Rallycross 1600 EG on 45's GS6 for my road car...........comments on parts requested.

I have had a load of nice bits on the shelf for XX years (too long to tell you guys, its embarrassing) Anyway, the spec is;
Forged flat top (at the moment..) Mahle race pistons.
12.5:1 CR
GS6 cam
Full race 40:35 longman ported flat head, race valves, schrick springs, fancy top caps
Matched inlet for 45dcoe's
New 45 DCOE's on 36 chokes
Std crank, std rods
Ansa 4:1 long primaries
Std gti dizzy

Couple of questions;
MKS head gaskets have become standard fare for everything new for me, can you get one for an 'old' EG?
The 1588 EG GTI had big bowls in the pistons, what's combustion going to be like with flat tops?
GS6 cam: how long will I put up with it in traffic?

It will be a laugh, I'm sure, and its going into my restored SA Citigolf (4 door, mk1)

Was a very quick rallycross engine in its day (std pistons then), a match for anything in Formula C
Jon

 

Sounds like fun to me Jon

Something really lairy on the road is fun! Some people may comment on how your not going to get the full potential from it but who cares!
I had a 130bhp (12.5 Cr full rave head straight cut gears drops etc)mini on the road that was bit of a pig in traffic with the Ali flywheel and paddle clutch etc
You say it has 12.5 compression already so why ask about the pistons? Confused me?

 

I've re-read that you asking about swirl etc in the cylinder

Sorry for the confusion!

 

Just done some measurements, because its been so so long since I started this.
Flat tops 5.1mm down the bore. With a cheap and nasty 2mm head gasket that's 7.1mm to clear the valve on changeover.
Std cam lift on overlap is 5.86mm so not a lot of clearance, especially as it has Peugeot valves in at 0.7mm proud of the head.
7.1-(5.86+0.7)=0.5 mm ish piston to valve clearance, so not enough. Even with solid lifters
CR calcs out about right though
Think its going to need some 1mm deep piston pockets to get to 1.5mm clearance, easy enough on the mill.
May have to get the block skimmed then though..
Jon

 

bit boring just words, so a few pics always helps....






and one of the mk2 ready rally next week...

 

CR is 12.27 /1 ( based on 79.5 bore and 7.1 mm > 35.22 cc )

 

Thanks, that's the number I got too. Valves protrude down from the head into the chamber increasing it a bit.
The pistons are +.25 to give 1598, just within the class limits.
Need to buy an MLS head gasket today and borrow a 42mm end mill for the inlet pockets.
I have an 1.5" for the exhausts.
Also need to try and find a crank sprocket to suit the small nose of the early crank. Should have one somewhere.
Other than that it should be an easy build.
I have the original 1.26:1 5th ultra CR motorsport box that may get rebuilt, but it'll be a bit extreme in a road car.
Either that or a standard FM/FD GTI box , as I have a spare.
Once the novelty of it on the road wears off, it'll come out and go into my mk1 or and get raced.
It'll mean I can restore the CITI under the bonnet area, as it sorely needs it. And a new steering rack etc.
That's the plan, anyway
Jon

 

1st pass at pockets, only 1mm deep for a dummy build. Decided to go across piston rather than two single round cuts (minimal difference to
CR due to size of valves!) ;

 

Interesting build Jon .

I've seen F3/supervee engines use that technique (slot across the whole piston), plus of course Spiess used to run the pistons down the bore with flat top pistons in the 2.0lrt F3 motors, 1600 EG head though, right up to 1991! They didn't use a cut outs in the pistons, but were very long stroke (95mm?), so the piston got away much quicker from the top of the bore than a short stroke motor.

Those Heron heads flow better than the later chambered head, Jason at JMR reckoned it must be down to the better short side turn in the inlet ports. We put my Spiess one on the flow bench and it was pretty good!

Be a fun motor.

 

Thanks, was hoping for some tech banter, hence the post, sharing my tinkering.
The head is a lovely piece, it should be, its cost me my nice motorbike at the time. (sold the bike to pay for the head!)
No regrets though.

Getting the valve centres correct with round cutouts has been 'fraught' in some of my past builds. 36 and 41 mm end mills are expensive, as is going above an ER40 toolholder. (30mm max tool shank dia)
Found that small nose crank pulley tonight, a good result.
Failed dismally on the MLS head gasket, so its getting an Elring fibre one.
Going to leave the cam lash initially at 30 thou so I can get a plasticine measurement of the clearance on rotation.
The OE GTI combustion chamber swish. Not a lot I can do about this, I have to stick to flat tops to get the compression I need.
Slow process, but will continue to post , if anybody is interested...
Jon

 

Keep the posts coming Jon interesting build coming along

 

Are you going to chamfer the edges of the cut?. No, not really worried, as the step is small. Maybe dress the edge of the piston with a needle file.
I'd be a bit worried about having a 90 degree angle there as it's a stress riser and could potentially crack there. The edge isn't really 90 degrees as the tool has a radius at the cutting edge.
Have you thought about using a fly cutter, assuming you've got a rotary table or could rig something up rather than buying larger end mills? They were done on a rotary table to align the non parallel cuts.
Fly cutters, not a fan, tried them and they shock load the job and the machine.
Anyway I'm a bit of a 'man in a shed' machinist, so I learn as I go.
Hasn't hurt so far though
Jon
If people are reading this i'll keep posting...

 

Another way if you haven't got the right size end mill and one I've used in the past is to take a used valve of the right size and braze 3 pieces of HSS to the face in a Y shape, then mount in a collet chuck and you have a multi edge fly cutter which will reduce chatter and shock loading. Also heard of people putting the valve in the head, on the block and cutting pistons in situ for the correct angle, driving the valve with a cordless drill.
There's nothing wrong with your method just thought you'd like to know of a different way.
Keep posting updates Jon

 

Course we're reading. Beats watching rubbish on the TV! I got so bored I took the m5 for a blast


Anyway, what Box have you to keep it on the boil?

 

Excellent thank, merry xmas.
Tried the bit of tool steel in the old valve before, back in the 'old days' of mini tuning.
Mixed results.
Last thing I would want to do is wear the valve guides, head is near 100% wear free.
Plan is to continue as I'm going, however, i'm always going to listen to advise
Jon

 

Also: box: good question. The 1.26:1 fifth would be ideal, but you change gear every 3 seconds at full chat.
Ratios (MS CR ratio box);
2.72, 2.06, 1.68, 1.43, 1.26 and its currently got a 3.6 FD.
I bought the gearkit to suit the GS6 cam, so its probably right I re use it.
1st will be tall, and fifth low.
Maybe use an FM/FD 020 instead
Teeth size on the MS box is massive though, so strength assured
merry xmas
Jon

 

I struggled with the mls gasket too, not sure how good the fibre type will hold on a hi comp motor, there is a guy in belgium? that can supply mls gaskets for the early head/block single drain any bore size but he's asking 275 euros a pop!

heres a link to it:
ettinger.motionsforum.com/t54-mls-head-gaskets-for-eg-block-to-your-spec

 

sorry the linking is missing the 'o' for oettinger at the start

 

275 euro, too rich for me!
thanks anyway
Jon

 

Above pictures are from my south African mk1 CITI 1595 I stripped and removed today. D shaped crown is not something I have seen
in a conventional VAG group engine.
D just proud of top of block. Head valve dia is 38:33 similar to later GTI's.
Cam is 10.1mm lift, very similar to Dx.
Its a carb.
Put this up for discussion purposes.
New engine major components complete awaiting minor parts before its dumped into the shell.
Couple of pics below;


Jon