308 QV head porting

Excellent information!!

I'm figuring out how best to read this information.
Any comment on flow velocities as well as peak flow rates?

Many many thanks for the great work. This will be a benchmark thread as no QV porting info available as I know.

 

Great News Mark. I am anxiously waiting for this info before I start on my engine. Thanks for all the helpful info. It will be nice to make more hp at lower boost levels. 14 psi with proper head work for me should yield some good results.

Paul

 

I'm completely new to this, but I have heard stories that 'porting and polishing' heads is an old hot-rodder's trick to improve airflow in the engine, and thus increase horsepower. However, when I asked the local wrenches here at Boston Sportscars about the benefits of Porting and Polishing heads on a Ferrari, they said the benefits weren't there and I shouldn't bother. The engines on these cars are so well-engineered, that such tinkering won't provide the bang-for-the-buck 308 owners are looking for to get a few more horses. True??? NOT???

 

Depends on what you want, and how much your going to do yourself. I think most of the guys here who are interested in more performance, are generally doing a lot of thier own work. Yes, the engines are well engineered, but good engineering doesnt always mean good performance. The 308 barely makes over 80HP per litre, or roughly 1.3 HP per cubic inch. Compared to many other engines from other manufactures thats pretty dull. I had a stock Renault when I was a kid that made that much. But if your going to start paying someone to get one of these engines to make more power, then I would have to say its not worth it. You could trade a decent 308 up for a 348 and have money left over for what you would pay someone to find 30 more HP in a 308.

 

Another thing Kermit mentioned was to make the inlet port more like the inlet port of the 348 - he said it works better as an oval than a more "8" shape.

It might be interesting to provide the machine shop with an old 348 intake gasket as a suggested port shape.

Right now, I would like to combine reshaping and polishing the port, matching it to the manifold and a radiused valve job. Since I really do not want to remove the engine and do pistons, I may shave the heads slightly for a quarter point - half point or so.

If I can get 10 - 15% with the same or hopefully more low-end, that would be worth it.

 

It all looks very interesting Mark! Thanks for posting your results so far.

I've been on the road a lot the last couple of weeks but this weekend I 'll be boxing up one of my cracked 2V heads to ship to Vick for a little flow bench testing.

 

Hi Mark, and others,
Anyone know about how good the standard 328 heads are? Anyone done some flow work on them and got some extra hp as a result? What sort of percentage increase???
Cheers,
Grahame

 

Yeah! Let's wait and see what he does!

 

Oh, hi there Russ! I hadn't realised that your comments on this thread were from a 328 perpective. I'm curious to see what might be achieved. So far, it woud seem that maybe a conservative 10% increase could be achieved, but it's definitely not amateur hour stuff, with the potential to push too far into the water jacket, etcetera and it seems that it must be flow-benched to be really effective. So I think I am learning something so far.
Cheers,
Grahame

 

I whole heartedly agree - there is a lot of opportunity to bugger up some damn expensive heads, so we are fortunate to have Mark and Vik doing the development. It may prove not to be cost effective, or it may be the Mother Lode of flow and velocity.
I know I am also learning a lot.
best
Russ
"Send Anzac Biscuits!"

 

The Ferrari engine heads don´t have much to do like commom cars engine heads. The guide boss and seat troat was very optimized. The best that can do is add 30 degree back cut at the valves above 45 seal degree, and smooth(polish) the exhaust ports, and re-shape(don´t polish! only get badder the air/fuel emulsification) the inlet ports and seat troat.

But some heads you can get a very high power results. I did a headwork on a Opel 8V head(2 liter OHC, 4cyl engine), and from standard 110bhp of factory power, gone to 153bhp comproved on dyno rollers.

And mine Opel 16V DOCH 2.0 engine, gone from 150bhp factory power, to 197bhp(comproved on dyno rollers) after my headwork, free exhaust downpipe, compressio ratio increased, alcohol like fuel and new ECU map at chip(for increase the ignition advance at higher rev, and on situations of low MEP).


I attached some pictures of 8V head ported from me. You saw that i was keep rough surface at inlet ports and i did "mirror" surface on exhaust ports. And look the low height of inlet ports guide boss..no walls for the flow. This head got the flow increased a lot of.



Cheers,


Matheus S. Almeida
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Do you have any extrapolations on what this would mean to the shorter carb manifolds I have? Will I need bigger Webers?

 

because this i was use bronze guides ever, have bigger life than iron cast guides.

And on exhaust ports at turbo engines, i don´t cut the guides, for keep the heat transfer, and other way is use sodium filled valves like my 16V engine head uses. I work with my engine on several conditions(continuos use of 7.400 to 8.300rpm) and perfect valve seal at the moment, with all guides cutted.



About the type of manifold, is not so simple to change, because the speed of flow will variates according rpm range. If you use bigger and short intakes, you will generates power at peak ranges and will kill the lower and mid ranges. The lenght of trumpet is very important too.

And a good choice is substitute de old carburetor for a fuel injection throttle bodies working with 2 injectors per cylinder(one lower injector working up to 7.500rpm, and other upper injector above trumpet working above 7.500rpm for increase the fuel mix on high speed of flow).



Cheers,


Matheus S. Almeida

 

The carb throat is nominally 40 mm(thus the name 40 DCNF) across a circle
If Vic has done some measurements, it would be interesting to know the area of the port at the head and the valves. That's what prompted if I should go to the 42DCNF or 44DCNF and taper the tract, although remember that they are choked down inside with adjustable venturi sizes of 32,34 and 36mm. The base opening of the carb is 40mm with all of the venturis though on the current 40 DCNFs. Larger engines use the 40 DCNF, although the Maserati Merak and later Urraco engines used a 42DCNF.

Looking at some old phots, you can see below that the qv port is INDEED a bit of a figure eight, while the bottom of the Capo manifolds is an oval like the 348s - this tells me that they were designed for an oval port from the outset and that I have an existing obstruction!! So for me, I need to at least port match my manifolds with my inlet port. Capo had been doing racing engines for a while, so along with others (Norwood, Kermit) this adds to the idea that the oval 348 style intake is optimal.

It looks also there is some taper to the barrels from the side from the carb, and does not widen appreciably, so I imagine they taper to the oval opening.

Please pass these along to Vic, but just at my level I imagine that the manifolds are probably close, with a definite need to open up the port to a matching oval that then tapers to the valve opening. Wonder how much horsepower is blocked by this port obstruction?

Many thanks
Russ
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please, post pictures of this engine head inlet/exhaust ports..