[Ben]

I know the stock MAF can handle abour 230hp. A stock BB T25 runs 7psi works great with the stock MAF, but normally with 370cc's and a JWT ECU. I know the stock injectors are good for around 200hp. I know the NA guys have put out like 175whp with them and are ok.

As long as you don't up the boost, would this work and be reliable? $350-400 for the turbo, manifold, and exhaust elbow, $100 for homemade piping, and that's it. $500 to $600 for 200whp. Beats the HELL out of an NA setup. I'm tempted to try it. As long as you are running stoich (not rich and especially NOT LEAN) then I don't see why it shouldn't work.

Opinions?

 

[silversx]

i like lettuce.

 

[Rocketman]

I am definately interseted in what you find out on this as i just purchased a t25, manifold and other sundry items and looking to install them in the spring...... keep me posted please i would greatly appreciate it if you do take on this project......

Get me into a turbo sooner!!!! please!

Rick

 

[SERprise In WV]

If you're going to JWT ECU it, then I think that the extra $300 or so for injectors is insurance money well-spent. And, you can up the boost o'plenty.

If you're NOT going to JWT ECU that setup, then you're right: It's a matter of the stock ECU managing the A/F ratio. Which it might do. If it can't do that -STOCK- then ka-boom is probably the answer. Which it might do. It's a tempting experiment, and one I'm profoundly interested in:

I have a T25 setup being shipped to me next week.

I'd L-O-V-E to hear what other, more-experienced-than-I, turbo guys have to say about this kind of setup. It's a great topic.

 

[ProjectSE-R]

Ditto on what Greg said!

 

[Big Boost]

It will work until......

you start hearing a marble rattling sound followed by a KA-BOOM!
I did it when I installed my first T28 turbo. It worked alright. I used an inline fuel pump with the stock injectors and an adjustable fuel pressure regulator. It was definately a band aid and I would honestly not recommend doing it. Go with the JWT set up and you will have piece of mind. I eventually hurt my first motor in late '96 because of detonation under load. Keep your boost to 5psi and it will work. I followed the SE-Rious Sentra Turbo article. Back in 1995, Evan Griffey didn't start off with the JWT system either, but in the next article he went to JWT for the turbo program.

 

[Ben]

I would NEVER do this with a T28. That's too much power for the stock injectors. T25 is a different story though. More discussion in a second...

 

[Ben]

From NismoDriver on the SE-R list:

Ben,
I have a custom turbo kit on my SR20 powered B12 running stock
injectors and stock ECU. I have a big ole honkin turbo on it with an HKS
FMIC and at 5 psi (volumetrically equivalent to around 9 psi on a T25) I made
207 hp to the wheels. However using the wideband oxygen sensor showed that I
was running an Air/Fuel ratio of about 13.5 which is pretty lean. I have
sense remedied the problem with a high pressure/high volume NOS in line fuel
pump and a vortec 10:1 ratio FMU (at 5psi I have about 95 psi of fuel
pressure). with out upping the boost any and adding just the pump and FMU, I
put 232 to the wheels and am no longer running lean, actually a little to
rich in some places in the powerband. I don't want to up the boost anymore
though, because I know I am reaching the threshold of the injectors. I will
soon be installing 50 lb/hr injectors and a Cobra MAF with JWT programming. I
don't publicize it much because of the criticism of the list, I have been
told it can't be done and won't run right..yaddi yaddi yadda, but I drive it
all of the time and it works good enough to be a 13 sec car. Hope this helps.
John



I replied:

> I have a big ole honkin turbo on it with an HKS
> FMIC and at 5 psi (volumetrically equivalent to around 9 psi on a T25) I
> made 207 hp to the wheels.

7psi with no exhaust on the car made me 203hp on the T25. So this level of
airflow is equivalent.

> However using the wideband oxygen sensor showed that I
> was running an Air/Fuel ratio of about 13.5 which is pretty lean. I have
> sense remedied the problem with a high pressure/high volume NOS in line
fuel
> pump and a vortec 10:1 ratio FMU (at 5psi I have about 95 psi of fuel
> pressure)

How much do these other items set you back? How hard are they to install and
calibrate? My whole goal here is to engineer a great bang for the buck
system and if these increase the cost to the level of a JWT ECU and 370cc
injectors, then my goal may not be reached.

These two items- they basically up the flow rate of the injectors above
259cc's correct? This is not something a Walbro replacement fuel pump would
do would it? Are there any other alternatives that would flow just a bit
more fuel?

> I don't publicize it much because of the criticism of the list, I have
been
> told it can't be done and won't run right..yaddi yaddi yadda, but I drive
it
> all of the time and it works good enough to be a 13 sec car.

Hey, if it's been proven in the real world, then that's more than enough for
me. Similar to the guy at the '01 convention that had been using a DET ECU
in his DET powered classic with the DE MAF- been working for him for a long
time.

 

[AZ 2K SE]

I'm glad I'm not the only one thinking of this. I have a 2k Sentra and it really needs a turbo. I have located a good source of T03s and an intercooler worth using. I was thinking with an inline fuel pump or bigger pump and/or FMU and 5-6 psi of boost max, I could pull it off. I'm also looking at an a/f meter to increase engine safety. The ECU and injectors would be stock. I would also re-locate the other o2 sensor behind the second cat for good measure. My car is an auto, a turbo would let me at least break into the 15's. Please let me know what you guys think.

BTW, at 6psi boost you should be ok with the stock injectors. The JWT kit offered way back in Turbo magazine was for the stock injectors. I've seen the same thing since, even at higher levels of boost. I'd stay with 6 psi max to be safe tho.

 

[jburnham]

Anyone Else?

Any more thoughts on this? I'm sure everyone out there who doesn't have the $ to do it right is contemplating this.

Does running lower boost dramatically improve the odds that the stock ECU/Injectors/MAF can handle the A/F ratio?

Does a T25 have a built in BOV [wastegate] and is it easily adjusted down to ~6psi?

 

[Ben]

The T25 has a built in wastegate which is what you are really meaning to say and it's solenoid it automatically set to 6.5-7psi and AFAIK there's not a lot you can do to lower the maximum boost.

I may still try something like this...

 

[g-90]

I'm currently running a t-25 with 50lb injectors/jwt fuel rail/c maf/ 300 tt fp/and front mount IC - at a high of 17lbs of boost

 

[jburnham]

ECU?

I'm currently running a t-25 with 50lb injectors/jwt fuel rail/c maf/ 300 tt fp/and front mount IC - at a high of 17lbs of boost

Not with the stock ECU?

And I suspect your parts have pushed your package way above what us cheap bastards are dreaming of. I would love to see an under $1000 bang-for-the-buck turbo package, even if it only produced 190 whp.

 

[silversx]

I don't know a lot about turbos. Maybe I misunderstood something. Did you say, run a T25 w/ stock injectors and stock ecu? I thought you HAD to have an ECU upgrade to run turbo??

 

[SERprise In WV]

Ben;

I am far from an expert on turbocharging, having just bought my first turbo setup. However, I do know a bit about basic fuel systems and the like.

So, here's the follow-up;

If you add the prices up for a wide-band O2 sensor AND a FMU, you're damn near the cost of a JWT ecu. As in, -right there-.

Is it worth another $100, $200, or even $300 to safeguard your engine as best as is possible, and prevent a dastardly Ppphhht sound, followed by pieces of aluminum that *used* to be valve-this or piston-top-that?

Andreas Mikoleiczik posted in another thread, and I'm paraphrasing, that unless you really, really know what you're doing, a JWT ecu is the way to go.

(Back to my own words)

Stand-alones (and the like, which I consider a rising-rate fpr, FMU, or whatever) are best left to the racers, working on race cars. Not street cars.

Sure, you can over-clock the injectors to add more fuel. But make one mistake in A/F ratio and, as Rob commented, KaBoom is the order of the day.
An extra $550 for the JWT ecu is nothing compared to an engine swap, PLUS the man-hours of your own labor. You *can* learn how to manage the fuel system on your own, but you're probably going to go through an engine or two on the journey.

Answer? Do as you wish. Just realize the gamble you're taking and work within known limits of your equipment. You mentioned my car and how I 'got around' fuel management issues with my direct-port nitrous setup. I didn't 'get around' anything. I know the limits of the stock pump, and have not exceeded that at 78hp of nitrous/fuel. I shoot past the injectors, so the injectors size is not pertinent. Big difference from what you're considering, IMHO.

Tread lightly, my friend...hope this helps. Sorry for the length.

 

[Ben]

If you can dump extra fuel not using the injectors with nitrous, why not with a turbo too?

 

[SERprise In WV]

I shoot past the injectors, so the injectors size is not pertinent.

The key word is 'past'. As long as the fuel pump can supply both the injectors AND the Fogger nozzles, then there's no problem. The injectors only have to shoot as much fuel as they would need NA. The nitrous/fuel is supplied afterwards. I'm manually stuffing it in the cylinder, to be blunt.

With a turbo, you're trying to shoot the supplemental fuel *with* the injectors. And, at varying rpms and under different engine loads. Those variables are changing many times per second.

On the other hand, a direct-port nitrous setup only works under WOT, and between about 3,500rpm and 7,000rpm. It's very controllable, in that somewhat narrow rpm range.

I probably just muddied this up even further. This will all become crystal clear this weekend, when you see my setup and go for a ride. We'll talk.

 

[Ben]

OHHHHH...

Only at WOT is the key there. Didn't realize/remember that nitrous is usually a WOT affair. Gotcha.

 

[Andreas Miko]

I do not think it is a good idea to consider this subject. If you go this route you will end up spending more money than you intended when the motor goes bang. That is anout $600 for a motor and $600 to instale, thats a lot of money spent for stupidity. Do it right the first time and run fast and reliably. You can build a low 13 sec SE-R for less than $2500 in parts. Used Pulsar GTIR turbo, manifold, heatsheilds and Jpipe $900. Used 370cc inj, $250 Starion intercooler $200, JWT ECU $550. Steal intercooler pipes for about $200 and there you go. Total $2,100. This stuff new would go for about $3,000 and you are runing low 13s. Now that worth the money and time.

Andreas Miko.

 

[Big John]

Just to clarify the setup. I paid $50 for a used FMU, $50 for a used NOS HIgh pressure high volume in-line pump. all dyno numbers were made through 2 1/4 exhaust. The wideband O2 was an accessory on the dyno, not a permanent fixure in the car. As was mentioned before this a band aid and not recommended for trying to make big power. I opted to go with the 370cc injectors, JWT ecu w/ 4 bar, Pulsar MAF as recommended by Andreas. I have a lot of parts to install before the car is road worthy. Next dyno will be with 3" exhaust and underdrive pullies as well as the JWT setup. I will dyno again at 5 psi, then 8, then 9 and so forth. I will keep everyone posted on my HP, A/F results.

John
B12 Sentra w/ JDM SR20DE and boost among other things
New Orleans, LA