Dual port Vs Single Port fuel systems

KKV270 · Post by **KKV270** » Sun Aug 23, 2015 12:49 pm

Hi.
Question, what is/are the added benefits (& or demerits) of a dual port engine compared to a single port (all factors held constant...if that applies?)

I'm torn between the two options on a rebuild of a 1600cc I'm doing that originally had single ports but I acquired it from the owner who was switching to dual port. I've never had a feel of any dual port engine.
thank you.

darzoom · Post by **darzoom** » Mon Aug 24, 2015 8:57 am

Single port heads have more torque at lower speeds and dual more torque at higher speeds with the dual port giving about ~3 more HP. We used to race with single port heads (rules of the off-road racing class), stock carb and an Engle 100 cam and had great results for a long running reliable engine. We could run the same motor for an entire season of about 12 - 15 races with the longest 400 miles as the last race of the season.

KKV270 · Post by **KKV270** » Mon Aug 24, 2015 3:05 pm

So, darzoom,

It pretty much depends on ones intention on the engines use... (That's quite impressive for the single port...) What about a bus (a camper) intended for long distance travel with full load (cabinets, family on board) I guess the extra torque on the highway would be a plus....hence dual port!!

My thinking ( a debate within me) if the VW engineers chose the single port for the van, is it that they hadn't yet come up with the dual port or was it maybe designed for short distance??? Not sure if you can, but please try read through my question!!

Thanks for your answer. I'm now better informed.

hercdriver · Post by **hercdriver** » Tue Aug 25, 2015 7:54 am

VW introduced the dual port to for two reasons. Adding a few extra horse power was for marketing against newer designs in the 1970's. It also helped with the newly introduced environmental standards being introduced in the US. I don't think you'll notice a great difference between the two. Both are reliable in their stock form. The greatest increases come from a larger displacement. 1776 cc is a common upgrade with modest gains in performance. The newer style cooling shroud was designed for better cooling. It gives more air flow to cylinder #3 and adds more air to the oil cooler.

For me, it would be a question of parts availability. What can you find more easily? A stock 1600 single port will do the job reliably at the lowest cost.

If you do rebuild, start another thread for us to follow.

Ps This is considered by most a must if you are going to rebuild a VW engine.
http://www.amazon.com/Rebuild-Volkswage ... 0895862255

Blue Baron · Post by **Blue Baron** » Fri Aug 28, 2015 11:10 pm

I prefer single port on a stock engine. You run into fewer carb/hesitation problems.

KKV270 · Post by **KKV270** » Fri Sep 04, 2015 11:24 am

Thanks for the feedback. I appreciate it.
I am yet to decide on which..... I already have with me dual port heads which need new exhaust guides..... (a small challenge as they are from different manufacturers - Brazil and the other I'm not sure. The guides are not the same external diameter plus they are both oversize to stock available spares.)

as for the rebuild material, thanks for the link to the manual. I've been using a service manual that was for the official dealers.....it is quite a resourse.

Please check my next thread.... I need sound advice on the issue. Thanks guys.