This is kind of a second part to my post about power out my V6.

Whats the difference between the regular 2.8 and the H.O.? Is it just higher compression or is there more to it?

The second half of the question is, can I convert my regular 2.8 to a H.O. engine, or is that ludicrous? Keep in mind that my engine already has 150k miles on it.

if the 2.8 u are talking about is in your fiero then you already have the High Output motor, fiero is one of few cars to get the 2.8 V6 H.O.

hope this clears things up
~Mark

Like Mark said, the Fiero V6 is the L44 high output version of the 2.8. The only other place this motor had been used was in the old Citation X-11, but it was carb'd instead of injected. The main differences between the regular and HO version are the heads (larger valves), camshaft, and pistons (8.9:1 CR).

JazzMan

quote Originally posted by JazzMan: Like Mark said, the Fiero V6 is the L44 high output version of the 2.8. The only other place this motor had been used was in the old Citation X-11, but it was carb'd instead of injected. The main differences between the regular and HO version are the heads (larger valves), camshaft, and pistons (8.9:1 CR). JazzMan

Except in 85. Both the Celebrity and Citation got the same engine as the Fiero except with mass air flow instead of speed density. Same engine. The changed the TB, upper plenum and exhaust manifolds. That was about it other than was was necessary to mount it in the back.

[This message has been edited by TK (edited 10-05-2003).]

quote Originally posted by TK: Except in 85. Both the Celebrity and Citation got the same engine as the Fiero except with mass air flow instead of speed density. Same engine. The changed the TB, upper plenum and exhaust manifolds. That was about it other than was was necessary to mount it in the back. [This message has been edited by TK (edited 10-05-2003).]

So you're saying that those two applications used the large-valve head with the 8.9:1 CR pistons?

JazzMan

so the V6 fiero has 140 HP whats the HP on the NON H.O.?

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Rich AIM one fast 2m8
WTB: 3.32 4 speed tranny
I Need to find another Sig Pic. biengs another forum member has taken it upon them selves to steel it and re-word it and use it as their own sig with out asking

quote Originally posted by JazzMan: So you're saying that those two applications used the large-valve head with the 8.9:1 CR pistons? JazzMan

Yes. The W engine in the A/X and the S engine used in the F body (I forgot that one) are the same engine as the Fiero except for what I said above.

When GM was developing the MPFI engine they went for federal certification with both the mass air flow (6870 ECM) and speed density (6869 ECM). If one failed they always had the other as a backup.

Both passed and GM ran them both. They had problems with the mass air system and later years were converted to speed density. In some cars you will find a "Speed Density Conversion" sticker. The mass sensor was touchy to vibration and air flow (and failure). A working mass air system works very well. (I had one in my X-11 and I was able to change a lot without the fueling going all wonky. Also, the same system was used on the 85 Corvettes. Same ECM, etc.)

The speed density system is more reliable but less forgiving to engine changes without recalibration.

That's from a conversation I had with Jon Heinracy about the X-11 on how the HO LH7/LB6/L44 engines were developed. If it wasn't for the X-11, we wouldn't have the L44 engine. The HO came out of Jon's SCCA racing.

The original LE2 was 115HP. The LH7 was 140HP but was dropped to 135HP in 84(?). The LB6 was rated 135HP. The L44 was rated 140HP until 88 when it dropped to 135HP. The Fiero was rated with higher torque than the LH7 and a bit higher than the LB6 although they all seem to dyno about the same. The LH7 can wind higher due to the shorter intake runners whereas the Fiero weezes out.

I've never heard of a LO version of the MPFI engines. I know the various intake and exhaust systems of the MPFI engines produced varying HP and torque ratings, but I don't think a lower compression/smaller valve version was produced. Maybe someone can shed some light on that.

[This message has been edited by TK (edited 10-05-2003).]

No I haven't found a "small valve" EFI engine, either.

In '86 in the S-series trucks, when they received TBI the heads were "upgraded" to the "H.O." heads, and used until the demise of the iron head 2.8. Camaros also retained the same head for the 2.8 and 3.1, and as far as I can tell the 3.4, but some people say there are differences in the 3.4, which I have not been able to verify, it also seems that's something that doesn't effect the performance potential.

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The Raven :Under Construction
"James" 1985 GMC Jimmy, 3.2L turbocharged intercooled hybrid

"Speed Costs, How fast do you want to go?"

quote Originally posted by The_Raven: No I haven't found a "small valve" EFI engine, either. In '86 in the S-series trucks, when they received TBI the heads were "upgraded" to the "H.O." heads, and used until the demise of the iron head 2.8. Camaros also retained the same head for the 2.8 and 3.1, and as far as I can tell the 3.4, but some people say there are differences in the 3.4, which I have not been able to verify, it also seems that's something that doesn't effect the performance potential.

There is no difference between the Fiero 2.8L cast heads and the cast heads on the F-body 3.4L engines. I looked at both when I buily my 3.4L. They have the same 51cc chambers, the same size valves and the same casting numbers. There is a rumor that the chamber size on the 3.4HT crate engine is different, But I know it uses the same valves.

I'm pretty sure the 3.4L heads are the normal HO heads.