1.8L tweek + brake Q

[KURO]

Looking for options for more power in relatively economical way, where I opt to use stock 1.8L head and D-jet. if possible. Some of my questions are:

1) How big p/c can stock 1.8L head adapt (w/ and w/o fly-cut)?
2) What needs to be concerned to go for stroker crank (i.e 71mm stock 914/ bus 2.0L or 78.4mm), using 1.8L head?
3) How far can the D-jet strech to feed more cc's (I read about the trick somewhere and have already recal. P-sensor to mate D-jet with 1.8L when my orig. 1.7 dropped valve)?
4) What's max. compression ratio good for prem. pump gas (91 or so)?

Wish I can just go for RAT's 2270 kit but a bit too expensive for my budget, especially if I need new fuel system (and I'm not a carb. fan!) Hope somebody out here can put me into the right direction.

Thanks for time and advise.


P.S.

My brake genarally works great (BMW320 upgrade front + 19mm MC), but it always tends to become noticably 'firmer' when I first press the pedal then let go and immediately step on it again. Not expecting leak or air bubble as I re-press the pedal it always get firmer (less stroke too) and stops hard. Just annoying because I do not consistently feel the same braking effort/ stopping power. Still got prop. valve. Any idea?

[HMeeder]

Can't answer the power questions, but as far as the brakes go... some people (John?) will tell you to ditch the prop valve in favor of a simple tee. If you have upgraded front brakes and stock rears, the bias should be alright for eliminating that valve. Fortunately, it is a fairly inexpensive and easy conversion, and if it doesn't work right, you can always go back and only be out a few bucks.

Just a thought.



------------------
Herb
'72 1.7 Tangerine 'Teen
'74 2.0 Red Rustmobile

[Jake Raby]

OK,

You can go to 96's without opening the heads and that is about it for the 1.8 style conn.rods....

The ultimate power change is with a 78.4mm stroke, it is a great difference, and it lives, no clearance work needs to be done to the case, only rod clearance and cak base circle changes. I have a 74mm on ebay right now, that will bolt in WITH NO CLEARANCING AT ALL!!

According to heads, induction and camshaft, I go no more than 8.5:1 for the street, with a bore of 96mm...lower on the big bores.

You could save to buy my kit....It saves TONS of time and guesswork...it is a proven combo, and will cool great with a stock cooling system.

[JP Noonan]

Just to clearafy, the 1.7L and 1.8L have a different pin height than the 2.0L so it is critical to match the right P/C's with the right crank/rod.

Jake is right that stroke is going to give you more power than larger bore. People buy horsepower but drive torque. A more "square" rod to bore ratio makes high rpm HP longer rods make more torque.

[Brant]

whether you keep the stock valve or not, you definitely have some air trapped in your brake system. The stock valve is tough to bleed and I'm starting to believe that this is one of the "real" benefits of getting rid of it.

Bleed your brakes again, sometimes I will try to raise the back of the car or manipulate the valve too. If this fails, to to a shop and have them use some pressure. You will love your brakes even more when the air is out and the pedal is consistent.

good luck
brant

[Dave at Pelican Parts]

I know someone who is running a 2.2 liter on D-jet. I'm not sure what the bore and stroke are, but he tells me it is 2.2 liters.

You can try D-jet Mercedes injectors--they flow more than the 2.0 injectors at the same pulse width. That will require some tweaking of the MPS and possibly the rest of the FI as well. Check Kjell Nelin'd D-jet Guide http://www.914fan.net/djet.html for tons of info on the FI.

To reiterate some earlier information: The 1.8 heads will accept 96mm P&Cs without flycutting. Make sure you get 96es that are intended for the 1.8 motor! If you cut them, they'll take up to 105mm ones, though it seems generally accepted that 103 is about as high as you want to go with any hope of reliability.

--DD

[Va914]

Will 96mm P/C for a 1.7, fir a 1.8L?
I might have a good buy on a big bore (96mm)for a 1.7L...I have a completely stock 1.8L with D-Jet.

Thanks

[Bleyseng]

Yes, the 96mm P&C's for a 1.7 and a 1.8 are the same. Only the 2.0l ones are different due to the different wrist pin offset.
Geoff

------------------
76 914 2.0L

[Dave at Pelican Parts]

It may fit, but it will not fit correctly. The sealing area on the 1.8 heads is significantly larger than that of the 1.7 heads. The 96mm kit for the 1.8 uses that, while the 1.7's kit uses the smaller area in the 1.7 heads.

I am not certain, but I suspect that the 1.8 kits are essentially the 2.0 version's cylinders, with the 1.7 version's pistons. That way the cylinders would seal correctly in the larger area of the 1.8 head, and the wrist-pin offset would still be correct for the 1.8.

--DD

[KURO]

Thanks all for continuous discussion.

I guess my plan is most likely to get 96mm p/c (where are those for 1.8L?), and save 78.4mm stroker/ head upgrade for later (hope to find a way to tweek D-jet to feed 2.2L by then.) Can I get 78.4 crank which works with stock 1.8L con rods and the 96mm p/c (for 1.8L)? I got to think this again if I have to get 96mm p/c (or at least pistons, as per Dave) designed for 2.0L in order to make the stroker setup work.

Thanks again.

[JP Noonan]

Ask Pelican or Jake (sorry Jake, but I recommend in that order) about the 96mm 1.8L P/C's the only domestic company I know of who makes them is EBS for $350.

P/C's and a strocker are kinda a one shot deal. You 'could' physically use 96mm 1.8L with a stock crank, then later buy a stroker crank that uses the 1.8L stock wrist pin hieght BUT... Then the piston will be contacting it's worn it part AND the new unused part of the cylinder. If I had to guess it would at least cause oil consumption at worst break rings or crack off the top land of the piston.

About stroker cranks they can't use the stock rods you always need rods with a smaller big end. That is how they are made. Hard to explain in words. You can use the stock 1.8L crank as a core for the stroker crank. The 2.0L crank is basically a stroker 1.8L crank.

[Jake Raby]

We have all our stroker cranks made from 2.0 cores, due to the less machining and better oil passages in the 2.0 center main journal..

We normally use VW T-1 rod journals, they work great, and can give proper rod ratio, easier.

I have used some cranks that had the 17/1800 rod journals on strokers, for some reason oil pressures were weird when it was hot (3 diffferent engines) so I tossed the idea..

Incorrect rod ratios help to starve cylinders of oil and tend to score the 6&12 o clock positions of the cylinder severely...