Can I put larger pistons on a 1.8 ltr w/ stock EFI, Max piston size for L jetronic 1.8 liter Options

[pnewman]

I was considering doing a head job and changing the pistons and cylinders on my 1.8 liter while I have it out. (IMG:http://www.914world.com/bbs2/html/emoticons/huh.gif)

What are the oem cylinders? 70 mm? I have seen people peddling "94mm" I am not looking at doing dual carbs right now. (IMG:http://www.914world.com/bbs2/html/emoticons/screwy.gif)



Can I go larger and still use the stock L jetronic Fuel Injection system that I have kept well maintained over the years?

[bd1308]

teh limit is going to be your heads....your fine with the larger pistons.

the 912E was an example of a modified L-jet system to fit a 2.0

it's more expandable than D-jet in some ways...dont go wild on the cam though.

b

[McMark]

Just make sure you get the correct pistons for your setup. There are different wrist pin heights.

[r_towle]

stock bore is 93 mm for the 1.8 liter.
Stock bore is 94mm for the 2.0 liter...

rich

[Bleyseng]

You can run the larger 96mm ones but get the right wrist pin height for a 66mm stroke.

[pnewman]

How much will be gained by upping the oem 93mm pistons to 96mm and playing with the wrist pin height and the heads to match?

vs.

oem 93mm (3mm less) pistons and an oem head job.

and how will my oem L jet system react to the increases? (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)



Also is there a one stop shopping source for a correct match heads and pistons for this set up? any one can do oem, but upgrades require someone with specific backround. (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)

thanks, Pete

[Mueller]

increasing the bore to 96mm gives you a 6% increase in displacement, so....in theory, you should get a 6% increase in power.....

also, the larger bore will give you a tad bit more compression with everything else equal...again a little more power.....

for the heads, I'd just do a stock rebuild, not sure if the money is worth it for a 3-angle valve job or not, but it couldn't hurt...

the 1911 with the L-Jet is a good combo and you'll like it...

for the pistons/cylinders:
aircooled technology,
aircooled.net (?)
your local shop possibly


heads:
LEM,
rimco,
local shop?

[pnewman]

Thanks for the info!

Will those sources if given my info know what the right wrist pin height should be?

Also, A stock head job will be fine w/ 96 mm's?

Thanks, Pete (IMG:http://www.914world.com/bbs2/html/emoticons/aktion035.gif)

[Bleyseng]

For more hp I would send them to Len at HAM to rebuild and install 42x36 valves. Will help to build some hp along with the 96mm pistons.
A cam change would also help esp to cool the oil temps down. (IMG:http://www.914world.com/bbs2/html/emoticons/popcorn[1].gif)

[pnewman]

I am looking into 96mm's w/ stock heads. Again I am trying to avoid converting from oem EFI to carbs.

Can I stay stock fuel w/ 96's and upping the valves?

What adjustments if any would have to be done to EFI and timing to accomodate this increase?

I was told that going to 96mm's I would have to watch the compression? Do they mean stroke> What is stock stroke w/ the 1.8 93mm's 70mm's? Therefore what do I need w/ the 96's?

I was also trying to avoid cracking the case so I am not interested in doing a cam right now.

I really appreciate the input, (IMG:http://www.914world.com/bbs2/html/emoticons/pray.gif)

Thanks Pete (IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif)

[McMark]

Keeping the stock EFI means keeping the stock cam. :puke:

Moving to a better cam can free up as much as 30 hp. (IMG:http://www.914world.com/bbs2/html/emoticons/burnout.gif) But it means ditching the stock injection. Aftermarket injection will take dyno time to tune in well ($500), but carbs can be made to work well with just some "ear tuning". I'm a huge FI fan, but I like anything over the stock FI. Especially if you are looking to gain a little power.

[Mueller]

a cam change would require for most parts a complete engine rebuild, the guy is only looking to freshen up the top end......


your engine specs should be:

93 bore X 66 stroke
7.3 compression

with the 96mm bore, the stroke stays the same, the compression goes up to 7.6

ask for 96mm big bore Piston/cylinder kit for a 1.8

if you go this route, nothing should have to be done to the stock FI, just reassemble the freshened up heads, install the new pistons and cylinders and fire the puppy up and enjoy it....don't expect huge gains, but it should be much better than before if the engine is tired.....

[LouisCypher]

Why not increasing the compression to 8.5 or even 9.0? That would free up some ponies

Louis

[MecGen]

Hi

Got some good advice here, Big bore with fresh heads is a nice combo, without droppin lots of $$$.
Pay special attention to the valve geometry/ heights, this is so important after the cyl have been replaced. Nothing worse then doin it twice.

Good luck with it

Louis, Type 4s need a lot of work to keep the heads on the motor stock, bumping the compression is always a good HP thing, bad head thing. Higher compression is usually saved for the bigger $$$ rebiulds.

Later

(IMG:http://www.914world.com/bbs2/html/emoticons/aktion035.gif)

[Pugbug]

I'd definitely go to the 96mm cylinders at least. Gives you 1911 displacment, and an engine that likes to rev.
I rebuilt my 1.8 last winter to that size, but used a web 86 cam, did a bit of head work, and raised the compression to 8.6/1. with dellorto carbs.
It was an amazing boost in hp in a fast reving engine. Made the car much more fun to drive.
Changing the cam is no big deal, and I think where most of the increase came from, but be aware that if you do change the cam you won't be able to use the stock injection system. Carbs or aftermarket injection is the expensive part.
Too bad the stock cam is such a dog.

[LouisCypher]

QUOTE (MecGen @ Dec 12 2005, 04:10 AM)

Louis, Type 4s need a lot of work to keep the heads on the motor stock, bumping the compression is always a good HP thing, bad head thing. Higher compression is usually saved for the bigger $$$ rebiulds.

MecGen,

what exactly do you mean?

[Bleyseng]

You can raise the compression to 8to1 with the stock cam, with higher it gets too hot. You can use a Jake Raby cam that does bleed off more of the exhaust heat and still run the stock FI plus gain a little hp.
Bigger valves help too as they help increase the efficentcy and bleed off heat out of the combustion chamber.
(IMG:http://www.914world.com/bbs2/html/emoticons/popcorn[1].gif)

[Jake Raby]

That cam goes on end of the year overstock special today! As soona s I can get it posted!

[Cap'n Krusty]

QUOTE (Bleyseng @ Dec 11 2005, 04:03 PM)

For more hp I would send them to Len at HAM to rebuild and install 42x36 valves. Will help to build some hp along with the 96mm pistons. A cam change would also help esp to cool the oil temps down. (IMG:http://www.914world.com/bbs2/html/emoticons/popcorn[1].gif)

L jet hates cam changes even more than D jet. The Cap'n

[Jake Raby]

Yep, but the cams I use for each are more times than not EASIER to tune than the stocker is... They yield a better powerband and cooler heads as well...