Some pics of installation of S3-based cam in an S4 head
06-30-2008, 08:16 PM
#46
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FWIW, yes when you fit a true spacer to the intake end plates, you are lmited by when you hit the fuel rail, etc. My plan is a little different which is to make a whole new end plate that fits tightly around the fuel rail, hence the need for my CNC. I'll start on this project once I get my heads and manifold back from the shop that did the porting / flow testing.
wrt the stock head flow, it is around 255-265 CFM at 25", .425 lift, without the intake manifold with simple velocity stack for flow intake to the port. This is a S4 head, stock valves and "normal" 3 angle valve job. No tricks...
For those interested in another opinion on the OEM manifold, it is actually ahead of its time with the flappy resonance concept. For a street car the flappy / cross resonance idea likely adds noticable bottom end torque... a good thing. The issue is how the poor flow of the runners limit the size of the engine on the top end. For pure street use on a 5.0 or 5.4 engine, I am not sure I would throw out this manifold so quickly. As Sterling mentions, there are other areas of restriction to look at.
If drivability through out the RPM range is desired, the OEM manifold is likely better than any aftermarket venture, given what a good development effort costs.
$0.02
wrt the stock head flow, it is around 255-265 CFM at 25", .425 lift, without the intake manifold with simple velocity stack for flow intake to the port. This is a S4 head, stock valves and "normal" 3 angle valve job. No tricks...
For those interested in another opinion on the OEM manifold, it is actually ahead of its time with the flappy resonance concept. For a street car the flappy / cross resonance idea likely adds noticable bottom end torque... a good thing. The issue is how the poor flow of the runners limit the size of the engine on the top end. For pure street use on a 5.0 or 5.4 engine, I am not sure I would throw out this manifold so quickly. As Sterling mentions, there are other areas of restriction to look at.
If drivability through out the RPM range is desired, the OEM manifold is likely better than any aftermarket venture, given what a good development effort costs.
$0.02
06-30-2008, 08:23 PM
#47
Its just so tempting to scrap the entire intake. Not on a cost/time scale (bad) but on a new opportunities scale.
03-27-2010, 11:58 AM
#49
Jim - any updates you'd like to share?
03-27-2010, 01:44 PM
#50
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Nothing particularly new or interesting to share... The heads, pistons and rods have all been completed. Cam profiles (one of Elgin's, of course) are known, but grinding and final heat treatment of the cam billets is another large expense.
As the completed heads can flow 15-ish percent better than the best ported stock S4 manifold runner, the use of a stock manifold casting has been dropped. Unfortunately, dropping the stock manifold adds another cost, pushing the project further out timewise until the the pot of $$$ for the project can be filled up some more.
As the completed heads can flow 15-ish percent better than the best ported stock S4 manifold runner, the use of a stock manifold casting has been dropped. Unfortunately, dropping the stock manifold adds another cost, pushing the project further out timewise until the the pot of $$$ for the project can be filled up some more.
03-27-2010, 04:09 PM
#52
As the completed heads can flow 15-ish percent better than the best ported stock S4 manifold runner, the use of a stock manifold casting has been dropped. Unfortunately, dropping the stock manifold adds another cost, pushing the project further out timewise until the the pot of $$$ for the project can be filled up some more.
How long are you thinking of making the runners?
03-27-2010, 09:17 PM
#53
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John--
Slight tangent. Maybe more than slight... What's your plan for measuring air mass flow? MAP and TPS? I'm working on a process problem, trying to get better modeling of flow through a valve at different positions. So far, measurement of flow beats calculated estimates every time. This is a steam flow/pressure/temperature problem for me, in a very dynamic process, so there's an extra dimension in my model, plus varying time of process response to various control changes. Using the butterfly throttle is extremely non-linear, and even in the rather controlled airflow environment around the throttle there's really no such thing as laminar flow within several inches of the butterfly. Anyway, can you share your thinking?
Slight tangent. Maybe more than slight... What's your plan for measuring air mass flow? MAP and TPS? I'm working on a process problem, trying to get better modeling of flow through a valve at different positions. So far, measurement of flow beats calculated estimates every time. This is a steam flow/pressure/temperature problem for me, in a very dynamic process, so there's an extra dimension in my model, plus varying time of process response to various control changes. Using the butterfly throttle is extremely non-linear, and even in the rather controlled airflow environment around the throttle there's really no such thing as laminar flow within several inches of the butterfly. Anyway, can you share your thinking?
03-28-2010, 06:34 AM
#55
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I don't want to hijack this thread, but I posted that comment, knowing that people who would appreciate this news are contributing here. I will start a new thread when I have some on car testing to report.
The application in the first instance is a stroker race car. The system in Alpha-N although I didn't know that name when I decided on the approach :-)
We wanted to retain the stock LH and EZK, but get rid of the MAF as it complicates the intake system, and can suffer from reversion pulses with more radical cams.
The main load signal is a precision (Hall effect) throttle pot. the throttle bodies are 50mm Jenvey. Air mass compensation information is derived from a MAP sensor measuring atmospheric pressure, and an intake air temperature sensor.
As there are no spare input on the LH ECU for these two additional inputs, some clever techniques are used to add them in a small "black box".
There are new maps for IAT and MAP inputs in the new LH software. New ST2 software is used. New maps for the EZK of course.
The LH and EZK remain stock. Bench testing looks OK. A mock up of the mechanical side is being done at present, prior to fitting it to the race engine. We hope to do initial testing on the car in the next 2 weeks.
The application in the first instance is a stroker race car. The system in Alpha-N although I didn't know that name when I decided on the approach :-)
We wanted to retain the stock LH and EZK, but get rid of the MAF as it complicates the intake system, and can suffer from reversion pulses with more radical cams.
The main load signal is a precision (Hall effect) throttle pot. the throttle bodies are 50mm Jenvey. Air mass compensation information is derived from a MAP sensor measuring atmospheric pressure, and an intake air temperature sensor.
As there are no spare input on the LH ECU for these two additional inputs, some clever techniques are used to add them in a small "black box".
There are new maps for IAT and MAP inputs in the new LH software. New ST2 software is used. New maps for the EZK of course.
The LH and EZK remain stock. Bench testing looks OK. A mock up of the mechanical side is being done at present, prior to fitting it to the race engine. We hope to do initial testing on the car in the next 2 weeks.
03-28-2010, 05:50 PM
#56
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Just completed the install of my "Jim Morton" modified S3 cams into my GTS.
Drove 800 miles to test them out.
Gobs of difference at the top end - not so noticable at the bottom.
Big gain on the 80 to 100 range - lots more torque.
All seat of the pants dyno but feels awesome.
Drove 800 miles to test them out.
Gobs of difference at the top end - not so noticable at the bottom.
Big gain on the 80 to 100 range - lots more torque.
All seat of the pants dyno but feels awesome.
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Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
