Hello everybody,
I know that GM put 2.5 liter 4 cylinders in the f-body's. My question is can I put performance 301 Pontiac or 350 Chevy parts in the 2.5? They are the same bore as both. But rod length and stroke is only the same on the 301 Pontiac. The reason I ask is I want to built a 4 cylinder stock car for the 4 cylinder class. So if I can swipe some performance parts off a V-8 that would be great.
Thanks for all your help, Garrett

 

From what I understand, you cant. Even though there are many similarities, the parts are way different. Another thing to worry about is the block. They are not that great. The next thing to worry about is the rotating assembly. These are very cheap, that means very weak. With that being said, you can build an "Iron Duke" to work around 150hp. Anymore than that and motor will start coming apart. The only reason I know is because I was looking at adding power to my Fiero and ran into the same problems. Check the web, the info is there.

Good luck.

 

No you can't, though you can swap parts from SBC to SBC.

 

Exactly! Even the factory LXX engines for the 50 or so Indy pace cars made only 145 HP. That's about the limit of the skinny rotating assembly. I had my '84 P-car at about 140HP with a cam, valves, and head work. It was pretty fun for a roller skate, but still limited.

I am finally Fiero-free! (Yes, the last one is GONE!) Like a lingering case of athlete's foot, I finally beat the "disease" after haveing three of them.

As for the 4-holer in the F car, even at maximum safe output, the 151 will never provide adequate torque to move the heavier vehicle satisfactorily. The beauty is that a four cylinder F car is a great start for a conversion, since the floor pan and body would have never been flexed heavily from torque and should still be in solid condition. Few of them had air conditioning, so that's one more plus for conversion. Run the "Duke" until it smokes like a Mitsubishi, while you build a replacement SBC.

 

Just FYI,

Not to be import guy here, but my daily driver 95 Talon (TSI AWD) doesn't smoke...although it only has 63K on it. Is there a magic # for the smoke Vader?

 

Oh yeah and PLEASE don't build up the 4 banger...unless you turbo it Which doesn't sound good for that engine....

 

Oh geez; not more "turbo it!" messages! We see those all the time on the V6 forum... those, and the "I want NOS!" messages. But I think it'd be kinda fun to throw some parts at the 4 cyl, why the hell not! If it's a manual tranny'd car, it probably has the 3.73/open/drum rear axle, which is the same exact strength as the V8 axles of those years (before the move for all axleshafts in '89 to a 28 spline shaft).

 

I only suggest it cause I like the Turbo Talon...but seriously, don't mod the 4 banger...they won't produce enough power to make it worth the effort/cost. Build a 406 instead

The Iron Duke should just go away forever...bad idea and bad outcome for the most part...after all the Pontiac 301 is just two Iron Dukes...and look what that gave us...tragic....

 

Yes I know how much power a 406 has, I built one for my Camaro which I sold (didn't put subframe connectors in the car and twisted it, in about a month). But I can't run a 406 in the 4 cylinder class. So I'm not sure what i'm going to use. Car has to be older than '92 not fuel injection, turbo's, superchargers, or rotory engines. So I'm not sure what I'm going to use.
But thanks for your help with this, Garrett
406's but mine could only handle about 5500 rpm's

 

I can understand your dilemna...how about the GM cylinder head that rocks for the 2.5L....I could swear that they used them for racing...with different blocks, etc. Look in the GM catalog...that could be your only option, to build a race-type four cyl...but i am sure that none of the stock parts would be of use to you.

Just out of curiousity, what kind of 406 specs do you have? I am always curious as to other 406 builds and power output. I hear you on the subframe connector issue...that is why I put mine on BEFORE the swap...

Some guy around my hometown put a built high HP 350 in a 2nd gen and tweaked the unibody pretty bad...this happened over 10 years ago and I didn't forget the lesson...

 

I thought I remember some guy that built up an Iron Duke in his Camaro, and turned it into a barely decent performer.
It's just a dim memory (I can't remember what specifically was done), but I remember hearing a .wav file of it. Sounded, um, well, crappy but healthy. Not much like a Honda with a fart-pipe, tho, which was good.

 

Ok here is the majority of the stuff I had done to it. I had originally built the engine for my 4 wheel drive pick-up but wound up putting in the car.

- Flat-top Hyperutechtic pistons 8.5 to 1
- Head milled .020, Block .010
- 3 angle valve job
- Stainless valve
- .030 pistons
- X rods, ARP bolts
- crank turned .010 .010
- engine line bored
- R.V. cam (3 steps over stock)
- Rhode lifter
- Final Compressions 9.6 to 1
- 63cc heads
- True Roller Timing Chain
- Edelbrock valve covers
- Edelbrock Aluminum Intake
- Holley 750cfm doulbe pumper carb.

Engine had about 393 horse and an amazing 456 torque (truck motor). Check it out in Reader's Rides. car ran 13.6 in the 1/4

 

Hey Vader,

A little off the topic but relative. How long will these Iron Dukes/Tech 4 engines last. I have 152,000 rounds on my 86. It runs strong but has a TON of blow-by that kind of started over night.

I bypassed the fresh air intake by cutting a hole in the air cleaner assembly to let all the blow by escape. This way I don't have to buy a new air filter every 500 feet. Its ghetto but functional.

I've checked the PCV and it seems good. Any suugestions other that rebuild??

 

Oh yea I built the engine myself for $1797 for everything. Sure the carb. and intake where used but big deal. I had an awesome engine that can beat crate engines for less $.

 

Holy Crap! It took me a while to clue in that you were talking about a 406, and not the iron duke! I was about to fill an entire page with: . Haha!
Sounds like a nice combo.

 

OK a 2.5 liter with 393 horse and 456 torque. I think that's a challage and I'm going to do it. I'm sure it could be done with 13.9:1 compression, a turbo, and a lot of nitrous (a whole lot). And it would last at least once down the strip. Thank G0D I have Cubic inches and cubic centimeters on my side.
Later

 

Actually there was an article done back in the late 80's on the Iron Duke. With performance parts, the 2.5 put out 250 ponies. With a shot of nitrous, it pushed 350...and did it reliably. The only problem doing that today is that all of the parts would run you about $10k. Would be fun in a little car though

 

great 406 buildup...what heads?

Also, i take it that you had the engine dynoed for your power #?

Thanks...

 

13.9:1 compression wouldn't work very well with a turbo.

You're car only ran a 13.7 in the 1/4? What were the 60' times?

 

Check on the tech board of Fiero.nl, there is a guy that has done a lot of work on the Duke in his Fiero.

 

Sorry about taking so long to reply about my heads. But to tell you the truth I don't know for sure. I built my motor at a friends shop and he got all the parts for me. I'm pretty sure they were stock heads just that they where milled .010.
Yes the power #'s are dyno #'s.

 

Those are great numbers for stock heads...I have to take my car to the track this summer and get #'s with stock 1970 heads and a stock TPI...gotta have a baseline before I swap on the SR...

 

Oh yea, I also had my brother Port and Polish the heads, Forgot to mention that. So that's a little extra help with flow.