Notices
Forced Induction Turbochargers and Superchargers..Got Boost?

1st Gear Boost

Thread Tools
 
Search this Thread
 
Old Sep 20, 2012 | 03:47 AM
  #1  
Drock's Avatar
Drock
Thread Starter
Registered User
 
Joined: Apr 2007
Posts: 122
Likes: 0
From: Montreal
Default 1st Gear Boost

hi.... i'll list my setup here again..

2005 non-rev, 6MT
Vortech V2, 3.12pulley
600cc DW injectors
walbro pump
Uprev GT MAF
tuned with Uprev
new plugs
autometer boost gauge
Innovate AFR
MD plemum spacer
Berk HFC
Ichiba Y-pipe
Tanabe exhaust

418whp and 349wtq on Dynapack Dyno. approx 8lbs


was just curious.. if im supposed to see full boost under full power in first gear..?

with the 3.12 car is making about 8lbs..
I see the 8lbs of boost, under full throttle no problem in 2nd, 3rd and 4th..

but I cant seem to get full boost in 1st..? im hitting maybe 5-6lbs..?
and I really have to smash the pedal.. to get up there lol..
as you know 1st is very short.. so it reaches redline fast.. and have to change gears..right away

is this normal for 1st gear.. that boost just doesnt have enough time to built up.. my assumption with a SC.. shouldnt make a difference etc..

not sure if its belt slip.. cause it doesnt seem to happen in the other gears..

so im wondering if this is normal for 1st gear.. or if in the end..its just belt slip..?
Reply
Old Sep 20, 2012 | 06:25 AM
  #2  
TopgunZ's Avatar
TopgunZ
Registered User
 
Joined: Nov 2011
Posts: 296
Likes: 0
From: Denver
Default

I kind of wish i didnt hit full boost in 1st...lol.. Allows you to hook up easier.

Reply
Old Sep 20, 2012 | 06:38 AM
  #3  
Drock's Avatar
Drock
Thread Starter
Registered User
 
Joined: Apr 2007
Posts: 122
Likes: 0
From: Montreal
Default

hi...
ok but you are running turbo right..?

the car makes boost in 1st no question.. probably reaches around 5-6lbs...before having to change gears..

it just seems it doesnt make full boost in 1st.. as it does in 2nd,3rd,4th etc..

so im just curious if this is normal for a SC setup... that since 1st gear is so short that it doesnt make the same boost as in 2nd,3rd, 4th.. which reaches about 8lbs undr FT..
Reply
Old Sep 20, 2012 | 07:05 AM
  #4  
str8dum1's Avatar
str8dum1
New Member
iTrader: (11)
 
Joined: Oct 2007
Posts: 8,807
Likes: 7
From: raleigh-wood NC
Default

you still need to fill the volume of the charge pipes. between that lag and the short time that you are in 1st, its no surprise you dont hit full boost
Reply
Old Sep 20, 2012 | 07:37 AM
  #5  
ranmas2004's Avatar
ranmas2004
Registered User
 
Joined: Sep 2011
Posts: 69
Likes: 0
From: Allentown, PA
Default

Originally Posted by str8dum1
you still need to fill the volume of the charge pipes. between that lag and the short time that you are in 1st, its no surprise you dont hit full boost
Happens to me too. I have a turbo and dont even get a chance to get barely 1 psi in 1st. Its a good thing because you have traction.
Reply
Old Sep 20, 2012 | 07:42 AM
  #6  
djamps's Avatar
djamps
Registered User
iTrader: (1)
 
Joined: Dec 2008
Posts: 4,492
Likes: 10
From: MD
Default

The TB doesn't open fully in 1st gear even with the uprev throttle map. Not sure if it's 'enough' to limit boost, just throwing it out there. You also need to remember the engine is under much less load in 1st gear which at least with turbos, might not be enough to build the boost up.
Reply
Old Sep 20, 2012 | 08:27 AM
  #7  
TopgunZ's Avatar
TopgunZ
Registered User
 
Joined: Nov 2011
Posts: 296
Likes: 0
From: Denver
Default

A positive displacement will hit peak in first, but thats a whole different story.
Reply
Old Sep 23, 2012 | 09:21 AM
  #8  
nathanwl2004's Avatar
nathanwl2004
New Member
iTrader: (2)
 
Joined: Jul 2005
Posts: 738
Likes: 0
From: charlotte ,nc
Default

Originally Posted by TopgunZ
I kind of wish i didnt hit full boost in 1st...lol.. Allows you to hook up easier.

look up the e-boost2 boost controller. it can be tuned to limit boost for each individual gear. IE 5 psi in first, 7 in second, 14 in third and so on.

Last edited by nathanwl2004; Sep 23, 2012 at 09:24 AM.
Reply
Old Sep 23, 2012 | 03:20 PM
  #9  
binder's Avatar
binder
New Member
iTrader: (8)
 
Joined: Jan 2007
Posts: 6,457
Likes: 7
From: terre haute, IN; STL, MO
Default

technically the SC is tied into rpm of the engine so it shouldn't make a difference but with the very short amount of time in first gear there is going to be a lag between building of pressure and display on the boost gauge. So it's not "lag" as in a turbo system but it's just system lag to display the pressure. It also could be some belt slip since the crank will accelerate at a higher rate in lower gears thus causing a higher chance of the crank pulley moving faster than the belt can hold on to for a short period.

turbo system is completely different for all those that answered based on turbo results. Turbo's build spool based on engine load. Lower gears have less load therefore it will produce less boost in lower gears.
Reply
Old Sep 23, 2012 | 04:24 PM
  #10  
unvmyg35's Avatar
unvmyg35
Registered User
iTrader: (15)
 
Joined: Sep 2011
Posts: 467
Likes: 1
From: San Mateo County
Default

I agree with binder. I see about 7psi showing on my gauge when im about 6600rpm in 1st gear. I see full boost in all other gears of 11psi.
Reply
Old Sep 24, 2012 | 06:44 AM
  #11  
UMW350Z's Avatar
UMW350Z
Registered User
iTrader: (18)
 
Joined: Apr 2006
Posts: 2,148
Likes: 0
From: Piscataway, NJ
Default

I'm usually through the gear so fast after the boost hits, I don't look at the peak. Are you hooking up?
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Colombo
Forced Induction
35
Nov 9, 2020 10:27 AM
sherm
Engine & Drivetrain
15
Apr 11, 2020 05:21 PM
Conway_160
Drag
3
Sep 29, 2015 08:07 AM




All times are GMT -8. The time now is 12:06 PM.