To be meaningful, a chassis dyno pull should be "SAE corrected" for temperature, pressure, altitude, humidity, etc... so weather, altitude, etc. become meaningless in this discussion.

As far as the claims made by Summit and Pace, I believe that they are relying on the dyno tests done by More Performance and documented in at least two popular magazines, showing an engine dyno number of 429flywheelHP. What More was criticized for is that they did not mention all the items that were added besides the LT4 kit, including LT headers, larger TB, and a $4,000 MoTeC engine management computer for tuning, and apparently a few other unmentioned things.

 

the power claims are very possible with the correct supporting parts. and my formula put 270 to the wheels SAE corrected a couple weekends ago. it had a K&N filter and a 160 tstat which i didnt know was in there. previous owner failed to mention it. so id only be getting 110hp more than stock. one day ill do the LT4 conversion simply because it is better and allows for further changes. Trey

 

Why do so many people dog this kit? I fell to see how this is such a bad deal.

 

LT4 conversion kit includes:
LT4 heads, LT4 Hot cam, roller rockers, seals and gaskets. Price is about $2100 from what I hear.

I paid:
Ported LT1 heads: $1150
Cam: $260
Rockers: $270
Gaskets and seals: $100
Price is about $1780.

$300 to $400 less for:

Better heads: My ported LT heads flowed 278/191 @ 0.600 lift, vs. about 240/165(??) @0.600 lift for the LT4 heads. In addition, I got better valve springs, Ferrea valves, etc. on the LT1 heads.

My choice of camshaft. I got a bigger camshaft to take advantage of the added flow from the ported heads.

Better roller rockers. I got the Comp Pro Magnum rockers. They are lighter and stronger than the aluminum ones included in the conversion kit.

Better gaskets and my choice of head gaskets. I got the Felpro header gaskets, as well as the thinner Impala head gaskets to bump the compression ratio.

THAT'S why people dog on the LT4 conversion kit. You can get more performance for less money if you do the legwork of putting it together. Now if you want a simple no-nonsense package that will perform out of the box, then go with the LT4 conversion.

BRAD

 

Ported LT1 heads vs. Ported LT4 heads
The LT4 heads win hands down, I know the LT4 heads in this kit aren't ported but im looking a the potential that they have. So thats why im getting it! (im also going to be porting them) I already have a cam and rr's so ill sell the hot cam kit that comes with it so ill also have a cam of my preference. But I do this becuase I have the money. Not all people do so this wont be the best thing for some people who just want to get HP the cheapest way they can.

 

I did an lt4 conversion and I have 329rwhp with stock tb.and one cat.
still I have to do some programming to my pcm.
i seen lt4 conversion on the board doing 365rwhp with the right tunning but never close to 425hp
and in the next 2 month I will have my lt4 heads ported by a machine shop and get it dyno to see how much i will gain by just porting it

 

365hp is at or about 425fwhp. They weren't advertiseing 425rwhp.

 

Just to clarify:

An M6 @ 365rwhp = 429.4fwhp (15% drive-train loss)
An A4 @ 365rwhp = 445.1fwhp (18% drive-train loss)



I'm guessing that was an M6, so 365rwhp is not a bad number!