Recipe for Frankenmotor

[green71]

I'm still seeking resolution to the thrashed distributor drive gear (brass gear on crankshaft) on my 1.7. The availability of an inexpensive, carbureted 1.8 is making me consider a couple of alternatives:

1. 1.8l case, crank, P/C's, & heads w/1.7's D-jet FI and dizzy

2. 1.8l P/C's/heads w/1.7l case, crank, D-jet & dizzy (new brass gear pressed onto crank, or use 1.8 crank)

Will the larger displacement yeild more HP? Or will the higher compression 1.7's be more powerful? If so, it's option three:

3. Skip the 1.8 entirely; bite the bullet & rebuild my 1.7.

Any input would be great!

TIA,

Mark

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1971 1.7l 914

[DDS]

I have a brand new FAT 440HP cam, lifters and gear for Herr motor. email me if interested.

[JP Noonan]

1.8L block has windage tray 1.7L don't. Remove the head gackets to gain compresion ratio, the 1.8L has larger valves than the 1.7L.

You'll have to tweek the D-Jet to work, use an O2 sensor and play with the fuel pressure and resistance to the CHT, last resort is to buy a used MPS from a Volvo or something close to 1.8L and mess with it. I wouldn't play around with your 1.7L MPS if it is still good.

[DDS]

FWIW, if you are going to rebuild anything, ditch the 1.7. Sell the d-jet parts. If the 1.8 heads are good and you've got dual webers or dells I'd bite the bullet and build a hopped up carbed 1.8 or bigger.
You're gonna buy a cam and lifters and split the case anyhow...

[Dave at Pelican Parts]

A stock 1.7 motor made more HP than a stock 1.8 motor because of higher compression (8.2:1 versus 7.3:1).

Some early 1.7s did not have the windage tray, later ones did.

The 1.7/1.8 bottom ends are effectively identical apart from that. The P&Cs and heads are where the differences were.

A high-compression 1.8 with a carb-oriented cam would make quite a bit more power than a stock 1.7 engine.

--DD

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Pelican Parts 914 Tech Support

A few pics of my car: http://www.pelicanparts.com/gallery/Dave_Darling

[green71]

OK, I've read it several times & am slowly, finally learning it: HP=$$. It'd be just like me to continue to pour money into performance like a crack addict . . .

I'm definitely keeping the FI, which works great. Besides, I just don't have the dough to replace a bunch of parts unless necessary. If I get into the 1.7 & find that the pistons or crank are shot, I'll obviously have to reconsider this.

I thought I might get away with a little extra muscle on the cheap. Somebody slap me!

Thanks for the responses,

Mark

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1971 1.7l 914

[DDS]

Even a rebuild costs $$.
SLAP!
Just a WAG but my 'budget' performance-oriented rebuild will probably cost $1500-$2000, I'm not cutting any corners, but I scrounged and horse-traded for parts big-time.
You can easily spend more on the heads or pistons and cylinders than the bottom end. Between the two motors, you've probably got a useable crank and rods. (I have 2 sets 2.0 crank and rods, both are fine) All you'll need is polished journals, rebushed and resized rods, bearings and goop. (IIRC about $200 or so?) The bulk of the cost will be in the top end. (pray, then look for head cracks)
Per DD's advice to me, you'll want to replace the cam and lifters anyway (he was right - mine were shot, I'll bet yours will be at least worn)
Good Luck.

dave



[This message has been edited by DDS (edited 11-06-2001).]

[Va914]

What is the best way to bump up the compression ratio on 1.8L? Flycut the heads?

I was thinking 8.5:1 would be good on pump gas.

Thanks

[Dave at Pelican Parts]

Yes, fly-cut the heads. Just make sure you've got 0.040" worth of clearance between the piston and the head at TDC... You really don't want the pistons to hit the valves or heads. You may need to trial-fit everything and use some modelling clay to measure the clearance.

--DD

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Pelican Parts 914 Tech Support

A few pics of my car: http://www.pelicanparts.com/gallery/Dave_Darling

[SteveStromberg]

Replace The stock 93's with 94 Type1 pistons you will get about 9to1 comp berfore you add spacers under the cylinders. Steve