Just a random thought / question about putting an LT5 into a custom application. - ZR-1 Net Registry Forums

Corvette95 · 12-03-2006

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 · 12-04-2006

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 · 12-05-2006

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 · 12-05-2006

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 · 12-05-2006

Quote:

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.

12-03-2006	#1
Corvette95 Join Date: Jan 2006 Location: Decatur, AL Posts: 1,119	Just a random thought / question about putting an LT5 into a custom application. 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. __________________ Corvette95 Registry and Forum (*************) 1989 C4 Conv Wht/Gry Auto Hardtop Top Flight SOLD 1995 C4 Coupe Purple/Blk 6 Speed 1989 C4 Conv Wht/Red Auto SOLD 1996 C4 Conv Black/Tan Auto SOLD 1994 C4 Coupe Wht/Blk SOLD 1995 C4 ZR-1 White/Gry #278 Dual Dunn Head SOLD 1986 C4 Coupe Black/Red 4+3 SOLD 1990 C4 ZR-1 Red/Red #0454

12-04-2006	#2
Tom Join Date: Jan 2004 Location: Southern CA Posts: 108	Re: Just a random thought / question about putting an LT5 into a custom application. 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.

12-05-2006	#3
rkreigh Join Date: Jan 2004 Location: Alex VA Posts: 1,087	Re: Just a random thought / question about putting an LT5 into a custom application. 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?? __________________ 95 390 LPE ZR1 (505 rwhp) LSV = Lingenfelter Super Vette Twin Turbo 2003 Z06 (800 RWHP)

12-05-2006	#4
Kevin Join Date: Jun 2005 Location: pittsburgh Posts: 4,632	Re: Just a random thought / question about putting an LT5 into a custom application. 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 __________________ It's not the car, it's the people - Doug Johnson 90 r/r "KEYS ON" nick named "T.L.B"