I'm pretty sure Fierosound is talking about the 60 degree V6 family. The 3300 is a 90 degree V6, derived from the 3800. So it doesn't factor into this discussion.

[This message has been edited by Blacktree (edited 04-03-2013).]

quote Originally posted by fierosound: Then it was a 3100 which denotes aluminum heads. Probably had 3100 on top of the intake. In general, GM used 3.1 and 3.4 to describe iron head engines. In 1992 engine designations changed to 3100 etc. to signify the aluminum heads. So in 1992 Chev APV VAN had a 3.1 with iron heads. (only vehicle to have this) While all their 1992 cars (with 3.1L displacement engines) had the "3100 engine" with aluminum heads. Also why you see that Camaro/Firebird had 3.4L engines, while Grand Am had 3400 engines (still 3.4L displacement). Engine family tree. http://60degreev6.com/conte...DegreeV6-Family-Tree

Gen 2 aluminum head motor 3.1's are called 3.1's. Gen3 when they introduced the roller cam is when they were called 3X00 motors...
Gen1 is iron heads.

[This message has been edited by lou_dias (edited 04-03-2013).]

quote Originally posted by Gambit: <snip> Whats that big black plug coming out of the engine block, in the black painted area. I have that thing to? <snip>

I think you are looking at the knock sensor (big one on top) and the small one underneath is the crank position sensor. On my '95 3.4L oil pan there is also an oil level sensor in the side of the oil pan. Also, on the oil filter side, there are only 3 bolt holes for the engine mount. The 2.8L block has 4 bolt holes.

quote Originally posted by lou_dias: Gen 2 aluminum head motor 3.1's are called 3.1's. Gen3 when they introduced the roller cam is when they were called 3X00 motors... Gen1 is iron heads.

So what do you think Gambit has? A Gen 1 3.1? That's what I think it is because of the iron heads.

The "T" type is the LHO. 3.1 litre.

Well guys, finally got down to the cylinders. Here is a pic. What kind of engine is it? The diameter of the gap is 89 mm and stroke 84 mm. The pistons look hollow at the top? If its a 3.1 can i bore it out to a 3.4? Is this than the same as a 3.4pr with same horsepower and torque?

[This message has been edited by Gambit (edited 04-09-2013).]

Those are the dimensions of the Gen 2 Aluminum head block....
From Wiki:

The second generation, still 2.8 liters, was introduced in 1987. It used aluminum heads with splayed valves and an aluminum front cover. It was produced exclusively for transverse, front-wheel drive use.

The next year, Chevrolet introduced a full-production long-stroke 3.1 L (3136 cc, 191 CID) version in the Pontiac 6000 STE AWD, thanks to an 89 mm (3.5 in) bore and 84 mm (3.3 in) stroke. It was produced until 1994 (1996 for Mexican market) and was exported in some models.

[This message has been edited by Gall757 (edited 04-09-2013).]

It's a 3.1. Any 3.4 would have a 92mm bore.

So it looks like it is an older (91-92?) f-body engine, OR a mini van engine (Chevy lumina APV, Olds Silouhette, Pontiac Transport). The difference between them will be the obvious drilling of the starter pad on both sides (if it's from an F-body). Those pistons look like they are from an aluminum headed engine, which would yield practically no compression at all (like 7:1?) if used with the iron heads, as pictured... If that were the case, it would be quite a poor performer! But let's check the dish before we jump to that conclusion.

Check this: The dish on the aluminum headed engines pistons are 6.7mm. The F-Body/mini van pistons have a 2.6mm deep dish. That should set you straight.

Edit, No. you shouldn't bore the engine out to 92mm, that would go past where the block is safely bored. Possible, yes, but don't, it's too far. Stay with .030"-060" or about 90-91mm.

[This message has been edited by Fierobsessed (edited 04-09-2013).]

Ok, i will measure that tommorow, its midnight now here. The engine ran fine, no problems but due to the fact the 1 and 2 gear where broken i never had the change to floor it. But hearing you speak it doesn't look good. There are no holes for the starter on the other side, has a big 'T' stamped on the blok, has a knock sensor. Thats bassicaly what i know. Your help is really appreciated guys.

[This message has been edited by Gambit (edited 04-09-2013).]

It's definitely a 3.1 liter engine. Since it has no starter mount on the right side, it has to be a FWD engine. So it's probably a minivan engine. Because the 3.1 used in cars has aluminum heads and a different intake manifold.

I would advise against boring the cylinders to 92mm, because that will leave the cylinder walls very thin.

quote Originally posted by 2fiero2: The "T" type is the LHO. 3.1 litre.

Looks like that is it.

It can be bored to 92mm but why bother? If you are just rebuilding, do the minimum required to get smooth cylinder walls. For your new pistons, just try to get flat topped ones and the compression ratio increase will make up for having less displacement than the 3.4 ... you'll also have to do a lot of mods to your intake and throttle body to take full advantage of a 3.4L demand...and exhaust work...

There are no flat-top pistons available for the 3.1 V6. They would have to be custom made.

This is getting better and better. I will not bore it out myself but will have this done. I will look later on for the measurements of the pistons.
Next question. I have a vortech v1 supercharger, bought a truleo intake here from PSI. I want tot buy the 260 H Cam, 1:6 rockers, new stainless pushrods and performance springs. I will buy at fierostore because it hard for me to look it up at summit or other. I will save for the 3 inch long tube header from Westcoastfieros. Am i forgetting something or? My running ECM is the 7170. Do i need to switch?

Just contact Ross pistons and say you need custom pistons, flat top, 1.464" compression height, 0.905" pin diameter and specify your bore diameter...

So I just want to understand this, and maybe so does Gambit. Did somebody put Fiero 2.8 iron heads on top of the 3.1 block? The engine must have been not very happy considering those dished pistons.

3.1 and 3.4 pistons have a smaller dish than 3X00 pistons to maintain the same compression ratio without machining the heads for more volume.
The iron head combustion chamber is 52cc with 1.72/1.42 valves. Your compression ratio is your total volume at BDC divided by your total volume at TDC. This volume includes the plane of the gasket, the head's combustion chamber, the displacement of the cylinder and depending on the dish or dome on the piston, that must be accounted for too. Some pistons also don't quite come to level with the height of the block.

I think the 2.8 pistons at TDC are at 0.010" below the deck height...fyi

The pistons are hollow but with a bump in the middle towards the edges. The dept is about 7 mm. I made a closup pic for you to see.





What is now the best thing to do and why did it ran with the iron heads? Do i need new pistons? What will this gain? Whats the normal HP for this engine? Many questions i know but you are the only ones i can ask this. Here in the Netherlands there is little knowledge of these things

[This message has been edited by Gambit (edited 04-10-2013).]

A 2.8 behind a 5 speed with no mods brand new typically dyno's at 115 rwhp.
A 3.1 "stroke" upgrade will dyno typically at 125 rwhp with no additional mods.
A 3.4 "stroke and bore" will dyno typically at 135 rwhp with no additional mods.

With mods, we've seen a 2.8 put down 154 rwhp and a 3.4 put down 205 rwhp. It's all about what you're willing to invest.

quote Originally posted by Gambit: What is now the best thing to do and why did it ran with the iron heads? Do i need new pistons? What will this gain? Whats the normal HP for this engine?

There are others that know more about engines, but I will write this up and the corrections can come from others. The Fiero 2.8 iron head engine has the combustion chamber entirely in the head, and uses flat pistons. The 3.1 aluminum head engine has the combustion chamber split between the head and the dish in the pistons. Both engines were designed to be about 9.5 to 1 compression ratio.... If you use the iron head with the dished pistons, the chamber gets bigger, which reduces the compression ratio to maybe 7.5 to 1. The motor will make less power. If you want to use the iron heads, you should have flat pistons in order to maintain the original compression ratio.

Thanks a bunch guys for keeping track of my headache topic. I know now that these pistons wont work so i will let the machineshop bore it 1mm out to have a new cylinder wall and let them get flat top pistons.

What a bummer it aint no 3.4 but it is what it is and seeing the difference in RWHP it only losses 10 RWHP. Thats fine.

The thing that comes to mind is that IF this engine came with iron heads, does it still have the van heads or the fiero heads. If it has the stock, iron, van heads what is the CR? I have seen the fwd vans with 3.1 and 3.4 with iron heads.

The minivan heads would probably have 1.6" intake valves instead of 1.72" but are otherwise exactly the same. That is the only difference between HO (high output) and non-HO iron heads. The Fiero did come with 8.9:1 compression ratio stock vs. typically 8.5 (pre-3.4) for other cars. The Fiero 2.8 made as much power (140 hp gross) as early 3.1 motors...including GEN2 aluminum head 3.1 motors on FWD cars.

http://www.underhoodservice...spx?contentid=100681

http://en.wikipedia.org/wik..._60-Degree_V6_engine

If you want a nice power upgrade, get a 3400 engine rebuild it and replace those pistons with:
3.4 TDC pistons and Fiero heads with stainless steel SI valves available from the Fiero Store.

The stock cam in the 3400 engine makes much more power than most performance cams for the older motors and its a roller cam so it's a free cam upgrade as well. You can re-use the 1.6 roller rockers that came with the 3400 on the iron heads. You'll need intake and exhaust work to get good performance out of it but 180 rwhp is attainable with a ported Fiero intake and 2.5" exhaust with headers.
https://www.fiero.nl/forum/F...ML/075502-3.html#p98

[This message has been edited by lou_dias (edited 04-11-2013).]