1800 pistons vs 2000 stock pistons

Tech chat w/ Marc Matzer
Marc
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1800 pistons vs 2000 stock pistons

Post by Marc » Wed May 04, 2011 7:45 am

If you want to up the compression in a 2000 engine,you can use stock 1800 pistons.They are both stock at 84 mm.The difference is the size of the flycuts in the top of the pistons.The 2000 has much larger flycuts than the 1800 pistons.This should bring your compression up to 8.9 to 1 in a 2000 engine using 1800 stock Fiat pistons in a 2 liter block.

rpconlon
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Post by rpconlon » Wed May 04, 2011 10:45 am

Two questions:

Does this make the engine interference?

What about 1800 pistons and 1800 head?

Thank you
Ron
Ron Conlon
2016 Fiat 500 Sport
Ottawa, Ontario
Canada

Marc
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pistons

Post by Marc » Wed May 04, 2011 5:14 pm

Yes it makes it interference as with all piston upgrades on a 2 liter.There is no difference in the combustion chamber sizes on an 1800 and 2 liter head.I have measured them both and are the same.

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Ron
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Post by Ron » Thu May 26, 2011 12:09 am

"...to up the compression in a 2000 engine,you can use stock 1800 pistons ... This should bring your compression up to 8.9 to 1 in a 2000 engine using 1800 stock Fiat pistons in a 2 liter block."

WOWSER, HOWSER!
:dontknow:
If that be the case, and valving & head design are similar, what makes the 1800 head a power booster when installed on 2 Liter blocks?
Doesn't THAT raise compression to 8.9 : 1? . I missed or mis-read some stuff.
I bought a 2000 assembly and 1800 head to combine into a nice little Italian hot rod.
:shift:
77 124 SPIDER , 82 DATSUN 720 DIESEL SD22 , 81 TOYOTA HI-LUX , 64 CORVAIR MONZA

Cmdr.Ron
I am swamped in Blessing!

Marc
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1800 head vs 2 liter head

Post by Marc » Tue Jul 26, 2011 9:25 pm

Ron,
That's a Fiat Twin Cam Myth,the combustion chambers sizes are the same.
A 1608 and a 1438 are a tad smaller but can't be used on the bigger engines.
1800 pistons will up the compression slightly in a 2 litre block because of the smaller fly cuts.
But why bother to even do that...just install 9.8 to 1 pistons,the torque difference is dramatic over stock.

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Ron
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Post by Ron » Wed Aug 03, 2011 11:47 am

Ahoy there, MARC...
:whatthehell: Since I've obviously fallen for the Hog Wash & Hoo-Doo, would you please correct me?
- Would this mean the advantage of switching to a 2L is merely displacement?
:read: Artigue's work sets things straight on induction, but I've lost the trail on that Brit race engine builder. What' his name? Guy something?
- Be there a "Sticky" on FLU Fact vs. Fiction of Fiat Twin Cam Building so those of us without decades of dabbling in Fiats can learn what combinations work before assembly?
- I can't possibly be the only one misled, or it would not be myth.

- Not trying to be a "Thread Buster", but I discovered after 70,000 miles that my Datsun 720 has a similar situation with the Transmission Lube thing. Gotta eye that thread.
:popcorn: THANK YOU, Marc!
77 124 SPIDER , 82 DATSUN 720 DIESEL SD22 , 81 TOYOTA HI-LUX , 64 CORVAIR MONZA

Cmdr.Ron
I am swamped in Blessing!

Marc
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Haeds and Pistons

Post by Marc » Mon Aug 29, 2011 5:08 pm

Yes Ron It really is a myth.I used to think the same thing,I will take some pictures to show you the difference between the two piston types.A 2 litre engine has a longer stroke(90)vs (79.2)mm in the 1756 engine, same 84mm bore.A 1592cc head does have a slightly smaller combustion chamber and is a sister engine to the 1756,1995 cc engines and is a bolt on head.The 1438,and 1608 engines have a different offset bore spacing and can't be used a 1592,1756,and 1995 engine,although they have slightly smaller combustion chambers.Nothing like cubic inches,a souped 2 litre engine will produce more torque than all the other engines.
Call Midwest Bayless and ask them the same question...I will try to shed some light on myths...Think I am going to start a Mythbuster section here.

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Re: Haeds and Pistons

Post by vandor » Sun Sep 04, 2011 11:33 am

Hi Marc,

I have measured both the 1800 and 2000 combustion chambers, as have many others. The 1800 is ~47cc, the 2000 is ~53cc. I am wondering if you have measured the wrong head?
If you put a 1800 and 2000 heads side by side the difference is plainly visible, the 45 degree cutouts on the sides of the 2000 combustion chamber are much larger, giving a smaller squish area (area that is flat against the piston).

Yes, the 1438 and 1608cc engines have a different bore spacing, BUT the 1592/1756/1995cc heads have the same bore spacing, amazingly, as the earlier blocks/heads. I have no idea why. Because of this the valves are not centered on the pistons in the #1 and #4 cylinders on the 1592, 1756 and 1995 engines. The early heads can be used on the late motors if the front water passage is modified (welded) to be the same size as on the later engines.

Yes, the stock 1800 pistons would give higher compression in a 2000 engine, but stock 1800 pistons are not readily available new, so that is not really an option for most people.

bye,

Csaba
Auto Ricambi, LLC
124 Spider Specialists
http://www.autoricambi.us

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Post by dougburdick » Mon Sep 05, 2011 2:07 am

Got to agree with Vandor here. I just built a 2lt for my 76 scorp. I have a few 1800 heads in my shop and a couple of 2lt heads. To tell them apart quickly, I just turn them over. The 2lt heads clearly have more volume in the combustion chamber than the 1800s. It's a difference you can see without measuring!

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heads

Post by Marc » Tue Oct 25, 2011 9:08 am

Casting no# 4372291 41.8 inlet valve 36 ex valve (mm) was used on 2 litre and 1800 blocks,unleaded seats.That casting no# I'm pretty sure was used from 76' to 79 1800/2000 cars.
Earlier heads with the the 43.5mm inlet valve will up the compression in 84mm bore TC's and can increase power up to 10bhp in a 2litre engine.That head is casting no# 4462603,1585cc TC,late big valve type.
Anyway, the original post was to alert you to the difference in the flycuts on the pistons.
Problem with measuring the combustion chambers is, were you measuring a late or early style 1995cc combustion chamber?Fiat made the in both an earl and late style which are different in size.See my post on Fiat casting numbers and head valve ,port size and combustion chamber sizes.

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allenlofland
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Old Wives Tails

Post by allenlofland » Thu Nov 03, 2011 2:29 pm

This thread is a good example of honesty gone astray in advice. Before anyone builds an engine that might have the 2 liter 1800 head combination and HC pistons involved STOP and learn what you are doing BEFORE you become another victim. We have several fiats running around that sound like jackhammers in the woods do to CR Pinging that are going to be very expensive to fix becasue of this .
Casting numbers and I did this and he did that just dont get it. Learn before you burn ( your pistons that is )
Compression is fun but it can ruin your day. 1800 heads and 2 liter heads are different but dont take my word for it, learn to CC your own set up BEFORE you bolt it together. :)
Now I got to go change my head gasket, seems my wife's claim that our spider was pinging in the hills last month wasnt just her imagination :(
Allen & Lynette Lofland
Wichita Kansas
Back on Land with Our Fiat :)

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Re: heads

Post by vandor » Mon Dec 05, 2011 8:40 pm

Marc wrote:Casting no# 4372291 41.8 inlet valve 36 ex valve (mm) was used on 2 litre and 1800 blocks,unleaded seats.That casting no# I'm pretty sure was used from 76' to 79 1800/2000 cars.
You are mistaken. There is NO head that was used on both 1800 and 2000 in the US. The 1800 heads had 4 air injection ports with an external manifold, while the 2 liter carburated heads had one or two larger air injection ports. The 2 liter fuel injected head has no air injection holes.

Also, no heads in the US came with 43mm valves - if a head has those, then they were added later. A few models in Europe had them, like the Ritmo 130TC, but it's fairly rare.

Csaba

Marc
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casting No#

Post by Marc » Sat Dec 10, 2011 6:49 am

Csaba,
Your right,in the US.These are Fiat no#s printed from their engineering manual.Those general casting no# were used apparantly for more than one design,different markets etc..Csaba I have a Clean 1592 head on the bench,it looks like the best stock head to use on an 1800/2000.no egr plugs etc...I want to get it built up with bigger valves and seats,ported etc,future plans for a 2 liter block on the stand in the garage.

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Casting #

Post by Marc » Sun Dec 11, 2011 9:27 am

Csaba,
I checked into it,I was not mistaken.It was used in europe,in 1800/2000 series 132 cars!

bigaun
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Re: 1800 pistons vs 2000 stock pistons

Post by bigaun » Tue Apr 17, 2012 11:43 am

[quote="Marc"]If you want to up the compression in a 2000 engine,you can use stock 1800 pistons.They are both stock at 84 mm.The difference is the size of the flycuts in the top of the pistons.The 2000 has much larger flycuts than the 1800 pistons.This should bring your compression up to 8.9 to 1 in a 2000 engine using 1800 stock Fiat pistons in a 2 liter block.[/quote]


Ill go with 2000 stock pistons. I havent tried the 1800 pistons so I guess i have no idea on what the difference are :P

[quote="rpconlon"]Two questions:

Does this make the engine interference?

What about 1800 pistons and 1800 head?

Thank you
Ron[/quote]


Just have that question in mind when i read the title of the thread. LOL

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