4.9L Cadillac Information (Page 3/11)
Johns 4.9 AUG 12, 01:09 PM
Looks great, dear1700! Nice fabrication work. Looking forward to see how well it works!
Cheers
86FieroCentPa AUG 12, 01:18 PM
If money is no object and you want a V8, you'd be better off looking into an LS4 swap

Lots of detail here
Reborn756 AUG 12, 02:55 PM
Brunelle: All fair points there. Given that the head would essentially be a copy of the OEM units I wouldn't expect any problems, but you're absolutely right: head gasket problems absolutely would be a concern, something I never factored in.

86Fiero: I've considered all three of the logical V8 options (Northstar, LS4, 4.9L). I'm not looking just for straight line performance. I want the car to handle well, and keeping it "trim" is going to be a big part of that. The LS4 is over 100 pounds heavier than the 4.9L, plus the transmission weight increase (if any). I'm of course open to any V8 options that meet my weight requirements. I'm specifically looking for a V8 so I have that V8 sound, which is why I'm not going the full 3800 cookie cutter route.

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- Darryl

pmbrunelle AUG 12, 11:30 PM
Well if you were just going to copy the OEM heads (same shape, but aluminium instead of cast iron), I don't think you would gain any power. Aluminium heads of the same shape would breathe just as poorly.

If anything, you would lose power due to sinking heat away from the combustion chamber into the coolant.

Seems like a bunch of headache for not necessarily much weight savings... OHV heads aren't generally so massive, though I haven't picked up 4.9 heads.

If you were going to go through the trouble of heads carved from billet, you might as well make them with different (i.e. sports car) ports, and intake manifolding to suit.

Intake and exhaust manifolds are likely to be manufacturable using more inexpensive cutting and welding of tubes to make weldments.
Dennis LaGrua AUG 13, 06:15 AM

quote
Originally posted by dear1700:


Nope, about two weeks of working on it on the side. I’m sorry if using a drill, grinder and welder are outside your level of expertise.

Here is the required adapter plate



While I envy your fabrication skills, trying to transform a low revving high torque engine into something it is not may not produce the results that you are seeking and if you achieve the power goal will reliability go along with it? The head sealing capability on the 4.9L is not great. That's why GM recommended adding sealer to the coolant even when new. If you evaluate the cost vs potential large power gain vs reliability, I do not believe that a satisfactory result can be achieved.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Warlordsix AUG 13, 09:21 AM
"I imagine the engine compartment is awfully cramped as it is with just an NA 4.9L crammed in there!"

Negative. Plenty of room in the engine bay around the 4.9. Frankly, there's much more room around the 4.9 in a Fiero than there is around a 4.9 in a DeVille. Just relocate the battery up front like most folks do anyway for other good reasons.

This is not the best shot, but I can easily change all my plugs, replace the belt, alternator, water pump, AC compressor, starter, etc., without disassembling anything else first.

Ernie

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'87 Fiero 4.9 5-speed

Reborn756 AUG 13, 09:27 AM
Warlord: That does fit VERY well in there. Man, almost looks like the car was built with that engine in mind, it looks that clean in there. Who knows, maybe if the Fiero would have lasted longer, the end result would have been one with a modified 4.9L, designed to better suit the application?

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- Darryl

Warlordsix AUG 13, 09:50 AM

quote
Originally posted by Reborn756:

Warlord: That does fit VERY well in there. Man, almost looks like the car was built with that engine in mind, it looks that clean in there. Who knows, maybe if the Fiero would have lasted longer, the end result would have been one with a modified 4.9L, designed to better suit the application?




Zactly, Until I tell them, 99% of people who ask about this car have no idea that engine was swapped in. Even the exhaust fits perfectly in the stock location. Here's a photo of the muffler I'm using....deep, powerful rumble without the raspy sound you hear too often these days from guys who just make their Mustangs louder. My neighbors say my Fiero sounds like my other neighbor's Viper, and I have to agree. (BTW Can anyone tell me why photos just seem to post wherever the hell they want to post, before, after, in the middle of text?)

Ernie

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'87 Fiero 4.9 5-speed

Spadesluck AUG 13, 01:08 PM
Warlordsix, what distributor is that? I see its an Accel but other than that not sure.
Reborn756 AUG 13, 02:01 PM
Warlord: That looks awesome. I'm a big fan of the Cherry Bomb Extreme welded mufflers myself. Think a set of custom headers and true duals would be possible, or is sticking with the dual out muffler a better idea?

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- Darryl