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Richard Jemison
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Discussion Starter · #1 ·
Here is some info regarding HP from a well maintained Verde engine, and effects of head porting on a 2.5 V6. And the same 3.0 Verde engine with simple mods and cams.
The Dyno sheet on the 3.0 shows HP both before rebuild and after using Factory FI (unmodified in any way), and after the conversion is done I will post the Dyno results using Megasquirt.

This is a car that was and will be daily driven and driven to the track for various track day events and has been previously maintained in Peter Krause`s shop, so it was in good order prior to this testing and build. However the engine is a stock Verde with only headers and downpipes with stock exhaust, (not open), with "S" cams.

The rebuild was done by Al Mitchell for the owner, using components I built and assembled. The Dyno is Al`s personal dyno, that is very conservative, requiring about 10-12% upward adjustment to equate data from commercial Dynos(Mustang etc) Just FYI..

Mods:
I flycut the "S" pistons for more valve relief to the sides and .020 deeper on the intake to clear intake valve.
I cleaned up the heads doing my typical valve reshaping (stock size valves) and enlarging the seat openings to max. Bowl and runners reshaped and the curves straightened for flow. Guides shortened. Head milled and RJR796/82 cams fitted. These are hot street cams, not race cams. Profiles for both lobes are on my website. (This exact set of cams was tested in Al Mitchell`s 2.5 liter (10.5 to one) race motor with Megasquirt FI and made over 205HP at the rear wheels on this dyno. a bit less than the RJR race cams made in both ported and unported heads)

The compression with head mods and cut pistons is est about 10.25 to one.

The initial pre-disasembly run on the dyno (3rd sheet bottom) indicates about what you expect from a good V6 3 liter Verde engine, with factory injectors, stock fuel pressure regulator etc, but better exhaust (headers). Note rev-limiter cut-off.
This FI system is adequate for the 3.0 with "S" cams but with the improved heads & cams was running lean and killed the higher (5000RPM up) output and did not allow full RPM range of cam`s/head`s capability due to rev limiter and injector limits on fuel delivery.
I will post the Dyno info after Megasquirt is done.

The 1st two dyno sheets below are of a race 2.5 (10.5 to 1 compression limited by rules) showing HP/Tq before and after with the same race cams on properly (RJR) ported heads. Unported heads were very well done by shop in S.C.
 

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What is the cam´s lift?

I have "s" pistons and C&B cams without any piston mod. (3.0 engine...)

Anyway my car seems to feel underpowered after about 5500rpms... stock gtv6 2.5 ignition and intake runners and megasquirt for fueling... next to do is take care of ignition and see if it performs better in high rpms, then big runners and big exhaust (csc headers only now)

Do you have a clue of what´s going wrong to feel the lack of power? AFR is ok (stock injectors whith more fuel presure, about 10% more fueling)

I feel the lack of power under acceleration in fifth gear, the car goes fine till 180kph but then the acceleration is much slower.
 

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Luis,

They should be a little bit more than 11mm. These are something like C&B Stradale Medio but superior ramp design and you get to decide the lobe centers (LC). If you have no emission inspection, go with the most aggressive LC. Then get the max compression you can get from the engine and fuel quality (my guess is around 11:1?).

BTW doesn't your car already have CSCs?


RJ,

What is your opinion on long tube headers? I believe you said your ex-GT2 car ran on factory cast iron headers? Was that due to regulations?
 

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Richard this is very interesting for me because my 3.0 litre Potenziata engine has had pretty much the same rebuild and head mods. It has "S" cams and pistons and the heads have been milled twice. This engine is of course running Motronic which has a rev limit of 6,700rpm and also has the higher pressure fuel regulator (4 atm instead of 3 atm that the normal 3 litres have). I run 98 octane Australian fuel. Do you think my HP would be around the same or a bit more?
 

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Luis,

They should be a little bit more than 11mm. These are something like C&B Stradale Medio but superior ramp design and you get to decide the lobe centers (LC). If you have no emission inspection, go with the most aggressive LC. Then get the max compression you can get from the engine and fuel quality (my guess is around 11:1?).

BTW doesn't your car already have CSCs?


RJ,

What is your opinion on long tube headers? I believe you said your ex-GT2 car ran on factory cast iron headers? Was that due to regulations?
My car have CSCs, but only headers, i want to go to SV specs, now they have the smal diameter to fit the stock exhaust:



And maybe this is the next crazy step:



Inspections are not a problem here whith old cars that never comes with CAT.
 

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Richard Jemison
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Discussion Starter · #6 · (Edited)
Output etc:

Oz: The stock head was well done regarding valve shape and seat opening although not ported. I suspect you would be lucky yto make that power. Not something to guess and prognosticate, and not worth the time to think about it...
Zamani; The GT2 car had long primary tube headers I designed and built with two separate exhaust exiting through the passenger door (which was aluminum and dzus fastened to car) so hardly replicable for normal use. The GTR has cast iron headers modified with tubing down pipes and far less congested as bottom of iron headers is cut off and ported internally, right at junction of the 3 tubes. See pic

If I can find a pic of the GT2 headers, I will post, but not likely.

Most data supports the limit of the stock FI components to about 200 HP (flywheel) using a bit more pressure but Fuel flow from these injectors is the limit. Best swap seems to be Bosch blue top version.

Luis: Big runners will only hurt. I posted full profile of those C&B cams here in the BB somewhere. Zamani (Evo75 might know where... it was his pull-outs I ran through the camdoctor to measure. From memory not much more intake lobe than "S" and stock exhaust and large LSAs to insure fit with no issues. (114/114 LCs (114LSA)). In comparison, The RJR cams in this motor had 107 LSA and set to 105/108 LCs using my adj. sprockets. The same cams with 110 LSAs would have fit with no extra cut out of intake valve relief in the pistons. The issue with off the shelf cams is the LCs are done that way to keep installation fool proof, which kills the performance cams can give if properly designed. Cams built for a specific application, designed to fit a particular engines build will produce far better results.
The profiles of the RJR796 is on my website as is all the factory Alfa V6 12v cams.
But here it is with the intake lobe of the C&B ARM6SM1 cam profile. The C&B exhaust is same as all stock V6.
Cam 796 Lift & Duration / C&B / "S"
Lift Duration
.020 280 292 287
.050 256 232 233
.100 231 212 208
.200 189 172 165
.300 141 124 114
.400 72 38
.436 Max . Lift .408 .398
 

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Luis: Big runners will only hurt.
Richard, do you mean in this specific case, or in general.

Didn't Alfa go to bigger runners on the 164S? I think they were about 38mm id, vs just under 35mm for the GTV6/Milano runners. Also I am pretty sure the South African crowd runs big runners, and Jim K's results show big runners help a lot.

Of course we know on the 24 valver Alfa went up to 44mm, sure that's a 24 valver, but that engine is pretty close in power to a super hot 12 valve 3.0.

Greg

I
 

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Richard Jemison
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Discussion Starter · #8 · (Edited)
Runners

Runner diameter and length is the determining factor in charge timing and where it effects the power curve. The longer 164 runners are to make torque, and different sizes based on where that improvement is wanted. With GTV6/Milano runners smoothing and no more than 36mm seems to be optimal for length and usable engine RPM (3500-7000).
Why tune for higher? Motor won`t live at higher RPM long. Make usable Torque & HP in normal use range.
The shorter Milano/GTV6 runners are best overall.
The other factor with Runner length/diameter is camshaft lobe separation angles. Shorter runners work well with closer LSAs (105-108), and longer runners typically work better with wider LSAs, both of which (Longer runners/wider LSAs) are typically used to move the torque curve lower.

High HP No.s are not the target, wide usable torque curves make fast easy to drive cars.

Look at Al Mitchell`s torque curves on the 2.5 V6. Even with the RJR 243/82=3(6) big race cams he does not have a "peaky motor" and HP is still at 1HP/CC at the flywheel. (still with only 10.5 to one and stock valve sizes!):p
 

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High HP No.s are not the target, wide usable torque curves make fast easy to drive cars.
I agree. One of the great things about the 3 litre V6 12 valve is that lovely flat torque curve and flexibility. It makes them such fun to drive. Mine still has that quality, only stronger with the head work. What's more the fuel economy has improved in the process. I am getting 27 mpg (imperial) around town and the other day I got 33.9 mpg on a 524 km run on the open road to to the south of our state at 110kph with a passenger and a load of camping gear. With our speed limits and yours in the US I suspect, high end power production is not very useable. On a European Autobahn it might be.
 

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Richard, you are probably right, but I just don't see it yet.

I understand that runner length is also a factor, but still, if the 34-35mm stock runner was the right size for a stock 2.5, it seems to me it has to be too small for a worked 3.0. Virtually every other serious Alfa V6 builder I have talked to or corresponded with says these cars need bigger runners, even within the RPM range we are talking about. This included Mike Sperry and Jim K.

I am going to look into this further, because this is one of the few areas I thought all the builders of hot N.A. 12 valvers were in agreement on. I guess it isn't!

Greg
 

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Richard Jemison
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Discussion Starter · #11 · (Edited)
Runners

Somewhere in the past, perhaps it was Shankle, built and sold large diameter runners for these cars. They killed all but very high rpm power. A couple of Alfa racers have them boxed away after noting the same loss of drivability.

Unfortunately "bling" like big valves with small stems, large runners attract attention and sells books:rolleyes: but as to adding performance it is a waste of $$ and only adds issues. Where is any HP they are making? All at high RPM...I see JK`s pics of valves/pistons and I know it is only marketing. Wish the typical Alfa owner understood that. I prefer performance, not the "I`ve got this & that, bragidosio" in my motor mentality.
 

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Anyway, the intake diameter in the head is bigger than the runners diameter, why not oversize the runners to the head diameter?
 

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I ported my runners, around 37-38mm. Good enough for a 12V.
 

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Anyway, the intake diameter in the head is bigger than the runners diameter, why not oversize the runners to the head diameter?
Why not indeed? That's the heart of my question.

I ported my runners, around 37-38mm. Good enough for a 12V.
So, did it make more power or cause any loss at the low end?


In defense of Jim, I really don't think he is making money by writing a book on the Alfa V6, it's a very limited market and he spent a fortune buying and testing different things. He certainly doesn't sell BMW valves, head porting services or other things he describes in his book.

That said, it's very impressive Richard is getting tremendous results from what are essentially stock parts. Obviously that says a lot about his cams and porting knowledge.

Greg
 

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Weren't the shankle runners like 50mm at the inlet and like 45 mm at the head? That is way to big for a 3.0.

I think the conventional rule of thumb for intake runner diameter is like 85% to 90% of the intake valve diameter. So 37 to 40 mm for a 3.0L.

Stock runners ar 34mm, Richard is saying 36mm, Jim K. Says 38mm-39mm.

I think everybody agrees pretty closely and staying on the small side (like Richard says) would improve torque at lower rpm.

Jeff
 

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Greg,

I don't know about power, but Beninca said do it, Jim K said do it too. And the 164 runner is bigger, so my guess was the stock ones are just too small.

I dynoed all modifications at once, so I can't say for sure if it made power just due to the runners.

But the last time I dynoed the car with the RJR cams the engine was making power all the way up to 6900 rpm. You don't usually see that with the usual S-cams and S-pistons setup.

Another point, I agree with you Jim K won't get anything out of his effort. He is just doing it out of his love for the hobby.
 

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Stock runners ar 34mm, Richard is saying 36mm, Jim K. Says 38mm-39mm.

I think everybody agrees pretty closely and staying on the small side (like Richard says) would improve torque at lower rpm.

Jeff
I guess it depends on what you mean by "on the small size" 38mm is quite a bit larger than stock, it's about 21% more volume.

Greg
 

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Greg,

I meant if the intake port diameter is on the small side of the normal rule of thumb (per my previous post) then it would be better for low end torque. I'm sure that a stock 34mm port is even better than a 36mm or 37mm port for low end torque but it probably hurts high end power.

Jeff
 

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Richard Jemison
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Discussion Starter · #19 · (Edited)
Runners

I don`t care what anybody thinks or believes. I`ll continue doing them my way, to the delight of customers. Not selling books, or "bling"...
As my 5th ex-wife was continually saying:

Whatever:rolleyes:
 

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Hey Richard,

Did you ever get your 3.0 finished with the 796/61 cams? If so how did you like it? How do torque and power compare with a longer duration exhaust like Al M.'s 796/82? My motor is still on the stand, no time lately....:mad:

Thanks,

Jeff
 
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