Hello !

Ive read somewhere here in the 2g forum, that the original turboII air intake box, is made in a way to act as a boost limiting device ( safety barrier from factory ) ?

Example : My car runs a full racing beat revII exhaust from turbo and all way back, FCD is mounted, and it has the stock air intake box/ air filter, no other mods, not even a portet wastegate.

Previously owner explained that when at one time he mounted a HKS cone filter intake, the car started to glow its downpipe, and run bad at wot in 4-5 gear, possibly because the car must have run lean / boosting to much ?

After that he replaced the stock intake box / filter, and the car was back to normal behaviour, and he drove it like this for several years, until i got the car.

So running the stock intake box / filter may act as a safety device ? Any experience on this .

thanks -

 

Nope. '89 TII-I have the factory stock intake, OE mufflers with a Bonez cat and pre-cat delete, G Force ecu, 3G fuel pump, Hallman MBC and have no problems hitting 12 lbs.

What boost are you seeing? Check to be certain the WG rod is attached and the boost solenoid is functioning.

 

safety barrier?..pure Horse Pucky!
Sorry man,That is like saying the tires are built round to keep air in and the dirt out.

 

Maybe the FCD is hooked up wrong or doesn't work as it should. Or maybe there's some sort of restrictor plate in the exhaust to keep boost creep down.

Have you tried driving it with the aftermarket intake? How does it pull as it is right now? What boost gauge are you using to read the manifold pressure, and what pressure does it go up to?

 

Thanks for the input guys !

Turbonut-misterstyx69-Agreen, im answering youre replays in the text below -


Today after posting here i temporarily mounted a mechanical Autometer boost gauge, with a T piece at the vacume hose for the Bov, then test drove the car running through the gears, both at low rpm - high rpm - high load etc etc.

Autometer gauge readings were:

2nd gear: highest value 8.0 psi
3d gear : 9.0 psi
4th gear : 11.75 psi
5th gear : 11.75 psi


Well as i understand this is to much pressure for the otherwise stock setup, the car feels and runs strong, with no hessitation throughout the rpm range, and it also has so the last 25k miles ( ref previous owner ) with this setup.

Im goin to hook up my Innovative wideband to the car in a couple of days, and check the AFR`s the same way.

By the way, the wastegate rod is attached - boost solenoid is not tested yet.

I have not driven the car with the HKS cone filter, i olny got it along with the car. Im keeping this stock s5 motor for periodical controll etc, so i need to get these boost levels under controll, the car will se a Cosmo 13bRE with singel turbo and standalone this fall, but until then the stock motor will be in the car.

 

Those numbers actually aren't THAT bad all things considered. What did you say the problem was again?

The stock air box is definitely an intake restriction, and without a ported wastegate, it is probably the only thing keeping the car from creeping and running lean(er).

DO NOT install that cone filter. For one it will flow freely and cause more boost, it will also suck in hot engine bay air instead of the (relatively) cool air of the stock intake making detonation far more likely.

 

+1

at nearly 12psi without knowing what modifications the ECU accounts for it may well be borderline popping. in fact, if the fuel system has been untouched that IS borderline too much for the stock fuel system. add in the TID and air filter and it will likely pick up a few more PSI and go into dangerous territory potentially costing you the motor.

install the wideband and get some figures to see how the AFRs are looking with the stock airbox in place and go from there.

the stock airbox is a restriction even on completely stock cars, replacing it with a TID mod you will notice more boost even on a completely otherwise stock car. the more you open up the intake and exhaust flow the more your timing and fuel needs to be controlled to compensate for it. that is why the cars had a factory 8.6psi fuel cut and a TID mod and cat removal would push it beyond that territory.

it wasn't an intentional safety device but you can consider it to be one, because removing it will reduce intake resistance and raise boost.

 

[redneck voice] Well there's your problem [/redneck voice]

I'm going to +1, just for added effect and more pizazz. The cone filter probably did push the boost into dangerous levels. After 10-12ish psi, the stock turbo just starts pumping heat, so that whole "running like crap and glowing downpipe" thing was probably destroying your engine.

 

Hello Hello !

thanks for the input guys, i guss it okay to conclude that on a " unhealthy" setup like this ( all stock expt for 3" exhaust and FCD ) its a positive thing to use the stock air intake box, so it`ll not unleash the last couple of deadly psi. As must have been the situation with the HKS filter.

To continue the use of the car, next will be wgt porting, i will post the wideband AFR readings when tested, for those interested.

Regards !

 

Just and FYI-Years ago I installed a Apexi cone assembly and found no difference in performace or boost, just a lot of additional noise from under the hood, so only on for 1 week and it was put back on the self in the garage and is still there.

 

the intake duct is the restriction most are referring to, i suppose that should have been clarified.

mounting the filter on the AFM with the stock TID won't make any real noticable result.

generally when you upgrade the filter you ditch the intake piping as well with it's steep curves and tapers, which gives an idea how easily the airflow leading into the turbo is disrupted by smaller diameter piping and curves in it. ideally a velocity stack works as a trumpet to direct air, or in most cases just larger piping straight out in front or no filter at all.

 

Updates :

- Ported wastegate ( fc3spro guide )

- Removed airpump

- Removed acv ( for now i just blocked the three vacumehoses that was conected to it, however maybe not idealy ) and just unhooked the electrical conectors

- dual alternator pully - to make sure the waterpump doesn`t slip.

conected bov-map sensor - boost gaguge to vacume source on the upper left on the uim which is originaly blockd with a cap.

Resault :

The car now runs a rock solid 6.0 psi at wot in every gear ( before 11.75 psi )
AFR at wot in every gear in the high rpms, is at 12.1 as richest , except when wot in 5th gear below 4k rpm, then its lean at 14.5 AFR

well, this is for sure more safe than the original setup ( 11.75 psi - stock wastegate) but its of course much slower.

any inputs ?

Thanks in advance

 

Sounds like it's running like it should be , but considering stock is 7.5 psi on s5 (89-91), i think you could probably run more boost with a boost controller as long as you have a fuel cut defender (s4 87-88 is 5.5psi stock) , but i'm not sure how much your setup would be running safe with, but as long as you have enough fuel and a fuel cut defender i think it should be able to handle 8-10 psi, but you might need an upgraded fuel pump (which wouldnt be a bad idea since you're upgrading the motor and will need one at that point)

Hopefully the other guys on here can give you some input as to what you need to do.

 

something is wrong with the stock electronic boost controller.

 

Update -

Stock boost controller solenoid cliks ( on- off-on - off ) at a pace of 4 times a second, at ign on, pre start, and idle.

Tested it as wsm describes:


: resistancec OK
: Opens when applied 12v

Maybe signal from ecu makes this on/off scenario ?

 

Did you mean 12.1 afr at the leanest?

 

Hello


No, not the leanest condition, but those were the values at WOT.

Richest then, that is the way to say it. Since fuel is what we need.

Thanks for input !

 

If it was 12.1 at the leanest, that means all the values were richer than 12.1 (<12.1)
If it was 12.1 at the richest, that means all the values were leaner than 12.1 (>12.1)

Big difference.

 

Yes - then it is as first stated.

12.1 as the richest condition at WOT at the given rpm's.

( >12.1 )

 

12.1 is should be fine for under 8psi. You should be thinking about some 720's and adjustable 1.1 FPR.

FCD, 720cc secondaires, cone filter on factory TID, full 3"exhaust should net 7 psi up to 2nd gear. 3rd gear up will do 9psi. 30 degree weather above third gear i saw 11psi. florida altitude.

That is my most reliable setup to date; With tons of drifting, autocross, and my only car with tons of extreme driving.. it lasted 4.5 years after i bought from some kid who had if for a few years and blew out the clutch. aND I meAN BLEW IT! SO it lasted well over 5 years of abuse.