LT5 Assembly Project

[XfireZ51]

I don't know. 380 or 368 doesn't do it for me like 396 or 427.
And we now have 350's that are equaling the output of 368s of just a few years ago.

[Pete]

Originally Posted by Toni94ZR1

I was following this thread since the beguining (2008) and in 2009 I disassembled the engine and began, on spare time, doing port work and preparing all the engine parts.
Now I'm waiting how your engine runs with your regrinding cams to do it in my engine, and beguin the engine assamble.
I'm anxious to see a video of your engine running !!!!
You did a great job

My brother's ZR1 have a new battery I can send to you (Barcelona to USA) if this shorten the time to see a video of car running

Thanks for this great post...

Toni
(Barcelona)

Toni,what are you waiting for regrinds work all the fast Z's have regrinds,nuff said.
No need to wait,just do it.

Pete

[Pete]

Originally Posted by LGAFF

sound is really poor, sounds like a few rocks in a tin can....I called Dominic and let him listen in, sounds good....but needs a tune.

TB plate was sticking it idles at 750 with a big lope


Really wish I had a better camera

Yeap,that's Corsa for you wait till you hear it from the outside at WOT,talk about loud fart can.
and your down 10-15hp with that exhaust.

Pete

[Toni94ZR1]

Originally Posted by Pete

Toni,what are you waiting for regrinds work all the fast Z's have regrinds,nuff said.
No need to wait,just do it.

Pete

Yes Pete, I think is the way to go do a regrind and as xfirez51 said, the performance of a 350 + full porting + regrind are equivalent to a more expensive 368 + porting done few years ago.

Pete as I can see you are an expert guru on LT5 cams configuration, are this the best (power + drivability) regrind allowed on a 94Z's stock cams?
Duration @ .050
Intake: Primary 222 dur/415 lift , Secondary 236 dur/425 lift
Exhaust 222 dur/415 lift

Are the stock 94 LT5 cam specs the following?
Intake Prim 214/390 Sec 229/390
Exhaust Duration 214/390

Toni

[Pete]

Originally Posted by Toni94ZR1

Yes Pete, I think is the way to go do a regrind and as xfirez51 said, the performance of a 350 + full porting + regrind are equivalent to a more expensive 368 + porting done few years ago.

Pete as I can see you are an expert guru on LT5 cams configuration, are this the best (power + drivability) regrind allowed on a 94Z's stock cams?
Duration @ .050
Intake: Primary 222 dur/415 lift , Secondary 236 dur/425 lift
Exhaust 222 dur/415 lift

Are the stock 94 LT5 cam specs the following?
Intake Prim 214/390 Sec 229/390
Exhaust Duration 214/390

Toni

Yes,on the stock cam specs.

I don't see the reason for split intake cams,but the specs look good.
Here's what i have in my 350
Intake: .242 .450 pri/sec

Exhaust: .224 .420

Pete

[Toni94ZR1]

Originally Posted by Pete

Yes,on the stock cam specs.

I don't see the reason for split intake cams,but the specs look good.
Here's what i have in my 350
Intake: .242 .450 pri/sec

Exhaust: .224 .420

Pete

Wooow Pete, you have a very big intake cam, this will do a rough idle and high speed idling?

Your relative little exhaust cam I think is because you don't loose too much low end torque and car driveability, large exhaust duration will probably cause a decrease in power on a stock 350.

Yes, same (Prim, Sec) intake lobe profile shape is the best design and give more power, diferent profile cause a different (Prim, Sec) air speed flow filling the cylinders so can cause turbulent air flow in the inlet runner when Plenum and IH are Siamese .

As I will assemble stock cams regrinds or not, I only do siamesed runner on the plenum, the IH and Head are no siamesed only porting to 36'5 mm to keep independent air volume storage and air speed. Siamesed inlet plenum it's a must because total inlet length measures about 14 in. from plenum to valve seat, too long and the plenum inlet runner have a bad 90 degree curve, I smooth the short corner ( make the radius bigger ) as much as possible of the 90 deg. curve of the plenum port to minimize the air flow loose.

To get a higher lift the lobe base circle had to be regrind (decrease in base diameter) keeping the same lobe nose. The primary lobe has a big lobe acceleration rate and at the secondary the acceleration rate is less. If regrinds both base circles to get .425 lift (prim, Sec) the acceleration rate on primary will be too high so will need bigger valve spring to control floating valve problem. The solution to decrease the acceleration rate is increase duration @ .050 but the primary lobe does not allow do this, needs to be reground and then regrind. .415 lift may be are the maximum lift primary lobe admit to keep the floating problem under control. If regrind the base circle to get a .415 lift i think the maximum resulting duration will be about .222. on a primary lobe. Doing a cycle graph will tell me the max duration allowed when regrind to .415 lift.

As I can see your inlet cams are not the stock regrinds, may be are a SGC stage III ?

And your exhaust cams I doubt if are stock regrinds or SGC stage I ?

As the inlet and exhaust cams are different, not a single cam engine, you can modify the Lobe Centerline Angles (LCA) so the amount of overlap. The more overlap (tight LCA) an engine has, the greater tendency it has to run badly at low rpm, low vacuum and bad idling but good cylinder filling so more power.

Which are the timing numbers of your cams, LCA or Overlap and Intake Open Degree from TDC. ?

Pete I know my English is not very good, if you don’t understand what I said please let me know and I will explain on a different way.

Thanks very much
Toni

[Toni94ZR1]

Lee, Which are the timing numbers you set on your regrind cams, LCA or Overlap and Intake Open Degree from TDC. ?
Toni

[LGAFF]

114 intake, 108 Exhaust cam timing

Dominic did a chip for me so the car is more drivable....but it was a generic....need to tune it on a dyno and make some corrections. Car is running good oil pressure is great, running cool, no issues so far.

Big thanks to Pete, Bob, and Dominic for their advice during the build


Can't forget Jerry for getting gaskets to me and keeping track of ones I was missing....thanks Jerry!

[XfireZ51]

Lee,

[Polo-1]

Originally Posted by Toni94ZR1

Polo-1, 380ci is at the same price than a 368 ?
If i'm wright ,on a 368 engine only change liners and pistons from stock, but on a 380 ci need liners, pistons and a new crankshaft and maybe conecting rods.

You can make up to 411 ci out of the stock crank and stock rods. For most it will be 377 to 382 ci. The cost is $350 more then a 368. The added torque from the longer stroke and getting you closer to a big inch LT5 on the cheap.
After doing this package (380ci ) I would recommend a longer then stock rod ( 5.850 or 6.00 ). The stock rod is ok it will not break, just a little on the short side (5.74).