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Engine Mechanical TopicsDiscussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.
Where are you at? No shop. Just a garage. I sent the heads and jugs off to Don Dorfman, HD Street Performance. One of the best at getting heads to flow. Got mine flowing 320cfm @ 28" 7000rpm. 1.980/1.615 valves.
Cedar Rapids area , no head work done other than CCing for compression .
Cedar Rapids area , no head work done other than CCing for compression .
Hard to say what's cam and what's lack of flow but no porting definitely a big part if it. Struggling in the 3500rpm area too. What exhaust?
Keep in mind that's STD. Those numbers would be less in SAE. My STD numbers were 130hp/129torque. Typically the difference is even more.
You're really more like 110/117 in that neighborhood for SAE numbers. Not horrible for no real headwork tho.
Hard to say what's cam and what's lack of flow but no porting definitely a big part if it. Struggling in the 3500rpm area too. What exhaust?
Keep in mind that's STD. Those numbers would be less in SAE. My STD numbers were 130hp/129torque. Typically the difference is even more.
You're really more like 110/117 in that neighborhood for SAE numbers.
Fullsac DX head pipe with S&S Grand National slip -ons , S&S stealth air cleaner.
Fullsac head pipe with S&S Grand National slip -ons , S&S stealth air cleaner.
Should be decent enough there on the exhaust. Could always have Don work his magic on the heads this off season and bump those numbers significantly. Get that hp close to 120 SAE. Upper teens anyway. Torque in the mid 120s SAE.
I was a little disappointed in the torque , he did the same build on a 2015 103 and got 112 / 130 , when I first talked to him a couple years ago he was using the 590's. Those are some good numbers from a 107 build , your only an hour away from me , do you have a shop ?
The best thing gunner did was to have someone else do the critical work, especially the heads and tuning. If you want to make the close to the same numbers, you need to copy the build..
In the case of the 103, you need to copy the build. That don't mean only cams, heads, displacement. It also means throttle body, air cleaner, exhaust header, mufflers, compression ratio and probably a couple more things.
The best thing gunner did was to have someone else do the critical work, especially the heads and tuning. If you want to make the close to the same numbers, you need to copy the build..
In the case of the 103, you need to copy the build. That don't mean only cams, heads, displacement. It also means throttle body, air cleaner, exhaust header, mufflers, compression ratio and probably a couple more things.
I had a shop do all the work , it's what they call their level 1 / basic 107 big bore kit , I did add the 55mm throttle body with 5.3 injectors. Same shop same build on a 2013 103 but used a V&H pro-pipe vs my Fullsac and got rid of the dip in the torque curve + 4 ft lbs of torque , I wanna say I'm @ 10:6 to 1 compression.
I had a shop do all the work , it's what they call their level 1 / basic 107 big bore kit , I did add the 55mm throttle body with 5.3 injectors. Same shop same build on a 2013 103 but used a V&H pro-pipe vs my Fullsac and got rid of the dip in the torque curve + 4 ft lbs of torque , I wanna say I'm @ 10:6 to 1 compression.
I wouldn't say it's "struggling" in the mid range, pretty flat up to that point. Without the cam card it's just speculation, but I'd guess they're on the larger side as an attempt to crutch the stock heads.
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