Turbo Plenum Spacer Group Buy - Page 11 - LotusTalk - The Lotus Cars Community
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post #201 of 211 (permalink) Old 01-22-2019, 10:38 AM
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Okay. I’m in. PM me if you would like to go over the details.

JG
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post #202 of 211 (permalink) Old 01-22-2019, 10:20 PM
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Okay. I’m in. PM me if you would like to go over the details.

JG

We would need a minimum of 7 to 8 more people for this to happen.
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post #203 of 211 (permalink) Old 02-07-2019, 07:51 PM
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Originally Posted by pete inno View Post
I asked this question as well a while ago and no one gave me an answer. I assume it adds a shiny part to the intake and that is about it.
Pete, please see attachment. Many smart people have researched this phenomenon, see biblography, attached.

Regarding the spacer thickness, there's an interesting photo on page 48 of Corky Bell's book "Maximum Boost" that shows a plenum spacer on a Esprit that's about 3"+.
Bob,
Good eye!
That spacer is huuuge! I'd say, it is thicker than the cover (3.5" OD), so it must be 4" thick. Book does not mention the spacer at all. This makes me think that Corky used someone's else picture. I'm wondering whose car it might have been? It was a long time ago, because this book was first printed in 1997.

85-88 cars are limited to 1-1.5" spacer thickness, because of the plenum cover proximity to the air filter box. Additional 0.5-0.75" of clearance can be gained by grinding off 3/4" of the flange (@ top of the "beak") of the air filter cover.

89+ cars have much more room available.
Personally, I'd like to go bigger.
I'm wondering if you would make me 2" thick part. CNC water jet program operates in x-y plane. There is no Z component, so thickens of the plate should not make any difference.
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post #204 of 211 (permalink) Old 02-09-2019, 06:22 AM
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@Pete
Here is an interesting tidbit from SAE Paper 2008-01-3007

ABSTRACT Intake tuning is a widely recognized method for optimizing the performance of a naturally aspirated engine for motorsports applications. Wave resonance and Helmholtz theories are useful for predicting the impact of intake runner length on engine performance. However, there is very little information in the literature regarding the effects of intake plenum volume. The goal of this study was to determine the effects of intake plenum volume on engine performance for a restricted naturally aspirated engine for Formula SAE (FSAE) vehicle use. Testing was conducted on a four cylinder 600 cc motorcycle engine fitted with a 20 mm restrictor in compliance with FSAE competition rules. Plenum sizes were varied from 2 to 10 times engine displacement (1.2 to 6.0 L) and engine speeds were varied from 3,000 to 12,500 RPM. Performance metrics including volumetric efficiency, torque and power were recorded at steady state conditions. Experimental results showed that engine performance increased modestly as plenum volume was increased from 2 to 8 times engine displacement. Increasing plenum volume beyond 8 times engine displacement resulted in significant improvement in performance parameters. Overall, peak HP was shown to increase from 54 kW to 63 kW over the range of plenums tested. While it was clear that larger intake plenums yielded better steady state performance, their effect on transient performance was not explored and will be the subject of further research.


Also results of an empirical study has showed that the variation in plenum volume causes an improvement of the engine performance and the pollutant emissions.
Energy Conversion and Management
Volume 48, Issue 3, March 2007, Pages 961–966

Also, see https://www.slideshare.net/gm8655/intake-plenum-volume,

http://planetsoarer.com/resonator/Re...rsAcoustic.htm

and here

http://gasturbinespower.asmedigitalc...icleid=1425888

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post #205 of 211 (permalink) Old 02-09-2019, 10:05 AM
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Thanks Mr. Danger, food for thought. Looks like the plenum spacer would have to be quite a bit thicker to see (and feel) any significant results. Pardon my ignorance but it appears these studies are on normally aspirated engines. What variations does the turbo throw into this formula?
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post #206 of 211 (permalink) Old 02-10-2019, 05:45 AM
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Quote:
Originally Posted by pete inno View Post
Thanks Mr. Danger, food for thought. Looks like the plenum spacer would have to be quite a bit thicker to see (and feel) any significant results. Pardon my ignorance but it appears these studies are on normally aspirated engines. What variations does the turbo throw into this formula?
Turbocharged engine still benefits from a tuned intake. After all, it's the same engine/principles, but operating under pressure. Tuned IM does give the engine an opportunity to wind up the boost more effectively.

BEST PRACTICES: with short runners, 2-3x engine displacement for all out power, 1.5-2x displacement for mixed response/power, and .75-1.5x displacement for throttle response demanding setups (autox type stuff). More voleme = worse throttle response but more top end power
OEM set up has 1.06x ratio.
.
Generally, a plenum volume of approximately 80% of engine capacity for naturally aspirated engines and 150% of engine capacity for turbocharged engines works best.

But I have seen as much as 220% of engine volume used in high hp / high boost turbocharged applications.

P.S. Another benefit of fitting a spacer: plenum back cover wall moves away from the inlet bell-mouths creating larger gap, which enables air to enter runner throats at a better angle.
Thus, Loren's ultimate plenum volume= 3.5 liter and bell mouth-to-back cover spacing measures ~ 4". OE measures only 2.4".
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post #207 of 211 (permalink) Old 04-11-2019, 06:43 AM
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post #208 of 211 (permalink) Old 04-11-2019, 07:11 AM
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There is a group buy on TLF again.
I am in!
https://www.thelotusforums.com/forum...spacer-by-pnm/
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post #209 of 211 (permalink) Old 06-06-2019, 08:46 AM
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PNM Spacer

Hi Guys, I'm new here , just an update PNM are taking pre orders on the spacer on TLF as PAN has stated
https://www.lotustalk.com/forums/att...mentid=1232556
https://www.lotustalk.com/forums/att...mentid=1232558

I still have some 15% discount codes to distribute if anyone is interested.
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post #210 of 211 (permalink) Old 06-18-2019, 07:11 AM
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it looks much better than the previous one and with all fitting kits
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post #211 of 211 (permalink) Old 06-18-2019, 07:49 PM
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Welcome to Lotus Talk Mark, and thanks for all you've done for the Alunox buy etc over on TLF
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