SAM/CH ZR-1

Whenever you disassemble your engines, check the timing chain guides. It's very important. This one ask for replacement.

oldpro

did you make your plenum gaskets or did you buy them that way . I have similar porting on my inj housings and plenum

SAM/CH ZR-1

I bought and adjusted them.

WydGlydJim

Sam, can you post some links to your work, your shop, your accomplishments, projects you have been involved with.....I am interested in what is happening in other countries.....I tried to find some stuff via searches, but it did not seem readily available?

SAM/CH ZR-1

Jim,
I do not have a official website because I do work only in my spare time with LT5's like many enthusiasts here do too.
There are different projects I work on like 373, 391, 394, 427 and 433 upgrades, a better cooling system and how to make the Tremec Magnum transmission fit. I like the shorter 5th and 6th gears. Also I do support and consult a LT5 racing team.

Here a little idea for more airflow:

SAM/CH ZR-1

A high performance piston manufacturer in Germany did within 2 weeks a new one. All parameters are the same. Now the engine assembling can start.

Rkreigh

are those Mahle pistons?

they seem to make some excellent products.

Like to hear more about the tranny conversion. I love my ZF box but clearly the gearing isn't ideal.

nice valves! what do you think of the AES liners for more of a "closed deck"

I'd love to do a stroker LT5 with the deck plates like fastlane did, custom stretched liners, chains, and a 427 displacement with my current crank and ti rods

I think it would be a more potent combination with much more torq

glad to see John's old car get some love. I saw it in the late 90s, so it decline, gibby bring it back from the dead, and now some upgraded internals and freshen up the engine.

are you staying with the jeal cams? they look ok?

thanks for all the pics and progress updates!

SAM/CH ZR-1

Hello Ron
Actually I wanted to send the piston to JE to make a new one. Unfortunately it would take about 2 months to duplicate and I would have to take at least a set of 4. I didn't want to wait that long. Just 5 miles away from me, but in Germany, I found thanks of a friend's advice a high performance piston manufacturer. They do all kind of pistons for different applications. It was not a problem to do just one. The first piston they did was 10 gramms leighter, so they had to do another one. Now the weight is perfect.

The tranny conversion is a interesting project. The Tremec Magnum has nearly the same size and weight like the ZF, but it can handle with a torque of 700 lbs. In combination with Jerry's dual disc clutch and a 18 or 22 lbs flywheel it should work perfect and reliable for the big cubic inch motors. A Tremec is also easier and cheaper to repair. I've read the synchron rings are made for shifts up to 8'000 rpms.

I spoke with a company in Texas who can do a bellhousing for a LT5 with Tremec Magnum transmission. They ask 1'300 Dollars for this part. A bit pricey. If somebody of you guys have a idea where the bellhousing could be bought cheaper, let me know.

The ZF Transmission is good for stock or slightly modified engines. But when it's about a significant torque increase like the 385's and bigger engines have, then it reach its limit.
I've been told that the ZF S6-40 6-speed is basicly a 4 gear transmission with 2 additional added gears. That can explain why especially the 6th suffer and can overheat under permanent load when you for example drive the car for a long time with a high speed above 120 mph. The 5th can also overheat. When you lower the car the transmission cooling become worse.
For the price you pay to overhaul a ZF completely it maybe would make more sense to switch to a Tremec.

The thin stem inlet valves are for my own 433 engine project. I have a set of ported cylinder heads with bigger inlet and outlet valve seats. They do flow 345 cfm at 0.450 lift. These 40.6 mm valves should increase the flow additionaly.

When I was going to build a new engine for myself I saw the site of AES and noticed they advertise their liners can go with a bore up to 4.165 inches. I've got the crazy idea to build a 4.165 x 4.165 LT5 which would be a 454 cui displacement. A hommage to the old 454 big block Chevy engine.
I spoke with a guy from AES and it turned out that he don't trust much in their advertised 4.165 bore. He was not sure if the liners won't break. From this moment my 454 cui LT5 idea died.
I looked then for another combination. My main goal was to go with the maximum possible cubic inches under the aspect of reliability and durability.
It was clear my engine will run with pressed in liners and 6 inch rods. I wanted to order a closed deck block from AES but obviously the gentleman there didn't see it as necessary to answer on my email request in a usefull time.
So I did place meanwhile my pressed sleeves block order (open deck version) to a guy in Lousianna.
We go with a 4.125 bore and a 0.050 offset 4 Inch crank and 6 inch rods.
The "closed deck" version is not bad I think but what when you have a issue with a liner? Who can fix it? I believe when you run a big cubic inch LT5 with Marc Haibeck's MLS head gaskets the liner moving stability increase. For what you need then a closed deck block? It maybe make sense when you have a big stroke and short rods.

Fastlane did a awesome engine. If I am not mistaken it run with 6.25 or 6.5 Inch rods. For a race car OK, but to expensive for a daily ZR-1 driver.
The theory says with longer rods the piston stays a bit longer at top center. The additional time helps to increase the fuel detonation pressure and torque. It can be. I like the longer rods because of better rod angle and less piston side load. The big 4.125 bore is great for faster trottle response and velocity in the ports.

Gibby's yellow car is really interesting. I like the custom made exhaust system with DynoMax exhaust valve mufflers. While cruising the car is not loud but when you push the pedal down it scream.

Jeal's cams looks fine. No issues. The same about the lifters. No extraordenary wear. As mentionned in my previous post I will replace all valve lifters with lighter ones and leave the cams in. The car did not run bad but under its potential due to strange porting works and other issues.

Sam

5abivt

Very cool and thanks for sharing your experience One day I want to build the Lt5 for my car so Im still learning many things. Mind if I ask about the lifters and which ones you will use? How much weight will they save? Are the valves you are using hollow stem?

I did just build an LT4 for my 93 non zr-1 car and its a lightweight theme. I ran a 3.625 lightweight crank, 6.2" rods with mahle pistons. A custom cam for a unique firing order with hollow valves and a lightweight lifter setup (solid roller). If I built the LT5 I want to do a 3.625 with as big of a bore as possible with all lightweight components and a really long rod for all the reasons you stated above.

As for the Zf 5th is a partial overdrive yes but durable as the others for wot from what I know/believe. 6th is for fuel economy and light throttle and I did blow up a zf myself in my 93 15 years ago because it had 4.09 rear gears and I was using 6th for top speed runs and lots of wot.

Jagdpanzer

Excellent work Sam!
You are a inspiration to all of us of the LT5 persuasion who are searching more power from this fine engine design without compromising it's reputation for durability or reliability. I'll be working over a set of heads this winter and also interested in learning more about the larger valves you are going with on your 433 CID engine. Can you please tell us more about the valves, seats, and guides and where you sourced them?

SAM/CH ZR-1

The valve stems are not hollow.

About lifters weight difference look at the attached pictures:

tpepmeie

There's a VW/Audi cam follower that is the same weight. Made by INA. I don't have the part number handy. 034 109 309

SAM/CH ZR-1

Thank you.
The LT5 is not a engine. The LT5 is a passion with potential and some hidden secrets.

The heads including bigger valve seats I purchased from ACS Vette in Lousianna. The custom made inlet valves, guides, seals, valve spring caps etc. I've bought from South Georgia Corvette.
The special cams will be manufactured in Sweden. Over the coming winter I do assemble the engine.

appelen

Hi Sam,
For bellhousing you should be able to use a LT1 F body 93 -97 that fits the Tremec but you need to relocate one bolt hole on the bellhousing, if you look at the engine from behind the bolt at approx 2 o clock needs to be moved about 5/8" and you can use all the f-body clutch assemblys, hope it helps.
Alf

SAM/CH ZR-1

Alf
Thanks for the advice. I will try one.

Sam

SAM/CH ZR-1

Previous ports vs new ports with a bigger secondary flap.

Sam

SAM/CH ZR-1

I wouldn't buy or use them.

Sam

GTB/ZR-1

Great stuff, Sam... Thanks for sharing all of this w/ us.

FU

Can I ask why not ?

SAM/CH ZR-1

Hello Frank

Because it's 2nd class material. These part number lifters use to fail after about 15'-25'000 miles. It's what I've heard from other guys who used them.

Sam