Fiat 850 engine upgrade ideas

[dherr]

Been thinking about some upgrade ideas while I wait to get the 850 Spider. As Carl knows, I like to modify cars, and the Spider will likely get some of this along the way. While I would love to score an Abarth 1050 engine, they are a little hard to find and expensive when found. So short of a larger engine, looks like upgrading with forced induction could be an option. Talked with a guy on the GRM forum who had a turbo 850 and also mentioned these small AMR 500 superchargers. Looks interesting and relatively inexpensive.

So combine a supercharger with a Weber DCOE 40 and a 123 Distributor for timing and you could safely run 6-8 pounds of boost. Looks like all the parts are less than $1,500 and my guess is this would be good for 70 HP, so pretty much what the Abarth 1050 puts out.

Keeps the engine compartment reasonably intact, keeps the sport exhaust and header and modifications to the car as easily reversible. Any thoughts on this plan, what am I missing?

 

[johnph]

Been thinking about some upgrade ideas while I wait to get the 850 Spider. As Carl knows, I like to modify cars, and the Spider will likely get some of this along the way. While I would love to score an Abarth 1050 engine, they are a little hard to find and expensive when found. So short of a larger engine, looks like upgrading with forced induction could be an option. Talked with a guy on the GRM forum who had a turbo 850 and also mentioned these small AMR 500 superchargers. Looks interesting and relatively inexpensive.

So combine a supercharger with a Weber DCOE 40 and a 123 Distributor for timing and you could safely run 6-8 pounds of boost. Looks like all the parts are less than $1,500 and my guess is this would be good for 70 HP, so pretty much what the Abarth 1050 puts out.

View attachment 95215

Keeps the engine compartment reasonably intact, keeps the sport exhaust and header and modifications to the car as easily reversible. Any thoughts on this plan, what am I missing?

For road use, any 850 with more power wants to have a longer Ring & Pinion. That is the way Karlo did it.

 

[dnudelman]

Hey Speedracer,
Your 850 stock motor with 50 years on it will give you all the power you need to crash straight into a concrete wall.

You should assume all below are shot and need replacement.
Brake Calipers
Brake Hoses
Brake Cylinders
Master Cylinder
brake reservoirs
front ball joints
Kingpins
A arm bushings
Shock absorbers
Axle silent blocks and boots
Motor and transmission mounts
Coolant hoses
Plugged and/or leaking radiator
Tie rod ends

After all that is done, and maybe more you can play Big Daddy Don Garlits.

Have fun.

 

[dherr]

Yes, understand completely @dnudelman, I build cars all the time and yes, like this Triumph GT6 with a Rover V8, car is all new brakes, upgraded suspension, Subaru LSD rear, etc.... So understand completely that 50 year old car will need to be gone through completely. I am not looking to make this 850 into a rocket, just looking to give it a decent power to weight ratio so it is a little safer to drive. Zero to 60 in 20 seconds is not safe. I don't think 70 HP is going to qualify as a speed racer.

​

 

[dnudelman]

I've heard those GT sixes can get very squirrely

 

[dherr]

The MK1 GT6 has a swing axle suspension, this car is the MK2 with the rotoflex style rear suspension with lower control arms. Completely eliminates the problem and with a Subaru LSD, it can handle the power and have predictable handling. Now back to the Fiat content

 

[fiatrn]

maybe have fun with what you have - - all new gaskets, balance the rotating mass,, get a "bigger" cam and carb. Maybe nab bigger pistons and valves. You can put on a modern alternator for less drag (that should be worth 30hp, right?) and an electric fan and that should be worth another 30hp. Electronic ignition. then go have fun!

 

[Jeff Stich]

You should assume all below are shot and need replacement.

front ball joints

These must wear out a lot, I can't even find them on my 850's.

 

[dnudelman]

These must wear out a lot, I can't even find them on my 850's.

oops, meant upper, lower bushings.

 

[carl]

When I went to dherr's house to get the X I bought from him he was busy stuffing Rover V8s in everything he could get his hands on. His work quality is superior. That DCOE with a baby supercharger is so cute it would make your 850 a real crowd pleaser even if you never drove it anywhere.

 

[dherr]

Thanks Carl, I agree that this would look really cool and I know it fits as it has been done before, this one is fuel injected, I would prefer to keep it cleaner and much simpler with a programable distributor and the DCOE feeding the supercharger, looks like there is plenty of space for it.

 

[ramona300]

Thanks Carl, I agree that this would look really cool and I know it fits as it has been done before, this one is fuel injected, I would prefer to keep it cleaner and much simpler with a programable distributor and the DCOE feeding the supercharger, looks like there is plenty of space for it.

View attachment 95234

That's my engine from a long time ago. Looks different now. If you use an AMR500 I would suggest you use an intercooler and maybe reduce the compression ratio and consider E85 fuel. I have no idea why people use a twin side draught Weber with an AMR500 when a single SU will do a far better job. If you do decide to run fuel through an AMR500 make sure it's a Japanese made unit and not Chinese. I have the injectors after the charger. I suggest you check out my thread. https://xwebforums.com/forum/index.php?threads/850-sport-coupe-series-2-track-car.28768/

 

[dherr]

Well the guy in Australia with the supercharger with the weber adapter does not respond to any communications so I have given up on that route. I have been going down the path of fixing all the mechanical stuff (brakes first), and getting new tires so it is is road worthy while planning on how to make more power. The larger engine path seems like it is not going to happen as there are just too many variables and the speed parts in Europe like a PBS 8 port head are $$$$, so back to a forced induction gameplan. Then this drops on Ebay today.

So a custom stainless steel manifold for an 850 and a rebuilt T25 that has been sized for the 903 engine. Hard to pass this up for $500, will get these parts and plan on how to build a turbo 850. Goal is still modest power goals, so probably use a draw through carb and limit boost to 8 -10 pounds.

 

[johnph]

Well the guy in Australia with the supercharger with the weber adapter does not respond to any communications so I have given up on that route. I have been going down the path of fixing all the mechanical stuff (brakes first), and getting new tires so it is is road worthy while planning on how to make more power. The larger engine path seems like it is not going to happen as there are just too many variables and the speed parts in Europe like a PBS 8 port head are $$$$, so back to a forced induction gameplan. Then this drops on Ebay today.
View attachment 96417
View attachment 96418

So a custom stainless steel manifold for an 850 and a rebuilt T25 that has been sized for the 903 engine. Hard to pass this up for $500, will get these parts and plan on how to build a turbo 850. Goal is still modest power goals, so probably use a draw through carb and limit boost to 8 -10 pounds.

If that engine makes so much power that you rip teeth off the pinion shaft, I have a Hewland Mk9 five speed for sale. It has a Quaffe limited slip diff and Hewland Mark 5 shafts and internals so it is good for 240 hp. $6000. It comes with a nice wood box with 7 spare gearsets. R & P is 9:31

 

[ramona300]

Well the guy in Australia with the supercharger with the weber adapter does not respond to any communications so I have given up on that route. I have been going down the path of fixing all the mechanical stuff (brakes first), and getting new tires so it is is road worthy while planning on how to make more power. The larger engine path seems like it is not going to happen as there are just too many variables and the speed parts in Europe like a PBS 8 port head are $$$$, so back to a forced induction gameplan. Then this drops on Ebay today.
View attachment 96417
View attachment 96418

So a custom stainless steel manifold for an 850 and a rebuilt T25 that has been sized for the 903 engine. Hard to pass this up for $500, will get these parts and plan on how to build a turbo 850. Goal is still modest power goals, so probably use a draw through carb and limit boost to 8 -10 pounds.

Which guy in Australia would that be? If you are referring to me what do you want to know? Turbo chargers on 903cc engines have not been successful locally.

 

[dherr]

Hi Graham, not you unless you run https://joeblow.me/ who does the AMS supercharger kits for VW's that I was looking to adapt to my 850. I have some friends on GRM that have successfully turbocharged the 850, so will be following their recipe.

 

[dnudelman]

Hi Graham, not you unless you run https://joeblow.me/ who does the AMS supercharger kits for VW's that I was looking to adapt to my 850. I have some friends on GRM that have successfully turbocharged the 850, so will be following their recipe.

You realize that alot of 850 conversions ran Fiat 124 push rod reverse rotation or 1600 TC with VW transaxles?

 

[JimD]

 

[ted83x]

Has anyone looked into using a motor cycle motor? Most are difficult to separate from the bike trans, and using the bike trans instead of the car trans has some benefits, but no reverse gear.

I was recently doing some work on a BMW K75, and the motor separates from the trans and it actually uses a clutch similar to a car clutch. Looking at on-line pictures of the BMW motor, it has a bell housing that would have to be retained and modified. The alternator mounts to the motor bell housing.
If it could be adapted, 75 horses and could be lighter. Also they seem to be fairly cheap. Not a super high RPM bike engine, but 8,000 RPM in a car would be ok.

 

[Dave Bassett]

There are several videos on Youtube in which BMW 1200 cc engines have been installed in Sunbeam Imps. Apparently, there is an outfit in the UK that manufacturers a bell housing for this application. These videos might be of interest.