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rob82

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Everything posted by rob82

  1. Got to ask why? I see in your signiture that its a track car but I would seriously think about just using a good quality internal pump with maybe a larger sump volume. Most external setups only introduce less redundancy for no real gain in horsepower. There are plenty of track rb's running internal pumps with no issues.
  2. Your AFM wont be metering the air that is drawn in through the catch can vent - leaning the engine out.
  3. Has anybody looked at venting the head water jackets in order to reduce localized boiling above the exhaust side of the chamber? I've tuned a high comp ls1 with this method of cooling and we were able to get the timing back up to around 22degrees (from16-17) and we gained about 25rwkw. It must be a problem with the length of the rb blocks. The other gain is a lower coolant pressure which May reduce pumping losses.
  4. Never seen a STD ca18 with a good fuel system/afm be lean! Pump will fix your problem.
  5. Does the load go up on decel? If so you are getting maf reversion as in the air is reverting back through the afm causing the engine to over fuel. There is no way around this issue other than installing a bov that works properly which is about 10% of the manufacturers you described earlier! And don't think because it's branded that it means it's good! I went through this loop three times with a customer with a certain brand of intake which caused inconsistent fueling on his evoX! Also if worst comes to worse you need the aac doing as little as possible. Ie disconnect the aac set the timing low at say 5 degrees then screw the bypass air valve out to get close to your desired idle speed then reconnect the aac. I would aim for a 5degree idle with 20degrees as it goes to sag.
  6. There is no way to tune a PFC around maf reverse caused from running no bypass valve. All you will be doing is fudging one section of the map to stop overfilling of another section of the map. Ie you may help the idle sag but create a lean spot once on throttle. If you want your car to be in a proper state of tune put the bypass valve back on the car and get over it.
  7. Positive overlap only becomes an issue at high rpm when the exhaust back pressure increases. Plus I wouldn't call -5's on a 26 being overly restrictive! What do you think an rb25 cam phaser does - increases overlap lap by advancing the inlet cam between 1400 and 4700rpm (low to medium revs) Evo9 does the same but has varying angles Avcs equipped wrx's does the same but varying angle Dual avcs (09sti) advance inlet and retard exh to increase positive overlap Now some of the STD ihi turbos on the STD wrx's is what I would call a restrictive exhaust side. With free flowing exh we can generate 14psi at 2000rpm rev limited at 6700rpm!
  8. I love that comment because in a variable cam engine overlap is exactly what you want at low to medium revs! But I agree with small duration and lots of lift - as long as the valve train can handle the ramps/inertia
  9. Good stuff - happy to help.
  10. If your that far advanced and the power isnt dropping off at that rpm then those cams have dropped your dynamic comp that much it probly won't really react to much cam timing movement at all. I think it would be a wise choice to go to the smaller duration 252 @10mm lift. I would think that you would gain responses without loosing too much top end. To the original poster I would recommend the same cams if you must go with that bucket size change.
  11. Did you wire it with the designation on the plug or on the afm? It's been a while since I've done one but I'm pretty sure the plug designation is reversed From the afm designation.
  12. We managed an 11.2 at 130mph full weight with street radials running an rb30/25 gt35 manual in a vl on pump with around 350rwkw. Guy driving was very good though - now test drives jags for a living. I would say that would be close to the benchmark for 350rwkw manual.
  13. They do have larger ports and valves but I've never really noticed any difference in power out of the box and they seem to respond the same amount once cammed as well. Its all about port velocity just ask nathan higgan what he does with the heads. Aspirated performance isn't about bigger is better - unless your talking about cubes! PS - everybody's got a mate with LS that makes a sqillion hp. I just find it funny that cars I've tuned with similar mods to other cars but with 50rwkw less seem to keep up!
  14. Happy dyno's in my opinion - I've tuned countless ls1 ls2 l98 all the way up to ls7 with varying sizes of cams and I've never seen that kind of power on our dyno. I've made upward of 350rwkw but it's always been with cubes (427) and large cams 238@50 and beyond. STD ls2 auto with exh and tune will make around the 230-240rwkw mark with a cai and similar size cam 225@50 you will only see around the 280rwkw mark with low rpm torque loss!
  15. Ign on then back probe the signal wires with a multimeter as it's just a optical sensor with a hall output so you should see a high voltage on a gap. Turn it very slowly thou.
  16. Man I love those cam & tune packages that add 100rwkw they are just the bomb! It's just a pity they don't exist!
  17. When we've gone to crank trigger setups on gtr's with autronics we've found the engine can go back to being 1 degree sensitive! Without crank triggers I've seen up to +/- 6degrees timing variation on the really bad ones.
  18. That cam timing is not right for STD cams. Good for bottom end power but it will kill top end. Try inlet at 4ad, exh at 2ret.
  19. Seen this issue many times before wait until you add another 25mm of deck height and see how far the timing goes out about 6000rpm!! They really need an interface that converts the signal from 36-2 to a 360 degree signal - that way the PFC guys can play too!
  20. Totally possible - leak down test time.
  21. Yeah - the charge velocity reamins close to sonic velocity irrespective of boost level. Its really just the density of the charge that will change. The xr6T manifold on BA/BF's is really easy to convert back to dual length by adding the valves and actuators and drilling a few holes.
  22. I think you will find that the sonic velocities at the length most runners are will have very little effect if you working from atmospheric pressure to 2bar of boost pressure. You've got to remember that air travelling in and out of an engine is close to sonic speed so with a 0.5m long runner your talking about timing multiple resonance pulses (depending upon rpm) - which essentially dulls the helmholtz effect. I can tell you from experience in all the non OEM boosted applications I have seen on variable length manifolds I've never once had to move the rpm switch point - to my amazement! If I were you I would be looking at designing two different runners with differing cross section area and length and then switch between the two. Use a plenum which is suitable sized to deliver an even charge across all cylinders. BTW the best piece of varaible length intake manifolds mass produced is the FR500. I have tuned a stroked modular 4.6-5.4L V8 with one of these intakes - power difference from long runner to short runner was about 60rwkw!! Best sounding v8 I've ever tuned! BTW these intakes are magnesium and cost around $7000.
  23. Not on me - its the same intake manifold ford has used on EF-BF I6 aspirated engines.
  24. Sorry it was a Cosworth intake manifold - not just plenum. And to add I was also involved in tuning an XR6T with the aspirated duel inatke length manifold installed. From memory the boost was on about 400rpm ealier along with a huge increase in torque.
  25. Hmmm - what GTSboy has said is correct. There is some misinformation in this thread though. Intake manifold tuning is just as critical on a turbo charged engine as it is on an aspirated engine. I have delived into manifold design quite extensively but my design has never come into fruition. I have read multiple SAE documents and have personally seen many different intake manifold designs over the years as a tuner. I can tell you that even the top manufactures get it wrong. The best fail I witnessed was the cosworth plenum on a mazda SP23 MZR I4 2.3L. It lost power throughout the entire rpm range until 200rpm before the rev limit where it made a bee's dick more hp. The std plenum was dual runner length thermoplastic design where the cosworth was staic runner length with shorther runners and larger cross sectional area - it was never going to work. If you want to do something difference - create a dual runner length plenum or introduce a way of dynmaically modifing the cross sectional area of the runner. Or change the material. Think outside the box! PS - in this point in time with varaible cam control, direct injection, varaible turbine turbo's and HCCI I beleive the intake manifold is the only major part of an engines design that is yet to be exploited.
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