pcmhacking.net

yeah the main issue with logging pressure sensors is logging speed. 7000 rpm means at 100hz logging speed you would get less than one sample per engine revolution. to get at least one sample per engine degree, you would need to log at about 42000hz. thats not something you can knock up easily with an arduino lol.

I dunno, most audio receivers will sample at 48khz or more, and so it could be done with the right front end to handle the voltage range of the sensor. But you would need a sensor able to react fast enough it would take a hammering going from extreme to extreme at those speeds.

interesting without intake pipe we reduced the restriction slightly (Kpa went up by about 1.5 Kpa) as that was what we were testing for but power was hurt big time. But still in either case there was a Kpa drop with rpm hence why we need dual TB. Single is choking the engine.

you don't really need to test out resonances with sensors and such and test benches.

All you need to do is understand the physics on how an engine works, fluid wise no mechanically and apply well know maths to the problem. Verify the maths against know engines and dyno results and from there you can calculate the engine design from all aspects including intake. And then its just fine tuning on the dyno by varying lengths of the runners and ram tube. You can do the same with exhaust but its harder so just rely on maths and experience of engine builders in motor sports rather than street engine builders as they do more research and strive harder to get results.

BennVenn wrote:

vlad01 wrote:we have no bell mouth in either case of pipe or TB, the TB actually is machined radius on the inside. Pipe length played 99% of the effects. It didn't care of bellows, turns, filter no filter, bits of pipe held by hand end to end, fingers over the end of the pipe. No of that effected. Added 400mm of pipe and power and torque went up everywhere.

We tested this for most of the day, dyno run after run and backed up the results. No doubt what was going on. And how many engine builders/tuner have worked this out? probably 2/5th of bugger all.

Only car makers take this into consideration and know what they are doing.

What was the effect of more than 400mm?

bit over 5Nm I recall. That was 400mm additional length to 800mm long intake. So was about 1200mm long and that was the best result but we were out of pipe to keep adding length. But I didn't try super short lengths either so it might of dropped power as I shorten and then regain again at a certain length. I predict this to happen and will test next time. Intake harmonics.

BennVenn wrote:Not sure. How much Hp does it take to spin an engine up to 7000rpm?

entirely depends on engine design.

No. of cyl, bore size, rod length, oiling,valve train, bearings, piston and ring configuration, pumping losses blah blah list goes on.

for example my virtual engine design for a race v6. 98hp loss at 7000 and 16hp pumping losses. that's at 80% mechanical efficiency

Not sure what this one is, but looks similar to Biggvl's
http://www.gumtree.com.au/s-ad/cessnock ... 1106355863

yoda69 wrote:Not sure what this one is, but looks similar to Biggvl's
http://www.gumtree.com.au/s-ad/cessnock ... 1106355863

Looks like the MACE twin TB. He supplied them for a few years but it was a slow moving item and I believe tuning for them was an issue (not many people tuning V6's before this website became popular) so they stopped been produced.

Jayme wrote:yeah the main issue with logging pressure sensors is logging speed. 7000 rpm means at 100hz logging speed you would get less than one sample per engine revolution. to get at least one sample per engine degree, you would need to log at about 42000hz. thats not something you can knock up easily with an arduino lol.

I can build the hardware to sample @ 1mhz and feed it back to your pc via USB. That is not a problem. Can even do all the peak detection in the micro. Could do peak with a sample and hold opamp circuit so we're only dealing with 1 event per compression stroke. Arduino territory.

Whats a typical cylinder pressure on a NA motor? 150psi? Im sure fast response sensors for this range exist.

There are many things individual cylinder pressure will tell you that static flow testing wont. Things like intake volume, volume distribution throughout the path, effect of port velocities etc...

Im almost certain with that manifold posted earlier not all cylinders are getting the same air charge.

Which raises the question, why did they settle on the bellmouth shape they did? Flow distribution?

What is the firing order?

Unfortunately peak pressure changes depending on ignition timing so you would need to be able to log multiple points in one cycle depending on engine load, rpm etc.

Cranking pressure on a decent (stock) ecotec is ~170psi, during a combustion stroke it would be much higher.

Firing order, 1 6 5 4 3 2

So basically it's each runner in order....

MY understanding is that a split plenum manifold is the best design. Walker did one but it was bloody expensive and only a few were ever produced.

Whats a typical cylinder pressure on a NA motor? 150psi?

max cylinder pressure on my na v12 vary from 600 psi at idle to 1100 psi at 6500 rpm
10.6:1 static comp ratio