20g Qestion

[prophecy7115]

Ok i am going to make it quick, i go to school and i work so i need my car and cant have another 1 day without it, so my friends came along and gave me a good price on a 20g with everything i need to install it ($250.00). It is the hahn super 20g, but i have stock fuel and wont have money untill 2 weeks from now, and the lowest i can run that turbo is at 15psi, will that 15 psi ruin my car? I do have other things

(LOOKING FOR AN UPGRADED TURBO AS WELL, I GUESS THIS WOULD HELP WITH FUEL IF I HAD IT BUT FOR NOW THIS IS ALL I HAVE)
~shep tranny
~6puck clutch & fidanza flywheel
~injen filter
~HKS SSQ
~2.5 turbo back
~ngk plugs & taylor wires.

No fuel but i need my car running, will i screw anything up by running (min) 15psi on that turbo?

 

[timloomis]

you should be ok on that psi,but your car will be slow as hell since its a big turbo and is meant for 20+ psi.

 

[gsx951]

15psi on a 20G is much more flow than on a smaller turbo but you'll stay out of the gas until you get a fuel pump and injectors. Show some restraint until you can upgrade and you'll be fine

 

[prophecy7115]

,but your car will be slow as hell since its a big turbo and is meant for 20+ psi.

OK how is this please explain why i would be really slow. Yes my car will be laggy but not slow as hell, the whole meaning of this post is for me to find out if i can cause damage to my motor with 15psi of a turbo that flows around 48-49 lbs/min, because i dont think i will have sufficient fuel for so much air. Which means i am pushing my car further than a 16g on 15psi or a t-25 or a 14b. Now please give me detail on why i would be slow as hell?

so i am going to be slow because to much air for my fuel system to account for
what is tuners coming to. I mean do you understand what i am trying to say? I compliment your answer but please dont take a guess on a question that may cause me my motor.

As i was, please anybody that has any information on this topic please help out, thank you.

 

[doug]

Fuel cut will become a close acquaintance. You'll start hitting fuel cut before you blow your engine since you have no fuel control.

 

[oldman]

Simple, un-hook the actuator arm and drive it like a N/A until your fuel system upgrade or have access to a logger.

 

[prophecy7115]

OK i spoke to a knowledgeable dsmer, and it was said that nothing should really happen at 15, if he ran his evo 16g at 17psi all day with stock fuel system without any problem, and this 15psi shouldn't have an effect on anything but the intercooler after a while. If so please comment on this.

 

[94Jettameowpsst]

Rely on what your car says when you throw 15psi to it on stock fuel. Get a logger first atleast :-/ I see a fried ring in the making

 

[doug]

A 20G at 15 PSI will flow more than an Evo16G at 15 PSI. You still will probably hit fuel cut, but you never know. Several of the Miami guys have loggers-- borrow one.

 

[prophecy7115]

and once i get a logger what to look for? what is it that i look at? 02v right? Also fried ring? how is that possible? leaning out?

 

[40oz]

15 psi is 15 psi is 15 psi in your manifold. The turbo doesn't make a difference. That said, I don't see how you can only run a minimum of 15 psi. When I drive my car like a sane person, I try not to see any boost. Gas costs too much. Just wait until you have the money and feel safe about your fuel system before you go boosting all over the place.

 

[prophecy7115]

15 psi is 15 psi is 15 psi in your manifold. The turbo doesn't make a difference. That said, I don't see how you can only run a minimum of 15 psi. When I drive my car like a sane person, I try not to see any boost. Gas costs too much. Just wait until you have the money and feel safe about your fuel system before you go boosting all over the place.

Once again blindfolded answers.
I have no turbo in my car, i have responsibilities, i go to university 40 miles away, i work i take care of all my brothers, i need this car and i didn't want to throw on the stock turbo, so i tried looking for an upgraded one, But they all would flake right before the deal. So my friend sold me a 20g for 250 with everything i need, so i am putting it on but i am scared, cause i want to feel what it could do! but i don't want to hurt my motor, but the wasgate min psi is set to 15 all the way to 30psi. Understand? I just hope i don't break anything, i am scared!!!!.

Oh and 15psi is not the same on all turbo's. Ask my peeps on tuners

 

[doug]

and once i get a logger what to look for?

Timing retard will tell you if you're getting knock from running too lean or whatever, so that's a key one. O2 voltage is OK, but not precise enough to be of a lot of value in this case. I'm no pocketlogger expert since I have DSMLink, so I'll step aside and let someone that's used a logger take over.

 

[40oz]

Look, I'm trying to help you. Put the turbo on, get a boost gauge. When you're driving, there's something called the throttle. It's controlled by the pedal on the far right. If you don't depress this pedal all the way to the floor, it's easy to control turbo spool. You can have a turbo on the car with no wastegate and still not make any boost. In fact, with a turbo with a larger-than-stock exhaust housing, you can even use more throttle because it takes more exhaust to spool the turbo.

Also, like oldman said, you can disconnect the wastegate flapper from the arm and make pretty much no boost with any throttle you want.

In layman's terms, put the turbo on the car and don't drive like you're trying to win a race. Everything will be fine.

I'll just ignore the 15 psi on different turbos thing for now, since it doesn't really pertain to the solutions.

 

[Waredtalontsi]

15 psi is 15 psi is 15 psi in your manifold. The turbo doesn't make a difference. That said, I don't see how you can only run a minimum of 15 psi. When I drive my car like a sane person, I try not to see any boost. Gas costs too much. Just wait until you have the money and feel safe about your fuel system before you go boosting all over the place.

Not true, quit giving missinformation!!!
14b @ 15psi = 405 cfm
S16G @ 15psi= 505 cfm
B16G @ 15psi = 550 cfm
should i keep going, or can you see that the bigger the turbo the more air its moving!!

 

[40oz]

Not true, quit giving missinformation!!!
14b @ 15psi = 405 cfm
S16G @ 15psi= 505 cfm
B16G @ 15psi = 550 cfm
should i keep going, or can you see that the bigger the turbo the more air its moving!!

I wouldn't even bother except I take offense to someone accusing me of "giving missinformation."

14b @ 15psi != 405 cfm.

14b compressor map
Courtesy of http://www.stealth316.com/2-3s-compflowmaps.htm#fm, rehosted at tinypic.com

The x-axis is the air flow rate. It's not in CFM, but that's not important. The y-axis is the pressure ratio. On Earth, at sea-level, a 2.0 pressure ratio is 14.7 or so psi, so around 15 psi. See how for any given pressure ratio there are multiple flow rates possible? The most efficient flow for a 14b at 15 psi is around 297 cfm. The bleeding edge maximum is around 420 cfm, which is why you found some figure that says 14b @ 15 psi equals 405 cfm, even though that doesn't truly make any sense. As you look at maps for larger compressors, you'll see that the efficiency is different and the max flow for any given pressure ratio increases. That doesn't mean that you're actually getting more flow, you're just using the turbo in a different area of its efficiency.

Should I keep going or can you see now that you shouldn't accuse me of "giving missinformation."

 

[prophecy7115]

. It's controlled by the pedal on the far right. If you don't depress this pedal all the way to the floor, it's easy to control turbo spool. .

Good explanation but how do you depress the pedal all the way to the floor? .
Its OK dsm's have a way of doing things, But hey thanks for the help no joke i appreciate the comment but somethings add and other don't.

For example if your theory is true, lets solve it.
I will race you in your 14b at 15 pounds and i will have a 20g at 15pounds, and lets see who wins? Then you can race my friend on a evo3 16g at 15 psi. You really expect all the races to be a tie? (all cars stock fuel)

Also if 15 psi is 15psi then why could i run 15psi on all turbos with stock fuel, but once i get bigger than a 18g i have to watch out? answer these questions and i will respect your opinion on turbo theory. But till then i would like to hear some response on my little problem. IS IT SAFE FOR ME at 15psi on 1 WOT run to See what its like?

 

[94Jettameowpsst]

You should clue me in on this one?!? I understand what you're sayin 40 but that flow rate increases as the rps go up (more air needed for combustion). Im not understanding what you're saying. Im pretty new to compressor maps, so im not gonna sit here and try to argue this one, but 15psi on a 14b say makes 220whp, that same 15psi on a gt40r lets say on my friends civic, made 402whp. Seems like that makes sense WTF

 

[40oz]

If everything other than the turbo was stock on all the cars, all three turbos held 15 psi steadily to our shift points, and we launched and shifted exactly the same, then yes, I would expect the race to be very close. Power/spool differences would result from the different turbine sides and the difference in intake temperature based on whose compressor was most efficient through the race.

If you put a big enough compressor on a small enough engine, it won't even spool to get to 15 psi, how do you explain that?

As far as your question, which is what this is supposed to be about anyway, I would be weary of going WOT at 15 psi on pump gas without a fuel pump. Mostly because you have a larger exhaust. Maybe you could find someone local with a wideband to watch as you make a run? If it gets lean, shut down. Or, you could pay a little bit more to put it on a dyno and watch the AFR. Keep it mind that it will run leaner on the street, though.

Or, you could just try it and see if your engine blows up. That's probably what I would do.

Can you at least re-wire the fuel pump?

 

[40oz]

You should clue me in on this one?!? I understand what you're sayin 40 but that flow rate increases as the rps go up (more air needed for combustion). Im not understanding what you're saying. Im pretty new to compressor maps, so im not gonna sit here and try to argue this one, but 15psi on a 14b say makes 220whp, that same 15psi on a gt40r lets say on my friends civic, made 402whp. Seems like that makes sense WTF

15 psi on a GT40R according to this compressor map is about 283 CFM at a minimum. Any less flow than that and the compressor will surge/not spool. 296 CFM is the sweet spot (highest efficiency) for a 14b at 15 psi. Basically, that means that the 14b is perfectly sized for an engine that uses 296 CFM at 15 psi manifold pressure, which is probably pretty close to a stock 4G63. That's a bit of an over-simplification, but it's close enough. Back to the GT40R. It's terribly sized for a stock 4G63. It's pretty good for a 4G63 with a huge exhaust, excellent exhaust manifold, perfectly ported head, oversized valves, crazy cams, excellent intake manifold, bad-ass intercooler, and probably some nitrous. Judging from the compressor map, the GT40R is most efficient at ~605 CFM at 15 psi. So basically, the Civic engine in this case flows a lot better than the stock 4G63. Put a 14b on the Civic engine and things would get pretty ugly.

To summarize, GT40R on stock 4G63 at 15 psi... not really gonna work. 14b on modded Civic at 15 psi, not gonna work either.

And of course, it's never that simple, there's the whole other side of the turbo that makes things even more interesting.

That's why it's best to leave this sort of thing to people like Forced Performance. Or any turbo shop who has tons of experience with turbos on a specific platform. I hate turbos now. Thanks guys.

 

[prophecy7115]

Hmm i soppose i could re-wire my fuel pump. I still need injectors, now i am not saying i am never going to get them but not for another 2 weeks.

 

[timloomis]

that what i meant by slow,your gonna be waiting for that thing to spool.

 

[jaredgsx]

prophecy you are acting like a woman. calm down..You seem to want it both ways, you want to be able to run the car, that you dont know will be able to handle what you have done to it, but then you get scared saying that you dont want to blow up your eninge. Here is some good advice, dont be mean to the people who are trying to help you. They answered your questions manytimes, i just dont understand why you did not see it?

1. If you dont know if it will do ok with the stock fuel system, disconnet the arm from the wastegate.
2. Just dont get on the gas, untill you CAN afford to risk the car, or even better, just wait till you have get a few hundread for a pump and some injectors.
3. 40 is right. Totally right.

 

[-red97rum-]

15 psi is 15 psi is 15 psi in your manifold. The turbo doesn't make a difference. That said, I don't see how you can only run a minimum of 15 psi. When I drive my car like a sane person, I try not to see any boost. Gas costs too much. Just wait until you have the money and feel safe about your fuel system before you go boosting all over the place.

Ha! Good stuff

Quit misinforming people, please.

 

[crankbender]

Ha! Good stuff

Quit misinforming people, please.

Actually he is much much closer than you think.

Other than the change in intake charge temp and volumetric efficiency (on the hot side) 15 psi is 15 psi in the manifold. This is of course assuming everything is equal.

Somebody post up a link to the old threads about this....the one with the discussions on VE and all that jazz. I will do it when i get off work if noone else finds them.

(Hint I wrote a good portion of the thread)

You need to read the entire thing all the way through to understand what 40 is saying.