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Its my fault there haven't been many updates recently.
I have been trying hard to get my twinscrew supercharger kit completed. I do have an 89 with the intake removed now for completing the physical mockup testing. The upstream components (air filters, housings, intake plumbing) have all been designed and are currently being bid out. I have some plastic mockup parts here for those components, as well as the intake runners.
I hope to have some time after Thirdcoast to finalize the plenum design and get that fabricated for testing.
I will get some updated renderings posted of the plenum when I get back.
Thanks for being patient with my slow progress recently.
I wanted to follow up with you around the new intake manifold you and Hans are working on. I has a quick PM with Hans and I believe the project is to start moving again as time becomes available.
I am very keen to support the project and get my hands on a an early pre-production or prototype.
Let me know how things are progressing and if I can help in any way.
I have a vague recollection that someone has at some point tested feeding the stock S4 intake manifold from the side plates with two generously sized throttle bodies flowing a lot. What was the gain from that setup, compared to stock intake throttle body? On an otherwise stock car, my math predicts less than 8 hp but I’d like to get a reality check.
Have you seen John Gill’s ITB results? Picked up 100+ hp by dropping the S4 intake:
An otherwise sensibly tuned 928 GT 5.0 engine (11.5 compression, S3 pistons, ’87 S4 conrods, E85, Colt stage 2 cams with a too wide LSA of 114, headers, race exhaust) picked up 100+ hp in the 6000-7000 rpm range by swapping the S4 intake to 48mm AT Power individual throttle bodies with trumpets. Only intake manifold and air pickup changed. And the gap will widen if he spins it to 7500 rpm.
I agree. I think people should appreciate this result as it’s basically done without any super-trick parts (yet).
I think Dennis Kao’s engine is still the best 5.0L engine built with the stock intake manifold. This ITB engine by John Gill is probably the best 5.0L engine with the stock intake manifold ditched (am I forgetting someone?). Neither engine has anything extremely trick in it, it just all non-trick stuff works together.
Over the years, I’ve come to the conclusion that an S4 engine with the stock intake manifold retained needs to be built very differently compared to an engine in which the stock intake manifold is ditched in favor of ITBs.
The stock intake manifold engine that is looking for peak power needs to be built like a NASCAR restrictive plate engine, not like a regular four valve performance engine.
If you build the 928 engine like a regular four valve high performance engine without thinking about the limitations of the stock S4 intake manifold and then put on the stock S4 intake manifold, the results will be disappointing — but then you can uncork the engine with an ITB like John Gill did for 35% peak power gain.
I agree. I think people should appreciate this result as it’s basically done without any super-trick parts (yet). I think Dennis Kao’s engine is still the best 5.0L engine built with the stock intake manifold. Over the years, I’ve come to the conclusion that an S4 engine with the stock intake manifold retained needs to be built very differently compared to an engine in which the stock intake manifold is ditched in favor of ITBs. The stock intake manifold engine that is looking for peak power needs to be built like a NASCAR restrictive plate engine, not like a regular four valve performance engine.
Fascinating.... thank you for sharing. Could you explain more about how a NASCAR engine design maximizes output given the air restrictions? Is it all about producing loads of torque early and all the way to redline? I something else? (Excuse my ignorance, I don't know much about engine design but I am curious). Also can you share some information about how Dennis Kao's engine was set up? I am curious as I expand my learning from repairs to modifications.
__________________
George
90 S4 Grand Prix White (Murf #5 - 219.0 mph top speed)
94 GTS 5-Speed Midnight Blue
06 Cayenne S Havanna/Sand Beige (PASM) http://928.jorj7.com
I agree. I think people should appreciate this result as it’s basically done without any super-trick parts (yet).
I think Dennis Kao’s engine is still the best 5.0L engine built with the stock intake manifold. This ITB engine by John Gill is probably the best 5.0L engine with the stock intake manifold ditched (am I forgetting someone?). Neither engine has anything extremely trick in it, it just all non-trick stuff works together.
Over the years, I’ve come to the conclusion that an S4 engine with the stock intake manifold retained needs to be built very differently compared to an engine in which the stock intake manifold is ditched in favor of ITBs.
The stock intake manifold engine that is looking for peak power needs to be built like a NASCAR restrictive plate engine, not like a regular four valve performance engine.
If you build the 928 engine like a regular four valve high performance engine without thinking about the limitations of the stock S4 intake manifold and then put on the stock S4 intake manifold, the results will be disappointing — but then you can uncork the engine with an ITB like John Gill did for 35% peak power gain.
Very interesting to see. I am as much interested in the mid range power as the peak. Any ideas on whether the midrange can be boosted with mapping as it looks down on stock?
Very interesting to see. I am as much interested in the mid range power as the peak. Any ideas on whether the midrange can be boosted with mapping as it looks down on stock?
I assume that the engine is mapped about right, given that the car owner also owns a dyno.
It's a race car shifted at the redline so what matters is the average power between the shift point rpms. Below those rpms, the torque really only matters for a standing start.
I think that the midrange could be boosted for this engine by making the intake trumpets longer. They would have to be packaged in a cross-ram configuration to fit under the stock hood, which takes some effort but only requires gentle bends that don't interfere with power production. The effort mostly comes from the fact that the trumpets will have to cross at a point where they are already expanding in cross-sectional size.
Another, complementary way to do that would be to grind a new set of cams with about the same duration and lift but much more overlap. For an ITB race car, maybe move the current LSA of 114 to something like 106, my guess is as good as yours?
In any case, John Gill can comment more on his car.
11-03-2016, 09:39 AM
