| Single or Dual |
| Single Port |
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56% |
[ 54 ] |
| Dual Port |
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43% |
[ 42 ] |
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| Total Votes : 96 |
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| Author |
Message |
Lingwendil
Samba Member
Joined: February 25, 2009
Posts: 3988
Location: Antioch, California, a block from the hood
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 Posted: Fri Aug 26, 2016 7:48 am Post subject: Re: Single Port vs. Dual Port |
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| 67jason wrote: |
| Lingwendil wrote: |
| Bob Brugge wrote: |
| Anyone that claims they can go over 77 MPH with a STOCK SP engine is lying. Straight up! Just take their advice right out of the mix. I can barely reach 83MPH in my 70 std bug with all stock 1600 except for the 87mm jugs. |
What are you on about? Stock 1600SP with a stock cam, 205K distributor, 30PICT-3 carburetor, Oil bath air cleaner, and basic 4-1 header (modified for proper heat riser operation) can reach 85MPH when properly jetted, maintained, and tuned without issue. All stock parts in the bottom end, driving in a 69 beetle with stock tranny. Verified by GPS. Not getting into any discussion as to what people think shouldn't happen, all i can tell you is my personal experience, take it however you will...
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replace 205k with 010 and 30pict3 for 30pict1 and you'll have me pulling 95+ in my 67 with stock geared trans and 165/80's on all 4 corners.
ya I beat the snot out of it, but it did go faster then 77mph  |
See, experience speaks for itself!
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Alstrup
Samba Member
Joined: July 12, 2007
Posts: 7221
Location: Videbaek Denmark
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| Posted: Fri Aug 26, 2016 1:09 pm Post subject: Re: Single Port vs. Dual Port |
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Well, I think the 77 mph claim was with a stock engine. As stated earlier the 1500 sgl port has a factory top speed of 130 km/h (about 80,7 mph to be exact.) and a properly adjusted stock 1500 will do that. the 1300 sgl port is rated 75 mph.
Top speed is a relative thing. Some people claim very high numbers and back them up with "sun in the back, slight tailwind, slight down hill" etc etc.
A stock engine with only minor improvements like f.i. a 4 tuned header, that is tuned to be on the edge will soon ad 5 mph to the factory top speed.
I sort of agree on Lingwendilīs sp set up. I have built a few of those. Hereīs one with the 2280 cam that has 8,5 CR, runs a 34 Solex on a CB/Empi manifold and std Ernst muffler : https://www.thesamba.com/vw/gallery/pix/1117015.jpg
I later built another one almost like it, same duration but split lift on the cam (445/394" for those who are interested) with my/TTīs std plus muffler instead. canīt locate the dyno file, I may have erased it by accident. Anyway it pulls 70 hp at approx 4500 and 132ish Nm torque. In a ghia, with a 3,88 R/P and 0,89 4rth that one pulls a solid 93 mph. and then it is all over, no more rpm power.
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atticus finch
Samba Member
Joined: March 06, 2014
Posts: 126
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| Posted: Sat Aug 27, 2016 9:28 am Post subject: Re: Single Port vs. Dual Port |
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| andk5591 wrote: |
Agree - with that displacement and that size carb, you will be starved at higher RPMs, but maybe you dont care....This is something that you can measure though...We did that on a dyno with dual 40mm on a 1955 to make sure I wasnt restricted and I wasnt.
There is more to this subject than I know. But I do know that smaller intake helps at lower RPMs and larger is better at higher. This is one of the reason dual planes are popular on street V8s and such. But do more research - this stuff isnt rocket science and has been sorted out decades ago. |
Agreed it'd be restrictive at higher revs, however what defines higher revs?
I'm guessing past 4000 rpm or so depending on the factors involved?
You're correct I don't care about that as that doesnt negatively affect what I intend to accomplish. Per your post you partly put your finger on the why of it.
I won't be running revs above 4000 hardly ever, I don't now and won't need to. Consequently IF a single port is better than a dual port say 4000 rpm and below, then that'd be a better choice for my purposes. However IF a dual port will match or remain very close to the torque curve of a single port at 4000 revs and below and offer the prospect of a bolt-on HP increase with no loss in reliability or driveability (torque curve) then there's no reason to not take advantage of something like that. |
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Brian
Samba Moderator
Joined: May 28, 2012
Posts: 8340
Location: Oceanside
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| Posted: Sat Aug 27, 2016 8:28 pm Post subject: Re: Single Port vs. Dual Port |
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I'm almost 2,000 miles on my 2007cc single port and single 34 pict3. Jetting is way off so I flood on hills but I'm happy with it. I can spin it over 4 grand but there isn't really any point, power drops off a little before it.
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