Yeah exactly ,Steve is a good guy!Gregs672000 wrote:I agree completely that the "huge" hp gains that some manufacturers make frequently do not show up on the dyno....My friend Steve has noted very often that people come to him and want him to do such n such to a head for example to improve flow. But despite his efforts to educate and help his customer, they often do not want to think systemically, so they end up disappointed when it all comes together and they don't gain what they expect... well, they may have improved flow at the head, but they didn't take into account that the intake manifold has now become the restricting factor in the system and it needs work, and so on and so on. Kinda like healthcare and running the government... gee, who knew it was this complicated?
One of the points I was trying (not very well) to get across was that the U-solex is a special case. Unlike most Leyland crap, other beater engines, the R16, and certainly L-series, the Datsun Comp/Nissan set up for the U20 is really a well designed induction system- most pale in comparison.
All the things Greg listed are very good to improve on, but the intake manifold, solexes and 67.5 AC are so good, you aren't going to run out of Intake and air capability until well over 200hp. That's why I said the intake and filter box are not very good places to focus your attention in general.
The Bob Studdard d-prod car from 1987-89 dyno'd just over 225 on AV gas with the comp intake and carefully jetted 44's. I was there for the fun!
It my experiance, measurable gains will be minimal by tinkering with the intake and (open style) air filter.
These things will all make much more significant increases:
Make sure the distributor is excellent, advancing and timed right
Make sure the carbs are right and tuned, fix or replace
Make sure all cylinders have good compression or fix
Pick the right cam & cam timing.
Bore it .060 over or more.
Open up the exhaust.
Raise the compression like Greg (and prepare to deal with the new issues from that)
Lighten and stroke it.
Greg, when you have it pulling really well and think you have reached the limit, I would try other camshafts for fun. The cam is absolutely the heart of the engine, and changes to it and the cam timing affect the power and torque curves SIGNIFICANTLY. Totally change the characteristics of the engine for better or for worse. As with most things, going overboard on the cam will lead you down the wrong path of the maze.
If you have done all this stuff and it still isn't pulling hard, go back to the list-- it isn't the comp intake or the 67.5 AC --they have worked far too well on too many engines.
J
cards in the spokes sound would be good.....