Just got my first 240SX! - Only makes 5.8 psi boost?

[carbully]

Hey, guys my big day finally arrived today and I got my first 240sx!!! I am so happy.

I joined NICO to do thorough research on what I thought would be the best setup for me and decided on an S14 with SR20DET power due to "out of the box" dependability and reliability (read: don't have to mess with tuning if staying pretty close to stock), potential platform to make a lot of power someday if I want to, and good fuel mileage potential if I stay with stock.

I bought the car at a used car lot already swapped. The motor is completely stock. The swap left a few things to be desired but I can clean them up later on. Things like no fan shroud (I will do the Altima elc fans this spring and loose the W.P. fan), little stuff like that.

The car is a 4-lug non-SE all stock. I really wanted a total sleeper. I felt like only the 5-lug would do until I read about q45 calipers and 4-lug SE-R rotors. I did get a '95 because if I had trouble getting through emissions I think I could make it pass. With a '96 I am sure they would want to scan my ODBII system which would not work with an SR swap.

I willhave pics later this week, I do not pick it up until Wed when they have the A/C installed and the Tach fixed.

Anyhow to my question..., it already has a boost gauge installed. I max out at .4 bar which is 5.8 psi. Everything I have read here tells me that I should get ~7psi with the stock red top. The car has stock exhaust I think, could it be that the stock exhaust is restricting flow to the point that in only makes .4 bar. Or perhaps they have the boost gauge plugged in to the wrong place?

Second question: The tach is pegged all the way against the clock reset button all the time, even with the engine shut off. They have agreed to fix the tach, but is there a common mistake sometimes that can take out the tach during an SR swap?

Thanks!

[Jadesr20det]

my car did the same thing when i went to the local dyno it only hit 5lbs of boost (220hp 200lbs tq). I think it might be the stock old wastegate. As far as your tach issue that is a wiring issue, as i have the same happen to me due to me having the electric fans wired straight to my ignition switch.

[Logan76]

it could be your wastegate actuator arm is bent, or it could be that your boost gauge is off, just some possibilities.

[Hijacker]

220 whp on 5 lbs of boost? No way. Not on a stock turbo.

[Jadesr20det]

220 whp on 5 lbs of boost? No way. Not on a stock turbo.

Theres always one here you go:



sorry technically speaking 219.61 on 5.48 lbs of boost. I would link directly to site but lost the dyno cd they gave me. Can we get back on topic now.

You have officially made me change my sig to "Just because you havent done it, impossible it does not make" Thank you.

[duffman1278]

WHOA!!! wtf?!!??

[redtop91]

Theres always one here you go:

He wasn't doubting your numbers, just your numbers on the stock turbo. Stop freaking out about it. There's more to your engine. You either have an aftermarket turbo or a set of cams. I'd guess you have an aftermarket turbo. His and my point is, you aren't making those numbers on a stock engine so find out what is modified. As regards the 5.8 PSI problem, the wastegate spring is stuck.
Modified by redtop91 at 1:47 PM 11/25/2007

[Jadesr20det]

He wasn't doubting your numbers, just your numbers on the stock turbo. Stop freaking out about it. There's more to your engine. You either have an aftermarket turbo or a set of cams. I'd guess you have an aftermarket turbo. His and my point is, you aren't making those numbers on a stock engine so find out what is modified. As regards the 5.8 PSI problem, the wastegate spring is stuck.

Modified by redtop91 at 1:47 PM 11/25/2007

sorry if i came off as spazzing out. I just get the same hard time whenever I state my #'s. But its all love to me. I understand what you are saying w/the aftermarket turbo however i have a stock turbo (t25) checked the turbo when it came in. Not sure about cams but they didnt look aftermarket and car doesnt idle any different (actually kinda tame compared to some stock SR'S i've been around) when i changed the valve cover gasket. I do however have full 3inch catback, front mount, walboro fp,and thats about it. I just dont understand how some can say that those #'s are not possible with the t25.

[redtop91]

You didn't read what I said. No one is doubting that the T25 can't do that, it just can't do those numbers on less than stock boost. That is where the problem is. I believe your gauge is misreading.

[Jadesr20det]

You didn't read what I said. No one is doubting that the T25 can't do that, it just can't do those numbers on less than stock boost. That is where the problem is. I believe your gauge is misreading.

well then you didnt read what i wrote if thats the case as i posted the dyno chart which means the dyno (thats hooked up to the car mind you, which is why it is able to come up with exact #'s) is wrong. Hmm i think i will go with the dyno that is one of the best in this area for being accurate and actually stingy at times, than doubters (that weren't there) over the internet. Like they say the #'s dont lie, and if anyone else doesnt believe call them up their # is on the sheet or make a trip here and pay for my dyno time and we can do it all over again. Maybe i have a magic motor from DK himself lol but the fact is the motor made the #'s.

Redtop i planned on working under the hood and ill post pics of the turbo next weekend that is there and maybe you can identify it. But my thoughts were that the t25 is stock 80 A/R.

[redtop91]

Edit: NM. But your post still was illegible.

[Eikon]

You say the number don't lie.. but I tend to dissagree.

There is something wrong with your dyno charts. I think the boost readings are incorrect.

According to the chart you made 163whp on 16 lbs. then 165 whp on 0 lbs. then 219 whp on 5 lbs...

Something isn't right with that.

[Jadesr20det]

You say the number don't lie.. but I tend to dissagree.

There is something wrong with your dyno charts. I think the boost readings are incorrect.

According to the chart you made 163whp on 16 lbs. then 165 whp on 0 lbs. then 219 whp on 5 lbs...

Something isn't right with that.

correct something is wrong its called having the boost set too high and car leaning out way too much(look at the a/f ratio). Did it again but again boost was too high so he didnt finish the run (which explains the 0 lbs of boost that and the fact that we didnt unplugged the dyno from the source itself to see what numbers were achieved). Then we unplugged the BC all together and went back to stock setup and acheived the number you SEE before you. #'s dont lie and your lying to yourself if you think that way. Im sure if it were your car you'd feel the same way I do.

[danstachet]

either way, everybody also knows that the person running the dyno can change certain things relating to the settings of the dyno to fudge the numbers. there's 2 dyno places here in my town, both with the same dyno and they both gave me WAY different numbers. at 14psi on a stock turbo with bolt on's, i put 220whp down on one and 245 on the other lol. there's a problem somewhere, that's for sure.

Back the the problem, as everybody else has said, check you vacuum lines for your gauge and your actuator and see if there's anything obviously wrong, if you think its you actuator email me and iv'e got a good stock one laying around. you can have it for the cost of shipping. let me know

[email protected] Dan

[redtop91]

Im sure if it were your car you'd feel the same way I do.

LOL. If it were my car I'd ask for the money I payed for the dyno back.

[Jadesr20det]

[idahotuner]

lol carbully has 69 post lol

[carbully]

lol carbully has 69 post lol

umm your point? You started off with 1300?

Anyhow, thanks, danstachet, that's a very generous offer. They say I will be able to pick the car up on Wed, b ut it will probably be like Friday. I will have a look next weekend.

To test it, I have a vacuum/pressure gauge. I imagine I just feed it 7psi and the arm should pull off at that point, right?

(btw, up to 70 posts now!!! HAHA Nobody can stop me!!!

[redtop91]

69 is a commonly used sexual innuendo. I don't think he was making fun of you because you "only" have 69 posts, but rather 69 is amusing. If you can swap actuators with someone else and see if your boost jumps back up.

[idahotuner]

69 lol. you dont get it, well to bad it is 70 now.

69 was my number al lthrough highschool, every one thought it was funny. lol

[carbully]

Oh, I get it. Sorry I am kind of defensive of my newbie status. No offense.

So, does anybody have a test for wastegate/actuaor? I will search now...

[bgsr240]

I'm pretty sure that the reason all of you guys are only running 6-7lbs. is because you dont have the factory boost selenoid hooked up. My redtop ran 11lbs. from day one...

Buy a boost controller.

[redtop91]

It's not the solenoid people. Stop saying that. It's the restrictor in one of the lines.

[CMG]

It's not the solenoid people. Stop saying that. It's the restrictor in one of the lines.

How can you say that for sure? It's not commonly done because it's not listed in the swap guides. I extended my wires to use the solenoid and voila.

[bgsr240]

How can you say that for sure? It's not commonly done because it's not listed in the swap guides. I extended my wires to use the solenoid and voila.

Finally... thanks man lol.

Wouldn't a blockage in the line to the wastgate cause a massive overboost? Kinda like if you unhooked the wastgate all together? And I have never heard of a single instance of an actuator arm ever being bent, unless it was on purpose by some dumb@ss thinking that he could squeeze more boost out of his turbo that way lol.

[redtop91]

How can you say that for sure? It's not commonly done because it's not listed in the swap guides. I extended my wires to use the solenoid and voila.

You should do some research on how solenoids function and answer that question yourself.

http://www.nissansilvia.com/fo....html

Even though you are wrong that is a discussion for another topic. Not this one.

[Logan76]

if the arm was bent, the wastegate would be open more, causing you to lose boost, not gain it...

[CMG]

You should do some research on how solenoids function and answer that question yourself.

http://www.nissansilvia.com/fo....html

Even though you are wrong that is a discussion for another topic. Not this one.

Have you ever personally had an SR swap with the solenoid hooked up? Me and bgsr240 could be wrong, but we are two people who have first hand experience, which I would rely on far more than any web topic you could point out.

[carbully]

Thanks for the link to that about the restrictor hose. I did not see where it explains how the solenoid works, though, just that by replacing the oem restrictor-hose with an unrestricted hose your boost goes up. I don't even think my 240 has the solenoid installed. I don't recall though I won't have the car until later this week.

So, if I am not using a solenoid at all, could that cause my low boost problem? Did all SR20DET use the solenoid and restrictor/hose to arrive at 7psi?

[Tulsa_S-13]

Have you ever personally had an SR swap with the solenoid hooked up? Me and bgsr240 could be wrong, but we are two people who have first hand experience, which I would rely on far more than any web topic you could point out.

Ryon used an Apex'i AVCR to control boost. I however did use the boost solenoid in my swap, although now I'm running Ryon's old AVCR (Thanks!).

Using the solenoid I was still at 7psi, it wasn't until I stumbled upon this article and replaced the restricted line with a standard vacuum line that I was able to hit 10psi.

http://www.nissansilvia.com/fo....html

I have read a few post were people using the solenoid have seen 10psi, but I'm not sure whether they were using the factory lines or what they had laying around.