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I suggest to check your IWG spring and perform a boost leak test. For an EFR8374 on RB26, boost should be well on around 3500rpm. 4000rpm is a little bit late

Thanks

Spring is the high boost cannister on 3 turns. In 3rd and 4th it will come on around 3700 etc. My car is a stroker, but stock bores so I'm bit gaining much displacement. Low compression, ported head, big valves, Tomei poncam A (small ones) not indexed yet (0 and 0 settings), also my squish pads are removed.

I'll check those hopefully this weekend and let you know what I find. I'm sure the cam changes will help.

When you say "it comes on at around 3700rpm", so this is not full boost? On a stroker RB you should be seeing about 20psi at that level.....On a RB30 I'm seeing 22psi by 3400rpm.

  • Like 1

When you say "it comes on at around 3700rpm", so this is not full boost? On a stroker RB you should be seeing about 20psi at that level.....On a RB30 I'm seeing 22psi by 3400rpm.

Correct.

With cams set to '0' and '0'

In 3rd gear from about a 25 mph punch (1,900 rpms) I will have the following with the electronic EFR wastegate solenoid bleeding boost:

3 psi = 2684 rpm

5 psi = 3046 rpm

10 psi = 3566 rpm

12 = 3713 rpm

13 = 3827 rpm (at this point my closed loop boost is activated and starts dropping duty to anticipate the "spike")

16 = 4030 rpm (duty is down to 14.5% bleed)

Time to go from 2500 rpms to 4000 rpms = 3.415 sec (for whatever this is worth).

With cams set to IN+2 and EX-4

In 3rd gear from about a 25 mph punch (1,900 rpms) I will have the following with the electronic EFR wastegate solenoid bleeding boost:

3 psi = 2689 rpm

5 psi = 3076 rpm

10 psi = 3636 rpm (new boost settings duty cycle starts dropping here to control spike better).

12 = 3785 rpm (boost duty dropped to 27.6% bleed here)

13 = 3883 rpm (at this point my closed loop boost is activated and starts dropping duty to anticipate the "spike")

16 = 4137 rpm (duty is down to 17.8% bleed)

Time to go from 2500 rpms to 4000 rpms = 3.152 sec (even though slower boost, the car is quicker by a marginal 1/4 of a sec)

From what is a pretty extreme change in cam positions, I didn't gain on boost threshold (even though I shortened the Lobe Separation Angle by 6 degrees!) but the car was a bit quicker. Now at these low rpms I'm sure this data isn't 100% perfect data, but you get the point that a pretty extreme cam changed (+2 intake and -4 exhaust) didn't bring down my boost threshold. Later I will try a different method by going back stock on the LSA, but moving both cams slightly advanced to see if it will spool quicker.

I'm also on 93 octane pumpgas and low compression ratio. Also on the Hpertune V2 90mm TB and ported head. I also have the squish pads removed so perhaps I'm just going to wrong way with my build and should start aiming for increasing top end power. The 4k is totally livable...and transient response from this turbo is absolutely incredible, but yes, I did expect more bottom end. Perhaps I have an engine issue, but CR and valve clearances came back good on tests. Car seems to be very fast.

post-136202-0-17911100-1467053065_thumb.jpg

How low is low compression?

When is it going on the dyno for a proper tune?

4th gear will spool considerable earlier FYI. 3700 rpms is 15.1 psi...easily would see 20 by 4k in 4th just ramping it up.

My cold compression numbers from a couple weeks ago. I think I'm around factory CR...didn't honestly finish the calculations, but with the decking and valve relieving in the head and the squish pads gone it seems about right with the pistons I ordered.

1 - 165

2 - 170

3 - 165

4 - 172

5 - 170

6 - 170

Just went and set cams backwards a bit by lengthening LSA... Exhaust 2 deg advanced, Intake 2 deg ret. Car definitely idles better and drives smoother, but again seems noticeably weaker in the mid range but very strong on top. Boost threshold is about the same...no real changes otherwise.

But sticking to the thread my 3rd gear time while rolling in from low rpms (like 3k) and timing from 4500 rpm to 8k rpms is 5.184 seconds if anyone can get data at 16.5-17 psi (waves a little) from some logs I would appreciate it.

Spring is the high boost cannister on 3 turns.

the high boost canister is sprung fairly conservatively - i typically like to run 6-7 turns of preload on it. Or a turbosmart 26psi IWG with 4mm preload

  • Like 1

the high boost canister is sprung fairly conservatively - i typically like to run 6-7 turns of preload on it. Or a turbosmart 26psi IWG with 4mm preload

I added 3 turns to it...it did help a tad for sure but still starting at 2k rpms in 3rd gear equates to 17 psi at 4,200 rpms with the cams set like they are still.

I added 2 logs of the same pull - Yes I see it's rich on spoolup just wanted to make sure to include throttle position, rpms, boost, ignition advance and boost control output. Also note it just "touched" my knock limit at around 4200 rpms and ended up pulling timing (pulled 4.5 deg is what I have it set to) because I have it pulling at anything over a knock count of 100. It was 104 and then it pulled so the timing map is usually set at the difference between the ignition advance and the amount pulled (4.5 deg) - hence the dip in my timing after 4200 rpms.

Even though idle was a bit rougher with the cams the other way, the car was faster for sure on bottom and mid-range. I'll get some more logs tonight to compare. What I think I may end up with is cams at base separation but both cams advanced (maybe 3-4 deg advanced each cam)

Also I definitely will do a boost leak test this week.

And one more thing, I'm only on 3" exhaust...but it's pretty well made 3" with minimal bends and is all mandrel throughout. I'll be going to 3.5" later, but didn't think that would be a big restriction to spoolup at this point.

Also note I am on PUMPGAS. I know E85 is much better, but I don't have access to it here so I hope you guys aren't comparing my numbers to E85 spoolup times.

post-136202-0-22487000-1467123448_thumb.jpg

post-136202-0-02492900-1467123454_thumb.jpg

post-136202-0-15589800-1467124447_thumb.jpg

How much timing are you putting into the motor coming onto boost?

About 30 deg at 7 psi - look at the pictures above. Forget the dip in that chart there was a touch of knock at 4200.

Take some timing out.. try at 0kPA at 30 degrees and drop it so by 0.5bar you're under 25 and by 1 bar you're under say 20.. I think you have too much timing for premium unleaded fuel... and potentially noses over MBT affecting your spool and causing knock.

Stock knock sensors...great is there more I don't know? I'm trying to tune for zero knock and have been pretty successful so far. Cam changes are changing what timing I can run fyi.

Just ran another log. 5th gear easily hits 17.1 psi at 3500 rpms (almost exactly). Just hard to make it hit the numbers in 3rd gear...it's around 4k every time.

I'll post some videos in a bit.

food for thought (feel free to ignore).

advance the intake around 3~4 degrees, retard the exhaust say 2

run less timing, like 10 degrees less that whatever you have at the moment

lean it out coming onto boost

so at 0kpa you're say 13:1

by 100kpa you're about 12.5

past 100kpa 12

past 120kpa under the 12s

I will try them.

Videos of how the car drives. Also added a screenshot of a log of a street pull I just did on my 255/40/17 hankook RS3's.

1st through 3rd to redline in 3rd (8k) from dead stop is 9.0 seconds.

a little first gear punch from low rpms and roll through a couple gears

3rd gear pull

3rd gear threshold test.

post-136202-0-95377500-1467179169_thumb.png

Tom is yours a T4 TS IWG ?
Did you run the stock actuator and or have any issues with boost control ?

For anyone interested, here is my 7670 dyno graph.

Car is an Evo V. As you can see, it's fairly responsive.

Not pushing it at all on 98, only 20 psi.

attachicon.gifEvo_98.jpg

For anyone interested, here is my 7670 dyno graph.

Car is an Evo V. As you can see, it's fairly responsive.

Not pushing it at all on 98, only 20 psi.

attachicon.gifEvo_98.jpg

2.3L and T4 twinscroll innit http://www.sau.com.au/forums/topic/451166-post-your-evo/page-3#entry7752674

Still, spools super super early.

Edited by Skepticism
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