StockyMcStock

right that's it, if you insist on thinking any more, i will have to stab you through the internet.

yep, if it's a conventional multilayer gasket.

http://www.skylinesaustralia.com/forums/in...p;hl=twincharge hope that helps. do a search for "twincharge" and you'll get even more hits. edit: WHENNY: those turbos would have been way, way too small. you would have had ripper response but the top end would have suffered as you describe. you would need a MUCH larger turbo (or turbos) than that to have your sizing correct.

well i'm f**ked if i can explain it any more simply than i already have, so i'll just leave it there i reckon.

nope i can't.

i'm not sure i fully understand what you're getting at, but here's another way of looking at it that might help. the bigger turbo can flow more air because it is physically larger in every way, simple really. if the resistance to airflow downstream of the turbo (the piping, intercooler, bends, plenum, and head) remains exactly the same for both turbos, they will flow exactly the same amount of air at the same boost pressure, and the engine will make the same power. but that's not what happens. when you put a bigger turbo on and change nothing else, your head immediately becomes more efficient and imposes less restriction to the turbo's compressor stage, because the turbine stage is flowing more freely. when your exhaust back pressure goes down, you can cram more inlet charge in more easily each time the cylinder fills, so once again there's less resistance to the compressor stage. the fact that your compressor stage is physically larger than it was before doesn't mean much, only that it's capacity for outright flow has gone up, and so has its flow delivery characteristics (the compressor map has changed). note that this new, larger compressor stage will probably require less shaft speed to feed the same amount of air as before to the engine (at less pressure), which again lowers your exhaust back pressure as the whole thing doesn't need to be driven as fast. again, power goes up. the end result is a more peaky and nasty engine though. so i guess what i'm trying to get at is, the power gains you get aren't so much as a result of the compressor stage being physically larger, but as an indirect result of the turbine stage being larger. i hope that clears it up for you.

you're a bit off with your thinking regarding the reasons the larger turbo makes more power. generally speaking, the reason a larger turbo makes more power, or the same power on less boost, is that the hotside is not as restrictive as it used to be, because it is simply larger. when you drop your exhaust back pressure, power goes up. pumping losses are reduced so you get more power. the effect is magnified at high RPM and airflow levels as well. of course, the trade-off is response and boost onset. cheers

Well look at that, Lysholm started making a smaller blower than the 1600. First i've seen of a 1200 but i haven't been looking into them for about a year now. To size you one properly, i would need to know how much power you are chasing. On the RB20, anywhere up to 200rwkw i'd use the little 1200, it should be fine (note that i have not seen flow charts for it, but extrapolating from the other larger maps this is what i see) and anywhere up to 280rwkw i'd use the 1600. above that i'd go for the 2300. the lysholm blower will give you crisp boost response right off idle and hold it all the way through the top end. it's the best choice unless you can afford an Opcon Autorotor (basically an upgraded lysholm, but you pay for it) sizing turbos and superchargers like this and giving any kind of meaningful comparison is very tricky, and largely useless anyway. a few helpful things to consider; - your supercharger setup has no exhaust back pressure, hence no pumping losses in driving the turbine. this means more power. conversely, it requires crank power to drive the blower, so for the 2300AX you'll be using 30KW to drive the blower at 8000RPM, producing 1 bar of boost and 16 cubic metres of air a minute. this is, um..... quite a bit. and the blower has a safe redline of 14,000rpm. you see where i'm going. -because you have no exhaust back pressure, you get very good (read: almost perfect) cylinder scavenging. hence, a cleaner, colder, denser charge each time it fires. this means more power again. but not only that, because your charge is cleaner, colder and denser, you can run more ignition timing before it pings. again, more power. -you're running further from the detonation threshold, so you aren't too worried about it pinging so long as it's tuned properly. operating within sane power levels, if it doesn't ping, it won't blow up. pretty simple really. - for all the above reasons, you don't need to have a static compression ratio as low as you normally would on an OEM turbocharged engine. 9:1 would be great, 10:1 would probably do just fine as well. you would have a very nice power delivery too. 8.5:1 will do just fine if you don't want to change it though. if i had to guess (which i dont' like doing) your setup might run something like this: RB20DET 1600 lysholm excellent intercooler management excellent exhaust system big cams? i would suggest it would probably take you 12-15psi to get to 200kw atw, although my knowledge of the RB20 is limited. i know when we did calcs on my RB30DE plus a lysholm 2300 we were looking at 14-16psi to make 300rwkw. either way the final power figure is irrelevant, what matters is how it feels to drive on the road. with instant boost response and a flat torque plateau that just never stops, it will be a very nice thing to drive. it will sound pretty mean too i reckon.

and i call bullshit on a lot of this quote too. my reasons: 1: lysholm blowers are NOT very comparable to roots blowers, for reasons which the author later goes on to describe HIMSELF. 2. the lysholm is more efficient everywhere than any roots blower i've ever seen charts for, because it has an element of internal compression, which the author later goes on to describe. 3. "That means that a bypass valve can not fully shut it off". While this is technically true, looking at the 2300AX flow chart gives me a total power loss of less than 5kw when the blower is at 5000rpm and pressure change is 3psi. the chart goes off the bottom scale here but it would be safe to say that at idle, with an open bypass gate, your 700hp supercharger would be pulling less than 1kw from the engine. 4. "This also means that the supercharger is heating things up all the time which can result in a heat soaked intercooler, totally defeating the lower discharge temps." OOPS, that's bullshit too. outlet temps go up only when the blower is actually making pressure changes. if you have a bypass gate, it is completely unloaded at low throttle and idle, and outlet temps are always below 40 degrees. regardless of this, your gate will be recirculating the air PRE-intercooler so that "hot" air will never even make it through the intercooler core until you start boosting. /end rant. buy a lysholm.

didn't have time to read the whole thread, but i'll put in my 2c here anyway. i designed and built my own SC-14 charged setup on my RB30 a few years ago. it went from 91rwkw to 131rwkw on the same dyno on consecutive power runs with the blower switched off then on, no management changes. this was using the standard n/a management, not tuned at all. the car went quite well but lacked top-end power as you would expect from such a poor old supercharger. it was making just 3psi at max power! now, i have been busy working on my twincharge project and have had neither the time or money to do another project. but i know a certain gentleman in melbourne who is (very slowly) piecing together the parts to do a rather different GTR engine package using a supercharger. the ultimate aim is, i believe, 500hp at the engine and a torque curve to die for. if i were to do it with an RB20 i would use a lysholm (whipple or opcon autorotor) 1600 blower, a good set of extractors and exhaust and some tunable management, along with all the necessary aids that you would usually need (intercooler, fuel system etc). having personally seen and dissected the 1600, 2300 and 3300AX Lysholm flow/rpm/outlet temp/delta pressure maps it would be just right for the RB20. flow maxes out at around 500hp worth of air, so if you wanted 400 at the engine it would do that nicely. the 2300 will go out to 750hp or so, the 3300 upwards of 1000hp. i would also be tempted (if the engine wasn't being pushed TOO hard) to run a high compression engine, in other words simply use the DE version of whichever RB you have. no exhaust back pressure means happy cylinder scavenging and nowhere near as much reason to drop the compression ratio as you would for a turbo engine. then there is the boost delivery of the lysholm blower to consider, you will have full boost from right off idle all the way to redline, with no taper at the top end. all in all i think it would make for a great engine, and would certainly sound the goods. i say go for it!

if it's 3/4 inch (19mm or so) a slight kink won't matter. 3/4 inch is pretty big cubesy: only if it's a ball bearing turbo!

for 500hp, go the GT35/40 with 0.86 rear. it will be very snappy. you'll need a decent exhaust manifold too (not the stock one i suggest!). personally i'd go the 1.06 rear.

sounds a lot like a rooted/unbled lifter to me. if you're keen you could whip the cams out and pull the 4 lifters involved, clean them and put them back in. or just run it and hope they bleed themselves. it won't damage anything really if you do it the easy way.

too easy mick, throw me a pm when you're ready. it's on a stand and i have a block and tackle here if you need to get it into a trailer or something. i'll have to pull of the inlet manifold sometime too.

stick welded all of it! worst idea ever. next time i'm buying a MIG. and no there are no air leaks in any of the piping, i cleaned up everything inside when i was finished. car runs very well on a standard R33 base map. pod filter is fine, i heat wrapped the manifold to prevent the problems you describe. there's no intake pipe because i'm about to put a supercharger where it would go. function > form

I have an RB30 for sale, it's a complete bottom end in very good nick (180,000km but i suspect it's been rebuilt at some stage) with the head still on. No inlet manifold or exhaust manifold so it's perfect for an RB30DET build. It is a series 2 block so it has the oil and water line provisions tapped in already. Blows no smoke, has no rattles. Excellent engine ready to run! Asking $150 Located Northside, Brisbane. Cheers

look ma, no AFM! plus you get better response the closer it is to the throttle body, otherwise the engine has to eat 15L of air before it begins reading the correct signal. trust me the response is MUCH crisper when it's close to the throttle body like mine is.

dude, put your AFM in the cooler pipe. fixed.

busky it sounds like your compressor stage is attempting to work outside of its flow efficiency island, usually when pressure is high but flow isn't, like when you close the throttle and get reversion. turning the boost down will work, as will anything that gets more power out of the engine like bigger cams, bigger exhaust side etc - this will get the flow up higher instead of lowering the pressure, which is just another way of correcting the discrepancy in the two. it's not a very good thing though i beleive, as when you go outside the compressor's limits like that your outlet charge from the turbine is much hotter than it normally would be, if it was working within its design limits. so your inlet temps at the plenum might be getting up there, which is not so good.

danielson: how did you find the GT4088, and what rear did it have on it? at the moment i have the same turbo with 1.34 rear on my RB30DET and it is surprisingly good, considering it's a drag turbo designed for rotaries. in 2nd gear you get full juice at about 4500rpm which i was astounded at.

ummmm.... is it a PPG gearset or something?

i'm looking for a gearbox but can only afford $1300. also would need to be in brisbane. pm me if both of these conditions are suitable. cheers,

sounds like you need to make yourself a new manifold, too many problems i can see. pick your turbo to the exact specs you want, then go ahead and make a manifold to suit it. you can place the thing yourself then. even if you just tack it all together and get a pro to weld the seams, you'll get out of it for less than $500 AUD pretty easily. i would back my homemade low-mount tubular manifold against one of the trust cast manifolds any day of the week.

you can get material added to them at a cam shop, then ground back to whatever specs you want. it's not without danger though (pieces coming off) and costs a fair whack.

the firing sequence of the RB sixes is 1 5 3 6 2 4 IIRC - you will notice that each of the three cylinders linked by a common collector are separated by the firing of a cylinder NOT linked to it. when your back pressure spikes due to an exhaust pulse, you don't want that pressure spike being "seen" by another cylinder just as the exhaust valve is open there too, it will hinder gas exit and increase the work of pumping. so you separate them as much as you can. ideally then, six independent pulse housings would be ideal for your turbo, but it's just not practical. even better would be six individual tiny turbos, but that would simply not work.