercooler would cost me another 1000 bux. and there would be more things I should worry about if I go over 170rwkw. like clutch, breaks, etc..

i dont plan to drive the car for long.

[Gold Rays]

Yea I agree YBSLO4, if i was you i wouldn't be turning the boost past 10 psi otherwise your engine will start detinating, which could put holes in your pistons.

You should finish off your exhaust first, as in get a high flow cat and a dump pipe. Then go the cooler. That way you get your car breathing properly. Your stock breaks are fine unless your doing 200 plus or your on your breaks all the time.

[Sydneykid]

Hi Jet, there are two problems with the standard turbo, both centred around the ceramic exhaust turbine.

Firstly, being ceramic the turbine is sweated/bonded onto the common shaft and therefore it does not like too much resistance ie; the exhaust is pushing the turbine while the compressor is trying to move air into the engine. Too much resistance (boost) and the turbine and the shaft part company.

The second problem is one of heat, the ceramic turbine will only handle a certain amount of heat coupled with this resistance. The heat builds up over several minutes of very hard driving (say on a circuit) and the turbine shatters or parts company with the shaft. Leaning out the engine to achieve more horsepower also increases the temperature of the exhaust.

So to answer your question, our experience has been that 0.8 bar (12 lbs) is OK for a road car as long as it is only in short bursts so that the heat does not build up. If you do any circuit work or long distance high speed stuff, then 0.7 bar (10 lbs) may well be the safe max.

With a really good intercooler and pipes we have achieved 0.8 bar (12 lbs) on a 200 RWKW road car reliably. But 5 hard laps on the circuit and the smoke escaped.

If the tuner did a proper job there should be no risk of detonation regardless of the amount of boost. I have tuned internally standard RB25DET's for 2 bar, without any detonation. It is simply a matter of balancing the airflow air fuel ratios and ignition timing.

Dyno's all read differently, so I wouldn't worry too much about the absolute max horsepower. If we assume that the 155 rwkw is reasonably accurate, I would say that he has tuned it fairly conservatively. Rich A/F ratios and a bit of ignition retard.

Bottom line, I don't believe that detonation is going to be a problem, but turbo life certainly is.

Hope that helps.