Welcome, Guest. Please login or register.
February 27, 2021, 07:28:23 PM

Engine build options

This is a discussion for the topic Engine build options on the board Beach Buggy Engine and Exhaust Help.

Author Topic: Engine build options  (Read 861 times)

this user is offline Guy

  • Full Member
  • **
  • Posts: 93
on: April 26, 2020, 09:25:02 AM
Hey everyone. I thought I would open a can of worms here with a engine question.

Here is my position. 1600 dual port with excessive end float, crude measurement of 1.5mm so the case should be good for a oversized thrust bearing and possibly a line bore.

Cylinder heads a genuine VW, they need new valve guides but look good for reuse.

I have a set of Weber IDF 40 (Spanish) and a AS code gearbox.

I guess the big question is. Do I sort out the bottom end and keep the 1600 (pistons and barrels are evidently quite new) and add a cam, up the compression and flow the cylinder head or go bigger?

What I want to avoid is throwing out the crank, rods, lifters etc etc and having a massive parts bill. I don’t mind however machining the cases to accept a larger cylinder.

Thoughts?


this user is offline farmer rob

  • Buggy Meister
  • ****
  • Posts: 1638
  • northants
  • SWB Rat
Reply #1 on: April 26, 2020, 10:24:33 AM
If your cases have not been line-bored before, they might recondition with another line-bore but you can not tell until it it stripped down. Reconditioning these engines usually costs £700 upwards and of cause if you put upgraded parts in them, then the bill gets bigger fast. If you upgrade one part, then you have to upgrade other bits. When you upgrade the cam, you have to get new lifters, HD springs, collets and retainers, push rods and bolt up rockers. And if you want it to last, it will need a full balance. That will add another £400 to the bill. If you go bigger, you will want all the above goodies plus head and case machining for larger B+P's, £180-200 plus £275 upwards for B+P's. So a mild 1776 for example comes in at about £1600 plus when done properly. You will just have to work out how much you want to spend, but power isn't cheap  ;D ;D

Rob


this user is offline Guy

  • Full Member
  • **
  • Posts: 93
Reply #2 on: April 26, 2020, 10:35:59 AM
Aircooled 4 bangers are a bit of a unknown to me. I know how to build 2 stroke performance engines and have some experience in 4 stroke water cooled. They were modern OHC though.

I would think a 1600 would be enough in a buggy but I see a lot of people saying otherwise.


this user is offline farmer rob

  • Buggy Meister
  • ****
  • Posts: 1638
  • northants
  • SWB Rat
Reply #3 on: April 26, 2020, 01:47:30 PM
The 1600 engine is only 50HP, a lazy slogging engine that only rev's to about 4,000 rev's. So people do get a bit bored with them after a while. As you have got some twin carb's already and decent 1600 B+P's, you could just soup it up a bit with an Engle 100 or 110 camshaft with the other mods I said. It would then give you around 70HP at close to 5,000 rev's if you have a tuned 4 into 1 exhaust system on it. If you have a buggy cannon type exhausts ( The one exhaust on each side type) this will strangle your engine so it will not rev past 4,000 to give you any more power from any engine mod's. A lot of people are happy with a mild tuned engine like this!. Another point for you to think about is your gearbox. The AS code box is a high ratio box that came off the GT beetles. They are getting a bit rare and are worth up to say £500 !!! However with a 1600 engine and the larger buggy back tyres, you might find that the ratio is too high. So I would say, see if it works with the engine spec you choose and if not you can easily sell it and get a lower ratio box.

Rob 


this user is offline Guy

  • Full Member
  • **
  • Posts: 93
Reply #4 on: April 27, 2020, 12:36:14 PM
Thanks Rob.

I think I will bite the bullet and up the displacement.  I understand my twin 40 IDF’s are good up to 1915cc.  Which has the thicker cylinder wall? 1776 and 1915?

I was thinking 1915 piston and cylinders, 110 cam, lifters, chromoly push rods, HD valve springs and flow the twin port heads I have 32/35.5, run compression at 8.5/1. Full flow oil and a good ignition system. Using the stock crank and rods (if they are ok on inspection) get them dynamically balanced.


this user is offline farmer rob

  • Buggy Meister
  • ****
  • Posts: 1638
  • northants
  • SWB Rat
Reply #5 on: April 27, 2020, 01:45:48 PM
If the crankshaft is dynamically balanced, they are good for 5,000 rev's. You get flex if you go higher than that but with standard size valves a 1915 engine will run out of steam by then. You can get counter-balanced cranks with a choice of strokes but these start from about £300 upwards, which are stronger. With a 1915 engine your AS code gearbox will be great!. If you stop with your crankshaft, you will need to get it 8-dowled and get a chromoly gland nut to hold the flywheel on. A lightened flywheel ( 13lbs or so ) works well, the after market ones are already 8-dowled. with all the extra power you will also need a Kenndy Stage 1 pressure plate to stop your clutch slipping; a standard 200mm friction clutch plate is fine.

The standard con-rods will be fine but some put upgraded bolts in!! I will leave that to you lol. There is not much difference in the wall thickness between the 1776 and the 1915, the 1835's have thinner walls. When machining cases for 1915, there is a bit of extra work to do because the cylinder seat has to be re-cut as well as the hole diameter, otherwise there is not a nice flat surface for the cylinders to sit on.

Rob


this user is offline Roadrunner

  • Buggy Meister
  • ***
  • Posts: 1525
  • Henlow, Bedfordshire, UK
  • FF LWB
Reply #6 on: April 27, 2020, 01:57:03 PM
If you want the thickest cylinders then look at the 1835 thickwall, the case is machined for the 94mm cylinders.

There are 2 types of the 92mm cylinders, the ones where the case is machined for the 90.5mm cylinders or the 94mm.

So thickness are as followed

Cylinder diameter (mm) Engine displacement at 69mm Crank (cc) Cylinder Thickness (mm)
85.51585 (stock 1600)4.15
8716413.4
8816792.9
90.517763.75
92 (thin wall)18353.0
92 (thick wall)18354.55
9419153.55

Also as Rob says lightened flywheel.


this user is online Merscury

  • Buggy Lord
  • *******
  • Posts: 746
  • Nottingham/Derby
  • Predator
Reply #7 on: April 27, 2020, 05:05:17 PM
There is another thick wall 1835 where the cylinder head is machined for 94mm but the case is only machined for 90.5mm, it's only the spigot at the case end of the barrel that has the thinner 3mm wall,  I think it's only made by AA, their part number is  VW9200T1K
Have fun. Be lucky