Turbo Outta Puff??

4GTuner

Help Support 4GTuner:

Kane_GSR

Kane_GSR

E39A
Joined
Aug 12, 2008
Messages
461
Location
Sydney
Just finished bedding my new clutch in so was doing some spirited driving.

I've noticed when I get to 6500rpm power feels as though it flattens out or drops off.

4G63T with small 16g running 7psi but spiking to 13.8 (eboost peak value - god damn wastegate flapper)

Is that normal as I imagine full hp to be made close to redline and will it be the same with boost nearer the 20psi range?
 
what other mods in your seutup, you might find your old clutch was slipping and you werent feeling the full power of the car and now you are and its more precise you pick up on these things, my small 16g on my fwd started dropping power then too, although i did have a 2.25 inch zorst
 
I think thats about normal isnt it?
Just the characteristics of the Evo Turbo.
moreso that you have the smaller housing, therefore you would be losing a little bit more top end than a big 16g housing would give you.
 
If it's from an evo it's almost certainly a big16g, but anyway.

my vr4 with a big16G makes peak power at 5700 - it's the nature of these engines. Get some big cams and you can have power right the way to 8000rpm, but at the expense of that fat midrange.

Also, if the boost is spiking to 14psi, then dropping back to half that, of course it's going to feel flat at the top end....
 
yer but small 16g is big 16g just not e3 big, you will find if you take comp cover off and measure the wheel it is indeed a big16g
 
I agree with VR-4Squid, if you're runnin stock cams and cam gears its normal for power to drop after 6500rpm.

As for the small and big 16G, i personally havent pulled apart too many, but for those i have, i only found small
16g in vr4-rs turbo, number finishes with 420, and in several evo turbos they all had 68mm exducer comp wheel.

its hard to measure wether its big16 or evo3 big16g coz the diff is only in the size of the inducer on comp wheel.
The inducer on big 16g is 48.056mm and evo3 big16g is 48.336mm which is beez dick in difference.
 
Id say my cars the same i feel it drop off after say 6K to 6.5K. Mines a 16g hybrid and still it drops off.
With the old 14b id say after 5.5K the funs starting to be over. But how responsive are the 14b's!
Prob nothing wrong with your car mate.

Just the nature of responsive turbos they become a restriction and cant flow higher in the rev range.

Other things that might be a restriction you could look at sorting is letting the motor breath, by having a good intake setup and exhaust, including a good dump pipe.

And then yeah cams, coz they sound mad haha:p
 
And attack the exhaust housing with a die grinder. buy a decent sized tungsten tip to start with tho otherwise it'll take ages. Will most likely sort your boost creep, theres a write up on it on the VFAQ site.

A nicce port job will help the wastgate controll the creep
 
if the cams remain standard, the motor wont breathe above 6.5k regardless what you do, playing with intake and exhaust can only help you gain more power up to 6.5k
 
my car when i had the stock 16g turbo flattens out and gets boring after 6000ish as well, and i ran 22psi all the way to redline, i would assuming its because the turbo is just too small to pull all the way to the top
 
milkandoj said:
And attack the exhaust housing with a die grinder. buy a decent sized tungsten tip to start with tho otherwise it'll take ages. Will most likely sort your boost creep, theres a write up on it on the VFAQ site.

A nicce port job will help the wastgate controll the creep
Click to expand...
Exactly guys, its perfectly normal.
good point Milk, have you bored your manifold out Kane?
 
Onr3e said:
my car when i had the stock 16g turbo flattens out and gets boring after 6000ish as well, and i ran 22psi all the way to redline, i would assuming its because the turbo is just too small to pull all the way to the top
Click to expand...

well you would 'assuming' wrong. if it's making the same boost pressure right to the redline, it's not a turbo flow issue (as an example, the stock turbo's on a 6G12 will make 20+ psi down low, but won't even make 14psi near the redline, even with the wastegates wired shut.

With a set of 272 cams the 16g will happily hold 22psi to 8000rpm, and make 240kW or more at the wheels.
 

Latest posts

Back
Top