"New" 2.8/3.4 Cam Option (Page 2/3)
La fiera APR 27, 08:45 PM

quote
Originally posted by Will:

A big thing that needs to be stressed is that with the same heads, the bigger engine will lope less with a given cam.

So if a 2.8 with the 272 doesn't lope as much as you thought, then a 3.4 with the same heads and cam will be even smoother.



Displacement has a direct effect on cam attitude, heads will make a difference in the power band. Between a 2.8 and a 3.4 it's almost the same.
Now, if you install the same cam in a 5.7 then the difference is obvious. Displacement dictates cam attitude not much heads.

Will APR 28, 12:52 PM

quote
Originally posted by La fiera:

Displacement has a direct effect on cam attitude, heads will make a difference in the power band. Between a 2.8 and a 3.4 it's almost the same.
Now, if you install the same cam in a 5.7 then the difference is obvious. Displacement dictates cam attitude not much heads.



The 5.7 is an apples/oranges comparison, not least because a 5.7 has 8 intake ports vs. 6.

If you have a given intake/heads/cam/exhaust combo on a 2.8 and it idles with a lope and makes peak power at whatever RPM, then put that combo on top of a 3.4, it'll have a smoother idle, more torque, similar to slightly increase power, but at a lower RPM.

The percentage change of a 2.8 to a 3.4 is the same as the percentage change of a 350 to a 427.
La fiera APR 28, 04:39 PM

quote
Originally posted by Will:
The percentage change of a 2.8 to a 3.4 is the same as the percentage change of a 350 to a 427.



The percentages may be the same but the difference in displacemt is double.
From the 3.4 to the 2.8 there's only 600cc difference, from 5.7 to 7.0L there is 1300cc.
Same cam with 1300cc differences between engines will change cam behavior,
with only 600cc there will be a difference but very unoticible.

But you are correct, it makes a diffence proportional to an increase on displacement.
Lilchief APR 29, 10:36 PM
The cam your looking at will have a slight lope. I used a federal mogal cam in my 3.4 spec at 214/224, 112, 443/465. Had alot of torque 250+ at the wheels. But that's with alot of mods. You will have to have a custom chip made.
Hope this helps
BillS MAY 01, 03:20 PM
There is very little lope with the 272 cam profile.

But you do need to do bunch of other things to improve breathing before you are going to get much benefit from it. Like optimizing the entire intake tract, port matching, etc. My 3.4 no longer runs out of breath like a stock one - it pulls cleanly to 6,000, but I did extensive intake work (using a hogged out F body intake) and larger throttle body as well as a bunch of exhaust work.

Frankly, the 260 cam would be a waste of time.
La fiera MAY 01, 09:21 PM

quote
Originally posted by BillS:

There is very little lope with the 272 cam profile.

But you do need to do bunch of other things to improve breathing before you are going to get much benefit from it. Like optimizing the entire intake tract, port matching, etc. My 3.4 no longer runs out of breath like a stock one - it pulls cleanly to 6,000, but I did extensive intake work (using a hogged out F body intake) and larger throttle body as well as a bunch of exhaust work.

Frankly, the 260 cam would be a waste of time.



Pulling cleanly to 6000 doesn't mean its making power at 6000 but you got a point, the intake system has to be uptimised.

Modesto MAY 02, 09:30 PM
I find it odd people keep saying the intake needs a lot of work to really get anything out of the 272. The article that Dave Gunsul has posted a few times shows a pretty healthy jump on the 2.8 with no intake mods at all. Does this just apply to the 3.4? I don't understand enough to know how that increase in displacement would impact things.

I've seen posed here many times that the stock intake system I'd good to 190 hp, which I would think is more than enough even with a 3.4 and the 272 or equivalent cam. But again it could just be my ignorance showing through. Regardless I know larger gains would be realized if everything was optimized for the cam, but the 15 hp showed in the article for the 2.8 seems pretty darn good!
Patrick MAY 02, 09:41 PM

quote
Originally posted by Modesto:

I've seen posed here many times that the stock intake system I'd good to 190 hp...



Just to be clear, you're referring to the stock intake system on a Fiero 2.8 V6?

Modesto MAY 02, 10:15 PM
Unless I misread, that's what I understood was being referred to.

Edit: The page on pontiacperformance.net specifies the stock intake plenum is limited to 190 hp, so maybe the lower intake and heads are not? I believe when I have read it posted here it was somewhat ambiguously said that "the stock intake is limited to 190 hp". However one wants to interpret that as it pertains to the Fiero...

[This message has been edited by Modesto (edited 05-02-2020).]

Patrick MAY 02, 10:20 PM

quote
Originally posted by Modesto:

Unless I misread, that's what I understood was being referred to.



I suspect you misunderstood something. The "neck" of the Fiero's upper intake is well known to be quite restrictive.