KE55PIG Posted October 2, 2009 Report Share Posted October 2, 2009 Rough power estimate and some advice wanted. ported polished head, should i face it to raise compression a bit ? Cam Duration: 280/286 (in/ex) Timing in: 32/68 (seat to seat) Timing ex: 73/33 (seat to seat) lift at valve: .401/.401 (thou in/ex) Either standard 4k or 5k bottom end 32 Webber datra carby extractors what size exausht should i go with this setup Runs 4spd with heavy duty clutch looking for a pretty kw figure around 80kw plus at wheels Is there anything elso i should do ? Quote Link to comment Share on other sites More sharing options...
Taz_Rx Posted October 2, 2009 Report Share Posted October 2, 2009 1 7/8 pipe is what you want for the exhaust. Going any bigger will cause a drop in back-pressure and make it run worse. Cam spec will deffinately beneif from a rasied compression ratio. Double or stiffer valve springs would also help. 80rwkw is probably a little optimistic. Expect around 60rwkw and then you won't dissapointed if you get more. Thats for a 5k btw, 4k maybe expect 50-60rwkw. Quote Link to comment Share on other sites More sharing options...
philbey Posted October 2, 2009 Report Share Posted October 2, 2009 Mines got an agressive cam, more so than yours although I need to recheck that, and I managed 68rwkw. Also running twin 40mm sidedrafts, extractors, 40thou overbore. Quote Link to comment Share on other sites More sharing options...
philbey Posted October 2, 2009 Report Share Posted October 2, 2009 (edited) Oh and just to add I am running a stack of compression, somewhere about 11:1 static, so I'm probably stuck with big overlap cams for life.... Edited October 2, 2009 by philbey Quote Link to comment Share on other sites More sharing options...
Felix Posted October 2, 2009 Report Share Posted October 2, 2009 Go a 5k bottom end. You'd have SFA bottom end with a 4k running that cam. I'd be looking at around 10.5:1 CR. Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted October 2, 2009 Report Share Posted October 2, 2009 (edited) As I see it, 100bhp per litre is pretty well full race for these engines, so 1300cc will give 130bhp at the flywheel. That's 97KW and you lose 20% in transmission for you end up with 77KW at the rear wheels, in a car that won't be very daily-driver useful. So Mr Philbey's 68 would be right, and you could expect 50something from your setup even with compression at 10:1. Anyway, it will be a big improvement on stock!! Stock 45KW means 36 at the rear wheels!!! Edited October 2, 2009 by altezzaclub Quote Link to comment Share on other sites More sharing options...
KE55PIG Posted October 3, 2009 Author Report Share Posted October 3, 2009 yea cool ok so after the above thing what would be the next thing to do in search of power ? Bore the block out with a new set of rings ??.Also What su's be better then my carby ?? Quote Link to comment Share on other sites More sharing options...
Redwarf Posted October 3, 2009 Report Share Posted October 3, 2009 Anything is better than your carbie, with the exception of a standard one. Su's are better, Webers/ Dellortos even better. Also remember when searching for Hp, you're going to start finding the weakest link. Axles, diff, unis, gearbox. Not necessarily in that order. I'll be blunt. You're not going to pull 80kw ATW from an NA 4K. Or not without a substancial amount of cash, at which point you may as well put something else in. Taz is on the mark with 50-60. I'd say closer to 50. Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted October 3, 2009 Report Share Posted October 3, 2009 Inch & halfs I's say. Made for 1600cc MG-B etc. Maybe you could be the first person to try inch & 3/4s! I'm building inch & 1/4's, off Austin Healey Sprites, as I'm not looking for anything over 5500rpm. They are 85mm 'long' compared to the 105mm of the inch & 1/2, so I get more room for an airbox also. The Lynx manifold is the hard part to get hold of. Quote Link to comment Share on other sites More sharing options...
rob83ke70 Posted October 3, 2009 Report Share Posted October 3, 2009 go with a 5k bottom end, and run 11:1 static compression ratio. When you assemble everything make sure you have incredible attention to detail and cleanliness. I'd reccommend getting everything balanced. I'd definitely run an electronic dizzy regraphed to suit your cam and compression. I wouldn't go any lumpier than that, it will be all sorts of fun to tune and drive that! I'd pop either 1.5" su's or 1.75" su's on it, the 1.75's are easier to get your hands on (they normally put three of them on a 6 cyl) and I'd consult someone about what needles to run in it. I'd get your flywheel lightened too, as well as having everything balanced. And I reckon 2" exhaust would not be too big. I have a 2" on my 4k. Don't expect it to be very streetable, and expect to have to rev it to 8000rpm. Might be worth putting solid lifters in it should you go with a 5k. I'd fit a thermofan to it on a shroud, and maybe a gilmer drive on the alternator. I'd most definitely run a 4.3:1 diff and a 5 speed box, if you use a t50 then see if you can get a gearset that has less of an angle cut on the teeth or straight teeth (will be much noisier) because you lose less power in axial loads through the gearbox that way. Run maybe a 75w85 or similar in the gearbox/diff too. Lose any extra weight in your car as well. The fussier you are the better the results. Its all about getting every last little bit of HP out of it and then reducing every last kg. Even if you don't get as much kw at the wheels as you originally wanted at least you will have a fun little engine to drive. Robert. Quote Link to comment Share on other sites More sharing options...
rob83ke70 Posted October 3, 2009 Report Share Posted October 3, 2009 I've seen 1.75's on a 5k before. Robert. Quote Link to comment Share on other sites More sharing options...
Felix Posted October 3, 2009 Report Share Posted October 3, 2009 I've seen 1.75's on a 5k before. Yep I've got a set that I've run on my 5k. It went hard with the SU's, would arc up a set of A539's all the way through second. I ripped them off and ran a DCD weber as it is a much sweeter allround carb setup for performance/economy if you do a lot of km's and care about fuel consumption. Quote Link to comment Share on other sites More sharing options...
KE55PIG Posted October 4, 2009 Author Report Share Posted October 4, 2009 I'm So confused on what to do i wanna build the 4k but it could end up cheaper doing conversion maybe ill just flog it off i don't no what to do lol Quote Link to comment Share on other sites More sharing options...
rob83ke70 Posted October 4, 2009 Report Share Posted October 4, 2009 much much much more fun to work a 4k. they aren't that bad on fuel provided you don't go crazy. basically if you can drive it around on the street, it won't use THAT much fuel :) Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted October 4, 2009 Report Share Posted October 4, 2009 (edited) Build it!! Really! Build it! It doesn't matter how fast it ends up, the main thing is that you will learn HEAPS of vital stuff that will serve you well all your life! If it ends up being not what you want or you blow it up through a mistake, its only cost you a few hundred. You could, of course, start with 4grands worth of 4AGE or even more for my nice Gen 5 3SGE and then blow one of those up! 45years ago I bought a burnt-out Armstrong Siddeley Typhoon and rebuilt it- (no, its a car not a plane! same company made it) Took three years to get it on the road, but from there I went on to building rally cars and running my own business fixing cars in a workshop. 4K would be the best thing to modify in fun per buck terms, on par with Datsun 1200s. When you can blow rob83 away its time to take on Mr Philbey, and when you can beat him THEN its time to change engines! Edited October 4, 2009 by altezzaclub Quote Link to comment Share on other sites More sharing options...
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