Guest Muscle Z Posted February 4, 2003 Share Posted February 4, 2003 before anyone mentions to me that I should check out the other related thread, I have read most of it already. Anyway, heres the scenario... I recently took posession of a friends 1980 Datsun 280ZX 2+2. I plan on doing the Z/V8 conversion that seems to be ever-so-popular. However, I am really not sure which motor to go with. I either want to go with Chevy's LT1 (350) or Ford's 2001 Cobra Motor (4.6L DOHC 4V). Can anyone give me the pro's & con's of both swap? Maybe possibly share some stories on experiences doing either swap?? Or maybe I should pick the 302? Thanks to all that help. -Shawn Quote Link to comment Share on other sites More sharing options...
jeromio Posted February 5, 2003 Share Posted February 5, 2003 If you do any research on that expensive 4.6 (and outrageously $$$ 32V) you'll also find that they are very delicate and costly to repair. Quote Link to comment Share on other sites More sharing options...
Guest AlsoRanFPrepared Posted February 5, 2003 Share Posted February 5, 2003 Ditto. The 4.6 DOHC can be a good motor but it is huge. It is bigger than a Ford 460 in every dimension except length as the water pump on the 460 makes it stick out further. The LS1 will give you a smaller size, larger displacement and has a less delicate valvetrain. Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted February 5, 2003 Share Posted February 5, 2003 I'd go with the LT1. Or LS1. Or LS6! Basically, the DOHC 4.6 gives up as much in displacement as it gains in revs (4.6 liters at 7500rpm roughly equivalent to 5.7 liters at 6000rpm). But it has way less low-end torque and it is VERY bulky, which is why the Cobras had to have another bulge on top of the already-very-high Mustang hood. Also, the OHC and DOHC Ford motors weigh enough that the Mustang went from 3200lb with the 302 to 3300 lb with the SOHC GT motor and 3400 lb. with the DOHC Cobra motor. It's gotta be heavier than a small-block Ford, or a small-block Chev. Just about all the increased weight in the OHC and DOHC motors is up high, as well. If it was me, I'd rather have an OHV small-block (Chevy or Ford) in my Z than the 4.6 DOHC motor. Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted February 5, 2003 Share Posted February 5, 2003 Another ditto on the fragility of these motors. Two of them expired last year at time trials events. My L6 has been doing these kinds of events (47 track days) since 1995, no problems! One of the victims felt the very-tight the bearing clearances were to blame. Both instances were bottom-end failures, BTW. How could Ford have built a motor so big and heavy, with so little (relatively) displacement, and still have reliability problems? GM (not that I'm a fan) had the right idea. Of course they still lost the war! Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted February 6, 2003 Share Posted February 6, 2003 Bigger than a 460V8? The Mod-Motor 4.6L is wider than either the infamous Boss 429 or the equally wicked SOHC 427! Why Ford didn't simply resurrect the 255ci 4-cam Indy motor instead of creating this monstrousity is beyond me. My apologies to any Mod-Motor fans among us; I just don't care much for it at all. Quote Link to comment Share on other sites More sharing options...
Guest John Adkins Posted February 6, 2003 Share Posted February 6, 2003 Originally posted by Quantrex:Bigger than a 460V8? The Mod-Motor 4.6L is wider than either the infamous Boss 429 or the equally wicked SOHC 427! Why Ford didn't simply resurrect the 255ci 4-cam Indy motor instead of creating this monstrousity is beyond me. My apologies to any Mod-Motor fans among us; I just don't care much for it at all. I read the modular v8 was originally designed to be used in transverse front wheel drive cars. The width from valve cover to valve cover wasn't a concern originally due to this, but it's short in the bellhousing to waterpump dimension for fitting between the front wheels. Quote Link to comment Share on other sites More sharing options...
Guest MarksM Posted May 13, 2003 Share Posted May 13, 2003 There's no doubt the mod motors have a weak bottom-end from the factory. Put some good forgings in there, however, and they can make some wicked power. Look at the 2003 Cobra. Plently of those are well into the 500+ RWHP range with just bolt-on's. It's width makes it impractical for most engine swaps though. Quote Link to comment Share on other sites More sharing options...
Mudge Posted May 29, 2003 Share Posted May 29, 2003 There is a guy on Corner-Carvers.com on his 5th DOHC 4.6L engine. I lost one at STARTUP in 1998, never heard back from Ford as to why, it was a 97 Cobra. Quote Link to comment Share on other sites More sharing options...
alsil Posted May 29, 2003 Share Posted May 29, 2003 Man, I'll stick with my '95 5.0 motor!!!! DAMN! Had no idea they were so fragile. DAMN!!! Quote Link to comment Share on other sites More sharing options...
JoshB 240Z Posted May 29, 2003 Share Posted May 29, 2003 Just picked up my '01 GT after having the engine replaced for a rod knock. Ford replaced the engine under warranty but not without argument from the dealer. They claim that the engines have such tight tolerances that the slightest oil "problem" can cause abnormal bearing wear. So the dealer started accusing me of not changing the oil properly or on schedule. Luckily the dealer had done most of the oil changes so it wasn't a hard fight to win. This car has always had it's oil changed at the scheduled mileage and is only used as a commuter and road trip car. We noticed the problem when we would start the engine and it would rattle as if it didn't have any oil. The problem became worse so we took it to the dealer and they had the engine replaced. Whatever the cause the problem definitely needs attention. For performance applications I will stick with the 302. I have 3 of them sitting on engine stands in my garage waiting for their opportunity. Josh Quote Link to comment Share on other sites More sharing options...
Moridin Posted July 2, 2003 Share Posted July 2, 2003 I've heard a few of the engines let go from oil starvation problems. I'm sure its nothing more than on Accusump oil accumulator couldn't take care of. Plus, you can oil your motor before you start it for a lot less wear. Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted July 3, 2003 Share Posted July 3, 2003 Friend's shop hops up 4.6mod motors all day long - he doesn't see that many failures. Most of them expire from being run lean, detonation, or in some cases from too much power - I've seen rods removed from blower cars bent like an S. Hypereutectic pistons don't help either! The 03 Cobra runs Manley rods and aftermarket forged pistons. 500+RWHP is the reuslt and one of them has already run a single digit 1/4 on the stock bottom end - aftermarket blower. So which would I do? If you were looking at an 03 Cobra assembly the answer would be EASY However between a 1997 assembly and an LT1 which is MUCH easier to bolt in I'd do the LT1. It won't rev as high and the Optispark sux but of those two it would be easier to work with. The 4.6 WILL fit I believe, I've posted measurements before, but the SBC has been done and documented. Quote Link to comment Share on other sites More sharing options...
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