4.5 litre v8 landcruiser VDJ70 VDJ79
Submitted: Saturday, Feb 22, 2025 at 11:57
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John H89
Can anyone tell me the air flow rate in m3/hour or liters per second (L/s) required for unrestricted air demand at maximum power of a 2020 4.5 litre v8 landcruiser VDJ79 engine ?
Reply By: RMD - Saturday, Feb 22, 2025 at 12:44
Saturday, Feb 22, 2025 at 12:44
John..
I takes TWO revolutions to complete one full engine cylinder cycle, ie, a FOUR STROKE ENGINE.
Each time your engine turns ONE revolution of the crankshaft it displaces 2.25 LITREs, 4 cylinders have operated, and if allowed to fill the cylinders perfectly it will ingest 2.25Litres of air, assuming no restrictions of throttle plate etc.
@1000rpm that means it is sucking in 2.25L x 1000 in one minute. Simple maths here.
Whatever the maximum power rpm is, eg, 2250rpm , it is 2.25 times the figure above. therefore, 2250litres of air @ 1000rpm , 2.25 M3. which is matched by injected fuel for each cylinder burn.
x 60mins for 1 hour of airflow.
Now, do you mean maximum POWER or MAXIMUM torque? They will be occurring at different rpm's, so not sure what to reply to there.
At 4000rpm it will be sucking 9000 litres of air , 9cu metres.
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647455
Follow Up By: kgarn - Saturday, Feb 22, 2025 at 13:15
Saturday, Feb 22, 2025 at 13:15
Yes, but what is the air flow at atmospheric pressure into the turbos(s) to produce the 9000 litres of compressed air to feed the cylinders ?
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Follow Up By: John H89 - Saturday, Feb 22, 2025 at 14:05
Saturday, Feb 22, 2025 at 14:05
Thanks you ??
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Follow Up By: RMD - Saturday, Feb 22, 2025 at 16:01
Saturday, Feb 22, 2025 at 16:01
kgarn
Turbos were not mentioned above.! So is it airflow rate in the Air box entry port? OR airflow rate into the turbos, the flow rate will be halved if considering two turbos, OR into each cylinder & depending on boost being developed at SAID RPM AND LOAD the ultimate pressure developed in the cylinder before valve closing will vary a lot. So read the BERNOULI principle of airflow through a stated hole size and some greater understanding of it all will be had! The calculations are manageable!
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Reply By: John H89 - Saturday, Feb 22, 2025 at 17:20
Saturday, Feb 22, 2025 at 17:20
My question is due to the fact that I am trying to choose air filter system that can deliver air to a 30 lb boost turbo upgrade.
I'm trying to calculate the air demands of a std engine with 15 psi factory turbo boost then the air demand for 30 psi.
Once I have the maxim demand at say 3000 rpm I can cross reference with the specification of air filter systems.
Thank you for your help ??
AnswerID:
647459
Follow Up By: RMD - Saturday, Feb 22, 2025 at 21:17
Saturday, Feb 22, 2025 at 21:17
John
Boyles law sort of explains if pressure is doubled then airflow to that container is doubled if temp remains the same. I would expect the airfilter to need to be able to cater for that doubling if negligible restriction is what you are after.
30PSI is getting up there!
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Reply By: Member - LeighW - Sunday, Feb 23, 2025 at 10:46
Sunday, Feb 23, 2025 at 10:46
I would assume you require this information for possibly fitted a prefilter? If so consult the manufacturer to see what filter they recommend.
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Reply By: Bob Y. - Qld - Sunday, Feb 23, 2025 at 17:48
Sunday, Feb 23, 2025 at 17:48
John,
Worth ringing some of the reputable diesel tuners, depending what state you’re in. Lot of them are now doing 30 psi plus tunes, with turbos like the G333, and not all have a modified air box.
Firms like Diesel Power Unlimited Qld, Tuneworks NSW, Power Torque VIC are just a few that have a good rep.
When I had my tune done, fitted an intercooler with 40% more efficiency, and they swapped out the
snorkel “hat” for a ram mount. Boost was set at 19 psi, the recommended peak for the factory unit.
Bob
AnswerID:
647468