1.7L to 2.0L EFI

cassidy-online · 09-24-2003, 11:13 PM

Hi,

Dose anyone know if you can put a 1.7L EFI on a 1.7L engine that has been built to 2.0L and have it work correctly? I read something about how to do this once but can't find it now.

Thanks, Chris.

hardflex · 09-25-2003, 04:56 AM

I've read it can be done. I 'll know soon enough. I'm trying it first with the 1.7 injectors, and if that doesn't work, I have some 2.0 injectors to put in as well.

I do plan on adjusting the MPS, but since it's a 1.7 unit, nobody cares.

Are you using a stock cam and 1.7 heads?

cassidy-online · 09-25-2003, 06:28 AM

The engine is a 1.7 Built to 2000cc 94mm pistons & cylnders. 2.0 Crankshaft 2.0 Connecting rods I think the cam is stock.

Chris

pbanders · pbanders's Garage

The simplest way to do it (and it should be pretty close to right) is to use 2.0L injectors with your 1.7L components. Most of the variation in D-Jet applications due to displacement was accomodated by different injector flow rates. Your 1.7L intake does not flow as well as the 2.0L, so there will be some differences in volumentric efficiency (handled by the ECU), but they're likely to be second-order effects.

Bleyseng · Bleyseng's Garage

Hopefully you have the 73 ECU, so you can just use the 73 2.0 MPS (037) and the 73 CHT with the 2.0L injectors. This should work fairly well. Don't just use the 2.0L injectors with the 1.7 MPS as I have seen this and the cars run lean.(twice at dyno days)
Geoff

KURO · 09-25-2003, 08:16 PM

Chris,

I'm in the same boat. Will build up a 2.0L this coming winter.

Currently I have 1.7L D-jet (original from my '72) on 1.8L (my second motor) w/ no problems. With 2.0L, hoping I can get around using 1.7 injectors by cranking up fuel pressure (I think I read somewhere that max you can go is 31psi???) as well as tweaking MPS, etc. hardflex, let me know what you find out!!!

I have 1.8 heads mating w/ 1.7 T.B., instake runners and SS exchangers, in other words, poor man's 2.0. With Euro OEM P/C, I expect little higher compression ratio (due to smaller chamber volume w/ 1.8 heads, I will cc to make sure it is not too much), and hoping to WASH some shortcomes from not using 2.0 components. Anybody any idea of expected Hp/ torque? Cam will be stock too.

Also has 1.7 distributor. Not sure if one for 2.0 has different advance curve, and more importantly, helps measurable performance gain?

By the way, why 1.8L heads have no vent tubes to hook up breather hoses (like 1.7L heads)? Should I vent?

Thanks,

Kurt

Bleyseng · Bleyseng's Garage

Switch to a vanagon 2.0 Throttlebody as it fits the 1.7 sidedraft setup.
I don't know if the 1.7 injectors will flow enough, all the setups I have seen switched to the 2.0l injectors. You don't want to go lean!
If you did use the 1.7 injectors you could adjust the MPS while at a dyno shop to set it up correctly. It would take some time although.$$

Geoff

hardflex · 09-26-2003, 11:24 AM

I 'm wondering about the 1.7 injectors myself. DNHunt has the megasquirt system and said the 2.0 injectors were too big for off idle transition, that's why i'm going to try the 1.7's first.

I'd really like the 1.8 runners with the 1.8 heads to give more capacity. Then I think it could be real close to thee 2.0 system.

pbanders · pbanders's Garage

Just remember, guys, if Bosch thought they could have kept the 1.7L injectors, they probably would have and would have enriched the MPS. Most likely, there were some concerns with the injector duty cycle and/or the injection duration under extreme conditions (e.g. cold-cold start in sub-zero conditions). With 2.0 injectors, you don't need to go and do dyno engineering to adjust the MPS to work with the 1.7 sized injectors.

Bleyseng · Bleyseng's Garage

I was with Dave when he did the dyno work. They mostly worked on smoothing the MAP because it had some big spikes in it. That really smoothed the motor operation out and provided an even powerband. Now its as smooth as my Djet car, lol
Of course the dyno guy was trying to set the A/F mix too lean at 14.7 to 1

Geoff

pbanders · pbanders's Garage

Geoff, you bring up a good point - 14.7:1 is NOT the correct mixture with the 914 motor for part-load operation. Something in the range of 13.7:1 to 14:1 works best, and a dyno is the best way to determine this for non-stock applications and setups. Food for thought.

hardflex · 09-26-2003, 03:57 PM

I had forgotten about the 73 2.0's being extensions of the of the 1.7 unit. I'm convinced. 2.0 injectors it is.

Thanks for the help.

Bleyseng · Bleyseng's Garage

Yes, and the WOT A/F mix is about 12.8 to 1 otherwise you will drop those valve seats out in no time!! If you run it hard at the track, AX or even spirited driving (streetracing) take the time to get it right.
I hate to say it , but look what happened to Zeke at the track!!!

Actually, the 73 2.0L MPS's I have tested run pretty rich too compared to the 74-76 units.

Geoff