4.9L Cadillac Information (Page 4/11)
Warlordsix AUG 13, 02:22 PM

quote
Originally posted by Spadesluck:

Warlordsix, what distributor is that? I see its an Accel but other than that not sure.



Stock HEI underneath.

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'87 Fiero 4.9 5-speed

Warlordsix AUG 13, 02:29 PM

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Originally posted by Reborn756:

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?




Most do the dual outlet for packaging reasons. 2.5" into the muffler and dual 2.25" out to the tips. Flow is not an issue. I think a true dual is possible (but likely tougher to route...I think getting adequate ground clearance beneath the driver's side, in particular, would be difficult). Nevertheless, I suspect some creative fabricators have made duals fit well enough.

Ernie

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'87 Fiero 4.9 5-speed

Reborn756 AUG 13, 03:38 PM
I'll probably stick with the single muffler then, I had ground clearance issues with my 86 Trans Am due to fitting duals as well, wouldn't want that on the Fiero. Shame, I like true duals for the "diagnose which bank isn't firing right" capabilities, but I'd rather play it safe. I'm a stickler for quality!

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- Darryl

Will AUG 13, 07:56 PM

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Originally posted by Reborn756:
The LS4 is over 100 pounds heavier than the 4.9L,




I don't think this is true of the long blocks. Engine weights are one of the hardest pieces of information out there on which to get apples-to-apples data. I've weighed a Northstar long block at 310 lbs.

But don't forget that when Gordon Murray was developing the McLaren F1, he put out RFPs to several manufacturers for the engine. BMW came back with "We missed your weight target by 20 kilos, but we brought 150 more HP than you asked for." I don't think there's anyone who would argue that a slightly lighter McLaren F1 with 150 fewer HP would have been nearly as famous as the F1 that McLaren actually built...

[This message has been edited by Will (edited 08-13-2020).]

sourmash AUG 13, 08:45 PM
Gordon is producing another greatest driver's V12 supercar now.
If the LS engine DID come in at 100 lbs more, it's worth the extra power it can produce; the upside would be worth it. But it's not likely it's that much heavier.

And your personalized rifle has plenty of value left in it. It's not true that it's worth nothing to anyone else.
Reborn756 AUG 13, 10:52 PM
It is a Shiloh Sharps, and if you know anything about the wait times, you also know there's people that would do anything to get their hands on one.

The LS also requires a lot more to properly fit and hook it up, plus (if I read right) it requires a smaller water pump and some other compromises with the cooling system. The 4.9L fits well enough that those compromises don't need to be made (once again, if I read right).

The car is an original yellow 88 Formula with sunroof. Given the low build numbers of these cars, I'd like to keep from totally butchering it, just doing enough to make it a more spirited driver!

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- Darryl

Will AUG 13, 11:57 PM
The LS4 is definitely a more involved swap than the 4.9, no doubt about that.

Keep in mind, the 4.9 is rated at 65 more HP than the 2.8, so it will definitely make the car more spirited. However, a 3900 V6 is an even easier swap and comes in 40 HP higher than the 4.9, although with ~50 ftlbs less torque. Technology has overtaken the aging platform. About 250 HP at the crank is about the highest I've ever heard of any built naturally aspirated 4.9 making.

If you're dead set on doing something as in-depth as building new heads for the 4.9, you probably should team up with John's 4.9 Performance mentioned earlier in the thread... I have no idea how big his customer base is, but he's quite fond of the engine. http://johns49performance.com/index.html

Also, Ed Parks of the Fiero Factory does (used to do?) in-house 4.9 swaps... not sure if he's interested in performance parts, though.
https://thefierofactory.com/

I've been thinking for a while that considering how light and cheap the 4.9 engines are, it's a shame it's so hard to get power out of them, as they'd make good claimer engines

[This message has been edited by Will (edited 08-13-2020).]

Warlordsix AUG 14, 07:39 AM
Here's some good info on the 4.9, including several pages of step-by-step rebuilding instructions from the June 1994 Automotive Rebuilder magazine....all of this is posted to the old Fiero Addiction website. One thing to note is the specs listed for HP and torque. Both peak early in the powerband where we spend 99% of our time on the street. Bottom line, a 4.9 Fiero is definitely quick and fun on the street. Especially fun with a manual.

http://web.archive.org/web/...on.com/caddy49b.html

Ernie

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'87 Fiero 4.9 5-speed

sourmash AUG 14, 08:11 AM
I figured you were talking about that sort of rifle or a Barrett .50 derivative.

My 4.5 is the slightly smaller version and is ok. It will keep up with today's traffic, particularly, it's quick off the line if you want. The previous owner had a 5 speed in it, and I believe two failed before he went with the auto. This auto trans performs "ok". And when cruising at interstate speeds it really will just keep increasing to where you're now driving too fast. But the gear ratio spacing isn't ideal. My 3.4 Chinese engine Equinox would probably outrun it.

My stock brakes are horrible and scary.
Mickey_Moose AUG 14, 01:45 PM

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Originally posted by 86FieroCentPa:

If money is no object and you want a V8, you'd be better off looking into an LS4 swap

Lots of detail here



I agree with this.


quote
Originally posted by Reborn756:
The LS also requires a lot more to properly fit and hook it up, plus (if I read right) it requires a smaller water pump and some other compromises with the cooling system. The 4.9L fits well enough that those compromises don't need to be made (once again, if I read right).




What you are proposing to do to the 4.9l you are not really requiring any less.

As one who has done the 4.9l swap (performance cam, ported heads, ported intake, etc) - you are far better off going with the LS4 swap. The time an money I spend on my car didn't really make it a performer. The 4.9l is a quick and easy swap to get more performance than the stock engine, but my car would choke itself past ~4300 rpm. Out of the gate it was quick, but it was not a distance runner. A 3800SC Fiero would spank it's ass.

If you want a quick and easy swap with some decent gains, then go for it. If you want performance, look someplace else.

I wouldn't waste money on new heads/etc for the 4.9l or trying to built it into something it is not.

[This message has been edited by Mickey_Moose (edited 08-14-2020).]