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Yeah, I know the single port heads hold em back, but I wonder if some people could shed some light on what the F-Vee guys do to 40hp motors in their cars. Also some rough power and rev figures would be heaps helpful.

Other questions;
A 69mm crank and rods would drop straight in right?
How much boost would this sort of motor take do you think? (stock crank/rods/pistons)
Any one here EFIed a 40hp or 1300?

would you be staying with single port?

For now anyway. Yes. Staying with the single port. Unless I could track down some twin port 1300 heads that is.

stwitching to twin port will make EFI and Turbo EFI alot easier! is why i say

the cranks will drop in, i'm using a 82mm crank in my late dual relief 40hp case, but then there not a 40hp.

the thing that makes a 40hp is the crank and rods(and pistons i guess) and the thing that makes the weak link is the crank....

i guess you could de stroke a nice CW 69 maybe?

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http://scca.cdn.racersites.com/prod/ass ... nuary3.pdf

"40HP" heads do have siamesed intake ports, but that's where the similarity to "singleport" (1300 or 15/1600SP) heads ends - the valves are different sizes and the intake ports are totally different.
1300DP heads are essentially identical to 1600DP heads other than the bore diameter and the chamber volume (they both use 35.5 x 32mm valves - 35.5s do not clear the cylinder walls of STD or +.5mm 77mm cylinders at high lifts). If you want to build a Frankenstein 1200DP there's no need to hold out for 1300DP heads, simply step-cut some 1600DP heads to fit the 77mm cylinder O.D. You'll need some odd-length head studs, but that's trivial stuff compared to some of the other weirdnesses you'll encounter.
40HP rods are wider than 13/15/1600 rods (same bearing shell, but the journal's wider) - a 1600 rod would have gross sideplay on a 1200 crank, not to mention 22mm vs 20mm wristpins. 1200 and 1300 pistons have the same diameter, but that's all...compression height and wristpin size are different. 64mm cranks are also flimsier and more prone to flexing/self-destruction at high RPM than are 69mm cranks.
Late-model 1200 cases are essentially identical to mid`72/`73 AE 1600DP cases other than the oil cooler hardware size and the center main web beef (they use special 77mm cylinders that look like short 1300 jugs, same O.D. on the bottom as 15/1600, so a `69mm crank & rods will drop in (note that late 69mm cranks have thinner cheeks adjacent to the center main to allow the web to be thicker - an early 69mm crank may require some clearancing of the center main web of a late case.)
40HP rods are WEAK - IMO it'd be folly to boost any engine fitted with them more than a "little", such as you could get away with using an old Judson supercharger...let's say no more than ~70HP before self-destruct.
If you use a 69mm crank and rods, it's basically not a 40HP anymore so the point is moot.

FV motors were subject to rigid technical inspection; anything 100% legal was essentially just a bone-stock 40HP built to the limits of the factory spec tolerances. Back in the day it was common to acid-flow the intake manifolds, install the pistons upside-down for a tiny improvement in rod angularity, and spend inordinate amounts of money on "cheater" heads that were tweaked as far as could be hoped to (usually) pass tech inspection. Over the years, as these tweaks were detected, the rules were written to specifically outlaw them.
If you want a strong "stock" 40HP, use the heads found on later "D" engines sold in other countries. Late `65 US-market 9xxxxxxxxx motors had these same heads - they still have the same tiny 32 x 30mm valves as the earlier 40HP heads, but the intake ports are better.

So, what you are saying is... in more words, "just build a 1600 and turbo that". Right? Which makes sense. Thanks for indulging my dumb questions.

A 1641 will do...
viewtopic.php?f=3&t=137146&start=392

(I'd probably go thickwall 88s and WBX 1.9 crank if doing a small T1 turbo motor---are the good 88s still available in A pin height?)

wally got good power from a turbo 1200

petew wrote:So, what you are saying is... in more words, "just build a 1600 and turbo that". Right? Which makes sense. Thanks for indulging my dumb questions.

Pretty much. Unless you're subject to rules that limit displacement (or require vintage external appearance for some reason) IMO it's pointless to work with antique parts when better/stronger ones are so readily available.
69mm engines are ~½" wider than 64mm, so increasing the stroke undetectibly requires special pistons or connecting rods.
I once built an 83x69 "40HP" using narrowed 1200 rods and big-bore 40 pistons in 1500 cylinders. It did get better mileage than a "normal" 1500SP, mostly due to the smaller heads (at the expense of losing at least 500 usable RPM off the top) and perhaps helped by the lighter components, but the "stretched" intake manifold and sheetmetal were evident to anyone who knew what a 40HP should look like. An interesting project, but more trouble/expense than it was worth.

Marc wrote: 40HP rods are WEAK - IMO it'd be folly to boost any engine fitted with them more than a "little", such as you could get away with using an old Judson supercharger...let's say no more than ~70HP before self-destruct.

Hey Marc,
Not that you're not right (you are as they are/look weak), but, like Andy mentioned, we have a dyno contest each year in Germany who builds the strongest 1200 engine, n/a and turbo class and I boosted the snot out of my build 40hp engine and got 155 WHP or 174 chp from it!
Stock crank, stock rods (well, with arp bolts), oettinger but cast old mahle pistons, dual port 1300 heads and single throttle body.

Thats 100 hp more then you say is possible.
I guess my car is called 'Mythbuster' for a reason

Well, I'am allowed to brag once in a while right?

Sweet!!

Most wouldn't even consider a 311B suitable for that kind of power without the ~$100 of ARP rod bolts...I don't think I'd stand next to that engine for many dyno pulls before I got to feeling like I'd better seek some cover.

Wally wrote:...Hey Marc,...stock rods (well, with arp bolts)...Thats 100 hp more then you say is possible.
I guess my car is called 'Mythbuster' for a reason ...

Let's not be putting words in my mouth, I never said it wasn't "possible" to get more than 70HP out of an engine using stock 1200 rods...I said it would be "folly" to do so - I'm talking about an engine that'll last a while, not some dyno queen. Hell, with boost + nitrous you could probably pull 300+ HP from a 1500 using 40HP rods - for long enough to print out the numbers, anyway

What sort of revs were you doing with that 40hp?