DOHC 2.0 Conversion; What Do You Think?

Old Fiat Driver said:
As to power the modern engines are much better but a turbo completely solves that. 250 to 300HP or more is no problem with modern electronics.
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Although to be fair, the same treatment on the Honda (or similar modern engine) can yield 600 HP. But as you say, getting that to hook up is another issue. I think the real deciding factor (beyond nostalgia) might be what Old Fiat Driver said about availability of parts; twincam stuff might actually be harder to get and more costly...don't forget it's not just the engine but the trans also.

Hasbro, I'm not into Hondas but I've often wondered what you suggested - why not use the "B" engines. If I'm not mistaken they are easier to get and for a lot less money, and they will make great power for a X transplant (I don't see the need for 300+ HP in this car). But I've also wondered the same question with other engines, like the Toyotas Mark mentioned. Funny how the Honda K became the 'go to' choice.
 
Hasbro, I said I helped Alex put the Honda 2L in his X. Actually it was a 2.4L Honda. It went to Australia and the new owner supercharged it. It ran well before the supercharger but I never drove it with the supercharger since I am here in Socal. The axles had to be made and there were a few mods to the engine as well like hotter cams, headers and computers. The engine dynode out at 250 HP, as I remember, at the rear wheels. I wish I could remember the torque numbers since that's what accelerates the car and horse power just sells the car. As to the Fiat 2L turbo with 12 PSI, there is more power, torque, than you can use on the street and the drivability is just fine probably because of the Fuel Injection. Either way power is more than enough but the modern engine looks really good, car show ready. Also the Honda tranny is a nicer smoother shifting unit and is available in a 5 or 6 speed as I remember. I agree with Dr. Jeff that anything over 300 HP is over the top for the street. Keep in mind the car only weighs from 1900 to around 2200 for a street car so the power to weight ratio is quite good. Also keep in mind that 300 HP will require a limited slip, available in the Honda and hard to find in a Scorpion Transaxle. I completely went thru my transaxle with many new parts and it shifts great with no grinding and does have a ZF limited slip that you don't even realize is there except it just hooks up and goes. Also the Scorpion transaxle is a beef cake, parts are big and strong which is probably what makes it shift a bit slower than the Honda. In my case the Fiat makes sense considering I already have it and the parts are in excellent condition, it's a personal decision but it's fun either way.

keep revin
Charlie
 
I've always found the stock brakes on my 85 X to be very good. Tires are the limiting factor and granted I don't run high performance tread, or track the car needing repeated max brake power. I just think those that knock the stock brakes must have some maintenance issues.
 
bruakeman said:
I just think those that knock the stock brakes must have some maintenance issues.
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While I get what you are saying, not necessarily true. I believe the intent of the statement about the brakes needing to be upgraded was in relation to having 300HP performance potential in the car. Any time you add that much acceleration and speed advantage, you would be foolish not to add an appropriate amount of stopping advantage. It's nice to be able to go fast, it's even nicer to be able to stop. Not criticizing, just clarifying.
 
The problem with the stock brakes is that the fronts lock up way too soon. They want the front to hit the wall first. I replaced the rear calipers with the scorpion/ 125 calipers and put a proportioning valve in the circuit to transfer some braking force to the rear and a few other minor changes. That makes a dramatic difference. If you are using it as a street car there should be no problem. I autocrossed for years, 70 MPH and down, and never ran out of brakes but if you intend to run higher speeds like road racing or track days then more goodies are needed. At any rate at street speeds they will work just fine no matter the HP that is if you keep it down to street speeds, if you don't then that's another story. All this talking has given me the bug to get the conversion done so I started today. It will take a while but the idea is to make minimal cuts and metal removal while trying to keep the engine compartment as close to stock as possible. I am making a few changes like removing a small portion of the rear fire wall and using a 1979 panel to cover the hole just like a 1979 or later x has. This will make it easier to work on the exhaust side of the engine. Also since this is a 1974 I need to create some space on the left beam above the left rear well for the transaxle clearance just like the later 5 speed x has. Does anyone know what material Fiat used for the seal around the rear panel that covers the hole between the engine compartment and the rear trunk.

Getting dirty
Charlie
 
Charlie, any chance you could photo-document your conversion and post it here? I am assuming what you are getting started on is a TC-into-X project, correct?

Pete
 
Right Pete, it is the 2L conversion. Here are some pictures of the before and I'll keep up with the after pictures probably around Sunday or Monday. This is the engine combo I started with and the drive train is now removed. This was an autocross engine and a 5 speed tranny, their gone now.

Charlie

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Done this conversion twice.

Don't bother unless you intend to build the engine to around 150 at the wheels... the cost to do this is relative to how much you are able to do yourself, and how much you get the component parts for... for example things like camshafts are very pricey when purchased new, not so bad if you find them as a good used item...if you want to buy something NOW...then it will obviously cost more than f you wait for the bargains to come your way.

Search Xweb version 1 ... I did quite a long write up back when I did the research for my first conversion.

Use the Monte shift linkage assembly in its (almost) entirety, simplest way to get it right.

Cutting bodywork... there is just one cut you NEED to make, that's to the LHS chassis rail for transmission clearance...drill out the brake pipe mounting bracket so you can shift it, as it's right where the cut goes. There is absolutely no need to cut any of the firewall or bulkhead.

I have made a couple of changes along the way, but the basic install is the same. Initially I mounted the engine with a 10 degree rearward tilt... i.e. less tilt than the 20 degrees that the Lancia engine leans backwards, like this my engine was positioned with everything ahead of the centreline of the strut towers. IMO this still has too much rear weight bias. I have since re-engineered the engine position to have it with a 10 degree FORWARD tilt...and fitted a cylinder head from a post 1986 8valve DOHC engine...the heads on these later DOHC 8valvers is "reversed" on the block, so the intake is now to the rear of the engine and the thermostat / water outlet is down at the transmission end, which makes the install quite a lot neater and simpler...

Now before someone bleats on about "we never got those heads in the USA" well we never got those heads (much) here in Australia either... but they are available new ex europe at not a horrendous cost so I bought a brand new one and found some camboxes and covers in New Zealand...plenty of performance advantages with the later style heads as well... bigger intake valve, larger seat throats, much nicer combustion chamber shape, only two oil up holes as standard ... and if you chasing around 190/195 crank horsepower, you WILL need the larger valve and seat throat...the smaller combustion chamber allows the use of a smaller piston dome, again something you NEED to have to make the power your after with just 8 valve and no variable valve timing.

If your after more power than this then the 16 valve head from the later Fiat engines does fit the early style 8 valve block... and with the engine tilting forwards is an option and it will fit...New 16 valve cylinder heads are available ex europe for around 800euro with valves/springs etc but no cams or oil spray bars. Building a 16 valve engine naturally aspirated to around 235hp at the crank isn't that difficult with the right combination of quality parts ... if you want to go absolutely crazy there are kits available to build a turbo 16 valve (as per Lancia Delta Integrale) right up to 750/800hp ... with no variable valve timing...the stock Beta transmission wont like anything much over 350/400 though...as the torque will push the cluster and primary shafts apart, and the trans casing end support cracks. (but there is also a fix for this if you ever get to that stage)

I would never consider any engine other than a Fiat in any X19 (or any Fiat / Lancia) that I build, as I'm a Fiat guy to the core.

SteveC
 
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So much good info here. I honestly believe I could enjoy just about any of the motors discussed here. To reiterate, the lbs/whp goal for this project would be between 10 to 12 lbs/whp. Total weight would be as light as possible . I know it's hard to get down below 1800 or 1900 lbs. but it's been done. There's a sweet 1,518 lb. X from Down Under that I really admire; https://t124.com/forum/forum/fiat-fans/fiat-fans-aa/14314-track-day-x1-9

With Charlie and SteveC piping up I'm encouraged to give it a whirl as I can have most of the 2.0 stuff needed so initial cost would be much lower. I did say initial. Whatever conversion it will be will be costly one way or another. I'm not in a rush, either so I can attempt to do what I can and outsource when I have to. If the motor takes a long time I have the rest of the X to work on. Steve, I do remember reading about your changing the angle to 10 degrees forward.

Pete Whitstone is the seller and has been great to work with. There are a lot of pieces parts to go through and I'm having a blast figuring all of this stuff out. Thanks for your patience, Pete!
 
Hasbro said:
it's hard to get down below 1800 or 1900 lbs. but it's been done
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At a cost. Beyond a basic level, every pound you reduce gets more and more expensive to achieve.


Hasbro said:
I can have most of the 2.0 stuff needed
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Does that include the trans, shift linkage, etc? If not then those will get expensive to find.


Hasbro said:
Pete Whitstone is the seller and has been great to work with.
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You are in great hands. You can trust him fully. :)
 
Dr.Jeff said:
At a cost. Beyond a basic level, every pound you reduce gets more and more expensive to achieve.



Does that include the trans, shift linkage, etc? If not then those will get expensive to find.



You are in great hands. You can trust him fully. :)
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My two passions to obsession when building a car are suspension and weight reduction. I'll get her way down. I've had two street cars under 1400 lbs and four under 1600. The 2.0 is heavy but it should be a blast.

Pete doesn't have everything but most of it.
 
Hasbro said:
My two passions to obsession when building a car are suspension and weight reduction.
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Apply your obsession to the engine components you use and it will be worth the effort. My engine uses all factory parts... cast pistons, OE forged rods, OE forged crank, OE steel flywheel, OE valves ...but each item has been meticulously prepared and lightweighted, i.e. the crank has had almost 4kg removed from the counterweights... the only items not made by Fiat originally are the camshafts. It revs to almost 8k very easily and quickly and behaves a lot more like it's little brother the 1756, but has loads of torque throughout the rev range.

The parts ARE available...and relative to other car make parts prices are not too expensive... sure you might not be able to get a glossy catalogue from some rice boy racer shop to pic and choose all the parts from one source...but they can be bought without having to sell a kidney. People who say Fiat engines are expensive to build haven't built many engines... they ALL get expensive to do properly.

It's unfortunate that most people won't compare apples to apples... the USED K series engine they buy for a conversion is exactly that ...USED.. the engine you'll build for a Fiat DOHC conversion will be all new. When it comes time for the K series crowd to rebuild their K20's in a few years time, they wont be too happy that their 1k used engine all of a sudden presents them with a 10k rebuild bill. The initial cost of the engine and transmission in a K20 build is a tiny portion of the final cost, and very few (if any) builders have been brave enough to itemise the real TOTAL cost of their conversion.

SteveC
 
Hi Steve, I also have done this conversion twice before. This engine is way over 150 HP so were good there. I do like the idea of the later reversed head but my head is already built so I'll stick with for now, maybe change later. On my first conversion I used the Scorpion tranny linkage and found it lacking so I built a cable shifter and I really liked it but am now modifying it for some further improvements. The only changes I am making to the rear fire wall is essentially updating it to the later x's with the removable panel for better access to the engine. I have measured the bottom of my oil pan to block and find it's 15 degrees not the 20 you mentioned, are we talking about the same thing? At any rate I'm pushing ahead and hope to finish before the end of the year.
Cheers
Charlie
 
If you are looking for a faster track day type car then the standard engine is rather limiting in that respect and so some sort of more powerful engine is required. However, it is often over looked that higher % gains per monies spent can be had in the lap time area by sorting the brakes and suspension, something you should certainly do anyway if you are heading north of 150hp
 
Speedy Fiat, now there's a name, my racing days are over. This is just a project for an old guy that already has all the parts.
Have a great one
Charlie
 
Or if you just want to have fun driving at the limit, then keep everything stock and mount very skinny, really hard compound tires. Makes it feel like you've got 500 hp to handle; tire spin on acceleration, drift when cornering, lock-up on braking, etc. Maybe even ditch the muffler and add solid engine mounts so it sounds and feels like a performance car. All the visceral impact of going fast while actually staying within the speed limit. Now go take on that school bus at the stop light! :)
 
fiatfactory said:
I have made a couple of changes along the way, but the basic install is the same. Initially I mounted the engine with a 10 degree rearward tilt... i.e. less tilt than the 20 degrees that the Lancia engine leans backwards, like this my engine was positioned with everything ahead of the centreline of the strut towers. IMO this still has too much rear weight bias. I have since re-engineered the engine position to have it with a 10 degree FORWARD tilt...and fitted a cylinder head from a post 1986 8valve DOHC engine...the heads on these later DOHC 8valvers is "reversed" on the block, so the intake is now to the rear of the engine and the thermostat / water outlet is down at the transmission end, which makes the install quite a lot neater and simpler...
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Interesting how the timbre of this has shifted :)

A couple of questions:

How did you shift the tilt of the engine @30° on your, from 20° back to 10 degrees forward?

Would a Ritmo Abarth 130TC transmission be a better place to start given the engine on those cars is bolt upright or is that just a different can of worms? I know the shifter mechanism is to the rear but with cables or judicious linkage this seems resolvable.

I note that the Chroma had a distinct forward tilt to the twin cam engine in it, is this an option? Or is this engine family verboten or impossible to fit?

Thanks

Karl
 
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