LS in C4 for Auto X
09-09-2010, 07:52 AM
#1
Drifting
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LS in C4 for Auto X
Thinking about a LS swap in my 96 LT4 this will put me in group 3 for NCCC Auto X. Any body who has done this for Auto X see a big diff.? Or should I just stroke the LT4? Some input would be nice before I take the jump. Thanks
09-09-2010, 08:25 AM
#2
Le Mans Master
From what I understand the LT4s are underrated from the factory (another way to say they're *real* efficient on a chassis dyno). I don't think you'll see a lot of difference on an autocross track. Maybe during a DE, but that's not competitive.
It'll be a fairly involved conversion, but reasonable. Advantages are lighter weight, both your car and engine are OBD-II, lots of aftermarket support for LSx engines, etc.
Disadvantage is mounting points are different (including maybe the tranny), unknown front suspension interference issues, driveshaft may need to be shortened/lengthened, etc.
But it will surely be cool!
Have a good one,
Mike
It'll be a fairly involved conversion, but reasonable. Advantages are lighter weight, both your car and engine are OBD-II, lots of aftermarket support for LSx engines, etc.
Disadvantage is mounting points are different (including maybe the tranny), unknown front suspension interference issues, driveshaft may need to be shortened/lengthened, etc.
But it will surely be cool!
Have a good one,
Mike
Last edited by VetteDrmr; 09-09-2010 at 09:32 AM. Reason: fix typo
09-09-2010, 09:06 AM
#3
Le Mans Master
I think it would be worth it just for the lighter weight. It's one hell of a swap though. Don't think you'll just be dropping that in. I've also only heard of one doing a LSx swap with a ZF, all the others are using 4L60Es. There are some clearance and connection issues with the ZF and LSx motors. Good Luck.
09-09-2010, 09:32 AM
#4
Melting Slicks
Here's the details on my stroked LT-4 I did in 2007.
It was a blast to build and even better to drive.
Carbed & Stroked LT-4
(478.5 crank HP @5900 rpm) Aug 07 on eng dyno after rebuild
(413.7 RWHP @5900 rpm) Dec 07 on chassie dyno after 30 laps at CMP
LT block with Eagle 383 rotating assembly
Fidanza aluminum flywheel
Titan GM Sportsman oil pump
LT-4 heads, ported and decked
1:6 roller rockers
Cam specs
...Duration@ .050: Int.-242 Ex.-248.
...Lift: Int.-.586 Ex.-.581.
...Max head flow: Int.-278 cfm Ex.-187 cfm
GM LT-4 4 barrel intake #24502592
Quick Fuel- Wedge Float road race carburator #Q-750-CT
AED billet aluminum throttle bracket #6600R
Lokar throttle cable #TC1000HT36
Mallory fuel pressure regulator w/return #4309
Dual feed braided fuel line with 0-15 psi gauge
K&N X-Stream air filter assembly
GM water pump #EWP18-1119
MSD ignition box. Digital 6 plus #6520
MSD crank trigger
MSD Blaster 3 coil
MSD distributor #8489
Stainless long tube offroad headers with sensor bungs
AC delete bracket and pulley
Here's a few pics from Aug 07 during the dyno break in.
Installed in the car
It was a blast to build and even better to drive.
Carbed & Stroked LT-4
(478.5 crank HP @5900 rpm) Aug 07 on eng dyno after rebuild
(413.7 RWHP @5900 rpm) Dec 07 on chassie dyno after 30 laps at CMP
LT block with Eagle 383 rotating assembly
Fidanza aluminum flywheel
Titan GM Sportsman oil pump
LT-4 heads, ported and decked
1:6 roller rockers
Cam specs
...Duration@ .050: Int.-242 Ex.-248.
...Lift: Int.-.586 Ex.-.581.
...Max head flow: Int.-278 cfm Ex.-187 cfm
GM LT-4 4 barrel intake #24502592
Quick Fuel- Wedge Float road race carburator #Q-750-CT
AED billet aluminum throttle bracket #6600R
Lokar throttle cable #TC1000HT36
Mallory fuel pressure regulator w/return #4309
Dual feed braided fuel line with 0-15 psi gauge
K&N X-Stream air filter assembly
GM water pump #EWP18-1119
MSD ignition box. Digital 6 plus #6520
MSD crank trigger
MSD Blaster 3 coil
MSD distributor #8489
Stainless long tube offroad headers with sensor bungs
AC delete bracket and pulley
Here's a few pics from Aug 07 during the dyno break in.
Installed in the car
09-09-2010, 11:16 AM
#6
Melting Slicks
Sorry, I wasn't suggesting you go carb, I just wanted to show you a sample of the kind of HP a stroked LT could produce.
I purchased the car already stroked, but it had a F.A.S.T. system piggybacked onto the the factory ignition system. Never could get it to tune worth a crap, so when the oil pump fell off at an autocross and trashed the crank, I decided to yank it all out and go simple stupid with air-spark-fuel. I loved it, but carbs aren't for everyone.
I was also having head gasket issues along with the tuning issues, and that turned out to be someone had removed the steam cross over line at the rear of the heads. Ended up we had to toss the block also because of crappy repairs from crappy stroker clearencing in the block.
I purchased the car already stroked, but it had a F.A.S.T. system piggybacked onto the the factory ignition system. Never could get it to tune worth a crap, so when the oil pump fell off at an autocross and trashed the crank, I decided to yank it all out and go simple stupid with air-spark-fuel. I loved it, but carbs aren't for everyone.
I was also having head gasket issues along with the tuning issues, and that turned out to be someone had removed the steam cross over line at the rear of the heads. Ended up we had to toss the block also because of crappy repairs from crappy stroker clearencing in the block.
09-10-2010, 12:19 AM
#7
Burning Brakes
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Just FYI, but the LS motor in a C4 will put you into RP. Updateing and backdating motors is still not allowed in 3E, 3H, ect. In RP you must have a roll bar though.
Alot of the fastest cars at my region's autocrosses are group 1 or 2 LT4s. The rest of the fastest cars are C5 Z06s.
If you are lookign to just have more power, put a bigger cam and some better flowing heads on the LT4 and run that. At most autocrosses suspension work and tires will be more of an improvement than horsepower.
If you are just looking for something different to run, go ahead and put the LS into the C4 and have some fun. One of these days, my dad and I plan on building a 63 Grand Sport roadster replica with a 405hp LS6 in it. It will be an RP, fully gutted. We are shooting for around 2800lbs for total weight.
As for how easy it is to drop a LS motor in a C4 I don't know. What I do know is they make motor mount conversions that bolt up to a LS motor and then a standard 350 motor mount can bolt to that. They come in standard and 1" rear offset styles to accomodate different frames.
Alot of the fastest cars at my region's autocrosses are group 1 or 2 LT4s. The rest of the fastest cars are C5 Z06s.
If you are lookign to just have more power, put a bigger cam and some better flowing heads on the LT4 and run that. At most autocrosses suspension work and tires will be more of an improvement than horsepower.
If you are just looking for something different to run, go ahead and put the LS into the C4 and have some fun. One of these days, my dad and I plan on building a 63 Grand Sport roadster replica with a 405hp LS6 in it. It will be an RP, fully gutted. We are shooting for around 2800lbs for total weight.
As for how easy it is to drop a LS motor in a C4 I don't know. What I do know is they make motor mount conversions that bolt up to a LS motor and then a standard 350 motor mount can bolt to that. They come in standard and 1" rear offset styles to accomodate different frames.
09-10-2010, 07:21 AM
#8
Le Mans Master
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Just FYI, but the LS motor in a C4 will put you into RP. Updateing and backdating motors is still not allowed in 3E, 3H, ect. In RP you must have a roll bar though.
Alot of the fastest cars at my region's autocrosses are group 1 or 2 LT4s. The rest of the fastest cars are C5 Z06s.
If you are lookign to just have more power, put a bigger cam and some better flowing heads on the LT4 and run that. At most autocrosses suspension work and tires will be more of an improvement than horsepower.
If you are just looking for something different to run, go ahead and put the LS into the C4 and have some fun. One of these days, my dad and I plan on building a 63 Grand Sport roadster replica with a 405hp LS6 in it. It will be an RP, fully gutted. We are shooting for around 2800lbs for total weight.
As for how easy it is to drop a LS motor in a C4 I don't know. What I do know is they make motor mount conversions that bolt up to a LS motor and then a standard 350 motor mount can bolt to that. They come in standard and 1" rear offset styles to accomodate different frames.
Alot of the fastest cars at my region's autocrosses are group 1 or 2 LT4s. The rest of the fastest cars are C5 Z06s.
If you are lookign to just have more power, put a bigger cam and some better flowing heads on the LT4 and run that. At most autocrosses suspension work and tires will be more of an improvement than horsepower.
If you are just looking for something different to run, go ahead and put the LS into the C4 and have some fun. One of these days, my dad and I plan on building a 63 Grand Sport roadster replica with a 405hp LS6 in it. It will be an RP, fully gutted. We are shooting for around 2800lbs for total weight.
As for how easy it is to drop a LS motor in a C4 I don't know. What I do know is they make motor mount conversions that bolt up to a LS motor and then a standard 350 motor mount can bolt to that. They come in standard and 1" rear offset styles to accomodate different frames.
Yes changing style engines will put you in RP. You would have to stay GEN II small block in order to be Group 3.
Vettehardt, if that replica has a tube chassis and late model suspension (like a lot of replicas) it will actually be RPAF, RP Altered Frame.
09-10-2010, 09:47 AM
#9
Drifting
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You are correct, I looked it up in the Rule Book which I should of done in the first place. I do have the start of a roll cage that was going to be a winter project to finish it off.
Ummmm! More thinking now. Thanks
Ummmm! More thinking now. Thanks
09-10-2010, 08:53 PM
#10
Burning Brakes
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No it is going to be a stock frame with allowable streangthening for RP. We already have a 82 frame with a 67 tub, an aftermarket high rise hood, and a one piece front end for a 65. We also already have a 82 aluminum rear end to go in after we change gears, probably 3.70. Once we aquire the big hunk of aluminum for the front of the car (LS6) and tranny (M21?) we will actually start building up the frame.
Last edited by vettehardt; 09-10-2010 at 08:55 PM.
09-11-2010, 01:24 AM
#11
Le Mans Master
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No it is going to be a stock frame with allowable streangthening for RP. We already have a 82 frame with a 67 tub, an aftermarket high rise hood, and a one piece front end for a 65. We also already have a 82 aluminum rear end to go in after we change gears, probably 3.70. Once we aquire the big hunk of aluminum for the front of the car (LS6) and tranny (M21?) we will actually start building up the frame.
