LT5 Assembly Project

[Blue Flame Restorations]

Originally Posted by 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!

AWESOME!!!!!!!!!!

[Paul Workman]

Originally Posted by Toni94ZR1

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

Lee...like Brett said! CongratZ!!

Toni,

With regard to Pete's idle with those cams, I just happen to have a video of his car idling. (I'm not sure if Pete has ever seen this video!) That night Pete rode shotgun with his computer in his lap to do some data logging while I drove the car. I can testify that if it was short of low/mid range torque, I wasn't aware of it. As for WOT? That car is amazing!


Pete's car idling. (click on the picture to see the video)

The rattle you hear at the end is not the motor, but rather the ZF trans. It seems that even a slight roughness of the idle will cause the ZF to rattle. (If I recall correctly, Pete's flywheel at that time was a single mass Doug Rippie cast iron unit at ≈ 8kg (it now has a Ram dual disc converson clutch in it)

Oh, your English is just fine!

P.

[Pete]

Originally Posted by Toni94ZR1

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

My intakes are SGC stage III my exhaust is my own regrind master.
My Z does have a nice cammy idle like an old big block but drives like a stocker in traffic and pulls away nice from a stop,i always offer people to drive it.

Reason for small exhaust cam is, i have tested big exhaust cams before and after on big & small cube LT5's same results more low end power no sacrifice on peak power they tune drive drive much better.
All of our fastest 10 sec Z's have .224 exhaust cams in them.


Timing you're safe with 114-108.

Pete

Your english is just fine.

[Toni94ZR1]

Originally Posted by Paul Workman

Lee...like Brett said! CongratZ!!

Toni,

With regard to Pete's idle with those cams, I just happen to have a video of his car idling. (I'm not sure if Pete has ever seen this video!) That night Pete rode shotgun with his computer in his lap to do some data logging while I drove the car. I can testify that if it was short of low/mid range torque, I wasn't aware of it. As for WOT? That car is amazing!


Pete's car idling. (click on the picture to see the video)

The rattle you hear at the end is not the motor, but rather the ZF trans. It seems that even a slight roughness of the idle will cause the ZF to rattle. (If I recall correctly, Pete's flywheel at that time was a single mass Doug Rippie cast iron unit at ≈ 8kg (it now has a Ram dual disc converson clutch in it)

Oh, your English is just fine!

P.

Thanks Paul, I'm happy you understand what I write. I will keep on studying english.

Great video, Wow sounds amazing ! No rough and high speed idling, I love this sound, now I can see regrinding cams it's a must when do full porting to get the maximum of a 350 stock bottom at an economic price $$$$.

SGC stage III inlet cams and regrind exhaust cams, as Pete have, will be the best but may be are more expensive.

My brother Z have a Fidanza flywheel , not a stock dual mass, and the ZF trans do the same sound. Maybe Bill Bodreau (zfdoc.com) knows how to minimize or eliminate this rattle when a single mass is installed.
Toni.

[Toni94ZR1]

Originally Posted by Pete

My intakes are SGC stage III my exhaust is my own regrind master.
My Z does have a nice cammy idle like an old big block but drives like a stocker in traffic and pulls away nice from a stop,i always offer people to drive it.

Reason for small exhaust cam is, i have tested big exhaust cams before and after on big & small cube LT5's same results more low end power no sacrifice on peak power they tune drive drive much better.
All of our fastest 10 sec Z's have .224 exhaust cams in them.


Timing you're safe with 114-108.

Pete

Your english is just fine.

Thanks Pete, I'm happy you understand what I write. I will keep on studying english.

SGC stage III inlet cams and regrind exhaust cams as you have how much will cost?
And will be a must siamesed IH to get the best of this cams, plenum is already siamesed and IH and head ported to 36'5.
Toni.

[Toni94ZR1]

Originally Posted by Polo-1

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).

Yes Polo-1, chevy type 6.00 in rod better, less bore side loading.

I did different stroke combinations based on stock crank.

PDF: LT5 stroke pdf document

Knowing desired rod length and bore I found the piston compression height (CH) and displacement.

6 in. rod need a 1,18 CH piston, this is easy to get so a 6 in. rod are better and less side loading, CP Pistons have this 1,18 CH pistons as a standard product on different bore size and only need little modifications on desired dish and valve relieve machining.

5,85 in. rod need a 1,33 CH piston, maybe less options on the market.

To get a 411 ci on stock crank you need a 4,226 in. bore, this engine allow this big bore ? ,liner’s wall will be like a smoking paper.

Doing a stroke engine with stock crank, bigger bore, will need block bottom liner support machining to fit bigger liners, isn’t it?

382 ci engine need 4,075 bore, isn't it ?

Toni

[tpepmeie]

Toni,
Since you quoted my engine in your sheet, I am actually running 1.035" compression height. The piston is slightly out of the bore (0.010) at TDC.

P.S. You think Pete's idle is cammy. I'll try to post a vid of the 427. Sorry I missed BG this year, guys. Issues.

[tpepmeie]

Forgot to mention, at much less than 1.05 CH it becomes hard to get enough dish depth to run reasonable compression. My combustion chambers are opened a lot (+9cc), so that made it possible for me to run 12:1.

[Polo-1]

Originally Posted by Toni94ZR1

Yes Polo-1, chevy type 6.00 in rod better, less bore side loading.

I did different stroke combinations based on stock crank.

To get a 411 ci on stock crank you need a 4,226 in. bore, this engine allow this big bore ? ,liner’s wall will be like a smoking paper.

AES BIG BORE 4.165 $$$

Doing a stroke engine with stock crank, bigger bore, will need block bottom liner support machining to fit bigger liners, isn’t it?

LA Sleeve drop in up to 382ci.

382 ci engine need 4,075 bore, isn't it ? LA sleeve 4.010

Toni

Stock crank is offset ground. you end up with a small chevy rod journal 2.00
The stock stroke is 3.66 when ground it ends up at 3.75. It can be pushed out to 3.80 on smaller Honda 1.890 journal. I have not done this yet. Crank guy said lot's of meat in the LT5 crank to cut. The BIG Bore is from AES 4.165
The cheap stuff is to keep it down to 377-382ci mostly off the shelve stuff.

[Toni94ZR1]

Originally Posted by tpepmeie

Toni,
Since you quoted my engine in your sheet, I am actually running 1.035" compression height. The piston is slightly out of the bore (0.010) at TDC.

P.S. You think Pete's idle is cammy. I'll try to post a vid of the 427. Sorry I missed BG this year, guys. Issues.

Hi Tood, I read your great article about The Ultimate LT5 several times, this is a 4 pages article that have more technical information about LT5 than any other LT5 literature.

What I like in your article are that you said the reason you choose every internal part of the engine and every modification done, the conclusions about the engine running test are also very interesting.

1.035" CH pistons and 0.010 out of bore was the only information missing in your great article

I thought would be a cammy engine but I can see, in Paul video, it sounds like my brother stock LT5.

Yes please I'll be waiting your 427 vid

Toni