6 replies to this topic

[detroitmini]

Hey all,

 

Thought I would log my engine build hear to show my thinking and maybe help someone in the future/get my own help.

 

My engine was leaking oil and coolant, so I decided to tear it down, replace the seals, and repaint for a fresher looking engine bay (pics of starting point to come). The engine is starting as what I believe to be a stock 998 with a HS4 single carb and pancake filter. As with most projects, I hit the slippery slope and started debating engine upgrading. I currently have a 12G202 head laying around (got in the purchase of the car) and what I believe to be a pressed steel exhaust for a mini (see attached. may be for a b series). My buddy happens to have a 266 cam laying around. 

 

So the final plan would be to have:

FDR: See below in questions

Stock block and crank

266 Cam

Stock pistons

12G202 head skimmed for 10:1 CR and ported

Stock Rockers

HS4 with stock intake (cut from exhaust)

Pressed Steel Exhaust

 

Questions:

- Will the upgrades give me enough power to drop to a FDR of 3.1:1? Would love to get some higher top end speed as here in Michigan there is a lot of highway driving.

- Is the HS4 big enough? i also have twin HS2s I could switch to but I like the simplicity of single carb.

- Will I need the Aldon Yellow Dizzy? i have seen most people upgrading convert to these.

 

End note:

I do have the Vizard book and reading as I go along.

 

 

Attached Files

•  Mini Exhaust.JPG   21.82K   0 downloads

[unburntfuelinthemorning]

The engine will pull a 3.1:1 final drive but you'll lose a lot of the sparkle.  In my opinion 3.44:1 is the highest ratio worth using in a 998 but then if you're mostly cruising on the highway it may not matter, as long as the hills aren't too steep!

 

Carb is big enough.  You could increase the airflow through it a little with the Vizard mods.

 

Not sure about dizzy.

 

12G 202 head is standard fit.

[detroitmini]

Awesome. yeah sounding like I am going to stick with the 3.44:1.

[Gilles1000]

For me the 12G202 is a cooper 997 or 1100 head, not standard for a 998.

But it is a bit better as the original one mostly due to slightly bigger valves.

[detroitmini]

For me the 12G202 is a cooper 997 or 1100 head, not standard for a 998.

But it is a bit better as the original one mostly due to slightly bigger valves.

 

Gilles, that is correct. However, with some porting and decking I have heard great things about it on a 998.

[unburntfuelinthemorning]

I thought I'd seen that the 202 heads were also used on 998s but maybe I didn't.  Still it can still be worked on well, I have this one from Keith Calver and it certainly increases the torque/power output on a 998 nicely.

[detroitmini]

Using Vizard, I started to port the heads. Roughed out one cylinder. Now time to rough the others and compare/adjust volumes between them all.

Attached Files

•  Porting.jpg   36.03K   1 downloads

Edited by detroitmini, 12 February 2020 - 04:10 PM.