Guest Will Posted December 29, 2001 Share Posted December 29, 2001 Engine #1 Shortblock detailed here: http://www.airflowresearch.com/Articles/A3-P1.htm topped off with Vortec cylinder heads with LT4 intake modified for Vortec bolt pattern and distributor. Engine #2 LT1 block, with L99 (4.3L Caprice engine) crank and rods (3.00 stroke, 5.940" rod), and Keith Black 11:1 350 pistons. The smaller displacement drops the compression ratio to 9.5:1. The resulting engine has 302 cid and a 1.98 (!) rod/stroke ratio. Top that short block off with LT4 heads & intake, with a suitably agressive cam, and run it to 7K. This configuration (4.00 bore x 3.00 stroke) is the little known Chevy 302 built for under 5.0 litre Trans Am racing in the late 60's. The modern version is better, though, with a larger R/S ratio. Question: The L99 was and LT1 style engine. When they shortened the stroke, they lengthened the rods, rather than increasing the pistons' comrpession height. Did GM do the same thing with the 4.8L iron block version of the LS1? Engine #3: If so, then 4.8L crank and rods could be used in an iron 6.0L truck block and topped with LS6 heads and intake for the return of the 327! Ha! An alternative configuration would be to use 4.8L crank and rods in Aluminum 5.7L block for 311 cid. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 29, 2001 Share Posted December 29, 2001 I am interested in everyone's thoughts on the latter two engines - the first engine is a dandy. I like the idea of a short stroke to limit low end torque. Quote Link to comment Share on other sites More sharing options...
JoeinCA Posted December 29, 2001 Share Posted December 29, 2001 any ideas about the first engine in that list? i read the article, and was pretty impressed. what kind of numbers do you guys think that would put out with the same heads, but with the bigger valves? maybe i could do this sort of an engine for my Z... Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted January 4, 2002 Share Posted January 4, 2002 The first engine is very interesting, with power and torque rivalling the LS6(possibly driveability and fuel consumption too), it's an excellent engine. Though the engine wouldn't have had accessories on it for the dyno, so the LS6 is probably better. But, a few thoughts: With such a high compression ratio, would it be possible to put a decent cam in there, to take advantage of the high-revs that big-bore invites?..... I think part of the reason they were so happy to use restrictive valves, heads, manifolds, is because they limit how much air you get into the engine. Sounds like a "duh" conclusion, but, if you don't have as much air in the engine, it won't detonate even with a high compression ratio. If I'm wrong however, and it can use less restrictive intake and a rougher cam, then it sounds like a winner. Any thoughts on this? Anyone had experience with this kind of engine? P.S. I remember reading that while small R/S increases the wear on the cylinder bores(and alters the motion of the piston). Large R/S has disadvantages too but I can't remember what. Does anyone know? Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted January 4, 2002 Share Posted January 4, 2002 heres some engine ideas, heres a random asortment from my library http://www.ryanscarpage.50megs.com/ http://mysite.directlink.net/ldodd/EngineBuild.htm http://www.findarticles.com/cf_0/m0BUW/2_41/68322476/p1/article.jhtml?term=cadillac+engine+swap http://www.off-road.com/chevy/tech/454engine/ http://members.home.net/ctandc/350.htm http://www.skunk.net/boatengines-496.htm http://www.carcraft.com/editorial/article.jsp?id=868 Quote Link to comment Share on other sites More sharing options...
Guest Will Posted January 13, 2002 Share Posted January 13, 2002 Those all seem to be engines with reasonably convetional geometry. The three engines I mentioned all use long rod geometries. I just read that Agonstino Racing Engines can resleeve LS1's to accept up to 4.125" bore. With the 83 mm stroke from the 4.8L engine, that works out to just larger than the regular LS1, with bigger bore, shorter stroke, and longer rods. Hello?!? GM?? Quote Link to comment Share on other sites More sharing options...
Guest super280z Posted January 14, 2002 Share Posted January 14, 2002 Will, MTI out of Houston has been doing a 422 solid roller motor on an 6.0 iron block for quite some time now. talk about a total beast. about the above mentioned motor combo's, most heads/cam LT1 engines easily spin up to 7k (stock bottom end). it all has to do with how much money you feel like putting into the valvetrain, and pain in the butt time you spend tuning something that wind's that high. FYI, take a peak at rod/main bearing sizes for the LT1 / 4.3 caprice. a few of these combo's might not be as easy as you'd think. i dont mean to rain on your parade but i do want to look at these setup's practically. i really like the tech article, it's a good read. some interesting info about the tq #'s with the 1:9 rod stroke ratio. however im pretty sure that the AFR's in the article will flow better and be a better overall head than a set of vortec's. the 352's are definately a good combo if you're into odd setups. any other thoughts guys? Quote Link to comment Share on other sites More sharing options...
Guest Will Posted January 14, 2002 Share Posted January 14, 2002 I'm almost certain that the L99 and LT1 have the same sized mains. Rod sizes aren't necessary to compare as the L99 crank and rods would be used together. I don't know about that.. The Vortec heads are insanely good... and cheap. They're also a tall port design with an inherently smaller short turn radius than a small block head with conventional ports. Even if the AFR's make more power at the very top, I don't think it would be by much, and I believe the Vortec's would make more in the lower RPM because of higher port velocity. I know there's no replacement for displacement, but everybody does strokers. I just like these engines, mostly because they're heavily oversquare and have long rods. I've been curious for a while about how a stroker like the 422 would do against a long rod 328 or 347 if both had the same compression ratio and were turbocharged. That would make things interesting. Would the long rod engine be able to run enough more boost to equal the long stroke engine in horsepower? It would only have to run 20% more boost to make up for the difference in displacement, but the smaller engine might be able to extend flow stall to a higher RPM and have a wider power band than the larger engine... Quote Link to comment Share on other sites More sharing options...
Guest Will Posted January 15, 2002 Share Posted January 15, 2002 Does anyone know what the stroke is on the MTI or Lingenfelter strokers? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted January 16, 2002 Share Posted January 16, 2002 I'm pretty sure that as long as you sized the turbo's (twins ) accordingly to the flow of the engine then yeah I think it'd be a pretty even race, although as you mention you'll need to be shifting sooner with the stroker as its RPM's will IMHO be decreased, meaning a smaller powerband. *shrug* Use a powerglide and it wouldn't matter at least in the quarter unless you ran out of RPM from low gearing... (A bit buzzy for extended freeway driving though) Sorry got carried away with the cyber-race Regards, Lone Quote Link to comment Share on other sites More sharing options...
Guest Will Posted February 8, 2002 Share Posted February 8, 2002 OK, I just heard back from GM Goodwrench. The 4.8 engine uses an 83 mm stroke and 159.65 mm conrods: R/S ratio 1.92 THe 5.3, 5.7, and 6.0 engines use a 92 mm stroke and 115.15 conrods: R/S ratio 1.68 Any LS1 style engine built around the 4.8 litre crank and rods will have quite favorable 1.92 rod/stroke ratio. Quote Link to comment Share on other sites More sharing options...
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