SM Hunter Posted October 21, 2014 Report Share Posted October 21, 2014 Hey, i have a 1975 Corolla Rally lookalike, i would like some more grunt from the engine, been lookin into carb, cam etc but thats expencive... soo i mmeasured the compression, it sits at 145 ish psi at its highest.. got some numbers form a guy on JNC and it turns out the orginal comression has been either 149, 156 or 171 psi orginal, and i also saw that the 3k-b had 185psi... does the 3kb have the same bottom end etc as a normal 3k? would my motor survive if i shaved off the head to get 180 ish psi of comression? how much would i need to shave of and would it run any strogner? -Tore Quote Link to comment Share on other sites More sharing options...
Taz_Rx Posted October 21, 2014 Report Share Posted October 21, 2014 Cylinder compression and compression ratio are 2 different things. And you won't really get much more by upping the compression RATIO without that Cam/carb/extractors anyway. Quote Link to comment Share on other sites More sharing options...
SM Hunter Posted October 21, 2014 Author Report Share Posted October 21, 2014 ohh. okay, isn't upping the compression the same as upping the compression ratio? the ratio is a x to 1 number and the comression is in bar/psi , i don't really see the diffrence? Quote Link to comment Share on other sites More sharing options...
Banjo Posted October 21, 2014 Report Share Posted October 21, 2014 (edited) Hi Tore, There is a very rough multiplication factor between CR & compression, but it is influenced by many things. Have a read of these articles & you will see it is far more involved http://www.type2.com...ineg/comrat.htm http://www.healey6.c...on pressure.pdf http://www.csgnetwork.com/compcalc.html There is plenty more info about this subject if you care to Google it. Cheers Banjo Edited October 21, 2014 by Banjo Quote Link to comment Share on other sites More sharing options...
SM Hunter Posted October 21, 2014 Author Report Share Posted October 21, 2014 (edited) hmm okay, i tried reading but some of the words just got to advanced for me, but i think i understood a tad more.. but i don't really see why CR would matter here? apart from trying to calculate how many mm's i could shave of the head.. which i was hoping some of you guys could tell me :P the thing is, i don't really have enough money to buy a cam, carb, valve springs, extractors at this point.. buuut i got a friend who is at automotive mechanic school, he could shave the head for free for me... umm in one of this sites you linked to , they said i had to go full throttle , warm engine , plugs out when testing compression,... my engine was not warm and i did not touch the trottle... does that effect my results? Edited October 21, 2014 by SM Hunter Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted October 21, 2014 Report Share Posted October 21, 2014 and i did not touch the trottle...does that effect my results? Yes. You need the piston to suck in as much air as it can, under the usual running conditions of being warmed up. Have someone hold the throttle flat and crank it while you hold the compression guage. Crank it about 5 revolutions, you will see the pressure jump up in the first two and then go up slowly for the next few. That is only cranking pressure you are reading, the moment you start the car it will change, as the air is moving so much faster than at starter motor speed and it has a lot of inertia. On top of that, the cam makes a big difference as it determines the efficiency of getting air into the cylinder at each rev range. That is why motors with hot cams run badly at slow speed. You're asking the impossible, almost anyone who increases compression does it along with a ground cam, a free-flow exhaust and big carbs. If higher compressions were an easy answer then the manufacturers would release the cars with them. If you take 10 or 20thou off it will make a little difference, but you will need the other mods to make the motor breathe better. It will also lead to more piston ring wear and a greater chance of blowing head gaskets. The reason you have low compression is that the piston rings and the bore is worn, so the motor needs a rebore and new pistons to even get back to stock compression. Whip the gearbox off and have your mate take 2kg off the flywheel, that will make a more satisfying difference, & then save your money up until you can do the whole motor up. I assume finding a 5K motor in Scandinavia is pretty unlikely. Quote Link to comment Share on other sites More sharing options...
SM Hunter Posted October 21, 2014 Author Report Share Posted October 21, 2014 (edited) 4k and 5k is not an option,at this point there is about 10 corollas for sale in Norway ( mostly 3k's and some 4k) the cheapest at 860 aus, no car were ever sold in norway with a 5k or k50...can't find any engines for sale thats not like a 24hr drive to pick up... i used almost a year to track down a parts car to get a windscreen from :P bought it for 800 aus... did not have an engine... previusly owner took it out.. it was a 230hp turbo blowtrhough twin solex 2TG... anyways iv been thinking about a flywheel lightening aswell, but I'm not sure about balancing it after lightening :P then i'll listen to you guys i should save up for atleast a cam,carb and extractors before i shave the head, the only problem is that a cam regrind here is like 500$... so I'm trying to find a cam here on rollaclub instead.. :) extractors and carb will be a bit easier :) tell me if you see a hot cam for sale that you think i could afford ! Edited October 21, 2014 by SM Hunter Quote Link to comment Share on other sites More sharing options...
Taz_Rx Posted October 21, 2014 Report Share Posted October 21, 2014 Crow cams do grinds with whatever specs you want for about $120 if you send them a stock shaft....which should only cost you $20 odd. Maybe put up a wanted add for a stock Cam and request the seller to post it to crow. You could then deal directly with crow via email and Paypal and get them to post it to you. Quote Link to comment Share on other sites More sharing options...
Banjo Posted October 22, 2014 Report Share Posted October 22, 2014 (edited) Hi Tore, Altezzaclub is perfectly correct with what he suggests. Yes. You need the piston to suck in as much air as it can, under the usual running conditions of being warmed up. Have someone hold the throttle flat and crank it while you hold the compression guage. Crank it about 5 revolutions, you will see the pressure jump up in the first two and then go up slowly for the next few. You need all four (4) spark plugs out, so there is no resistance to the motor turning, from compression on the other three cylinders you are not measuring at the time. Take the car for a run for 20-30 minutes, until it reaches normal operating temperature, then take out all the spark plugs. Put a brick on the accelerator pedal to keep the throttle open, and ensure the choke is off/open. Get a mate to turn the ignition switch while you hold the compression guage. Make sure you measure all four cylinders. Take a note of the readings. It is important that all four readings are pretty close together. Compression figures well apart, I've found, usually indicate a need for a valve grind. All readings pretty low could mean that the rings/piston/bore are worn. To determine whether low compression is caused by rings/piston/bore wear, or valves, squirt a tablespoon of engine oil into each bore. Turn the engine over a couple of times, and then redo the compression test on the low reading cylinders. If the reading increases dramatically, then the low readings are probably as a result of rings/piston/bore wear. If the new reading stays pretty much the same, as before the oil was added, then the cause of low compression is probably valves. Hope that assists ! Cheers Banjo Edited October 22, 2014 by Banjo Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted October 22, 2014 Report Share Posted October 22, 2014 Extractors over here are about $220 new, I'm sure someone in Rollaclub could organise both for you. What about carbs?? We can get manifolds for a single DCOE Weber to fit the K motor over here, you might need one of those mailed over too. If not, the minimum would be a Weber 27/32 or whatever was used on small Euro cars back then. Volvos had twin SUs didn't they, although they would maybe be too big. The Lynx SU manifolds aren't made new anymore, they come up for sale on here now and then. Feel like quad carbs off a motobike and making your own manifold?? Don't forget fuel in this equation. More compression needs higher octane fuel or it pre-ignites. Can you get 98octane over there? There is a formula (that I have forgotten) expressing how many octane numbers you go up for every half a compression ratio. Over 9.8:1 you're probably on 98, I use 95 for just under that. Quote Link to comment Share on other sites More sharing options...
peterd Posted October 22, 2014 Report Share Posted October 22, 2014 I was told by a wise old corolla expert that the easiest way to get more power from the 4k was to swap the stock air cleaner for an open sports style one (+2hp), use 95 octane fuel because the modern fuel is different, and advance the timing to about 12 or 15. Quote Link to comment Share on other sites More sharing options...
Clapped out Posted October 24, 2014 Report Share Posted October 24, 2014 ^^^^^^Personally I'd just leave the stock air intake on, with the money you spend on a sports air cleaner, just put it towards a weber. As for fuel and timing, it really won't hurt it, just put in fuel of choice and I'd say 12 deg would be safe on a stock 4k, cheers! Quote Link to comment Share on other sites More sharing options...
SM Hunter Posted October 24, 2014 Author Report Share Posted October 24, 2014 (edited) Thanks for soo much feedback! ill try to source some stuff first :) i Think iv gotten hold of quad Bike barbs! going to head out and buy a TA60 with a T engine with quad carbs... il get 3000 nok when wreking it so i think 5000 nok is a fear price, will to to get it for 4500 :) hoping he got the orignal manifold and carb aswell :) it is goign to get used on the field :) does TA60 struts fit a ke20 ? looks like this one got new ones! could anyone tell me what kind of t engine that is? 2tc? 3tc? i don't know? http://www.finn.no/f...earchQuery=ta60 Edited October 24, 2014 by SM Hunter Quote Link to comment Share on other sites More sharing options...
altezzaclub Posted October 24, 2014 Report Share Posted October 24, 2014 oooh! Motor & gearbox into your Rolla! I don't know what will fit, the struts probably need the TA60 LCAs and steering knuckles to bolt onto. The motor fitment might just be a case of changing engine mounts, but it depends on how good that motor is. You'd have to remake the plate of the inlet manifold to fit the K motor. Cut the plate off the 4 pipes and angle the pipes, then weld another plate on with the inlet holes in a different place to fit the K head. Quote Link to comment Share on other sites More sharing options...
SM Hunter Posted October 27, 2014 Author Report Share Posted October 27, 2014 Yeah, I'm thinking about stuffing the 2tc into my Rolla, maybe get a new cam and osme extractors for that, 2tc parts are easy to get here compraed with the 3k :) what do i need to do to get the engine into it? will the stock tailshaft from the ke20 fit? or could i use the one from the TA60? enginemounts is not too hard, gearbox crossmember, i think i got a 2t crossmember in my other corolla, and i got a hydraulic clutch setup in that aswell so i think ill be using that.. but all this depends if the tailshaft fits into the T50 gearbox...? if not ill ditch the whole idea... wonderfull sound when you got 4 bike carbs! on the way home, waiting for the ferry ran trough 30 liters of fuel yesterday :P in an area 100 by 150meter ish :P Quote Link to comment Share on other sites More sharing options...
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