308 QV head porting

I'm finally rolling on the heads. Here are some baseline number for the intake side. They are at 10 inH2O vacuum. Notice my blower intake with the intercooler in it flows almost exactly the same as a stock intake...and both intakes cost about 7%

The flow came up 5% with a few touches of the grinder and a bit of clay....I'm expecting it to be up 40%+ before it's all said and done
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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

 

There are a few things of interest...at least to me.

The head flow continues to go up with valve lift to over .500" lift...in theory the valve should be fully exposed at about .300 lift (which is why the factory picked that number). When the port is fixed, I don't expect to see that as pronounced as it is now. (there is no doubt I'll be needing the buy the 328 cams from you).

another note is that above .300 lift the factory manifold falls steadily behind my intake, but the runners are basically the same. I think that is probably the throttlebody...Kermit may have had that right.

Both intakes are pretty restrictive....we all need webers or individual throttlebodies....but I need an manifold, I 'll have to think about that.

Velocity is just the flow/cross sectional area at the point of interest. Right now, the area has not been altered anywhere, so the 5% flow increase is a 5% velocity increase as well....it would be a 15% increase if I switched to individual throttlebodies.

 

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.

 

Air flow is the single biggest contributor to making hp. Compression ratio matters some, internal friction matters some, but air flow is 90% of it. Cam timing affects air flow, say 20%, the remaining 80% are the flow passages…ports and manifold runners. Mass production engineering is done in hp/$ and hp/lb…paying someone to message the ports to make them perfect doesn’t fit well in the production model.

A 3.0 liter 8 cylinder engine spinning to 7700 rpm needs the intake to flow about 130 cfm at 10”H2O vacuum, but the stock set-up only flows 88 cfm. That is the reason the engine makes 80 hp/liter instead of 100+ like it should. Porting will fix that provided the factory didn’t design ports that are beyond hope…actually any port can be fixed, but when you have to start welding the snot out or it or boring the whole thing out to the back of the valve seat and welding in a whole new port, it just stops being worth the effort except in some racing applications (like the 80s air cooled 750 ducati).

As far as porting being an old hot-rodders trick, it is. Porting has been around a long time, but the how to do it keeps changing and improving. For years a triple angle valve job was the first step because the angle smoothed flow around the seat and could yield a 5% improvement, blending the seats was hot. Both are pretty much a sure thing to work and 308 QV heads come that way. Beyond that, a flow bench is pretty much mandatory because what looks right often isn’t right. On most engines a 5 angle valve job works better and a radius cut seat is even better, often with different radii above and below the seat…but not always. You need a flow bench.

I’ll post the flow numbers, how much Vic gets to do the work, and what my gains are, then anyone thinking about doing it can make an informed decision. I’m pretty confident that the gains will be worth the trouble. I think a QV fitted with EFI and ported heads should be making about 330 hp for around $6k in parts. That’s more hp than a 348 for well under the cost of moving to a 348. You get other things when you buy a newer car, but personally I like my old car.

 

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.

 

He told me that too. He said he used a 348 intake gasket as a template. I think he was probably basically right there too. I don't reall like the idea of just opening up the port though, that will decrease velocity. Then it's a math game...does the flow go up enough to compensate for the increased area and keep the velocity at at stock numbers or above?? We'll see.

My first though looing at the port is to epoxy in the bottom part of the "8" and grind out the top part. That makes an oval with about the same cross-sectional area as stock. The oval should be better then the "8" because it's got less perimeter distance per section which should reduce flow losses....again, we'll see.

I'm not sure it's a good idea to think about milling the heads...I don't think the gain wold be worht the the risk to the heads. Pull that engine out

 

Vic was been crazy busy too from what I understand. I'm sure there is a LOT to be had porting the 2v heads. Norwood she they do a job just by hand that is good for 10%....I'm thinking there is a lot more than that to be had. I know Nick must be flowing at least 120@ 10" h2o through his heads to make the hp he does, but I don't know what he charges to do it.

 

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

 

I don't know....it's my understanding they are the same as the 308 QV. I'm sure there is plenty to gain. We'll see for sure if Russ decides to do his.

 

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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Cutting the guides always scares me...good for flow, but not the best for supporting the vavle or getting heat out.

 

Spent some time on the phone with Vic tonight. He doesn't thing I built enough taper into the runners on my intake....which I knew.....The magic number is 4 degrees of taper, but I use 2 because it fit nicely and it was about 2 degrees more that stock. I may need some more volume up top to help with the 90 turn coming out of the intercooler. I see some cutting welding in my near future.

This has some implications for the OEM FI intake too....there isn't enough taper in the runners and not enough metal to grind them to far enough. This could be why the felling is porting the heads doesn't add much...because as soon as the heads flow, the intake doesn't and there is no real hp improvement. The manifold can probably be made better, but really make power, the best place for the OEM intake is ebay.

I'll keep you posted.

 

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

 

I don't know.....do you know bore of you carbs? (where they meet the intake)
I was eally thinking about the FI intakes...but now that you mension it, the carb intake runners don't have a lot of taper either. Without the 90 degree turn at the top it may be less of a problem for you, but that way the system should look is like a 355/360,nice and straight and tapered from the top right down to the valve.

 

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..

 

Just a quick update.

It looks like 11% gain is where the head comes out with stock 29mm intake valves. The 348 intakes are 30.5mm but Vic is thinking I want to be at 31-32mm to make the numbers the engine should be making....so 31-32mm it is. We're searching to see if there is anything off-the-shelf that will work or is I need to order custom valves (which are still cheaper than OEM ferrari I think).

I also started the new intake. I'll post some pics when it starts to look like more than a pile of tubes.