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Looking for G25-550/660 data on any miata engine, especially 2.5L
Hello there,
so, I'm looking for any data for G25-550/660 on miata engine, especially 2.5L. I'm building two engines for high power application and I'm trying to decide if 550 will spool fast enough on 1.8 VVT, and if I should go for 550 or 660 for 2.5L NC.
Thanks!
I've been in the same boat for a long time. Only reputable information I've been able to gather that is somewhat applicable to us is this page/video using an SR20. Outside of that Greg Peters from car passion channel just recently helped tune RileySlides built KA24 running a 550. He made ~450whp on ethanol. I commented on Greg's post on Insta and asked about what it'd make on pump and he doesn't think the 550 can make 400whp on pump gas. I didn't see any spool data, but you might be able to dm either of them on instagram. Greg's post is in his last 10-15 on instagram as of right now so it shouldn't be to hard for you to find. Lastly there was one person (Nbboy_) who claimed to have the g25-550 on their miata, but due to tuning complications never got to post some data for us. Heres what he said:
Originally Posted by Nbboy_
quality of turbo is pretty damn good, all lines and fittings seem to be holding up well.
engine is a 1.9l forged bottom, with cams, springs, retainers, all the jazz. Only thing that wasn’t touched was crank and main caps.
with the g25/550 it comes on kind of late(3400+) but pulls HARDDD. Ive gone to dyno twice so far and have been having some issues and only been able to get up to 9psi and it was making 223. I believe my injectors could be clogged from me making new AN lines so ima clean then and go back and turn the boost up to 18-20 psi and be in the mid 3s. Definitely would recommend the g25 and kraken kit as a whole.
If only shuiend could post some data from his pulsar turbo...
Just had mine mapped today with a G25-550, the graph is flywheel HP so knock off around 30hp for wheel HP.
Two maps shown - the lower one is 0.8bar and the higher one 1.1bar. Tuner said it was flowing great and has huge potential to go a lot higher. A video of the run is here https://fb.watch/ll8HdZeX6s/
Last edited by Corsaro; 06-23-2023 at 07:03 AM.
Reason: typo
Can we get more details on this build; looks like a BP in the video? A BP with 300whp at 0.8bar/11.6psi on something that spools before 4krpm is thought provoking.
Sure -
re-bored to 1.9l, CP Pistons, Manley Rods, ARP studs.
VVT block, Euro flat top intake, Ported & polished 99 head, Supertech intake/exhaust valves & valve springs, Catcam turbo cam & pulleys, ATI damper.
Walton exhaust manifold with Turbosmart 45 external wastegate to a custom 3-inch exhaust.
I just gave an outline spec the place that built the engine (a forged G25-550 build, capable of 450hp but initially detuned to 350hp) and don't yet have all the lower level detail of exactly what parts they fitted. I am picking the car up from the builder next week, where I hope to have all the exact part specifications they fitted.
Just had mine mapped today with a G25-550, the graph is flywheel HP so knock off around 30hp for wheel HP.
Two maps shown - the lower one is 0.8bar and the higher one 1.1bar. Tuner said it was flowing great and has huge potential to go a lot higher. A video of the run is here https://fb.watch/ll8HdZeX6s/
Shoot 4F on DD rollers is usually an 18% factor going from wheels to engine hp estimation, so 362hp fly estimation probably recorded 307hp wheel. DD wheel figures can feel cruel.
Just had mine mapped today with a G25-550, the graph is flywheel HP so knock off around 30hp for wheel HP.
Two maps shown - the lower one is 0.8bar and the higher one 1.1bar. Tuner said it was flowing great and has huge potential to go a lot higher. A video of the run is here https://fb.watch/ll8HdZeX6s/
Any pics of the manifold? Interesting setup! The Walton tubulars look nice, though am always concerned with longevity vs cast.
Also, any particular reason for only going to 6300rpm? Power is still climbing!
Could you please take a log in the 1:1 gear from full throttle at say 2000rpm until the boost levels out? The dyno ramp seemed fairly quick so it's tricky to compare to other turbos.
Which gearbox are you running? 350ftlb is a lot!
Last edited by Tran; 07-26-2023 at 07:23 AM.
Reason: Added gearbox question
Sorry but only this for now - It was a work of art before fitting, I think the website has an image of an unfitted one. They have a lifetime guarantee and look top notch quality so time will tell.
Regards rpm - the limit is 7300, for some reason the scale isn't correct on the graph. It's back to fine tune the map in around a month I'll try and get a better plot then.
Running a 6-speed with 3.6 diff. Trying to be mechanically sympathetic and not smash gears or doing 0-60's, but yes that is a weak point. Maybe a bmw box swap when funds allow, I am not to fussed on the 6-speed, the 5/6 gate isn't the smoothest (at least on mine).
05-27-2023, 05:57 PM
Looking for G25-550/660 data on any miata engine, especially 2.5L
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