SOHC Swap ?

[vwdmc16]

Hello, while my '77 fiat still isnt road worthy, ive pondered about installing a 1300 sohc engine in it one day, my 1800 tc is strong but there is something about an engine that can rev to 11k ( when prepared) that is more fun, yes its nieve but its cheaper than making a Tc rev to the same level, and its all bolt it keep in mind this is just an idea.

anyone heard of this being done? can it work with relative ease?

[manoa matt]

With enough money and fabrication you could fit a wide range of motors. You will need to mate that 1300 to a transmission and make sure the shifter is in the correct location, modifications to the trans tunnel and center console may be necessary also custom motor mounts, custom drive shaft, accelerator and speedo linkages.

Considering all that work and modifications, It will be less of a headache and probably less money if you just properly prep the TC motor. With the right carburation, cams and pistons you don't need to rev to 11,000 RPM's to get the power you want.

[pope]

An F1 engine will rev to over 20,000 and probably fit in a Spider

[So Cal Mark]

that 1300 won't rev to 11000rpm without substantial mods either and the sohc design doesn't make nearly the power that a dohc can.

[vwdmc16]

the small sohc with its tiny stroke, is musch less stressed thatn the longer stroke of the TC so it would be a more durable engine an has much slower piston speed. so yes it takes alot of work for a 11k engine, how about 9k? i want more room between shifts on the track. adding a turbo can make these engines make just as much power as TC

as i said this is an idea and it will bolt up to the stock 124 trans, no modifcation of the tunnel needed thats the point of going with it instead of a totally different powerplant. so i would have to worry about those little things like plumbing and linkages

[So Cal Mark]

so why not build a 1438 tc engine?

[vwdmc16]

well i do have a 1438 on the floor of my garage, but the #3 bore is 1.2mm too large. has 1608 head too for some reason


anyway the 1438 has 71.5mm stroke whereas the 1100 has a baby 52mm stroke. its simple physics, the the small stroke engine has far less leverage and stress in the crankshaft and the pistons are traveling 65.7% of the speed of a 1800 at 9k

[lanciahf]

Neat Idea, I always missed the rev-abilty of my old X1/9. There was nothing like that engine, a TC is so rough in comparison.

Since the SOHC engine has both the intale and exhaust ports on the "passenger" side, the drivers side will have a lot of room for your turbo.

Also early spiders weigh about the same as later x1/9s. So no weight penalty here. If it were me I would choose a early spider and a 1500 X1/9 FI motor. For the Turbo, run a pipe from the exhaust manifold to the drivers side engine bay, then you can plumb the turbo to the stock FI intake manifold fairly easy.

Another plus: since the SOHC motors make less torque the tranny and rear end should last longer. Also the front end will be lighter. I am starting to see your line of thinking.

Are you sure the engine mounts straight to the 124 tranny without any problems?

Please keep us posted!!!!!

Ralph

[brad131a4]

Why waste your time on the 1300 just stick a 13b in it and you can rev the piss out of it. Even if you did get the 1300 to rev that high it would be like driving a dirt bike on the road . Power range would be very small and very unstreetable.

[vwdmc16]

good points, getting a good cam would be tricky, but i have full and free access to a mustang dynometer.

finally somebody likes my idea, now correct me if im wrong but the 1500s have a larger stroke? 63.9 or 67.9 depending on generation. for bolting on, many people install TCs in X1/9s with the stock trans so they have the same pattern, just at a different angle.


as for a 13b swap, mmm nah, im not a rotory guy. now its kinda ironic that i bult Rx7 race cars for a living. they take so much fuel to get going and i just dont get a good vibe from them ive never come across one that just runs tops, they all had faults and when they blow a seal they cost 2k to rebuild. if i keep my '91 rx7 i may just install a UZ1 v8 from a lexus.

so nobody still has heard of this swap done?

[SpiderHead]

The Fiat DOHC is usually swapped INTO things, not out of them.. lol

Its so light, torquey, and high revving...

Might as well but a Hyabusa (spell check please..) motorcycle engine in it if you want something else..

-Ryan

[brad131a4]

Now the v8 swap into a 91 rx7 would be nice. Might even be cheaper than rebuilding the stock rotary. I see that you like to fabricate things .If I had access to racing hardware I'd go with a supercharger turbo unit as what lancia had in their rally stratos car of the late 70's early 80's. Supercharger for the low end grunt and a big turbo for the top end speed. That would give you more than enough power to spank just about anything stock on the street . Keeping it together is another story. I had a 1608 build back in the early 80's in a coupe that would run around 9k all day . Not that it had anymore power but sure sounded like a banshee coming down the road. I'm working on a turbo for my spider. I'm using dual downdraft throttle bodies and a medium sized turbo that will give me about 240 horse without having to crank the pressure up to high. This will give me a nice power to weight ratio for the street and keep things from going boom. The main problem is finding out what turbo will work in the rpm range that is most beneficial for the street.

[vwdmc16]

man if i had a twin charge set up from a group B rally car of course id run that, ooh that gives me chills think about all that power. im not a millionaire, cant afford one

what all did you change interally on that 1608?

[brad131a4]

I can't remember exactly what I did. I do know that I spent some change on the rods. I went with some carillos as I remember having to send them dimensions. I used the stock pistons and crank . Had the crank knife edged and everything balanced. The head was ported and the exhaust end was polished. I had a 4-1 header into a 2" exhaust out the back. The intake was dual 40 idfs with the waffle intake. All the ports were matched and the runners were smoothed out. The only thing I didn't change were the cams as they seemed to be pretty aggressive as is. I had some friends that were into 510s at the time and I could smoke them all. I even surprised a few american iron now and then. That sucker flew . I had front springs from a camero in it and the front springs in the rear. It had bilstien sports on it ,that's when you could get them back then. I had some other things for handling which were sketchy at best but did the trick. Thing was flat out scary in the rain just never enough traction with the light rear end. With the things I know now man I could really make that sucker fly today. It came to it's demise when a ball joint or something broke going into a turn and sent me into a telephone poll. The motor wasn't even salvageable as it broke the cam pulleys and busted just about everything in the motor . I did get the rods and crank out and sold them to some racer to get another one.

[mdrburchette]

Dang Brad, great story. I'm sorry your car met such a terrible death and hope you didn't get hurt.
I'm not sure what you're wanting from your engine, vwdmc16, but Brad's story proves you can have a lot of fun with a tc engine. My 1608 is a stout little motor with custom rods, pistons and clutch. When I had the 5" racing clutch and flexplate in it, it would break traction in 3rd gear and revved like a motorcycle. I ended up installing another racing clutch and flywheel in it to make it easier to drive in town, but when I autocross it, I hit 8 and 9k rpm all the time with no problem. With the custom rods and pistons, I lost 2.5 lbs of internal engine weight and lost at least another 10 lbs of rotating mass with the clutch setup.