Wanted Info On Front Mount For R33

[insu]

I suppose however, that on a completely stock skyline, the stock intercooler would have an efficency close enough to a FMIC for the purpose of producing the power made at 'stock'. Furthermore any advantages made by lowering the charge density of the air from a FMIC would probably be outweighed by the difference in the 'lag' time taken for the turbocharger to increase the pressure in a larger area.

So in that respect Paul, I would agree with you. I wouldn't see how just adding a FMIC would increase power (unless you had other mods like exhaust, upped boost pressure etc).

[S1R33]

I just picked up my blitz boost controller from autobarn today, f*ken whole manual is japanese, there goes the auotbarn sales talk 'it wll bolt on, just read the manual'. I ordered a Hybrid front mount intercooler kit through them yesterday as well, got if for $890 inc freight to Darwin, not too bad, could have got it cheaper but i get a local replacement warranty etc. MODS are coming slowly

[locosam]

When i installed my front mount, the biggest thing i noticed was the lack of throttle response. Running the same boost i thought that the car was a little slower overall.

Turning up the boost sorta overcame that problem, but throttle response wasnt there. When boost hit though, it felt faster (since i was running more boost), but from my experience with a FMIC, ive come to the conclusion that a fmic is a support part to allow you to get more power.

I still need tuning though so maybe my opinion will change after that.

So pretty much what paulr33 said is spot on.

What youll get is more lag, less throttle response and worse fuel economy, but you get the potential to make more power in the end.

my fmic is a greddy v-spl

[paulr33]

someone agree's with physics, hooray

[grigor]

Physics hey? Boyles Law, Charles’s Law etc.

P1V1/T1=P2V2/T2

I’ll borrow some numbers from FMIC tests for a RS500 and pick a boost of 15psi.

Turbo air temp was 135deg C. (408 deg absolute)

After the cooler the air temp is 35deg C. (308 deg absolute)

So the turbo pumps 15psi x V1 at 408 deg absolute.

After the cooler we have either 0.75V1 at 15psi or V1 at 11.3psi.

Sure there is air flow resistance in the pipework and heat soak for a sustained load, but the numbers demonstrate you get more denser air.

Most errors happen in wastegate pressure readings.

An Rb20 takes the wastegate pressure straight from the compressor housing so it doesn’t know what is happening in the plenum. It will spool up fractionally faster but now there is a lot more volume to fill so it’s a bit laggy.

Once the initial surge has levelled out, the plenum pressure will be lower than normal, but it will be filled with denser air so the net result is similar power, with a nice anti-detonation safety margin.

The Rb25 takes its wastegate pressure after the cooler, so you’ll get more air in the plenum due to the increase in air density. Again it will spool up slightly faster and it will have some lag, the plenum pressure will read same as before but it will now have a more dense air charge. The turbo has eaten more air and the AFM is out of sync with the parameters set up by Nissan.

Without altering the tune via a PFC etc, the AFM will sense the larger air flows and start to dump in fuel. Stop/start conditions are the worst as it’s continually fuelling for unrealistic air flows, the black-bumper syndrome.

If you add some other factors like a cold evening and no air temp compensation, I’m sure that’s why so many slightly modded Rb25’s experience the R&R which ends in the Ignition/Fuel cut and the poor old coil-packs cop the blame.

Regards.

[nsta]

Cool thread, just got a boost tap, and while i cant run much boost at the moment, when i do tap it up a little,i experience severe missfiring in gears 2 and over????, will a front mount help?or is it more a fuel issue?