Cheap HP mods
Thread Starter
Melting Slicks
Joined: Jan 2003
Posts: 2,547
Likes: 77
From: Toronto ohio
Cheap HP mods
I have an 85 Corvette and have done some modifications. Just looking for cheap and easy mods. (Cheap as in best $ spent for most hp gain)
What has been done
Performance cat back exhaust
Performance chip
Air foil
Air Flow power coupler
Short shifter kit
air pump delete and underdrive pulleys
roller rockers ( valve cover leaking so I replaced rockers at same time)
your thoughts on these possible additions
headers? work involved?
SLP cold air induction ( Ohio car requires front license plate)
Other suggestions?
typical use
Just a nice summer day driver but does backup my everyday truck. So I need to keep it in running condition - no mod taking more than a weekend to do.
What has been done
Performance cat back exhaust
Performance chip
Air foil
Air Flow power coupler
Short shifter kit
air pump delete and underdrive pulleys
roller rockers ( valve cover leaking so I replaced rockers at same time)
your thoughts on these possible additions
headers? work involved?
SLP cold air induction ( Ohio car requires front license plate)
Other suggestions?
typical use
Just a nice summer day driver but does backup my everyday truck. So I need to keep it in running condition - no mod taking more than a weekend to do.
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
The addition of headers will bring the most noticable gain. You state you installed a cat back, so I'm assuming you kept the original cat. I found the simplest way to install headers was to use headers made by TPiS and the front Y pipe they offer. They install easily and the Y bolts right up to the original cat.
I found use of an adjustable fuel pressure regulator and Bosche III injectors to help as well. The 85 has a unique fuel injector setup. They used 24# injectors rather than 22# like the later years. The 85 runs at a lower fuel pressure than later years. The result is less than optimum fuel atomization. With an adjustable regulator set at 46psi and Bosche injectors, you will feel a difference. TPiS did dynos on a stock 85 engine and documented the Hp increase.
Forget the cold air intake. The air intake for the 85 is cold air. You can increase air flow by cutting the air filter lid and install a K&N filter.
I found use of an adjustable fuel pressure regulator and Bosche III injectors to help as well. The 85 has a unique fuel injector setup. They used 24# injectors rather than 22# like the later years. The 85 runs at a lower fuel pressure than later years. The result is less than optimum fuel atomization. With an adjustable regulator set at 46psi and Bosche injectors, you will feel a difference. TPiS did dynos on a stock 85 engine and documented the Hp increase.
Forget the cold air intake. The air intake for the 85 is cold air. You can increase air flow by cutting the air filter lid and install a K&N filter.
Burning Brakes
Joined: Feb 2000
Posts: 1,247
Likes: 2
From: Parker, Colorado, USofA
Your best bet isn't 'making hp', it's 'getting the HP back it had when new'!
Check your base ignition timing. I've yet to find a C4 of any age where it's still set to 6 degrees BTDC.
Check your TPS, .52 volts closed, 4.2v+ WFO...don't bother with any 'superdeduper TPS hop-up kits.
Are your plugs, wires, cap and rotor healthy?
Pull the screens off your MAF. (Some cars don't respond well to this...MAF equipped C4's do.)
ETA: Changed your fuel filter lately?
Check your base ignition timing. I've yet to find a C4 of any age where it's still set to 6 degrees BTDC.
Check your TPS, .52 volts closed, 4.2v+ WFO...don't bother with any 'superdeduper TPS hop-up kits.
Are your plugs, wires, cap and rotor healthy?
Pull the screens off your MAF. (Some cars don't respond well to this...MAF equipped C4's do.)
ETA: Changed your fuel filter lately?
Last edited by RocketSled; Jan 20, 2010 at 09:57 PM.
