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Can you help me with compressor maps? Does the map tell me how the pressure ratio effects the airflow? If I need 40 lb/min for 340whp, how do I know what pressure ratio that will be at?
If i was at 22psi (2.5 pressure ratio) flowing the 40 lb/min, this turbo would be most efficient and have plenty of headroom
You shouldn't need 40lb/min to make 340whp on a properly flowing system and e85. You should be able to make it with 35ish. A few degrees higher AIT's due to smaller turbo makes almost no difference on e85, but response will be numbed down due to the oversized compressor. What cordus was getting at is that you should run the smallest turbo needed for your goals, and running these new fancy billet wheels at the top of their efficiency is actually nothing bad at all. If he hits 340 on his, then you should easily beat that on a full tubular setup and e85, and have much better spool/response/curve.
Also keep in mind compressor map is just part of the equation. The other part is turbine/hotside, and then your engine/head/cams/etc when it comes to end result power output.
1. Throttle body not opening fully
2. Cam timing
3. Intercooler - compare size/design to others
4. Downpipe - sucks, but is it the real problem?
5. Double check base ignition timing
6. Make sure there are no funky settings switched on in MS
7. BOV - block off to test if it is leaking
8. ?????
Conservative dyno? Is 262whp @ 15psi with a reasonably sized turbo on a low compression BP really that out of the ordinary?
I see you dyno'd on Halloween last year and I distinctly remember it being 90 degrees with 800% humidity when I took my daughter trick-or-treating that night. I'd assume you had similar weather which was not exactly conducive to outrageous power numbers.
Welp, the extraordinarily loud American Iron Mustang 4.6 that dyno'd just before me was only making 23Xwhp and the operators were amused that my car put down better numbers.
But if you look at the RPMs of the curve, the peak is way too low, even for a log manifold. I agree with the analysis that something is holding it back.
Do you have a cat on the car, or is it a test pipe? If it's got a cat, then I'd say it looks about right to me. It's 70 ft-lb per L-atm (assuming MAP of 200 kpa), so the torque is right, and it's making 5% more power than torque. That's about what I'd expect for a Miata with stock cams, a stock intake manifold, and a 94-97 head (even a P&P one).
For reference, here's a comparison of my car at 190 kpa (closest I have to a 15 psi run) with the FM 3" ceramic core cat and with with a test pipe in racetrack configuration:
Many of the japanese mufflers are not nearly proper 3" straight through because they are trying to comply with JASMA restrictions, many many hotdogs on high end japanese systems have incredible restrictions and go down to as little as 2.25", and are infact not hotdogs at all.
Codrus is running 6.5 to 7.5 degrees more timing in the 240kpa row of the map. I'm using 8.4 pistons and pump 93 octane so I don't know how much room I have. I guess I should break out the electronic det cans and do some more testing. I won't until I check cam timing though.
Codrus is running 6.5 to 7.5 degrees more timing in the 240kpa row of the map. I'm using 8.4 pistons and pump 93 octane so I don't know how much room I have. I guess I should break out the electronic det cans and do some more testing. I won't until I check cam timing though.
I've got a lot more octane, but higher compression and for some reason this motor seems excessively ping-prone compared to my previous one.
The 165, 190, and 215 rows are dyno-tuned to MBT (yeah, weird, it wants more timing at 190 than it does at 165, I don't understand it but that's what the dyno says). The 240 row is slightly ping-limited, even on 100 octane, and the 265 row is heavily ping-limited. I think there'd be another 10-15 hp in it at 265 kpa if I had the octane.
Many of the japanese mufflers are not nearly proper 3" straight through because they are trying to comply with JASMA restrictions, many many hotdogs on high end japanese systems have incredible restrictions and go down to as little as 2.25", and are infact not hotdogs at all.
Dann
I have seen his muffler and I think that would be a generous term for it. It is definitely a minimum of 3".
I have seen his muffler and I think that would be a generous term for it. It is definitely a minimum of 3".
It is a 3in inlet but has a ricey 5in tip at the outlet. I'm not a fan of the look but this one seems to be pretty good build quality. I would prefer it to be hidden beneath the car but, meh. It was free to me and it isn't obnoxiously loud. I know it is straight through but I will verify I.D. throughout.
I got home late last night so I didn't get to look at the car any but I was thinking about ignition timing.
Many moons ago when Hustler was still posting bathhouse adventures he discussed IAT related timing retardation settings in megasquirt with a few members here. As a result of those discussions I made some changes to my settings waaaaay back then and never touched them again. I don't have logs of the pulls made on that mobile dyno at the track but, as Pdexta pointed out, it was pretty effing hot that day. Megasquirt was probably pulling timing like crazy with no decent airflow through the intercooler on a hot day on a mobile dyno in an asphalt parking lot. I'm attaching a screenshot of the settings but I am changing them to pull 1 degree every 70F degrees above 120F instead of every 7F degrees above 120F.
I will check everything else we discussed just to be prudent and will report back my findings.
Last edited by sixshooter; 09-09-2016 at 09:49 AM.
And, as the dyno shows, it would have been pulling timing as the boost went up. Funny thing is I think I made those changes prior to even having a turbo on the car. We're talking waaaay back. It's a total DERP on my part.
Yeah, it's important to try to normalize all of the dyno runs. The first few are going to be artificially high as the motor starts to heat soak, after that you want to pause in between each run to let the coolant temps and intake temps reach a standard starting point.
Random observation: one of the dyno operators I rented from was very impressed by my car's ability to cool back down in fairly short order with just his dyno fan blowing across it. TSE rad FTW! I guess he's used to drag race cars, rather than road course ones.
09-07-2016, 10:41 AM
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I guess he's used to drag race cars, rather than road course ones.
