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Posted:
Thu May 07, 2009 1:35 am
by jsa
Posted:
Thu May 07, 2009 11:25 am
by 200cfm
Thanks jsa for the clarification. I am starting to understand this better. It does look like some extra filling is occuring prior to the intake valve closing (IC) point on the 5500 graph. Appears to be peaking at 36 psi. That must be the turbo pressure continuing to fill the chamber beyond BDC. And I see that the timing port pulse for the intake valve opening (IO) is only slightly moving up and then bleeds off quickly as the valve moves further off the seat. This is really a nice software progam.
Posted:
Thu May 07, 2009 1:29 pm
by jfholm
[color=#000000]Good description by John (jsa) on what is happening. I have included a screen shot below to help visualize that very thing. The peak of the dip is at 600
Posted:
Thu May 07, 2009 1:33 pm
by jfholm
Now here is a screen shot at 5500 rpm, Notice the dip?
John
Posted:
Thu May 07, 2009 2:00 pm
by jfholm
Now just to give a little comparison, I have included two shots of my SBC which is naturally aspirated. I put the first on at 4000 rpm peak TQ and the second at 6000 rpm peak HP
John
Posted:
Thu May 07, 2009 7:41 pm
by jsa
Posted:
Thu May 07, 2009 8:27 pm
by slracer
The Lotus package used to be offered in a single cylinder variant as a FREE download. Don't know if it is still there or that was a promo? If that would help, worth checking.
Doug
Posted:
Thu May 07, 2009 8:50 pm
by emarsh
Posted:
Thu May 07, 2009 9:55 pm
by jsa
Yes Doug the single version is available free.
emarsh,
For ITB's I imagine it would be useful for the inlet side. Similarly open single pipes on the exhaust. Still a good learning tool but too limited for more complex manifolding.
Posted:
Thu May 07, 2009 10:15 pm
by emarsh
Posted:
Tue May 26, 2009 3:47 pm
by jfholm
NICE! Great pictures Tom.
Here is a current good discussion on turbos over at speedtalk
John
Posted:
Tue May 26, 2009 10:30 pm
by 200cfm
Interesting! My system is using factory manifolds which would be "log type" design. I don't have individual runners to the turbo. And my heads have simezze ports for 3/5 and 4/6 exhaust. The stude exhaust port exit is square and not round. And the mating of the exhaust manifold along with the inside turns are also square and not round. But in one section the square casting converges into a trianglar shape which has to be "choke" point. Judging from the topic the design is not optimum. However Barnhouse states that a square tubing turn is superior to a round tubing turn. If that is so, then putting individual header tubings to my turbo might be introducing losses that the square manifold exit and turns don't have to contend with.
I'll see if I can post up a photo of the current exhausting plumbing. It's crude but it seems to work fine.
Posted:
Tue May 26, 2009 11:58 pm
by jfholm
besides your car goes fast enough to make me pee. I just thought it was interesting. Sometimes the people forget where "real" hot rodding starts and stops and just keep throwing bushel baskets of hundred dollar bills at it.
If I can find the pictures I will also post the ones I had of "square" tubing headers. Yes, they were built just like regular tube headers but with square tubing and square collectors.
John
Posted:
Wed May 27, 2009 12:26 am
by jfholm
here is the picture of the square tube headers
John