what would it take to get 140HP or more out of a duke while maintaining structural integrety and reliability. im kinda curious.
------------------ 1985 Pontiac Fiero 2.5 SE, 214,000 miles and still runing!!! * 6x9" speakers in the dash * * 4 corner KYB * sequential turn signals * G/A brakes on rear only * Dodge Shadow Spoiler more pics of my 85 can be found here
1987 Pontiac Fiero GT, 131,000 miles! not running.....yet!
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04:21 AM
PFF
System Bot
Kento Member
Posts: 4218 From: Beautifull Winston Salem NC Registered: Jun 2003
A LOT OF Porting the Intake Manifold, Head, and Exhaust Manifold. Cam kit from Clifford Products or even Fiero Store. Hi-flow Cat and Exhaust system. If you get max flow thru the system you should get a ton of gains. That is what I have planned for my 4cyl when I pull it. I also plan on geting the intake and exhaust Ceramic coated.
And if that did not work, put a ton of stickers on the car, should get 300-400 hp with those
------------------ **************************************** 86 SE Needs every thing but a Motor & Sunroof Seal!!! Now for Sale! $1200.00 http://home.cfl.rr.com/fierose Web Master Central Florida Fieros http://www.centralfloridafieros.com Will entertain for SIG! Photoshop Challenged. Only you can help stop Text Sig's!
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07:12 AM
cooguyfish Member
Posts: 2658 From: Hamilton, OH, USA Registered: Mar 2002
you could do the old hot rod thing and bore and stroke, i've heard about marine cranks for these engines that are super strong and take it to 3.0 ltrs. i just don't know if it would be compatable with the fiero engine. plus you have a half v-8 (a pontiac 301 if i remember right) so some small block parts will work with that engine IE rods, pistons, rocker arms (i think arms need machining to fit right)
or dennis lagrau is talking about a turbo kit for dukes, get in touch with him.
One of the problem we face with our dukes is the engine was built for economy. The bottom end is not as strong as the dukes in other vehicles. This was done to lighten the engine for economy's sake. For a performance build, I would replace every bolt in the bottom end with ARP Studs, as well as replace the head bolts with studs. While it isn't the perfect cure it will help strengthen the engine, and make it more likely to contain the 50 extra horses you increase from the stock 90 or 92 horsepower. There is a thread called the "big bad duke" by mrossum that is worth reading. He approaches or hits the mark you are shooting for. The bottom line is most power like mentioned before comes from letting the engine breathe. Then once your duke can breathe, and you have the bottom end built up, you can start spending money and adding goodies to generate more power. Of course you can stroke it if you like, by using a different crank. If you are going to the trouble of stroking it, adding a cam is almost a necessity. Occassionally you will find a hooker header available on Ebay, or even the hooker intake manifold for 86 and earlier engines. The Hooker throttle body with the huge throttle bore is still available, and while it will not fit the stock 86 and earlier intake, an adapter plate can be fabricated. At least one forum member, erikred has had good luck with a custom lightweight fly wheel and a stroker. If you are really brave you can venture into the world of turbocharging. If you keep the boost around 5 pounds you won't have to run a two stage MAP sensor, but you will need to do a custom chip and some sort of fuel managment. As you can see there are a number of ways to wring out more power from the duke, and they usually aren't cheap. To protect your work and investment you have to strengthen the block to make it all work together.
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08:45 AM
furious_fiero Member
Posts: 3028 From: Surrey,BC,CANADA Registered: Mar 2002
Has anyone ever dyno'd, 1/4 mile tested, or otherwise field tested/proven any mods to the 2.5 (outside of boost or nitrous or a SD4) that have plainly and obviously worked?
You guys are incorrect. The cheapest way to get 140HP out of a duke is JUICE Seriously run a 50 shot and you are there. That is small enough not to hurt your engine. Besides you wont be running it all the time.
stimpy: the duke is a lighter engine and it will be in a light car. the duke with 140 will beat a 2.8 with 140 due to the weight difference. besides 140 out of a duke would be more fun, both to drive and to build.
ls3mach: dude, look at how many miles are on that engine, and than tell me that! as stated in my sig below, 214,000 original, unrebuilt miles! I'm eccentric, not stupid.
------------------ 1985 Pontiac Fiero 2.5 SE, 214,000 miles and still runing!!! * 6x9" speakers in the dash * * 4 corner KYB * sequential turn signals * G/A brakes on rear only * Dodge Shadow Spoiler more pics of my 85 can be found here
1987 Pontiac Fiero GT, 131,000 miles! not running.....yet!
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04:35 AM
88Fiero2M4 Member
Posts: 349 From: Stratton Colorado United States Registered: Jul 2003
the Comp cam and the Roller Hydrolic lifters at the Fiero store are all that is needed to get it to 134 hp according to desktop dyno. I have my 86 up to about 110 to 115 range with just removing the Catylic converter ac belt and installing a K&N filter. with just those three items I noticed a big differance in launches and in acceleration. that was before I blew the engine cause the Radiator was plugged up. I found a new engine and when I get the cash for the Cam and the Lifters I will put it in with the other three items I mentioned and it should make at or above 140hp and that will keep it cheaper then most ways. Of course that is because the engine I am getting is already torn apart and ready to modify. BTW I live in a small community about 150 miles from the nearest city.... Denver so Emmisions testing isnt done here and the Catylic converter isnt required. if you live in an area that requires testing my suggestion is go to a near by county where testing isnt required and get you a P.O. Box there regester you car in that county and then you arnt required to test it.
------------------ Don Pottorff Red 88 Fiero 2M4 Silver 86 Fiero 2M4
[This message has been edited by 88Fiero2M4 (edited 11-06-2003).]
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04:42 AM
tednelson83 Member
Posts: 1993 From: Santa Clarita, California, USA Registered: Jul 2002
BTW I live in a small community about 150 miles from the nearest city.... Denver so Emmisions testing isnt done here and the Catylic converter isnt required. if you live in an area that requires testing my suggestion is go to a near by county where testing isnt required and get you a P.O. Box there regester you car in that county and then you arnt required to test it.
i live in California, testing is manditory in all parts. im also closer to the coast, so i cand register it in another state...Cat stays on.
why would just adding a cam bring it up 40 ponys? wouldnt it need more? so port/polish the intake, head, and exhaust, and add a better camshaft, and i will make over 150 horses? wow!
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06:42 AM
PFF
System Bot
GTFiero1 Member
Posts: 6508 From: Camden County NJ Registered: Sep 2001
The big bore Holley Throttle body is for the 84-86 dukes and available from the Fiero Store. The Fierostore also offers a nice looking header thats priced pretty resonably for the 4 banger also, and of course they have the lumpy camshaft. Could throw on an Ocelot exhaust from them too or something a bit better from somewhere else. All that will cost under $1,000 if you install it yourself and should get you at least 125hp but probably more, especially if you have the intake ported. Could also have the cylinder head shaved a little bit (1 thousanth should be good) to highten compression for more power, just remember to use a little bit higher octane gas
------------------ + a silver 85 2M4 and a gold 87 2M4 --Adam-- IM AOL: FieroGT5speed
stimpy: the duke is a lighter engine and it will be in a light car. the duke with 140 will beat a 2.8 with 140 due to the weight difference. besides 140 out of a duke would be more fun, both to drive and to build.
ls3mach: dude, look at how many miles are on that engine, and than tell me that! as stated in my sig below, 214,000 original, unrebuilt miles! I'm eccentric, not stupid.
I missed the mileage part. I have to say though if you are wanting to do performance parts and arent planning a rebuild, I doubt that nitrous would do anymore damage than the new parts will do.
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12:34 PM
Blue Rocket Member
Posts: 241 From: Jacksonville FL Registered: Mar 2002
Ok that sounds good. I plan on a rebuild, port and polish. Just Many of the mods you would do to get tons of power would decrease the milage you would get from the engine.
Originally posted by 88Fiero2M4: I have my 86 up to about 110 to 115 range with just removing the Catylic converter ac belt and installing a K&N filter. with just those three items I noticed a big differance in launches and in acceleration.
No way just taking off emission equiptment, ac belt, and throwing in a K&N is going to get you to 110. Maybe you got a 2-3HP gain, at best. But yu lost a few ft lbs of torque at the same time by whacking the cat.
I have heard the Big Bore Throttle body from fiero store wont work out of the box. I don't remember why exactly. I think the bore on the intake is smaller then the big bore, so its pointless. Unless you get a new intake or do work on the stock one?
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01:58 PM
Blue Rocket Member
Posts: 241 From: Jacksonville FL Registered: Mar 2002
I have heard the Big Bore Throttle body from fiero store wont work out of the box. I don't remember why exactly. I think the bore on the intake is smaller then the big bore, so its pointless. Unless you get a new intake or do work on the stock one?
You are correct. You could also cut the plasic Air box on the quater panal. There is a piece of plastic that restricts the air flow. You could try to smooth the air flow from the side of the car to into the intake.
The placemet of the air filer also slows down the air into the trottle body. The air entering the trottle body most turn 90 degress after the air filter. That would make turbulence and slow the air down entering the intake. It is not a big deal untill you improve the air flow trought the enginge.
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02:15 PM
Fiero5 Member
Posts: 8882 From: Arecibo, PR Registered: Jun 2000
why would just adding a cam bring it up 40 ponys? wouldnt it need more? so port/polish the intake, head, and exhaust, and add a better camshaft, and i will make over 150 horses? wow!
Is it just me or do any of you not know what a Cam shaft can do for an engine. take for example my Pickup wich is a Chevy with the 350 V-8, In just choosing the right Cam I can get 600 Hp out of it and that is up from the stock 210 hp. Choosing the proper cam can make a world of differance in the hp out put in a car. those honda and toyota engines have alot of cam work on them and look at what kind of power they put out stock. Besides changing the cam is a Insiders no how. proformance shops know the best on what a cam will do and my cousin worked at one in Ft. Collins here in Colorado. Go ahead and bore your engines and turbo charge them. I will go the cheaper route and buy a cam and lifters Then when My N/A tuned Fiero Blows past your Turboed one I will be the one saying I told you so. The reason a Higher lift cam will bring you more hp is cause you open the valves that much more, you alow more airflow into the cylinder thus the computer compinsates by adding more fuel. more power is the result. the same idea goes with the turbo instead it forces more air thru the smaller opening that the orignal cam opens for you. I would imagine that with port and polish and the turbo with a high lift cam and the Roller Hydrolic lifters it would not be unreasonable that 225 to 250hp could be made by the duke. That isnt a far jump to make if you have the cash but in my case I will opt for the Cam and Lifters. when I get it done I will try to get it dyno'd to satisfy the nay sayers around here.
------------------ Don Pottorff Red 88 Fiero 2M4 Silver 86 Fiero 2M4
[This message has been edited by 88Fiero2M4 (edited 11-07-2003).]
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03:16 AM
PFF
System Bot
88Fiero2M4 Member
Posts: 349 From: Stratton Colorado United States Registered: Jul 2003
No way just taking off emission equiptment, ac belt, and throwing in a K&N is going to get you to 110. Maybe you got a 2-3HP gain, at best. But yu lost a few ft lbs of torque at the same time by whacking the cat.
QUOTE]
You all seem to forget the kind of Back pressure that a Cat can cause not to mentinon that if it pluggs up it will totaly destroy an engine. By removing it you get about 10 to 20 hp gain and on a V-8 it can be as high as 50 hp. why do you think that engines in the 80's were over 100 hp less then those made just a generation before. the Catilic Converter was the major Cause in the decrease in hp. Manufactures will not tell you this because everyone out there would be removing the damn things on everything. It is a exaust flow restriction and removing it will net you a good hp increase. Fan belts cost you 5 hp each and a K&N will in come cases net up to 20 hp in a 4 cylinder I would immagine that number would be 4 to 10 hp due to both that and the Catilic converter both would unrestrict air flow in and out of the engine.
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03:24 AM
HummelHund Member
Posts: 1037 From: Niceville, FL, USA Registered: Apr 2001
Actually, it's pretty widespread knowledge that Fiero engines perform better with some backpressure. If you ditch the cat, you get some small horsepower gains in the upper rpm's, but lose quite a bit of low end torque. Plus, your car sounds like a large, flatulent bee. I know this because my 88' coupe has no cat, and exhibits all these symptoms.
------------------ 88' Fiero Coupe 2.5L, silver 5-spd.
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03:57 AM
tednelson83 Member
Posts: 1993 From: Santa Clarita, California, USA Registered: Jul 2002
Is it just me or do any of you not know what a Cam shaft can do for an engine. take for example my Pickup wich is a Chevy with the 350 V-8, In just choosing the right Cam I can get 600 Hp out of it and that is up from the stock 210 hp. Choosing the proper cam can make a world of differance in the hp out put in a car. those honda and toyota engines have alot of cam work on them and look at what kind of power they put out stock. Besides changing the cam is a Insiders no how. proformance shops know the best on what a cam will do and my cousin worked at one in Ft. Collins here in Colorado. Go ahead and bore your engines and turbo charge them. I will go the cheaper route and buy a cam and lifters Then when My N/A tuned Fiero Blows past your Turboed one I will be the one saying I told you so. The reason a Higher lift cam will bring you more hp is cause you open the valves that much more, you alow more airflow into the cylinder thus the computer compinsates by adding more fuel. more power is the result. the same idea goes with the turbo instead it forces more air thru the smaller opening that the orignal cam opens for you. I would imagine that with port and polish and the turbo with a high lift cam and the Roller Hydrolic lifters it would not be unreasonable that 225 to 250hp could be made by the duke. That isnt a far jump to make if you have the cash but in my case I will opt for the Cam and Lifters. when I get it done I will try to get it dyno'd to satisfy the nay sayers around here.
This a joke?
A camshaft has to be matched to the RPM range you want to run along with the rest of the engine... intake, exhaust flow, compression, ABILITY of rotating assembly to not explode at the rpms you want to runs at. There is no way in hell a cam change alone is going to turn a 210 hp 350 into a 600hp 350. In the 210 hp 350 with factory 8.5:1 cr or so, small port heads with small valves with stock exhaust manifolds and fuel system... stick that monster 600 hp cam in and you'll have no torque and less hp because it's most likely designed for an engine with 13.5:1 cr, a lightened valvetrain with stronger spring, super high flow heads, single plane large runner intake blah blah blah... ie a 600hp normally aspirated small block is most likely a $10,000+ engine and is going to be designed for a specific purpose like circle track or drag race.
All a cam change does is allow you to optimize valve timing events for a specific rpm range. You can play with lift, duration, overlap to optimize specific traits of an engine, you can't make a low compression, small port torque engine make massive horsepower just by changing the cam. on an older smog motor you might get a 20% gain with a more modern grind that is optimized for performance use. Remember that an engine is basically an air pump. If the cam that is in there allows the cylinder to fill at a certain RPM... leaving the valve open longer or open further isn't going to fill it any further. Leaving it open longer is going to kill vacuum and torque. Opening it further is going to require stronger springs ( to then close those valves without bouncing) a more agressive profile etc... meaning more rotating resistance. If the intake/head/exhaust is flowing it's limit, pushing the valve out further isn't going to help, you will actually lose power due to the other losses. Upgrading from a hydraulic to a roller cam will normally gain power due to the valve being opened faster by the more aggressive ramp giving more area under lift with the same or less duration. But like I said... probably no more than a 20% gain without other mods if the 'perfect' cam is chosen to match the engine and gearing.
Just hoping to clarify things a bit...
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06:13 AM
nick2x88 Member
Posts: 450 From: sacramento, CA Registered: Feb 2003
After having driven both the 2.5 (the 88 version with 92hp no less) and a 2.8 (in my formula), all i can say is that the 2.5 is more than a cam change or cat swap away from the 2.8. Fieros already come with decent cat converters, and unless it's plugged or damaged, it's probably fine. You'd have to do a lot of work with a 2.5 (the single biggest thing is the crappy stock head, and that is really where your power is hidden at) to get it to be zingy and rev happy and fun like the 2.8 (or the quad 4...) The 2.5 was just never designed to be that kind of motor, so you have to work a lot harder to get there.
The 2.5 was just never designed to be that kind of motor, so you have to work a lot harder to get there.
I agree. The 2.5 requires more work to get it up to a 2.8 level in some areas. For example, if you have a 2.8 Fiero and a 2.5 Fiero side by side, you have to drive the 2.5 hard and exact with very little room for error to "get" it to perform similar to a 2.8. This would be more driver than performance. Someone with a good 2.5 who knows how to drive it could easily outperform someone with a 2.8 who doesn't really have the experience to know how to push it properly. However, take two people in the same scenario but who are both fairly equal in driving abilities and it would be very very interesting
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11:49 AM
ThaFieroMunk Member
Posts: 945 From: Whitby, Ontario, Canada Registered: Dec 2002
The duke in a Fiero is a light weight wimp. The bottom end is very weak and the head is built for economy. The long narrow intake ports and short high exaust will not flow very well at any speed. The intake does not flow well and the exhaust is very restrictive. The super duty head will outflow the stock head by a wopping 80% right out of the box without any porting or polishing. The S/D crankshaft is fully counterbalenced and made out of forged steel not cast iron. The S/d block has about twice the iron in it. Lots more webbing. These things are essential if trying to make any horsepower and still maintain reliability.
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03:06 PM
virii01 Member
Posts: 515 From: Lincoln, NE, USA Registered: Mar 2003
Is it just me or do any of you not know what a Cam shaft can do for an engine. take for example my Pickup wich is a Chevy with the 350 V-8, In just choosing the right Cam I can get 600 Hp out of it and that is up from the stock 210 hp.
If you can prove to me that you can go from 210HP on that motor to 600HP, hell even 350HP just by changing the camshaft and nothing else, I'll print this thread and eat it. Otherwise I'm waving the BS flag for the same reasons another guy mentioned above. The camshaft does have a big effect on the engines characteristic and power, but it must be matched to the rest of the engine. If it is a high lift/duriation cam, it is going to need good fuel and air delivery as well as free flowing exhaust to move all that air, something stock components on a Chevy truck V8 aren't going to do. I don't mean to sound rude, but that is just an absurd claim.
quote
Go ahead and bore your engines and turbo charge them. I will go the cheaper route and buy a cam and lifters Then when My N/A tuned Fiero Blows past your Turboed one I will be the one saying I told you so.
Hmm, a 3.0L Duke Turbo vs. a 2.5 w/ a cam & lifter change, I'll put my money on the 3L Turbo anyday.
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03:57 PM
Philphine Member
Posts: 6136 From: louisville,ky. usa Registered: Feb 2000
if you have a local libary with back issues of hot rod magazine (or some other sourse for them) there is an article in an '85 issue (i think. could be in an 84-86 issue) where they explain how to get 140hp out of a duke. i think thats where they said the limit of reliability was. i want to say they did a 180hp build up too but it's been a while since i've seen the article.
i think the 140hp build up was done without finding anything really special, but you'd have to find the article to know for sure.
if you find some back issues remember the cover has a picture of 3 hot rodded 4cly engines (ford, chevy, pontiac) as it was the feature article for that issue.
if you have a local libary with back issues of hot rod magazine (or some other sourse for them) there is an article in an '85 issue (i think. could be in an 84-86 issue) where they explain how to get 140hp out of a duke. i think thats where they said the limit of reliability was. i want to say they did a 180hp build up too but it's been a while since i've seen the article.
i think the 140hp build up was done without finding anything really special, but you'd have to find the article to know for sure.
if you find some back issues remember the cover has a picture of 3 hot rodded 4cly engines (ford, chevy, pontiac) as it was the feature article for that issue.
I have that issue. For the 140hp build up they used a stock block with a cast iron SD head, Edelbrock intake manifold with a Holley TBI, Ultradyne camshaft, a header and a reprogrammed chip for the ECM.
Pat
[This message has been edited by T-top Fiero (edited 11-07-2003).]
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07:45 PM
dasher Member
Posts: 231 From: edmonton Canada Registered: Jan 2003
ok everyone i have been watching this for a few days now wondering if i should give my 2 cents well here it is. can a duke make 140 hp N/A yes i drive one everyday. after meny months of work me and a machinest friend found the best, cheepest and most relayable way to build a more powerful duke. we started out with a 84 no roller block i got out of my parts car. striped it down and off it went to the shop. the first step was the over bore +.0063 a bit risky. with a big iron block, me and (dave) decided that was going to be the magic number with out too much risk of blowing up. i then found a merine crank and had everything made to fit SBC robs. i had a 1 peice rear main built by fulidseal. the assembly of the short block was about 3 weeks of tinkering but it all came to gether well. Then to the head 1000 off the block and 4000 off the head for a bit better C/R. port and polish, valves triple cut, custom stiffer valve springs, and port matching was all done on the head. the Cam shaft was the big problem because i wanted a car i could drive everyday with good gas mileage but still better the stock. i looked at comp cams and found the one of my that would be the best. high pressure oil pump and some geskets where all that was left. i had the car a the local dino shop last week and pulled 141hp at 3500 rmp if i can get a scaner i'll post the slip. honestly i not that happy with the # i was hoping for much more but i guess it's not that bad. honestly i have lots of the part #'s and such if any one would like them i sure i have forgetten some stuff in the list above if i think of anything else i'll be sure to post it. lastly the machine work is something i dont understand perfectly so if i can get dave the machinest to sit explane it better to me i'll pass the info on. sorry about the delay
sorry SBC flat top pistions and rings
------------------ 86 coupe 3.0L P&P shaved, 4 cyl 5 speed full Body kit ASA Rims hood and light mods
[This message has been edited by dasher (edited 11-07-2003).]
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07:48 PM
Nov 8th, 2003
iced_theater Member
Posts: 1755 From: Green River, Wyoming, United States Registered: Jun 2003
I think I'm going to have to give this a try. All of this controversy over the "Duke" has peaked my interest. One question: If I were to track down a "Duke" from another car that was not built lightweight for economy, would the mounting holes match up with the stock Fiero mounts?
------------------ 1986 Fiero Sport Under Construction as of now
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06:30 AM
tednelson83 Member
Posts: 1993 From: Santa Clarita, California, USA Registered: Jul 2002
141 WHP at 3500 rmp red line 6200 rmp it was last week and the air temp was a bit cooler in the shop. the S-10 block has the oil filter in the wrong place at a angle up right under the alt so you have take the alt of to change the oil. and i was told that there was little difference.
------------------ 86 coupe 3.0L P&P shaved, 4 cyl 5 speed full Body kit ASA Rims hood and light mods
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01:03 PM
nick2x88 Member
Posts: 450 From: sacramento, CA Registered: Feb 2003
That's quite an impressive gain actually, you probably close to doubled the RWHP. I am curious if your HP peak was at 3500rpm. If so, it may be because the stock ECM calibration is off for your engine (it has no idea the engine can flow that much air and just is not adding enough fuel).. which is to say, there may be even more power to be found. Did the dyno people give you an air/fuel ratio graph with your dyno sheets as well?
Either way, congrats! Hope you can post that dyno sheet.
quote
Originally posted by dasher: ok everyone i have been watching this for a few days now wondering if i should give my 2 cents well here it is. can a duke make 140 hp N/A yes i drive one everyday. [...] i had the car a the local dino shop last week and pulled 141hp at 3500 rmp if i can get a scaner i'll post the slip. honestly i not that happy with the # i was hoping for much more but i guess it's not that bad.
You are using alot of simmilar parts that I plan on using. And what is your compression ratio? Did you do anything to the computer or TB?
I dont plan on going as far into the mods as you Dasher, but I do plan on changing my crank to a better one, but keep the stock stroke, using stock rods, and also using flat top SBC pistons, maybe boring the block out a bit. But I am going to use the Fiero Store's Roller cam.
Next year we can show them V6 Fiero's what a Duke can do eh Dasher?
One day I'll have another...
