I know about the whole set the wastegates so they crack at 12 psi thing.

But can the upgraded wastegates be set too high? My car hits 1.2, then 1.3 for a flash (sometimes), then resets to 1.1 and gets to 1.2 again near redline.

Seems to me the wastegates are doing their thing, bleeding off too much exhaust, then closing back up near redline.

The whole thing is very apparent here in the dyno graph. Notice the dip and regain near the top of the rev curve. BTW this seems pretty typical TT behavior.

http://members.dslextreme.com/users/...11%20Turbo.jpg

1. are the factory actuators too slow?
2. Will backing off the wastegates alleviate the dip? and will this lose mid range torque and throttle response?
3. will a Greddy EBC with fuzzy logic do better ?

 

Did you log boost on the dyno? I would confirm that it is boost related before changing anything.

 

No, but I see it on the dash gauge. On the day of the dyno, it did 1.1, 1.0, 1.1

a year later and some wastegate tweaking it goes 1.2, 1.3 (sometimes), 1.1, 1.2

From what I've seen it's very typical for stock modded TT to dyno this way?

 

They all dyno like that. There is a dip right before redline. I think it's the ECU's safety mechanism. Engine self preservation. Here is my last dyno.

 

Thanks

K24 car right? It's definitely not ECU preservation, it's the wastegates working. Bleeding exhaust and then closing back up and spinning up the turbos again.

I'm just trying to figure out if tighter or looser wastegates or EBC will minimize the dip....

Get some upgraded wastegates or wastegate springs, just look at the difference in the midrange. You will love it! It will have better throttle response and much stronger midrange.

 

It's the waste gate, the problem is that the "gate" is a flapper valve, when it "pops" open you get pretty good drop in boost pretty quick. It's the nature of the beast. When I built smallblock and bigblock turbo chevy's for boats we did one of two things, one was to use a little more turbo than the motor could hold, ie, bleed off boost all the way up the curve thus we had pretty steady boost pressure. The second and far harder thing was to have the turbos sized perfectly to the motor so as to basicly not have any wastegate opening until the engine reached redline. We also tried a "slide valve " type wastegate that was handmade with a very accurate electric solinoid controling it, worked really good but as far as I know was never produced. But this was all quite a few years ago. Now I just live with the dip.....

 

Yes, K24's on my Gt2 with an Orton flash, Europipe II, DV's. That dyno was prior to the EVO wastegate installation. I've haven't put her back on the dyno to see if there is any difference. The car does hold boost better (1.1-1.2) and the boost comes on quicker; definitely the best modification for the money. I should of listened to many members on the board about this a long time ago. You being one of them, Markski and others too.

 

ANother think to consider is and not sure if anyone pointed it out that if your running in california on 91 pump and expect to cranck up the boost to 1.2 or 1.3 bars dont you think that the dip may be from the ecu pulling timing??? you should run 1.1 max on 91 octane... thats just my opinion..... and the minute you put in the upgraded WGs you will run considerably more boost period...
The stock WGs are doing the job.... they will never hold 1.2 bars constant... never especially on k24s with a flash.
I would get the upgraded WGs and get the car to a dyno and have the car run so that you dont lean out nor pull timing...
markski

 

Thanks for the input.

To be clear, the dyno run IS on 91 octane with upgraded wastegates. You can see the A/F ratio on the graph but not timing of course.

 

well if you have dips in the graph thats probably because the ecu is pulling timing. I doubt its N75 valve related or WG related...
You should go back tot the same dyno and run some 100+ gas and then compare....

 

I'm inclined to this theory.


But Markski knows his ****. so... will do. thanks.

 

I am running 97(RON) like 93 US with big EVO IC's and I always see 1.3 bar from 3,600-4,600....then 1.2 to the red line.

Very very hot days 1.3 is always there but just a simple spike. (same range of RPMS)

and Very very cold days some(1/10) times in 5th-6th gear I see an spike of 1.4 for milisecond..then 1.2.

I think you need to define where and when you get the 1.3 bar.

 

Before anything... I would get the WGs checked out.. make sure they both open up at the same rate.... make sure you DO NOT have any boost leaks.... do a boost leak test- very simple if u know what ur doing....
assuming everything checks out then do a dyno pull on better gas.... then compare the dynos... if it still doesn't look good then IDK.
BTW, do you have the flashloader with the race file?

Then I would still not run 1.3 bars on 91 octane.... but that's just me.

 

Never thought of the timeing issue,or boost leaks, thats what I get for working on primitive American V8's.........lol............I had to assume that all of that stuff was checked and rechecked before your session, sorry i've built to many racecars.
Listen to Markski, he knows his stuff.........

 

LOL I'm far from being an expect on this... I just went thru a 6 month agony doing upgraded springs and trying to dial them in 3 years ago... had 3 different ones in total... I'm sure there are some more knowledgeable guys here ....