One Fast Ol' LT-1

In reply to Appleseed :

Isn't the D body essentially just a longer wheelbase B though?

tuna55 said:

 

Isn't the LT1 block just a wee bit better than the standard engine which came before it? I mean, if they are running block filler , a main girdle and stuff, it should be strong enough for that output, though not ideal in the long term.

It is a remarkably similar block casting to a traditional SBC.  In fact, the entire rotating assembly is interchangeable with a 1-piece rear SBC.  Cams have teeny differences since the distributor is driven off a pin at the front instead of a gear at the rear, but LT1s still have the distributor drive gear on the cam to run the oil pump off a "dummy" dizzy shaft in the back.

The big difference is in the deck and heads.  The water passages are completely different, but the swap has been done before with some welding/drilling.  I knew of one short run of Dart blocks for LT1, but I don't think it lasted very long.  Looking at the blocks, I really think they just took an SBC block mold and closed up the holes in the deck and re-drilled them for the LT1 heads.

Putting LT1 heads on an SBC is not impossible.  No one really ever did it because the aftermarket has so many heads that it is not necessary.  There was no reason for the average person to make the conversion because LT1 heads were very similar in flow to Vortec heads, and the aftermarket had tons of options.  However, it might be worth the effort for a racer like this one... they can get a Dart SBC block for the strength and rework the decks for the LT1 heads, therefore technically making it functionally equivalent to an LT1 if the class allows it.

A stock LT1 block with a girdle, block fill, and all the goodies will take 1300hp... but I don't know for how long.

Appleseed said:

Daylan C said:

In reply to yupididit :

LS heads are a bit taller, other than that they both fit in the same hole. Not sure on the weight but I know most LT heads are iron and most LS heads are aluminum.

All B-body heads are iron. All F-body and Vette heads are aluminum, including the LT4.

Quoting for truth, and I'll add this.

The F-body aluminum heads don't flow as well as the iron B/D body.  The ports on the iron LT1 heads were exactly copied for the Vortec heads because they were darn good.  The B-body was rated at 260 hp, and the F-body was 275.  In order to get that, they had to add several more degrees to the cam for the F-body.

Daylan C said:

In reply to Appleseed :

Isn't the D body essentially just a longer wheelbase B though?

Yes.  They are functionally pretty much the same, different wheelbase.  another example: Olds 88 and Olds 98.  The 98 was just a longer 88 and called a D body.

Appleseed said:

If recall correctly,  only the LT4 got 4 bolt mains. I know my 9C1 only had 2 bolt main caps.

 

All Corvette LT1s had 4-bolt mains as well. Supposedly OEM replacement short blocks all came with 4-bolt mains too, as well as some '97 F-bodies.

Daylan, you still have that L99?

In reply to BoostedBrandon :

Yes, still here.

In reply to Daylan C :

Damn. I was just in Smith's Grove this evening and thought about it.

Damn damn damn.

I gotta think that this thing really causes some hurt feelings. A lot of the guys he's running against are running LS engines with aftermarket blocks that can have a whole lot of cubic inches (427s seem to be most common), crazy rectangular port heads that outflow traditional SBC race heads, and wild high-rise billet intakes. And this guy is faster than them with a production block with less displacement, a production intake manifold and heads that probably flow a good bit less. 

In reply to NickD :

A lot of the guys he's outrunning are making noticeably more than 1300hp.

In reply to Daylan C :

Yeah, I know Leroy is making ~1500whp. Also, on paper, that car should have a weight advantage, being a 'Vette kart, but it's surprisingly heavy. I imagine the aero deficit hurts them too. But some of the other car's he's outrunning are 'Vettes, and I can't imagine a 4th-gen F-body being that much lighter or aerodynamic than a C5 or C6 Corvette.

The aero on the vette kart is atrociously bad. They have a wind tunnel testing video of that car that was interesting. 

Vigo said:

The aero on the vette kart is atrociously bad. They have a wind tunnel testing video of that car that was interesting. 

yes the video about the wind tunnel testing said they needed 545hp at 170mph to overcome the air force.. Leroy's Drag coefficient is 0.74  https://www.youtube.com/watch?v=1X35-bGWpEY

Leroy was last weighed on video at 3000lbs at raceweight with Cleetus in the car.  They then went to a methanol mix, removed most of the water system and put a small radiator in so he likley is at 2900ish lbs with cleetus in the car.

Also the Driver Mod in leroy is the big factor as well especially in a stick car.  iirc Cleetus is a really good driver for stick shift drag racing. Like he had the fastest pass in SketchyVert in 2016. On his first pass ever running the car he ran a 10.28 while the owners fasted pass had been a 10.60.

In reply to MrChaos :

It's amusing watching Garrett make a pass in the C6 with a powerglide. He gets a "what do I do with my hands?" look on his face.

Driver skill and chassis tuning are often overlooked when people are simply chasing dyno numbers. Not only does the engine make the numbers, the chassis knows what to do with them, and the driver knows how to  control the chaos.

Daylan C said:

In reply to MrChaos :

It's amusing watching Garrett make a pass in the C6 with a powerglide. He gets a "what do I do with my hands?" look on his face.

I prefer James' eyes wide open, slightly terrified expression. James is my favorite part of Cleetus videos

In reply to NickD :

"I dunno, if james gets a hold of a boost controller..."

"There's a reason I didn't buy wastegates."

They should have kept the B-body and updated it for one more gen by giving it the Vortec 8100 motor.

In reply to Dootz :

No offense, but why? It made 340hp, which is barely more than the F-body LS1 and less than the Corvette LS1. Sure, it made more torque but it was also massively heavy. I know that Tim Allen did build an LT5 Impala SS, and that thing had to be pretty awesome.

In reply to NickD :

The torque management is pretty heavy on the 8.1L, in marine form it was 375-415 hp. A good tune will increase the power even more. Still not the best engine for a car, better for trucks. A Gen V LT4 would be a hoot in a B-body wagon though.

I do like the Gen 2 LT1/LT4, enjoyed driving the 95 Trans Am I owned. Good low to mid-range power for the time. Glad to see they are still being run out there and doing well.

Here's to hoping the used market for LS' and the truck variants start to come down to more reasonable prices because of this?

....

Please?

Also, does anyone know which T56 he's using? The older LT version or the newer one?

FuzzWuzzy said:

Also, does anyone know which T56 he's using? The older LT version or the newer one?

I'm pretty sure that internally the T56 was the same between the LS and the LT, the only major differences being the bellhousing pattern (The LT has the old SBC pattern, the LS has the LS pattern) and I believe the clutch assemblies. He's still using the LT bellhousing, but the transmission has been all overhauled internally and slick-shifted and he's using some sort of crazy single-disc slipper clutch (Black Magic is the brand I think)

the only real difference is the bellhousing, front plate and input shaft.