3.2 SS build Approx. HP & Torque estimated anyone

[CBA]

Hi There,

This is the build I've committed too. I know there are many different ways to do it with a different P&C setup, cams, twin plug, etc, etc, the only change I will probably do is go to a larger headers, but this is the road I'm taking and will give it the try. If it isn't right I'll take it as an expensive lesson learned.

The build's goal while probably not perfect in this community but it is what it is. The goal is a fun motor that hopefully (I've always been told hope is not a strategy ) that I can beat on, run hard, and drive day in and day out.

Here are the specs:

1983 3.0 motor Specs/build 66,000 original miles.
* 91 Octane(Pump Gas) add Boostane Fuel additive to 100 Octane.
* Bottom end remain stock.
* Mahle PS98-015 3.0 to 3.2 10:1 p/c set CIS style dome
* Billet cam 964 billet camshaft set 964 C2/4 grind
* Single Distributor modified with no vacuum and mechanical advance from 0 to 30
degrees.
* 46mm PMO carbs.
* Head ported to 38mm.
*SSI Headers for heat, but will probably go with larger headers.

I've done what I think is my best research. What kind of HP and Torque do you guys think I should see out of this? This piston / cylinder combo is somewhat new(from what I can tell) and haven't read anyone who has this setup yet.

Thank you

[Neil Harvey]

""If it isn't right I'll take it as an expensive lesson learned.""

There is so much wrong with that statement on so many levels.

In my opinion you have it backwards. I think the question you should be asking is, my performance goals are this, what parts will I need?

The two questions I ask potential customers are, what are your performance goals and what is your engine budget? From here you can decide upon the parts required and make any compromises to fit the budget. Typically, the two are miles apart, mostly from lofty performance goals based on false information. This is the slippery slope so well known.

Deciding on the performance always seems to be about max horsepower. Its great to have it, but how often will you use it? Unless you are building a race engine and your competitors have “X” HP, think about your use and how often you will need max performance. The histogram feature in some EFI systems becomes very useful tool for this.

For a street use, I suggest you consider low and mid-range torque, select an RPM limit that’s more conservative, and really work on the engines throttle response. A short-stroked engine will rev quicker in comparison but will limit the engines torque production.

Depending upon the engine’s induction parts, it could really hurt street use. This may be way “off base and a who cares” type of thing, but this could be the result after you have spent your hard-earned cash.

What you have is a piston that will move from TDC to BDC over a shorter distance, less cylinder volume, (bore not considered), therefore the pull on the induction will be less over time per the same crank angle. The depression from atmospheric and the engines pull towards vacuum as the piston changes direction is what you need to think about. A shorter CCL rod will help here, but the shorter stroke is working against this. So, you add in more piston compression height but now you’re adding weight to the piston, the worst weight as it all over and above the pin. Now you need to think about how you guide the connection rod to help keep the piston straighter in the bore.

This will also require a cam to best match what you have, so lift will help here. Because the piston will move down the bore less, per crank angle you want more valve movement. Duration may hurt as the valve opening longer will allow the pressure differential between the intake and exhaust to equalize and slow down the intake and hold some exhaust gasses in the cylinder. Now you are filling an even smaller volume as some exhaust gases remain, increasing the chances of some detonation with pre heated gases, and lowering the engines torque production.

All “kinda” full of maybe’s, but these are the things that should be considered when choosing the engines configuration and parts. Yes, there are many success stories out there, but these are often masked with some undisclosed disappointment. Who wants to admit they should have done it differently? And, it always can be done better if better is known and available.

Talk to your parts supplier and get their opinions and past successes, if you have an engine builder in mind, ask them for advice and most importantly of all, decide upon your performance goals and your budget first.

[Jonny042]

The choice of CIS type pistons and a "smog" cam is a bit strange, unless you happen to already have the parts. Most people would go with a JE piston (or similar) over the CIS style dome, and a bigger cam, especially considering the 46mm carbs.

3.2SS twin plug underway

A pretty good read.

[Trackrash]

Using stock pistons and cams (even 964) would be a waste of time with 46 Webers, IMO.

9.5 JE pistons and a mod S cam and you will have a screaming motor.

If you have Bruce Anderson's book there is a dyno chart with this configuration.

[CBA]

Thanks for the input guys...dome style pistons as I originally was going to stay with my CIS... they were already bought...... also choose Mahle as they are much debated the best...... I'm not here to debate it on here. Decided to throw carbs on for fun factor. Wanted to see if anyone has done a build with a similar setup and what kind of numbers they were getting... that was it not much more or less.

It's all about longevity, reliability and decent power gains for me. Agreed I could have built a screamer motor with more power and excellent read that was attached. Thanks. Just was curious if someone had done a similar build and maybe did a dyno on it. It has been suggested it will be in the 220 to 230 range.

[Nux]

Originally Posted by CBA

It has been suggested it will be in the 220 to 230 range.

It should be.

With the asymmetric domes (which were made specifically for CIS and single plug) you are limited to 964 cams or webcam 20/21 or DC20 -maybe 993SS.

I'm sure you will have a fun engine, but it could have been even more fun without changing the budget if you had chosen differently.

[Bigtoe32067]

You can get new pistons for a grand so why waste the rest of the engine over a grand especially when you can sell the pistons you have to recoup the cost of new pistons.
Same with decent cams
Might as well run cis with your config and save the 4K from the Weber’s.