I said please.
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Originally Posted by LownSlow616
(Post 1359094)
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 https://cimg6.ibsrv.net/gimg/www.mia...a4d7959ba1.jpg 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. |
I don't mind the extra discussion in this thread.
So, things it could be: 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. More boost, that will fix it. |
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. |
I see what you mean, it does kind of die off up top. How does the boost curve look, does it hold steady all the way to redline?
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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: http://www.codrus.com/dyno/synergy-O...mpare-190.png? --Ian |
3in pipe all the way back to a HKS Hi-Power straight through muffler (came with a car I parted out). We don't emissions test here.
Codrus, your hp graph continues to climb and mine gets stuffed. Please post details of your setup and timing map for comparison. |
Have you seen inside your muffler?
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 |
Originally Posted by sixshooter
(Post 1359321)
3in pipe all the way back to a HKS Hi-Power straight through muffler (came with a car I parted out). We don't emissions test here.
Codrus, your hp graph continues to climb and mine gets stuffed. Please post details of your setup and timing map for comparison. Spark table: http://www.codrus.com/miata/fm2r/Sep09-2016/timing.png? --Ian |
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.
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what size turbine housing on gtx28?
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Originally Posted by sixshooter
(Post 1359487)
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.
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. --Ian |
Originally Posted by nitrodann
(Post 1359328)
Have you seen inside your muffler?
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 |
Originally Posted by LownSlow616
(Post 1359499)
what size turbine housing on gtx28?
Originally Posted by Ryan_G
(Post 1359504)
I have seen his muffler and I think that would be a generous term for it. It is definitely a minimum of 3".
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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. |
lol it must have been running near 0* hahahah
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Originally Posted by 18psi
(Post 1359730)
lol it must have been running near 0* hahahah
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Same thing happened with Eds car on the dyno. I missed the coolant temp corrections. Ran like 1* of timing.
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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. --Ian |
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