Technical 16v Bottom End 8v Head

[fatty]

Will a 8v head fit onto the 16v bottom end? I've been doing a little bit of reading up and the 16v apparently has a stronger crank. Is this true and will the head and block work together.

Just building an NA engine in my head haha

 

[Oldschool]

The 16v conrods are weaker than others.

The crank isn't stronger.

You will need the late 8v cam pulley if it vis an earlier head.

 

[Steffen Jensen]

The 16V buttom is stronger then the 8V.
You have stronger berings and a "reinforcement" between the berings.

The 8V head is best for tuning, it´s possible to get a lot more rpm then the 16V.

Im building a race enigne with a punto1 85 16V bottom, 1368cc crank and a punto75 head.
Until now, no probs fitting it together...

 

[fatty]

So could the reinforced bearings be used with 75 conrods? (I don't know much about the workings of an engine) Which I presume are stronger than the 16v ones? I assume using the 1368 crank will increase the stroke? Will the crank benefit much from some lightening and balancing?

In my head I'm wanting to build a 1242 that will Rev to 8.5k safely, with a lot of head work and a decently lifting road/race cam and a set of ITBS and DTA management. Whether this will acctually translate into what goes into my car is debateable but its what I'm aiming for.

 

[Oldschool]

What is your aim?

Rather than messing with throttle bodies I would go for a proper inlet manifold, plenum chamber and a single throttle body.

On the porting side you can't do to much because the walls are too thin.

Slightly larger valves are possible and high compression will be a must.

Exhaust system is crucial to achieve power, which needs to be calculated.

 

[fatty]

Don't really have an aim......Just a well built NA engine.....something a little different to everyone going turbo. So a Large Single TB will be better than a set of 4 ITB's?

 

[Oldschool]

Don't really have an aim......Just a well built NA engine.....something a little different to everyone going turbo. So a Large Single TB will be better than a set of 4 ITB's?

Bottom end power will be much better and you can come very close top end.

Over all I consider it the better solution.

If you want to have an outright race sat-up things are abit different, but then the whole engine needs reworking on a scale that is out of reach for the likes of us.

 

[fatty]

No plans for race engine just a well sorted NA road engine. What size Single TB do you reccomend? Also what kind of exhaust? A 4-2-1 Manifold is best for bottom end tourque I believe? I don't want a loud system, something I can use everyday.

 

[Steffen Jensen]

Im going for 4x 40mm TB´s...
High compression is made by costum made pistons and rods.
The size of the pistons is minimal to reduse wight, and longer rods are made to recive high compression.
Thinking about a C&B 300 cam, and rpm´s to about 9000 with trible valvesprings.

 

[fatty]

Thats quite some spec!! What kind of power and more importantly tourque are You hoping to get from that? What is the engine going to be used for? Road car?

 

[Steffen Jensen]

Road car ad first... but only few days a year.
do not know the power, but hoping about 130-140bhp.

The engine projekt stands still ad the moment, is building the car now.
mounting roll cage and rebuilding the car.

 

[fatty]

Well thats a pretty awesome project!!

 

[fingers99]

I did catch sight of a SuperFire 8v engine in the scrappy (I tried to buy it but "the guy who always buys the decent engines" already had his moniker on it and wouldn't let it go ). It looked to have the same tougher bottom end as the later 16v engines.

Otherwise I'm with OldSchool. Having said that, I've seen videos of both Nitrane's 8v and that SilverSei with the Hyabusa TBs at Cadwell and Nitrane's car looked to be a bit quicker. I've lost the Silver Sei vid or I'd put a stopwatch on it!

In any event, 8v tuning parts are going to be a lot cheaper.

 

[fatty]

Yeah i've read that the 16v engine is a non starter dude to the limited cam choice and hydraulic lifters so its actually worth going for the 8v which can rev higher

 

[cc1]

Fatty;
I believe the newer CF2/CF3 1242 8v engines use the same bottom end as the 16v with the fifth bearing latice.

 

[Oldschool]

Im going for 4x 40mm TB´s...
High compression is made by costum made pistons and rods.
The size of the pistons is minimal to reduse wight, and longer rods are made to recive high compression.
Thinking about a C&B 300 cam, and rpm´s to about 9000 with trible valvesprings.

40mm throttle bodies are far to big for this application. You will be much better of with about 32mm.

And you won't need any more than double valve springs.

 

[Brooky]

40mm throttle bodies are far to big for this application. You will be much better of with about 32mm.

And you won't need any more than double valve springs.

Can you supply these for the 16v engine, as i might be in need of some me thinks

 

[Oldschool]

Can you supply these for the 16v engine, as i might be in need of some me thinks

Springs or throttle bodies?

 

[Brooky]

springs, ive got the throttle bodies

 

[Oldschool]

springs, ive got the throttle bodies

They should be available from Fiat. The early 16v used to have double calve springs before some wrotten bean counter decided to down grade again.