Does anyone have any experience with the GM performance LT1 to LT4 conversion package? In summite racing catalog it says it's worth 425??! Is that what the maximum i is capable of? All info will be a help. I am looking for a HP figure with this upgrade. THANKS!!

 

from everything i've seen it is quite the exageration.

i think with a very hot tune, you could maybe get it up to 400 at the crank...like 340-350 at the wheels.

there are much better heads/cam setups for much better power.

a good set of ported LT1 heads and a above average cam will make 400 to the wheels i think

 

425 HP in an automatic with an 18% loss coefficient is 348 to the wheels.
In a manual with a 14% loss, it is about 365. I think it's very doable, but you'd have to have long tube headers and a good tune.

 

yea, i heard they used a very very capable tuning machine to get those numbers at the crank, not the wheels
i would also suggest getting a good heads/cam package and blow that lt4 conversion away

 

Ion, i guess those numbers do look reasonable...it just seems that nobody is ever happy with the results from their kits.

seems like i see 330-40 all the time...