Just a random thought / question about putting an LT5 into a custom application.

[Corvette95]

After seeing some pics on various sites about custom LT5 engine swaps into non / different corvette cars, without the vacuum pump, how do these people get the secondaries to work, I figure the ecu will be programmed not to need the power key, but they dont appear to have the vacuum pump on these applications.

[Tom]

The secondaries will work off of the normal engine vacuum. The external vacuum pump is only required if you are going to stay at wide open throttle for a long period of time where there is very litle engine vacuum. The Corvette shop manual explains how this system works under different conditions.

[rkreigh]

on a VERY long sustained WOT run you can lose enough vacuum theoretically for the secondaries to not work. in practice, I don't know if anyone has had this problem as many have reported the secondaries work fine, but GM put it there for a reason.

my take on it, remove the secondaries and reprogram the chip. it works really well, reduces the complication under the plenum, doesn't really hurt the low end torq that much, and makes the car more enjoyable as parts left out don't break. many folks can setup the chip now, it's not that hard and the parts are valuable to sell off.

what application do you have in mind??

[Kevin]

if i could find a ported stock cube car to drive without secondaries in it, i may have marc do it to mine when i send it to him

[Corvette95]

Originally Posted by rkreigh

what application do you have in mind??

None yet ....Two LT5's sitting in the garage on stands and nothing to do with them makes for a lot of interesting thoughts.