Street porting a 1.9 big valve head

[Tru-Craft]

Wow, great info and graphs!
So using this info my 1.9 head with street porting, cut valve guides, 1.80/1.50 valves, cam with a .459 intake lift and .435 exhaust lift, should flow about..........
Intake = 115cfm
Exhaust = 95cfm

Lyle

[RallyBob]

Originally Posted by Tru-Craft Wow, great info and graphs! So using this info my 1.9 head with street porting, cut valve guides, 1.80/1.50 valves, cam with a .459 intake lift and .435 exhaust lift, should flow about.......... Intake = 115cfm Exhaust = 95cfm Lyle

Minus valve lash!

But yes, it's a way to estimate your airflow through the head itself. However it doesn't take into account the overall reduction of intake flow from the intake manifold and carburetor, and the increase in exhaust flow from the manifold/header bolted in place.

Bob

[RallyBob]

Originally Posted by wrench459 I'm liking where your going with this! How about a custom intake with no plenum ..phased injectors using a EEC-IV V-8 ecm? Say goodbye to the heater core on a GT. Will need a special algorithm forgive me just thinking...

I think that, especially with the raised port heads, the parallel straight runners are the way to go. The center dividers are already wider than those on the low port heads, so I think the trick is fitting two GM Tuned Port throttle bodies as the center divider between the two (stock) 48 mm throttle plates matches the raised port head spacing. I planned on doing this for my Bonneville engine...short runners, big throttle plates (52 mm aftermarket), and a straight shot. There would still be an air plenum to avoid drawing warm air, and to take advantage of inertia tuning. You could also angle the manifold runners upward to match the intake port upward sweep, like I did on the sheet metal 2.2 intake I built. (pics below)

[Hiro]

Originally Posted by RallyBob Wow! Very nice work Hiro! And very fast too.... How about this latest comparison with the bare 2.4 port/Dbilas/3.0 inlet manifold? Bob

I will post these plots this evening from my home PC,
at first sight I guess your 30E modified manifold flows very well!
peak flow with the DBilas manifold fitted with ITB should be a tad lower than 134cfm (ca. 130cfm?),
that's only 7-8cfm more than the peak flow from the 30E manifold...
of course the flow path/direction is completely different,
but probably for a street 2.4 this 30E manifold is more than enough?
Hiro
ps: BTW Bob I want you in my lab!
generating such experimental data is not trivial,
this I know from my daily occupation!

[Hiro]

Originally Posted by RallyBob I think that, especially with the raised port heads, the parallel straight runners are the way to go. The center dividers are already wider than those on the low port heads, so I think the trick is fitting two GM Tuned Port throttle bodies as the center divider between the two (stock) 48 mm throttle plates matches the raised port head spacing. I planned on doing this for my Bonneville engine...short runners, big throttle plates (52 mm aftermarket), and a straight shot. There would still be an air plenum to avoid drawing warm air, and to take advantage of inertia tuning. You could also angle the manifold runners upward to match the intake port upward sweep, like I did on the sheet metal 2.2 intake I built. (pics below)

definitely the route to go for an extreme output race CIH!
I'm dreaming about this setup with a drawer-type throttle ITB...
Hiro

[RallyBob]

Originally Posted by Hiro I will post these plots this evening from my home PC, at first sight I guess your 30E modified manifold flows very well! peak flow with the DBilas manifold fitted with ITB should be a tad lower than 134cfm (ca. 130cfm?), that's only 7-8cfm more than the peak flow from the 30E manifold... of course the flow path/direction is completely different, but probably for a street 2.4 this 30E manifold is more than enough?

I agree, for a road-going engine with modest compression ratio, modest rpms, and a streetable camshaft, the 3.0 EFI intake will be just fine. The longer runners will enhance torque, while the plenum will help at higher rpms to overcome the actual flow shortcomings through inertia-tuning. Even with 'only' 130 cfm, it's still far more than a road-tuned 2.2 head with the standard 2.2 inlet manifold!

And as you said, I have not flowed the Dbilas inlets with TB's in place...this diameter will affect the total outcome. Even more would be the reduction of flow with DCOE-type carburetors in place, since the 45 mm throttle plates are not flowing 100% thanks to the main venturi diameters (usually 36-40 mm for race use).
The 3.0 EFI inlet was flowed with the 65 mm TB wired open, and when I achieved maxuimum airflow I tried to 'cheat' the air by untaping some passages I had covered up. It didn't make any difference to peak flow, so the restriction was not the 65 mm TB, but rather the intake runners themselves. Perhaps on a 'maximum effort' engine that must use this type of intake the Extrude-Honing process might make financial sense?

: BTW Bob I want you in my lab! generating such experimental data is not trivial, this I know from my daily occupation!

So how is the pay in France these days?

Bob

[Hiro]

Originally Posted by RallyBob Okay, more data gathering occurred today! I ported a street 2.4 head last week, and wanted to flow-test the bare head, as well as the Dbilas DSD intake manifolds which were port-matched to the head. Then it occured to me I had never flow-tested the cut-down 3.0 litre EFI intake I had prepared for another engine with a 2.4 head, so here was my chance to compare a ported big-valve 2.4 head (bare port), the DSD intakes, and the EFI intake on the same day, minimizing the variables. So, here are the results on the intake port with a 1.94" valve: Bare port........Dbilas intake.....EFI intake .100" - 33.5 cfm... 32 cfm... 32 cfm .150" - 50 cfm... 47.5 cfm... 46 cfm .200" - 68.5 cfm...65.5 cfm... 63.5 cfm .250" - 88 cfm... 83.5 cfm... 80 cfm .300" - 106.5 cfm... 100 cfm... 93.5 cfm .350" - 123 cfm... 115.5 cfm... 105 cfm .400" - 132 cfm... 124 cfm... 113 cfm .425" - 137 cfm... 128.5 cfm... 116.5 cfm .450" - 137 cfm... 131.5 cfm... 119 cfm .475" - 137 cfm... 134 cfm... 121.5 cfm .500" - 137 cfm... 134 cfm... 123 cfm .525" - 138 cfm... 134 cfm... 121.5 cfm .550" - 138 cfm... 134 cfm... 120 cfm Years ago I tested a ported 2.2 head, and it flowed a peak of 136 cfm through the bare intake port. I then bolted a stock 2.2 EFI intake manifold to that head, and the flow peaked at 99 cfm! I had another 2.2 intake on loan from Gil (OGTS) that had been Extrude-Honed, and it peaked at 100.5 cfm....only 1.5 cfm more! So you can see how bad the 2.2 intakes truly are... And for posterity, the cylinder #1 exhaust port with a 1.60" valve: .100" - 32 cfm .150" - 47.5 cfm .200" - 60 cfm .250" - 71 cfm .300" - 81 cm .350" - 88.5 cfm .400" - 94 cfm .425" - 96 cfm .450" - 97.5 cfm .475" - 98 cfm .500" - 99 cfm .525" - 100 cfm .550" - 100.5 cfm

so here is the plot comparing Bob's 30E manifold with DBilas' DCOE type:

[Hiro]

Originally Posted by RallyBob The 3.0 EFI inlet was flowed with the 65 mm TB wired open, and when I achieved maxuimum airflow I tried to 'cheat' the air by untaping some passages I had covered up. It didn't make any difference to peak flow, so the restriction was not the 65 mm TB, but rather the intake runners themselves.

Another clearcut demonstration Bob!
And another take-home lesson for people thinking that a monster TB will be better flowing this short 30E manifold,
Assessing the limiting factor is the key to any kind of development work.

So how is the pay in France these days?

Not too good these days,
Companies will need to fire all the old guys like me to make room for youngsters,
But young scientists in my field get far better wages & working conditions in the US or Australia so...

[Hiro]

Originally Posted by RallyBob You'll note that when modified, both the 2.2 heads and 2.4 heads both don't really start 'coming alive' until about .400" valve lift. What that means is if you are running a typical .430" lift street cam you're not letting the head make any power! A prepped 1.9 head is a better choice with low valve lift.

Yes this striked me comparing these two plots:
The ported 1.9 head improved a lot @ 0.3 low lift,
Whereas the ported 2.2 & 2.4 are not better than std @ 0.3 low lift.
This is a bad news for me,
Because I wish to increase as much as possible the mid-range torque on my race 2.5/2.7
If I understood correctly one key is increasing the flow @ low valve lift,
Any clue how to circumvent this drawback with the 2.2/2.4 heads?
Do you think carving the "flow divider fin" in the intake roof would help?
Hiro

[RallyBob]

Originally Posted by Hiro If I understood correctly one key is increasing the flow @ low valve lift, Any clue how to circumvent this drawback with the 2.2/2.4 heads? Do you think carving the "flow divider fin" in the intake roof would help? Hiro

This 'fin' was was already performed to both the 2.2 and 2.4 heads I tested.

I noticed on the vey first 2.2 head I flow tested, that if the bowls were blended, the airflow at lower lifts was worse than a standard 2.2 casting! It seems Opel had their valve angles correct for low rpm torque! In other words, if you have standard valves with the 2.2 head, you are better off leaving it 'as is' than doing any work to it!

However, with the 2.4 head and standard valves, there is some small gain to be had with bowl-blending.

I would not worry too much about the torque with the 2.7 litre engine Hiro, I think that by nature this will be it's strongest virtue! Of course you can create stronger torque by using higher compression pistons, and cams with tighter lobe separation angles, and by advancing the camshaft (earlier inlet opening). Or by playing with different length inlets and exhaust manifolds. Remember this engine is still basically a tractor engine!

What is that saying? You can't make a race car from a pig, but you can make a very fast pig...

[Hiro]

Originally Posted by RallyBob This 'fin' was was already performed to both the 2.2 and 2.4 heads I tested. I noticed on the very first 2.2 head I flow tested, that if the bowls were blended, the airflow at lower lifts was worse than a standard 2.2 casting! It seems Opel had their valve angles correct for low rpm torque! In other words, if you have standard valves with the 2.2 head, you are better off leaving it 'as is' than doing any work to it! However, with the 2.4 head and standard valves, there is some small gain to be had with bowl-blending. I would not worry too much about the torque with the 2.7 litre engine Hiro, I think that by nature this will be it's strongest virtue! Of course you can create stronger torque by using higher compression pistons, and cams with tighter lobe separation angles, and by advancing the camshaft (earlier inlet opening). Or by playing with different length inlets and exhaust manifolds. Remember this engine is still basically a tractor engine! What is that saying? You can't make a race car from a pig, but you can make a very fast pig...

Bob your street heads are much better than my so-called race heads!
The 2.2 bowl-blending data with std valve is scarry,
I remember you said numerous time that "wild porting will hurt flow instead of making it better"...
For my 2.7 race CIH I will start with basical stuffs & settings,
Head will be a ported 2.2 with 50mm intake valve,
Cam something like Dave's F328-10 or a tad bigger,
Let's see how it revs like this... without falling apart!
Hehe Pumba likes stories with fast pig/pork/hog...
Hiro

[Hiro]

this plot compares intake flows from the 1.9 competition & from the 2.2 street heads,
data are not strictly comparable because valve size is different,
but what strikes me is the extent of the linear increase zone of each head:
on the 1.9 head it's only linear uptill about 0.3" lift then it progressively bows,
whereas on the 2.2 head it's almost linear until max flow (0.5" lift) then it suddently stalls.
low port versus raised port effects?

Bob I'm very curious about how your group2 "Swedenkopf" head flows,
this head has both low & raised port features,
but IIRC the runner volume is very big so this may harm the flow by itself?
Hiro

[RallyBob]

Originally Posted by Hiro Bob I'm very curious about how your group2 "Swedenkopf" head flows, this head has both low & raised port features, but IIRC the runner volume is very big so this may harm the flow by itself? Hiro

If I recall correctly, it flowed a maximum of 120 cfm, but at very high valve lift .600"/15.24 mm. However, remember this was a completely standard casting, with standard 2.0 valves fitted (42 mm), and a bad 'lip' below each valve seat!

I *think* that this head can be prepared to flow 155+ cfm (estimated), but it will probably only be suitable for super-high rpms and monster camshafts OR very big CC displacement engines. I say this because the port volumes are so huge, there will probably be no power below 6000 rpms otherwise.

My friend Bjorn says this is true as well, the engines he has seen in Sweden with this head (2.0 litre) all have power from 6500-8500 only. Probably a very bad idea for rally or road use, but maybe good for circuit racing? Or perhaps a very big turbo...

Bob

[Hiro]

Originally Posted by RallyBob If I recall correctly, it flowed a maximum of 120 cfm, but at very high valve lift .600"/15.24 mm. However, remember this was a completely standard casting, with standard 2.0 valves fitted (42 mm), and a bad 'lip' below each valve seat! I *think* that this head can be prepared to flow 155+ cfm (estimated), but it will probably only be suitable for super-high rpms and monster camshafts OR very big CC displacement engines. I say this because the port volumes are so huge, there will probably be no power below 6000 rpms otherwise. My friend Bjorn says this is true as well, the engines he has seen in Sweden with this head (2.0 litre) all have power from 6500-8500 only. Probably a very bad idea for rally or road use, but maybe good for circuit racing? Or perhaps a very big turbo... Bob

Hehe so that's more exciting work & data to study in the future!
Wild idea: why not use this Swedenkopf with a "tall deck" 23D short block,
Maybe we can build a monster CIH4 with more than 3000cc displacement & good rod ratio,
This engine should rock!
Hiro

[RallyBob]

Originally Posted by Hiro Hehe so that's more exciting work & data to study in the future! Wild idea: why not use this Swedenkopf with a "tall deck" 23D short block, Maybe we can build a monster CIH4 with more than 3000cc displacement & good rod ratio, This engine should rock! Hiro

I have plans for this head! But because of the rarity, I don't wish to damage it doing development work. So I need to make a silicone mold of the ports, then make a plaster cast of the head. From this, I can port the plaster parts to experiment with no fear of damaging the original head! Much harder to add cast iron back!

I wish to build a roller-cammed 2346 cc engine with extra-long rods, and use a Garrett GT4094 turbocharger with this head. I want 700+ hp and 10,000+ rpms from this combination. I have a 1974 Manta that would like to try this engine out.

[Hiro]

Originally Posted by RallyBob I have plans for this head! But because of the rarity, I don't wish to damage it doing development work. So I need to make a silicone mold of the ports, then make a plaster cast of the head. From this, I can port the plaster parts to experiment with no fear of damaging the original head! Much harder to add cast iron back! I wish to build a roller-cammed 2346 cc engine with extra-long rods, and use a Garrett GT4094 turbocharger with this head. I want 700+ hp and 10,000+ rpms from this combination. I have a 1974 Manta that would like to try this engine out.

yes this head is very difficult to find,
never actually seen one myself.
whoa this turbo CIH will super-rock!
our old cast iron dinosaurs still have fun days to come!
Hiro

[RallyBob]

Originally Posted by Hiro yes this head is very difficult to find, never actually seen one myself. whoa this turbo CIH will super-rock! our old cast iron dinosaurs still have fun days to come! Hiro

I posted some pictures of one of mine a few years ago . I actually have two of them, both are new. And I have two sets of intake manifolds for them, for 50 DCO Webers.

http://www.opelgt.com/forums/opel-en...omparison.html

Bob