Very early thoughts on exhaust were to use these headers and go to a pair of free flow or hotdog type compact mufflers to make a twin exhaust setup. Or is it better to go for extractors?
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Gavan,
Use the twin out manifold, those front pipes, mount the system like that one does... but those mufflers with the twin outs are generally completely crap from a performance perspective... you really want something that flows better.
any and all of the off the shelf extractors available will be hard pressed to flow as well as the stock twin out manifold, or provide similar gains for the $$... in fact the exhaust is something you should be doing straight away, with this old motor, right now! The Australian spec system is the restrictive USA spec one, except we didn't have the cat convertor... flow wise ...it really couldn't get much worse!
Then you can enjoy yourself while you do the hard yards with this rebuild...and enjoy it more when you transfer it to your 1300 / 1500 with whatever spec you settle on.
Similar with the carb / manifold upgrade we've been discussing be it a 34DAT or a 36DCNVA, you could use it now and enjoy, and transfer it to the fresh engine and enjoy it some more... plus you get some familiarisation time with the carb so your fresh engine will be somewhere close to begin with tune wise.
SteveC
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Another engine I've been peripherally involved with in recent years was RossH 's 1600 stroker. I suppose I was a "surrogate" project manager for his build, I supplied a few of the bits and initially steered him in the 1600 direction... and I get the feeling he is pretty happy with the results he managed ...here's a little excerpt from our conversation way back at the beginning of Jan 2011.
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I guess the engine rebuild is where the majority of the questions come in, and the specifics will depend a bit on how things look when we open up. I`m aiming for a warmed up 1500, that will be good fun as a fast road car and maybe a track day or two (the latter sounds like fun, but I have no prior experience of that!). Also want to get this right the first time around!!!
The general game plan so far for the engine:
1. Re-bore block, fit new pistons, rings, bearings etc (for cost reasons I`m going to be sticking with oversized stock pistons if possible)
2. Polish Crank
3. Light skim/dress of block top
4. Aim for CR approx 10:1 (not more than 10.5:1)
5. Lighten flywheel
6. Fit new Thermostat (supplied with gaskets)
7. Fit new distributor/oil pump drive gear (supplied)
8. Fit new oil pressure sender unit
9. Fit new oil pump
10. Fit new water pump
11. Fit Vics sump baffle
12. Remove mechanical fuel pump (not needed) and blank off.
13. Fit new (up rated?) clutch
14. Entire bottom end rotating assembly to be sent for balancing
15. Install New Engine Mounts at re-fit
16. Install CSC Exhaust header and free flow muffler (sending header for ceramic coating prior to fitment….pricey but hopefully worth it!)
17. Cyclinder head and inlet manifold are being sent for porting and flowing, and valves are being upgraded to 40mm inlet and 35mm exhaust.
18. Cutting existing cam to something along the lines of a 35/75/75/35 profile, with 10.5mm lift
19. Fitting ISKY valve springs
20. Am getting the existing 34 Weber modified per the PBS instructions, to keep overall costs in check for now. Sounds like dual 40 DCNF may be the ultimate setup but thats beyond my budget for now!
21. Fitting variable cam pulley from Vics
22. Fitting Crane Cams XR3000 electronic Ignition kit
I`m hoping that all of the above will yield a reasonable increase in power, and possibly allow the rev limit to safely be upped a bit (7500RPM ???).
Any ideas on what the above might yield in terms of power, and any suggestions on additional things I should be doing while everything is in bits?
One thing I have been pondering is how much power can the stock clutch handle, and whether I need to look at upgrades in that department? If I need to upgrade the clutch, what do I do, as I havn`t seen any upgraded kits available on Vics, and Midwest Bayliss etc ?
Cheers,
Ross
Hi Ross,
welcome to the forum.
The first thing in your engine rebuild...pistons.
Stock static CR for the euro 1500 is 9.2:1. The pistons have a large flycut for the valves cast into them. You state that you would like to up the static CR to 10 or 10.5:1... but you also want to use "stock" pistons. This can be done, but not by using pistons that are "stock" for an X19 1500. Several options are available, but basically they involve sourcing "stock" pistons from other models of sohc which have small valve flycuts and a taller compression height, which brings the piston top right up to the block face when at TDC. If you use the right pistons then 10 / 10.5:1 is easily done.
Cylinder head. There is not much point going for larger exhaust valves. The stock 33mm exhaust valve and port flows plenty of air, infact it just about outflows the stock intake valve. With minor mods to the seat throat and some attention to detail in the valve bowl, the stock exhaust valve size is certainly sufficient for the level of build your considering. Inlet valve size, there are stock Fiat valves available at 39.5mm, 37.5mm and 36mm. With near stock port size (28.5mm) and a 37.5mm valve head, plenty of additional flow can be achieved, and port speed is kept high (see "performance increase 1300" thread)
The trouble with large ports and valves is it usually leads to a loss of port velocity, this will make the engine very sluggish at low / mid revs until the port speed climbs high enough to fill the cylinder...it will feel like a two stroke motorbike with a narrow power band...just remember that bigger is not always better. A smaller port with higher air speed will make more torque across the rev range.
The second problem with large valves is the increase in valve shrouding that comes with the increase in head size. Again check the "performance increase 1300" thread for a complete explanation.
Induction. it's a relatively simple job to modify the stock manifold to fit a single DCNF carb. I had several made and sold them with new 36DCNVA carbs, and the results were excellent. (look in the FS&W section and check out the pictures) Modifying the 34dmtr to have larger choke sizes (28mm on both) is more for dedicated track use, and is a compromise for street use. Remember that PBS only did this mod as it followed the rules for certain race classes in the USA, not because it was suitable or best for the street.
In South Africa you get Uno's and Tipo's don't you?
Consider stroking your existing engine to 1600cc by using a crank from a 1372uno engine (67.4mm stroke)
SteveC
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I'll try to dig up more of Ross' build decision process, and if your reading this Ross, feel free to add anything relevant into this thread.
I think we all can see there are some very common themes in
all of these builds.
Firstly, they have come up with a plan, settled on a goal, and (generally) come up with a budget and stuck to it.
Paul would be the exception to the rule in all these examples... but I don't hold that against him... his goal hasn't actually changed as he's still aiming for the same sort of HP and torque... but is going to get there a little differently than the way he first thought of!! He is still in his decision making process, he's been fortunate enough to have had other parts offered to him, he is still moving forward and above all else, he still has his X on the road.
He has gone from doing a few small mods to a cylinder head (which is completed and it's ready to swap over if he ever needs to do it) to now succumbing to the appeal of the extra capacity and tuning potential of a 1500, even thinking 1600!!
Next common thread in all examples is a piston change and following good engineering practices to bump the static CR to a more "performance" oriented level.
And the third common theme is sticking closely to some of Mr Lampredi's original design parameters.
1. Bumping the CR but only to the 10 /10.5 :1 region. For a mild performance build any more is going to be wasted in pumping losses.
2. Euro 1500 cam is a favorite and a good choice for this type of build. Long duration creates issues, high lift is a waste of time unless you know the head is capable of flowing at those lifts. Regrinds have all sorts of issues with cam timing and valve lash...
3. Bigger intake valves are the business.
4. The stock twin out exhaust manifold and a well made exhaust will make HP and is worth every penny
5. You don't need twin carbs, a turbo or an engine swap to make your X19 fun to drive. Shoot for 90 to 100 at the back wheels on a sane budget, and really enjoy the fine piece of Italian engineering you own for what it is.
SteveC
