| quote | Originally posted by dobey:
Why do people insist on doing multiple QUOTE blocks in a single reply? It makes the "Quote" button on the post not work.
Anyway, yes you are getting some gains from the big exhaust system, because there is still less restriction. But because your exhaust is too big, the exhaust gas is not moving out of the system fast enough. As it expands in the piping, the gas slows down, cools, and condenses, becoming heavier and harder for the engine to "push" it out of the system.
Your primaries should probably be about 1.25" and each primary should be about 35 inches long, and collect into a 2" system. What RPM is your valvetrain built to handle? |
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Oh and sorry on the multi quote.... I used to get slammed for posting with one quote per reply and have a ton of replies grouped together.
Not sure we ever came up with the RPM abilities of the set up... You are asking the questions that were all in the theory stages... I was learning the mechanical end as we went and my partner in crime was a v-8 guy. We were doing alot of paving back then in the f-body v-6 group. Too much NEW uncharted teritorry. 3.4 block was out of a 50,000 mile car and left as is.
This was the latest combo we were working on after I found I had a cracked head. Replaced the heads (iron 2.8/3.4 rwd heads) and ported & polished the new ones more extreme then the originals (need to bench flow them) & ported the lower intake more to match. The car was choking & needed more air!
Valve train is this...
Car has new lifters & rods
Comp Cams 1.6 Roller tip rocker arms
Comp Cams 986-16 Springs
Multi Angle Valve Job retained stock valves
Reed Cam: TM276/282H12A2 (223/228 w/ 471/480 lift on 112 int C/L is 108)
Never tested it all together sadly... botched paint job in the engine bay and getting a shop to fix it has been holding things back
With an air /fuel ratio of 11...Last dyno run (added Truleo and 65mm Ford TB) on the cracked ported head had the car putting down
Max Power = 143.3 @ rear wheels (+20% for automatic tranny losses) = 171.6hp @ the fly wheel
171.6hp compared to 160hp from the factory. HP hits 140 from 4700 and holds pretty level through 5700. 143 peak is 5000-5300
Max Torque = 258.1 @ rear wheels (+20% for automatic tranny losses) = 309.72ft-lbs @ the fly wheel
309.72 compared to 200 from the factory... TQ peak is 2500 with an extreme drop due to stall...
TQ and HP cross at 52-5300
So with no other changes then the intake and TB swap I gained 36.8Ft lbs or TQ at the wheels = 44.16Ft/lbs @ the flywheel.
Oh and as far as how quick the exhaust could exit the system... the cut out was located like so (this was a pic of the old 2.25 system, but in the same place none the less)
[This message has been edited by redraif (edited 10-11-2011).]