vosko

that little HT18 isn't moving much air at 19psi.....and its gonna start puking oil soon but 550x4 with correct tuning should be able to give enough fuel for 20psi. there are so many factors!! you have to check your fp with a gauge. hopefully your injectors are clean etc. my old T2 lasted two days @ 15-17psi but i did have a T04 upgrade on it so it was pushing more air than a stock turbo

j9fd3s

its depends, the 20b has 550's all the way around and its running around 12:1 afs at 75% duty @12psi, so theres more injector. the austrailians run the stock injectors at 15psi all day long. if you have the stock turbo the difference in flow between 15 and 19 psi might not be much, i know on the 20b i'm maxxed out around 12-13psi, 14psi doesnt need any more fuel.



of course if you do have a stock turbo look for it to die really fast.



you might take some timing out and add some fuel pressure if you can, with the injectors maxxed its gonna be leaner on a cold night



mike

1Revvin7

Yea you can run more than 11psi, but you'll go lean fast.



I have drove a t2 at 15psi, with just a fuel pump.. Guess what? It blew a week later....



If you think im full of ****, go ahead run 19psi on basically stock fuel system, LOL [/quote]

My car has ran at 15psi for a good while and its still running strong.





And I did run 19psi. It felt really nice. I wanted to do it some more but thought better of it. [/quote]

I wish I could afford to experiment like that



"Cartech found that the large injectors and the aggressive fuel curve afforded by the stock EFI rendered a correct air/fuel mixture to a level of about 8 psi without lowering discharge temperatures; with other improvements, it was possible to run safely to the 11 psi range before additional modification to the fuel system was required. "





Grassroots Article



These guys know what they are talking about.. But then again this was with a stock ecu, I bet the stock ecu can't push the injectors past 65% duty cycle, or maybe i'm just wrong...

But this got me curious, I believe 550 x 4 x 85% s/b enough fuel for about 280rhwp... stock motor/turbo 280rhwp would be near like 17psi...

Can you get on a dyno or do you have access to a wb o2?

j9fd3s

the stock ecu will run something around 85-90% injector duty, but it also runs a lot of timing



mike

djgiantrobot

my infornation is based on my own experiences while tuning. At 10psi past 6k with stock injectors and a standalone, i was seeing A/F dropping lower than 12.5:1 which is getting a little bit on the dangerous side in my opinion. Past 10 or 11 you aren't making much more power just more heat, I am running a front mount also and i wouldn't run my car past 6k until i had larger injectors.

Rotaryman88

adaml...can i buy ur car RIGHT now, dont drive any more...I just want to save a S5 TII

adamlewis

Yea you can run more than 11psi, but you'll go lean fast.



I have drove a t2 at 15psi, with just a fuel pump.. Guess what? It blew a week later....



If you think im full of ****, go ahead run 19psi on basically stock fuel system, LOL [/quote]

My car has ran at 15psi for a good while and its still running strong.





And I did run 19psi. It felt really nice. I wanted to do it some more but thought better of it. [/quote]

I wish I could afford to experiment like that



"Cartech found that the large injectors and the aggressive fuel curve afforded by the stock EFI rendered a correct air/fuel mixture to a level of about 8 psi without lowering discharge temperatures; with other improvements, it was possible to run safely to the 11 psi range before additional modification to the fuel system was required. "





Grassroots Article



These guys know what they are talking about.. But then again this was with a stock ecu, I bet the stock ecu can't push the injectors past 65% duty cycle, or maybe i'm just wrong...

But this got me curious, I believe 550 x 4 x 85% s/b enough fuel for about 280rhwp... stock motor/turbo 280rhwp would be near like 17psi...

Can you get on a dyno or do you have access to a wb o2? [/quote]

Yeah. Im taking it to a dyno this friday. Its going to be running 15psi then.

adamlewis

I can personally testify that going from 11->15 is a very big difference in power. at 15psi, my front end starts to get light and itll lock my seatbelts from a roll in 3rd.

adamlewis

Please This car has been saved already.



The only thing different about the way you and I work on our cars is that I actually push it to see what it can do instead of just taking someone elses word without any real proof...

adamlewis

Yeah. Like I said, Ive been running 15psi for a while now and have absolutely no problems. No low compression, no smoke under boost/vacuum, perfect rock steady idle, no shaft play...I mean the car is perfect.



I think the car is tougher than you all think...

And Ive still yet to see any real data about how much air the HT-18 flows...Or how efficiently it does it.