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Here's my bias duty table. The 180, 210, and 240 rows are decently well tuned. 270 and above I haven't tuned properly (I did some quick hacks to it on the dyno, but it needs more), and 160 is below the 10 psi spring that I currently have installed.
This porting is harder work than I anticipated. These so called "Tungsten Carbide" dremel bits from Amazon seemingly only last 10 seconds each. I'd have thought a pack of 20 would at least be enough for this one job. Does anyone have any other recommendations? I only tried Amazon since I wanted it next day (to do this weekend) but looks like it literally isn't going to cut it. The UK is awful for trying to get usable tools (ie not eBay/Amazon fail specials but not full on Snap On baller glory). There's no equivalent of Harbor Freight here!
Originally Posted by codrus
Here's my bias duty table. The 180, 210, and 240 rows are decently well tuned. 270 and above I haven't tuned properly (I did some quick hacks to it on the dyno, but it needs more), and 160 is below the 10 psi spring that I currently have installed.
--Ian
Thanks, that looks like a good amount of resolution. I know that EWG is ultimately the answer....
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Those you bought are HSS.
That title is not just misleading but wrong. You want to spend around $50-$60 for a set of 5. So what's that like 40 pounds? You also want double cut, they work better.
That title is not just misleading but wrong. You want to spend around $50-$60 for a set of 5. So what's that like 40 pounds? You also want double cut, they work better.
Do you mean in the bit where it said material HSS? I thought it was Carbide embedded in the tips of an HSS bit? Though they definitely cut like HSS....
Thanks for the tip on double cut, I thought it was double cut only for softer materials? Well it looks like it's worked for you!
Ah well, there's a £34 set I can buy locally. Will see if they have stock.
I would look closely at the turbine housing and how it mates to the down pipe elbow. I suspect most of your problems lie there. Without good wastegate/downpipe separation at the turbos you lose scavenging effects of that elbow design. The turbine is free to pressurize the backside of the waste-gate. Even with that you still have to port the wastegate for lower boost numbers.
While most fight boost creep on t25 internal wastegate housings yours is quite extreme. The most glaring difference is that turbine housing of yours.
Ill trade you for my gt2560, I used to have creep and I ported the **** out of it over the winter. Now I hit 16psi and taper down to 14.5 by redline. I have a 7psi wastegate spring and I ordered a 14psi can so my problem should be fixed, but the port work makes all the difference. I dont have pictures of exactly how I ported it, but start at the turbine inlet, and port a channel all the way to the wg hole, then enlarge the wg hole as well. Dont take out too much material make sure the wg poppet still seals.
TL,DR, issue fixed, went from ~18psi @ 6.5k to ~6psi.
Thanks for everyone's help regarding the tools. I ported quite a lot out of the housing (and a bit out of the DP) and now I measured 6.2psi @ 6500rpm (down from ~18psi before) with the WG wired open, and 9.9psi @ 6500rpm with the can connected. I guess the WG has to crack open fairly far to get significant flow at high speed (7mm from my data earlier...)
One question I've been left with though is whether I'm getting knock here. The knock readings look like they could be saying something, but does anyone get knock at 140kPa, 20 deg spark, 12:1 fuel, 9:1 compression and 99 RON fuel?!
I managed to get some that looked similar to your die grinder ones. Wow. They were so much more effective than the originals I had bought. They left my turbine housing and DP looking like this. I took a lot out of the angle between the WG hole and the turbine inlet, though that's not easy to capture in a photograph.
Originally Posted by k24madness
I would look closely at the turbine housing and how it mates to the down pipe elbow. I suspect most of your problems lie there. Without good wastegate/downpipe separation at the turbos you lose scavenging effects of that elbow design. The turbine is free to pressurize the backside of the waste-gate. Even with that you still have to port the wastegate for lower boost numbers.
While most fight boost creep on t25 internal wastegate housings yours is quite extreme. The most glaring difference is that turbine housing of yours.
Thanks you. I ported the DP to line up better with the turbine and it looks like it worked.
Originally Posted by andyfloyd
Ill trade you for my gt2560, I used to have creep and I ported the **** out of it over the winter. Now I hit 16psi and taper down to 14.5 by redline. I have a 7psi wastegate spring and I ordered a 14psi can so my problem should be fixed, but the port work makes all the difference. I dont have pictures of exactly how I ported it, but start at the turbine inlet, and port a channel all the way to the wg hole, then enlarge the wg hole as well. Dont take out too much material make sure the wg poppet still seals.
Thanks, I followed that technique. Looks to have worked!
08-25-2018, 04:09 AM
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