Holy mother of pearl!

That's awesome Sav.

 

I picked-up 800rpm of spool going from the BEGi log to the AF stuff.

 

Yeah but I have a tubular equal-length exh manifold, a 3" Enthuza exhaust, a EBC/MBC, a 0.64 AR turbine housing, and a good tune.

Just found this. Here is another 2871 reporting excellent spool with a BEGI cast manifold.
https://www.miataturbo.net/showpost....5&postcount=23

 

VVT is worth 500-600rpm of that, the AF is worth the rest. It's more than 800rpm too because I'm spooling a .86 A/R housing.

Timing map is hurr. There's not a lot of effort into this vs. the last time I was on the dyno, mostly in the 5000-7000rpm range and 211/225 rows. E85 + low-comp = lots of timing. I never heard any detonation, but I will pull the plugs to confirm that since the car is so loud.

 

What was the duty cycle with the ID1000's and what base fuel pressure were you running?

Thanks,
--Ferdi

 

Awesome, I want that...

 

ZX, post your boost curve starting at 2000rpm and ending at redline. The torque curve from your dyno chart indicates that the boost might be coming in really slowly. It shouldn't bell-curve like that, it should rise and then flatten out like turns101 and my graphs do.

 

i wouldn't know about that. I started with a equalish-length long tube manifold. I'm sure that's why I dont complain much about the 2876 spool.

 

Yeah it is a bit weird I agree. It is not the boost curve since that builds and holds (stays flat) very nicely.

I found a couple of things since the dyno session that could explain it. I might have to go back for another tune session. Anyway, not trying to jack the thread, sorry.

 

BTW have you tried futzing with an exhaust cam gear?

 

I have not. Have you? Any gains?

 

Very interested as well, I would think the 1000's would start to run out to steam at that power level and E85.

 

Yes, with my wee GT2554, but not on a dyno. It helped spool at the bottom, and topend both, when I advanced it by 5* (crank). The gain in topend was shown with street-logging-"dyno" runs - the torque didn't drop off as much. However, I couldn't tell you if it lost midrange. The spoolup was the most noticeable effect, and I liked it so I kept it. It also raised EGT though, but with you and E85 it should be a non issue.

BTW do you know of anyone naturally aspirated who's tried your intake manifold or similar?
In theory the manifold operation doesn't get affected by being boosted or not - IOW the same % topend gains should be visible in an N/A car.
UNLESS... there's a 2rd order effect where an n/a car's exhaust scavenging interacts with the intake runner resonance which isn't present with turbo cars.

 

Sav, I too am very interested in the duty cycles and base pressure question that was asked 3 times already. I don't have an afpr and am wondering how long I'll be able to go without one (or how high in power) before I'll NEED one.

Oh and just wondering: how much did you have to add/adjust the fuel map for e85? Just 30%?
Did the cranking enrichments have to be bumped up a ton?

 

AEM does cranking enrichments as a percentage of the fuel map so there was no adjustment necessary. I did add about 20% to the fuel map as well as the base pressure bump (43psi to ~70psi).

I don't know the duty cycles off the top of my head and I can't pull logs from the AEM (I think my USB adapter corrupts them but I'm not sure). I will take a laptop log this weekend at an autocross and let you guys know what they are.

 

Great. Thank you

 

I was cleaning out my room today and I found my old 2554R dyno chart. The low-end torque comparison is super interesting so I charted it. The 2871R combined with a low-comp motor and E85 gives nothing up to the 2554R down low and absolutely destroys it up top.



Full setups are as follows

GT2554R:
-stock '99 longblock, stock head, stock cams
-'99 IM w/ VICS switchover at 5000rpm
-3" catless Enthuza exhaust
-MSPNP, pump gas

GT2871R:
-8.6:1 shortblock, stock VVT head, stock cams
-Blox B18 IM, B18 TB
-open 3" exhaust
-AEM
-E85

 

big turbo wins again.

i noticed myself using the exact same manifold but with having been converted to TiAL turbine housing that you can spool up faster.

both of my setups used the same wg and spring, but one was a 2860RS and one was a 2871R both 0.86 AR housings. the 2871R map log looks identical to the 2860 but it obviously flows more.

 

New or old exhaust manifold?

 

Yeah, I did forget to mention that. The old 2554R chart is the old BEGi setup, the new 2871R chart is my ballin' AF setup.