So... What about an LT1 based 302? (Page 3/3)
darkhorizon SEP 16, 01:17 PM
The limits of your RPMs are not that related to the displacement or stroke or rod length, its more related to your heads/valves. Just because you have a 5.7 over a 5.0 does not mean there are any issues with spinning it at 7500rpms.... My stock LS2 is a 6.0 and shifts at 7200 commonly with plenty of valve float over 6500, lol.
Will SEP 16, 01:25 PM
500 CID Pro-Stock engines turn >10,000 RPM and 800 CID "Mountain Motors" with 6" strokes turn 8500 RPM.
Reborn756 SEP 16, 01:49 PM
Just thought I would weigh in here, because I had a similar idea with my last 3rd gen Trans Am. If you can find an L99, and by L99 I mean the LT1 based 265ci engine, you can pull the crank and rods from it and drop it right into an L98 block. Upside to the L98 block is HEI instead of that dang optispark. Should make quite the screamer, and from the the research I did, the PM rods used in the L99 should hold up no issue to the RPMs you could reasonably turn. Could always have a custom forged crank and rods built for the combo, but break out your wallet!

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- Darryl

FieroWannaBe SEP 16, 02:38 PM

quote
Originally posted by darkhorizon:

The limits of your RPMs are not that related to the displacement or stroke or rod length, its more related to your heads/valves. Just because you have a 5.7 over a 5.0 does not mean there are any issues with spinning it at 7500rpms.... My stock LS2 is a 6.0 and shifts at 7200 commonly with plenty of valve float over 6500, lol.



The cam/head combo ( with a valvetrain that can move that quickly)from your LS2 on a 5.3L, or 4.8L (if it where to fit) would produce its power peak at a higher RPM due to the different displacements.
Blacktree SEP 16, 07:33 PM

quote
Originally posted by FieroWannaBe: The cam/head combo ( with a valvetrain that can move that quickly)from your LS2 on a 5.3L, or 4.8L (if it where to fit) would produce its power peak at a higher RPM due to the different displacements.


And if the engine could rev to that RPM, it would scream! That's a big IF, though.
FieroWannaBe SEP 17, 08:36 AM

quote
Originally posted by Blacktree:

And if the engine could rev to that RPM, it would scream! That's a big IF, though.



And then, we would need a transmission with gear splits and final ratios that let us make that powerband useful.
gatorfrey SEP 17, 04:57 PM
I know inquiring minds wanted to know, so I checked with Darton.

The LS4 block can go to 4.000-4.155 bore with the wet sleeve install. Then with the combinations of crankshaft strokes factory and aftermarket, and a good valve train,there is much fun to be had.
However, the wet sleeve install runs $2500.00 alone. Still should be less than buying a LS3 block and adapter kit.
What is it they always say? Speed costs money.

But, it can be done.

[This message has been edited by gatorfrey (edited 09-17-2020).]

fieroguru SEP 17, 07:01 PM

quote
Originally posted by gatorfrey:
I know inquiring minds wanted to know, so I checked with Darton.

The LS4 block can go to 4.000-4.155 bore with the wet sleeve install. Then with the combinations of crankshaft strokes factory and aftermarket, and a good valve train,there is much fun to be had.
However, the wet sleeve install runs $2500.00 alone. Still should be less than buying a LS3 block and adapter kit.
What is it they always say? Speed costs money.

But, it can be done.



It has been done. There is a place in Ohio that makes LS4/F40 conversions for the Rossion. They sleeve all their blocks and do some additional custom machining on the engine and transmission to help them fit the engine bay that is narrower than the Fiero.
Will SEP 18, 09:00 AM

quote
Originally posted by gatorfrey:

I know inquiring minds wanted to know, so I checked with Darton.

The LS4 block can go to 4.000-4.155 bore with the wet sleeve install. Then with the combinations of crankshaft strokes factory and aftermarket, and a good valve train,there is much fun to be had.
However, the wet sleeve install runs $2500.00 alone. Still should be less than buying a LS3 block and adapter kit.
What is it they always say? Speed costs money.

But, it can be done.




People were sleeving LS1's to make 427's for quite while before the LS7 and Gen IV engines came out.
sourmash SEP 18, 07:15 PM

quote
Originally posted by gatorfrey:
However, the wet sleeve install runs $2500.00 alone. Still should be less than buying a LS3 block and adapter kit.
What is it they always say? Speed costs money.



Ouch. I paid $288 including core charge pulling my last used LS4 with all accessories and harness. But the Sun beat me to death doing it too.