ok i am still not sure what to with my 88 coupe... the car is being built as a project for my wife..she has no idea its a surprise..the car is a 5 spd not many options but thats minor im adding the pwr goodies all in..i am still undecided wtf to put in it for an engine...i already have a 3.8sc car so thats a been there done that conversation...so ive sorta narrowed it down to 4.9 OR THE 3.4 DOHC engine..i have access to both very cheap... just wondering of the fitament issues of both... i have done some 4.9 research but not a lot on the 3.4 dohc... so 3.4 dohc guys speak up...lol thanks tim..

Nah..

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1988 Pontiac Fiero -

quote Originally posted by thismanyfieros: ... i have done some 4.9 research but not a lot on the 3.4 dohc... so 3.4 dohc guys speak up...lol thanks tim..

I've heard second hand that the 3.4 DOHC has more fitment issues compared to the 4.9. But take that with a grain of salt since I've never done one.

However, I can tell you that the 4.9 fits like it belongs there, even in an 88, and only requires very slight modification to the right hand decklid hinge for it to fit.

[This message has been edited by jscott1 (edited 03-14-2009).]

The 4.9 seems to be more of a daily driver engine. It is very smooth, good torque and pulls through all the gears. Not a screaming performance engine the 3.4 tdc is. Also, maintanence is much lighter on the 4.9, the 3.4 requires constant attention. Both, if taken care of and treated right will last 250,000+ miles. However you will spend a bunch more on the 3.4. But the 3.4 has more fun factor to it and will rev all day long, the 4.9 will not. For me, I would do a 3.4 tdc swap, but for the misses, she would get the 4.9. She loves to cruise and the 4.9 is perfect for it. And I hit the corners with no regard for my personal safety, so the 3.4 is the better option. I also think the 4.9 will get a bit better gas mileage.

I was helping out a local member reinstalling her DOHC. That is a BIG motor. It has 1/4 inch tolerances all around. No joke.

I do love the way that motor sounds. Not to mention the never-ending revs.

The dohc fits on the stock v6 engine mount and even uses the stock v6 mount bracket. You just have to trim the passenger side decklid hinge mount and give up one of the decklid spring. Its a big motor but fits just fine. GM was planning on using it in the 1989 Fiero

I have been using mine as a daily driver for 4 yrs and still get excited everytime I drive it. Its a great engine, fits the Ferrari like nature of the Fiero very well

I do not recommend using an auto with it as it takes away from the fun factor. The engine spins to 7000rpm and with an auto it is limited to lower rpm or it can kill the trans at least with the stock 4t60-e it comes stock with in the W body.

I have gotten up to 30 mpg driving very conservatively with a 4.10 4 speed. You could get that with more spirited driving with a taller FD. Typically I get 20 to 24 mpg driving it like I stole it

I think you might like the high rev DOHC since you already have a lower end torque type engine already in the 3800SC

[This message has been edited by Erik (edited 03-14-2009).]

quote Originally posted by topher_time: The 4.9 seems to be more of a daily driver engine. It is very smooth, good torque and pulls through all the gears. Not a screaming performance engine .

Is this opinion based on personal experience, or just from reading the forum?? I disagree. The 4.9 is a beast... When you start it up there is no doubt it's a V8. It's not the fastest engine in the 1/4 mile, but few cars can beat a 4.9 powered Fiero on the street. It is smooth, but it is also a very fast engine at street legal speeds.

Hmm my 308 rebody with a 4.9 must have been a real dog. Shipped it from Texas to CA, Shipped it to Australia, picked it up 3 hours from home on a car trailer and bought it home.

Drove it around the block and thought what a POS. Put it on ebay and sold it.

So that is my opinions of 4.9s after bringing one half way around the world.

The two engines are totally different. The 4.9L gives lots of low end torque while the 3.4 TDC makes most of its power up high. One is a low RPM torque engine designed for a luxury sedan, highway cruising and good mileage the other is a high RPM engine with characteristics better suited to sports car driving. Both will make for an economical swap but both also lack very much of an aftermarket for performance parts. Both of these engines were designed for everyday driving but of the two I would say that the 4.9L is more reliable. I've had rides in Fieros with both engines and its like comparing apples to oranges.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE WILDCAT"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

quote Originally posted by Dennis LaGrua: The two engines are totally different. The 4.9L gives lots of low end torque while the 3.4 TDC makes most of its power up high. One is a low RPM torque engine designed for a luxury sedan, highway cruising and good mileage the other is a high RPM engine with characteristics better suited to sports car driving. Both will make for an economical swap but both also lack very much of an aftermarket for performance parts. Both of these engines were designed for everyday driving but of the two I would say that the 4.9L is more reliable. I've had rides in Fieros with both engines and its like comparing apples to oranges.

Probably the best comparasion I've read so far. Different engines for different applications. What's the best engine for her driving style? Is she a cruiser an auto-crosser, a road ralley racer, drag racer? What transmission are you going to mate to this engine? Makes a big difference in performance as is mentioned above.
I've got six 88 Formulas here and one 88 Coupe, they have different combinations of engine/trannies. Each one has it's strong points and it's weak points. Eventually, I'll figure out which combination fits my needs. At least that's what I keep telling my wife.

Ron

[This message has been edited by blackrams (edited 03-14-2009).]

quote Originally posted by jscott1: Is this opinion based on personal experience, or just from reading the forum?? I disagree. The 4.9 is a beast... When you start it up there is no doubt it's a V8. It's not the fastest engine in the 1/4 mile, but few cars can beat a 4.9 powered Fiero on the street. It is smooth, but it is also a very fast engine at street legal speeds.

Experience. What I think is quick or fast and what someone else does is totally relative to what they have experience driving. Drive a Jaguar S-Type R and then the 4.9 Fiero; you might be disappointed. Difference between fast and quick. I tend to compare cars to cars, doesn't matter if it's powered by a 3 cylinder or quad turbo W16. I shouldn't, but I do.
First 4.9 Fiero 5 spd I drove came shortly after driving a Mustang with 1000 hp for a few hours. Big difference, the 4.9 felt vague and unresponsive compared to a 5.4 dohc twin turbo engine. Second one was an auto, quite a bit different compared to a stick shift, felt more like it stayed in the power curve instead of trying to find it using poorly matched gearing in a stick. Still felt like a cruising engine, exaclty what it was built for, the older Cadillacs were never ment or tried to be sports cars.

quote Originally posted by topher_time: First 4.9 Fiero 5 spd I drove came shortly after driving a Mustang with 1000 hp for a few hours. Big difference, the 4.9 felt vague and unresponsive compared to a 5.4 dohc twin turbo engine..

While I somewhat agree with your point, that's not exactly a fair comparasion.

Ron

it would just be a fart around in town kind of car for her...she does like to embarass unsuspecting ricers and older muscle cars with my 3.8sc car...she even admitted wasting a bread truck one day...lol so she has no mercy behind the wheel...glad ive taught her well...the more i hear the more im leaning 4.9...i only considered a 3.4 dohc cuz yesterday at the pick and pull i saw 2 complete low kms engines...and it wouldnt cost much to get one..i appreciate all the comments...keep them coming....tim

I have most of the items needed for a 4.9 swap at home now. I have found a whole 91 Deville and bringing it home before April 1st. Let the fun begin

Joe

quote Originally posted by topher_time: Experience... ... Still felt like a cruising engine, exaclty what it was built for, the older Cadillacs were never ment or tried to be sports cars.

Fair enough you have driven one, but this thread is not comparing the 4.9 to a 1000 hp twin turbo mustang.

I'm not saying the 4.9 is my first choice for a race car, maybe not even on the list. But as an upgrade to the 2.5 or 2.8 it's in the same ballpark as the 3.4 DOHC.

Sure it doesn't rev as high as a DOHC, but you don't need it. Maybe I'm not as experienced driving high performance race cars, but I don't feel any vagueness and unresponsiveness in the 4.9. When I punch it, you better be holding onto something.

I've driven both 4.9 and 3.4 DOHC Fieros and they're both tons of fun, but in different ways.
I think the 3.4 is better suited to a stick shift, and the 4.9 is better suited for an automatic. Just personal impression, but the 4.9 feels more like a point and shoot straight line car, and the 3.4 feels more at home on long twisty roads where you can stretch out each gear.

You can do a 4.9 stick no problem. The one I drove had a 4.10 4-speed in it. Yeah, can you say LEAP off the line! Gotta be fast on the clutch, though, because those gears don't last long.
But I would absolutely recommend against an automatic in a 3.4 DOHC.

Take it for what it's worth. Both are good engines. You need to choose which fits the intended driving style better.

quote Originally posted by Formula88: You can do a 4.9 stick no problem. The one I drove had a 4.10 4-speed in it. Yeah, can you say LEAP off the line! Gotta be fast on the clutch, though, because those gears don't last long.

I guess I just like shifting. The 4.9/6 speed is loads of fun, but you will hit the legal speed limit before you run out of gears. This is true with most 6 speeds. When I had my 4th gen Trans Am I would typically hit the speed limit in 3rd gear and the fun was over.

I have an 88 with a 4.9 5-spd and LOVE it. It is all but a daily driver and it has plenty of power for me.
Take it to the drag strip and race it? Prob not.
Have fun driving it around town? Oh heck yeah!!!!

quote Originally posted by Formula88: .....and the 3.4 feels more at home on long twisty roads where you can stretch out each gear.

This. I miss mine.

quote Originally posted by jscott1: Maybe I'm not as experienced driving high performance race cars,

This.

The max head CFM that the 4.9 is capable of at 6,000 is 235 CFM. That's at 100% VE also. The engine is weaksauce.

One of Gm's most powerful V6's vs one of Gm's weakest V8's. It may sound like a V8, but I'd be embarrassed to tell anyone I had a 4.9 installed by choice in 2009.

I've got a 4.9.
It's a perfect cruise and stoplight-to-stoplight motor.

Regardless of what you think about the torque curve, it was designed to get a 4500 lb car down the road with a minimum of hassle.
It does the same thing in a 2700 lb car, only much more quickly.

It was also designed for reliability. Caddy owners don't like to have to mess with their cars on a regular basis.

The main thing I don't like about it is the way the 4T60E tranny shifts. When you nail the gas, it feels like it sends a telegraph from the bridge down to the engine room, calling for a downshift. After the obligatory "aye cap'n", you get your downshift. I'd imagine that the delay can be programmed out, though. (TunerCat now has software for the 4.9.)
And the waterpump... What a complete POS design. (Just MHO, of course.)

It fits in the engine bay like it was designed for it. You don't have to cut the hinge box. Or anything else. At least nothing on mine was cut.

There is really no aftermarket for the 4.9, with the exception of reground cams from Delta.


The 3.4, OTOH, likes to rev. It starts out with about the same bottom end grunt as a 3.4 pushrod, and just builds on it.
Unlike the 4.9, they can be built to produce wicked amounts of power.
IMHO, an auto tranny is a waste of a good DOHC.

Everything I've heard and read about the DOHC seems to indicate that it's a lot more persnickety about maintenance.
It requires a regular timing belt replacement. (Seems like the number was 75K, but don't quote me.)
Failure to do so can result in shredded belts and a real PITA to re-time the 4 cams.
I'm not sure if it's an interference engine or not. I've heard both stories.

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Raydar
88 4.9 Formula IMSA Fasback..........................88 3.4 coupe -soon to be something other than red

Read Nealz Nuze! Praise the Lowered!

i drive my 3.4 every day. but it is still in the car it was born in (chevy monte carlo) i like it, plenty of top end power even in the heavy monte.

if you decide to do the 3.4 remember, change the timing belt carefully ( 0 clearance engine) and before you put it in change the head gasket and intake gasket, they are prone to leaking.

quote Originally posted by Emc209i: This. The max head CFM that the 4.9 is capable of at 6,000 is 235 CFM. That's at 100% VE also. The engine is weaksauce. One of Gm's most powerful V6's vs one of Gm's weakest V8's. It may sound like a V8, but I'd be embarrassed to tell anyone I had a 4.9 installed by choice in 2009.

Whatever.

quote Originally posted by 86_fiero_gt_92: if you decide to do the 3.4 remember, change the timing belt carefully ( 0 clearance engine) and before you put it in change the head gasket and intake gasket, they are prone to leaking.

I've never heard about a leaking head or intake gasket.

What *will* leak is the O-ring from the oil pump drive. Same O-ring that leaks on the 2.8 distributor.
Problem is... I believe that you've got to remove the intake and right (rear) head to get to it.

quote Originally posted by Emc209i: One of Gm's most powerful V6's vs one of Gm's weakest V8's. It may sound like a V8, but I'd be embarrassed to tell anyone I had a 4.9 installed by choice in 2009.

Really? Not intended as a flame, folks have different driving styles. Not everyone wants a SBC or a 3800SC. I've got a 4.9 and a 3800SC, a 3.4 P/R and building a 3.4TDC. They each have their strengths and weaknesses. I don't claim to have the fastest of anything but, that's not my goal. I like Fieros that still handle well, some engine/drive train combinations take away from the handling IMO. But, to each their own. I'm not a SBC guy but, I know some folks that are and they really like their motors. So, why would anyone be embarrassed?

Ron

For transplanting a motor with such little potential when other, far more viable, 8 cylinder sources are available. Ls4 for example. I understand that the 4.9 was the only thing people had to work with years ago, but that's not the case anymore.

I think they are on par with each other, but for totally different reasons. I love my 4.9 and the engine itself, has not given me any problems even with me beating the hell out of it, it has outlasted, a center-force clutch, 2 stock clutches and 4 different trans axles, twisted a dozen motor mounts even tearing a Turbo400 poly mount due to my abuse. Yet every time, I hit the key and it runs as good as the day it was installed. The draw back to the 4.9 is it does not rev. Ya sure you can shift it at 6500 if you want, but power starts dropping rapidly at 5000rpms. I think the peak HP is at 4500rpms. Its a great motor if you want power on tap all the time. Be in top gear on the highway or simply decide to accelerate in top gear, just twitch your right foot and go.

The 3.4 TDC needs revs to make its power. It is suited for a person that wants to drive in a spirited manor and loves to stretch out there shifts to 7000rpms. I have heard from friends that have a 3.4 that it can be picky and does need more maintenance than the average engine, but thats the trade off for a high rev sports car engine. I'll never get rid of my 4.9 because I love it, but my next swap will be a 3.4TDC. People have boosted the 4.9 and made great power, but the 3.4TDC has been boosted and shown to make nearly insane power.

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85GT Soon to be 87GT,93 Eldorado 4.9, 5spd Dual O2 Custom Chip, Custom Exhaust. MSD Everything Capt Fiero --- My Over View Cadero Pics Yellow 88GT 5spd Full Poly Suspension, Lowered 1/2" in front, Corner Carver.

quote Originally posted by Emc209i: For transplanting a motor with such little potential when other, far more viable, 8 cylinder sources are available. Ls4 for example. .

I will admit to anyone that asks that there are V8s with more potential to go fast than a 4.9, but I'm hardly embarrassed. And until someone figures out how to mate an LS4 to a manual transmission it would be dead last on my list of potential engines.

Not only that some of us have other priorities in life besides building the ultimate Fiero, like sending our children to a good school or providing a good home environment for them. Dropping $10 grand or more on a motor just for bragging rights is not my priority. Someday when you grow up you might understand that.

quote Originally posted by jscott1: And until someone figures out how to mate an LS4 to a manual transmission it would be dead last on my list of potential engines.

Its been figured out. Update your list. Or don't.

quote Not only that some of us have other priorities in life besides building the ultimate Fiero, like sending our children to a good school or providing a good home environment for them. Dropping $10 grand or more on a motor just for bragging rights is not my priority. Someday when you grow up you might understand that.

Right, because you're the only one in the world with responsibilities. Makes sense. I don't think even FieroX has that much into his motor. I could be wrong though. Anyway, the 4.9 is still old, and still underpowered for what it is.

[This message has been edited by Emc209i (edited 03-15-2009).]

quote Originally posted by Emc209i: I don't think even FieroX has that much into his motor. I could be wrong though. Anyway, the 4.9 is still old, and still underpowered for what it is.

I bet FieroX would disagree with you on this one.

Show me the LS4 manual installation. I've seen some ideas mocked up but yet to see one running. In the mean time the 4.9 is good enough.

The 4.9 is what it is: a 'cheap' V8 install - sure you can do a LS4, but not anywhere's near the cost of doing the 4.9.

The 3.4 DOHC is also what it is: high reving motor that will pull to the end.

Choice: I would go with the 4.9 (and have) but for the reason mainly due to cost (especially 5 years ago when I did it). So far, maintenance has been nonexistance of this car (once I got past the initial install problems).

Do I race the car? yes. Does it suck? Sort of, it's not as fast as some stuff, but it is also not the slowest. I go for the fun, I don't care if I win or not. Besides, if that is your purpose for going to the track (to win), I seriuosly doubt that you would choose the 3.4 DOHC either.

Would I like a higher reving motor? Yes. Would I consider installing a 3.4 DOHC today? Probably, but until that day happens, I will enjoy the 4.9.

I know the 'younger' crowd would prefer the 3.4, and all the power to them, I personally don't like to wait till the higher RPMs to make power - but that is just me. It's just not cool with today's kids to not have a hi-reving motor.

Tim, if you want, bring the 'better half' the next time to the city on a decent day. Take my car out and see what see says (assuming she can drive a standard).

quote Originally posted by Emc209i: For transplanting a motor with such little potential when other, far more viable, 8 cylinder sources are available. Ls4 for example. I understand that the 4.9 was the only thing people had to work with years ago, but that's not the case anymore.

Well, all I can say is you must be one of those working with unlimited funds. I don't happen to qualify but, I have been filling out my application for some kind of Stimulus Package from Uncle Sugar. I'll be sure to put the latest LS in when I get all those big bucks. I gotta be honest here, that's a pretty elitist attitude you've got there.

I'm pretty sure just about everyone here knows that speed costs $$$ and more speed costs more $$$$. Thanks for the reminder.

Ron

[This message has been edited by blackrams (edited 03-16-2009).]

If you want a DOHC engine, you can check out http://www.chrfab.com/ for fancy N*

quote Originally posted by blackrams: I gotta be honest here, that's a pretty elitist attitude you've got there. I'm pretty sure just about everyone here knows that speed costs $$$ and more speed costs more $$$$. Thanks for the reminder. Ron

The motor is what it is, regardless of my opinion. If I come off as an ass hole, well that sucks, but I'd rather come off that way than to be conceited about the 4.9. I like being well rounded, and part of that is comparing the Fiero to the mainstream. The 2009 Honda Accord makes 271 hp off the lot. Power standards are increasing, and 200 hp just doesn't cut it for me from a 4.9 liter motor. People associate the sound of a V8 with power, hence the "wow you have a V8 in a Fiero, it must be really fast". You might be able to wow over the uninformed public for a little while longer, but you just can't deliver when its your turn to impress. The only thing the DOHC in stock form has going for it, is its ability to change the car's characteristics into an exotic nature'd sports car, which it's capable of holding a flame to said image. The 4.9 is to imitate a muscle car; fast and visceral. It doesn't match up in my opinion.

But that's just me. I'd rather be than to seem. And if you can't afford to pay to have a LS4 installed, pick up a book and start learning how to do it yourself, because the parts really aren't that expensive.

[This message has been edited by Emc209i (edited 03-17-2009).]

quote Originally posted by Emc209i: The motor is what it is, regardless of my opinion. If I come off as an ass hole, well that sucks, but I'd rather come off that way than to be conceited about the 4.9. I like being well rounded, and part of that is comparing the Fiero to the mainstream. The 2009 Honda Accord makes 271 hp off the lot. Power standards are increasing, and 200 hp just doesn't cut it for me from a 4.9 liter motor. People associate the sound of a V8 with power, hence the "wow you have a V8 in a Fiero, it must be really fast". You might be able to wow over the uninformed public for a little while longer, but you just can't deliver when its your turn to impress. The only thing the DOHC in stock form has going for it, is its ability to change the car's characteristics into an exotic nature'd sports car, which it's capable of holding a flame to said image. The 4.9 is to imitate a muscle car; fast and visceral. It doesn't match up in my opinion. But that's just me. I'd rather be than to seem. And if you can't afford to pay to have a LS4 installed, pick up a book and start learning how to do it yourself, because the parts really aren't that expensive.

OK, I guess we project the image we want folks to view us as. Have fun.

Ron

thanks for the drive offer tim , but if i did that she might put two and two together..women are kinda smart that way...lol..i will ask what fuel pump is used with the 4.9 swap ...just wondering if the 4 cyl one is sufficient or not..thanks again..tim

Fuel pump the least you want is the 85-87 V6 pump however to be on the safe side seeing as you have to change it out anyway, go for the Corvette Pump. The Corvette pump is the same one used in the 88 Fiero's from the Factory. I can dig up a part number and cross reference guide if you want. Pricing locally, for me at least, the Vette pump is actually cheaper than the 85 Fiero pump. That is assuming you are staying fuel injected. The 4.9 uses 8 x 18.5lb injectors vs the Fiero's 6, 15# injectors. Its a common swap to install the Mustang 19# injectors on the 4.9. Which for the record are the same 19# injectors people drop into Fiero's.

the donor car is an 88 coupe...so i was wondering if that 4 cly fuel pump is sufficent or not.. if not i will swap it out and the Fi is staying not gonna go carb route...maybe even grab some #19's then too....thanks dave...get back to packing...lol tim..

quote Originally posted by thismanyfieros: the donor car is an 88 coupe...so i was wondering if that 4 cly fuel pump is sufficent or not....

the 4 cyl pump is definitely not sufficient. You need at least the 6 cyl pump.

quote Originally posted by Raydar: Everything I've heard and read about the DOHC seems to indicate that it's a lot more persnickety about maintenance.... I'm not sure if it's an interference engine or not. I've heard both stories.

Maybe you've heard both stories about the DOHC being or not being an interference engine because both those stories apparently are true, but for different years of that engine:

quote The last two years in which this engine was made (96-97) they were what are known as interference engines. Interference means it's possible for the pistons and valves to hit each other if the timing belt was to break. On the older TDC engines (91-95), if the timing belt breaks, all you have is an engine that quits running but will not suffer any internal damage, as they are not interference engines.

Source: Pages 4 and 5 of the November/December 2005 issue of Fiero Focus