I am building a 4.9 right now that will be mated with an F40 trans. I am most certainly know the 4.9 has its limitations. I already had this motor from a parts car so I figured why not. What I have done is:
1. Allante Intake and steel rocker arm supports 2. Delta cam 3. Johns longtube headers 4. Ported the heads myself and cut the valve seats for better springs to get rid of that choke point that the 4.9's suffer from. I took out almost 2lbs of material on each head. 5. Sinister tuning for the use of the allante intake and other odds and ends. (not really performance but annoying check lighys or limp mode)
I am not expecting miracles but I am sure this motor will be a blast to drive till I swap in something more modern down the road. Build whatever you want and your finances can handle.
Originally posted by Mickey_Moose: The time an money I spend on my car didn't really make it a performer.
What expectations did you have?
From what I see on the present quarter mile list, it seems like slightly warmed over Cadillac 4.9s (naturally aspirated) should be in the high-13 / low-14 range... which for some people could be considered entertaining.
"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
I have it from an extremely reputable source that the engine bay of the Fiero was designed from the very beginning for a transverse aluminum V-8.
The only transverse aluminum V-8 that GM had during the early stages of the Fiero design phase was made by Cadillac.....the 4.1.....
There are two signatures on my car. One of the signers is the source of that information, and was involved with the P-car project from the beginning.
I am building a 4.9 right now that will be mated with an F40 trans. I am most certainly know the 4.9 has its limitations. I already had this motor from a parts car so I figured why not. What I have done is:
1. Allante Intake and steel rocker arm supports 2. Delta cam 3. Johns longtube headers 4. Ported the heads myself and cut the valve seats for better springs to get rid of that choke point that the 4.9's suffer from. I took out almost 2lbs of material on each head. 5. Sinister tuning for the use of the allante intake and other odds and ends. (not really performance but annoying check lighys or limp mode)
I am not expecting miracles but I am sure this motor will be a blast to drive till I swap in something more modern down the road. Build whatever you want and your finances can handle.
I'm curious about what numbers your build ends up producing. Are you going to have it dyno tuned? What ECM? What flywheel, for that matter?
From what I see on the present quarter mile list, it seems like slightly warmed over Cadillac 4.9s (naturally aspirated) should be in the high-13 / low-14 range... which for some people could be considered entertaining.
You wanted something quicker than that?
I had no expectations, just wanted a project and came across a 4.9l that was cheap. Figured I would add the go fast stuff while it was apart. Don't get me wrong it was a fun car. Was in the low 14's when I took it to the track and would dominate a lot of cars for the first 1/4 - 1/2 of the 1/4 mile track.
I was perfectly fine with the 4.9l (since I built the car mainly as a daily driver with some track time - actually became a perpetual project with the f-body interior work, etc), but the OP seems to want a lot more (money is no object), and that is not going to happen with the 4.9l. As I said in my post a 3800SC Fiero would take the car in a 1/4 mile race.
Just trying to keep it real and if money was no object, there are easier ways get get more power into a Fiero.
[This message has been edited by Mickey_Moose (edited 08-14-2020).]
I am building a 4.9 right now that will be mated with an F40 trans. I am most certainly know the 4.9 has its limitations. I already had this motor from a parts car so I figured why not. What I have done is:
1. Allante Intake and steel rocker arm supports 2. Delta cam 3. Johns longtube headers 4. Ported the heads myself and cut the valve seats for better springs to get rid of that choke point that the 4.9's suffer from. I took out almost 2lbs of material on each head. 5. Sinister tuning for the use of the allante intake and other odds and ends. (not really performance but annoying check lighys or limp mode)
I am not expecting miracles but I am sure this motor will be a blast to drive till I swap in something more modern down the road. Build whatever you want and your finances can handle.
Share some pictures of you head work, please! although it was never a performance oriented motor, i do have a soft spot for "bad" engines made better.
Hey guys, sorry I haven't responded recently, been hard at work with my business the past two days!
I'm not looking for mega power, by no means do I expect to make 3800 power with a 4.9l Cadillac. What I am looking for is more power than the stock engine (check) and an awesome sounding V8 (check again). That's the primary reason I'm looking at the 4.9L, or a similar sized V8. I love everything I'm seeing with the 4.9L so far.
OleJoeDad: I am not at all suprised to hear this info. After seeing the pictures of the 4.9L in the Fiero engine bay, it completely looks like it belongs in there!
Not getting dyno tune specifically, but I do want to get it dyno'd when finished because I am curious what the final numbers will be. I am sticking with the stock ECM right now. I may choose something different later. I do have a 7730 sitting on the shelf and I also could just go with a stand alone as well. I am using the flywheel that came with the car originally. It was a Fiero Factory swap before I got it, so whatever they used. John goes that extra mile with his bigger valves, I just do not have the means to handle that.
Here are some quick head comparison photos:
Here is how it looks right now:
[This message has been edited by Spadesluck (edited 08-16-2020).]
Not getting dyno tune specifically, but I do want to get it dyno'd when finished because I am curious what the final numbers will be. I am sticking with the stock ECM right now. I may choose something different later. I do have a 7730 sitting on the shelf and I also could just go with a stand alone as well. I am using the flywheel that came with the car originally. It was a Fiero Factory swap before I got it, so whatever they used. John goes that extra mile with his bigger valves, I just do not have the means to handle that.
I hope you paid the same level of effort to the intake manifold, the runners have to wrap around the pushrods there, and that is where a flow restriction will be. A lot of people claim its not a restriction, but every time mass has to change direction, it must be accelerated, that requires energy, and it will be pulled out of the air, costing velocity.
Originally posted by Spadesluck: ... Here is how it looks right now:
Are you installing the F40 "as equipped"?
I am very intrigued by Fieroguru's 3.09 FDR swap. Priced a few UK F40s this morning. The most expensive one was, I think, ~100 pounds, UK. Shipping would have to be a heller, though.
I am very intrigued by Fieroguru's 3.09 FDR swap. Priced a few UK F40s this morning. The most expensive one was, I think, ~100 pounds, UK. Shipping would have to be a heller, though.
As is, I am not that deep in the pockets to try that adventure.
I hope you paid the same level of effort to the intake manifold, the runners have to wrap around the pushrods there, and that is where a flow restriction will be. A lot of people claim its not a restriction, but every time mass has to change direction, it must be accelerated, that requires energy, and it will be pulled out of the air, costing velocity.
The Allante intake is very well built honestly. I did port it some to match the heads but there was not much work to be done. If you have ever had the chance to look at one you will understand there is a big difference between the stock intake and Allante setup.
I've done some head work. 1.94 and 1.60 stainless steal valves. Cheers
quote
Originally posted by Spadesluck:
Not getting dyno tune specifically, but I do want to get it dyno'd when finished because I am curious what the final numbers will be. I am sticking with the stock ECM right now. I may choose something different later. I do have a 7730 sitting on the shelf and I also could just go with a stand alone as well. I am using the flywheel that came with the car originally. It was a Fiero Factory swap before I got it, so whatever they used. John goes that extra mile with his bigger valves, I just do not have the means to handle that.
Here are some quick head comparison photos:
Either of you guys get your heads on a flow bench?
The Allante intake is very well built honestly. I did port it some to match the heads but there was not much work to be done. If you have ever had the chance to look at one you will understand there is a big difference between the stock intake and Allante setup.
I agree. It has to be a quantum leap above the stock 4.9.
I find the Allante setup to be very much like a TPI, except with even longer runners - by a significant amount. (I jokingly call it a "folded TPI".) "John's 4.9" has designed a short runner upper intake for the Allante lower. It really looks promising, especially if there's some good head/valve work done, to complement it.
No, I did not do any flow testing as this was just all done in my garage. This has been a learning experience for me being only my second head porting I have done. Only thing I did was weight the heads before and after just to see how much material was removed. Ironically I removed the exact same amount on both heads, 1.3lbs each. M goal is not to set the world on fire, just to learn and have fun with it.
[This message has been edited by Spadesluck (edited 08-19-2020).]
I agree. It has to be a quantum leap above the stock 4.9.
I find the Allante setup to be very much like a TPI, except with even longer runners - by a significant amount. (I jokingly call it a "folded TPI".) "John's 4.9" has designed a short runner upper intake for the Allante lower. It really looks promising, especially if there's some good head/valve work done, to complement it.
MaxCubes used an Allante lower to mount is supercharger as well.
I like the Allante lower manifold. I have used it for my supercharger build as well as my fuel injection set up. This engine has the big valve heads and 180 degree headers with duals. Cheers
Hey Darryl, Thank you for visiting my website. Estimating horsepower is a touchy subject. I hate throwing numbers out there. But my engines are built for road racing and autocross. I am more in to great handling and braking then I am about quarter mile speeds. So the square bore and stroke, 3.62, of these engines is never going to see high horsepower and high revs over 6200. The 4.9 engines is a good choice for a sports car but really not much of a dragster engine. So if your concerns are quick quarter mile speeds, you are better off with a different engine. But for handling and spirited driving, I like the torque and light weight of the 4.9 engine. Cheers, John
That's exactly what I'm looking for John, and also why I was looking towards the 4.9L as my first choice. I keep asking about power because, as someone from a drag racing family, power's always been my main metric. Let me specify a little more so i sound more reasonable: I'm only hoping for between 300-400hp max. I assume 300 is doable, only 100 more than the stock rating.
I think 300 hp is the top power possible being normally aspirated. You 400 hp goals would have to be a boosted engine. But I'm working on that also with a boosted 4.5 engine. The 4.5 has a shorter stroke and lighter crankshaft then the 4.9 and has the potential for more revs than the 4.9 engine. John
That's good to know! I wouldn't mind a turbo, providing the engine could handle the boost without sending the rods into orbit, but on the same side of the coin the added weight of a proper turbo setup is something I'd like to avoid. Keep the car light and it ought to corner better.
the added weight of a proper turbo setup is something I'd like to avoid. Keep the car light and it ought to corner better.
Keep in mind that the 4.9 weight is within shouting distance of the stock 2.8. Some people say it's about the difference of the weight of an A/C compressor. Others don't even go that far.
Another big reason I'm specifically looking at the 4.9L over the other obvious V8 options: the weight of the engine. I think I read that the 4.9L is a whopping 5 pounds heavier than the factory V6
I think 300 hp is the top power possible being normally aspirated. You 400 hp goals would have to be a boosted engine. But I'm working on that also with a boosted 4.5 engine. The 4.5 has a shorter stroke and lighter crankshaft then the 4.9 and has the potential for more revs than the 4.9 engine. John
Stroke has very little to do with the ability of street engines to "REV" its has everything to do with airflow and camshaft timing, Neither of which this platform is designed for. What will happen, is with an identical top end, the lower displacement engine will achieve peak power and torque at a higher RPM. This has been proven time and time again the dyno.
Wear and tear is a factor, but it's affect on power production, as far as street engines are concerned, is effectively nil.
My point is, there is rarely ever a reason to not go with the maximum displacement possible. it makes reaching the desired power goal much easier, since engine speeds can be lower to achieve the needed airflow for a certain power level, provided you have the top end airflow (read: mass-flow) needed to reach that power level.
[This message has been edited by FieroWannaBe (edited 08-18-2020).]
Originally posted by Reborn756: Let me specify a little more so i sound more reasonable: I'm only hoping for between 300-400hp max. I assume 300 is doable, only 100 more than the stock rating.
Well if you're throwing out the stock heads and using custom-made billet heads, then the flow limitations of stock 4.9 (or stock-based) heads no longer apply to you. The sky is the limit.
quote
Originally posted by Reborn756: the added weight of a proper turbo setup is something I'd like to avoid. Keep the car light and it ought to corner better.
Using my personal Fiero as an anecdote...
I'd guess that bolting on a turbo increased my car's overall weight about 1.5% (maybe less), but power may have increased 50%. In my mind, the choice wasn't hard...
I think the biggest downside of a turbo is slow throttle response.
Hey Darryl, Thank you for visiting my website. Estimating horsepower is a touchy subject. I hate throwing numbers out there. But my engines are built for road racing and autocross. I am more in to great handling and braking then I am about quarter mile speeds. So the square bore and stroke, 3.62, of these engines is never going to see high horsepower and high revs over 6200. The 4.9 engines is a good choice for a sports car but really not much of a dragster engine. So if your concerns are quick quarter mile speeds, you are better off with a different engine. But for handling and spirited driving, I like the torque and light weight of the 4.9 engine. Cheers, John
Spin some rollers so you don't have to estimate.
quote
Originally posted by FieroWannaBe:
Stroke has very little to do with the ability of street engines to "REV" its has everything to do with airflow and camshaft timing, Neither of which this platform is designed for. What will happen, is with an identical top end, the lower displacement engine will achieve peak power and torque at a higher RPM. This has been proven time and time again the dyno.
Wear and tear is a factor, but it's affect on power production, as far as street engines are concerned, is effectively nil.
My point is, there is rarely ever a reason to not go with the maximum displacement possible. it makes reaching the desired power goal much easier, since engine speeds can be lower to achieve the needed airflow for a certain power level, provided you have the top end airflow (read: mass-flow) needed to reach that power level.
92mm is the stock stroke of the 5.3, 5.7, 6.0 & 6.2 displacements of the LS family of engines... no one says they can't turn over 6200. RPM is all about displacement vs. airflow.
quote
Originally posted by pmbrunelle:
Well if you're throwing out the stock heads and using custom-made billet heads, then the flow limitations of stock 4.9 (or stock-based) heads no longer apply to you. The sky is the limit.
Heh... maybe yes, maybe no. I'll draw a parallel with a friend who wanted to turn a GenII V6/60 to 8000 RPM. Sure, the components are out there to build a valvetrain that will do it. A pushrod valvetrain that will turn that RPM is going to cost as much as the rotating assembly, though. The real kicker is that once the valvesprings are stiff enough to control the valvetrain at that RPM, there's a very real chance of breaking the rocker boss off the cylinder head. What do you do then? You're done. You've spent a lot of money and you're just not going to hit your goal. Full stop.
The same applies to radically upgrading any one part of an engine. Say OP does have 350+ CFM billet heads cut for the 4.9. Being designed from scratch, they would naturally have strong enough rocker bosses to turn 8000+ RPM, which is what the airflow in such heads would allow for a ~5 liter engine. Remember, GM put their first 350 CFM heads on a SEVEN litre engine and spun it to 7000 RPM. So now you have a top end that will flow air for 8000 RPM, you'll need a cam that will open the valves to allow the engine to make power at that RPM and a valvetrain that will turn that RPM. Since no one makes 4.9 cores, you're buying a billet cam. Is the timing chain up to turning that load at 8000 RPM? Is the rotating assembly up to it? You'll need rods & pistons, which is really rods & rod bolts & pistons & pins & locks & rings & bearings... What if you do all that and the oiling system in the block just can't move enough oil at enough pressure to keep the assembly lubricated? Dry sump? How much 4.9 is left after all that? It certainly wasn't a cheap swap at that point, and for the money spent there would be lighter options that would make more power.
Not stroke, bore to stroke ratio. Physic still applies to a reciprocating engine. A Ford 302 will spin better because it has a shorter stroke and larger bore than the 4.9 engine. Almost the same displacement. A Ford 302 is 4" bore and 3" inch stroke. Less piston speed per stroke in the 302.
Not stroke, bore to stroke ratio. Physic still applies to a reciprocating engine. A Ford 302 will spin better because it has a shorter stroke and larger bore than the 4.9 engine. Almost the same displacement. A Ford 302 is 4" bore and 3" inch stroke. Less piston speed per stroke in the 302.
The LS7 made peak power (6300) and torque (4800) at a higher RPM than any other previous GENIII/GENIV V8 from Chevy. It does that with a 4.0" stroke. It's 100% a function of the top end.
If I am trying to compute how efficient an engine is, I do not need to know at any time what it's stroke is, I need to know how efficiently it can move air.
Fords 302 has larger heads and cams available that will allow the engine to breath enough air to produce high power, and the cams have timing favorable for high RPM.
Nothing about the stroke of the 4.9L will limit its ability to make high RPM power, everything about the available camshaft heads and intakes will, and they don't change at all in the 4.5L.
The LS7 made peak power (6300) and torque (4800) at a higher RPM than any other previous GENIII/GENIV V8 from Chevy. It does that with a 4.0" stroke. It's 100% a function of the top end.
If I am trying to compute how efficient an engine is, I do not need to know at any time what it's stroke is, I need to know how efficiently it can move air.
Fords 302 has larger heads and cams available that will allow the engine to breath enough air to produce high power, and the cams have timing favorable for high RPM.
Nothing about the stroke of the 4.9L will limit its ability to make high RPM power, everything about the available camshaft heads and intakes will, and they don't change at all in the 4.5L.
The LS7 has a 4.125 bore and 4" stroke... so it's NOT very oversquare. NHRA Mountain Motors turn 8500ish RPM with strokes approaching 6 inches and are UNDERsquare.
Turning up and making power is about breathing, which is why the focus area in 4.9 performance is rightly on the heads and cam.
The LS7 has a 4.125 bore and 4" stroke... so it's NOT very oversquare. NHRA Mountain Motors turn 8500ish RPM with strokes approaching 6 inches and are UNDERsquare.
Turning up and making power is about breathing, which is why the focus area in 4.9 performance is rightly on the heads and cam.
One cannot forget the intake. I believe it is where the real restriction lies in this engines, since they route the runners around the pushrods, forcing the air to accelerate twice, and then make the short radius turn into the valves. They air loses a lot of energy. You can see how the engineers curved the center ports in the head and intake to try to work around that. The standard TBI intake has very small ports and a dual plane setup. It is set up for low speed torque, and short of re-fabbing entirely it is stuck that way. The Allante intake is very similar in setup to the TPI intake, very long skinny runners. Shortening them with and porting combined with a larger plenum will help shift the power curve, but it really needs to match the cam installed. I have a old 4.5l I decided to not swap years ago because after looking at all this, I just couldn't see it meeting my power goals per dollar spent. At the time 250whp NA seemed like it was almost too much work with available components at the time (2008-ish) But it is possible, if the entire top end is designed with a common goal in mind. Cam, Intake, Heads.
So, given all of the information presented thus far, it seems my idea of finding a machine shop to build a custom set of heads is the right direction. Now to find someone willing enough to eventually take my money and do it.
So, given all of the information presented thus far, it seems my idea of finding a machine shop to build a custom set of heads is the right direction. Now to find someone willing enough to eventually take my money and do it.
It would be foolish not to acquire and dissect a set of factory heads first. Actually the project would be impossible without doing so.
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