I'm starting my Teksid 2v project, and i've been trying to get a complete list of the factory specs for the 2v engine in my 2004 GT. I'm tentatively planning to re-use the 2v heads, maybe a bit of porting/polishing if it makes sense, and some mild cams, if i can find a grind that gives me a bit more low to midrange power without sacrificing too much fuel economy. No big deal, i just want everything is all : )
Here's what my research has uncovered. Interestingly, some fairly well-recognised sources have listed conflicting numbers, so if somebody sees something here that they know is bogus, i'd love to hear the correct numbers!
4.6 aluminum Teksid block weight: 86lbs
4.6 iron Romeo block weight: 154lbs
Both Teksid and Romeo blocks Bore: 3.552"
Both Teksid and Romeo blocks Stroke: 3.543"
Bore Spacing: 3.937"
Deck Height: 8.937"
Connecting Rods, (Powdered Metal in GT, Forged in Cobra): 5.933"
Rod Journal diameter: 2.086"
Main Journal diameter: 2.657"
Crankshaft: 6-bolt Cast Iron in GT, 8-bolt Forged Steel in Cobra
Pistons: Hypereutectic with .145" (18.5cc) dish in Gt, flat top (some forged, some hypereutectic) in Cobra
Heads: 2v, 42.5cc combustion chamber
4v, 54cc combustion chamber
Combustion Ratio: 2v 9.74 to 1
4v 9.85 to 1
2v intake valves: 1.752", 7mm stem, length 4.682"
2v exhaust valves: 1.418"
Roller Rockers: 1.81 to 1 ratio
Cams 2v: intake lift .505", duration 200°
exhaust lift .531", duration 208°
Lobe Separation: 113.5
I'm figuring out what compression ratio to use. This will be a NA engine, daily driver (spring/summer/fall), mainly highway driven. If i can find a set of TFS heads for a reasonable $Cdn price, i'll buy them. Otherwise, i'll rebuild the factory 2v heads.
Anybody see any glaring flaws in these stats? Can anybody give me an idea of the effect compression has on power/driveability/fuel economy? If the stock 2v compression is indeed 9.74 to 1, what change can i expect to see if i bump it to 10.5 to 1? I found an article that said a 10% increase in compression results in a 1-3% increase in power, is this right?
The Teksid is being align-honed this week. I have a forged crank (Kellogg?). I'm going to use Scat forged rods. I need to figure out what dish the pistons need to keep compression under 10.5 to 1, so as to be able to use 91 pump gas.
What do you think? ...regards, kevin
ps. any TFS TW185 heads gathering dust in somebody's shop?
Here's what my research has uncovered. Interestingly, some fairly well-recognised sources have listed conflicting numbers, so if somebody sees something here that they know is bogus, i'd love to hear the correct numbers!
4.6 aluminum Teksid block weight: 86lbs
4.6 iron Romeo block weight: 154lbs
Both Teksid and Romeo blocks Bore: 3.552"
Both Teksid and Romeo blocks Stroke: 3.543"
Bore Spacing: 3.937"
Deck Height: 8.937"
Connecting Rods, (Powdered Metal in GT, Forged in Cobra): 5.933"
Rod Journal diameter: 2.086"
Main Journal diameter: 2.657"
Crankshaft: 6-bolt Cast Iron in GT, 8-bolt Forged Steel in Cobra
Pistons: Hypereutectic with .145" (18.5cc) dish in Gt, flat top (some forged, some hypereutectic) in Cobra
Heads: 2v, 42.5cc combustion chamber
4v, 54cc combustion chamber
Combustion Ratio: 2v 9.74 to 1
4v 9.85 to 1
2v intake valves: 1.752", 7mm stem, length 4.682"
2v exhaust valves: 1.418"
Roller Rockers: 1.81 to 1 ratio
Cams 2v: intake lift .505", duration 200°
exhaust lift .531", duration 208°
Lobe Separation: 113.5
I'm figuring out what compression ratio to use. This will be a NA engine, daily driver (spring/summer/fall), mainly highway driven. If i can find a set of TFS heads for a reasonable $Cdn price, i'll buy them. Otherwise, i'll rebuild the factory 2v heads.
Anybody see any glaring flaws in these stats? Can anybody give me an idea of the effect compression has on power/driveability/fuel economy? If the stock 2v compression is indeed 9.74 to 1, what change can i expect to see if i bump it to 10.5 to 1? I found an article that said a 10% increase in compression results in a 1-3% increase in power, is this right?
The Teksid is being align-honed this week. I have a forged crank (Kellogg?). I'm going to use Scat forged rods. I need to figure out what dish the pistons need to keep compression under 10.5 to 1, so as to be able to use 91 pump gas.
What do you think? ...regards, kevin
ps. any TFS TW185 heads gathering dust in somebody's shop?
