LS4 build

Real tech discussion on design, fabrication, testing, development of custom or adapted parts for Pontiac Fieros. Not questions about the power a CAI will give.

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FieroWanaBe1
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Re: LS4 build

Post by FieroWanaBe1 »

Well the flat top pistons and rods were sold to a coworker, just need the cash at the moment. Ill be going the route of forged 6.125 rods and forged pistons in the future. Right now im going concentrate on getting the motor rebuilt on my '84 SD4 car.
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FieroWanaBe1
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Re: LS4 build

Post by FieroWanaBe1 »

I took a chance, and bought RPM Int. Forged I-beam Rods for the LS4 in 6.125" length. They weigh 603G, claim to be 4340 Steel, and claim to have have 7/16" ARP-8740 hardware. I did as much research as I could. And stock Gen IV is probabaly the best to use for up to a 500-600HP build. I have been making a conscience effort to lighten everything I could in the rotating assembly without spending a fortune. I will order the forged JE pistons soon.
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The Dark Side of Will
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Re: LS4 build

Post by The Dark Side of Will »

Uh oh. Shit done got serious.
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Shaun41178(2)
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Re: LS4 build

Post by Shaun41178(2) »

Anything new?
FieroWanaBe1
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Re: LS4 build

Post by FieroWanaBe1 »

Nothing at the moment.
I went Active Duty for the guard for the next two years, and took a cut in pay from my day job.
I was going to pull the trigger on the JE SRP pistons for the 6.125 rods before all this happened. My car parts and cars are all wrapped up and in storage, including the LS4 and SD4.
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The Dark Side of Will
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Re: LS4 build

Post by The Dark Side of Will »

Did you find some cool orders you couldn't pass up?
FieroWanaBe1
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Re: LS4 build

Post by FieroWanaBe1 »

Something like that,
Went for a change in military occupation, Its been a long road to get accepted, and now the training pipeline is even longer.
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The Dark Side of Will
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Re: LS4 build

Post by The Dark Side of Will »

Cool. What are you going from/to? Taking advantage of that pilot signing bonus?
FieroWanaBe1
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Re: LS4 build

Post by FieroWanaBe1 »

No piloting for me, I lack the color vision needed. I was a wheel mechanic for 10 years in the Reserves, I moved over to the Guard a few years ago to train up for something more exciting and demanding. I don't need to get into it too much, it might not work out. But if it does, it might lead to other, even more exciting opportunities and big signing bonuses.
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FieroWanaBe1
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Re: LS4 build

Post by FieroWanaBe1 »

Hopefully my first tube cradle will be built this summer.
Ill be working on the design a bit more this winter.
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Tube Cradle
Tube Cradle
Screenshot 2021-02-11 142341.png (233.6 KiB) Viewed 4498 times
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The Dark Side of Will
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Re: LS4 build

Post by The Dark Side of Will »

Good to hear from you again.
Solidworks?

I've been eyeballing Blooze' drawings, and it looks like I could fab a cradle from large laser cut pieces and not miss much.
FieroWanaBe1
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Re: LS4 build

Post by FieroWanaBe1 »

Yeah it was done is Solidworks using Blooze's measurements.
Blooze sent me some data to model a long time ago, and I've only ever nibbled on his measurements from time to time, its a lot of complex metal formed pieces.
Laser cut and bent pieces could easily replicate 90% of the factory cradle, less the factory exhaust routing and clearance bits.

I have access to tube bending and notching equipment, and I have my hobby cnc-plasma. I think a tubular design can shed some weight, add some clearance, and I can make a jig for it so a few copies could be made.

I would like to reduce roll steer by bringing the toe link the pivots inboard and raise/lengthen both the lateral link pivots as much as practical.
And an adjustable anti-dive bracket for the longitudinal link would be great to add.

The knuckle itself would be great to duplicate to utilize an off the shelf larger wheel bearing. I have the rebuildable Jeep 5x114.5 bearings I think I want to use, since they are slightly future proof with standard bearing inserts, but the SKF C6/C7 X-tracker Corvette bearings seem very nice and stronger too, with less wheel options. I would really like to find some axle stubs for a 930 CV joint and move away from the tripot type axles.
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The Dark Side of Will
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Re: LS4 build

Post by The Dark Side of Will »

Since you mentioned C7 bearings...

https://www.driveshaftshop.com/domestic ... che-930-cv

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ericjon262
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Re: LS4 build

Post by ericjon262 »

I've given alot of consideration to building my own cradle. if I kept the 88 suspension pickup points, I would make the bolt holes for the lateral links 1/2" to allow for easier to obtain (in the USA) rod ends, without any kind of bushing. I'm considering trying to drill them out on the spare cradle I have, but the spacing would make that difficult.
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FieroWanaBe1
Posts: 427
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Re: LS4 build

Post by FieroWanaBe1 »

I have started acquiring some hardware for the build.
Mostly new GM performance MLS head gaskets, GM LS7 oil pan gasket for my LS3 dry sump setup, a new LS2 chain damper, new LS7 MLS exhuast gaskets, LS7 manifolds from a wrecked C6, a knockoff LS3 valley cover from Amazon/China, and and a thermostat housing:
https://www.amazon.com/dp/B0BF16ZDPN?ps ... ct_details

This is if I continue the path on the Meziere remote mechanical pump,
Other wise I bought some pump spacers:
https://www.amazon.com/gp/product/B09R8 ... UTF8&psc=1

I may see if I can modify and make the LS4 waterpump interact with the corvette crank pulley, I'm sure the spacing wont be correct but there are 1.5" spacers available off the shelf if I need something in between. This would tighten the packaging up a little bit more, and integrate the thermostat to that space.
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The Dark Side of Will
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Re: LS4 build

Post by The Dark Side of Will »

ericjon262 wrote: Fri Feb 12, 2021 11:14 pm I've given alot of consideration to building my own cradle. if I kept the 88 suspension pickup points, I would make the bolt holes for the lateral links 1/2" to allow for easier to obtain (in the USA) rod ends, without any kind of bushing. I'm considering trying to drill them out on the spare cradle I have, but the spacing would make that difficult.
I think pretty much everyone who's done that has gone with 5/8" or larger rod ends anyway... No need to swap to 1/2" bolts, although I do use class 12.9 12mm bolts and pull them to 80ftlbs
FieroWanaBe1
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Re: LS4 build

Post by FieroWanaBe1 »

I have been doing some research on what the consensus is on the maximum bore of a the Aluminum 5.3.

The best I can gather is results vary based on year of the block.
Gen IV Aluminum RWD 5.3 Blocks have siamesed bores. These can be dry sleeved to large bores.
Gen III Aluminum RWD 5.3 Blocks could maybe have the LS1/LS6 sleeve ODs and may be able to achieve a 3.9" bore, some may not. Some published numbers for all Aluminum GEN III blocks, 2000 and up is .010.

The LS4 Casting obviously differs in some ways from both the Gen 3 and Gen 4 RWD castings.
The cylinders are not siamesed, despite being a Gen IV small block. Because its a unique casting I am not so sure GM just gave it small bore LS1/LS6 liners as some people claim is the case with Gen III aluminum 5.3s.

I have confirmed with Steve and RED that the LS4 cannot accept a dry sleeve like other later 5.3 blocks.

So I checked out the bottom of my bores and can see what I believe is a cast in liner and the bare aluminum backing:
Screenshot 2023-08-23 085216.jpg
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My 06 LS4 sleeve has about .120-.150 of thickness at the base of the cylinder.

a .010 over bore steel leaves .115 min thick liners
I have read that the factory sleeves on other aluminum motors LS2 and LS7-Press-in are somewhere between .070 and .100, maybe around .080 according to the internet lore and libel.
I think I feel comfortable with running a .010 overbore, despite the GEN III "no more than a .003-.008 hone" rule.

A 3.900 bore would yield a sleeve diameter of .060 to .090, maybe too thin for my comfort, but people claim to have built aluminum 5.3 block, bored to a 3.9" bore (LS1/LS6).

here is a GM cross section of the original LS1:
SA86_FULLBOOK_LS1LS6_Page_018_Image_0001.jpg
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not very thick. this is where the .005 max overbore rule come from.

And here is the bottom side of a LSA Block:
dsc06416_3c6a6dfa71b0f54defcc025d570ee9eb9bd41157.jpg
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It may have ever so slightly thinner sleeves.

An this is hard to judge, but here is the bottom of a LS2 block. the sleeves do seem to be smaller than my LS4 by s a small amount
Screenshot 2023-08-23 094300.jpg
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I do think the .010 max bore rule may apply the LS4 block, but I don't think it would hurt durability any measurable amount, but in my opinion its a risk to run the LS4 at the LS1 bore size.
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FieroWanaBe1
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Re: LS4 build

Post by FieroWanaBe1 »

FieroWanaBe1 wrote: Thu Feb 11, 2021 3:25 pm Hopefully my first tube cradle will be built this summer.
Because I have been married now since this post for 2 years, my 9 to 5 is a 7:30 to 5, and I have to travel across the planet servicing and commissioning test stands on top of that, this wasn't built that summer.

But I have since snuck some time to add some mounting tabs.
Screenshot 2023-08-24 083800.jpg
Screenshot 2023-08-24 083800.jpg (83.87 KiB) Viewed 2912 times
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Emc209i
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Re: LS4 build

Post by Emc209i »

I feel like there's so many diminishing returns to building that. Why not just grab an 88 cradle and call it a day? (playing devil's advocate)
FieroWanaBe1
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Re: LS4 build

Post by FieroWanaBe1 »

I have an entire 88 suspension currently.
What I'm after is reduced weight, and altered geometry to correct for a lowered car, like raising the inner pivots.
This cradle would end up at about 35lbs welded with 1.75" OD .125" wall primary steel tubing. without mounts.

Making something out of aluminum I can see the weight being 25lbs (with larger tubing to increase rigidity)

If I recall, the Factory 88 Cradle weighs near 60lbs bare.
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