shimming the stock wastegate and other cheap/free performance mods.

[gixxer750]

just bite the bullet and buy an EBC. You can run stock boost for reliablity day in and day out, and have power at the push of a button

 

[lagged]

just bite the bullet and buy an EBC. You can run stock boost for reliablity day in and day out, and have power at the push of a button

best option! :icon_bigg

 

[suprafredde]

Well when I installed the Saab APC (their own standalone EBC) I HAD to shim the actuator just to hold higher boost pressure. Before the shim I could not go past 0.7 bar, the exhaust pressure pushed the wastegate open and I could not build more boost. Even though I have LR elbow and 3" all the way.

The performance increase with the EBC is... well you have to try on your own. No linear wastegate opening here, poff-full boost

suprafredde

 

[albertmdh]

i shimmed 4 washers on each bolt the other day, works like a dream, pegs the stock boost gauge, major improvement.

 

[profuse007]

fuel cut defense

FCD??? sorry, im new to this term, what does it stand for and what does it mean?

 

[Idealsupra]

running the wastegate actuator line to the intake manifold (what you were suggesting?) seems to me to be a MUCH better solution than poking a small hole in the line.

to me, damaging a part for "performance" is not an option to replace a real modification (even if thats shimming the wastegate)

i 100% AGREE with you man..that was my point...ghettoness is stupid...i was just saying it WOULD work...not that i suggest doing it

 

[lagged]

i 100% AGREE with you man..that was my point...ghettoness is stupid...i was just saying it WOULD work...not that i suggest doing it

cool.

btw i love the pic of your car you are using for your sig.

 

[Idealsupra]

cool.

btw i love the pic of your car you are using for your sig.

thanks man...i like it too heres a bigger version:

 

[MisterTurbineTwister]

I actually used my Mityvac and performed a pressure test with different thicknesses of shims. I used the pressure side of my MityVac and attached it to the wastegate actuator. I also used my pressure/vacuum gauge tool in between the wastegate actuator and the MityVac tool to read pressure.

I applied PSI to the wastegate actuator until I saw the TSRM recommended amount of movement in the linkage and recorded the PSI readout on the gauge. I performed this test with approximately 3mm increments of increased shim thickness (approximately the thickness of 1 washer) and these numbers are the mm @ PSI when the wastegate was opened. Basically performing a TSRM wastegate actuator test at different shimming levels.

Here are the numbers that I recorded from a stock CT26 bench test:

-Stock (no shims): Wastegate begins opening @ 7.4-7.5 PSI
-3mm shim (1 washer thick): Wastegate begins opening @ 7.7 PSI
-6mm shim (2 washers thick): Wastegate begins opening @ 8.2 PSI
-9-10mm shim (3 washers thick): Wastegate begins opening @ 8.8 PSI
-12mm shim (4 washers thick): Wastegate begins opening @ 9.6 PSI
-14-15mm shim (5 washers thick): Wastegate begins opening @10.7 PSI

As you can see, with more shim thickness, the PSI steps become steeper.
This is due to the increased curve in spring tension holding the wastegate actuator in the shut position.

I stopped testing at this point because the TSRM (toyota supra repair manual) factory recommended test says that you should never apply more than 11.4 PSI to the wastegate actuator for testing to prevent damaging the actuator. This is of course with no shimming at stock level, but I decided not to push it's limits.

I would imagine that the wastegate actuation PSI levels would be close to that of the boost limitations.

If you have replaced your stock head gasket with a stock replacement, you can safely run about 9.5-10 PSI. With the stock gasket still in place, I would not run any more than 8.5 PSI MAX. IMO, I wouldn't run any more than 8.0 PSI personally on a stock gasket. Any more than 9.0 on your stock gasket is asking for it.

Depending on the transmission (among other variables) the stock boost level should be as follows:
6.8 PSI Max (5 spd. manual) delivered with 7.4 PSI @ the wastegate actuator

5.5 PSI Max (Automatic) delivered with 7.4 PSI@ the wastegate actuator

These are the advertised boost PSI levels from the factory. These numbers will vary within reason. I'm not sure of the actual boost levels to expect from shim thicknesses, but these numbers should give you an idea about how much the actual boost number drops off from the wastegate actuator PSI level and should give you an idea on curve and what to expect from the different shim thicknesses. Again, I used 3mm thick washers, so measure yours if you want to use this table as a reference!

I hope this information helps anyone looking into shimming the wastegate on their CT26.

 

[lagged]

I actually used my Mityvac and performed a pressure test with different thicknesses of shims. I used the pressure side of my MityVac and attached it to the wastegate actuator. I also used my pressure/vacuum gauge tool in between the wastegate actuator and the MityVac tool to read pressure.

I applied PSI to the wastegate actuator until I saw the TSRM recommended amount of movement in the linkage and recorded the PSI readout on the gauge. I performed this test with approximately 3mm increments of increased shim thickness (approximately the thickness of 1 washer) and these numbers are the mm @ PSI when the wastegate was opened. Basically performing a TSRM wastegate actuator test at different shimming levels.

Here are the numbers that I recorded from a stock CT26 bench test:

-Stock (no shims): Wastegate begins opening @ 7.4-7.5 PSI
-3mm shim (1 washer thick): Wastegate begins opening @ 7.7 PSI
-6mm shim (2 washers thick): Wastegate begins opening @ 8.2 PSI
-9-10mm shim (3 washers thick): Wastegate begins opening @ 8.8 PSI
-12mm shim (4 washers thick): Wastegate begins opening @ 9.6 PSI
-14-15mm shim (5 washers thick): Wastegate begins opening @10.7 PSI

As you can see, with more shim thickness, the PSI steps become steeper.
This is due to the increased curve in spring tension holding the wastegate actuator in the shut position.

I stopped testing at this point because the TSRM (toyota supra repair manual) factory recommended test says that you should never apply more than 11.4 PSI to the wastegate actuator for testing to prevent damaging the actuator. This is of course with no shimming at stock level, but I decided not to push it's limits.

I would imagine that the wastegate actuation PSI levels would be close to that of the boost limitations.

If you have replaced your stock head gasket with a stock replacement, you can safely run about 9.5-10 PSI. With the stock gasket still in place, I would not run any more than 8.5 PSI MAX. IMO, I wouldn't run any more than 8.0 PSI personally on a stock gasket. Any more than 9.0 on your stock gasket is asking for it.

Depending on the transmission (among other variables) the stock boost level should be as follows:
6.8 PSI Max (5 spd. manual) delivered with 7.4 PSI @ the wastegate actuator

5.5 PSI Max (Automatic) delivered with 7.4 PSI@ the wastegate actuator

These are the advertised boost PSI levels from the factory. These numbers will vary within reason. I'm not sure of the actual boost levels to expect from shim thicknesses, but these numbers should give you an idea about how much the actual boost number drops off from the wastegate actuator PSI level and should give you an idea on curve and what to expect from the different shim thicknesses. Again, I used 3mm thick washers, so measure yours if you want to use this table as a reference!

I hope this information helps anyone looking into shimming the wastegate on their CT26.

i am not so sure i agree with you on that. if a new, OEM head gasket is installed with ARP studs and torqued to ARPs reccomended value of 72 foot pounds of torque i would think that if you keep detonation under control that you could safely run at least 15 pounds of boost on the stock turbo. (forget about how long the stock turbo would last at that boost level)

 

[MisterTurbineTwister]

I agree that the stock HG can withstand 15 PSI, but for how long, I don't know and my point is just that. 15 PSI can be achieved on a stock replacement gasket torqued to 75ft lbs with ARP fasteners, but I wouldn't trust it. Not to say that it can't be done. It can. It's just not a good idea.

Going with ARP studs or bolts does improve the hold down to some level, but I have yet to see someone who was pushing 15 PSI on a stock replacement head gasket any longer than 10,000-15,000 miles after the mod.

You're right about the turbo not holding up under those numbers too.

 

[americanjebus]

another factor like you mentioned misterT is the trannsmission,
i for one am hitting a moral brick wall with shimming, i havent and want to hold off from it because i have an auto. right now w/ intake and exhaust work that is enough to reach the reliable limits of my auto tranny,
shimming would be at 8psi max for me mainly because i only have a replaced oem at 74lbs of torque.

reliable shimming of wastegate in my opinion is going to change from car to car, some of you w/ 5spd and metal hg could very well push the 15.

my tranny bassicaly keeps me from modding my car, all i can do is start looking for a tranny cooler and hope for luck in keeping it alive.

 

[Allan_MA70]

dont bother with shiming just go for a bleeder (cost all of $10aud for the valves) runs all the time 10psi + with a trans cooler (allso runing 1UZ-FE afm, 45psi fuel pressure + 440cc injectors) but after 13 psi with the stock cooler and turbo the air temps AFTER the intercooler are about 75c !!!

here is 10 psi...

(right click.. save as..)
http://members.optusnet.com.au/ma71/10buckbleeder.MOV

the bleeder..

 

[MisterTurbineTwister]

I wouldn't dare shim a wastegate on an automatic transmission car. I have seen N/A engines driven hard and destroy the automatic in these things. I think anyone can safely shim or otherwise adjust the opening rate of the wastegate actuator up to 8-8.5 PSI safely with a good clutch and a new stock replacement head gasket torqued to 72ft lbs, even with retorqued original bolts. Just don't plan on ever using them again in the future.

I would first recommend going to a bigger intercooler, a higher flow filter system and a bigger exhaust due to the compressed air temp like Allan was explaining.

Do the dumb things first before touching fuel and boost levels or pay the consiquences of skipping them.

 

[americanjebus]

yea the auto in this is pretty good for an auto but yea its just a matter of time before it gets blown to hell from just some basic mods.

 

[MisterTurbineTwister]

You're right about that, Jebus. I have an automatic in my Cressida with the 7M-GE and it's okay, but I wouldn't dare beat it.

We've got the American Jebus! See him on the interstate...

 

[Allan_MA70]

pffft mines an auto i thrash the shit out of it ALL the time... stalling it... few drag runs its still ok

right click... save as...
http://members.optusnet.com.au/ma71/AllansMA70smoke.wmv

 

[MisterTurbineTwister]

You must have been the previous owner of my Cressida Allan! I spent about 20 hours and $300 on my transmission rebuild.

"You can pick a fight with a gorrilla if ya want to... but that don't make it a good f-in' idea!" Chris Rock

 

[Mk3 TurboS]

Just one thing to remember if you shim (correct me if im wrong). If you shim stock (no exhaust, intake, A/M FMIC, hard pipes) each time you add a BPU mod it will also bump up your boost just slightly. So if you shim close to fuel cut, each time you mod, you will have to DE-Shim in order to stay under fuel cut.

On another Note, I want to get rid of my Blitz MBC in the near future cause it spikes, I want a Apexi EVC but there pricey. Any suggestions on an older model EBC that is basic but affective with 2 stages of boost?

 

[americanjebus]

We've got the American Jebus! See him on the interstate...

heh its jesus in the song,
"he helped build the presidents estate....."
your the first person to make the connection between my user name and bad religion.