Need Boost Sooner

[Riverfurm]

I had my 1.6 Turbo motor for about two month now and like it. It has a Giles Super pump, Pass. 3" down pipe, 3" exhaust and a  Garret T3  turbo running 20 PSI max. When I get 10 psi boost the car really starts to pull all the way up to 20 psi and 5000 rpm. But off the line it still runs like my NA motor. Not much boost in first gear. Second gear boost starts coming in around 3800 to 4000 rpms. Third, fourth, and fifth come in a little sooner 3500. Is this typical. I find myself trying to keep the rpms up so I can stay in the boost zone. Is there a way to get boost sooner? I am happy with the boost control set at 20 psi I had it up to 30 but it did not seem to add much power so I keep it at 20. (Replaced the head gasket after a month, saw some leakage on the outside.  Also installed head studs).  Also mileage is anywhere from 34-39 typical (heavy foot???).

Any Help.....Thanks

[Riverfurm]

A got the smoke factor to a point I can deal with so I will leave the fuel alone. But I guess A smaller turbo is the easiest way to go.

[Vincent Waldon]

K14, baby !!

[blkboostedtruck]

or if you feel ambitious a G60 supercharger will give you boost way sooner!
but a K14 will do it easier like said earlier by Vince
thanks Duane

[hillfolk'r]

slack out the starwheel spring,it really affects the response
so does  turning the eccentric pin
i noticed a definate mileage decrease when i had the smoke screw turned in too far...not a big deal,it afects response  too,but not like the starwheel
here i posted this in another thread a few mins ago

[KTZed]

I have this same slow boost issue with my T3. Dont have a tach yet so cant comment on the rpms but it feels similar to what your describing. It got worse after the intercooler install. My fueling is still stock and im contemplating what the best approach is for faster spool. I want more fuel at low rpms/boost to spool the turbo, but on the other hand I dont want it dumping tons of fuel in while cruising on the hwy at 5psi or so...yes I want my cake and yes I want to eat it  :wink:

ps. my friends '96 Jetta AAZ will make 15psi at 2000rpm in 1st gear :shock:  but the exh housing on the turbo is hardly bigger than the down pipe lol. Smallest turbo ive ever seen.

[spencebm]

the k14 is small but boost comes on very quickly especially with a little additional fuel.  my cheapo intercooler makes it spool slower as well and does not keep efficient boost but i hope that the cooling benefits even it out or i am going back to no cooler.  smaller turbo or bigger turbo?  that is the question.  i get 4 psi cruising at 60 all the time and that is nice, 15 psi max right now.  it isnt too bad

[Riverfurm]

I'll try the starwheel spring adjustment first. But the K14 turbo sounds like the ticket. If it will run 20psi and start to spool up at 2000 rpm that would be great.

Thanks for the help.

[TedV]

does the stock K24 spool up much more fast than the T3?  anyone tried them back to back?

[KTZed]

Ok I did some testing on my car to see what is up. Basically I wanted to see if my boost controller was malfunctioning and causing slow boost.

This is the setup:
1.6TD
T3 Turbo
Small Intercooler
Stock Fueling
Stock downpipe
2.5" Mandrel Exh. no muffler
Boost Controller set to 15psi (everyday for the last couple months)
WG line clamped off (for this test)

Results:
No change. I couldnt get it to boost more than 15lbs even with my foot full on the brake and gas for XXseconds. Boost didnt come on any faster. Is there something wrong with my turbo or are T3's really just way too big? How much will more fuel help? Im hitting 1250F max EGT's. Its killing me waiting for boost...its like watching paint dry.

[Gearhead]

Remember, there are 2 different types of "slow boost."  

The one that most people forget is boost threshold.  Turbos require a certain volume of air passing the turbine before they will even start making boost.  This volume might equate to 2000 or 3000 RPM.  This is determined by the sizing and geometry of the turbo, and it what's normally affected by changing to smaller turbos.  Putting a little more heat to the turbo might help this situation a little bit, but if you are below this threshold you can brake torque it all day and never make boost.  There's just not enough gas going past the turbine to get it up to speed.

The other is lag.  Lag is the amount of time that it takes for the turbo to reach boost speed and pressurize the intake tract.  It is determined primarily by the mass of the turbo internal parts and the mass of air in the intake tract.  Lag is typically witnessed in the higher RPM range when going from steady state cruising to full power.  

Boost threshold is the most annoying issue with turbos, but remember, a turbo that has the proper geometry for efficient high boost condition is typically larger and will not respond until higher RPM on smaller engines.  Of course, if you are running a VNT, you can almost have your cake and eat it too.

[flapjack]

according to my favorite thread you need a 2.5 downpipe

http://www.vwdiesel.net/phpBB/viewtopic.php?t=1352&postdays=0&postorder=asc&start=0

My car is waaaaay faster now Very Happy. On Sunday and Monday I drove an hour to Brett's (DVST8R) shop and the following was done to the formerly stock 1.6TD:

1) Boost pin washer/spacer mod.
2) Electronic boost control. It's currently set at 24 PSI with barely any boost spikes. We ran it at 25 for a while.
3) Fuel injection quantity maxxed out.
4) Fuel governor mod.
5) 2.5" no-cat custom mandrel-bent downpipe to 3" exhaust (starts at bottom of downpipe).
6) EGT probe drilled in pre-turbo.

... and a few more. Big props to Brett for the help. I've had the TD for only a little over a week so I learned a lot during the process.

On Sunday I had leak in the back of the fuel pump where the cold start lever attaches to. We fixed that Monday. Rebuilding the fuel pump is a little easier than it looks.

So far the power is great, a big improvement. A friend of mine commented that it accelerates a bit harder than his MK3 VR6, but different torque curves can play tricks on the mind.

[KTZed]

there are 2 different types of "slow boost."

Very good point Gearhead. I cant count the number of times I have had to argue this. People always complain "OMG I have soooo much lag when I floor it from idle!".....well duh.

I drive over a relatively large hill every week (~1500ft elevation change over ~5km...~3min of full throttle at 110km/h). Even if I drive it in 4th at 110 (dont have a tach but fairly high rpms) I can maybe get it to creep to 17psi.

Im gonna try doing the mandatory boost pin/starwheel/etc. mods and see where that takes me before I go for the downpipe....I dont really feel like changing the turbo or messing around building a DP if i can help it.

[myke_w]

does the stock K24 spool up much more fast than the T3?  anyone tried them back to back?

Also very interested in the answer to this

[andy2]

I ran these turbo's back to back and the k24 spools a bit quicker than the T3.The k24 has a slightly bigger compressor than the T3 and the T3 has a noticably bigger Turbine than the k24.Beacuse the T3 has a bigger turbine it works better for mid range-top end performance and the k24 will provide better low-mid range performance.Both turbos are not efficent when pushed past 21 psi for k24 and 23psi for the T3.