I don't think the issue is would there be an improvement but is the improvement worth the cash spent. low end builds I believe it's probably not but for a full on race engine that's trying t squeeze every bit of power most definitely. the big question is where does it cross from uneconomical gain to viable work
Yes it does, same for any motor. A modern quad cam will be pretty damn good as is, circa 95%, and after a good port u reportedly you'll get close to 100 (100 being impossible).
I think there's a couple of different setups/tests/definitions for VE or something, with tuned runners and stuff modern engines do apparently go over 100 without boost, no air ram or anything just the inertia of the air charge.
S2000 Flow tested over 109% VE OEM form, reason why it makes over 100HP per liter. Our local Engineering Institute similar to MIT in Boston. Page 18 in the PDF. http://www.wpi.edu/Pubs/E-project/Available/E-project-043009-120942/unrestricted/Engine_Hydrolock_Mitigation.pdf
So how do you go about calculating the VE ? If I'm making 3 times the power of stock from 100hp per litre to now 300hp per litre ? .
Its hard to calculate as there are so many factors. to name a few - intake air temp - intake air velocity - engine displacement - cfm - current rpm - bore length - bore diameter - head gasket thickness - head gasket diameter - bowl to deck volume it becomes a basic calculation once all these factors are considered. But also saying that, VE may be 100% at 5000rpm and 110% at 6000rpm because of the way the engine breaths. Turbo pushing harder, more fuel, more heat(clearances can very by fractions giving a tighter seal). VE is only theoretical to the engine, what we actually see in terms of scan tool data may be completely different. http://www.ajdesigner.com/phpengine/engine_equations_volumetric_efficiency.php Is an online theoretical VE calculator. Just throw in your numbers, and it will give you as close to perfect world data as you can get. Without doing the massive calculation that would be involved to more precise engine specs, this is as close as it gets.
Yep exactly.Its approaching a black art to calculate accurately and repeatedly! OP's question, ANY change in airflow in/out of the engine will change VE on a given engine. E
Hey Rob VE/volumetric efficiency can be calc'd out. There's a good article here http://www.installuniversity.com/in...metric_efficiency/ve_computation_9.012000.htm
How does a normally aspirated engine displaced more than 100% of capacity? Haven't read the PDF I'm on my phone so not really practical to read...
Because that will be air capacity at standard conditions (1 bar and 20degC or other standard starting figures). Increase the pressure of the air and you will get more volume. Pressure reversion and all that.
Sort of been touched on above but Black Beast, VE is generally measured for the engine alone without boost so the S2000's feat is pretty impressive for a production car. If you include the turbos in the system then yeah the VE is amplified massively giving 200% + pretty simply. The efficiency of the engine alone will change with charge density still so if you're engineering a boosted you would want to test it at the boosted pressure too. Stumagoo, your bike also revs 3-8krpm higher than the S2000 (depending on bike) so that plays a role in the higher peak power. Bikes do tend to have very well tuned heads though so I wouldn't be surprised if it's over 100% peak too. ZEDZY the figures you get from the ECU aren't really related to test bench figures, they're more of a relative figure used in selecting load cells so like dyno HP figures comparing them wont be super enlightening. Rob, exhaust scavenging and port tuning can allow you to give the incoming charge such inertia that it over fills the cylinder, need to time the valves just right so it doesn't escape again though. VE is much more popular in simple atmo designs and carbed motors as it's more relevant there and one of the few things you can really accurately tune in an old V8 since timing and fuel control rely on physical cues. For the majority of us here why spend all the time getting a 10% improvement in head flow when you can just add X% more boost?
Because of efficiency ? I judge flow (efficiency) by the amount of boost you have to run for a given hp And my heads flow a sh#t load more than 10% . .
It definitely helps but your build is way in the minority and already tapped out gains from boost alone, head and manifold porting probably wouldn't be in your first couple of sentences if a friend bought a stock Z and wanted to start adding power. In GM and Ford circles getting an Edelbrock manifold is often one of the first mods because that's where the best gains are.
This is what I was getting at, for the majority of us Z owners porting Oversize valves and other head work is a diminshing return on investment for power, money is better spent on bigger turbos injectors tune etc, however once all those are done and squeezed to the max headwork is vital to get the extra power one may be chasing, I would add the OP refers to a fully built engine which to me suggests that something like Blackbeasts build or Rob260's is in mind and then headwork is preferred for me running my stock manual turbos on 12psi with stock injectors I would never see the bonus of this sort of work.
Well the OP was asking about the heads. personally I would firstly Do all breather mods Secondly turbo upgrade . Then motor after you blow it As far as engine VE , I would like to put a stock long block into my setup and pump 22psi into it and see what it makes . It would struggle to get 400rwkw compared to the 500rwkw my engine is doing. On the flip side if you put anything from stock turbos to Gtt3071r's in my car ,it would spool quicker and make the most top end for said turbos than any other setup . .
