-get the cold air.
-4-2-1 headers. no names work fine.
-remove a/c (less pulley usage)

theres some more power squeezed out.

 

Different intake manifold. Z6 works and is cheap. Header helps, cam will help.

 

-get the cold air.
-4-2-1 headers. no names work fine.
-remove a/c (less pulley usage)

theres some more power squeezed out.

not to be confrontational, however everything I have read about engine theory and design has told me that a cold air intake is better for low rpm torque (usually below 4k).

A cold air intake has a longer tube, which has a Helmholtz resonance tuning affect on the air column inside the intake tube. The length of the pipe effectively 'tunes' the intake air charge to move through the intake the quickest at a certain speed (around 3400 on a honda) and actually hurts top end power. The result is a dyno chart with a higher torque curve lower in the rpm range, which actually drops off quicker as the rpm climbs higher out of the 'sweet spot.'

4-2-1 headers yes no name is fine and there are performance gains to be had.

Try disconnecting your power steering and AC belts from the car, and go for a drive. Does it feel more powerful? (it's misleading to 'feel' for a power increase because your body interprets a sharp increase in torque as much more powerful, even though the car got slower overall because you lost torque higher in the rpm range.)

sweed is 100% on point.

 

Try disconnecting your power steering

What power steering? :wink:

 

Heh heh ^^

let me be the first to suggest plugs, wires, cap and rotor if they are old.

also get the timing set with a timing light.

some people swear by seafoam but its never excited me.

 

best way is a cam and dual valve springs... then rev the piss out of it till you get valve float..
lol don't do that...
but a delta cam with some nice dual springs will let your engine breathe better and have more top end.
CAI or HAI (hot air intake), header, etc.. will barely give you anything. Unless you get a nice tune. I think having a tune-up is an obvious thing that shouldn't be mentioned, but its easily overlooked.
Start off small like those guys said, then if you start getting rpm happy, then its time for some nice bumps on your CR with p29's, delta, springs, and a tune... even then, no offense but d series n/a +slow

 

Just gonna leave this right here..

Engine Mods:

- D16A6 head and block, stock pistons, valves, springs, no overbore, new rings and 3-angle valve job
- 92-95 Civic Si head gasket, approx 9.5:1 compression
- 92-95 Civic Si Intake manifold and TB, manifold is DIY stepped just past the throttle body with a dremel
- Head is DIY ported 3/4" deep on the intake side with a dremel to match manifold
- Stock 91 injectors and FPR
- Ignition timing advanced to 22°, 93 octane fuel
- SOHC ZC Camshaft from Carb'd model
- 92-95 Civic Si dampened crank pulley with accessories shaved off
- Iceman short ram intake
- DC Sports 2-pc header, lightly DIY ported at inlets
- Magnflow/Carsound OEM cat
- Greddy SP2 60mm stainless midpipe and muffler
- Stock 91 Si ECU

 

Thanks for all the replies. I suppose I should have been more clear about how restrained it is above 6k and about what I'm willing to do about it. First off, past 6200 rpm my car is faster if I upshift to the next gear. By this I mean it is so restrained near redline that it will accelerate faster in the next gear than in the current one.

I bought this engine with ~156k on it and it now has ~ 260k. The engine has been felt this way at the top end for the entire time, through multiple spark plugs, fuel filters, dist cap/rotor, plug wires, etc. I recently did a near complete rebuild which included
cleaning and resurfacing the head
piston rings + hone cylinders
lap valves
valve stem seals
spring seats
y8 headgasket
arp head studs
and all relevant oil seals/gaskets

I don't really want to go into engine internals because doing it right requires a tune, something I do not have the time to learn how to do myself but am unwilling to pay for.

I am leaning towards the exhaust because I don't remember the lack of power being as severe when I didn't have a cat on the car. Hopefully a z6 (or y8) intake and aftermarket (or y8) exhaust manifold will help cure my ills.

Also, I agree with corksil about the CAI. Additionally, I will never put another CAI on a car because I hydrolocked my B18C by driving through a puddle once.

 

Yeah dude, live and learn about the hydrolock :shock:

It's sad but sometimes it takes a catastrophe to b!t<h-slap some sense into you. I know I've destroyed a few motors.... won't make those mistakes again... but hey! There are endless amounts of mistakes still LEFT to make :lol: (not funny) *crickets*

Just curious what your compression numbers are across each cylinder? Pull the ECU Backup fuse, and hold the throttle wide open - pull all the plugs out and stick the comp tester on each cylinder, let it crank seven times (that's how I do it). That will tell you a lot about the health of the motor and if you're beating a dead horse trying to get more power out of an unhealthy motor.

 

Will check compression this week. I just moved to Salt Lake and don't have a garage. So my tools are in storage for the time being I haven't checked the compression in a while, but I can't imagine it's that bad since I just did the rings and lapped the valves.

 

compression/power is probably going to seem low, cause of the altitude you're at. altitude sucks...