95 Berlinetta weight reduction and modifications.

Pete is your top speed pro exhaust the titanium version?

 

Asked only because they advertise the titanium system at 7.15lbs so I was surprised to see your steel system coming in at 8lbs.

 

Finished the y-pipe and test fit everything.

Not sure that part was worth the trouble.

The stainless y-pipe I made with the spacer is 6lbs.

The titanium y-pipe is 2.4lbs.

Not using the exhaust hangers anymore, they come in at 3lbs.

So total weight loss of exhaust/y-pipe/hanger removal is 27.5lbs?

LOL. Next, -may- be rear subframe.

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I -really- thought my guides would be tight and valves sealing awesome based on my cars performance.

It ran awesome. Great numbers on the dyno and at the track. Didn't smoke or use oil.

That being said, I was really surprised at how bad the heads/guides are upon disassembly. Measurements? Have none. I didn't take any. Just observed that it was horrible and decided I need to fix it.

Also. I have not CC'd port volumes but have taken a bunch of measurements. From the start of the intake port to the guides, my early 2.7 heads are very similar in size to the later 5.2 head I bought.

After removing valves in my 2.7 heads, I've found the early heads seem to have a ton of material removed in the bowl area compared to the later 5.2 heads.

Also notable, (to me at least) is, while my early heads are much bigger in the bowl area of the heads, the quality of the work is unimpressive. Lumpy transitions and just looks rushed.

In comparison, the later 5.2 head I bought looks beautiful. Looking at the port work I thought, it would be hard to improve upon it. Just super nice.



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I don't think I will be able to capture the difference with photos. (I can try, don't think anyone could see the difference). Even looking at it in person it's hard to tell. Becomes more clear when you feel both of them.

Best I can describe it is, on the long side of the intake port, the 5.2 head has a perfect, long radius to the seat.

On my 2.7 head, that same long side overshoots meeting up with the seat. So below the seat/long side/top of port almost forms a bit of a bubble below the seat before meeting it. (overshoots then turns back to the seat)

5.2 head, appears ported by a master. Just super nice the entire port, on every cylinder.

One of my 2.7 heads looks to be ported very nice, but not quite as nice as the 5.2 head I have.

The other 2.7 head I have looks to be ported by someone else entirely with very little skill/attention to detail.

No worries, I will fix it myself. Just a bit surprised to see the variance between the 2 heads.

 

I believe they didn't seal well, all things considered.

Cold compression test was 150-170psi. Looking at the valves/ports there was evidence of poor sealing in the way of carbon/black traces up the valves.

As excellent as -some- of the port work is, the valve job on both the new and older head appears to me to be a single angle valve job. One angle seat cut and very wide margin.

I think that's why my car didn't exhibit any symptoms. Guides sloppy as hell....still... easy to seat the valve with no precision to the massive seat.

^ To your question, I would prefer to send them out. Problem is, I don't really trust anyone.

So from here I will order sample guides from multiple manufacturers to determine which I prefer.

I'll remove all guides from my heads then port them to match as best as I can.

Install best guides, then have the seats/valve job machined best as possible.



Not sure how much improvement will be found. Still surprised it made 340rwhp and (with weight reduction) ran 12.4 @ 116.8 with the above issues.

My best guess is the F355 valves could still do a decent job of sealing due to their small size. (and really less amplified by center valve 10deg retarded)


In comparison, same generation 2-valve (and basically hemi combustion chamber) Porsche, could suffer much more with same or less guide wear, I would think.

 

Thanks guys.

Starting to cut up the extra cylinder head I have to get an idea of port wall thickness...

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As for the port work I'm going to blend/smooth some of the lumpy work that was done but I don't intend to enlarge them any more than needed or re-shape significantly. The design looks very nice to me.

On the exhaust side I had header flanges made that match the exhaust port angle.

 

The stock exhaust port is, as mentioned, an upward angle relative to the flange.

The original headers do not match that angle so while the size matches fairly nice (header maybe slightly smaller than port) the angle does not, as you can see-

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The new flanges are- slightly larger.

Original primary tube OD I measured at 1.573 or 40mm

New primary tubes will be 1.625 or 41.27mm

Slightly larger but really only because 1.625 mandrel bends are as close I can find in the US without going smaller than original.

Focus is on, flange design being an extension of the port, rather than disrupting it, larger radius bends and slightly altering tube lengths.

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It appears my cylinder heads were ported by 2 different people, one much better than the other.

A few examples. Here is the exhaust port and short turn of the nice one.

Exhaust port is beautiful all the way to the flange. Bowl work/blending pretty nice.

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