3.4 L32 V6/60... questions... compared to L44 (Page 1/9)
82-T/A [At Work] MAY 10, 02:47 PM
Ok, so I'm starting to re-think my own choices. I have a 3.2 that I've rebuilt, and thinking that rather than mess with that original engine, I could simply just go with a long block 3.4 (93 Firebird) that comes with a 4-year warranty that's been tested, and just build off of that.

So when looking at the power output, the Fiero engine puts out 140hp at 5,200 rpms; however, the L32 puts out 160hp at 4,600 rpms.

I realize the L32 is going to simply be quicker, just because it's more powerful, but what is the cause for the peak power to be at lower RPMs, and should I care? Back in the day, I've always enjoyed winding out the gears in my Fiero when it was a 2.8, and I always felt like it built power well into the 5,000+ rpm range. I would hate to think that all the power for the L32 (Firebird motor) is all in the low and mid-range? From what I understand, the cams are identical between the Fiero and the grind that's on the L32.

Aside from the fact that the intake would restrict a lot of the airflow (pretending that the intake was not the issue), is the mere bore and stroke of the engine what causes a lack of higher-rpm performance from the L32 versus the L44?

Note, I have an H272 CAM that I'd be looking to install on the 3.4 V6/60... I what kind of base power could I expect from the 3.4 (which is otherwise rated at 160hp)? Maybe 170hp?

I'd be happy, realistically, to get somewhere close to 185hp when everything is said and done. Just weighing my options.


I appreciate any thoughts... (other than a totally different motor, I want to use the Fiero plenum).
Thanks!
sanderson231 MAY 10, 02:59 PM
Spend $70 fpr DynoSIM5 software and you can get a better idea. My experience with it is if you put a bigger displacement block on the same heads, same intake and same exhaust you get a lot less power than you think based on displacement increase.

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formerly known as sanderson
1984 Quad 4
1886 SE 2.8L
1988 4.9L Cadillac
1988 3800 Supercharged

zkhennings MAY 10, 03:24 PM
Heads, intake, cams, and exhaust manifolds/Y pipe are all limiting. My 2.8 with the Comp 260H cam made peak HP at 5800 RPMs when I dyno'd it. I had mildly ported/gasket matched heads and intakes on mine along with ported exhaust manifolds and a custom Y pipe and 2.5" exhaust. I made 132RWHP which is probably about 160hp at the crank. This would probably equate to 185+ at the crank for the 3.4 at a slightly lower RPM on the 3.4 with my exact setup.

The dawg mod and boring out intake for larger 56mm TB would help too. I say go for it, not sure if LaFiera still offers his CNC ported heads for $700, but those with a hogged out intake + Dawg mod and 56mmTB will probably let the 3.4 breathe into the higher RPMs.

I don't think the stock bottom end wants to rev out super high but should be fine to make peak power near 6000RPMs for nice power overall for a Fiero without much effort and cost.

Double cut carbide burrs are a must for porting iron heads if you choose to port them yourselves, but for the aluminum intakes I would stick to the sanding rolls to avoid removing material too quickly. I get the kits with like 100 sandpaper rolls from Harbor Freight for dirt cheap.

An air die grinder is much nicer than electric as there is much less mass in the rotating components, which makes it much easier to not overdo it or make mistakes.

I like to move from port to port instead of doing each port one after another as it makes it much easier to stay consistent from port to port. It is probably 10-15 hours of work to port everything yourself, and less if you get already ported heads as they are the trickiest and most time consuming part of the job. Blending the bowls is a must as there is a wicked lip in the transition that really hurts flow.

[This message has been edited by zkhennings (edited 05-10-2023).]

82-T/A [At Work] MAY 10, 03:51 PM

quote
Originally posted by sanderson231:

Spend $70 fpr DynoSIM5 software and you can get a better idea. My experience with it is if you put a bigger displacement block on the same heads, same intake and same exhaust you get a lot less power than you think based on displacement increase.





Thanks, I'll buy that tonight. Never heard of that software.

So, I bit the bullet, and just bought the engine a few minutes ago... hahah.

In this case I bought the long block, so it comes with the heads. I think when you compare the exhaust for the F-body, the Fiero's exhaust is going to be a bit more open, but I think the intake is going to be a bit more restrictive. I do think I'll get more than 160hp, so I'm not concerned there... but I think I'm going to try to take advantage of some of the other improvements, like the fact that it uses a crank position sensor. I'm going to be using a newer / aftermarket ECM system, and that while I don't need to use that, I certainly can. I'll still be using the distributor though. It's currently capped off on the F-body engine, but the existing cam already has the gears for it. I would be looking to replace that though if I can get better performance with my H272.
82-T/A [At Work] MAY 10, 04:02 PM

quote
Originally posted by zkhennings:

Heads, intake, cams, and exhaust manifolds/Y pipe are all limiting. My 2.8 with the Comp 260H cam made peak HP at 5800 RPMs when I dyno'd it. I had mildly ported/gasket matched heads and intakes on mine along with ported exhaust manifolds and a custom Y pipe and 2.5" exhaust. I made 132RWHP which is probably about 160hp at the crank. This would probably equate to 185+ at the crank for the 3.4 at a slightly lower RPM on the 3.4 with my exact setup.

The dawg mod and boring out intake for larger 56mm TB would help too. I say go for it, not sure if LaFiera still offers his CNC ported heads for $700, but those with a hogged out intake + Dawg mod and 56mmTB will probably let the 3.4 breathe into the higher RPMs.

I don't think the stock bottom end wants to rev out super high but should be fine to make peak power near 6000RPMs for nice power overall for a Fiero without much effort and cost.

Double cut carbide burrs are a must for porting iron heads if you choose to port them yourselves, but for the aluminum intakes I would stick to the sanding rolls to avoid removing material too quickly. I get the kits with like 100 sandpaper rolls from Harbor Freight for dirt cheap.

An air die grinder is much nicer than electric as there is much less mass in the rotating components, which makes it much easier to not overdo it or make mistakes.

I like to move from port to port instead of doing each port one after another as it makes it much easier to stay consistent from port to port. It is probably 10-15 hours of work to port everything yourself, and less if you get already ported heads as they are the trickiest and most time consuming part of the job. Blending the bowls is a must as there is a wicked lip in the transition that really hurts flow.





Thanks for the info! I appreciate it! Yeah, I have the 56mm throttle body (or whatever it was) from way back in the day. There was a guy in the early 2000s who was doing these, his name was Darrel Morse. I went with his kit where he bored out the existing throttle body, and well into the intake plenum. That said, and like you said... it's still the neck that's the problem... so I will definitely have to do the dawg mod. I've never welded with aluminum, only have a basic mig welder, but hopefully it shouldn't be too hard.

I've already done port-matching of all the intake components from intake to plenum, but I'll go over it again to smooth it out with the rollers like you said. I'm nervous about doing it to the cyl heads, especially since this will be a long block, do I really want to remove the cyl heads, haha... but I might as well.

"Blending the bowls is a must as there is a wicked lip in the transition that really hurts flow."

I remember hearing about this. Do you have anything I can reference? Is there a good write-up anywhere on this?


"I don't think the stock bottom end wants to rev out super high but should be fine to make peak power near 6000RPMs for nice power overall for a Fiero without much effort and cost."

When you say this, you mean the 2.8 and 3.4 in general, or the 3.4 more so than the 2.8? Yeah, 6,000 rpms would be perfect, I wouldn't want to go more than that, I'd just like to know that I'd be able to continue to produce some kind of power through the mid-5,500 rpm range.

~185hp, as you kind of eluded to, is really all I'm looking for. I would be very happy with that. As others have said in some other threads... I'm getting older, and what I want has changed a lot. It used to be back in the late 90s, I viewed my Pontiac Fiero as a serious sports car and something that was super awesome... and I'd cruise all around Miami and race Porsche 944s and Mazda RX-7s and other cars and I just thought I was the **** . I'm in my mid-40s now, and I recognize that a 200hp Accord Sedan would leave me in the dust. At this point, I just want my Fiero to "feel" like it did when I was a kid, run well, and have fun with it... I won't be winning any races out here in rural Tampa!
cvxjet MAY 10, 04:49 PM
I know that the High-rpm fans will tell you all day long that "Spinning the engine is the only way to GO!" but....I have the 3.4 F-body swap that nets you 20 more horseys and 30 Lb/Ft of torque.....This would not even knock a second off your 0-60 time...But I am a full second quicker and that was with a bunch of Cat-Crap in my exhaust and the stock intake- I have now opened the pinch point in the intake and shaken out the exhaust....i suspect I will then be at 6 seconds vs the stock 7.5 0-60.

Having your power-band at a lower RPM is just like installing a better gear ratio in your final drive.....But without the buzzing down the freeway at 4000 rpm @ 60 mph.

Also, lower RPM engines will generally have a wider power band, while the high RPM engines have a very narrow band; My 3.4 is over 100 HP from 2500 to 5000 (Half the rpm band)....The Honda Del Sol 1.6 L four has the same 160 HP (But at 7500) but the cripling thing is that the torque peak is at 7000....It is over 100 hp from 6000 to 7500(1/5 the RPM band)....every time I shift I stay ABOVE 100 HP, while the Del Sol drops to 78 hp (1st-2nd) 83 hp (2nd-3rd) 90 hp (3rd-4th) and finally on the 4th to 5th it is close to 100 at 98 hp.
zkhennings MAY 10, 05:26 PM
I was referring to the 3.4 would probably be happy revving out to 6k if it can breathe, the 2.8 can probably go a little higher due to rod/stroke ratio and lighter pistons.

Check out Eric Weingartner's vids, super informative. The iron heads are exceptionally egregious when it comes to extremely poor blending of where the valve seat has been machined relative to the cast port bowl that is flowing into it.

There are several vids in this series:

https://www.youtube.com/watch?v=-Y5RODX3L0k&t=1s

Also I disagree about cars making power low down having longer power bands. It really depends on all the mods and the cam. I think what you really mean is that high hp low displacement screamers make very little torque at any point and make all their hp at high rpms. With 3.4 liters you will always have torque and if you can use cam and flow to extend that torque into higher rpms, you will make more horespower.

Here is my dyno graph, as you can see even though peak hp is close to 6k, it is making torque the entire time. This is what you want, a torque curve that peaks in the middle and is sustained across the rev range.



You don't want a flat HP graph, you want a flat torque curve and a linear hp curve that is constantly rising until your ideal shift point. In fact even if you do sacrifice bottom end torque, it only helps save the drivetrain and makes the car more driveable as you aren't lighting up the tires coming out of a turn as you get on the gas. A torque curve that is falling the entire rev range (flat hp graph) will only feel like the car is pulling slower as you climb up the revs. Flat torque curve makes the car pull hard at all times. Do you want your Fiero to feel like a diesel truck or like a sports car?

[This message has been edited by zkhennings (edited 05-10-2023).]

lou_dias MAY 10, 06:51 PM
The F-body 3.4 is stuck at 160 hp out of the box because it's still using a stock Fiero cam and ports cast for 2.8L worth of flow.

The 3X00 v6 engines have technical differences that give them more hp out of the box:

- A roller cam with roller lifters and more cam lift to match the exhaust lift and 1.6 ratio roller fulcrum rockers
- A smaller diameter crank pulley.
- Valves with a thinner valve stem which inherently flow more air for the same diameter valves.

The 3500 that is related to the 3900 also uses narrower rods and is a lighter rotating assembly giving it a few more HP over the 3500 that is based on the 3400.

They all use higher compression than the F-body 3.4

If you were willing to apply these enhancements to a rebuild, as I and La Fiera (and originally Fierosound) have, you'd make comparable power as we have shown.

I actually use 3400 blocks since a rebuild is planned anyway and hence use the roller cam setup as Fierosound detailed. The starter holes are already on the correct side.

The stock Y pipe sucks too...

You'll still need to modify the intake and throttle-body for more flow though. That's unavoidable as again it was barely good enough for a 2.8L engine.

[This message has been edited by lou_dias (edited 05-10-2023).]

pmbrunelle MAY 10, 07:05 PM

quote
Originally posted by zkhennings:
I don't think the stock bottom end wants to rev out super high but should be fine to make peak power near 6000RPMs for nice power overall for a Fiero without much effort and cost.



To my knowledge, the bottom end of a DOHC LQ1 spins to 7k and is the pretty much the same as the bottom end of any other 3.4.


quote
Originally posted by lou_dias:
I actually use 3400 blocks since a rebuild is planned anyway and hence use the roller cam setup as Fierosound detailed. The starter holes are already on the correct side.



Why aren't you using 3400-based 3500 LX9 blocks for your iron-head projects?

For that matter, why hasn't this caught on in a larger sense?

Does this not work?
lou_dias MAY 10, 07:13 PM

quote
Originally posted by pmbrunelle:


Why aren't you using 3400-based 3500 LX9 blocks for your iron-head projects?

Does this not work?


Yes, I just overbored a 3400 to 3.7" aka 3500. I also had the rod journals turned down to 2" so I can use 3500/3900 style lighter rods and my crankshaft lost 6.5 lbs after balancing

It hasn't caught on because most Fiero owners are cheap. They'd rather spend 20 years on one swap with a used engine than a few months and some coin on a proper performance rebuild with essentially a brand new engine.

[This message has been edited by lou_dias (edited 05-10-2023).]