Alright, I've got a few turbos layin around and I'm itching for boost on my '85 2M4. I'd like to do a 3800 SII swap later, but money's not there yet. Anyways, Engine Details : 128k on the clock and tranny, nice compression across the board. Ive got a IHI VJ11 turbo from my '92 Probe GT leftover from an upgrade. Now I haven't crunched the numbers yet (b/c this is all speculation ATM) but it should match up well.

Now big question - running ~8-10 psi of boost, do u reckon the internals will hold up? Next big question - is there already a "boost" or sealed intake that bolts to the TBI? Or are we talkin custom (I'm thinkin custom :P ). I'll plumb up an Intercooler in the stock batt location and add an MR2 style vent for airflow.

For fuel, I was thinking usin the stock injector (dependant on size)(anybody know the size?) and then usin a Hobbs switch and an extra injector to supply the extra fuel under boost. As well as at least a 190lph pump and a regulator.

I'm assuming the stock ecu can't compensate for boost (?). I have an extra Megasquirt EMS that I'll probably use - regardless.

Sry if this is scatterbrained - it's late and a long day :P Thanks for all your help guys - this truly is an awesome forum

-Dave

with those high miles and boost, i think you are going to lose the engine fast. Areas to be concerned with are the head gasket, the pistons collapsing or the rods coming apart. if you wre to replace these things with forged pistons beefier rods and a nice fresh head gasket you could probably use really low boost. Problem is your hp increase would be small. these dukes just dont respond well to HP.

These engines have been called HP proof by a lot of ppl here. They just weren't designed for performance.

ROFLMAO!! HAHAHA nice lmao. Seriously tho, if you dont' know much about the VJ11 it's decently tiny. It doesn't flow a whole lot at 8 psi (can't remember the cfm off the top of my head). But I did plan on replacin the head gasket and head bolts. Other than that, I'm not gonna drop that much money into it - I've read up some the Iron Duke and to mod it, like u said, jus isn't worth it. But humor me for a min Honestly, it's not that high mileage, esp for a mid 80s engine/tranny - she's been babied all her life so I'm fairly confident she'd give me a fun ride for a lil while Can anybody answer my TBI and injector question? Jus out of curiousity and Thanks again guys

[This message has been edited by Mag (edited 05-22-2007).]

I wouldnt bother replacing top end parts, bottom end is whats going to come apart. The crank is huge and weak, and the rods are LONG, neither are good for revs. Whats even worse, the 84's got defective rods, some estamates say 1 in 4, which pretty much guarentees most engines got one. Thing is, I dont know when this was, if it was early 84, late 84s into 85 or what. Odds are stacked against you on this one.

Not to mention, from what Ive found, the majority of engine fires were attributed to tossing a rod and oil spilling onto the exhaust. Now Id like to think this was primarily due to the 3qt system some idiot designed, which was remedyed by a bigger filter, but I have a feeling theres more to it than that.

Duke + performance mods = bad idea
Duke + boost = suicidal

Oh, and if you're going to do a louver mounted IC, use the drivers side, just route the air intake below it. It was much easier that way.

Thanks for the help man I might do it for shits and giggles and make a video of it blowing up roflmao We'll see

[This message has been edited by Mag (edited 05-22-2007).]

Buy all your 3800SCII stuff first and get started setting it up. Then "for kicks and grins" throw the turbo on there. At least you'll be ready at that point.

Yea that's what I was thinking - hell if I get the itch early, she's jus my fun car anyways not my DD Plus, if I decide to grow some balls and get bored, I'll tune it and see if that'll extend the longevity - if it for only a lil while lmao

[This message has been edited by Mag (edited 05-22-2007).]

The lower end being weaker than the top end is not accurate. It is a Fiero myth that has been discussed on this forum very recently actually. Out of a survey of forum members only one could actually verify that a duke crank actually broke, and he addmittedly over revved the engine before it snapped and it had a lot of miles on it. The rest were all "i knew a guy that said..." or "I heard of this one time..." fact is these engines fail because of head gaskets, pistons hotspotting in the middle, or collapsing, and rods that break. I have blown up duke motors and these three have always been the only resons for it.

https://www.fiero.nl/forum/Forum2/HTML/082729.html

The crank will hold together if you do not over rev it and dont throw huge amounts of boost at it. If you use a turbo that spools earlier at lower revs and keep the boost at no more than 8psi and dont over rev it, when it blows up (which i am certain it will) I am willing to bet money that it is not because of the bottom end.

[This message has been edited by FieroMonkey (edited 05-23-2007).]

im calling ring lands

here is what happened to a 50k mile Indy that I put a holley TB and bigger intake on. it was tuned perfectly and ran like a champ until the image at the top of this thread happened.

[This message has been edited by FieroMonkey (edited 05-23-2007).]

haha nice pushrods did the head come off alright with those bent like that?

edit, just thought my question through and realized that they probably are just leaning over.

[This message has been edited by Jrgicehc (edited 05-23-2007).]

quote Originally posted by Jrgicehc: haha nice pushrods did the head come off alright with those bent like that?

they aren't bent at all, it just looks like they are in the pic. I reused them and actually just replaced the 1 piston and rod from that cylinder with another from a similar mileage motor and have since put about 10k miles on it with no problems. oh course i switched back to the stock intake

[This message has been edited by FieroMonkey (edited 05-23-2007).]

Wow, talk about a hotspot! Thanks Monkey for giving me a good heads up And yes, this turbo will most definitely come on quite early in the rpm range - so we'll cross our fingers Thanks again for everybody's help

So the swirl port head drilled a hole in the piston. Quite the vortex.

[This message has been edited by carbon (edited 05-23-2007).]

^ LOL

I say go for it... redneck engineering is sometimes the most fun/rewarding because there's hardly any money to loose and sometimes it really works out and you always learn something new in the process.
Reminds me of a saturday project I was involved a couple of years ago. http://tejptrim.zapto.org/a...let_turbo/index.html
Took exactly one day to complete and didn't cost a dime. We even got a full tank of gas in the donor car.
The Toyota still runs strong and outruns a lot of performance cars although all the "experts" said it would blow up.

The Duke is an economy engine that was desiged after a gas crisis to get good mileage. It fulfills its intended purpose well. It's a terrible platform for a performance engineI It's far from an ideal candidate for a turbo but If you want to add just a bit more power, I would add a turbo only to a freshly built Duke , and insure that the boost is kept at 5 psi and below. Five psi is usually a safe boost level on just about all engines but on the Duke you'll also need to keep the revs below 4500 RPM and address the fueling and tuning issues. Several years back IRM sold the HiTech turbo kit for the Duke. It was never a popular option as you could swap to the V6 for about the cost of the turbo kit and get more power.
I agree with Fieromonkey that just bolting on a turbo to a high mileage Duke is asking for trouble.

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87GT 3.4 Turbo- 0-60 5.2 seconds
2006 3800SC Series III swap in progress
Engine Controls, PCM goodies,
re-programming & odd electronics stuff
" I'M ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 05-23-2007).]

I never said the crank would sheer in half, what im saying is its not a strong bottom end. I find the idea of a crank breaking highly improbable until you hit absolutely stupid numbers. What you will do is toss a rod, which is highly documented, almost to the point of being common. The crank being big heavy and poorly balanced will make it harder for the engine to adjust to RPM changes. The only place for that extra effort to be exerted is on the rods, which are already very long and poorly built. Not to metnion tearing up the bearings.

If you're going to go for it, enter into it planning to blow up the engine, because thats what in all probablitly will happen. That way you're not without transportation or out of a ton of money.

Guys, read my posts :P This is not my DD nor will I spend a ton of money on it - I'm gonna build it outta spare parts I have lying around so cost will be a minimum It's mainly jus for shits and giggles b/c I've had a boost itch lately and haven't been able to scratch it lol. It's all in good fun, and yes I do expect it to blow up so don't think I'm not

quote Originally posted by FieroMonkey: here is what happened to a 50k mile Indy that I put a holley TB and bigger intake on. it was tuned perfectly and ran like a champ until the image at the top of this thread happened.

Ohh my! I was wanting to get a Holley TB/intake and slap it on my Duke. Are those the original cast iron pistons?

quote Originally posted by AP2k: Ohh my! I was wanting to get a Holley TB/intake and slap it on my Duke. Are those the original cast iron pistons?

Yep, those are the originals. this was a babied 50k mile Indy too. Be carefull with that Holley and intake. I am sure a lot of people here have had great luck with them. As you can see from the pic I posted, I was not included in that club

Damn that's crazy FieroMonkey. You sure it was tuned correctly? Is the intake runner that corresponds to that cylinder not getting a good mixture of fuel/air - b/c it looks like it was runnin hella lean there and the others look 'alright'.

On another note, I think if I keep the A/R on the rich side, it should give me a decent cushion (or at least I'm hoping). B/c seriously, who has run a full standalone on a Duke? I haven't heard of anyone doing so. Albeit, I'm not gonna pour a ton of time into tuning it (unless it starts takin to boost decently, which is unexpected from what I gather). What can I say, I enjoy a good challenge

[This message has been edited by Mag (edited 05-23-2007).]

quote Originally posted by FieroMonkey: Yep, those are the originals. this was a babied 50k mile Indy too. Be carefull with that Holley and intake. I am sure a lot of people here have had great luck with them. As you can see from the pic I posted, I was not included in that club

I have a rebuilt duke with a kit bought from the FieroStore, so the pistons are hypereutectic. Maybe they will handle better than cast iron. But I thought it was running lean when I saw it too. Did you at least bump up the fuel pressure on the injector?

Btw, do you still have the throttle body/intake?

[This message has been edited by AP2k (edited 05-23-2007).]

quote Originally posted by FieroMonkey: The lower end being weaker than the top end is not accurate. It is a Fiero myth that has been discussed on this forum very recently actually. Out of a survey of forum members only one could actually verify that a duke crank actually broke, and he addmittedly over revved the engine before it snapped and it had a lot of miles on it. The rest were all "i knew a guy that said..." or "I heard of this one time..." fact is these engines fail because of head gaskets, pistons hotspotting in the middle, or collapsing, and rods that break. I have blown up duke motors and these three have always been the only resons for it.

The problem isn't that the crank will break - the problem is that the crank isn't stiff enough for its length. This causes the crank to vibrate under load and loads the rod and main bearings in strange off-center ways.

This is easy to see on any stock engine when you pull the pan and uncap a couple of bearings - you'll see the off-center wear patterns on the bearings. This is marginally acceptable at stock power levels and a stock Duke will last a long time despite the uneven wear.

When you try to push more power through that crank the vibrations get severe - and tear up the bearings in very short order. As the bearings get pounded out, the oil pressure drops - the usual end result is a broken rod sticking through the side of the block.

quote Originally posted by FieroMonkey: with those high miles and boost, i think you are going to lose the engine fast. Areas to be concerned with are the head gasket, the pistons collapsing or the rods coming apart. if you wre to replace these things with forged pistons beefier rods and a nice fresh head gasket you could probably use really low boost. Problem is your hp increase would be small. these dukes just dont respond well to HP. These engines have been called HP proof by a lot of ppl here. They just weren't designed for performance.

I dont anything about the duke, but I read the same about the 2.8 - 3.4 PR engines not being hot-rod-able only to find out it was because they had a bad intake design. Ar e all dukes carbed? Did any come with port injection like the V6s? Being an inline 4, it would not take much to make a port injection intake for them or headers etc. Just wondering. How do you think the bottomend can hold too?

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[IMG]



Trueleo.com/fiero.htm
RSpiderII@aol.com

Dukes are not carbed, they have a throttle body injection assembly.

Jim

quote Originally posted by AP2k: Ohh my! I was wanting to get a Holley TB/intake and slap it on my Duke. Are those the original cast iron pistons?

That cylinder had to be starved for gas and running super lean to blow a hole in that piston (as it shows the efects of severe detonation) or mechanical failure just caused by a defective casting w. porosity. Replace with Hypereutectic pistons and I'll bet that they last. Aslo when you rebuild scan the ECM to see what the O2 sensor voltage is . It should be around .45-.55 V cruising and .85- .95 V at WOT. Much lower O2 voltage readings siganl problems and show a severe lean condition.

quote Originally posted by Dennis LaGrua: That cylinder had to be starved for gas and running super lean to blow a hole in that piston (as it shows the efects of severe detonation) or mechanical failure just caused by a defective casting w. porosity. Replace with Hypereutectic pistons and I'll bet that they last. Aslo when you rebuild scan the ECM to see what the O2 sensor voltage is . It should be around .45-.55 V cruising and .85- .95 V at WOT. Much lower O2 voltage readings siganl problems and show a severe lean condition.

because the other 3 looked absolutely perfect, and all 4 cylinders get the same amount of air/fuel because the mixture is made at the TB and then distributed iside the intake, I am in agreement that it was a mechanical failure in the casting. There was not a spec of hot spotting on any of the other 3. But I still believe that these duke pistons are ginger and tempermental when the elements change, as they did on mine. As far as upping the fuel pressure after adding the holley, i was told by many gurus that it was not needed with the holley aftermarket TB made for this motor.

3 pristine pistons, and one with a hole.... Hmmmm... Just like on the 84's, the rods were made of different batches and so were the pistons. Metal is alot like food in that aspect. One chef will use ONLY the best, and one will use what ever is cheapest and add fillers. Problem is, BOTH chefs work on the SAME product, the food tastes OK, but which end will you pay the price later?

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carpe diem

PLEASE do it i like your thinking

document EVERYTHING.

and ill be watching

please please if and when it goes boooom have a cam ready

good luck and well it will be fun

you have montana thinking

You know I"ll have a cam running FieroMonkey, Since the fuel is injected at the TB - I think it's much more plausible that fuel jus wasn't getting to that cylinder as well as the others. I can't remember the runner design atm. But in modern day port injection systems, usually (key word) there's always a runner that gets less air or more air than other runners. On a stock power level and DD'in it, that's not a problem but when pushed, it becomes a weakness straight off. Which is one big reason everybody stopped using TBI systems. I'd bout guarentee those first three cylinders were gobblin all the fuel/air, leavin cylinder 4 w/ zip. I hate TBI setups :P And I jus woke up and ramblin so excuse me lol

But frankenfiero does have a point - and that's a very good possibility as well.

[This message has been edited by Mag (edited 05-24-2007).]

If you keep the revs down except to occasionally floor it this could last some time the duke will not handle high rpm,the turbo dukes of the 80s and 90s cured most people of trying a turbo in the duke,this is a great economy engine in the 88.mine has been slightly modified,now has the stock head and has good performance and is smooth for a duke if only I can make it run right 100% of the time,,I have seen a duke with a broken crank I was not into fieros at the time I was at a junk yard in the early 90s and was supprised at the number of fieros there,the guy behind the counter said most of them had some sort of bottom end problem,,normally the rods go before any other bottom end part.. Gm knew about the bad rods that were going in the fieros but decided it was easier to put off customers complaints than fix the problem Gm built some real trash in the 70s and 80s i hate the japs but they caused G.M to improve quality the people who build the cars did not seem to give a feces about quality ford was not as bad as G.M but they tried desparately to equals G>M>s record i ran a harley davidson franchise from 72 till 75 and the workers at the harley davidson factory actually sabotaged the bikes so what could you expect from an auto worker

Any one know about the s-10 block, i want more information and all i can find is when people are putting it in the car. And will this be better if he or i want to turbo using small boost.

I am currently working on a 85 S-10 motor for my fiero. The castings on the bottom end are a little better, but visably beefier. It has no water pump port on the side however, it mounts where the block off plate is on the fiero motor. The 85 is drilled and tapped for a starter on both sides though. All in all the same motor, except for the water pump and that it is built heavy duty for a truck...

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carpe diem

So what are you doing with the water pump port?

I am goint to use the S-10 pump and re-plumb down the motor and along the cradle to the existing coolant tube. I cannot find anyone who has done this swap yet, so I am treading on experimental ground. That was my dis-claimer...

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carpe diem

has any that has considered putting a turbo on a duke thought about putting a girdle and main cap reinforcement on the bottom end to take away some of the stress everyone says is the cause of crank failures?