Discussion in '8-valve' started by gti1600project, Nov 10, 2010.
I agree, I'll be having the gearbox rebuilt and LSD fitted.
You need to pay a visit to Dan's shed... it's an Aladdin's cave of VW engines and gearboxes
RyanMac on here was selling a 1600 GTI engine, if you need a starter unit. Not sure if he's still got it.
Are you subject to any 'period parts only' restrictions? If not, you might want to look at the later X-flow heads, as already mentioned.
What sort of Alfa did you race? Any juicy rolling shells and collections of parts lying around??
I used to run a full house 1600 in auto and rallycross. Good engine. The std big dish pistons will work, obviously heavily pocketed. If you run a real wacky cam (i used to use a GS6) you will need a proper very close gearset to keep it buzzing. My power band was 5-8000rpm. It would die at less than 5000 during rallycross starts. 40's ? No chance. 45's or 48's
It was an Alfa sprint, great car, all sold now i'm afraid. I wouldn't be restricted to period parts but a crossflow head wouldn't be ok unfortunately.
Thats a pain! Any one after a pair of 40's!!
It's my Spiess head on Ebay at the moment. Truth is I'm not that bothered about selling it as it's a work of art in it's own right hence it's not priced to keen . My only reason to sell it was as I want S/C dog box for next year so funds are needed. My current 8v engine is now far better than the transmission and front end so serious work is needed over the winter.
If I can't get what I want for the head my plan was to build a mad 1600 8v engine for tarmac rallying as I believe they run a 1600 8v category and I reckon we could be very competative in that class with a MK1 GTi. As I recall Judd were claiming 200+bhp for their Supervee motors so there is no reason that this setup couldn't produce some decent power and it would sound the dogs wotsits. My current long stroke 2.0ltr motor runs to 8k plus while still making useful power so thinking about what a 1600 would run to makes me smile
Actually, that post ^^ reminds me that a mate who's building a touring car replica was planning on starting with a Supervee engine too. Might be the best way to go, if you can find one.
Class for 1600 8V tarmac cars. Tell me more please.......................
What I meant to go on and say (got kicked off the computer here) was, as Mike H mentioned, that a Supervee or F3 engine could be a good start but they are like rocking horse **** now and even if you can find one the historic racers want them, but you might get lucky. F3 engines are probably less useful in Std form as they are not built to rev but the dry sump and top ends are second to none. Supervee engines were built to rev more. If you even could buy kit of the same spec and quality now you wouldn't be able to afford it!
Whilst you can't go down you local "fast road/race shop' (you wouldn't find anything of any use in there) there is still lots out there if you look. Unlike some makes the bottom ends are solid even for mild race use. Decent big end and con rod bolts is all that's really needed (+L&B). So if you can find and ex race top end and induction, get a set of bespoke pistons made and fit a proper baffled sump you will have a cracking engine. Even if you can't find a decent second hand top end there are a few guys out there (and on this forum) who could sort you out a decent head. All of the valves, cams, springs etc are still available. Schrick and G&S still list the Spiess F3 41/36 valves for example.
As I said I think an 8v 1600 would make a cracking engine and wouldn't need to cost a fortune with a little ingenuity.
Sounds like good advice, thanks. Do pistons need to be bespoke or would something similar to these that 'chopperoli' suggested do the job?
for historic racing, i think you need block and head from the EG
we raced a golf and scirocco from `78>`83 , with Nothelle and Misczyk 1600 EG engines
to gr1 / gr1B / grA regulations
bottom end fully balanced, bafled sump, lw flywheel, pistons CR about 11/1,
head ported , reworked STD valves
K jetronic with Bosch / VWM ``stufenschlitz mengenteiler MT 80 `` and Audi 5 cil TB
ported OEM exhaust manifold with fabricated downpipe and flammenrohr
(megaphone side exit /Very loud )
ign timing @5000 rpm 44-48 degrees /with silencers up to 54 degr ( w.o vacuum tube on) cams were used 302>312 with 11.4 mm lift but found the 306 /105 degree the most driveable 5500 > 8000 rpm
this made 150 > 155 PS
dont use the std EG solid lifters for racing
with good lubrication these engines are bulletproof
Didn't read that one!! Haven't looked at the link but they don't need to be bespoke, it's just that most pistons that will do the job will be I would think. Depends on what cam you run. As he said minimum of a 304 cam I would think.
I ran a 304 with 45's on my last engine (2E/DX) and it ran like a pussy cat but was on mapped ignition. I currenly run a 320 cam with mapped ignition and injection and whilst it it still runs like a pussy cat but spits neat petrol out at a 1200rpm tickover!! Not a problm on a race car but if it needs an MOT a bit tricky but not impossible . That said there are many combinations of lift and duration, Mr hillclimber has a few tricky cam profiles that he uses that he sources from Kent I think. He may be able to help with some pointers on cams, I just like as much lift and duration as I can get!! The madder the better.
The more duration you have the more static compression you will need to regain the dynamic compression due to the valve overlap. I run over 13:1 compression on my current engine but it's reasonably simple to workout on a chambered head. With a Heron head you need to factor in the valve cutouts as this will affect the actual compression ratio. I did plan on building a 2.0 ltr long stroke engine using the Spiess head on a 2E bottom end but struggled to get a piston/rod combination that would give enough Bowl depth and get down to 13:1 compression. Not a problem on an F3 engine where they run 15>16:1 compression but no good for what I do! Any way would be simpler on a 1600 engine as there is enough compression height to play about with bowl depth which is why I didn't use the Spiess head in the end but would if I was building a 1600.
Thats fair enough. 40's have a realistic choke limit of 34mm, after that the restriction becomes the aux vent, and too big a choke reduces air speed and can result in a good fueling spred being difficult to achive. A 34mm choke is on the upper limit of 160hp, achievable, but little scope to improve.
On the plus side, the spec would then be a little tamer and that would be reflected in the cost.
What sort of power are the opposition running?
As for the head, there's nothing wrong with the original type head, it'll more than do the job in terms of perfomance when modded correctly. Keeping the heat transfer away from the inlet is a must tho.
If necessary i'll sell the 40's and get a pair of 45's. The opposition varies, I had a class win previously and a few 2nd's with my Alfa which had 134bhp, but handled fantastically. I had approx. 160bhp in mind, I'd be happy with that, a good gearbox and suspension set up.
Reference heat transfer, I had figured as much. I thought I would heat wrap the exhaust, put a shield between the manifolds and pipe cold air to the carbs. Would that take care of it?
More or less yes. I've seen a 6hp gain by placing a heat shield between the manifolds in a temp controlled dyno cell, there can be a 10hp loss in the car with high air temps around the bulkhead, so it's very important... as is setting up... a lot are rolling road tuned as the temp comes up, then go out on the road, lean down and either lose performance or melt down... air temp (as tested before) comes back to normal out on the road.
There would be no problem to try it on the 40's to start with and swap to 45's if needed, that could be established on the dyno... 160hp is on the cross over... but if you were only talking a few hp and you've had top results with 134hp before, then 150-160hp is going to get the job done.
If you want to push for as much power as "possible" then the spec will need to rise to suit.
There's lots of options.
As far as I am aware, down here in Wales anyway, they run a 1600 8v class as well as 1600 16v and the same for 2000 8v and 16v in the tarmac rally champs. It seemed like a good idea to me as it would provide a good range of budget options as you would imagine the guys who have greater hunger for results and are willing to spend more money would go 16v. That would leave people like me happy to play in the 8v class.
Must admit I haven't looked in to it in great detail but I'm sure that's correct. When I race at Llys Y Fran hill climb there is a MK1 1600 rally car that turns up. The father and son team who run it seemed to be collecting a few trophies when I was up at the Welsh Motor Clubs awards dinner early this year so I guess the 1600 MK1 must be competitive in the right hands.
Tony, you mention the need for valve pockets when using a Heron head. I vaguely understand they are needed if using a long duration / overlap camshaft. What I don't understand is when they become necessary. The standard 1.6 EG has no cut outs.
Do people tend to design these valve pockets on-the-fly with a piece of clay in a dry build engine? Or is there another science or key point behind it that I am missing?
A related point is that as you advance the cam you lose piston to inlet valve clearance and conversely as you retard the cam you lose piston to exhaust valve clearance. So if using a vernier pulley, presumably you make measurements at nominal, and maximum advance/retard to check clearances?
I am also led to believe that these large cut outs in the piston rim aren't great for combustion (kills squish band) and obviously the compression volume lost needs to be made up in other areas.
Presumably its not worth messing with the piston squish band much? (head clearance / piston lip width).
Technically speaking, that is...
Big lift at TDC with race cams... with the flat head, the valve head is closer to the piston.
The clay method is the most reliable, as the pockets are then in the right place to suit that particular engine.
Subject to the engine and cam spec, you just need to make sure you allow for the lift at tdc, and add a little for safety/stretch at rpm etc, the type of rod used will come into play there... steel rods stretching less than std rods.
The trick with A-series Mini engines years ago was to machine a slot right accross, in effect joining up the cut-outs. But many still use simple cut outs... I have them in mine, and dont have a power issue... but "maybe" it may make more slotted accross.
The squish should be tight... 40 thou is safe, 35thou good if your confident of the spec.. a little more if your very brave and "everything" is bang on. Although some claim power gains when opening up the squish band on some engines... not necessarily VW.
How can you get a precise measurement off a clay/plasticene indentation?
Always baffled me. If it lifts or moves when the head comes off, head back on, time it up, try again? It could go on for days! Plus you don't know what cam timing you're going to run it on, on the dyno
Tiz easy... smear of grease on top of the clay/plasticine.
You just allow for a rough lift change, and only swing that amount... they dont normally need/respond to much changing if you get the static setting right.
Thanks for your reply. It's a shame most cam makers don't give you the lift at TDC. I would be able to design on paper before dry builds that way.
I can't see any advantage for slotting across both pockets on Mini pistons, other than ease of machining.
I work out the squish band on a standard chambered 1.8 head, 86.4 crank, 144 rod & std piston to be 0.6mm. All good. But on the Heron head, 80 crank, 136 rod & std (bowl) piston, it's 3.3mm?! That has got to be for to valve clearance, but it sounds far from ideal... A compromise maybe? Reduced squish band, but lighter piston with better shape?
Do any of the high compression pistons for the flat head engines have a higher top (with cutouts) or is the C/R just increased but reducing the bowl size I wonder.
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