lt1 and lt4

[96z28]

Ok i wanted to replace my lt1 with an ls1 but from looking in to it its pricey. So i have decided to upgrade the lt1 to an lt4. My question is what is the difference between an tl4 and an lt1. What do i need to upgrade it, and how much will it set me back.(im broke i just did by my 1st car u know)

[N20LT4Bird]

Depends on whether or not you want a real LT4 or just the conversion kit. The real deal has a 4 bolt main block. Most guys just swap the heads, cam, intake, and rocker arms. For the conversion it will run about 2k for those basics. You may also want to look at headers, exhaust, PCM reprogramming, a larger throttle body, to get the full advertised 425 HP (total) supposedly gained from the conversion.

[Injuneer]

LT1 vs. LT4 Comparison

The "real" LT4 had a much milder cam than the "LT4 Conversion" kit that is mentioned above. With the stronger "LT4 HOT cam" that is included in the GM conversion kit, your HP levels closer to the ones mentioned above.

[N20LT4Bird]

LT1 vs. LT4 Comparison

Yup. that pretty much says it all.

[96z28]

2k is more then i really want to spend. Im sure the heads are what ran the price up head cost outragious amounts. How much would i gain from the hot cam, intake, and some headers. I would have to get the heads later.

[Squat13]

You dont need the intake if your not using the heads. The LT4 Heads have a .100 higher intake port for better flow, so does the LT4 Intake, so if you throw the intake on stock heads they just will not jine. The Cam(150$), rockers(285$), and springs (45$)are nice with out the head (Maybe 45 hp at peak) but the mod will really come to live with some heads with slightley bigger valves than stock. The headers may boost power 20 or so hp but they would be almost mandatiory on the LT4 Heads. also dont even waste your time with shorty headers, Go Long Tube. Also look in to LT1 Edit ir OBDII Tune depending on computer as both of these software programmes have downloadable peramaters for a lt4 CAM install.

[Injuneer]

You dont need the intake if your not using the heads. The LT4 Heads have a .100 higher intake port for better flow, so does the LT4 Intake, so if you throw the intake on stock heads they just will not jine. The Cam(150$), rockers(285$), and springs (45$)are nice with out the head (Maybe 45 hp at peak) but the mod will really come to live with some heads with slightley bigger valves than stock. The headers may boost power 20 or so hp but they would be almost mandatiory on the LT4 Heads. also dont even waste your time with shorty headers, Go Long Tube. Also look in to LT1 Edit ir OBDII Tune depending on computer as both of these software programmes have downloadable peramaters for a lt4 CAM install.

The LT4 intake will not even fit on LT1 heads.... there is an interference at the point at the valve cover rail on the heads that needs to be machined away. Although the LT4 heads have 0.100" taller parts, the LT4 intake does not. The intake manifold runners are almost identical in size and shape to the LT1 intake runners. The main difference is that the LT4 intake has more metal on the top, allowing the ports to be opened up more to match the flow capabilities of the LT4 heads.... but from the factory, the LT4 intake isn't all that good - at least not for LT4 heads. Appears GM ran out of money during the LT4 development program.

Don't write off "shorty" headers. The better, 1-3/4" mid-lengths will make as mush HP as the LT's in the correct application. I've seen the AS&M's that I run produce nearly 50HP more than the Hooker LT's at the 850HP level in a blown 383. LT's are great street headers, but can be a problem in locations with rigid emissions enforcement, or on a lowered car where ground clearance is limited.