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I really did little to change the shape of the actual combustion chamber.
I mainly removed ceiling imperfections and sharp ridges right around the plug area. Anything that could create hot spots or irregular airflow.
There was a slight compression "ridge" that I removed and made symmetrical with the area around the adjacent valve.
The heart shaped hemi spherical chambers are quite efficient.
I did the least work "comparatively" in the chamber. Mainly all the detail work in porting. I did little shaping outside of smoothing and unshrouding the valves to the optimum measurement.
I figured my final compression by CCing the chambers and doing the math.
I could see going a little lower compression with some more judicious work in the chamber area.
IIRC Jesse has ported the chambers like I am talking about. Tapering back the sides for a forced induction build.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Joined: Sep 2000
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Originally posted by Derk2000:
1) That groove/cup thing that you cut out for the fuel injectors...how do you know the fuel is really going to shoot down the port?
The injector's spray gets evenly distributed to each... Riiiiight... 
I would estimate 35% of the fuel gets to secondary valve. It's main benefit is keep it clean. An added benefit is better fuel atomization.
The secondary port air enters at a faster speed and helps pull the injector spray.
Also the shared tumble port design helps as well.
Low speed atomization is much better. I had no problems tuning the 3L at idle or low load. Even cold.
The 2.5L without the secondaries ran very rich at idle. Deadly so when cold. Poor fuel atomization at low cfm demand.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Joined: Mar 2001
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Good Headjob!  Seriously though, it looks awesome. Got pics of your LIM?
2003 Sonic Blue SVT Cobra Coupe
2003 RedFire SVT Cobra Convertable
2005 Dark Toreador Red F150 XLT 4x4
2000 Black SVT Contour - Beater
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so with ~35% of the fuel going towards the secondary valve, do you think that's enough during high RPMs? That's not going to create strange combustion patterns within the chamber?
Derek
Scion xB 5-spd
Previous: 2000 Silver Frost SVT
Please share the road with cyclists.
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Originally posted by Derk2000:
1. so with ~35% of the fuel going towards the secondary valve, do you think that's enough during high RPMs?
2. That's not going to create strange combustion patterns within the chamber?
1. 100% of the fuel is still going to the chamber. It is just getting better mixed with the air charge.
2. As opposed to 100% going to only one valve?
One valve of lower velocity air.
Better fuel atomization makes for a more efficient engine.
I definitely have much better fuel atomization.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Joined: Aug 2000
Posts: 4,713
Hard-core CEG'er
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re: 1) Got it.  re: 2) Your answer to #1 answers #2 for me.  Thanks for the Q&A session... 
Derek
Scion xB 5-spd
Previous: 2000 Silver Frost SVT
Please share the road with cyclists.
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Joined: May 2000
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You are using a maxed out SVT UIM according to your site (unless it's in need of being updated). So, my two questions are this: Have you siamesed the UIM dual port design to make it match up to the heads better? What about the LIM?
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Originally posted by fastcougar:
You are using a maxed out SVT UIM according to your site (unless it's in need of being updated). So, my two questions are this: Have you siamesed the UIM dual port design to make it match up to the heads better? What about the LIM?
I left the UIM alone as you should.
The only work done to it was port matching the outlets to the LIM. I did that several years ago when I had the EHing done.
Yes the LIM outlets help transition flow into the tumble port inlets. I brought the primary inner wall over to the secondary inner wall. That should also help fuel mixing and getting a little more to the secondary valve. Also it eliminates the small dead space (reverse swirl eddies) between the 2 ports.
Everything was done for a reason or with a net result in mind. Like I always say the demon is in the detail work.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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