schnellfahrer

I haven't had time to install the lambda sensor yet, but just logging rpm, boost and tps gives some interesting results. The plot below is in 3rd gear, wot from 2000rpm to 5000 rpm. 1Bar at ~3300rpm. 17psi at 3600rpm. Already at 4200 rpm I'm below 16psi. Is this the characteristics of the 26/6?
This is with Guru 18psi chips, Guru Wastegate and Lindsey cbv.
This is really bad. I need to get the lambda sensor in quick to see what's going on. What do you think is causing this? Very rich, or very lean?

Any input is appreciated.

Sam Lin

Boost loss could be your wastegate as well, though the K26 does indeed roll off quickly - what boost controller is driving it?

Sam

Jake951

The boost dropoff is probably the turbo and not the wastegate (Guru WG). You may recall my recent thread on the Tial WG installation. Afterwards I found that there was absolutely no difference between the Tial and Guru WG's. In my case I'm running the K26/8 and the boost rolled off with both WG's.

schnellfahrer

I use the AccuBoost and the CV is bypassed.

Duke

If you have a rebuilt wastegate is should not be rolling of like that. But I think it's a combination of bad wastegate and turbo.

As a coincidence I tried datalogging with my MAP-kit for the first time this evening.
I on the stock wastegate (shimmed) and also using a reliaboost. With my K27/8 and MAP I got similar numbers as you. 15 psi at 3300 rpm 17 psi at 3600. Boost dropping to 15 psi at redline.

shaheed

duke, how are you approaching 400hp if the boost is only 15psi at redline? is your wastegate stock btw?

schnellfahrer

The 26/6 should spool quicker than the 26/8. I got a plot from a friends car (26/8) and his plot looks alot like mine; boost threshold and drop off are more or less identical.

hosrom_951

I suspect a 'tired' turbo to be the fault there.

My stock K26/6 (and almost stock car) hit's 11psi and rolls off to 9psi over 5,100rpm, that's with a stock WG as well, no shims.

Duke

I actually don't claim to have 400 hp yet, but bit by bit I'm approaching that level

The boost is around 18-19 psi (1,28 bar) in the midrange and drops of above 6000rpm. With a new wastegate and 19-20 psi all the way I'm confident 400hp will be no problem with this engine.

Here's a graph:

shaheed

do you have a 2.8l or something? didn't a similar guru setup with k27/8 and modified internals (according to tony G) make only 370rwhp at over 20psi? i'm not doubting that you will, i just want to understand how you're going to make that much power with that setup.

Ben Z.

duke, no info on the boost drop-off, but you might want to try posting graphs versus rpm instead of time, as that might be easier to read.

Duke

I was talking about BHP and not WHP
In other words 340+ rwhp, if I'm not there already I don't think I'm far away.

Duke

Ben I did a couple of graphs like that at first but actually found this to be easier to read since it show the rpm rise. But I'll give it another try.

shaheed

ah i misunderstood you i agree, once you get that wastegate issue cleared up you should probably be in that neighborhood.