on the 1987 coupes, did they change from "2m4" to "TECH4"?

Technically all 4 cylinder Fieros are 2M4's, but they dropped this designator by '87 (I think '86 coupes were the last to have this on the decklid).

The 2.5 4-cyl. engine is commonly called the iron duke......in '86 they started putting "Tech 4" on the air cleaner housing, but it was just a name GM decided to give the engine......this change has nothing to do with the 2M4 name though.

Funny, my 84 had a tech 4 sticker on the air cleaner...

I think they started calling the Dukes "Tech 4 " engines in 1982 when they went from carb to computer controlled TBI.. ( Computer = Tech ).. It made good marketing hype

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1988 Fiero Coupe 2.5L
1990 Trans Am GTA 5.7L

My 84' buick cheesebox had tech4 on the air cleaner

Oh well......I've only owned a couple of 4 bangers, so what do I know?

I can tell you it's just a name....a marketing gimmick, if you will. I guess "Tech 4" just sounded good to teh GM guys back in the 80's.

the name doesnt matter. it is still really really slow. moreover, my dad says that his '81 skylark with the carb had more power than the '82 century with f.i. and vacuum pump. and more than the '84 celebrity w/o vacuum pump. so who knows?

pil

84 - 86 are the Iron Duke

87-88 are the Tech 4. Tech 4 means they went to a DIS ignition system, different internals, etc etc etc... The Tech 4 is NOT an Iron Duke.

If your 84 says Tech 4 on it, someone used an 87-88 air filter lid.

-Karl

quote Originally posted by FieroJones: 84 - 86 are the Iron Duke 87-88 are the Tech 4. Tech 4 means they went to a DIS ignition system, different internals, etc etc etc... The Tech 4 is NOT an Iron Duke. If your 84 says Tech 4 on it, someone used an 87-88 air filter lid. -Karl

I must say that is wrong. Sorry to seem that way, but my best friend's dad was a GM Pontiac mechanic for God only knows how many years and the Iron Duke's were renamed around 1982 because they had minor revisions and the introduction of EFI to them. My car is a 1984 SE and it has a Tech IV...And it is stock, I promise you! So why do ppl keep saying to put Mercruiser cranks and Duke perf. parts on Tech IV's if they are not the same? I would recheck your information if I were you....Good day...

If you've got an oil filter inside the oil pan and no distributor, you've got a Tech 4. I think the blocks are similar, but certainly not the same. The Tech 4 has no distributor and has a hole in the block for a crank position sensor where the DIS box is located. I don't know when they came out, I know my 89 Olds Calais had it.

Is a Tech 4 an Iron Duke? I dunno, I-4 iron block, some differences...

quote Originally posted by mrfiero: Technically all 4 cylinder Fieros are 2M4's, but they dropped this designator by '87 (I think '86 coupes were the last to have this on the decklid). The 2.5 4-cyl. engine is commonly called the iron duke......in '86 they started putting "Tech 4" on the air cleaner housing, but it was just a name GM decided to give the engine......this change has nothing to do with the 2M4 name though.

This is very correct!

quote Originally posted by Poncho Jim: I think they started calling the Dukes "Tech 4 " engines in 1982 when they went from carb to computer controlled TBI.. ( Computer = Tech ).. It made good marketing hype

This to is a true statement.

quote Originally posted by FieroJones: 84 - 86 are the Iron Duke 87-88 are the Tech 4. Tech 4 means they went to a DIS ignition system, different internals, etc etc etc... The Tech 4 is NOT an Iron Duke. If your 84 says Tech 4 on it, someone used an 87-88 air filter lid. -Karl

This, on the other hand, is not correct. Just because the engine doesn't have a distriubtor? Please. . . . I bet the 87 & 88 engines (4 cylinders only) are the same too Right?
Wrong again! The 88's have the internal oil pump and filter and some of the late runs for the 87 do as well. The 87's that do not have to internal filter are still DIS systems.

quote Originally posted by John Boelte: If you've got an oil filter inside the oil pan and no distributor, you've got a Tech 4. I think the blocks are similar, but certainly not the same. The Tech 4 has no distributor and has a hole in the block for a crank position sensor where the DIS box is located. I don't know when they came out, I know my 89 Olds Calais had it. Is a Tech 4 an Iron Duke? I dunno, I-4 iron block, some differences...

This is not a true statement either. If the info given above is included to go back to 82 2.5's, the are ALL Iron Dukes as well as Tech 4s. The 2M4 is (was) just a decal that goes (went) on the deck lid and was discontinued as a sticker for new Fieros in 86 (last year for the sticker).

Maybe they should have called the distributor-less 4 cylinder cars Dis-4-Less or something? That would have killed this conversation in a heartbeat!

OH, I have four cylinder cars from all years except 85. They're all stock, all have iron dukes and all are Tech 4s. (at least one of each year) I will also add that I don't wish to have an 85 coupe either.

Maybe we need to define exactly what a Tech 4 is? When it was introduced?

I KNOW my '89 Olds Calais (not a Fiero) had a Tech 4, DIS, Internal oil filter with oil pump driven vibratioin balancer, serpentime belt,etc. I can say my '84 Iron Duke is a different block in that it has a distributor and no Tech 4 badges.

I disagree with Induiana Resto Guy. There is a difference as stated before. The Tech 4 has DIS, internal oil filter, crank driven balancer, serpentine belt. If you don't have all of those items, you don't have a Tech 4. Easiest way to tell, look for a distributor and an oiul filter outside the block, if they're there, you don't have a Tech 4.

Best regards,

John

Read the Pontiac Fiero Haynes Manual, it says what I say as well. And so does the dealer manual by Helm and so do a master machanic for Pontiac. Yes the newer Tech IV's had a filter in the pan from what I read, but that's called a revision of the original Tech IV which had the oil filter on the outside and was so renamed because it had EFI. Originally when introduced it was the Iron Duke. Around 1982 it was revised in certain areas and EFI added to become the Tech IV. Thank you much. I'll add a link to prove myself right when I can find it..

So the DIS, internal oil filter, crank balancer, and serpentine belt would be upgrades to the Tech 4 lineage? I'd buy that.

Any idea when these upgrades were introduced?

Well I can say on the Fiero's that DIS was introduced in 1987. There is a 1987 Fiero SE in my local junkyard with DIS and the serp belts. Just like in 1986 they introduced roller lifters. And either 1986 or '87 they introduced a different TBI unit from Holley; I'm 95% sure of that one. GM has done all sorts of stuff to their engines over the years. Hopefully, GM will e-mail me back. And if I stand corrected then so be it, however I doubt a dealer manual would be wrong. Then again, ya never know I'll keep ya posted on what I find out...

quote Originally posted by John Boelte: So the DIS, internal oil filter, crank balancer, and serpentine belt would be upgrades to the Tech 4 lineage? I'd buy that. Any idea when these upgrades were introduced?

The internal filter has nothing to do with the engine being a 'duke' or a 'tech 4' .. 87's had the DIS i4 and an external filter.

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Ray · Email Me! · Fierosite.com · Fiero Chat! · Project White Phantom

quote Originally posted by White88cpe: The internal filter has nothing to do with the engine being a 'duke' or a 'tech 4' .. 87's had the DIS i4 and an external filter.

I hope I don't throw a monkey wrench into the works here, but....My 1987 Pontiac Grand Am with the 2.5 Tech 4, had the internal oil filter AND DIS ignition...

2M4 = 2 Seat, Mid-Engine, 4 Cylinder
2M6 = 2 Seat, Mid-Engine, 6 Cylinder

2M4 or 2M6 had nothing to do with the type of engine in it,.. just how many cylinders.

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'85 SE - '86 Fastback SE - '99 Chevy K-1500 Z-71 - '00 HD 1200XL Sportster

quote Originally posted by kyote: 2M4 or 2M6 had nothing to do with the type of engine in it,.. just how many cylinders.

Technically it does. 2M4 = Tech IV 2M6 = 2.8 V6 It does have something to do with the type of engine it has.

all i can say is my old 84 SE did NOT have the "Tech 4" on the air cleaner. I was also under the impression that the "Tech 4" was introduced in 86 as my 86 SE (4cyl) DID have the sticker on teh air cleaner...but that's just my $.02

Fieroman

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quote FieroJones 84 - 86 are the Iron Duke

I have an 86 2M4 w/ a 2.5L Tech IV label on the stock air cleaner.

The impression that I have been givin in the 3 years that I have owned fieros was that all Fiero engines aside from the quad 4 and the 6 cylindars were Iron duke motors.

I was also under the impression that the tech 4 labeled airboxs were introduced in the 1986 fiero.

This is mostly hearsay but i've never seen a stock airbox on a 84 or 85 fiero say tech 4.

Now although my 84 had Tech IV on the cover (could have been swapped in I guess), This one does not. This is the air filter cover from an Indy:

I really dont know the answer to the question, just thought I would comment.

My 84 does not have Tech 4 on the cover, my 88 does. The 84 sales brochure does not use the phrase in describing "..a mid-mounted 2.5 litre 4-cylinder engine with "electronic fuel injection." The engines pictured have no emblems on the air filter assembly. The 85 brochure says "...an improved 2.5 litre 4-cylinder engine powers Fiero for '85." The 86 brochure says "Fiero is powered by a spirited 2.5 litre 4 cylinder engine-the famed "Tech IV."." I'm not sure how something can be "famed" unless it has been in use, so I would suppose that the engine had the name in another GM application in 85 or perhaps even 84.

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Notchbacks Rule
84 Coupe(project car)
85GT(show car)
86???(looking)
87SE (daily driver)
88Coupe (daily driver)

quote Originally posted by Fierobruiser: [B I'm not sure how something can be "famed" unless it has been in use, so I would suppose that the engine had the name in another GM application in 85 or perhaps even 84. [/B]

Good point!! And I still haven't got an e-mail back from GM yet. Maybe they thought it was a stupid question??

They probably laid off the Pontiac historian after the 75th Anniversary "celebration". They won't need another until the 100th unless Buick and Pontiac are gone by then too and it's only Chevy. Then the name will officially be changed to Generally Mediocre.

[This message has been edited by Fierobruiser (edited 09-04-2002).]

HaHa, must say that it wouldn't surprise me, lol....

quote Originally posted by kyote: I hope I don't throw a monkey wrench into the works here, but....My 1987 Pontiac Grand Am with the 2.5 Tech 4, had the internal oil filter AND DIS ignition... 2M4 = 2 Seat, Mid-Engine, 4 Cylinder 2M6 = 2 Seat, Mid-Engine, 6 Cylinder

I'll give ya, some 87 2.5 Fieros had the internal filter style engine, but for the most part the fiero 2.5 was externally balanced engine. My brothers 87 coupe had a internally balanced engine, my 87 coupe had a externally. my 88 has a externally balanced engine(but its from my 87 coupe).

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Ray · Email Me! · Fierosite.com · Fiero Chat! · Project White Phantom

Gearjammer, you mentioned putting in a Mercruiser crank. Is that something that can be done to these 4cyl's? I have a 88, and if it goes and I rebuild it, I want to build it to last a long time. Is the Merc crank stronger?

Well from what I read on this site, the Mercruiser cranks are great for stroking the engine up to 3.0 liters and they are stronger I'm sure for the marine use. You could also get a crankshaft from I believe a 70's model Nova with the 153CI Duke and that will put you around 2.7liters. Anyone got any suggestion here? I'm still a bit rusty on the older Duke mods. Oh and by the way, got that e-mail back from GM today. They didn't tell me sh*t! All they told me was the engine in the Fiero's was "a 2.5 liter electronically controlled engine with TBI" and that "some of the newer Fiero's started with the oil filter in the pan." So I guess we could all agree that they are the baseline engines and could use more power, heh..

Solotwo, good luck and we are here to help ya out if/when possible!

While researching something else, I came across the first Tech IV mention I could find in the "Fiero Press Guide". From the 1985 Fiero long-lead press release kit dated 10/22/84; "Fuel economy estimates for the standard 2.5 liter "Tech IV" with a new 5-speed manual transmission are 25 mpg city and 35 mpg highway."
Gary Witzenburg's book says, "The standard 2.5-liter Four, now called the 'Tech IV' engine by GM, averaged 25-35 mpg EPA with it's new roller lifters and the Isuzu 5-speed."
So if it's got roller lifters, then it's officially a Tech IV.

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Notchbacks Rule
84 Coupe(project car)
85GT(show car)
86???(looking)
87SE Gold(daily driver to be)
87SE Silver(daily driver)
88Coupe (daily driver)

These motors were used in several GM vehicles. Including S-10 Pickups and S-10 Blazers.

All the cast iron L4's became DIS motors and ran serpent belt for the 87 model year. This includes all the VIN R U and E engines. (The truck version is VIN E, I'm not 100% sure Vin E got the serpent but it definately got DIS. It also got an ECM controlled EGR that was not used in the cars.)

For the 88 model year, many of the R and U VIN L4's added the crank driven vibration damper. Some VIN R and U 87's may also have the damper but most I've seen don't. (Some 87's may have gotten the damper motor as a result of an engine change.)

Tech 4/IV is primarily a marketing thing. It's the same as using Fireball or Power Stroke.

For 87-88 the Tech4 decal is on the air cleaner neck of every one I've seen. The aircleaner from a DIS motor's 700 series TBI does NOT fit on the older 300 series TBI unit.

The 2M4/6 is descriptive. 2 Wheel drive Mid engine 4/6 cyl.

The trunk sticker was most likely altered simply to cut cost. It costs more to have two different stickers and apply them correctly. If a car maker can save a nickle, they usually will.

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11-Sept-01, The day the world as we knew it ended.

[This message has been edited by theogre (edited 09-14-2002).]