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The "other" spool question
When driving around on the road, initial spool, i.E. at what rpm does boost really kick in, when in a higher gear, is the most important. This is the question that the "I want your spool data" thread is trying to answer.
But when on the track (not autocross) you're usually always within the right rpm band for your turbo to reach full boost. Here the question is how long does it take to spool up under these conditions. Interesting to me is: at 5000 rpm, in 3rd or 4th, how long does it take coming off 0% tps from full throttle to full boost? Suggested parameters: consider the turbo fully spooled at 5kpa below boost target. Consider full throttle to be 95% throttle. Under these conditions, my trusty old T28 needs between 400ms and 500ms. That's without boost control enabled, since I currently run of the WG on the track. Car: 99 Total Weight: 2750lbs (estimated) Gear: 4th of 5 Turbo setup: - Mystery T28 (Garrett) - Begi cast manifold - Old style FM downpipe - Old style FM IC - Enthuza 3" exhaust with cat-delete - MS3X - target MAP: 172 Measurements Start rpm: 4863 Spooled rpm: 5088 MAP at spooled rpm: 167.7 Spool time: 442ms Starting at 4krpm, the spool time goes up to a full second! It does feel a bit laggy. Is a 2560R faster? How about the EFR 6258? Anybody willing to share data? |
I think the more helpful way to discuss it is "boost threshold" vs "spool"
for whatever it's worth, yes a proper gt2560r will do it way better than the begi chinacharger and for whatever else it's worth, the efr6258 I'm tuning now crosses into boost with the touch of the throttle. Like almost exactly as fast as you touch the pedal. I'll see if I can get a log. It's bananas. I don't think I can even have it pulling vaccum at part throttle past 4k in 4th, it will be at 110kpa already |
Wow, the efr is that fast?
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To give you an idea: as soon as I step on it in at 2000 rpm, it goes up to 3-4psi. Instantly
And then starts building from there. When you drive it in the upper rpm range, it feels like an N/A car. |
Originally Posted by stefanst
(Post 1268096)
When driving around on the road, initial spool, i.E. at what rpm does boost really kick in, when in a higher gear, is the most important. This is the question that the "I want your spool data" thread is trying to answer.
But when on the track (not autocross) you're usually always within the right rpm band for your turbo to reach full boost. Here the question is how long does it take to spool up under these conditions. Interesting to me is: at 5000 rpm, in 3rd or 4th, how long does it take coming off 0% tps from full throttle to full boost? Suggested parameters: consider the turbo fully spooled at 5kpa below boost target. Consider full throttle to be 95% throttle. Under these conditions, my trusty old T28 needs between 400ms and 500ms. That's without boost control enabled, since I currently run of the WG on the track. Car: 99 Total Weight: 2750lbs (estimated) Gear: 4th of 5 Turbo setup: - Mystery T28 (Garrett) - Begi cast manifold - Old style FM downpipe - Old style FM IC - Enthuza 3" exhaust with cat-delete - MS3X - target MAP: 172 Measurements Start rpm: 4863 Spooled rpm: 5088 MAP at spooled rpm: 167.7 Spool time: 442ms Starting at 4krpm, the spool time goes up to a full second! It does feel a bit laggy. Is a 2560R faster? How about the EFR 6258? Anybody willing to share data? My GT3271 setup was just under 500ms if I was above 6,000 RPMs (rev'd that motor to 8) If it was at 5,000 it was probably more like 700ms, still very fast but not instant. I did a similar test with the whipple, it will go from full vacuum, to full boost in under 200ms. I'm sure some turbo folks will post that their setup is faster to boost/it's instant/there's no lag at all. |
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Originally Posted by 18psi
(Post 1268154)
To give you an idea: as soon as I step on it in at 2000 rpm, it goes up to 3-4psi. Instantly And then starts building from there. When you drive it in the upper rpm range, it feels like an N/A car.
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Yeah once you're fully north of 4k in my car its just a big cube motor, the time the turbo takes to make all the power is pushing the edge of human perception.
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With a T28, you should have zero difficulties with spool at any RPM. That's a tiny turbo and 8 psi is a very modest boost target. If I can instantly spin T3/T04B/E turbos to 18 psi with no problem above 4-5000 rpm, there is no way you should be having any difficulty with a T28 at 8 psi. You're running a smaller turbine and a smaller compressor wheel and you're aiming for less boost on the same basic motor as me. Your exhaust setup is very similar to mine, just with a smaller diameter DP.
On the track I think you will pretty much never fall out of boost unless you close the throttle and then you'll be back into it the second you crack it open. |
Originally Posted by DNMakinson
(Post 1268188)
<p></p><p>I think that is a little different from what OP is suggesting. He starts at closed throttle, not steady speed. </p>
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Originally Posted by AlwaysBroken
(Post 1268196)
With a T28, you should have zero difficulties with spool at any RPM. That's a tiny turbo and 8 psi is a very modest boost target. If I can instantly spin T3/T04B/E turbos to 18 psi with no problem above 4-5000 rpm, there is no way you should be having any difficulty with a T28 at 8 psi. You're running a smaller turbine and a smaller compressor wheel and you're aiming for less boost on the same basic motor as me. Your exhaust setup is very similar to mine, just with a smaller diameter DP.
On the track I think you will pretty much never fall out of boost unless you close the throttle and then you'll be back into it the second you crack it open. Some of them spool worse than a genuine Garrett 30 |
OP, can you post your compressor/turbine wheel exducer/inducer diameters?
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Originally Posted by 18psi
(Post 1268203)
have you ever actually tried a China t28?
Some of them spool worse than a genuine Garrett 30 |
<p> </p><p> </p><p>Actually, on my car, the difference(0-TPS vs Cruise punch) is imperceptible as well, but not so impressive.</p><p>I made 3 runs.0 TPS, then level cruise, then slight uphill cruise. Also, done at 4K, rather than 5K. Here are the results:</p><p>Start TPS: 0 Start RPM: 3910 Start kPa:15 Jumped to 92kPa m Finish RPM: 4110 Finish kPa: 149 Time: 750 mS</p><p>Start TPS: 6.3 Start RPM: 3690 Start kPa:31 Jumped to 93kPa Finish RPM: 3880 Finish kPa: 148 Time: 750 mS</p><p>Start TPS: 12.4 Start RPM: 3950 Start kPa:51 Jumped to 72kPa Finish RPM: 4110 Finish kPa: 148 Time: 560 mS</p><p><img src="http://cimg3.ibsrv.net/gimg/www.miataturbo.net-vbulletin/1125x605/80-0tps_a06f2ce5f0cc4a659235f67b7f999500c25b8d9b.png" title="" /><img src="https://cimg4.ibsrv.net/gimg/www.miataturbo.net-vbulletin/1125x605/80-easy_cruise_0698d7eb7805e84d02e5b01aca98c9c4f71a09 c3.png" title="" /><img src="https://cimg5.ibsrv.net/gimg/www.miataturbo.net-vbulletin/1125x605/80-slight_uphill_b804d9e8dc10f262cf9ca1889f94673978d5 201a.png" title="" /> </p><p> </p><p> </p>
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That's some great info so far. Thanks!
I have been toying with the 6258 idea for quite a while now.... About my turbo: It's the T28 that came with the FMII kit in 1999 when the car was new. That's the last time I had it off the manifold. I called it a 'mystery' T28, because I know nothing else about it. And I'm not taking it off to measure bits. Once it's off, it's not going back on! When I'm at part throttle, with the turbo spinning, but pressure in the intake below 100kpa, response is actually pretty good. Depending on MAP and RPM, it is often almost instantaneous. But shifting just kills it. This is why I asked about the response when going from 0% TPS to 100% TPS at rpm. |
Originally Posted by stefanst
(Post 1268336)
That's some great info so far. Thanks!
I have been toying with the 6258 idea for quite a while now.... About my turbo: It's the T28 that came with the FMII kit in 1999 when the car was new. That's the last time I had it off the manifold. I called it a 'mystery' T28, because I know nothing else about it. And I'm not taking it off to measure bits. Once it's off, it's not going back on! When I'm at part throttle, with the turbo spinning, but pressure in the intake below 100kpa, response is actually pretty good. Depending on MAP and RPM, it is often almost instantaneous. But shifting just kills it. This is why I asked about the response when going from 0% TPS to 100% TPS at rpm. |
Originally Posted by AlwaysBroken
(Post 1268205)
He said it was garrett. I have no experience with chinachargers. Chinachargers weren't even a thing when I put my setup together.
Anyway, I just did it with the EFR and at 4k going from vacuum to 9psi took 160ms. :D To reach 16psi took about 500ms, but that's with a janky gate and bleed type-mbc. Basically crap. Tomorrow I should be getting the proper gate and a 3port mac valve to install. I'll post logs tomorrow if I don't forget. |
It's supposedly not a gt2560r. This kit is soooo ancient they did some other Garrett T28 back then. I sent them an email to ask specifics a few years back and all they could say is T28, no further info available. But they seemed pretty certain that it's a journal bearing.
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<p>
Originally Posted by 18psi
(Post 1268364)
Anyway, I just did it with the EFR and at 4k going from vacuum to 9psi took 160ms. <img alt="" src="images/smilies/biggrin.gif" title="big grin" /></p><p>To reach 16psi took about 500ms, but that's with a janky gate and bleed type-mbc. Basically crap. Tomorrow I should be getting the proper gate and a 3port mac valve to install.
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1 Attachment(s)
Ok re-ran last night's log, not quite as good as I said but still really good.
And again, this is on terrible boost control. EBC still hasn't shown up in the mail yet. https://www.miataturbo.net/attachmen...ine=1442855530 132ms from vacuum to 6psi :party: |
The parameters being measured here are highly dependent upon Accelerator Enrichment settings. The data may be empirical but the variables are not isolated.
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