School Me on LS Motors

[Road Trip]

Here's a clip from Road Atlanta several years ago when my 24 Hours of Lemons team's E36 BMW lost the clutch. I was driving the whole track in 4th gear, so I came out of the slowest corner way low in rpm, but then came up on cam on the straight. Once the engine hits 6000 rpm you'll notice that I hold it there for fifteen seconds. That's 6000 rpm with the motor pushing a 3000 lb car at 120 mph. Our team did that, lap after lap, all day. The motor had aftermarket springs and overhead cams, but I also give credit to BMW for the build quality.

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Hey Erik,

Some time ago I watched this very video during one of my
'Oops, I've reached the end of the internet' expeditions.

I feel like I'm hanging out with Robin Trower talking about
his Bridge of Sighs album. :0) Nice video, especially liked
all the data superimposed on the great windshield vista!

Then it got money-shifted to 10,000+ and all the valves looked like this.

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Q: Was it only the exhaust valves? Or all of the exhaust valves plus a
handful of intakes? Or were both intake & exhaust valves all bent?
(I have a theory that your answer will prove/disprove.)

Yeah, all of the above just adds credence to your desire for
long-term reliability vs. peak peak power. When you are
spec'ing out your cam to the cam guru, no doubt he will
want you to run a more valvetrain-friendly lobe shape
(that only gives you 97% out of theoretical 100) vs.
a max-effort 100 out of 100 lobe that's more suited to
a car that competes 10 seconds at a time at the local
dragstrip.

Neat stuff!

 

[Erik the Awful]

It's been eight years or so, but I think we bent every valve, exhaust and intake. It's an M52, and when it got money-shifted the tach wrapped around pretty far. Makes for interesting video, but it's not on the web. The clutch was working-ish again and the driver was at the top of third and accidentally grabbed second instead of fourth.

 

[Erik the Awful]

To summarize, back when Ford wanted the GT40 to last the full 24 hours as well as beat Ferrari
at their own game, the overriding rule was for the drivers to adhere to a strict rpm limit, despite the fact
that the engine was capable of more on the dyno.

Being the primary guy to turn the wrenches, I always tend to run a bit shy on the rpm compared to the others. I'm usually down about a second a lap, but I can run 20 minute longer stints because I conserve so much more fuel.

In answer to @PlayingWithTBI's "recommendation", the stated goal was literally to build an 800 hp engine and run it at 650 hp. It's just out of the question for a naturally aspirated stock stroke LS.

 

[Road Trip]

It's been eight years or so, but I think we bent every valve, exhaust and intake. It's an M52, and when it got money-shifted the tach wrapped around pretty far. Makes for interesting video, but it's not on the web. The clutch was working-ish again and the driver was at the top of third and accidentally grabbed second instead of fourth.

Well, since you showed me your money-shift I'll show you mine:

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* Did that all by myself.

* Instantly regretted it.

* In milliseconds I deleted 2nd gear & replaced it with a 2nd neutral location.

* Limped it home from the scene of the crime in 4th. Sounded like someone
had filled a blender with ball bearings and set it to Liquify -- just like the old
Batman show on TV: BANG! CRUNCH! SCREECH!

NOTE: Every few seconds the rear tires would lock up/skid and then resume.
I'm assuming that this was FOD attempting to enter remaining teeth between cluster gear
and the remaining gears that meshed with it. But it kept clearing & I continued on my way
jerking back and forth behind the wheel. (Obscure Devo song reference. :0)

* The Cologne plant had a fire, so I had to wait ~6 weeks for the parts to come in.
(I worked with good friends, so I got to work reliably & kept my after school
landscaping job.)

* This photo was taken years later. I cleaned it up & keep it on my desk to remind
myself that pushing equipment to 9/10 makes much more sense than 11/10.

* The trans had a cast iron case, which shrugged off the incident. This 4-speed became
my first ever manual tranny rebuild. The parts set me back a cool $178 back in
the late '70s. (A small fortune at the time.) But I had no choice, for the
junkyards wanted a mind-blowing $350 for a used one. "All speeds guaranteed to
work, synchros as-is." Yikes!

* With brand new cluster gear, new 2nd gear, new 3rd gear (collateral damage, 1
tooth missing) all new synchos, new needle bearings, & a selective shim kit...
it was completely quiet, smooth, and shifted like butter. (Thank you Mr. Laramore
for leading me through my first rebuild...a mentor like that is priceless!)

"That's all I have to say about that." -- F. 'Road Trip' Gump

 

[PlayingWithTBI]

The trans had a cast iron case, which survived the incident.

Yeah, BTDT with a Borg Warner T10 in my 63 Chevy. The main reason I ran one over a Muncie M21. The Muncie's aluminum case would usually scatter too.

 

[RDF1]

Ive never been around any of the endurance style racing. 99.99% the stuff i deal with is either Daily driven Turbo LS trucks or Drag racing vehicles.
Stock Gen 4 5.3 with Johnson 2110R lifters, .700" Dual springs, and the right cam with a big ole turbo we had it leaving at 6000rpms with 18psi boost on the transbrake. Shifting it at 8900-9100rpms on 44# boost. That was the coolest sounding setup and was silly fast. It lasted almost 3 seasons running mid 4s in the 1/8 mile. It would rev from 6000 to 8500 before the 60' and boost ramp from 18 to 44psi in less than 1.2 seconds..

 

[Erik the Awful]

While we love boost, it adds a level of complexity to endurance racing. Turbos add heat, and we don't have time to cool it down. It has to cool while still racing. Turbo oiling is critical and has to be bulletproof or you can injest metal bits into the engine and end your weekend. You also can't fix a boost leak by tightening the clamp and praying it holds for another run. It has to be resolved. Hence why we're starting with a naturally aspirated V8 instead of a much lighter motor boosted to the moon.

Endurance racing is an engine punishment that doesn't end. Imagine making a thousand dyno pulls back-to-back with no wrenching and expecting the engine to be in similar running condition when you are done than it was when you started.

 

[0xDEADBEEF]

The LS has won the Rolex 24, 12 Hours of Sebring, and the 24 Heures du Mans.

 

[RDF1]

yea like i said, ive never been around any endurance racing.
Id imagine large oil coolers and such are needed to keep it all under control.

I was looking back and found a LS3 car that put down 480rwhp on the dyno with just a 227/237 cam and 1 7/8" headers. So roughly 570 Crank HP going by parasitic loss on dyno and fuel flow numbers from injectors.

To get the hp number at lower rpms you would need a 4" crankshaft. I dont see anyway around that for a N/A setup.

I would like to try a 388CI and see how that does. 4.125 bore x3.622 stock crankshaft.

 

[Erik the Awful]

I found this article the other day. It's a bit old, but it narrowed my search a bit.

https://helpcenter.jegs.com/hc/en-us/articles/115012012407-Junkyard-LS-Engine-Builds

Our prime candidates for engines are LQ9s or LY6s. Currently our goal is to keep the bottom end stock and unmodified other than new bearings and ARP rod bolts. The LQ9s have a 10.0:1 compression ratio. The LY6s have a 9.67 compression ratio, but came from the factory with the L92 heads. The L96 is also a contender, but it's newer and harder to find cheap.

Actually finding the engine is another matter. I'm going to have to beat the bushes and pester friends to see if anyone knows of an engine for sale. Here in Oklahoma it's a seller's market for trucks and truck parts. Complete engines with harnesses and accessories are $1500-$2000. The heavy duty trucks that have these engines command a premium, even wrecked.