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Posted:
Wed May 20, 2009 8:12 pmby bruce
Anyone here mess with the GM 2.5L Iron Duke engine?
All this car talk here on the forum has me looking at my 84 Fiero that's sitting here not running. Tractor's are getting expensive and I've been toying with the idea of selling out and dabbling in this project.
I know the Duke is not a performance engine but I just want to dabble not go racing, something for me to have some fun in and not break the bank on . . .
Posted:
Wed May 20, 2009 9:59 pmby jfholm
Posted:
Wed May 20, 2009 10:06 pmby bruce
Still have that head? ???
Was it the cross flow head?
Edited By bruce on 1242871632
Posted:
Wed May 20, 2009 10:45 pmby Malvin
Bruce I know were there is two of them fiero at if you need parts they are one mile away from my house they both have
the 2.5 four cylinders engines in them you can get them both really cheap.
Malvin 
Posted:
Wed May 20, 2009 10:48 pmby jfholm
Bruce,
I did that head for a customer who was using for drag racing. I did that in April of 1986. I have no idea where it has gone to.
Flow specs for that head at 28":
lift intake exhaust
.050" 32.5 cfm 29.3 cfm
.100" 60.1 52.8
.150 84.4 90.1
.200 109.6 108.8
.300 146.1 150.9
.400 178.6 189.1
.500 197.3 208.6
.600 213.5 218.4
.650 220.1 221.7
.700 223.3 224.1
here is pictures from a 1999 GM Performance Parts Catalog:
Posted:
Wed May 20, 2009 10:50 pmby jfholm
btw the head I did was the bottom cast iron head not the fancy aluminum cross flow one
John
Posted:
Wed May 20, 2009 10:59 pmby jfholm
Here is a picture from that catalog of the intake we used on it.
John
Posted:
Wed May 20, 2009 11:07 pmby jfholm
I recant - that manifold is NOT the one we used although we used one similar to fit the cast iron head - its ports were paired and not sperate like these.
John
Posted:
Wed May 20, 2009 11:17 pmby bruce
Thanks for the info John!
Malvin, might have to take a drive up your way.
Posted:
Thu May 21, 2009 12:25 amby coulterracn
Paul Vanderley, a reputable engine builder in Biloxi, MS was under contract with General Motors Performance division to do R&D on this engine. One of His son's drove a Pontiac Sunbird in the NASCAR sanctioned Mini-Stock class.
Paul was making good horsepower with the 2.5L engine and it lived thru the abuse.
Freddie Pendarvis, a reputable engine builder in Mobile, Al has a V6 Fiero. That car does a nice wheel stand and looks like a grocery getter. Freddie likes to paly with Turbo's, that's all I have to say about that.
Ray
Posted:
Thu May 21, 2009 12:37 amby coulterracn
John,
I have a question about the flow numbers and the ration of intake to exhaust. Would this be a good head for a turbo and what effect would the forced air have on the intake side? I've been a normally asperated guy all these 37+ years of racing. There's alot I'd like to learn about making power with a turbo or rather turbo's.
Ray
Posted:
Thu May 21, 2009 1:31 amby jfholm
Ray,
If you look at the picture of the head, the botton cast iron one you will see that the exhaust ports are just about the same size as the intake. The head probably really needed 2.02 intake valves.
In the back of my mind the connecting rods were the same size on the big end as a 350 Chevy but 6" long.
Keeping that in mind, Bruce, I have a set of 4 used SBC aluminum rods but they are only 5.7" long.
John
Posted:
Thu May 21, 2009 2:13 amby slracer
Bruce, If you want HP, a neighbor of mine makes an adapter setup to drop a Cadillac Northstar into your Fiero. 
I haven't met him but this would be a good excuse!
Doug
Posted:
Thu May 21, 2009 6:33 amby coulterracn
I remember back in the day when GM had four different performance shops doing R&D on the Little Iron Duke. A friend of mine drove a VW Beetle in the Mini-Stock class that Vanderley's son ran in. The Pontiac was fast but couldn't shake loose the VW. We were running an 1800cc air cooled engine with ported dual port heads and a Scat camshaft. I wish I would of had a way to flow the heads then.
Have you ever read articles on modifying a cylinder head and the writer said not to remove materials in certain areas and you study the head, intake and exhaust as a total package and can't understand why they made that statement?
I didn't know it at the time but I was porting the VW and small block Ford heads in such a way I was getting the swirl effect before it was a popular subject.
Sorry about that, didn't mean to keep rambling on.
Ray
Posted:
Thu May 21, 2009 6:50 amby bruce
A friend of mine dropped a 3800SC into his 88 Fiero GT and it is wicked!!
I'll have to visit the local salvageyard next week and see what he has laying around. I've given some thought to the North Star and a NA 3800 the 3800SC are a tad "rich" for my taste right now.
If I do anything it's going to be based on salvageyard parts.
Ramble away . . .
Edited By bruce on 1242903270