Go back to previous topic
Forum name4G63 Tech
Topic subjectAny idea why I don't have full boost until 5500 RPMs in 1st gear??
Topic URLhttps://forums.2gnt.com/dcboard.php?az=show_topic&forum=i67&topic_id=9893
9893, Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by FlyinEsi, Aug-06-04 07:07 PM
Hey guys, I have started tweeking the car a little bit again. I have been having problems with the turbo spooling up, but only in first gear. Maybe it is supposed to be this way.

I get on it at low rpms in 1st gear and I don't hit full boost until between 5000-5500. But if I start at low rpms in 2nd-5th, I get full boost by 3300-3700. What gives??

The car pulls like a sum' bitch once boost hits, but it is almost like there is no progressive boost. It almost goes from like 2psi to 18psi in like a 500 rpm band. But every other gear starts at like 2500ish and builds up.

Any ideas?? I'm running DSMlink, finally w/o the SAFC plugged in. I thought maybe that was causing it, but it isn't. Any ideas?

If I can answer any questions to help you guys figure this out, please let me know.
9894, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by eclipzGST, Aug-06-04 08:10 PM
exaust leak? :shrug
What turbo is it?
9895, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by FlyinEsi, Aug-06-04 08:31 PM
Big 16G turbo
Greddy big fmic
ported o2
ported exhaust mani
ported intake mani
550 injectors
lightened flywheel
walbro fuel pump

Can't think of anything else on there that would matter, but if I had an exhaust leak wouldn't that effect every gear? It pulls like a raped ape after 5500 in 1st and every other gear pulls hard a lot earlier.

:shrug
9896, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by eclipzGST, Aug-06-04 08:59 PM
when did it start? Maybe it IS something in DSMLink. :shrug I have no idea dood.
9897, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by FlyinEsi, Aug-07-04 04:35 AM
It did not do it when I was set at 16psi, spooled just fine. But as soon as I raised the psi to 20, couldn't get it tuned and I brought it back down to 18. Been doing it ever since.
9898, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by Hult250R, Aug-07-04 05:44 AM
Originally posted by FlyinEsi
It did not do it when I was set at 16psi, spooled just fine. But as soon as I raised the psi to 20, couldn't get it tuned and I brought it back down to 18. Been doing it ever since.


Turn it back to 16 and see if it still does it. :shrug
9899, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by chrysler kid, Aug-07-04 06:09 AM
my 16g has the same problem, if your 16g is clipped it wont hit hard until about that rpm range because it requires more exhaust gas, but spins faster
9900, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by eclipzGST, Aug-07-04 08:10 AM
Originally posted by chrysler kid
my 16g has the same problem, if your 16g is clipped it wont hit hard until about that rpm range because it requires more exhaust gas, but spins faster


but if that were the case, it'd hit close to the same rpm in every gear.
9901, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by FlyinEsi, Aug-07-04 09:16 AM
Originally posted by eclipzGST
Originally posted by chrysler kid my 16g has the same problem, if your 16g is clipped it wont hit hard until about that rpm range because it requires more exhaust gas, but spins faster
but if that were the case, it'd hit close to the same rpm in every gear.


Not necessarily, correct me if I'm wrong, but it is easier to spool in 2nd-5th because there is much more of a load on the engine. In first gear the car is pulled so easily that the load is not put on the engine as much, and if it is, 1st gear goes by so quickly the turbo doesn't have time to spool. Is this correct, or am I just pulling that out of my ass?
9902, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by 420a-Tnthewerks, Aug-07-04 11:27 AM
is it a gsx? if it is i wouldn't even worry about 1st gear. in a race you would be launching close to that rpm range anyway.
9903, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by eclipzGST, Aug-07-04 02:28 PM
Originally posted by FlyinEsi
Originally posted by eclipzGST
Originally posted by chrysler kid my 16g has the same problem, if your 16g is clipped it wont hit hard until about that rpm range because it requires more exhaust gas, but spins faster
but if that were the case, it'd hit close to the same rpm in every gear.
Not necessarily, correct me if I'm wrong, but it is easier to spool in 2nd-5th because there is much more of a load on the engine. In first gear the car is pulled so easily that the load is not put on the engine as much, and if it is, 1st gear goes by so quickly the turbo doesn't have time to spool. Is this correct, or am I just pulling that out of my ass?


actually, I think it'd be just the opposite. When I had my spiking issue. It only did it in 1st because thats when the turbo spooled the fastest.
9904, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by chrysler kid, Aug-07-04 06:11 PM
not really. because the engine revs so fast it doesnt have enough time to spool. like when you rev the engine and the car is in neutral, boost doesnt build till about 5k and still doesnt really boost fully
9905, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by eclipzGST, Aug-07-04 06:36 PM
Originally posted by chrysler kid
not really. because the engine revs so fast it doesnt have enough time to spool. like when you rev the engine and the car is in neutral, boost doesnt build till about 5k and still doesnt really boost fully

Thats completly different because there's no load.
If that were the case, NOONE would be able to hit full boost in 1st. Shit, anything bigger than a 20G wouldn't see more than a few psi before the 1-2 shift...
9906, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by BigBald, Aug-17-04 09:10 AM
First gear is nothing to worry about...you should be in first a total of 3 seconds...lol.
9907, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by 97gsx, Aug-28-04 06:31 AM
Originally posted by BigBald
First gear is nothing to worry about...you should be in first a total of 3 seconds...lol.


True, but its not all the time you want to launch at 5000. I like my clutch.

I have a GSX with the same turbo and it's running 16psi, i dont think its all the way at 5500 when its in full boost but i know its higher then other gears. You said yours was working fine at 16, but maybe becuase every other gear is when its respooling :shrug I'll pay more attention to mine and get back to you.
9908, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by 97gsx, Sep-10-04 04:18 PM
IF you get too much shaft play side to side you start to rub the compressor wheel... this then makes a smaller comp wheel, thus taking longer to build boost, and sometimes limiting your boost. maybe there is jsut enough to slow if down but not so much limit it once it starts spinnin fast. WHO KNOWS
9909, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by DSMTunerS95, Sep-13-04 03:55 AM
IMO hitting full boost @ the end of 1st gear is pretty common i'm running on a stock 7.8:1 compression 1g and a PTE SCM50 and I don't even hit 24psi in 1st gear, ever, the most i can get is 20 before i have to shift, and it hits 20 right about 6000, 1st gear there is hardly any load on the engine at all, which is why you would see that happening, i find this normal in all turbo cars that are running any turbo worth mentioning. other things could be boost leaks, pre-turbo exhaust leaks, i really dont see a tuning device causing spool up issues. what you should look at is where you hit full boost in 4th gear, if its around 3500 w/16g your fine.
9910, RE: Any idea why I don't have full boost until 5500 RPMs in 1st gear??
Posted by 97gsx, Sep-14-04 06:30 PM
Originally posted by DSMTunerS95
IMO hitting full boost @ the end of 1st gear is pretty common i'm running on a stock 7.8:1 compression 1g and a PTE SCM50 and I don't even hit 24psi in 1st gear, ever, the most i can get is 20 before i have to shift, and it hits 20 right about 6000, 1st gear there is hardly any load on the engine at all, which is why you would see that happening, i find this normal in all turbo cars that are running any turbo worth mentioning. other things could be boost leaks, pre-turbo exhaust leaks, i really dont see a tuning device causing spool up issues. what you should look at is where you hit full boost in 4th gear, if its around 3500 w/16g your fine.


I like that...makes me not worry so much :thumbsup
I generated this page in 0.013954877853394 seconds, executing 7 queries.