"Blown" motor teardown

I know stock we only run .3 points of lower compression than non-Sis. You going lower on the rebuild? I know DI allows for running higher CRs to more efficiency. Still, if your goal is running all the boost ever and throwing meth on top for supplemental fueling/knock prevention... I didn’t know if you were going to go as low as you could go for CR. I was shocked how high the CRs were for all these cars after owning so many 80s and 90s turbo Zs with much... much lower ones.

charleswrivers said:

I know stock we only run .3 points of lower compression than non-Sis. You going lower on the rebuild? I know DI allows for running higher CRs to more efficiency. Still, if your goal is running all the boost ever and throwing meth on top for supplemental fueling/knock prevention... I didn’t know if you were going to go as low as you could go for CR. I was shocked how high the CRs were for all these cars after owning so many 80s and 90s turbo Zs with much... much lower ones.

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That's why dsm engines take so much boost/air. 7.8:1 factory compression lol.

I would hope he didn't. I can't imagine the off boost response dropping compression on these things.

Honestly the stock block held up pretty well. You should be perfectly fine staying within your stock fuel system. Which on the gtx2860r, I believe that's 28ish psi. Which was plenty! But I got greedy. Hell if I wasn't sure I'd crack the manifold @40, I would of sent it there for sure.

There are also examples of people pushing there car harder then me and the motor handled it.

I stayed with stock compression.

I'll be switching my meth system up just a tad. I'm ordering a spare intake manifold, I intend to tap the runners for a 4 port system. I'm at 375ml rn,
I'll go to a 100ml/min nozzle, which should work out to 400 ml/min.


This is what I decided to go with. TSP was very helpful. And I'll sleep good at night knowing the block will handle my goal.
https://www.twostepperformance.com/products/built-l15b7-1-5l-civic-for-the-2016-honda-civic

Yeah my Z32 is 8.5:1. It also only runs 9.5# stock.

These tiny turbos pushing low flow but ridiculous high pressures blow my mind. I guess that’s how you can not only have reached peak torque but be past it on a Civic as my Z is getting into threshold at all. Even running higher boost, I’m still only essentially making roughly what a stock L15B7 makes... as my 3.0 is acting like 2 split 1.5 banks with their own turbo. I’d have to make ~750-800 whp to make what displacement-wise @kshawn was doing. Still, the turbo options for the old VG engine always seem to be after high flow, lower pressure. Teens and 20s... but 30s? Can’t recall ever hearing pressure numbers so high.

On a Z31 It was just 6.7# on a Garrett T3... 7.8:1 CR. No intercooler. The pressure rise was so low, they weren’t needed. Those cars also made less power than a stock Civic Si... with double the displacement and 1/2 again the cylinders, so there’s that.

I really find these 300+ numbers wild on such a small motor. It’s impressive. I hope your new build goes well, you manage to well exceeds your old dyno... and it last for a long, long time.

With a PR of about 2.9 on the 2860; what Octane were you using to Max the CFM from the Turbo? Because @65-66% efficiency you were just reaching about 350CFM.
I totally get your “goal”, but leeping that 2860 at about a 2.5PR would be your best “Meat n Potatoes” don’t ya think? More efficiency without needing meth?
Eh..who am I it’s not my car
**EDITED**
I only say this because at the PR you were at on that 2860, you would obtain just enough CFM @70% to make the dyno power you posted; which would be about 245CFM. If you want more, you really should increase the size of your tubine to help you up top with a larger A/R. Slower spool yes, but much stronger up top when winding it out.

My gf won't let me get a bigger turbo, that's why.

Plus from what I can tell I would pay 1550 if I wanted to pop a bigger one in. Maybe down the line I'll sneak one in.

kshawn said:

Maybe down the line I'll sneak one in.

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(Insert inappropriate joke here)

Play your cards right on this Valentines Day with the lady.

Bahaha

For more context. This is a snap of what I was doing when she let go. Take note of 4th gear uptop.

How come the maf readings+mg/stroke (cylinder fill)+commanded boost are so close to standard reflash numbers at 31psi with a large frame turbo? I would think the computer would need to know this data and they should be reading significantly higher should they not?

Weird.

Also on a minor note the recirc valve doesnt seem to be keeping up (large boost preesure spikes at the end of each gear). Probably unavoidable when using the factory recirc valve if that is what your using combined with the big turbo kit.

PowerPerLiter said:

How come the maf readings+mg/stroke (cylinder fill)+commanded boost are so close to standard reflash numbers at 31psi with a large frame turbo? I would think the computer would need to know this data and they should be reading significantly higher should they not?

Weird.

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Because of the meth. To account for the added fuel, value needed to be removed from the MAF scale, which skews the reported airflow/cylinder fill.

One of many reasons why meth injection shouldn't really be used with the stock ECU. There is no good way to use it properly, especially when spraying large amounts.

PowerPerLiter said:

Also on a minor note the recirc valve doesnt seem to be keeping up (large boost preesure spikes at the end of each gear). Probably unavoidable when using the factory recirc valve if that is what your using combined with the big turbo kit.

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The factory recirc valve isn't used with the PRL kit.

If you look at pretty much any 10thGen running big boost, the TC pressure sensor spikes on rapid throttle close; the sensor is literally located inches in front of the throttle plate, so it's silly to think the bypass valve located at/near the compressor outlet would be able to evacuate and equalize pressure immediately, regardless of size.

Just a simple question looking at the datalog from someone trying to learn...



What caused it to overshoot the 21.7 psi target by nearly 10 psi?

gtman said:

Just a simple question looking at the datalog from someone trying to learn...

What caused it to overshoot the 21.7 psi target by nearly 10 psi?

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Boost is not being controlled by the ECU. His is an old kit that uses a mechanical, pneumatic wastegate with external control.