Lately, I've been reading the three threads on supercharging the Cadillac 4.9 with an M90 supercharger. A question has popped into my head, and I thought I'd ask it here to start a discussion.
Say you have two identical, bone stock Fieros: -One of them gets a bone stock LS4, -the other gets a 4.9 with an Eaton M90 Gen V supercharger, and no other modifications other than the ignition system and engine management modifications necessary to make everything work properly together, and maybe something to lower the compression ratio to make it work optimally.
Which one of the two do you think would be the most fun to drive, and why?
Correct me if I'm wrong, but nobody who has made a 4900SC has dyno tested it yet. That is why this question is not about numbers, but about driving enjoyment.
------------------ Silver 88 coupe, Duke with TH125C (for now) White 88 GT, 3800 L67 with 4T65E-HD (sold)
[This message has been edited by Hidalgo (edited 01-27-2016).]
Do we have to guess how much torque the 4.9 will produce in order to answer your question? It should weigh 150 llbs less than a LS4, and I would like that.
Originally posted by Gall757: It should weigh 150 llbs less than a LS4, and I would like that.
I am not convinced the 4.9 SC would be lighter. Cast iron cylinder heads...and have you weighed the M90 lately? Not to mention all the work it would take to make the M90 work on the 4.9. I think the LS4 would end up weighing a bit less.
The 4.9 is a low revving engine. It has high torque and low HP. It doesn't really belong in a lightweight (compared to the cars the 4.9 came in) sports car.
Do we even need to bring up the potential? We are comparing a stock LS motor to a 4.9 that is already pushed about as far as it will go.
Yeah, not even a discussion. The weight savings alone has my attention.
You're completely right. I forgot that the 4.9's cast iron heads, along with the added weight from the M90 supercharger, would make it heavier than an all-aluminium LS4, negatively affecting the Fiero's handling.
What about in a straight line? Or when passing someone on a highway?
[This message has been edited by Hidalgo (edited 01-27-2016).]
Data from another thread has the LS4 at 478 Lbs. and the 4.9 at 360 Lbs. Forgot about the supercharger, so maybe they weigh about the same when all in the car.
Data from another thread has the LS4 at 478 Lbs. and the 4.9 at 360 Lbs. Forgot about the supercharger, so maybe they weigh about the same when all in the car.
Wow, now that sure is a surprise. I wouldn't have thought that the weight difference would be so big, and I would have thought the LS4's all-aluminium construction would make it lighter than the 4.9 L26, even though the LS4 is larger.
You know, that list contains some surprising numbers. If you subtract the weight of an 3800NA from the weight of a 3800SC to have a ballpark figure for the weight of the supercharger, and then add that supercharger weight to the weight of an L26 Cadillac 4.9, you come to the conclusion that a 4900SC would weigh less than a 3800SC, an LS4, and a Northstar. Maybe the 3 forum members that made 4900SCs were on to something?
I'm sure that, given a decent budget, a seasoned hot rodder could make a 4900SC reach 300hp. Granted, it would take a lot of time and money, as you would need things like a custom-ground cam, an intercooler, methanol injection, etc. But wouldn't the weight savings make it worthwhile?
[This message has been edited by Hidalgo (edited 01-27-2016).]
I would go for the LS4 without hesitation. Here's why:
1) The LS series V8 is leaps and bounds more reliable than a 4.9 with a supercharger strapped on top.
2) The LS series V8 has more aftermarket support, which means more goodies to upgrade it with.
3) The LS series V8 has greater performance potential.
The reason why the 4.9 is so lightweight is because it's flimsy. The LS series V8 was designed from the factory to be a beefy engine that can handle a lot of punishment. You can easily get 500+ HP out of an LS series V8, using readily available aftermarket stuff. But with the supercharger on that 4.9, you're basically pushing the limits of its power potential, and its reliability. And if you're lucky, you might be making as much power as a stock LS4.
[This message has been edited by Blacktree (edited 01-27-2016).]
Data from another thread has the LS4 at 478 Lbs. and the 4.9 at 360 Lbs. Forgot about the supercharger, so maybe they weigh about the same when all in the car.
A fully dressed stock LS4 is nearing 500 lbs, but that's with cast iron exhaust manifolds, crossover tube, big cast iron alternator bracket, AC compressor, and power steering pump.
I don't know what 4.9 was weight at 360 lbs, but it must not have had anything on it at all.
Has anybody actually weighed the 4.9l, or are we basing its weight off what someone said on some forum somewhere? The 360lb "we" work with seems really light. Consider than an all-aluminum Duratec or Ecotec weighs 300lbs. A book of Cadillac history I have quotes the HT4100 at 420lbs (and, Hemmings agrees - http://www.hemmings.com/mag...T4100/3722021.html). What caused the 4.9l to lose 60lbs? The guys over at Locost suggest the 4.9l weighs 340lbs without accessories (flywheel, starter, alt, PS, exhaust), which I might buy into. Is the 480lb LS4 weight quoted with similar considerations? The 300lb Ecotec/Duratec weight is *with* those things, and I suspect the LS4 is as well. I think similarly equipped, the weight difference is only about 60lbs. This is all just what I think - the only weight I actually know is a ready-to-run Ford Duratec, which means nothing here.
A book of Cadillac history I have quotes the HT4100 at 420lbs (and, Hemmings agrees - http://www.hemmings.com/mag...T4100/3722021.html). What caused the 4.9l to lose 60lbs? The guys over at Locost suggest the 4.9l weighs 340lbs without accessories (flywheel, starter, alt, PS, exhaust), which I might buy into. Is the 480lb LS4 weight quoted with similar considerations?
If I recalculate my 4.9 + M90 weight using 420 lbs instead of 360 lbs, I still end up with a total that is 2 lbs lighter than the 478 lbs weight of the LS4, so I'm not sure if both numbers are comparable. Shouldn't the 4900SC be heavier than the LS4 when both engines are comparably dressed?
[This message has been edited by Hidalgo (edited 01-27-2016).]
Originally posted by Hidalgo: If I recalculate my 4.9 + M90 weight using 420 lbs instead of 360 lbs, I still end up with a total that is 2 lbs lighter than the 478 lbs weight of the LS4, so I'm not sure if both numbers are comparable. Shouldn't the 4900SC be heavier than the LS4 when both engines are comparably dressed?
You can't just count the weight of the blower by itself. It's not a bolt-on kit. You'll have to engineer an adapter, or mount it on the side of the engine somehow, with an adapter and piping to route up to the intake, or a custom intake manifold. An adapter on top raises the height of the engine, and requires cutting the decklid. You'll also probably have to drive the blower from the serpentine drive, which creates other problems as well.
If it's easy enough to get an LS4 where you are, it's going to be the better option, hands down, even if the stock 4.9 was 60-100 lbs lighter than the stock LS4.
LS4s are much rarer and pricier up here. I already have a 4.9. I bought a very low mileage 91 DeVille as a winter beater for now, and a potential donor for the future. The 4900SC discussion was just me living vicariously through those of you who have the time, money, space, tools, and know-how to follow through on such elaborate projects. Therefore, if my 88 coupe gets a 4.9, it'll be a bone stock one, with the stock 4T60E. But after reading those 3 threads and having this discussion with you guys, I must admit, if my Fiero does get a 4.9 swap, I'll make sure I mount it as low on the cradle as possible. You know, just in case I need some extra clearance on top in the future...
------------------ Silver 88 coupe, Duke with TH125C (for now) White 88 GT, 3800 L67 with 4T65E-HD (sold) White 91 Cadillac DeVille (winter beater and possible swap donor)
LS4s are much rarer and pricier up here. I already have a 4.9. I bought a very low mileage 91 DeVille as a winter beater for now, and a potential donor for the future. The 4900SC discussion was just me living vicariously through those of you who have the time, money, space, tools, and know-how to follow through on such elaborate projects. Therefore, if my 88 coupe gets a 4.9, it'll be a bone stock one, with the stock 4T60E. But after reading those 3 threads and having this discussion with you guys, I must admit, if my Fiero does get a 4.9 swap, I'll make sure I mount it as low on the cradle as possible. You know, just in case I need some extra clearance on top in the future...
Well, since you're going with the 4.9 anyway, if you really want to go forced induction on it, a turbo would fit much better. You can mount it right behind the driver side, above the transmission, on a y-pipe, with the air flowing straight through from the stock air intake area inside the body, through the turbo and right out to the throttle body. You can stay under 10 PSI without an intercooler, or retune for more boost with higher octane fuel, and add on some water/meth injection if you want. With 7-8 PSI boost, you should be able to hit around 300 HP, and that's where a supercharger would put you.
Tho I haven't had one in a Fiero before. I can tell you ease of ownership was a pain. Parts were hard to find, and when I found them, they cost quiet a bit.
That is the biggest issue with the 4.9, the after market support is very small. The LS4 has parts for days. HOWEVER, the 4.9 I had, had over 194,000 by the time I sold it. And the thing STILL ran like a champ. If reliability is what you are looking for, the 4.9 is a great choice. Not sure how well the SC will change the reliability tho.
But, let me try to stay on track here.
LS4 vs. 4.9SC....
Drum roll please....
LS4, with EASE. The 4.9 might have 275LBS of torque (that is 5 more than a L67) but has a mere 200HP. As mentioned above, the LS4 comes with over 300HP with plenty to work with. Even a SC on top of that 4.9, you might have more torque (maybe) but considering the weight savings, and the HP, that LS4 will eat it up.
------------------ Every fiero has a story, It's our job to keep that story alive.
[This message has been edited by zzzhuh (edited 01-27-2016).]
Originally posted by Hidalgo: If I recalculate my 4.9 + M90 weight using 420 lbs instead of 360 lbs, I still end up with a total that is 2 lbs lighter than the 478 lbs weight of the LS4, so I'm not sure if both numbers are comparable. Shouldn't the 4900SC be heavier than the LS4 when both engines are comparably dressed?
Unfortunately neither my book nor Hemmings indicates whether the 420lb figure for the HT4100 carries over to the 4.5l or 4.9l so we still don't know exactly what that includes. However, it *seems* that at least HT4100@420lbs and LS4@480lbs are both GM figures and would be similarly equipped. I could buy into that. I definitely can't comment on whether all the HT motors weigh the same, but I'd bet each iteration is heavier than the last by at least a few pounds. More crank, more rods, etc. adds at least some weight. The 4.9l vs. LS4 gap could be narrower than the 4.1l vs. LS4.
Still, I'd be totally willing to give the weight edge to the 4.9, even to the tune of 60lbs. GM did everything they could to make the HT motors light, up to and including the super-weird head configuration that results in a major flow & power restriction. The LS4 is a totally modern motor, based on parts designed to deliver huge horsepower while still remaining quiet and durable. I could definitely see GM adding material to the block for rigidity and noise dampening that the HT doesn't have, and the LS4 heads are quite a bit bulkier than the HT heads. Add in some weight for VVT and DoD tricks, probably less aggressively crappy exhaust... I see how you could get a 60lb advantage in the 4.9l.
But, whatever, it's all speculation and we'll probably never know the answer.
IMHO, like every Fiero engine swap there is ideal (which might be an LS4 with cam/intake/exhaust costing a few grand and mountains of time) and a pragmatic (which might be a 4.9l which doesn't cost much money or time, until you add the blower ). I think they are two different discussions. Like the Camaro and the Cruze, they each have their application.
*Personally* the only question I would ask is high-value V6 or LS4... Because the high value is easily a match for the 4.9l in terms of performance, difficulty, and cost *and* is a totally modern motor easy to find at any scrapyard anywhere. I guess the only "unless" would be if you want a V8 rumble, because the V6 just ain't gonna deliver that.
Originally posted by thesameguy: Still, I'd be totally willing to give the weight edge to the 4.9, even to the tune of 60lbs. GM did everything they could to make the HT motors light, up to and including the super-weird head configuration that results in a major flow & power restriction. The LS4 is a totally modern motor, based on parts designed to deliver huge horsepower while still remaining quiet and durable. I could definitely see GM adding material to the block for rigidity and noise dampening that the HT doesn't have, and the LS4 heads are quite a bit bulkier than the HT heads. Add in some weight for VVT and DoD tricks, probably less aggressively crappy exhaust... I see how you could get a 60lb advantage in the 4.9l.
The LS4 does not have VVT (and really, the phaser doesn't weigh that much anyway).
In another thread, I was asked what the LS1/6 and LS4 weigh. The GM #s for the LS1/6 are 479 lbs for auto, and 497 lbs for manual (flywheel and clutch is heaver than the flexplate, and the tq converter isn't included in engine weight there). The LS4 weighs the same as the auto LS6, in stock trim fully dressed. The stock 2.8 I think is around 380 lbs.
However, even if the fully dressed 4.9L does only weigh 420 lbs, the weigh savings is not enough to balance out the performance difference. The LS4 will still win there. If the weight difference is a worry in terms of handling, then it'd be better to go with a little more spring in the rear than go with the 4.9 over an LS4.
If the weight difference is a worry in terms of handling, then it'd be better to go with a little more spring in the rear than go with the 4.9 over an LS4.
There are stiffer springs for the rear 88 suspension? All I have ever seen are lowering springs, which I don't want. I have never seen stiffer rear 88 springs. Do you know who makes them?
------------------ Silver 88 coupe, Duke with TH125C (for now) White 88 GT, 3800 L67 with 4T65E-HD (sold) White 91 Cadillac DeVille (winter beater and possible swap donor)
The 4.9L Cadillac has its place for an engine swap, it is easy to do and one of the most inexpensive engine swaps that provides 275 ft lbs of torque and 200 HP. If performance is the no 1 priority there are better choices, the LS4 being one of them. As pointed out the 4.9L Cadillac was designed for a 4000 lb car, to provide good acceleration, highway gas mileage and smooth operation. It makes a great highway cruiser, and succeeds at meeting these requirements with a redline below 5,000 RPM. Several years back forum member PBJ turbocharged this engine in his Fiero and ran 12 second 1/4 mile times; very good but really not what this engine was designed for. I would have concerns with long term reliability of a boosted 4.9L driven this hard. The LS4 is a far more difficult swap but it provides more horsepower and room for modifications.
------------------ " 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, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, 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 "
There are stiffer springs for the rear 88 suspension? All I have ever seen are lowering springs, which I don't want. I have never seen stiffer rear 88 springs. Do you know who makes them?
Converting to coil-overs will open up a whole world of options. For stock spring replacements, it might require getting them custom made.
Would going from a Duke and TH125C to a stock 4.9 and 4T60E require stronger springs or coilovers in the back?
Doesn't "require" them, but with the extra weight you might notice the rear sit slightly lower, or you might feel the handling a bit different if you like to take corners tight (which I guess you're probably not doing much of with the duke anyway).
Other LSx engines have different pros/cons. I wouldn't say that any one of them is "the best" to choose. It depends on what your goals are with a build. LS is a great engine, but it's not for everyone, and the other LSes are much more expensive to do, and require a lot more fabrication and welding to get in.
There is no better or best... just personal preference given your budget, skills, desired results vs. work, etc...
I did a couple 4.9's 10+ years ago and have a LS4/F40 Fiero.
The 4.9 is light, cheap, fairly simple to install, and delivers good bang for the buck in stock form. It is a huge improvement in the driving experience vs. stock fiero engines and delivers lots of smiles per mile. But it has its limits... Going beyond stock is more challenging & expensive with one of the larger limitations is properly tuning the new combo. Over the years there have been at least 1 turbo, 1 max effort N/A build, and 1 supercharger build that made it to running/driving stages. Results when they were posted (1/4 mile, dyno, etc) were nothing stellar and for the last 2 (max effort and supercharger) it was likely the tune that was holding them back.
If you can do the needed fabrication to install a supercharger on the 4.9, you can do the needed work to install an LS4/4T65, but there is about 3 times the wiring. However with the LS4 you get 303 hp stock (might gain a few with the Fiero install), nearly unlimited aftermarket support for performance parts (whatever HP you start with is never enough) and the supporting ability to properly tune the combination.
I wouldn't get terribly hung up on weight between the two... lots of decisions you make during the build will help or hurt the final weight potential of the swapped vehicle. My 88 Formula with LS4/F40 weighs in at 2807 lbs...
The LS4 is the best LS for a Fiero swap because it's the only LS that was designed to be mounted transversely. Am I right, or are there other reasons to choose it over the other LS engines?
------------------ Silver 88 coupe, Duke with TH125C (for now) White 88 GT, 3800 L67 with 4T65E-HD (sold) White 91 Cadillac DeVille (winter beater and possible swap donor)
However with the LS4 you get 303 hp stock (might gain a few with the Fiero install), nearly unlimited aftermarket support for performance parts (whatever HP you start with is never enough) and the supporting ability to properly tune the combination.
You're not the first person in this thread to mention the "nearly unlimited aftermarket support for performance parts" that the LS engines enjoy, but aren't most of those parts designed for the longitudinally mounted LS engines, and not for the LS4? Of course, even if I'm correct about this, I know that the LS4, even though it may enjoy less aftermarket support than the longitudinally mounted LS engines, still has a lot more of it than the 4.9 L26. Even Cadillac specialists like CHRFAB don't have a single 4.9 product advertised on their websites.
------------------ Silver 88 coupe, Duke with TH125C (for now) White 88 GT, 3800 L67 with 4T65E-HD (sold) White 91 Cadillac DeVille (winter beater and possible swap donor)
Originally posted by Hidalgo: You're not the first person in this thread to mention the "nearly unlimited aftermarket support for performance parts" that the LS engines enjoy, but aren't most of those parts designed for the longitudinally mounted LS engines, and not for the LS4? Of course, even if I'm correct about this, I know that the LS4, even though it may enjoy less aftermarket support than the longitudinally mounted LS engines, still has a lot more of it than the 4.9 L26. Even Cadillac specialists like CHRFAB don't have a single 4.9 product advertised on their websites.
Almost any part designed for the standard Gen IV engines will work fine in the LS4, either as-is, or with little modification.
The two main things that can't be used on the LS4, are oil squirters (I discovered this the hard way), and larger cylinder heads (though, these can be used if you re-sleeve and use a large bore, but big $$$ for that).
Originally posted by Hidalgo: You're not the first person in this thread to mention the "nearly unlimited aftermarket support for performance parts" that the LS engines enjoy,
That is because its true!
Just look at my LS4 build: LS7 MAF, LS2 90mm TB, LS2 Intake Manifold, LS2 Injectors, DoD Camshaft designed for a 6.0L G8 (RWD), LS7 factory exhaust manifolds. LS4 is factory rated at 303 hp, but has the same heads as used on 400 hp LS2 and LS6. By using better factory parts to replace the restrictive stock LS4 ones (MAF, Intake & Exhaust) and installing an aftermarket camshaft for a 6.0L RWD engine (with matching push rods and valve springs) I went from 303 fwhp to about 420-430 fwhp (382 rwhp) and still get 29 mpg on the interstate.
LS1, LS2, L6, Fast 102, and other aftermarket intakes have been used on LS4's. 5+ vendors will CNC port the heads, or 5+ other vendors offer aftermarket versions. Hundreds of camshafts available - you can even get one custom spec'd for your application based on parts used and intended purpose. Any LS exhaust manifold (or aftermarket header) will bolt to the LS4, but not all will clear the 4T65e-hd or fit in a Fiero, but there are LS4 headers for the W-body that with some work - they have been used in an LS4 Fiero. There are also turbo kits for the LS4 in the W-body and with modification in a Fiero (at least 2 turbo LS4 Fieros have been built)
With the square (LS3/9) to cathedral (LS1, 2, 4, 6, etc) port adapter, people have been working on kits to install the LS9 (or aftermarket equivalent) superchargers onto 5.3s. One was even done on an LS4 in a W-body... but that took some pretty significant custom work.
There are also turbo kits for the LS4 in the W-body and with modification in a Fiero (at least 2 turbo LS4 Fieros have been built)
I don't know which 2 you're thinking about, but here in Montréal a member of the local Fiero club owns a Lamborghini Murciélago clone built on a stretched 88 Fiero frame, and powered by a turbocharged LS4. This is the turbo kit he used :
Well, if we're going to list parts on an LS4 build, maybe I should list what I've got going in my LS4:
After market: Wiseco pistons Lunati rods w/ARP bolts Callies Magnum crank (custom short stroke, and machined to shorten the flange) Xceldyne/Del West Ti valves Harland Sharp roller rockers Isky lifters Isky valve springs Custom ground CamMotion VVT camshaft Comp Cams VVT limiter kit IWIS c5r/c6r timing chain FIC injectors ARP main and head studs Improved Racing crank scraper and oil pan baffle Improved Racing oil cooler adapter
OEM retrofit: L92/LY6 VVT phaser, cam bolt, and timing cover LS2 intake manifold and throttle body LS7 MAF LS2/3 Corvette oil pan LS2/3 oil pump
And those are just the parts I can recall at the moment, and which are limited to the engine itself.
Originally posted by Hidalgo: I don't know which 2 you're thinking about, but here in Montréal a member of the local Fiero club owns a Lamborghini Murciélago clone built on a stretched 88 Fiero frame, and powered by a turbocharged LS4. This is the turbo kit he used :
As you can see, it was designed for W-bodies with LS4s. He got his LS4 swap parts from Fieroking.
Say, Fieroguru, the build you described, which one of your LS4 swaps is it? The one with the stock automatic, or the one with the F40?
The orange Murci that dratts had? Or another Murci with the same swap and same turbo kit?
The build fieroguru described is his blue car with the LS4/F40. I think the auto he was going to do is in storage, and he was going to keep it stock to try to get it swapped with as few custom parts as possible.
The orange Murci that dratts had? Or another Murci with the same swap and same turbo kit?
I don't know who dratts is or where he lives, but our member bought his unfinished Murciélago kit car from someone who was also here in Québec, if my memory is right. It still had a stock 88 Fiero GT powertrain that wasn't working when he purchased it. Our member then performed the LS4 swap and the turbocharging.
------------------ Silver 88 coupe, Duke with TH125C (for now) White 88 GT, 3800 L67 with 4T65E-HD (sold) White 91 Cadillac DeVille (winter beater and possible swap donor)
