Camshaft selection 60deg V6

[Kraniet]

Im doing up an 3.4 liter V6 for my Fiero.
Im basing it on the camaro L32 but will only use the block, crank and conrods.
The heads will come from a 3400 engine from the Transporter. Ill also use its intake manifold.
Will do some light porting on the heads and plan on using a flatter intake valve (from the 3500 engine).
Plan on using dual secondaries down to a high flow cat and a bigger muffler.
Long tube headers or ported exhaust manifold.
Using dished pistons, 92.5mm. And should have a static compression around 9.7.
Using stock th125 3-speed with stock converter.
Aiming to use comp rockers with roll tip.
Going to use a custom engine management(maxxecu)

I kinda like the power curve as it is but would like more bottom end torque and more top end.
Stock the engine has max torque at 3600 and max power at 4500.
Stock cam is 196/203 @50, 276/293 109 LSA. Hydr flat tappet

I know that the crane 272H produce good power on the 2.8.
Thats 216/226 @50. Blueprinted 2.8 engine with ported stock manifolds and dual exhaust produced 107 whp@3500 and 142 whp @5000. (Thats +13 and +37 whp over stock) According to an article in some magazine back in the day.
Those results were with the less flowing iron heads.

So seeing how I have .6 liter bigger engine. My thinking was something like 218-220/216-218 @50, 270/270 111 lsa (50 overlap)
Thats going by whats suggested in books by David Vizard and Graham Bell.
There seem to be possible to get a custom grind from Howards via Summit.

Any and all suggestions and advice are much welcome.

If youre interested in the build I have an instagram called magnus_fiero
Plan to build it this winter and do the engine swap after that.

[Walter R. Malik]

Im doing up an 3.4 liter V6 for my Fiero.
Im basing it on the camaro L32 but will only use the block, crank and conrods.
The heads will come from a 3400 engine from the Transporter. Ill also use its intake manifold.
Will do some light porting on the heads and plan on using a flatter intake valve (from the 3500 engine).
Plan on using dual secondaries down to a high flow cat and a bigger muffler.
Long tube headers or ported exhaust manifold.
Using dished pistons, 92.5mm. And should have a static compression around 9.7.
Using stock th125 3-speed with stock converter.
Aiming to use comp rockers with roll tip.
Going to use a custom engine management(maxxecu)

I kinda like the power curve as it is but would like more bottom end torque and more top end.
Stock the engine has max torque at 3600 and max power at 4500.
Stock cam is 196/203 @50, 276/293 109 LSA. Hydr flat tappet

I know that the crane 272H produce good power on the 2.8.
Thats 216/226 @50. Blueprinted 2.8 engine with ported stock manifolds and dual exhaust produced 107 whp@3500 and 142 whp @5000. (Thats +13 and +37 whp over stock) According to an article in some magazine back in the day.
Those results were with the less flowing iron heads.

So seeing how I have .6 liter bigger engine. My thinking was something like 218-220/216-218 @50, 270/270 111 lsa (50 overlap)
Thats going by whats suggested in books by David Vizard and Graham Bell.

For those 60 degree GM engines, most of the time, I have used the Generic 204/214 cams available from a lot of places.
Using 1.6/1 ration intake rockers and 1.5/1 ratio exhaust rockers

[Kraniet]

Thats good to know. Thanks for the info.
Whats been the reasoning behind that cam choice?

Do you know what kind of power figures that renders?
Also is that on carb or efi? If efi, was it stock tune or custom?

[Xnke]

Go with the Crane HMV or Z profile grinds. I used to have a chart posted here back when I did my supercharged 3.4L build in the S10. GM used to ship the 3.4L crate motors for S-10 pickups with a Crane 260H grind, which was the H-204/2847 lobe profile on both the intake and exhaust.

That supercharged engine did 278HP and 301tq from a 3.4L with 3500 heads/lower intake/M90 blower on the upper, at 8lbs of boost, and used a Crane H-210/2934 intake lobe, and the H-272/3027 exhaust lobe, ground on a 114LSA. Smooth idle at 800RPM with the blower unloaded, and would close the bypass and load the blower at 1800RPM, made 8lbs of boost by 1900RPM, peak torque was at 3200RPM and peak power at 5500RPM, and I was still able to tune in over 30MPG highway with the manual trans and 3.73 rear gears.

Skip the 3400 heads and go straight for the 3500 heads and 2004+ lower intake manifold, it's worth 24CFM unported. The biggest advantage is the exhaust port on the 3500, and the improved lower intake manifold. You get a little gain in the intake port too, but not as much. The comp cams rockers aren't needed, just run the stock 3500 rockers as they're the LS-1 style and do very well. Even the gnarliest cam you can get on a stock size bumpstick isn't going to see much gain from a roller tip rocker.

I used the factory GM ECU from the 95-96 camaro, with custom firmware and Tunerpro to do my tuning. I have modified the firmware to allow use of the 2 and 3 bar MAP sensors, fixed the bug that tied injector reference voltage to the fuel pump voltage instead of battery voltage, and extended the fuel and spark maps to 6400RPM and up to 300kPa. Also patched in wideband O2 datalogging support, so you can tie in the wideband O2's output and datalog that with all the other data coming from the ECU.

With the compression only being 9.0 to 1 (if you are using the 3400 pistons as I suspect, aftermarket pistons will have a larger dish in them to compensate for decking the block and heads 0.010") I would go with the Crane 272H, going bigger is going to make for a bit soggy bottom end. the 272H uses HMV lobe profiles and is the same series of lobes that the 260H is ground from, just the bigger lobe. It's "crate motor friendly", I mean to say.

If you use the factory 3.4L camaro pistons your compression will be 11.2 to 1, and you will need premium fuel to avoid knock (but only need 28ish degrees of timing with the 3500 heads, more timing does not make more power) but can make use of the larger H-230/324 lobe for your intake without worrying about the cam getting to soft down low. I'd go with a H-230/324 lobe for the intake, H-236/327 lobe for the exhaust, and put it on a 109 or 110 LSA, if it was my engine in the high-compression configuration. These cam lobes are also the Z profile and will need tougher springs for sure-I used the PAC 28918 LS-1 style beehive springs and they were perfectly fine up to 6000RPM.

You could go bigger, but you start running into lift getting high enough to crash retainers and valve seals, and have to look at sinking the spring seat down to get the valve seal down on the guide lower.

It is very easy to get a stock 3500 engine to nearly 400Hp by adding a GT3582R turbo and running about 15lbs of boost, but it's not easy to get there on a 3400...since 100cc's isn't going to make that big a difference, that should say something about the heads and intake the 3500 got!

[Kraniet]

Cool. Very good info.
Sounds like some engines there.

Ive read about how the 3500 is much better. Unfortunately those engines are very hard (expensive) to come by in Sweden.
So Im going with a ported set of 3400.

Im going to build a custom plenum with one chamber per bank. Then use the opel vectra tb with dual throttles. Thinking about using the resonance valve also and run two intake pipes from airbox to tb via the valve. That way optimize the ram effect for two different rpm. Not sure if it will make a difference, but itll be cool
Im building a new airfilterbox in the wheel well.

My measurements on the pistons and heads puts my compression around 9.7.

So might be able to go a little higher than the 216 of the 272H?

Well happy to see youre in agreement with my initial thoughts.
Ie 216-220 duration with approx 50 overlap

[CamKing]

Go with the Crane HMV or Z profile grinds.

Crane Cams is no more.

[Kraniet]

Go with the Crane HMV or Z profile grinds.

Crane Cams is no more.

Yes but there are cams with similar duration and lift. As for the profile thats unknown..

[Kraniet]

Sorry for the double post. But Im still trying to figure this out.

If one looks at this old article where they changed cam in the 2.8, they used a cam similar to the crane H272
272/284 adv dur, 216/226 @ .050" med 0.454/0.480 lyft. ICL/ECL 107/117
Wich seem to get on the came at around the same rpm but extend power quite a bit.

fierocam_1.jpg

A rule of thumb is that you add/subtract 4 deg for every 30 ci change in engine size to get the same behavior from the cam. In that case that would call for 219/230 for the 3.4.

Another example is a 231 V6 camshaft. A voodoo cam that says:

Hydraulic Flat Tappet. High performance street/strip cam for 231 c.i. Excellent camshaft for cruise night. Needs 9:1-9:5 compression ratio, 2000 stall speed converter and 3.42-3.73 rear gears. Cam has a very choppy idle quality.; Advertised Duration (Int/Exh): 262/276; Duration @ .050 (Int/Exh): 219/227; Gross Valve Lift (Int/Exh): .484/.505; LSA/ICL: 112/108; Valve Lash (Int/Exh): Hyd/Hyd; RPM Range: 1600-5800; Includes: Cam Only

If I convert that down to 207 ci it would mean 215/223. So it all is in that same ballpark, or so it would seem.

But one must remeber that those cams were made for stock engines with stock ecu. How does a modern aftermarket ecu change the game (at all)?
Also I understand that longer adv duration is kinda "old school" thinking and that a smaller difference between adv and .05" dur is better?
If Im not mistaken it was UDHarold who designed the Voodoo series? His view was most certainly that the cam should be like that.
Wich also is evident in that voodoo cam even though it seem less "radical" than his own cams.

And for the last question. What is the "final verdict" regarding cams with longer exhaust? Should I rather go for an equal cam or even shorter than intake? How much difference does it make?
On the one hand it seems like more exhaust can give the engine more extended power curve above hp peak (something Im not really concerned with if it means less low speed torque).
On the other hand some say it might hurt power and give less economy.

Maybe Im just overthinking it. I assume these are small differences. I most certainly dont want to over cam the engine, but at the same time you always want that "optimal" result..

[Xnke]

Go for the 219-220 degree intake, 225-228 degree exhaust.

I assume you've looked at the head flow numbers, and noticed that your aluminum heads flow much better on both the intake and exhaust than the iron ones in that article.

You don't need as much exhaust bias for the aluminum heads, as the exhaust port is much better than the iron heads. The intake port is quite a bit better too but the exhaust got MUCH better.

There is no significant advantage to a "carburetor cam" or a "Computer cam" as long as you can tune/adjust the carb or computer. Also, those cams were not "Made for a stock ecu" the stock ECU has absolutely zero ability to compensate for the cam if you don't plug in and adjust values yourself.

As long as you have a tunable engine control computer/carburetor, use any cam that fits your usage of the engine and tune it appropriately.

[Kraniet]

Thank you for the input.

Yeah the aluminium heads flow like 30% more on the intake and something like 40% on the exhaust.
With some minor porting and change of intake valve I assume it will improve even more.

On that note I read the 50 degree seat thread and started wondering if I should go that route. The new valve is a bit larger so a 50 deg seat would make it easier to fit. Also it might bias the flow more to mid/high lifts and cut down on reversion. Making a longer cam appear smaller at low lift but still give mid/top end.
But Im not sure if I can convince the machine guy to do it.

Here is the thread.
viewtopic.php?f=1&t=53485

An article comparing 30/45/50 deg seat
https://www.motortrend.com/how-to/1203p ... valve-job/
As can be seen the 50 deg seat perform overall best for 3500-6500 in that test.