Thoughts on supercharging 4.9
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HT4100 4.1, 4.5, 4.9 Discussion, Thoughts on supercharging 4.9 in Cadillac Engine Technical Discussion; I'm looking into putting an Eaton Supercharger off of a 3.8 V6 on a 4.9 motor, but I can't find ...
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    the recluse is offline Cadillac Owners Connoisseur
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    Thoughts on supercharging 4.9

    I'm looking into putting an Eaton Supercharger off of a 3.8 V6 on a 4.9 motor, but I can't find the specs for any of them. I need the specs (length, height, pulley spacing, etc.) for the '92 to '95 Eaton and the redesign from '96 to '02.

    I need them to see feasibility and know I've got to fab my own manifold. Any other thoughts on the matter?

    Thanks guys...

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    steelybill is offline Cadillac Owners Enthusiast
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    Re: Thoughts on supercharging 4.9

    A friend has one of those on his '94 Bonneville with the 3800 (Buick) engine. I would think that the electronics control that item along with the rest of the management system.
    Since that engine is smaller, more over-drive RPM on the supercharger may be needed for a 4.9.

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    the recluse is offline Cadillac Owners Connoisseur
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    Re: Thoughts on supercharging 4.9

    Quote Originally Posted by steelybill View Post
    A friend has one of those on his '94 Bonneville with the 3800 (Buick) engine. I would think that the electronics control that item along with the rest of the management system.
    Since that engine is smaller, more over-drive RPM on the supercharger may be needed for a 4.9.
    I don't think the supercharger is electronic controlled, just the fuel management system; which a flash of the ECM should cure.

    I thought about the over-drive RPM and since the system (4900 to 5000 rev limit on tranny) is computer limited, I'm wondering what RPM the powerband would show up in...Gotta crunch numbers.

    The likeable thing is this particular supercharger is it's relatively cheap and mass produced with serviceable parts as well as looks like it would fit quite nicely on the motor...

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    drewsdeville is offline Cadillac Owners Master
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    Re: Thoughts on supercharging 4.9

    With respect, I'd advise against putting that kind of time and effort into a 4.X for performance. You most likely aren't going to get what you are looking for. It's nice to see some 4.X enthusiasm around, but it's not worth it.

    Even cleaned up, these heads are extremely restrictive and can't flow a decent amount of air. they weren't made to flow air, it's target service being heavy luxo-boats that needed some low end torque to get moving. A supercharger won't make up for tiny valves and poor geometry. Even if you bumped it up 100 hp after all of this work, which is overly-optimistic, you could have purchased a cheap northstar powered Caddy and got the same results.

    Just food for thought.

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    Re: Thoughts on supercharging 4.9

    I agree with drew on the power vs. cost/effort value but in my opinion, having something that no one else has and being the first to do it is where the value is. I'd say this one is a little more feasible than turbocharging due to the custom exhaust work required. At least the manifold is easier to get to which of course will be quite the challenge in itself. All other things aside, I think you will have hood clearance issues unless you could design and cast a bolt in replacement for the original manifold which is probably next to impossible. The only way I could see it happening is with a low profile adapter that replaces the throttle body, but then of course you have to relocate the TB, all vacuum lines and all 3 cables... Unless you make a blow-through design and leave the TB alone but then of course where do you put the blower? Not much room to work with. Hmm, maybe a turbo IS easier.

    And then theres the engine management hurdles... for one thing, you need a MAP sensor that can see boost pressure. The oem only sees vacuum. Are there provisions in the computer that would register positive pressures? Of course it wouldnt know what to do with them in the first place without a re-flash but THEN the question is to WHAT do you re-flash the stock values to? The engine that was made for that blower probably spent hours on a dyno with a team of specialists. Even if you have a way to re-flash the PROM (which is a formidable challenge all by itself), what is the chance that you're going to get it right the first time?

    And something else that sucks: the stock compression ratio is already pretty high for a passenger car at 9.5:1 so there isnt a whole lot of room in the combustion chamber for boost. And the stock pistons are CAST aluminum btw And lastly, a root-style blower makes its boost down low and the 4.9 is already known for it's low end grunt so I think by the time you could really use the extra boost , the engine is already beyond it's powerband and as the blower spins faster it needs more and more power exponentially to make that boost. I think if any super charger was a match for that engine it would be a centrifugal type but of course there is absolutely nowhere to put it. When I started this post I thought the supercharger would be easier but by this point I'm more in favor of the turbo!

    There is a guy by the name of Mark97STS (I think) who managed to turbo a northstar... I think it ran 10' or 11's cant remember. I know its a different engine but at least it IS possible to hack and boost an engine that absolutely wasnt designed for boost. However I know that he spent over 10 grand on the project (and later his wife wrecked it ) Hmm now that I think about it I believe he built the bottom end of the motor and lowered the compression ratio. Cant remember...

    I not saying it cant be done or it's a stupid idea... I think a supercharged 4.9 caddy would epic but it looks to me like one HELL of a challenge.

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    the recluse is offline Cadillac Owners Connoisseur
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    Re: Thoughts on supercharging 4.9

    Quote Originally Posted by drewsdeville
    With respect, I'd advise against putting that kind of time and effort into a 4.X ... You most likely aren't going to get what you are looking for.
    I'm not expecting much, just looking to push a little motor a little farther

    Quote Originally Posted by drewsdeville
    Even cleaned up, these heads are extremely restrictive and can't flow a decent amount of air.
    I noticed that when I was porting them; the outside ports were big and spacious whereas the inner ports were confined. I am curious as to what the CFM numbers would be on these heads


    Quote Originally Posted by Sevillian273
    And something else that sucks: the stock compression ratio is already pretty high for a passenger car at 9.5:1 so there isnt a whole lot of room in the combustion chamber for boost. And the stock pistons are CAST aluminum btw
    The compression was a pausing point for me also as I would like it around 8.5:1 with a shade more duration on the cam but I figured if you can turbo it, you can supercharge it.

    Quote Originally Posted by Sevillian273
    ...a root-style blower makes its boost down low and the 4.9 is already known for it's low end grunt so I think by the time you could really use the extra boost , the engine is already beyond it's powerband
    The other reason I would like more duration on the cam and better flowing heads as Drew pointed out.

    As always, I take criticism with a grain of salt. I find round table discussions bring out the best(and worst) of every idea. This idea may just be like the chick you want to bed down after 15 shots, but by morning when the haze clears; not so much

    I may revisit this over time while I address some issues and as always, thanks for the input

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    Re: Thoughts on supercharging 4.9

    My partner has the front end apart on his Bonneville, for replacing a core support member, and he is talking about an exchange super charger, since it has some noise in the pulley end. If he does that I'll get some pics of the manifold and the bottom of the blower etc for future reference.

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    the recluse is offline Cadillac Owners Connoisseur
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    Re: Thoughts on supercharging 4.9

    Thanks guy, and throw a tape measure next to it so I can see what I'm up against.

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    Ghost C's Avatar
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    Re: Thoughts on supercharging 4.9

    Centrifugal would be your best bet, if you can live without A/C you could easily fab up a mount in that area. Plenty of room to run the piping, make mounts, adapters, etc. Turbo is much simpler - Cap the rear center outlet on the manifold, weld a flange onto the crossover pipe and you're pretty much in business - But I believe you'd have the first supercharged 4.9 which would add major cool points, someone correct me if I'm mistaken.

    Quote Originally Posted by drewsdeville
    Even cleaned up, these heads are extremely restrictive and can't flow a decent amount of air. they weren't made to flow air, it's target service being heavy luxo-boats that needed some low end torque to get moving. A supercharger won't make up for tiny valves and poor geometry. Even if you bumped it up 100 hp after all of this work, which is overly-optimistic, you could have purchased a cheap northstar powered Caddy and got the same results.
    The heads aren't great at flowing, which is why boost makes so much power on these motors. 100hp isn't overly optimistic, it's been done several times with low boost turbo setups. I don't see why a supercharger would be any different. If everyone just bought a car that came stock with more horsepower when they wanted performance, we'd all be driving Z06's, GT-R's and the like. Where's the fun in that? Anything can be done with these old FWD luxury boats - I got a full sponsorship from Energy Suspension and was offered a partial from Moton. Yes, the Moton that makes dampers for FIA racecars, Ferraris, etc. Anything can be done.

    Also, someone said something about a MAP that senses boost. GM makes one, it goes right in, comes in 1 bar and 2 bar of boost, 1 bar would be plenty. I believe the 1 bar MAP uses the same output parameters as the stock MAP but isn't as good because the same outputs have to cover a wider range, or something of the sort... It was explained to me once, and if I had my old computer still I'd copy the e-mail over here. I know it was one of the Fiero guys, so try looking at the 4.9 builds over at Pennock's Fiero Forum for help.

    Don't worry too much about the compression, as long as you use good fuel and don't try to make 500whp, you'll be fine. The 4.9 is exceptionally robust.

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    drewsdeville is offline Cadillac Owners Master
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    Re: Thoughts on supercharging 4.9

    Quote Originally Posted by Ghost C View Post



    The heads aren't great at flowing, which is why boost makes so much power on these motors. 100hp isn't overly optimistic, it's been done several times with low boost turbo setups. I don't see why a supercharger would be any different. If everyone just bought a car that came stock with more horsepower when they wanted performance, we'd all be driving Z06's, GT-R's and the like. Where's the fun in that? Anything can be done with these old FWD luxury boats - I got a full sponsorship from Energy Suspension and was offered a partial from Moton. Yes, the Moton that makes dampers for FIA racecars, Ferraris, etc. Anything can be done.
    Definitely anything can be done, albeit with enough resources (time and money)involved.

    A performance 4.9 just can't be a good value for the money, that's all. Like you said, some have achieved 300hp on a 4.9. But is that impressive? Not really. Any way you look at it: HP per dollar, HP per ci, HP per mpg, the 4.9 will lose to most. Personally, I like to maximize horsepower just like anyone else. But is it really rewarding to break the bank for a measly 300 horses? While the 300hp is 50% more than a stock 4.9, it's not much out in today's real world.

    Northstar powered cars make 300hp and can't even break out of the 15's without some hefty modification... So you could double the hp from 200 to 300 and still have a slow car.

    And regarding the cost, it's never wise to stick more money into a car than it's worth. It's just too risky. The OP is talking about a 20 year old Eldorado. The car isn't worth much more than $2k. If you stick a couple g's into it, wreck it the following week, the insurance company isn't going to reimburse you for those thousands in mods...

    Anyway, to the OP, I just want to make sure that you thoroughly think about what you are getting into and weighing the pro's and con's of it all. If you decide you still want to go for it, I'll be keeping up with your threads watching the progress as it should be a fun and interesting project.

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    the recluse is offline Cadillac Owners Connoisseur
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    Re: Thoughts on supercharging 4.9

    Just to clarify, the supercharger 4.9 project would probably be going in a Firebird, not a Caddy, as the motor should bolt right up to the V6 tranny and weighs the same. I will have V8 power with the V6 weight and a Caddy powered Pontiac

    That said, if I happen to work the bugs out of the build and decide to mod out my Eldorado, so be it.

    Quote Originally Posted by drewsdeville
    And regarding the cost, it's never wise to stick more money into a car than it's worth. It's just too risky.
    Believe me I understand this one...but EVERY car is money pit and a losing proposition from the start and one will never get any money back that is spent. An $8000 paint job (paint just being an example) can/will get scratched whether it's on a Porsche or a Honda.

    Any project car is technically a waste of money as well as any mods done to any car. Fortunately, I've found that knowing people and having access to machining equipment, in this instance, should save me a lot of money; it's the expertise/experience in all aspects of these motors/computer systems that I lack.

    With the open bay of the Firebird, I would also like to mock up some headers, as well as intake modifications and the like...I'm curious as to what these motors can actually put out, and if it breaks, well, the motors are relatively cheap because no one really wants them...

    Thanks again guys for your input...

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    ehall's Avatar
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    Re: Thoughts on supercharging 4.9

    Nobody wants them because they're half aluminum. They are born as curiosities and die as circus freaks.

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    MaxCubes is offline Cadillac Owners Member
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    Thumbs up Re: Thoughts on supercharging 4.9

    The 4.9 is a VERY popular engine swap in Fieros...

    ... Here is a picture of one in my Fiero...

    and YES, it is supercharged with an Eaton M90

    528396_247385975405534_1041710668_n.jpg


    Some videos...

    http://youtu.be/ULmbjJ92K_E

    http://www.youtube.com/watch?v=K9iE0PhoiOk

    http://www.youtube.com/watch?v=8qphRaCd8UY

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