Stan Weiss wrote: ↑Tue Aug 20, 2019 11:14 am
Remember it is not only about how much air and fuel you can get into the engine, but also about how efficiently the engine uses that air and fuel.
For sure, hence my comment about trapped ve & combustion efficiency. Restricted class engines really highlight the importance of using the air well, it's really quite amazing how much more power you can make with the same amount of air by honing in on trapping as much of it as possible & burning it as nicely as possible.
When you start factoring in reducing friction & windage losses, improving seal etc with thin rings, gas porting, crankcase vac etc you can have 2 engines consuming the same amount of air but producing very different power. A basic 600hp engine with home & garden parts & pump fuel can become a 700hp engine consuming the same amount of air. At a cost of course, both in $ & in longevity & maintenance.
levisnteeshirt wrote: ↑Wed Aug 14, 2019 11:44 pm
Grumpys and Smokeys books talk about 600hp level 350s ,, late 70s stuff ,, doesn't look difficult ,, Smokeys stock block Indy motor was 675 with a roller cam and mechanical FI , 355 ,, nothing really out there
Jenkins did it but he had a team of pros sweated every detail spent countless hours on porting the old 292 heads,welding and porting on the prostock versions and he only managed 500 to 550 in cup trim.I wish it was that easy for example I have a 355 with 11.5 to1 comp solid roller cam and a set of reed ported 292"s and according to my calcs based on et and mph shes only putting out about 450.The heads were state of the art in the early80's cost the original owner about 3000 in early 80's bucks.
Does yours have an 850 on it ? 270/280@050 106 solid roller ? 13-1 ?
I cc'ed the runner I have been messing with last night, it is a little over 190 cc's which better explains the high air speed.
I have not done any more work on the port yet but it was good to know I still have plenty of room to work with.
Here is a rough idea with my cut away of where I am at with intake to head transition.
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How does the engine know where the intake ends and the head starts?
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GARY C wrote: ↑Tue Aug 27, 2019 12:59 am
How does the engine know where the intake ends and the head starts?
It's not supposed to, is it?
No in theory it would be one single intake port but looking at different dyno test it doesn't always seem that way, for example on EMC tv they test 3 sets of AFR heads on a 400" SBF and the 165cc and 220cc heads were virtually identical from 2500 to 6000 but the 195 head was up 6 ft lbs an 13 hp at peak and up through out the entire curve.
Just pondering.
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KnightEngines wrote: ↑Sat Aug 17, 2019 8:59 pm
Gary, open the valve till its flowing 280cfm, probe at that lift.
Fast is good, just not too fast.
I played with that some, went from 397fps to 379 still over 400 at the st, tried the intake and went from a peak of 308 cfm to around 296 but port speed was virtually the same.
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Is it stable out to .100" past peak lift?
If it is I reckon you're done, biggest problem with 400+ ft/s over the turn is stability, usually above 400 you'll have trouble keeping the flow attached, but if it's stable, sounds good & does not back up till at least .100 past peak lift you're ok.
I've had C3's through that were 430ft/s over the turn but dead stable, they make 645hp on a 5L engine.
KnightEngines wrote: ↑Tue Sep 03, 2019 1:04 am
Is it stable out to .100" past peak lift?
If it is I reckon you're done, biggest problem with 400+ ft/s over the turn is stability, usually above 400 you'll have trouble keeping the flow attached, but if it's stable, sounds good & does not back up till at least .100 past peak lift you're ok.
I've had C3's through that were 430ft/s over the turn but dead stable, they make 645hp on a 5L engine.
It's around 288 @ .500, 306 @ .600, 308 @ .700 and beyond. 2" at the opening and 1.95ish at the pinch.
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GARY C wrote: ↑Tue Aug 27, 2019 12:59 am
How does the engine know where the intake ends and the head starts?
It's not supposed to, is it?
No in theory it would be one single intake port but looking at different dyno test it doesn't always seem that way, for example on EMC tv they test 3 sets of AFR heads on a 400" SBF and the 165cc and 220cc heads were virtually identical from 2500 to 6000 but the 195 head was up 6 ft lbs an 13 hp at peak and up through out the entire curve.
Just pondering.
probably because up to the point of the 195 the minimum cross section was in the head, and after that the minimum cross section was in that tiny POS intake they used for the test. how could they have not known that would skew the results. that test was a joke.
"Anyone who thinks the low RPM engine will be faster just does not have as much experience as the rest of us" -The late, great Joe Sherman.
You wont beat anyone if you do everything the same as everyone.
No in theory it would be one single intake port but looking at different dyno test it doesn't always seem that way, for example on EMC tv they test 3 sets of AFR heads on a 400" SBF and the 165cc and 220cc heads were virtually identical from 2500 to 6000 but the 195 head was up 6 ft lbs an 13 hp at peak and up through out the entire curve.
Just pondering.
probably because up to the point of the 195 the minimum cross section was in the head, and after that the minimum cross section was in that tiny POS intake they used for the test. how could they have not known that would skew the results. that test was a joke.
Head min cs 165/1.935 195/2.075 220/2.345 Eldelbrock Air Gap port exit is 1.04 x 1.85 so it was smaller then all the heads, the 195 heads also peaked 100 rpm higher then the other 2.
I think the 218 cam played a big part but it was interesting that the 220 head did not suffer low rpm tq.
It would have been interesting to see a single plane thrown in the mix.
In comparison the first episode had a 400" sbc 220 head with duel plane that made 30 more hp at 500 rpm higher, I think the cam was 236, then it made another 50 hp with a T. Ram.
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