Dan From Sault Ste Marie Ontario

[Indycars]

I was curious how much difference changing only the cylinder head from OEM to AFR 205 would
make. So I used Sim01, changed the heads and nothing else. Below is that comparison graph.

Do you have the part number ? AFR typically has a street version and a competition version, which head
are you using ? This will help me keep my documentation of my library head flow valid, thanks !




Then I made the rest of the requested changes shown below on the Highlighted lines. This new simulation will be called Sim05.



Below is the new graph for Sim05 with all the changes compared to Sim01.



Daniel, I see where you are showing a DCR of 8.3 after the changes made above, I get 7.75. Assuming that you
wanted more low rpm torque, I advanced the came 2° and 4°, which shows a DCR of 7.91 and 8.07. Either one
of these have a decent chance of working with a 91-octane fuel.

The RED characters denote a change from the previous engine calculations.



With the camshaft numbers provided by Summit, Dynomation was able to calculate the IVC of 79°. Now
I’ve never used the “Rocker Math Calculator” RMC on any forum before, but when you changed from
Rocker Ratio RR of 1.7 to 1.8 the event timing number changed slightly. Changes are noted in the
graphic below. This is why you see in the Excel calculator an IVC of “79.3°”. The duration of the intake
valve increased by 0.6° total . You will want to review my numbers and let me know if you see something.

 

[Grumpy]

when most people look at a dyno sheet like this (posted below ) they may get the totally erroneous idea from the graph,
that they will lose a significant amount of lower rpm torque as the dyno graph tends to show,
but thats a fallacy, you don,t drive a car looking at the tachometer in low rpm driving you simply depress the throttle when you want to accelerate,
think about how you actually drive.... you give the car a bit of throttle and you move the car,
it takes about 30-35 hp to keep a car traveling at a steady 60 mph,
if you want to accelerate you depress the throttle and the car response is increased speed,
with most drivers, if you place a horizontal line between the two torque curves ,on the graph,
you'll notice about a 150 rpm difference in any torque value,
youll never notice that while driving.
if the cars drive train gearing matches the engines power band, you cruise around at about 1400-1800 rpm,
you quickly learn that its effortless to spin the rear tires on dry pavement,
and you learn from experience and engine sound to manually shift to the next gear at about 2500rpm-3500 rpm,
or the auto transmission will do it for you under part-throttle acceleration,
in normal driving,
if you had a chance to drive the car with either engine you would subconsciously,
adapt your driving style to match the car characteristics and,
I doubt seriously that you would notice any difference under a daily commute,
but you would darn sure notice if you were trying to race or max out the cars performance.
where that huge gain in peak power generated on sim 5 would be obvious,
but in daily low speed driving its just not obvious.
I drove a 496 BBC corvette for a few years that made almost 700 hp at peak rpms,
under most driving conditions on the street I doubt I exceed 3500 rpm.

 

[Indycars]

you cruise around at about 1400-1800 rpm, you quickly learn that its effortless to spin the rear tires on dry pavement,

you would darn sure notice if you were trying to race or max out the cars performance where that huge gain in peak power generated would be obvious

True, maximum acceleration will happen if the tires are able to resist spinning. Therefore more
torque in the RPM band and gear ratio multiplication area where the vehicle already has enough torque
to spin the tires will only server to spin the tires even easier not go faster.

 

[Indycars]

.
I would like to introduce another feature of Dynomation I’ve never posted about before, it’s called
the Pro Iterator. It allows me to specify within a range the valve timing. It has a single phase and
dual phase, dual phase take what it learned in the phase 1 for the seed used by the 2nd phase. From
the settings noted in the graphic below, Dynomation will run 625 simulation for phase one and
another 6561 simulations for phase two, for a total of 7186 simulations.



Also I can specify two more significant parameters. What I want the Interator to maximize and
within a specific RPM range. I choose to maximize the AREA under the torque curve from 3000 rpm
to 5500 rpm. Graphic below will note my selections.

You will notice in the lower left corner the results. The Interator increased the AREA units below
the torque curve by 69.6, for an increase of 6.3%.



Below is the graph showing the result of the Pro Interator compared to Sim01 and Sim05.



Cam changes made by the Pro Iterator below.



.

 

[JohnHancock]

Do I read that right? Changing heads made almost 100 hp?

 

[Grumpy]

that 70-80 hp gain from a cylinder head swap is not exactly RARE when swapping from a rather restrictive OEM cylinder head ,
to one of the better aftermarket cylinder heads, so yeah, not an un-common result

 

[Indycars]

HP = Torque x RPM

If you consider the formula above, any time RPM is increasing and torque is constant ..... HP will
continue to increase. The nearly 100 HP you have noticed has happened because the heads continue
to flow more as RPM has continued to increase above the usable range of the stock heads while also
increasing torque at the same time.

 

[Daniel Westerbaan]

OK, first I am very happy to see the curve for the improved heads.
Second, a big thanks to Grumpy for this site because I would have never been able to learn how to evaluate the valve train and cylinder head port sizes without it.

Third I will answer some of Rick's questions:

Do you have the part number ? AFR typically has a street version and a competition version, which head
are you using ? This will help me keep my documentation of my library head flow valid, thanks !

I was looking at the AFR mongoose LS1 cylinder heads.
AFR PART #: 1510 https://www.airflowresearch.com/205cc-ls1-cylinder-head/ & I would get the sping upgrade to support the .650 lift
There is an interesting LS cylinder head comparison I found online, these AFR heads seemed to flow a lot closer to advertised on the comparison (but I take it with a grain of salt as it was done by AFR). https://ls1tech.com/forums/generati...317323-interesting-flow-data-long-thread.html

You will want to review my numbers and let me know if you see something

The numbers look correct to me based on the CAM specs. However, I don't have a way to calculate and double check how the 1.8 rocker would increase the duration.

I see where you are showing a DCR of 8.3 after the changes made above, I get 7.75. Assuming that you
wanted more low rpm torque, I advanced the came 2° and 4°, which shows a DCR of 7.91 and 8.07

Yes, I will always want more torque
I have never been clear as to *when exactly* to calculate DCR, so I do it from from 3 calculations:

1. I calculate the intake valve closing event from the cam card at 0.050" + 25 degrees. This gives me the intake valve closing at 73 degrees ABDC. This gave me a DCR of 8.3
2. I calculate the intake valve closing event from (0.5 X Advertised Duration) + LSA - 180. This gives me the intake valve closing at 79 ABDC. This gave me a DCR of 7.8
3. I calculate the intake valve closing event from the 0.006" closing event on the cam card. I did not have this value for the 8702 camshaft.

Now my calculations do not account for the volume between the ring land and the pistons. (but I will build that in soon!). So that would explain the slight differences. I take it the simulation software calculates it closer to the 2nd method and our difference in DCR comes from the volume in the ring land to piston ring.

I was curious how much difference changing only the cylinder head from OEM to AFR 205 would
make. So I used Sim01, changed the heads and nothing else. Below is that comparison graph.

Fourth: Rick, can you answer a question for me?
Can you confirm that when you ran the head comparison you changed the combustion chamber volume as well? I am doubtful that the curve has so much torque when the advertised duration (my method 2) returns a DCR of 7.53, (your simulation would calculate slightly less due to the piston ring to piston top volume) But hey if that works why not just put on the AFRs and enjoy buying cheaper fuel?

 

[Indycars]

I was looking at the AFR mongoose LS1 cylinder heads.
AFR PART #: 1510

Thanks , with this info I can label my Head Flow File appropriately so I don't have to recreate
the wheel next time the next person used the same head.

The numbers look correct to me based on the CAM specs. However, I don't have a way to calculate and double check how the 1.8 rocker would increase the duration.

The increase to 1.8 rockers is not something I would be concerned about, 0.6° is not enough in
a simulation to worry about.

I have never been clear as to *when exactly* to calculate DCR, so I do it from from 3 calculations:

1. I calculate the intake valve closing event from the cam card at 0.050" + 25 degrees. This gives me the intake valve closing at 73 degrees ABDC. This gave me a DCR of 8.3
2. I calculate the intake valve closing event from (0.5 X Advertised Duration) + LSA - 180. This gives me the intake valve closing at 79 ABDC. This gave me a DCR of 7.8
3. I calculate the intake valve closing event from the 0.006" closing event on the cam card. I did not have this value for the 8702 camshaft.

Number 3 and number 2, are basically the same thing. With the right info you can calculate
IVC on the seat. But Number 1 is just an estimate and can be off by a significant amount. You
can see how just difference just 4° makes. Some people use the .050" timing number plus
15°, you used 25°, this gets you a rough estimate only.

Now my calculations do not account for the volume between the ring land and the pistons. (but I will build that in soon!). So that would explain the slight differences. I take it the simulation software calculates it closer to the 2nd method and our difference in DCR comes from the volume in the ring land to piston ring.

It's a small volume, but it is part of the calculations if your into an exact number. My Excel file
used above takes this volume into account if you want to download it. It's available in the
"Spread Sheets and Engine Related Forms" section.

Can you confirm that when you ran the head comparison you changed the combustion chamber volume as well?

I went back and reloaded Sim01 and then made all the changes required by the new AFR 205
which includes the following:
Port Flow Rates
Larger Valves
Combustion Chamber Size
Piston Valve Reliefs
SCR = 11.05

The larger Summit 8702 cam didn't exceed 8707 until you get above 5200 RPM.



When I added the new RR of 1.8 to Sim01b, there was zero difference. The two curves
were directly on top of each other.

What else would like to see ???
.

 

[Daniel Westerbaan]

What else would like to see

Well I am following the camshaft selection advice where you go and contact as many cam manufacturer's and see what they say.
The summit 8707 was one of them. I will wait for Howards to send me the cam card and I think it would be interesting to see the comparison of the 5 cams.

However, I take it your integrator has already told me the ideal camshaft to order (and I could with a custom grind if I wished to pay for it).

I think the build is pretty locked down and I should focus on finalizing the valve train, make a parts list to review. Then order the bottom end and heads, cc and measure everything and then validate the camshaft selection at the end to match the true dimensions and not just the advertised ones.

 

[Daniel Westerbaan]

When I added the new RR of 1.8 to Sim01b, there was zero difference

Does this mean there was 0 difference for the sum 8702 as well?

 

[Indycars]

Does this mean there was 0 difference for the sum 8702 as well?

No I can't say that, didn't try that comparison on the Summit 8702.

 

[Indycars]

While waiting on the shade to develop in front of the garage door, I did some more playing.



Cam Specs from the Dynomation Sim01b + Iterator Below:




This looks alot more reasonable to me for the street since the overlap dropped from 94.5° in
Sim05+Iterator to 66.5° for Sim01b+Iterator.
.

 

[Daniel Westerbaan]

Does any one have experience getting cam cards from Howards cams? I cannot find them at all. I even asked the tech support but have not heard anything back

 

[Indycars]

Some companies don't make it easy. If you know the PN or Grind #, then you might do a search on
it, sometimes I've found them in other forums.

 

[Daniel Westerbaan]

Ok, so I think it is safe to assume I will not hear back from Howards Cams.
Here is the camshaft info I have. I have also calculated the average at the bottom. See attached

 

[Indycars]

Did you want me to run another sim, which cams or all ?

I can't find where Crane has a part number 1449351 is this correct ? Well I can find it on other websites,
but not on the Crane website, not even in their 244 page pdf catalog.

Do you have a part number for CamMotion ?

The CompCams Thumpr series are known to about the idle sound and not so much about having
the best performance.

 

[Daniel Westerbaan]

Here is the cam card that crane sent me. I don't have a part number from cam motiong, but all the details sent are in the pdf.

 

[Daniel Westerbaan]

Did you want me to run another sim, which cams or all ?

If it isn't too much to ask it would be nice to compare them all.

 

[Daniel Westerbaan]

CompCams Thumpr series

Yeah, I was a little dissapointed to see it recommended