discopotato03

This is an area that should interest all performance car people especially the turbo brigade for obvious reasons . The topic should be split in two to cover longevity of underbonnet essentials and minimising charge air temperatures . The primary drama is usually radiated heat from exhaust manifolds/exhaust turbine housings and the dump + engine pipe/s . You only have to look at the standard set up to realise that the manufacturer went to a fair bit of trouble with heat shields to make it long term reliable . Often we change the mix of bits to suit our performance needs and the heat shields get the flick . This can cause major heat problems to everything under the lid and can cause fuel fires amongst other nasties . I'm interested to hear other peoples experiences with heat shields , thermal blankets particularly of the aluminised (sp?) type which some car makers ie Ford use . I have tried using the Thermotech wrap on cast manifolds and cast dump pipes without cracking them . I have also used their wrap on a steam pipe manifold which also stayed in one piece though I only had it for 6 months . I remember thinking that some form of shield around the turbine housing would have helped , the engine pipe was wrapped . Its difficult to know how well the turbine housing copes with the "tea cosy" , would probably depend on the material spec of the housing . If its an early diesel housing ie TO4 its probably a lower spec material only designed to cope with diesel exhaust gas temperatures . I have seen a few of these particularly the split pulse type cracking up on the inside from overheating . I reckon water cooling would be essential for the cartridge bearings survival and a bit of time should be spent to make sure it thermosyphons properly when the engines shut down . High mount turbos have the potential for problems because the heat exposures have moved from down low in the bay to up high and closer to components not designed to cope with turbo heat . Real race cars are not going to have the sort of things around that make the mobile lounge room comfortable and there are more freedoms to relocate the essentials . Anyhow I'm interested to hear what did and didn't work for others . Cheers A .

So as to not hijack this string I will start another on heat issues . Cheers A .

Hm , still need convincing I think . Before I start I want it fully understood that I don't want to be involved in any wars of any kind . I am willing to learn from anyone and at worst agree to differ over conflicting views . Both blowers and turbochargers have their place and if one suited my purpose better than the other I'd use it . They both have good and bad characteristics so choosing the least worst is the go . I have a better grounding with turbos but having said that have used roots blowers on large (645 Cu In per cyl V16) two stroke diesels . I could go into the whys and wherefores of later versions with basically a mechanically driven via a free wheel turbo that becomes exhaust driven at approx half revs . That version makes 3300 BHP compared to 2000 for the blower version and the last revision did 3500 from the same capacity . Two stroke diesels are a long way from a four stroke petrol engine so they like different characteristics with forced induction . With car engines the best way to make early torque from limited capacity (without chemical supercharging ie NOs) is a blower of some kind because it can develop higher than atmospheric manifold pressure at low crank speed . Low engine speed torque is good but its not free horsepower because the power you get is after the parasitic losses of driving the blower . Its debatable how much manifold pressure is usable at low revs before detonation sets in ie wide open throttle meaning near maximum dynamic compression plus boost pressure . The way I see it blowers will always have a pumping efficiency problem because of the high surface contact area around the screws/lobe rotors and the casing itself which will be anything but cool in an engine bay . Turbos will also suffer from this but their thermal mass would be less so less heat to conduct to the air particularly at high flow rates . Thats interesting what you say about screw blowers at 70% efficiency as I've not seen that before . Turbos use rotary compressors and these are also not perfect because they will have an island of peak efficiency . In a perfect world this flow rate and pressure would coincide with the engines torque peak to give the coolest charge temps at that point . I would say that the greatest advantage the turbocharger has is its ability to recover something from the waste heat that is ejected from the exhaust . This is also not a free ride though it is a valid attemp to recover waste heat that the fuel was burnt to develop . Turbochargers have developed to the stage where it is not as hard as some think to get higher inlet manifold pressure than exhaust manifold pressure . The turbine and compressor combine to form the rotating group and its no exageration to claim the innertial weight loss through higher spec steel and aluminium alloys with thinner section blades in smaller diametres spun at dizzy revs can approach 50% of the old dinosaurs of the late 60's early 70's . Annular contact ball bearings have made a huge difference to the transient response of the rotating group compared to the high oil shear high contact area of floating bushes and plate / collar thrust bearings . What this ultimately means is that less exhaust gass energy read less restrictive turbines and housings are needed to make adequate shaft power with which to drive the compressor . Constant development is going into the science of gas turbines to seek more of the above efficiencies in order to lessen the energy requirement to drive them . To make an exhaust driven compressor work all of the exhaust gas must pass through the turbine/s . For the exhaust gas to have any energy it has to be hot ie expanding so turbines and housings are going to be hot . A turbine housings job is to collect the gasses and accelerate them into the turbine inducer blades via its nossle . The more efficient the housing and turbine combination is the less restriction it will cause . Turbocharging manufacturers style does not suit most of us because the compromises the manufacturer built in are not what we would given a choise . Legislation prevents them using exhausts and state of tune that promotes (to different degrees) what we want . They have to make what is economic green and socially acceptable to Mr Mrs and Miss - bad press means bad sales and economic suicide . So in order to get the prefered pressure balance across the engine we need to size the turbo so that it can make the best use of the available exhaust energy . The turbine generally needs to be somewhere near the same diametre at the compressor and its trim and housings a/r optomised to power the compressor efficiently . The compressor (just like the turbine) has to be optomised in diametre trim style and speed range to compliment the turbine . The following example is going to nark some of you and I truly wish I could remember where I saw it so you could see the results for yourselves . The engine was a ... wait for it... SR20DET , the turbo was a HKS GT3037 in 52T wearing a .73 a/r turbine housing . The housing was extrude honed - smoothed - , the cams were from Jim Wolf Technology , the exhaust mnifold was a long leged stainless thing with I think a merged collector . External gate was I think a 40mm Tial . The Garrett production engineer who had a hand in it said that on the dyno it was in crossover up to ~ 52-5400 rpm . I can't remember what else was done to it though a highly developed Nissan ECU , injectors , pumps and IC for sure . I think it had the early high port head with lots of time put into it . Now for me I want 3.1 litres of RB 6 because the capacity and CR should make the torque I want without boost most of the time . If I get the turbo right its exhaust side should have very little restriction if any off boost so no issues here . The increased airflow from the compressor should be easily generated because I hope to use a reasonably small trim (for a GT40 compressor) so that the turbine gets an easy time and its transients should be snappy . If it breathes well it should inhale loads of air without high boost pressure so the turbo should not be working very hard so again low turbine inlet pressure . If I thought I could use a blower of some kind that could do all this and plumb into an R32 bay , be efficient over a wide range of airflow rates and pressures and be quiet (engine exhaust and blower) and be tunable to fix any problems I'd probably do it . Cheers A .

Supercharging/turbocharging . Supercharging is really just another term for forced induction . What everyone calls a "supercharger" is a mechanical engine driven air pump of which some are constant displacement pumps ie lobe or screw and others are rotary or like the compressor side of a turbocharger . The disadvantage of the mechanically driven pump is that its out put does not match the rising air demands of the engine . This is why the mechanical supercharger (MSC) is overdriven by step up gearing so that a sane sized compressor can develop a head of pressure over the engine . The typical Roots or lobe type SC is a very inefficient device because it absorbs considerable crankshaft Hp to drive and its compressing efficiency is quite low . Its low because the temperature rise between its inlet and outlet is quite high meaning charge density is low and therefore some weight of oxygen is lost . High charge temperatures are bad because it puts the compressed air fuel charge (on the compression stroke) that much closer to the detonation and or pre ignition point . The rotary or "half turbo" style SC's suffer from low boost at low revs and probably too much at higher revs which has to be wasted . To quantify 1) If you add a SC an engine will flow a lot more air . I would say that if you put positive pressure across the inlet tract it should be capable of flowing a greater volume of a compressible medium . With respect to internal combustion engines we really should look at inlet pressure as absolute pressure meaning ANYTHING above a total vacum is positive pressure . Na engines only have sea level air pressure to work with at best so you could say they are supercharged at 1 Bar or one atmosphere . So if you can raise this pressure to above 1 Bar the tract should flow more untill the restrictions limit and maximise the total flow . 2) SC bypass open at idle ? It doubtful its turning fast enough to generate any real extra airflow . 3) Bypass open = no energy loss . Not really , you will get drive losses through step up gearing or belt drive frictional losses plus the innertia of the lobes or screw gears . 4) What does hold back top end Hp is turbine backpressure ? This is only the case if the turbine side of the turbocharger is not properly sized in relation to the expected power output and necessary exhaust throughput . If this is done its the system designers fault not the turbos . 5) No one ever talks about how total exhaust pressure costs horsepower . Many of my turbo related posts mention turbine inlet pressure which is between the exhaust valve and turbine housing but any measurable pressure south of the housing affects it . I think it would be more accurate to say that the 100Kw may have been lost to pumping losses against an exhaust restriction , sure when the turbine inlet pressure goes up the exhaust gas temp rises with it but its not diffucult to get around . 6) If the total exhaust pressure were zero . Well if it was I'd say we would have no scavenging going on . Just on this point SC engines do have dramas with their exhaust systems because they have to pass the exhaust gasses the engine produces in a supercharged state so the manifold runners and tail pipe + mufflers need to be large enough to handle it . Its a bit sad at low engine speeds with large pipes trying to get the noise legal let alone much extraction going on . The turbine side of our turbo (provided its dump pipe is properly made) tends to act like a partial muffler to a degree . 7) Truth is 500Kw engine takes 100Kw to compress its air ? This could be true with a mechanical SC though doubtful with a properly designed competition turbo engine . It is possible with modified production four valve engines (porting/cams/manifolds/turbos) to have greater inlet manifold pressure than exhaust manifold pressure so volumetric efficiency would have to be good . 8) Further truth is that SC engines run high boost with very low exhaust back pressure . Fact - could run high boost/high charge temp/high crank power loss and low exhaust manifold pressure if everything starting at the exhaust valve was sized large enough not to pose any restriction . 9) The heat can get out ? Maybe , but its too late if the damage was done on the way in and in the early part of the cycle . 10)Top fuelers would not use pump fuels and alcohol burns with less heat output . Large diametre stacks should not form any restriction so heat buildup should not be an issue in under 10 seconds . 11)SC engines detonation free because heat can get out , see 9) . 12)Turbo engines horribly succeptible to detonation because of heat trapped by high total back pressure ? Yep if you set it up to do that sure . If you set it up properly with the appropriate turbine / housing / manifold / wastegate / dump / exhaust - no chance . Please do not try to tell me that the turbo F1 engines could not get the heat out and would have been better off with mechanical superchargers . To round off , I believe the last of Lancias Grp B super cars used a mechanical SC/turbo combination . I think they were run in parallel with a priority valve that could feed the inlet manifold from either . So the SC got the ball rolling and the turbo took over when the SC tapered off . I guess the priority valve stopped one from backfeeding through the other when not loaded up . The idea was to have the best of both worlds and a broad power range from limited engine capacity . There is a fellow at the American site High Altitude Imports who is running a turbo and SC on a Honda engine and the development story is very interesting if you like that sort of thing . Cheers A .

Hi all , correct me if I'm wrong but aren't the oil restrictors made of brass ? I seem to remember AJ removing one from an L series block by screwing a self taping screw into it and pulling it out with a slide hammer . I dont think the interference fit is real tight . Cheers A .

I was in that position with a Bluebird that had a much modified rad support panel (foreigh R32 rad and hooge IC) . The answer was to fit a plunger (or as suggested to me dog cock !) style catch from a Datsun 1600 . It works well but the fabrication to fit it to the bonnet is involved and may damage its paintwork . Cheers A .

RedDrifter I'm 99% certain the GT-RS uses the same 446179-0067 cartridge as the Garrett GT2871R 52T . The RB specific GT-RS has HKS's own T3 flanged .64 a/r turbine housing and matches the RB's exhaust manifold and dump pipe . The compressor cover is port shrouded to handle the surge that these turbos would have if pushed at low engine revs . These features are what you pay extra for over a Garrett GT2871R 52T if you could buy it . You can buy HKS's turbine housings to at least make the Garrett marketed item "bolt on" but your on your own with the comp cover . ATP turbo sell GT2871R's without turbine housings as an upgrade path for the GT28RS (GT2860RS) and others would too . Crunch the numbers . Cheers A .

Garrett should be selling their new T3 flanged integral wastegate GT30 turbine housings in 2 - 3 months , worth waiting for I reckon . Don't know exact time frame - maybe sooner if imported direct . HKS sell theirs as well for the GT3037 Pro S . Cheers A .

I think re reading the original post the ask was for approx 230Kw with lots of mid range because the present turbo doesn't shove in the back till 4500rpm and full boost (16) till 6000 . My personal opinion is than any of these hybrids (2871 ie GT28 turbine , GT35 compressor) like engines with fewer larger cylinders ie 2L 4 . RB20's are no Massi Furgeson at low revs and need torque to give them some sting on a road car . Driving such a car with production gearing is frustrating if life starts at 4500 revs . My experience is that turbos with more airflow capacity than is requited is an exercise in creating boost lag , if you then throw in the biased compressor to turbine load imbalance its not going to be super responsive no matter what housings it wears . I wish data loggers were available so that people could see how they drive road cars 90% of the time , then they could make mods that feel good 95% of the time and be happy with them 95% of the time . I feel the truth of the matter is that a wide fat torque line in the middle feels good because you don't have to wait through several thousand revs to find some squirt . People like Corky Bell (Maximum Boost) will tell you that turbocharging can usually enhance torque between a half and two thirds of your typical engines usable rev range . If you go seeking a full output Kw figure it gives no clues as to how the whole power range looks . I think torque is the aim and if you could get enough of it who cares what the red line does . How much time do you spend there and whats the next step when it won't rev any more ? yep the next higher gear and if there's not reasonable torque at that point the whole lot falls flat on it face - useless . Anyhow enough of that , either a GT2530 or a GT-SS should put it in the 330 od RWHP range and be responsive . The 2871's will be a little less responsive , the GT30's more so and so on . Your call , cheers A .

60mm compressors move a fair bit of air if you spin them fast enough , I don't call ~330 wheel horse power too shabby . S14/15 BB GT28's are limited by a Nissan specific GT28 compressor and garden variety (for a GT28) turbine /housing/dump and exhaust manifold . If you used the GTiR manifold and a GT28RS (GT2860RS) the difference is huge . Not all 60mm compressors are equal and uncorking the exhaust side lets the engine see a whole new world . Cheers A .

Roy I did see mention of an early stripper verson that was supposed to be ~ 1170Kg I'd imagine with no pwr steer or A/C and armstrong window winders . The std 60mm piston cast steel calipers are quite heavy so the change to R32/Z32 alloy four pots would be equal or less . As you would know the more performance minded R32/33/34 rotors are bloody heavy because of their size and thickness . If you did the front brake conversion properly ie disks bolt to back of hubs not over studs you could probably have a 1200Kg car in road trim . If the sound deadening was flicked and a lightweight seat fitted is better again , and an R32 GTR radiator (honestly about a third of the weight of R30 dinosaur) and it goes on . SK once spoke of aluminium flywheels and his RB31DET - works well and saves weight . FJ20ET's have a pretty large (for 2L 4 pot) 240mm flywheel so a bit to lose . The "right" wheels such as Rays (Volks) have the right offset and are very light for their size (16x7 , 16x8) , have to assume they have forged centres and rolled rim sections . The R200 and thicker half shafts put a bit of weight under the bum but its needed to be reliable . With a bit of stuffing around you can get an R32 GTST box in (change bell and bore lower bearing hole) , same length same yoke . Cheers A .

Really need some pics to make the problem obvious to all . That TO4E of yours , if its using a TO4 hot side the housings tend to move the centre line of the turbo away from the manifold and I imagine closer to the engine mount . If you look closely at HKS's GT30 style turbine housings the mounting flange extention is very short (if you equate housings to snails I mean the bit where he'd stick his head out if he was born in a foundry) and the turbine outlet smaller and more compact that TO4 housings . That manifold would have been intended for GT3037's , GT3040's and GT3240's though if the external gate mount was blank plated a 2530 or any T3 flanged turbo may fit . Cheers A .

From turbobygarrett/products/turbochargers/small frame the maps look like this though the turbine housing used here was Garretts T28 flanged .64 housing . It'd be nice to think that the T3 flanged HKS equivalent would be better inside . I'm not sure which comp cover HKS use on the SS but it may be the slotted or port shrouded type used on the 2530KAI if its the 6 cylinder model specific version . Note how HKS have changed their thinking with older turbos like the 2510 and 2540 and the result has been the GT-SS (more open bladed turbine and smaller trim compressor) and GT-RS (smaller 71 vs 76 mm compressor of a more modern design) . The gain is response and far better compressor to turbine load balance . HKS turbos can be expensive but they bolt on where Garretts often don't and cost lots to adapt . You have to do the sums to know the final figure . Cheers A .

I actually like the GT-SS if you want mid range punch , its basically a 2530 with a 60 trim compressor instead of a 63 . I don't think I've seen a 2530 with the comp cover off and don't remember its cartridge number so can't confirm if its a late design wheel . I'll have a look at the 60T comp map to get some idea of its airflow / power potential . I can see the 4 to 6 cyl 2000cc comparison creeping in again , don't forget the SR20's pots are ~ 1.5 x RB20's pots and the exhaust slug or putt to the turbine is significantly different - enough to allow the 4 cyl a .86 a/r turbine housing where the 6 seems to be quite laggy with it and probably needs the .64 a/r housing . My 2 cents spent cheers A .

If you did the right alterations to an oil cooler adapter it could work ie without the cooler though they are a good idea . Cheers A .

That would be an interesting read if it was translated , anyone have the english version . Cheers A .

Mafia long shot but there may be a compressor wheel that should help your turbo . Its from the plain bearing GT3776 shown on turbobygarrett/products/turbochargers in the large frame section . Its a GT37 BCI-18 family wheel like the real GT30R/GT3037 turbos use . It would make it very similar to a GT3037 52T though with your cropped turbine . You could ask Brett from GCG ifs its available here or o/s and what sort of machining mods are needed to make it fit your CHRA . The GT3776 turbo part no is 452159-1 CHRA no 436085-1 . The comp cover to use would be a Garrett TO4E .50 a/r . Cheers A .

NOS only really helps a turbo thats large in relation to an engines capacity . If the combinations problem is a tiny turbine and housing gas merely helps it destroy itself sooner/faster . Cheers A .

Need turbos ID tag no's to identify it properly , 500Hp rating doesn't tell us much . Cheers A .

Yep you want it to be laggy , GT3040 that'll do it ...

Yeah Cubes LOL I was sort of wondering if I should get someone to host the "GT35RS" if it was a practical proposition . Seriously though the car should come before the turbo otherwise the economics of the project get all out of hand . I'm pleased it was noted that the VLT's gearing works out ok and think its a combination of the box and final drive ratios that suit the RB30 and I spose the approximate weight of a VL or R32GTST . When I crunched the numbers the all up gearing of the VLT looks better than the 33 box and taller diff . Its most likely a case of Nissan wanting that short 1st ratio so an R32/RB20DET combination or R33/RB25DET could idle around in Japans bumper to bumper without being snatchy or needing to ride the clutch . I'm probably starting a war here but either of the above would not be the most torquey things given what they have to haul around at low revs in std tune . The RB30 with its longer stroke and rods I'd say makes better use of its capacity than the 20 or 25 so its capable of significantly more torque at lowish revs . The difference between 1st - 2nd is better (closer) in the VL so this makes a big difference in how a car launches from start . One of the most infuriating things I find with Nissan transmissions is the big 1-2 gap , kills baulk rings and makes motors bog down . The VL has the wider gap 2 - 3 where it is better off because winding up 2nd is more likely to get most where they want to be and anyhow the 2-3 change across the gates takes a little longer and gives the syncro hub a short spell before it takes up . Also 3 litres would be less fussed pulling the taller 3rd gear . I should really try and locate a VL box before they dry up though I suspect the Navara V6 version of this box may have the same ratios - may even have the Skyline style shift and clutch slave mounting point too . Anyhow the combination of appropriate gearing and engine torque characteristics makes or breaks these conversions , I dont need upper end turbo torque because mid range pull makes the arguably tall gearing work - well on the road anyway . Latest thinking for "GT35RS" is maybe reprofiling the 56 trim GT40 compressor for 54 or 52 trim . Doing it this way means its (maybe) possible to use the original wheel which you have and its guaranteed to bolt back on . If this mod gained a following it would be nice to keep costs minimal on an already expensive bit of gear . Not sure what to do about the comp cover as there are a few options . We could use a TO4E cover like Ford did with the XR6T in .50/.60/.70 a/r or machine/press/stake a new section of aluminium into the original .70 a/r TO4S cover and profile it to suit . Thinking about it this gives the opportunity to play with port shrouding like HKS tends to do at times and could bolt in like their version of the TO4Z . The .60 a/r TO4S cover like HKS used on their GT3040/GT3240 is available os but in the mid 400's . Av a good weekend cheers A . Cheers A .

The problem is that the higher your make the gas speed the closer the tube or duct is to its maximum flow . Engines don't care where the restriction is but the result is the same . Cheers A .

From their site the maps look like this , though the turbine map should vary with different compressors at this site it does not . So you have ~ 21.5 lbs of exhaust flow if it has the .86 a/r exhaust housing or ~ 18 lbs flow if it has the .64 a/r housing . The energy recovered by an efficient 54mm turbine has to try and muscle a 76mm TO4S dinosaur compressor wheel that has the capacity to pump 49 lbs of air in its .70 a/r TO4S cover . That cover by the way if used on a GT35R can pass 60+ lbs of airflow and approx 75 lbs on a TO4R/Z so way overkill for 49 lbs . If you look at the compressor maps for the GT2860RS and GT2871R 48 trim they show 35 and 38 lbs of flow from a 60 and a 71mm compressor in a .60 a/r TO4B cover . The point of all this is that more modern compressors are far smaller than the dinosaurs for adequate flow and the comp covers or housings are more compact as well . The GT28 turbine is a high speed device as are the GT series compressors , the fact that they work together at high rpms means they compliment each other . The TO4S compressor from the GT2540R or GT2876R as Garrett now calls it is way out of step technology wise with its GT28 turbine . It has reasonable airflow for its size and trim but pumps it volume because it is big rather than efficient - for its airflow . It doesn't need high revs to work but the GT28 turbine does so this is where they fight each other and the result is boost lag . The Garrett site said - best suited to unique applications , not recommended for general performance applications . I don't know where you go from here , your compressor wheel and cover are the problem so its a case of change them or change the turbo to get better response . Probably not what you wanted to hear , why those turbos are on the market at all beats me . Cheers A .

54mm GT28 turbine trying (hard) to turn 76mm TO4S 48T compressor . Garrett do not give this turbo a glowing review on their turbobygarrett site (under products) . I'll have a look and back in a tick ...

GunMetalR33 I suggest you wait until April - May as Garrett is releasing FINALLY a few T3 flanged GT30 and GT35 sized integral wastegate exhaust housings . I'm sure these will match your GT30 turbine better than anything else so they are worth the wait . There will be a .82 a/r and possibly a .63 a/r version to suit your turbo . I hope its a real GT30R you have , ID plate should say CHRA no 700177-0007 . Cheers A .