Performance 1679cc

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joelsbeetle
Posts: 10
Joined: Tue Sep 19, 2017 2:53 am

Performance 1679cc

Post by joelsbeetle » Fri Sep 03, 2021 10:23 pm

Looking at building my first engine. Any pointers would be much appreciated.

I am not looking for a specific horsepower number. I care more about the ability to be driven hard and with a snappy response.

The car is built for twisty hilly back roads, so sustained mid to high rpms (6000k) is what I am shooting for. Also, needs to run on 91 pump gas.

Parts list (nothing purchased yet):

New magnesium case from scat
CW forged 69mm crank
Scat C35 cam with Scat 1.25 ratio rockers
5.7in H beam rods (questionable, longer rod for moving the power band higher in the rpm range and less wear and tear on pistons and cylinders?)
AA 88mm thick wall cylinders and pistons
Mofoco 042 heads with dual valve springs, heads flycut about 50cc (looking for around 8.5:1 compression ratio)
Dual Weber 40 IDFs
Merged 1 1/2 exhaust


Thank you!

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woodsbuggy1
Posts: 768
Joined: Sun Feb 20, 2011 8:15 pm

Re: Performance 1679cc

Post by woodsbuggy1 » Mon Sep 06, 2021 8:57 am

Hello,
I think you would be much happier with a few changes.
A Web 163 or similar cam could be an improvement.
Stick with stock length rods or you will have other issues.
Look at some Tims heads or similar with port work and stock size valves, way too many issues with Mofoco heads.
I am sure others will help.
Where are you located?
Good Luck
Kenric
Good quality is getting harder and harder to find.

joelsbeetle
Posts: 10
Joined: Tue Sep 19, 2017 2:53 am

Re: Performance 1679cc

Post by joelsbeetle » Mon Sep 06, 2021 9:21 pm

Thank you for the response Kenric! I am located in Placerville, between South Lake Tahoe and Sacramento. I'll look into the web 163 cam. I was considering Tim's heads as well. What are the headaches associated with the mofoco heads? I could only find one review of someone who was upset. I am looking for something that will flow nicely but won't sacrifice cooling capabilities. It's been 90+ degrees here almost everyday this summer.

Thanks again,
Joel

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woodsbuggy1
Posts: 768
Joined: Sun Feb 20, 2011 8:15 pm

Re: Performance 1679cc

Post by woodsbuggy1 » Tue Sep 07, 2021 7:04 pm

Joel, why not use 92mm thickwall instead of 88?
I do not want to bash anyone, just have not been impressed with Mofoco products and service. Apparently there are happy customers out there too.
Talk with whoever is doing your heads, they will have more knowledge and experience than me. Be honest with them about your goals and they should be able to recommend an engine package to fit your needs. I have had great experiences with Brothers VW, you are very fortunate to be in the state with the most VW shops.
Please keep us posted with your engine build.
Kenric
Good quality is getting harder and harder to find.

joelsbeetle
Posts: 10
Joined: Tue Sep 19, 2017 2:53 am

Re: Performance 1679cc

Post by joelsbeetle » Tue Sep 07, 2021 9:41 pm

I was thinking about building an 1835 or even a 2021 (76mm stroke) but kind of liked the idea of building a decent performing "1600". I understand the price is essentially the same.

I stripped out the interior of the car for the most part and removed the big ol' bumpers and am planning to get carbon fenders, deck lid, and hood to reduce as much weight as possible.

I wanted to see how far an efficient cheater 1600 with weight reductions could get me. Also, I'm hoping this won't be the last engine I build haha.

Is the 5.7 inch connecting rod an issue due to the "a" style piston skirt of the AA 88mm? I am planning on reaching out to scat vw to get their opinion on rod length, stroke, and piston skirt. They probably get these kinds of questions all day so we'll see haha. But is there a benefit to running short "b" piston skirts on a non-stroker crank?

Thank you!

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joelsbeetle
Posts: 10
Joined: Tue Sep 19, 2017 2:53 am

Re: Performance 1679cc

Post by joelsbeetle » Wed Sep 08, 2021 8:41 pm

Here is an updated parts list: https://docs.google.com/spreadsheets/d/ ... sp=sharing
I am still missing a lot of things and I haven't reached out to SCAT or the guys over at performanceworkshop.net.

If the rotating assembly is properly balanced what is a realistic redline limit without the engine melting or rattling apart? From what I have read the hypereutectic pistons are good to around 6500 RPM. Are the pistons going to be the limiting factor? Maybe I need a slightly more aggressive cam—I was reading the Web 163 fizzles out around 5800 RPM with 1.25 ratio rockers. Maybe Web's 109 cam with 1.25 ratio rockers... thinking continues...

Ol'fogasaurus
Posts: 16910
Joined: Tue Nov 14, 2006 1:17 am

Re: Performance 1679cc

Post by Ol'fogasaurus » Wed Sep 08, 2021 9:24 pm

Your idea of thinking ahead for options ​is a good idea.

Best advice is to allow for future updates to the block such as from possible damage to the block from cylinder damage (lost one block to a cylinder problem) allowing for larger cylinders update to the block. There are also some blocks (certain years) that are better to work with than others.

Cam design has a lot of options to look into also. What will you be using the engine for for example.

Almost everything has options which can drive you crazy too.

Lee

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Schweg
Posts: 1106
Joined: Sun Feb 04, 2018 4:48 pm

Re: Performance 1679cc

Post by Schweg » Thu Sep 09, 2021 8:04 pm

Are you just looking to hit 6000rpm to hit that number?

It will be easier to know what recommendations to help with.

Are you thinking carbs? EFI? Turbo?

All those things will change some of the build items.

joelsbeetle
Posts: 10
Joined: Tue Sep 19, 2017 2:53 am

Re: Performance 1679cc

Post by joelsbeetle » Thu Sep 09, 2021 11:11 pm

I will be running dual Weber 40 IDF carburetors, no turbo.

The reason behind the higher rpm range is I am planning on getting a close ratio transmission and I enjoy winding out engines, plus aircooled engines sound cool when revved. I am not looking for a super peaky top end but a power band ranging between 3000-6000ish, seems like it would help with the 4 speed on back roads that range from switchbacks to high speed sweepers and straights.

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joelsbeetle
Posts: 10
Joined: Tue Sep 19, 2017 2:53 am

Re: Performance 1679cc

Post by joelsbeetle » Wed Sep 15, 2021 11:21 pm

I reached out to DPR. I feel like it makes more sense to purchase a cw crank, rods, flywheel and crank parts from the same company that also offers balancing the rotating assembly. I've read good things about DPR and reworked VW parts and I like the idea of supporting a "local" shop. It would be awesome to hear some more feedback from people who have worked with DPR and if the quality beats the Chinese rods and cranks offered by scat and cb.

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