Hi all,
Hoping to get some advice concerning the reason why my Gaskets and decompression plate would blow through so quickly after a 2 weeks of use, see pictures
I have supercharged a 998 CC engine from a 1985 mini city, the engine was striped and taken to the machine shop who rebored it and fitted the standard flat top +20 thou pistons, the block deck received a 5 thou skim to clean it up.
Fitted a swiftune SW5 cam , centre oil pick up and new oil pump after I ported the oil entry/exit ports to the oil pump to help oil flow. all other component within the engine where checked and new crank bearings fitted.
The supercharger kit was bought about 4 years ago from Jonspeed and comprised the eaton supercharger along with a CAM4810 head which had some porting already done.
Kit came with decompression plate and gaskets and replacement fuel needle.
Ignition is via an coil pack driven from a Nodiz pro mappable ignition drive system fed from a trigger wheel and works reliable so far and was easy to instal and set up.
I know that compression ratio is important and as you can guess perhaps I didn't put enough homework into checking it would be correct for my application.
I have used the Podifold Mini engine compression ration checker available here http://www.podifold....ompression.html
and entered the following spec
Piston size 998/1098 cc +20 thou
Crankshaft 998
Head gasket 2.8cc
Decompression plate 5.8cc
Piston CC =0 cc - flat top pistons
Cylinder head volume 21.4 confirmed by measuring
Piston deck height 22 thou , confirmed by measuring
This calculates a compression ratio of 8.88
Question i would appreciate some advice on is the following
Is this compression ratio figure correct and would it be something that my engine and head set up could reliable work with the supercharger fitted.
Another question, is my base ignition timing (shown below) I have loaded and run suitable with the increased pressure that exists during combustion with the supercharger.
Engine ran very well, temperature was normal, using a HIF44 carb with the supplied jet needle supplied with the kit, used colour tune and didn't show it running lean at all.
RPM / advance
800 / 10
1200 / 12
1600 / 14
2000 / 15
2500 / 18
3000 / 20
3500 / 23
4000 / 25
4500 / 29
5000 / 29
5500 / 31
6000 / 32
6500 / 33
7000 / 34
7500 / 36
8000 / 39
Any advice would be greatly appricated.
Attached Files
Edited by stevemkeen, 26 June 2017 - 07:17 PM.