Skimming Heads 3.2 V6 Busso

[Saabretooth 8]

I'm just struggling as to why you wanted to increase the compression and lower the volume, another down side to skimming the heads is that the cambelt tensioner only has a certain amount of movement, skim too far and you'll never get the belt tensioned (unlikely but possible), the questions your asking though really do make it sound like your being taken for a ride, but the mechanic is doing the right thing in replacing the gaskets, the problem is that you are looking for an increase in performance and this is not going to happen with the work being done, the 3.2 was setup in design as well as it would safely go, everyone who has tried tweeking them has had catastrophic results, Alfa themselves went as far as 3.5 and we found that the lumps cooked, almost all the 3.7/3.8/turbo/supercharged conversions I've seen or heard about have gone bang, very few still remain and they are mainly in South Africa. The worst though are the copies of the Autodelta 3.8 kit touted by members of another forum, I've yet to see one of those run nice and reliably.

 

Which is true to the extent that you have you explained it.

 

I've only taken off about 1.0 to 1.2mm, increasing the compression to about 11:1 from what I read, from internet and other spec sheets of the GT.

 

Together with the re-profiled cams, I am looking at about a 10-20, or if optimistically 25hp gain on the current 265hp (with CF2 manifolds) that I have.

(this includes the 78mm Throttle Body and 4.5L Plenum which is going in at the same time.)

Edited September 29, 2013 by Saabretooth

[Saabretooth 8]

On the same note,

 

As I am setting the car up for high torque and higher hp, I also want the air flow to be smooth through the manifolds.

 

What would the difference be with the stock CF3 manifold with punched through cats vs the CF2 manifold?

 

My guess is that the chamber with the punched through CATs will create an irregular pulse phase as the exhaust gasses move, creating a slow down in air velocity. thus lower hp, and probably a bit more heat in the chambers.

 

What would you say Smaky?

[Smaky 73]

I think your on the right lines there, you'll only affect the pulse, and lowering the back pressure decreases the fluid drag of the gases through the engine so yes it will increase the temps within the engine, seeing as you can only let out what comes in because the main restriction factor is the shinny ducts, stub manifold and valve diameters, without changing those all this other work will be meaningless, as it is I predict a fall in grunt and a power band very narrow in the rev range as you'll have to increase fuel % to keep the temp down..

[Saabretooth 8]

Thanks.

 

One of the mechs suggested that I put back the old manifolds with the punched out cats. I'm thinking not to as I don't want that pulses to affect any other the other work I've done.

 

I've also got access to larger exhaust valves, but I am keeping that option off the radar, as I'd like to still have usable power in the lower RPM range.

No porting of the heads either, as the stock 3.2 is big enough to accomodate. Unless I am building a race car and would need it to be bench flowed. which I don't. Its more of a fast road, occasional track day machine.

 

I was even offered ITBs, but that would definitely be an overkill for my application, and the db levels will alert the authorities to what's not allowable underneath the bonnet.

 

Will take note of what you mentioned and keep an eye out on how the car performs once its out of the workshop and properly dyno-tuned.