I know there were some people working on a belt driven supercharger for the 2.5, I am just curious, has anyone succeeded? With modest boost (say 5 lbs) it should make a pretty fat torque curve and if you observe the 4500 to 5000 rpm limit it should be able to stay together.
Any comments (no do not ask why, I would just like to know).
To be honest if I could build a 3.0L Iron Duke with a supercharger and about 180 - 200ft/lb of torque I would be happy. I don't care much about horsepower (which, given the low redline would not be that impressive anyway). I cannot afford an SD block and crank, but I have seen here that there are alternatives available as long as you don't intend to rev it too high or over boost it.
I am not fanatically devoted to the Iron Duke, I am also investigating the Caddy 4.9 and the Quad 4, I would consider a 3800 as well but the SBC is more power ( and more involved) than I am interested in. I don't want a super car but I would like enough extra punch to keep up with modern economy cars
Ira No flames please, I am just looking for suggestions.
I made a turbo kit for a duke. It was pretty neat but alot of work and mixed results. Oslo has it now.
------------------ 88 Fiero coupe 2.5 5 speed, Custom IHI RHB6 turbo equipped, gutted and track abused 88 Coupe Project "F-88" has begun....Classified TOP SECRET **your gonna love this** 88 Fiero Coupe 2.5/auto Not sure what I am going to do to this one! 87 Fiero GT 14.9/ 89mph **4.9 PFI swap in progress** 87 Fiero Coupe 91k miles 86 Fiero SE 88 Mazda RX-7 'vert SBC v8 383/T-5 Always have engines, fiero parts and accessories for sale. Custom engine swaps and chassis modifications are available.
BTW guys and gals, I have no particular attachement to the four cylinder but since it is in the majority of Fieros, and it is relatively simple to work on, wouldn't it be nice to goose it up to about 120hp, that is over 30% improvement and should not stress the engine (1.6L econobox engines make that power through high revs, a 2.5 should manage it with a 5000rpm redline).
Most of the old Pontiac V8s were low rpm machines, revving only 4500rpm but making mountains of torque, unlike the Chevys which liked to rev. The resulting performance difference between a 455 Pontiac and a 454 Chevy was not that great, the Pontiac was quicker off the mark and the Chevy had the top end power.
I don't think a car needs much power to be a sports car, it is a combination of many factors (did a post on that once but I can't find it) but a strong torquey four can make up for other shortcomings.
i'd like to bring up my favorite little engine (4 banger anyway)
the LLO. saturns engine. built along the same lines as the quad four, but using MPFI and a distributerless ignition system.
the SOHC '95-02 made 100 HP at 3000 and leveled off from there... it also gets close to 30 mpg and is very reliable. not bad for a single cam 1.9
the dohc is based on the same block but uses flat top pistons and a 16v head to produce 124 hp at 4300 rpm.
both engines are all-aluminum and weigh in the area of 200 lbs. very reliable up to about 200K where things get iffy.
parts from different years (13 years total) are interchangable. so with careful planning '94 shortblock, '95 head, '92 valves, '97 valve springs and a '92 exhaust manifold you're looking at about 135 hp.
they are availible in junkyards fairly cheap and parts are still availible. aftermarket parts are...obtainible, but not cheap.
most NA built motors produce around 170-185 hp. most reasonable turbocharged motors run 220-275. a full track motors ran 487, but we don't expect it to last too long. another company is building a 650 just to prove it can be done. they want 10 passes out of it...
plus you'd have the advantage of being the first to ever swap one.
there was a site on the web(it used to be on homestead) of an s/c'ed 2.5l; but I haven't found it again(would love to know what happened with it). Other than that I'd like to try to s/c a 2.5l at somepoint after I get my car on the road.
Well, at one time the Fiero store in conjunction with Kick Hill fiero had a running prototype for a centrifugal supercharger setup on a 2.5. The blower itself was mounted on the back of the motor and driven by a jackshaft that ran the length of the engine. This project was scrapped at some point, but I am not sure why. I know the test car ended up with a clogged cat that resulted in a fire.
In my opinion, if someone were really interested in building up a 2.5 it would be better spent money to order a super duty head from pontiac, install a big cam, and work from there. That should net some pretty solid gains, and with a full rebuild could you probably max out the performance potential of the engine block easily.
The quad four is a much better choice as far as 4 bangers go. Also if you've checked the GM performance parts catalog lately, there is EXCELLENT support for the ecotec 4 banger...just food for thought.
I agree that it takes serious modifications and lots of cash to build a powerful 2.5, that is why I am looking at options which will give a modest power gain at low rpm and not overly stress the engine.
For example, the stock crank is quite flimsy and the connecting rods are suspect, however both seem more prone to failure with excessive rpms due to balance issues (I know this is oversimplified but....). The supercharger idea just seems like a natural for an engine which needs low rpm power. Unlike a turbo, which must be carefully sized and wastegated and which adds heat to the engine compartment, a super charger which is sufficiently small can be regulated by pulley size and either waste gated at a low boost level, or a cut out using a clutch if a certain rpm or boost level is exceded. Not a simple proposition but still more suitable than a turbo for this application.
This is just my opinion based on what I know about the characteristics of both forced induction systems, I would use a turbo on a suitably strong engine which could produce lots of power and allowed high revs, I would use a belt driven supercharger in situations where the engine was limited in power potential or rpm.
Ira
[This message has been edited by Monza76 (edited 05-30-2003).]
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09:46 AM
Kris Duck Member
Posts: 193 From: Coquitlam, BC, Canada Registered: Dec 2002
The only person I know that had a belt-driver SC is Toni Ryan. I always figured he was on PFF, but in searching the archives, I can't seem to find him. Toni? You out there? Anyway, I've got his email address somewhere, he's the guy to talk to. He races his 4cyl in SCCA, it's a pretty cool little car. I've got several pics of it. The interior is full of Autometer gauges. Anyway, he was runnign (I think) an Eaton M40 from a T-bird. Last I heard it had troubles with blowing out gaskets.
it is quite easy to squeeze 200 hp out of a duke naturally aspirated, you would not need a turbo or SC. there are a couple of examples floating around on the forum.
i have personally seen a Fiero with a 2.5 bored and stroked to 3.0 that had an output of 341 hp/ 268 Torque at around 7000 rpms.
It was naturally aspirated, but it was a superduty
------------------ -Monkey
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01:38 AM
FieroMonkey Member
Posts: 3294 From: poway,CA,USA Registered: Nov 2002
oh ya, i almost forgot. the 2 main reasons the duke flys apart at 5000 rpms is the crank is balanced practicly not at all, that and the bottum end that holds in the crank is not very sturdy.
the duke has the potential for more power after 5000rpms, but those two things are what will keep you from getting to it. a turbo or supercharger wont really give you much unless you can break past the 5000rpm barrier.
to do that, snag one of the 86 s10 chevy pick up dukes. the blocks have a far stronger lower end due to the pulling requirements a truck chassis has.
after that, pick up a stronger (and balanced) crank, a mercruiser cam, and you will have the stability to do anything you want to gain the most HP over 5000rpms: bore/stroke, deck the block and heads, boost, you name it.
as so many have stated, you wont get a superformance motor from doing all this (unless you go SD4) however, in my humble opinion, the duke is the only motor the fiero ever had that was a "pontiac" only motor, and not some GM cross-over. which to me makes it more unique to modify.
might be heading off the subject here, but i wanted to say this for a while. you can go 3.1, 3.4, 3.8, 4.9, 5.7, or whatever, the fact remains that no matter how much horsepower you get from one of these, you likely wont have the fastest king of the road fiero, because there will always be someone faster.
so, in a nut shell i encourage the modifying of the duke, and tend to chuckle at the "its a waste of time, you can get more power with..." because where do you stop, its not a competition to get the most hp, because you never will
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01:50 AM
jscott1 Member
Posts: 21676 From: Houston, TX , USA Registered: Dec 2001
Can you explain your "pontiac only" comment? when you yourself point out that Chevy S10s had dukes in them? I guess you meant developed by pontiac.
I'm ready to dump my duke in my coupe because its 98 or so hp is a joke on today's roads, and the measly 25 or so MPG is not worth it. Any decent V6 can do as well mileage wise and even a V8 with the right gearing.
On the otherhand if there were bolt on performance parts I might be interested, but I doubt the gains would be worth it.
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02:31 AM
FieroMonkey Member
Posts: 3294 From: poway,CA,USA Registered: Nov 2002
the s10 duke is a chevy derived variant of the pontiac designed duke. designed, engineered, and built for pontiac, by pontiac. and i dont believe chevy started with their version until 86. the 2.8 was already a gm shared engine, that is what i meant by the 2.5 being the only "pontiac" engine offered in a fiero. you arent going to get the 200+hp i mentioned with a bolt on item.
also, the 341 hp duke fiero i saw/rode in was netting 25-35 mpg, not bad considering its hp output. i assume the good milage is attributed to a more refined tuning setup he had, plus the much higher compression ratio.
as you stated, you can get as good, and often better milage with a bigger engine. my 91 vette used to get 25mpg, and i hear the 3800 II motors get 30-35mph.
These are probably easier and more stable engine upgrades for your Fiero without question. I am just enamered of using the 4 bangers to get outrageous hp out of for fun, and for originality
P.S. i would love to snag your coupes 2.5 when you "dump it". please let me know if you decide to get rid of it and i will gladly start having some fun with it
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02:48 AM
hyperv6 Member
Posts: 6132 From: Clinton, OH, USA Registered: Mar 2003
The Duke can be built to big HP but the Super Duty parts are now hard to come by. Also HP vs $$$ is not good. I met a guy 10 years ago that did a SD engine at the tune of over 250 hp at $9,000 1990's dollars, he was glad he built it but would not do it again. How about the new ECOTEC 4 with the dealer supercharger? they are getting cheaper and are very light!
I am a little confused here, some sources say use the S10 block, others say the S10 block is no good because it does not have the side mount water pump. Does anyone know for sure, I think mrossum said he tried an S10 but the water pump problem stopped him, does anyone know if there is more than one version of this stronger block?
Ira
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11:07 AM
FieroMonkey Member
Posts: 3294 From: poway,CA,USA Registered: Nov 2002
i believe i stated that this was not a practical direction when compared to other engine upgrades. again, i said i support this because it is unique, and original. also, SD4 parts are not as rare as you think. i picked one up that has never been put together for next to nothing. They are out there, and kansas racing is not the only pace to get them. yes you can spend less money and get more HP, but you will still be one of the many many many people that have done the very same thing.
I like building up dukes because few attempt it, but then im not looking for the most practical $$$ to HP ratio for my efforts
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12:27 PM
FieroMonkey Member
Posts: 3294 From: poway,CA,USA Registered: Nov 2002
also. i think your friend spent too much for too little HP, the SD's are capable of more than 250hp at that price. if money is an issue, then consider that you can build a non sd4 duke to almost 200hp for a few dollars more than what a standard engine rebuild would cost
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12:31 PM
PFF
System Bot
hyperv6 Member
Posts: 6132 From: Clinton, OH, USA Registered: Mar 2003
When he built his Super Duty you could any find parts at the dealer, it was a while ago. Also his h/p was where he wanted it. I know the IMSA GTP lights were over 400HP. Good place to find S/D parts is Indiana, they use to use alot of them in midget racers.
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05:59 PM
FieroMonkey Member
Posts: 3294 From: poway,CA,USA Registered: Nov 2002
ya, i knew they were very popular in midgits, but didnt know there were parts in abundance in indiana, thats good to know. there are still quite a few SD4's still on the race track today. also, if you keep an eye on ebay there are SD parts occasionally for very reasonable prices
