# Some questions, regarding t3t4 setup on a 1.8t



## mccula (May 19, 2007)

First: will a 3" DP into 2.5" exhaust be too restrictive? Reason I ask: I was running 3" DP into stock catback which I believe is 2.25" and was getting alot of lag. Turbo is a t3/t4 50 trim, 63ar.
Second: When should this turbo be spooling? I am currently running a 3" DP into stock cat. Please note that the cat is cut and welded to the DP, making the inlet a higher (3") diameter. The outlet is still the factory size, but I have it running straight off the end of the cat into a turndown, so the factory catback is not hooked up. Could the 6 or so inches of factory exhaust pipe coming off the cat cause a bottleneck enough to affect spool? I am hitting full boost (running 15psi right now) at about 4350 RPM. Again, turbo specs are above.
Third: How long should I let the engine idle before turning it off? I am currently letting it idle 30 seconds, but for the last 1/2 mile to mile before my destination, I try not too boost. Does this sound ok? I though about getting a turbo timer, but if this routine is fine I can totally live with it.
Thanks for any input guys! PS- I did search.


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## Yareka (Mar 5, 2002)

*Re: Some questions, regarding t3t4 setup on a 1.8t (mccula)*

3" to 2.5" will be fine for your setup. I'm assuming you are running low boost since the motor isnt built yet and thats a good move. When you have the motor built and start running 20+, thats when you should move to a full 3" and see some decent gains.
Spool is a tough one to diagnose but that does seem a little slower than a buddies 50 trim. That small piece of stock tubing could be affecting that but there are a lot of other things that could affect spool 
Do you have any exhaust leaks in the manifold? 
What software are you using?
Dont waste your money on a turbo timer, a little self discipline can actually be better than letting your car idle an extra minute after you leave. Stretch that 1/2 mile out to a couple miles and you wont have to let the car idle at all. 
Sounds like you are just starting to enjoy your build, good luck


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## mccula (May 19, 2007)

*Re: Some questions, regarding t3t4 setup on a 1.8t (Yareka)*

thanks for the info! any other opinions or suggestions?


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## 50trim S (Jun 3, 2008)

*Re: Some questions, regarding t3t4 setup on a 1.8t (mccula)*

id say the fact that the you still have the stock cat on there is what is making it spool slow
have you measuredhow big around the factory cat is ? i bet itss less than 2 inches
you need to get rid of it and put a 3 inch test pipe in its place and i bet you would picck up some power and knock your spool to about3800 rpms
my.02


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## x SPY x (Dec 20, 2007)

*Re: Some questions, regarding t3t4 setup on a 1.8t (50trim S)*

A number of years ago I ran a 50 trim on a 1.8t, it spooled significantly faster than what you are experiencing. At the time I had full 3" exhaust, no cat. Take that cat out, replace with test pipe and run a 2.5" catback system, and I'm sure your spool up will get much better.


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## rodney_dubs (Mar 2, 2008)

*Re: Some questions, regarding t3t4 setup on a 1.8t (50trim S)*


_Quote, originally posted by *50trim S* »_id say the fact that the you still have the stock cat on there is what is making it spool slow
have you measuredhow big around the factory cat is ? i bet itss less than 2 inches
you need to get rid of it and put a 3 inch test pipe in its place and i bet you would picck up some power and knock your spool to about3800 rpms
my.02


Funny... Bob stuck a factory cat into his engine a few years ago on the engine dyno and lost basically no power, no change in spool, @ ~500bhp. 
The factory cat is not the problem. 
What are you using for boost control?
Also, what turbine wheel do you have?


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## split71 (Aug 26, 2006)

*Re: Some questions, regarding t3t4 setup on a 1.8t (rodney_dubs)*

I would say the spool sounds a bit off for 15 PSI. I run the 50 trim but the .48 a/r version. I hit full boost @ 4000 rpms and that's 22 psi...i'd definetly consider a 3" exhaust for sure.


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## mccula (May 19, 2007)

*Re: Some questions, regarding t3t4 setup on a 1.8t (rodney_dubs)*


_Quote, originally posted by *rodney_dubs* »_

Funny... Bob stuck a factory cat into his engine a few years ago on the engine dyno and lost basically no power, no change in spool, @ ~500bhp. 
The factory cat is not the problem. 
What are you using for boost control?
Also, what turbine wheel do you have? 

I know the factory cat isn't a restrictive point, one of the few things vw's done right







However, the rest of the factory piping coming off the back of the cat might be causing a bottleneck.
I am using a manual boost controller, not sure what turbine wheel. It's the t3t4 50 trim, 63 ar that comes with the kinetic 1.8t hw kit.
I am only on unitronics stg. 1+ software and stock fueling, I guess that might be a cause too.


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## Noobercorn (Aug 17, 2007)

*Re: Some questions, regarding t3t4 setup on a 1.8t (mccula)*

how does it spool with NO mbc? i would eliminate that, and focus on spool at WG boost before introducing another variable.


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## mccula (May 19, 2007)

*Re: Some questions, regarding t3t4 setup on a 1.8t (Noobercorn)*


_Quote, originally posted by *Noobercorn* »_how does it spool with NO mbc? i would eliminate that, and focus on spool at WG boost before introducing another variable. 

that spool above in the first post was just the WG, which only boosts (correctly) to 11.6 PSI (.8 bar spring in tial wg)
it didn't really change w/ MBC


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## Noobercorn (Aug 17, 2007)

*Re: Some questions, regarding t3t4 setup on a 1.8t (mccula)*

gotcha. 
have you swapped in a different hot side just to toy around? have you dynoed at all graphing boost? 
any leaks? 
the exhaust is prolly fine if i had to guess.


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## SkootySkoo (Aug 8, 2004)

*Re: Some questions, regarding t3t4 setup on a 1.8t (Noobercorn)*

I have my 50 trim set to about 20psi, and I see full boost around 4200 depending on the gear. Second gear I get full boost probably around 4350. You gotta remember you went with a larger hotside. This turbo in my eyes shines in the upper rpms. Don't worry about when it spools just get on it to 7k+ and you'll forget all about when it spooled because you'll be too busy trying to hold onto the wheel.
This is with a full 3 inch back exhaust and a 3 inch to 2.5 inch intake. The turbo itself is exactly like yours t3/t4 50 trim with a .63 hotside. With this setup I hit 306whp on about 18psi and it was leaning out in the high rpms due to a bad maf. 
I let my car idle for about 1-2 minutes after hard driving just to be on the safe side. Don't waste your money on a turbo timer when your butt is free. Put that extra 100 dollars somewhere else. But that's just my opinion.
Edit: just noticed you said your still on stock injectors and uni 1+. If I were you I'd change that asap. Get some 630s and a 3bar or 580s and a 3.5 and upgrade to unis 630 file. After you spend on that start saving for a new cutch because in a few months you may not have a clutch anymore.

Good luck with it and enjoy. 




_Modified by SkootySkoo at 1:20 AM 10-29-2008_


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## Yareka (Mar 5, 2002)

*Re: Some questions, regarding t3t4 setup on a 1.8t (Noobercorn)*

With a 50trim, we can assume you are running external wastegate. Are you sure its not opening slightly before it should? I'd take the wastegate line off and do a CAREFUL pull up to 15psi just to see if that gets you anything. 
The problem with running the somewhat open exhaust that you are, is that its very difficult to track down exhaust leaks that really could be hurting you. Anything pre turbo could be hurting spool, and if its before the first o2 sensor the ecu probably isnt getting a good reading.
People have done big turbos on ko3 software but I'm not a fan of it at all. The timing curve of a bt car and a ko3 dont match up very well. BT software drops timing in the low end to increase spool.


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## mccula (May 19, 2007)

*Re: Some questions, regarding t3t4 setup on a 1.8t (Yareka)*

could a leak at the wastegate flange cause this???
also, my vac is reading about 10-12 mmHG, but when you come out of boost, it goes down as low as 23-24mmHG... vaccum leak? because of leak at wastegate flange of exhaust mani.?


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## Yareka (Mar 5, 2002)

*Re: Some questions, regarding t3t4 setup on a 1.8t (mccula)*

You should be pulling 18-20" on a good vacuum system, so yeah you definitely have something going on there. 
Pickup a can of seafoam(search for how to use this properly) and you'll find your exhaust leaks with a quickness. To find your vacuum/boost leaks you need to build or buy one of these.
http://www.siliconeintakes.com...7d5b1


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## mccula (May 19, 2007)

*Re: Some questions, regarding t3t4 setup on a 1.8t (Yareka)*

i definatley have a vacuum leak somewhere. i have no idea where though... engne idle is horrible, it bounces down, than back up, and stalls out sometimes when in neutral.
this is the biggest PITA, i thought it was at the wastegate, because on of the bolts holding it to the exhaust mani was a little too long, so i spaced it (the bolt) with a nut, and tightened it so it's really tight now. now the idle is worse, i don't know how to find this leak


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## Yareka (Mar 5, 2002)

*Re: Some questions, regarding t3t4 setup on a 1.8t (mccula)*

Dont get frustrated man, its all part of the learning process. 
Learn your way through it so you can teach someone else later








Its sounds like you are having misfires at idle which come from plugs/coils or having massive vacuum leaks.
You need to build or buy that leak tester from that link above, that is the only way to really get rid of ALL of the vacuum leaks. I'm sure you've checked the obvious ones, but if you still have your stock pcv system then you are probably having issues there.
Use your vagcom or find someone local who has one, so you can check your fuel trims. At low boost you can probably get by with being slightly lean, but you can do damage by going wot before fixing the issues. You need to clear codes/fuel trims anytime you fix a leak. That forces the car to readapt so you can see the changes you are making.


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## not SoQuick (Jan 8, 2004)

*Re: Some questions, regarding t3t4 setup on a 1.8t (Yareka)*


_Quote, originally posted by *Yareka* »_Dont get frustrated man, its all part of the learning process. 
Learn your way through it so you can teach someone else later








Its sounds like you are having misfires at idle which come from plugs/coils or having massive vacuum leaks.
You need to build or buy that leak tester from that link above, that is the only way to really get rid of ALL of the vacuum leaks. I'm sure you've checked the obvious ones, but if you still have your stock pcv system then you are probably having issues there.
Use your vagcom or find someone local who has one, so you can check your fuel trims. At low boost you can probably get by with being slightly lean, but you can do damage by going wot before fixing the issues. You need to clear codes/fuel trims anytime you fix a leak. That forces the car to readapt so you can see the changes you are making. 

http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif damn good advice


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## mccula (May 19, 2007)

*Re: Some questions, regarding t3t4 setup on a 1.8t (not SoQuick)*

ok so I made the boost leak tester and found a few. We fixed them but even after fixing them, it didn't change vacuum at all. At best, the car will pull 15 inHG of vac. It still idles rough to the point where it will die sometimes if not in gear. Doing throttle body allignments and resetting ecu seems to help, albeit only a bit. 
Anyone have any ideas before I take this to a shop and spend the money I was gonna spend on fueling and s/w on this leak?


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## not SoQuick (Jan 8, 2004)

*Re: Some questions, regarding t3t4 setup on a 1.8t (mccula)*

the money should be spent on vag com 1st before heading to a shop or for fueling








did you ever pull the fuel trims? btw it takes some part throttle and driving time for these to adapt after resetting.iirc its block 31 or 32 
also did you ever get anywhere with the exhaust leak or if there was one?pre turbo will cause strange things


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## mccula (May 19, 2007)

*Re: Some questions, regarding t3t4 setup on a 1.8t (not SoQuick)*

vag com'd it, nothing really special came up. 
Talked to USRT... they think me boosting it w/o software might have caused the piston rings to go due to running lean... would piston rings cause vac loss???


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## Noobercorn (Aug 17, 2007)

*Re: Some questions, regarding t3t4 setup on a 1.8t (mccula)*


_Quote, originally posted by *mccula* »_would piston rings cause vac loss???

yep. if the combustion chamber has leaks, it cannot SUCK. imagine a vacuum cleaner's hose if it was littered with holes.


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## mccula (May 19, 2007)

*FV-QR*

Did compression test:
First round:
cyl 1: 165
cyl 2:163
cyl 3:165
cyl 4:166
Repeated test to ensure results, got the following w/o changing anything:
cyl 1: 170
cyl 2: 168
cyl 3: 167
cyl 4: 166.5
Checked coolant temp through VAG COM after I was all done, after waiting about 10-15 mins and it was at 50*C, so it's safe to say engine was warm enough. Did test w/ fuel fuse pulled and engine cranked at WOT. Cranked around 5 times each, more just till the gauge stopped going up.
Doesn't look like there is any trouble there, thank god...
The only code I am getting In VAG COM is 02 sensor. It's not reading right, also, engine load seems a little too high at times according to vag (at idle.) also ran throttle body alignments on multiple occasions.
After clearing codes and TBA, car does run OK for a while, but still only gets 15 inHG of vac.


_Modified by mccula at 10:48 PM 11-6-2008_


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## mccula (May 19, 2007)

*Re: FV-QR (mccula)*

anybody have any opinion on those compression test results?


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## Yareka (Mar 5, 2002)

*Re: FV-QR (mccula)*

Compression looks ok because it is consistent througout the cylinders, thats most important.
Couple things, you definitely need a fresh o2 sensor in there if you are getting codes for B1S1, thats the primary o2 sensor thats very important to have good readings.
Also, you should be seeing ~80*c after idling for that long, so you need a new coolant top sensor.


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## Agtronic (May 14, 2001)

*Re: Some questions, regarding t3t4 setup on a 1.8t (mccula)*

Your spool time seems perfectly normal for a 50 trim with a .63 housing. Those who say theirs spool at 4000 are probably running the .48 a/r housing. I have the same turbo, and I hit full boost (15 psi) @ ~4500 ... This is an old dyno sheet, check out the green line (boost) :


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