So... What about an LT1 based 302? (Page 2/3)
cvxjet SEP 12, 12:52 PM
A lot of people just assume that big American V8s were always slow turners (Basically).....Back in the early 60s the popular racing was stock cars, so Chevrolet, Ford and Chryco all built production V8s that were based on the setups used there; These engines (Chevy 348/409, Ford 406, etc) were HP rated at 5800 to 6000 rpm!

The Ford and Chevy 302 Trans Am engines were rated at approx' 290 hp stock at 5200- but with headers and a super tune you were probably going to see over 350 hp at 6000 plus RPM.

An interesting bit of info; The new Ford Coyote engine has 4V heads (Obviously) but the 1969 BOSS 302 heads (Basically 351 Cleveland 2 valve heads ) breath BETTER on the intake side! (The exhaust is bad because of the turn required to clear the spring towers in the old Mustangs)
La fiera SEP 12, 03:15 PM
https://youtu.be/OGIz5AZbwrU

NOTHING sounds like a SBC!
Will SEP 14, 10:05 AM

quote
Originally posted by Raydar:

I've been thinking about this for a while. (Not like I'm going to run out and do it, or anything. )

The Gen II smallblock, aka LT1, LT4, etc, uses a 4" bore block.
There is a 4.3 liter engine based upon the same architecture, that uses a 3" stroke.

Why not an LT1 or... even an LT4 based 302, utilizing that architecture?

Yeah... I know about the LS engines - especially the LS4 -, and I know about the "gotchas" associated with the LT1 Optispark, but it just seems like it might be a cool, unique thing to do.
Moving the power band up in the rev range will help to save transaxles, and the high revving nature of a 302 would seem to suit the Fiero's character better.
This is all based upon the premise that everything in the engine is built to support the high RPMs that would be expected.

Anyone?



The L99 (cast!) 3" stroke crank will fit any one-piece rear main seal Chevy block, so using the Gen II block/architecture is not necessary.
If you can use the Gen I block, then you can use a 4.125 bore and have a 321" Chevy that's even more oversquare.
The greater "overlap" of the main journal with the rod journal as a result of the short throw makes this crank significantly stronger than a cast 350 crank.
There are 6.385 BBC rods cut for 2.100 rod journals to decrease surface speed on high RPM BBCs. Using these rods will get you a rod ratio >2:1.
That assembly goes together with the same pistons as a 383 or 400 with 6" rods would use.

As was said above, de-stroke does not mean more RPM. To spin a Chevy (or any pushrod engine, really) to 8000+, you'll spend as much money on the valvetrain as you do on the rest of the rotating assembly.
Modern aftermarket cylinder heads flow well enough to make absurd power... 500-600 naturally aspirated in a street engine is possible. Think about how fast you'd have to turn a small engine to take advantage of that airflow... you quickly get to a point at which a larger displacement engine makes much better $$$/horsepower sense.

The LS engine family can build a similar engine in by using the 6.0 or 6.2 block & pistons with crank and rods from a 4.8. The 4.8 has an 83mm stroke. GM never built a LS with 3" (76mm) stroke, so an LS crank with that stroke would be a custom piece. I may have seen one on the market at some point.
gatorfrey SEP 14, 11:53 AM
Just for giggles, as I have been watching this thread.

The LS4 crankshaft is a little different on each end, as I understand. So, does someone make destroked, or 4.8 cranks, that will drop in an LS4 block.
(forged crank for 5-600 horsepower engines )
I ask as the point of using an LS4 block is a F40 trans axle fits it directly.
Also, what about Darton sleeves in an LS4 block. Any reason why not?
Yes, cost would be high. But I would like to know if it can be/has been/ done.
A destroked engine would move the power band higher, all things the same. But that would be not such a big deal in a FIero. Maybe a little easier on the F40, unless you jump in that power band range right off. A takeoff with less torque and horsepower would not be a hindrance moving a light Fiero,right?

Or just put a regular LS block in it and make a combination bore and stroke?
cmechmann SEP 14, 06:42 PM
If you can find one.
But I had always had liked the Buick small block. The engines that the Buick 3.8 was based off of. I have taken water pumps for the 3.8 and installed them on Buick small blocks. That I could tell. The timing cover and a lot of the internals were interchangable between the 300V8 and 225V6.
I had a stock 1964 Buick 300(310) V8 in a Chevy LUV truck. It would take RPMs over 8000 without issue.
The Brits love the 215 aluminum V8. There are a few different versions. The Buick 215 had issues with head gaskets. The Olds version had 5 head bolts per cylinder as Buick had 4. The Olds design, went on to become the V8 that Land Rover used for almost 3 decades. Their later ones had bad cast. It used the round bell housing style that GM used up to 1963.
However there was the aluminum 215 2bbl, 4bbl, round bell housing, BOP bell housing, 4 head bolt, 5 head bolt.
300 came a few different ways 2bbl, 4bbl, up to 1963 round bell housing, 1964 and later BOP bell housing. All cast iron or cast iron block with aluminum heads.
Then there was 1965-1967 340. That I know of it only came in the GS(grand sport).
These were used in Buick Special, Century, GS. Olds Cutlass, F85. The 300 was also used in GMC trucks. Saw a few in school buses.
2 known issues. Hard on valve guides(but you would reman them anyway). Also the oil pumps were very dependable but did bring up pressure slower then submerged pumps. Free reving with no load, spinning them up cold. could damage bearings. However this is still applied to the 3800 even after getting a gearrotor in the timing cover.
Other than that they would take punishment. Just on the 300 I had. I had the Special that the engine was in. Bought from someone for $50 in 1980. The guy said that the engine had been gone through about 80,000 miles before they let it sit since about 1974. It had mud about 1/2 full in the starter. Cleaned every thing up and fired it up. Then the Flinstone floors(see through) were too bad to drive it anymore. Mom had a LUV truck setting in the drive way. This was after 2 of my brothers tried to use it to tow a 1965 Barracuda and fried the engine. So the 300 went in. Drove it well over another 100,000 like that. I was brutal on that engine.
It just seems that, that would be a sweet engine for a Fiero.
OldsFiero SEP 15, 07:49 AM
It's been done.
Raydar SEP 15, 02:22 PM
Heh... Interesting how this has evolved.
Lots of good advice and good info here.
And yeah. I get it. High revs require expensive valve train bits, among other things. This was merely a "what if" proposition.


Since were talking about expensive, impractical stuff... I'll mention that, a few years ago, I saw a non-GM SBC race block that was designed to fit LS heads. I posted it in another thread here, but I'm pretty sure it's no longer available. If, indeed, they ever sold even one.

Please continue. I'm enjoying the read...
Blacktree SEP 15, 02:37 PM
Just as an aside, I'd like to do something similar with an LS based engine. For example, mod a 5.3 to turn 9k RPM. They can already handle 7k RPM stock, which should make things a bit easier. Maybe one of these days...
Raydar SEP 15, 07:21 PM

quote
Originally posted by Blacktree:

Just as an aside, I'd like to do something similar with an LS based engine. For example, mod a 5.3 to turn 9k RPM. They can already handle 7k RPM stock, which should make things a bit easier. Maybe one of these days...



Now that's something way more practical that what I was thinking. And it's not even based on the state-of-the-stone-age art.
Will SEP 16, 09:33 AM
One thing to keep in mind is that with the valvespring requirements to turn that RPM, you'll basically need aftermarket cylinder heads, as the loads stand a real chance of breaking a rocker boss off a production head...