5M & 7M Volumetric Efficiency
- Thread starter Supra5MGTE
- Start date
VE that is unknown.
I can tell you it is MIGHT be north of 80% on an N/A but a turbo goes down in VE.
I can tell you it is MIGHT be north of 80% on an N/A but a turbo goes down in VE.
figgie said:
Well I need the engine's NA VE for formulas. Garrett's site is so awsome for helping picking a turbo. turbo 103 is great! they said 2 valve late model engines are 88%-95% and newer 4valve motors are 95-99% VE. So I used 85% in my calculations. I'm looking at 21psi, 2.4 air ratio, and 33-50lb/min of air under boost band. and that'd give me 500 crank hp @ 6,700rpm. I'm making data tables for quick reference for my set up, from 8-30psi and 400HP-600HP. this way I can easily read a turbo map.
only way to get ve is to put the motor alone on a break dyno. PERIOD. Anything else is guessing.
btw 4 valve motors might have that high a VE but add a turbo and the VE willd rop significantly.
btw 4 valve motors might have that high a VE but add a turbo and the VE willd rop significantly.
figgie said:
right, but the formula Garrett is using says to use the regular N/A VE. 80-95& is pretty typical b/c when I was in the V8 small block world and into cylinder head designs and stuff. I remember most performance 350's with ported, aftermarket large valve aluminum heads were around 90% my stock TPI i think was 80%ish or low 80's.
????
A turbo increases volumetric efficiency. A turbo charger increases the amount of energy produced(efficiency) per liter(volume).
Also are you wondering about an NA engine with(7mge) or without(7mgte) the ACIS system. As the ACIS system can considerably increase VE on an NA engine. BMW even produced a similar acoustic system that achieved over 100% VE
Similarly do you want the VE of a 7mge engine or the VE of a 7mgte engine in NA form? As the change in compression ratio will also change the VE.
A turbo increases volumetric efficiency. A turbo charger increases the amount of energy produced(efficiency) per liter(volume).
Also are you wondering about an NA engine with(7mge) or without(7mgte) the ACIS system. As the ACIS system can considerably increase VE on an NA engine. BMW even produced a similar acoustic system that achieved over 100% VE
Similarly do you want the VE of a 7mge engine or the VE of a 7mgte engine in NA form? As the change in compression ratio will also change the VE.
i'm looking for the VE of the 5MGE to be honest. I figured if the 7m's were roughly say 90% my 5M would be 85%. just making sure i'm not overshooting the 5M's VE.
85% is a good estimated Volumetric Efficiency. Being a 4 valve head you might hit 88%. But I would stay conservative and go with 85%
dirgle said:
That's what I figured. 85% was about right. and I figure if the old Chebby 350's were about 80% ... (and people did put those on the engine dyno's and do work with them) our DOHC Jap motor must bit a bit higher.
dirgle said:
only when under boost
it actually lowers the VE when off boost that when averaged LOWERS the VE of the engine figgie said:only when under boost
but when you're calculating HP targets and such, you're under boost. I'm sure Garrett knows what they are doing when say say use the VE of the engine itself... NA. I don't care if it lower my 3,000rpm 10% throttle HP. I care about 6,700rpm and 100% throttle and under boost.
Supra5MGTE said:
well then with that train off thought, do not EVER get into standalone because you honestly do not know how VE works. VE is overall not just 100%/WOT.
figgie said:
really... I thought It was under WOT. hhhmmmm I don't know... i'm using 85%. I was just wondering if people knew the "exact" % toyota put on them. Oh well, guess it's one of those things that's not exactly a spec.
figgie said:only when under boost
The turbocharger only hinders the VE when the throttle is at WOT and only for the first part of the RPM Band 600~1800 RPM give or take a few hundred. If the throttle is at any point other than WOT it (the throttle) becomes the greatest obstruction in VE.
If the throttle is at WOT, the turbo is only in the way until it achieves enough momentum to no longer hinder the air flow. This does not mean the point where the turbo produces boost but where it is spinning fast enough to not get in the way. This point is about 1800 RPM’s give or take depending upon your turbo.
Even at this point the engine cannot produce it’s peak VE. It is still down around 30%-50% VE. Generally, the RPM at peak VE coincides with the RPM at the torque peak. So peak VE is still a little ways up the RPM band. So the turbo does not hinder peak VE.
However it looks like your talking about average VE. In which case even a N/A engine only has an average VE of about 60% on a good day. The modern gasoline engine only has a small window for peak VE A smart tuner will adjust his engine components to operate around this point to get the most usable engine performance.
Good tuners don’t care about average VE they want to know what the peak VE is and where in the RPM band it produces it. Then they can adjust for it.
well on Garrett's site they said the peak Torque rpm is usually the lowest rpm you'll see "full boost". say 4,500rpm is the peak torque curve... I guess they're saying I'll be boosting (full boost) between 4,500-shift point. that's probly why they're saying use 88% for 2 valve engines and 95% for 4 valve new engines I guess. I don't know... this topic sure has made me think.