corolla_nut Posted January 25, 2009 Report Posted January 25, 2009 I've searched eBay and the entire RC forum and checked google results, but can't really find the answer or info I'm after. We're chasing a little more power in my 4K ke55 corolla (bored out 40 thou, 40 thou oversized pistons, underspec 3K head, electronic dizzy, reground cam, completely rebuilt and balanced, extractors, twin 1 1/2" SU's, etc) and we are investigating installing a Racing vacuum pump to take care of the brake booster and catch can. Has anyone done this before? Has it made a significant difference? Any estimate on cost, parts, time etc. Any help would be great :hmm: Cheers Kylie Quote
Redwarf Posted January 25, 2009 Report Posted January 25, 2009 I wouldn't bother. I know of nobody that uses one, or has even contemplated one. Save you money and build a CAI or the like. Quote
Rollasrus Posted January 25, 2009 Report Posted January 25, 2009 Just a suggestion, if you need more vacum for the brake booster could you not install an alternator off a diesel that has a vac pump built into the back of it then plug you vac lines from that to the brake booster. Quote
corolla_nut Posted January 25, 2009 Author Report Posted January 25, 2009 It's just a thought at this stage. It was suggested to me by a guy heavily into drag racing, which seems to be the intended application of the vacuum pumps. The main reason why the thought was there is that there is enough air coming in via the pcv that it causes my idle speed to go up to 1800 revs, and I can't close the butterflies any more on the carburettors. Running about 12-14 degrees initial vacuum advance, which is what the distributor guys said to run (its been regraphed to suit the cam/compression). I blocked the pcv pipe down at kandos which improved the idle dramatically, still can vary a little bit though. I'm going to investigate whether the brake booster is leaking or not tomorrow, If it is, its not leaking heaps, but it is possible. I don't know why I have this problem with the pcv. The crankcase may not be sealed correctly and it is sucking air, but I never had this problem with the old carburettor/manifold setup. Maybe the manifold is a smidge small to run the pcv off. I don't want to get rid of the pcv though, I need the oil as clean as possible as long as possible. A diesel alternator/vacuum pump is an idea, but I haven't found out which vehicle to obtain one from yet... Quote
SLO-030 Posted January 25, 2009 Report Posted January 25, 2009 Ive heard of running your sump under vacuum can improve performance. Pretty sure i read it in Street Machine, apparantly an old method of upping performance. Quote
philbey Posted January 25, 2009 Report Posted January 25, 2009 all the drag cars running vac pumps are for the crank cases. Evacuating the crank case means you can reduce the air drag on the pistons. Basically putting a negative pressure on the underside of the piston, as well as evacuating any blowby past the rings. I really wouldn't bother, you need quite a high output vac pump, plus you need one with the right seals. Your idle issue will more than likely be an issue with leaking or incorrectly set up carbs. Did you have them balanced correctly? Quote
KEI069 Posted January 25, 2009 Report Posted January 25, 2009 Your idle issue will more than likely be an issue with leaking or incorrectly set up carbs. Did you have them balanced correctly? I agree with with this, it sounds like you have an air leak somewhere. The vacuum pump is used mainly to supply vacuum to the booster in engines operating with low vacuum conditions such as wild cams, boosted situations. Dragcars are a different setup altogether. Quote
love ke70 Posted January 25, 2009 Report Posted January 25, 2009 patrols, and most other diesels run a vac pump driven by the alternator or some other member of the motor. i think there is no need to do it on a 4k though, if you do it, dyno runs before and after thanks :hmm: Quote
corolla_nut Posted January 26, 2009 Author Report Posted January 26, 2009 Your idle issue will more than likely be an issue with leaking or incorrectly set up carbs. Did you have them balanced correctly? We've had the su's balanced, we've had 4 different mechanics with extensive carby experience go over them and tell us that there's nothing wrong with them. We have sealed and resealed and resealed again the manifolds and carbys and every possible place that there could be a slightest chance of a vacuum leak. Needles and jets and needle and seats have been replaced, the whole thing has been rebuilt thoroughly, butterfly's have been replaced by carby services australia. To clarify how much play there is in the throttle shafts: there is half a mickey hair worth of play and we have been told by several experienced people that this should not be causing any problems at all. We think that there is air getting into the crank case and making it's way into the PCV. We'd just like to make the car idle consistently because it is bugging the shit out of me. I'm not too sure about the racing vacuum pump, it's only an idea that we're researching. We were also thinking that air may be getting in through either the tappet cover, sump or dipstick? Thanks for your replies guys! Quote
philbey Posted January 26, 2009 Report Posted January 26, 2009 sump would be apparent by the amount of oil you'd be seeing. A very small air leak would be enough for oil to get through. Tappet cover and dipstick are a cheap easy replacement job at least. Quote
corolla_nut Posted January 26, 2009 Author Report Posted January 26, 2009 Cool Well it definitely wouldn't be the sump then! I'll look into the tappet cover and the dipstick. Thanks! Quote
philbey Posted January 27, 2009 Report Posted January 27, 2009 Now that I think about it, I had a CA18 with a dodgy rocker gasket, and that leaked an absolute shitload of oil out of it too, so it's probably unlikely yours is dodgy if there's not much oil around there. Quote
love ke70 Posted January 27, 2009 Report Posted January 27, 2009 i say it has nothing to do with a vacuum leak in the crank case, seems highly unlikely. just block everything and start plugging shit back in. see what f@$ks it. then work out why. Quote
orangeLJ Posted January 27, 2009 Report Posted January 27, 2009 I run a set of triple inch and three quater SUs on my 202, and have had drama after drama with them from day one. I ended up rebuilding pretty much everything. New needles, new butterflies, new throttle shafts, new piston springs etc. I still have problems with one of the carbies, no matter what we do or how many times we balance them and drop or raise the flats, its never run as perfect as the other two, its always too lean or too rich (usually the latter) sometimes they can seem, perfect and still be rotten pains in the bum. If you are chasing a vacuum pump to mess with, VK commodores, non injected ran a vacuum pump, lots of them are now seized up or have been sent to the scrap heap but a wreckers with any old VK vacationers or some of the other models with the black 202s (non injected remember) should have vacuum pumps, they ran them as part of emissions gear. Quote
Budowski Posted January 27, 2009 Report Posted January 27, 2009 (edited) I like this discussion will be very interested in the out come. I found this a interesting read may not entirely suit a small capacity engine but the idea is still there. http://www.gzmotorsports.com/vacuum-pump-guide.html what setup from the factory do motor bikes run to sort there carb tunning isses and crankcase issues ? most hi powered bikes run an engine to the same or close capacity as an 3k/4k. the last product on this page might help http://www.et-performance.com/kv.html#METR..._&_CRUISERS and these guys are having a massive discussion about the same thing you guys are 1/2 read it very intersting http://www.gassavers.org/showthread.php?t=7233 Edited January 27, 2009 by Budowski Quote
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