20G Turbo on a 420A... Will it Spool?!

I just purchased a turbo. it's a Super 16G turbo that has been ported to a 20G... Or atleast that's what I was told (he didn't have any machine specs). I'm going to have a full 3'' exhaust and I'm running it at 7psi (stock internals). When can I expect this to spool with no other mods? Thanks!

sounds like a lotta lag to me

you have a stock exhaust. ^^ theres no telling how long that will take. Do you have everything to run that on your car? Correct me if Im wrong but he will need an a fmic to run that size turbo on his car.

What kind of car would it be mounted on ? I am assuming its a RS/GS from the post title but what mods do you have on the car ? Are you using a custom or Hahn manifold ? Stock internals, no intercooler,stock fuel pump,blow off valve?! You wont be expecting much horses at the wheels. It would pull like crazy for a 420a, but I suggest you get atleast a fuel pump, blow off valve and a intercooler. Then you might run at 10psi, and your car would love you.
Dont blow your engine, after all its stock internal you are running on, and I know you wanna hear that turbo spool :) Put the 16G on and post how the 420a is performing compared to before. Good luck.

Displacement has the largest effect on boost threshold for a given turbo. A 2 liter NT and 2 liter 4g63 have the same displacement. Expect similar boost threshold numbers. On a turbo motor, a TDO5H 20 will hit 25 psi at ~3500 rpm, and a TDO6H 20g will reach 25 psi around 3700 rpm. There will be some variance with the NT motor, but I don't expect it will be huge. The HRC "super" turbos do use 10cm turbing housings compared to the more typical 7cm housing. That will have a significan effect on lag. Can't say how much though since I have never run a 10cm housing before. And I dont think a 20g at 7 psi will require a FMIC. For what its worth though, there will be no difference in power production between the 16g and 20g at such low boost levels, especially if they are both 5Hs. The lag difference would be noticeable though. Hardly worth it, unless this is to provide capacity for future use.

Here's a list of some of the things that I have that've been mentioned:
HRC exhaust manifold
Walbro 255 fuel pump
450cc injectors
HUGE FMIC
3'' Exhaust (Might just dump after that cat)
BOV

I have a decent amount into this setup, and yes... It's been put together with the intent for future engine mods.

So what kind of boost do you think I could safely run with stock internals? 10psi on a 420A?! Would water/alcohol injection help make this possible? Thanks!

hummmm.

Single most important part of building a turbo system is stable, reliable, fuel delevery. that would mean FP/rewire, aermotive filter, afpr, gauge, -6an return lines. Thats ontop what you listed.

FMIC with 10psi will give you nothing but major pressure drop...

Pick up two books

Coorky Bells: Maximum Boost
Jeff Hartman: How to Tune and Modify Engine Managements Systems (FUCKING INCREDABLE)

I have everything listed above for fuel mods. How do you solve the pressure drop problem with 10psi and a FMIC? I'm having this tuned professionally, so that may help out a lot. I'm still going to check out the books though. Thanks!

Well first of all; Are you telling me you have all the Supporting fuel modifications that I listed? Or you listed?

It just dosn't make sence to have a 20g (ported out 16g) turbo @ 10psi on a stock 420a. thats like giving a baby a 2 liter of Pepsi.

You will solve the problem of pressure drop buy understanding what it is... Search for it on Google. It's just to much to type out.

Pressure drop really only matters when the turbo is maxed out though, IMO.

He will still notice an increased lag. More volume, more lag.

Can you quantify the added lag though? I don't believe I have ever been able to measure it. Small turbos make up the difference in such a small amount of time/rpm... Or in this case a medium sized turbo at ridiculously low boost for it's size. Just playing the other side to keep the conversation going, I have no hard evidence to support my theory. :)

Isn't 10psi a little high for a NT engine that has not been built? I don't know (or care) about the internals of the 420a engine, but I would assume they are not up to the task of supporting such an increase in pressure. As far as I have seen, most aftermarket kits stay around 4 or 5 psi on a stock NT engine. Also, a FMIC probably won't make a significant difference over a side mount at low boost levels. Since obviously the air will not be heated as much, (assuming 4-6 psi) it doesn't seem worth the additional cost.

Im not following you here. Are you saying that a huge intercooler, with as little as 10psi from a super16 wont effect airflow? I don't reamber the airflow formula for intercoolers off my head. But what i reamber is Design, Volume, Shape, Temp, Pressure all play into the effency formula.

Edit: had to look it up.

Lag: Time = (Volume / Flow Rate) * 2

Not really important. As I understand it, Pressure loss, Air Density, Lag, are all effected by the IC. Large intercooler, small airflow speeds should increase lag. If a compressor wheel is moving air at 60,000 rpm at 10psi their will be a specific volume, cfm based on that turbos compressor map that it will produce. The same turbo at 110,000 rpm with 20psi will have it's own airflow #'s. Wich one will fill the intercooler faster?

Im not following you here. Are you saying that a huge intercooler, with as little as 10psi from a super16 wont effect airflow? I don't reamber the airflow formula for intercoolers off my head. But what i reamber is Design, Size, Pressure all play into the effency formula.


I think he was talking about the FMIC being overkill for cooling the air. He said that it isn't necessary because at lower boost levels the air doesn't get hot enough to need to be cooled by a FMIC

I still say intercoolers will more than make up in power what they cost in pressure drop and all that stuff. Let's look at at example.

Assuming 80 degree day, 100 degree intake temps, sea level, 75% compressor efficiency, and 6 psi boost pressure, outlet temps are 177 degrees. Thats still quite an increase over the 100 degree intake temps... Add a front mount that is 80% efficient at 1 psi pressure drop, and temps drop to 99 degrees. If that isnt worth 42 rpm in lag for the added safety (knock protection) and power (denser charge, plus the ability to run more boost on the same fuel), I don't know what is.

Sure, the math is correct. Assuming he can produce 75% compressor effency at 6psi.

TD05H-16G Small max effency is 77% @1.4bar+
TD05H-16G large max effency is 71% @ 1.2bar+
TD06H-16G large max effency is 74% @ 1.3bar+
TD06H-20G max effenct is 77% @ 1.4bar+

Being unsure of what turbo he has don't help, I feel with as little boost he will run, and the heat generated from the wheel in intake temps he wont need a supper large, highly effecent intercooler. he might benifit from a good small sidemount untell intake temps increase dramaticly with boost. Besides that. 420a with a 16 or 20 has a good amount of lag, any decrease in lag on a "street" car helps. expecially one only at 6psi. To large of intercooler regardless of effency at 6psi on those wheels wont make any notticable power diffrence for the 600+ he will have to spend. Not cost effecent IMO. Sure Volemetric Effency,Air Density, Heat exchange play into sellection of an intercooler. But, at what point do you justify $600+ for the performance you will recieve on his specific setup?

I call it cheap insurance against detonation. But you may be right, and there are plenty of low boost turbo and supercharger kits that don't include ICs. They also run rich as hell to be safe too. I don't know, I think if I was to build a turbo NA car I would be using a FMIC. Granted it would not be the same size I use on my race cars obviously. A little shorter in length. A stock EVO8 fmic would probably be pretty good. Otherwise, something around 18 inches in length, but still tall and thick (since height and thickness reduce restriction at a give flow rate).