RS500

Steve, EVOIV, fyi, the TD06SH L2 20G is actually rated at less power than the 56T GT3037S. although, i guess the difference in exhaust housing A/Rs is what is making the difference b/w power/response on these two engines. Steve, with an A/R .73 exhaust housing, you'll definitely pick up atleast 10-15rwkw on the same boost. good stuff btw, nice power/torque curve.

if you're planning on coming down to the northern side, i'd recommend seeing dennis at P.E.T Mods (9464-4225) as he's very very good when it comes to tuning RB's otherwise, Ben from Race Pace Motorsport.

JUN R33, firstly, i'd get my fuel system checked out while running it up (i.e., fuel pressure, fuel volume flow, injector duty cycle, etc) although, it could also be due to your intake charge being mixed with oily mist from the small amount of piston blow-by being produced by the engine and recirculated back into your intake. you can confirm this by checking to see whether your intake pipes (before the turbo) are oily. if this is the case, the air/fuel mixture being forced into each cylinder is not able to burn properly causing lean mixtures, therefore, i would recommend you get an oil/air separator fitted. good luck and let us know how you go.

Steve, i believe the .61 would be a little too small for an RB25DET. You'll ideally want to go with the A/R .73 for the street. This will give u a nice balance b/w response and top-end flow/hp.

which one is it?? please send pic to [email protected] thanks.

No probs SydneyKid. what do u mean by the comment above about standard and more standard parts?? would be able to tell me what wheel trims and housings the RS500's used to make the power they did back then?

well, he won't be getting that with a GT25, that's for sure.

good to hear and i hope you make the power you want.

so what were the problems that you resolved to make it feel better?

Evan, i think the .64 should work good for the street. my friend's turbo had a weak actuator spring which means it was opening the wastegate and by-passing exhaust gasses at low boost causing slow boost build-up. re: wastegate actuator, try and get teh highest you can get for the boost u want to run, and then bleed it off as you mentioned. sorry, i don't know much about the Wolf 3D.

Nivek, i did a direct debit to their CBA bank account and i had no problems with them.

rb20-calais, damn, i was trying to get in contact with him about the turbo. i'm not too sure how it will be with the .86, although what i was trying to say is that seeing as though the exhaust wheel is not very big it doesn't take much exhaust gas to get it spinning hard so it shouldn't be too laggy. Although, my friend has the -0032 GT25 turbo on his RB20 with a A/R .64 and boost comes in hard at about 4200rpm (with heaps of boost creep before 10psi) so it can be bettered. One thing to know though is that his turbo has a 56 trim GT35 wheel in an A/R .60 compressor housing which helps it hold efficiency at higher boost whereas you have a 48 trim T04S wheel in an A/R .70 comp housing which will introduce more lag than my friend's turbo, so yeah, maybe you're better off going for the .64 exhaust housing.

no probs Yogi. It always pays to do your research i say.

Steve, it's all good dude. my comments were based on my belief that the garrett gt turbo's are just as good as the hks, except for the lack of options in different comp. housing A/R's. This is where i believe most of the difference in response and compressor efficiency is seen b/w the garrett and hks turbos. actually, my same friend with the R32 GTS-T (as mentioned above) which made 227rwkw with a 400hp garrett GT25 (-0032 core) on 20-21psi, has actually purchased a genuine HKS gt2540 and he'll be doing back to back testing on the same dyno so it'll be interesting to see the results. I'll keep you all posted.

cheers dude.

check these guys out. http://www.greenline.jp/catalogue/bcpartli...=R33B&intake=FI i've dealt with them and they are quite good and reliable.

rb20-calais, i think you should be fine if u went with the A/R .86 exhaust housing as the exhaust wheel (actually, same as HKS GT2530/35/40) isn't very big so it won't be too laggy. This should allow you to get your 230rwkw goal at about 18-20psi, although max. power would be at higher rpm as compared to when you'd have the turbo with an A/R .64 housing. good luck and let us know how you go. btw, did u buy the core off menios?

Steve, just in the knick of time when i needed it, i have something for you. FYI, an R32 GTS-T (RB20DET) with a genuine HKS GT2535 was just tuned to 1.4bar (20psi) on the same dyno as mine was (so, no excuses about different dyno readings, etc) and it only made 191rwkw. I must admit, i was told that the power curve is nice and fat so it should feel good on the street but i still find it strange that you say an RB20DET made 230rwkw with the smaller HKS GT2530 at 1.2 bar. i think the dyno figures might have been tampered with in your example. Also, going by your 2nd comment above, i'm sure you know that the efficiency and power is not dependant on whether the turbo has a ball-bearing or plain-bearing centre, whereas it will depend on the compressor wheel/housing combination. It's not that HKS turbo's are efficient at 1.5 + bar boost b/c they are ball-bearing, it's b/c they have a well matched compressor/turbine wheel/housing combination. fyi, a correctly matched compressor side on a plain-bearing turbo will keep on making power over 1.5 bar and that's for sure so again, don't rule out the mighty plain-bearing turbo fyi, i'll be pushing my turbo tp 1.4 bar soon, so we'll see whether it makes more power or not.

Sydneykid, sorry for all the questions although i'd like to find out more on what you guys did back in the late 80's, early 90's to extract as much power as you did from the sierra's. how did u guys go for cams, anything ballistic or not needed when running that much boost? i am looking at doing cams as to improve the mid-range to top-end power/torque, is it worthwile only to get my exhaust cam re-ground or should i get both exhaust & inlet done at the same time?

were the standard rods used to allow 9000rpm? what spec T04's were they (wheel trims, housings, etc)? btw, which team did u work with back then? were u involved in the ATCC? thanks dude. your help is much appreciated.

Amen Sydneykid, did u manage to read my last question to you re: sierra's?

Sydneykid, point taken although i have a comparison which i usually go by b/w my engine ; a YBD 16v twin cam 2L sierra cosworth engine with the 60-1/T03 sierra wheel (A/R .84 split-pulse exhaust housing) turbo and my friend's 24v twin cam RB20DET with a 400hp Garrett GT25 (-0032 core) with a A/R .64 exhaust housing. now the drivability of both cars is almost the same (apart from my friend's car having the lower 4.11:1 diff ratio over the 3.64:1 my car has and different g/box ratios) where full boost comes in at about 4200rpm on both engines, but he has slightly more power throughout the rev range. anyway, my engine managed to make almost the same power as him (me - 221rwkw : 16-17psi vs friend - 227rwkw : 20-21psi) on less boost on the same dyno. So i'm sure if i was to go down to a A/R .63 exhaust housing on my turbo, it would perform just as good (if not better) as the GT25 my friend has throughout the rev-range. therefore, i am still of the opinion that a good combo in a plain-bearing turbo will perform almost the same as a Ball-bearing turbo and for the amount of $$$ u save, it's worth going for that option due to rebuilds don't cost very much and there are many interchangable parts. btw, my turbo is both oil & water cooled and it also has a full 360 degree competition thrust bearing. P.S. what turbo combinations were you guys using on the sierra's back 15 years ago and what kind of hp were u guys making at what boost levels?

well, i am of the opinion that the same kind of performance can be produced by the garrett gt series over the hks gt range, as when doing my own comparisons, i have seen many similarities in wheel trims/dimensions, etc although the difference in housing A/Rs was interesting as the biggest A/R u would see on a hks gtxx turbo is a .60 whereas almost all garrett gtxx turbos have an A/R .70. this is where the difference in response and efficiency comes into play. EVOIV is right, it's just that hks has a lot of their turbos on the quick cars in japan, it makes people think that they are better, and that's why people aren't using garrett's equivalents. Steve, i have not managed to find the hks equivalent in a plain-bearing turbo but i have seen the equivalents in the garrett gt range. i'd love to be able to do a direct comparison on my engine b/w for eg, the HKS GT3037S and the equivalent Garrett based core (i have found) with the same HKS housings as to see the real difference, but i don't have the access to these turbos and to buy them outright is a lot of $$$ which i am not prepared to outlay.

JimX, that's cool re: wheels. what exhaust housing are u running? by changing your actuator and the tension on the spring, you will feel a big difference on how the boost comes in as you are possibly getting a lot of boost creep now which would be making the boost come in that late. a friend had this kind of problem with his R32 GTS-T as he re-used the factory RB20 turbo actuator on his 400hp gt25, but when it was changed to a 1 bar garrett actuator, boost came in much earlier and held it better across the board. good luck and let me know how you go with it.

JimX, i was told this by a friend that had tried a few different T04E wheels on both a 13b rotary engine and a VL (RB30ET) as he didn't get the same results (power/drivability) he did as compared to the T04B wheels. yes, the cossie engine is only a 2L 4-cyl, and is definietely capable of making a heap more power with a bit more rpm (as max power was made at 7000rpm rev-limiter), boost and tuning, but given that you still have the extra 500cc and possibly the weak w/gate actuator, yes, you should be making more power than mine at any boost level. I would expect that. btw, what wheels do u have in your turbo? Steve, i'll just go in point form so we don't get confused. i) you have a fair point about the HKS 2530, but my point was that for less $$$ than what you'd buy a 2nd hand HKS 2530 for, you'd make the power you want with a 'brand new' plain-bearing turbo (such as mine for eg,) with less boost. I'm sure the HKS 2530 can make more power than what i did, but it would be at the stated '1.3+ bar' boost unless your engine has decent sized cams and a ported which means more $$$ on top of the expensive HKS2530. correct? ii) everyone on this thread and this forum is writing that most HKS/Garrett turbos need to be pushed higher than 1.4 bar boost as to be in their 'efficiency range' and to make to rated hp. Also, a couple of friends have bb turbo's on their cars and they needed to push them a little harder than the expected 1 bar as to make to 'quoted hp'. Yes, HKS/Garrett turbos theoretically rate their turbo's supported hp at 1 bar, but you tell me how many engines have actually made the 'turbo's rated hp' at the engine on 1 bar boost. iii) i could be wrong but i don't think the HKS 2530 can make 220-230rwkw on 1.2 bar with a standard engine. cams and a ported head would definitely be required. I guess this is where we are going, for the bb turbos to run in their optimum/efficiency range and produce close to the rated hp, they would depend on the volumetric efficiency of the engine to be high, hence the requirement of cams, ported heads, etc. iv) i could've gone for any turbo in the garrett/hks gt range, actually i was very keen on ditching my current turbo and going for a garrett GT30 combo b/c of the same comments/reasons which are mentioned in this thread, but i chose to stay with what i have as i got the same power delivery (if not better) than what i would've with a gt turbo which would've cost me atleast $700-800 more. i guess i can now spend the $$$ i saved on buying the plain-bearing turbo on regrinding my cams and making more power again anyway, i don't to start a shit fight, but what i was trying to say was that you could get the same power/drivability from the older plain-bearing turbos w/out spending the $$$ on a bb turbo.