Re: Here's some info for the GB & maybe an answer for chewy..... What a fantastic post good stuff. I am negotiating for a set of 2530's and if I don't get these then I am definitely in on the group buy. I only want these 2530's because they are a true bolt on fit. Rich
Re: how do the GT2530 compare to the GT28R ? To confuse the matter some places call a GT28R a GT25. When i was shopping around for GT28R's I was quoting Garrett part numbers and the shops where saying ah an a GT25. Turbo Chart Comparison I actually think these are GT28R's Garrett 320hp ball bearing turbos Yet in the comments says: "also says known as a GT25/30"? huh? Is that different to a GT2530?! It's obviously different from the GT2530 that ttzed have. Turbo Upgrade 4 - GT2530 roller bearing but the HP rating sure seem to vary. It's just all too confusing!
You have to ignore hp ratings & compare the specs...... the Turbo upgrade 4 on TTZ is just a rebuild of your stock turbos using Garrett roller bearing CHRA's in your housings that are machined to fit the new assembly. Hks Gt2530's use their own design mods of the Garrett turbo. Here are some specs I found to compare the turbos in question. They are listed as : T25/T28/GT28RS/GT2530. Compressor Wheel trim : 60/60/62/63 Inducer diameter(mm) : 42/46.5/47.2/47.7 Exducer diameter(mm) : 54.4/60/60/60 CFM (max) : 405/448/535/477 Turbine Wheel trim : 62/62/76/76 Exducer diameter(mm) : 41.7/41.7/46.9/47 Inducer diameter(mm) : 53/53/53.9/54
Ok lets have a look at the two turbos GT28R and the RS As it seems there is a lot of confusion about why I picked these ones. You will have to excuse me if I make any mistakes as I am a bit of a novice about some of this but I think I am right and will easily stand to be corrected by those that know more. Here is the GT28R turbo graph. If you look at it see how it reaches its maximum efficiency at between 5000 and 6000 revs. You can draw the conclusion that you can see it comes on boost at about 3500 revs and builds untill by 8000 revs its runs out of puff. Those lines I have drawn on there represent the amount of exhaust gas generated by the engine at those revs. So you can see that the more exhaust gas generated by the engine spins the Turbo up faster and so it moves the lines to the right across the graph. The SR20DET generates as was pointed out. 33% more exhaust gas as those revs. So the turbo spools up faster. So for the SR20 the lines move toward the right and the peak effeciency part of the curve moves to a lower rev range. Therefore the SR20 would spin this turbo faster earlier and come on boost earlier just cause it has more exhaust gas. Your peak efficency would be at probably 4000 revs but it would run out of boost a bit earlier at say 7000 which isnt a bad thing. Does that make sense? Keep in mind without a worked engine. The upper Rev limit is probably 7500 revs and the upper boost is about 20PSI. Beyond that we cant really use any extra turbo capabilities. To use high boost levels beyond 20 PSI you need forged pistons rods etc, essentially a racing engine. Now look at the AR 0.6 Disco Potato GT28RS The amount of exhaust gas we are generating hasnt changed. See how the 2000 and 3000 rev lines are in the area thats called the surge point. Cause we are off boost that doesnt matter too much. But the point is that the turbos come on boost later. To get to the point where the turbo is getting to it maximum efficency, we are looking at a point a good 1000 revs higher than than the GT28R. The big big advantage of the GT28RS is above 23PSI (where we are not going to use it). The damn thing just keeps pumping like a bitch way up to and above 30 PSI. Thats why it is so good on Johns slot car. His engine is built like a tank to take high boost levels and deliver very high power outputs. You can see how at 2 bar (14.5 PSI) The Turbo to be efficient has to be reved to almost 7000 revs. We have run out of our rev range at this point. So that high output isnt really realized. I think Johns Slot car revs to 8500 or so. The upshot of this is that the RS is a great turbo for high boost levels at high revs. Typically to release its best You have to run 30PSI. OMG at 30 PSI it would be AWESOME, No wonder John gets over 400 RWKW. The GT28R comes on boost earlier and is most efficient at 5000 to 6500 revs right where we need it. (A bit lower would be nice but what can you do). This why the SR20 DET would be good for this turbo cause it exhausts more gas and so comes on boost even earlier. Its not much worse for us it just comes on boost a slight bit later cause we only have 1500cc to drive it with. So the bottom line is. GT28R for stock engines running 24 PSI or under boost, and the Potato for High stressed racing engines built for high boost levels. Does that answer the question why the GT28R is what I picked for this group buy? You could lift the exhaust gas figures I put on the Other page og the thread in general and stick them into any of those turbo graphs and look what they do. That will answer most of your questions about 2530's etc
Here are the exhaust gas volume figures I generated So you can plug them into any Compressor graph you like.
Jezza I had a look at your link, The description looks just like a GT28R OEM Silvia S15 SR20DET T28 Turbo [14411-91F00] $775.00 Application: S13/S14 SR20DET or Custom Fit OEM S15 Silvia T28 Turbo T25 Flange GT28 Compressor Good for up to 320HP Ball-Bearing Don't settle for a used and potentially worn out turbo... Get this new in box OEM turbo!! [COLOR=-1] Funny thing is it calls it a T28 and then says it is ball raced. Mmmm, I wonder if it is an earlier version of the GT, cause the T series have been superceeded by the GT now. You used to have to order the T series with Ball races cause the standard one was sleaved bearing. No sure.
There seems to be some confusion between Pressure ratios and Boost pressure One bar (14.7psi) of atmosphere exists in any motor before any boost is applied, if one bar (14.7psi) of boost is applied then the pressure ratio is 2 (meaning 2 atmospheres of pressure) but it is only one bar (14.7psi) of boost.
Does any one know the AR of the stock housings? And how they compare to the GT28R, GT28RS and GT2530?
Re: 2 Bar is 29psi Chewy, You are right. But remember what we are talking about is pressure ratio inlet to outlet. Not absolute pressure. So atmospheric pressure is 14.5 PSI. If we deduct that from 29 PSI we get 1 bar of boost or 14.5 PSI !!
Yo Graham bro put me on the list please i need some info - firstly if i get these what other parts do i need to fit them aft5er the engine is removed. Is their a group buy for the other parts needed? And so what do i need to do now lol signup some where? thanks dude
Deposit payment. Ok first, when does the deposit have to be in by the $800 up front. When will the final remaining payment be due. And on the ttzed page do we just order it and select payment later or something ? Im working out my pay atm so there is a damned good chance i will be in this i will keep ya posted. And one other thing how do you pay the initial deposit.
Re: Deposit payment. aK and Clay man, Its a lot of money so when I spoke to Simon the deal I negotiated with him, was that we all would put a deposit of $500 payable in the 16th of June against the order on TTzed. The balance is payable on delivery at around the 16th of July till the 30 of July ($1220) that gives us some time to save up a bit. So when you go to the TTzed page and place your order click on the check out box, mark the pay on pick up box and on the 16th Simon will send out an email and ask that the deposits be paid. Then he will order the turbos. I do think this is an engine out job as they are not 100% bolt on. I have to get the turbos and work out the brackets etc so I can get them laser cut. Also the air intake pipe has to be cut, rotated and rewelded. I think I will be able to do that for you on an exchange basis. So after we have the turbos it may be a month or so till I have the mod parts worked out and sorted. The mod parts (brackets, pipe etc I will have to make but the cost will be right) The last thing is that I beleive these turbos will give around 300rwKw at about 16 PSI or so. If you want to push them harder up to 20PSi for more you have to change the actuators which of course is more money. I am buying new HKS actuators. With the standard injectors the upper limit will be about 12 to 14 PSI max. And probably about 240-270 rwKW Hope that makes it a bit clearer. GJ
ok thanks but.... Firstly what are actuators? sorry and the only reason i will get these turbo's graham is on the basis that somebody can provide me the pipes and etc... So im buying on the thought that after the turbos are recieved you are going to make me the parts for cash and exchange or whatever...so god forbid getting the turbos then cant do nothing withthem or spending hundreds more for parts to install them.. sweet thanks :thumbsup::zlove:
Re: ok thanks but.... Just going to be honest here: - an engine removal will set you back atleast 700 each way. ($1400) - Dumps will probably be atleast ($400) for a set. So id say you would want to have about $2000 to buy the additional parts required and to get the turbos in the car and tuned. You might get lucky and find a mechanic that will have a go at putting them on the car without an engine pull. just don't want anyone to get a big surprise :/
Darkstorm is 100% correct I make no bones about it. This is a big job with a big payoff. From my point of view. I have to replace Stock injectors with 555 cc units, better actuators (these open the wastegate when you hit maximum boost) buy and fit a boost controller. Buy a set of dump pipes Then have the ECU tweaked up. The bottom line is I have alocated about $3000 (and its going to be tight) to get 350 RWkw at 20PSI. But a lot of work is being done by myself. You dont need to go that far and there are big benefits from running these at 12 to 14 PSI with boost jets and standard programming and Injectors. Its all about how far you want to push it. Most of the cars are over 12 years old anyway and the stock turbos are not gonna last forever. So at least with this you are removing a possible reliability issue for later on as well. And they are almost the same price as rebuilt change over turbos. aK, if you want to use them in basic boost 12PSI or close. You can use the standard actuators and injectors in the car and boost jets. The only extras are 5 bolt dump pipes, and a cut and weld on the intake pipes. (i will probably offer an exchange for a few dollars for this) and some boost jets fitted. Plus your engine in/out costs if you are not going to do it yourself
a pressure ratio should have no units if you are inferring that it's the ratio of the outlet to the inlet. So Grahams comment of is incorrect as it should say instead 2 bar is still 29.4psi Picky ay
Re: a pressure ratio should have no units if you are inferring that :LOL::LOL::LOL: yeah, but you can also see the graph starts at 1 BAR not Zero Bar !!!
Pictures Here is picture of one of the adapter plates that had to be made. Photo shot from underneath when on the hoist Picture of Dumps underneath
Thanks for the Pics Adam cool Shit they are close to the chassis rails arnt they!! Now I think everyone gets a real apopreiciation of hpw diffcult a job this is. God knows how you can do it engine in. I went and bought an engine stand today so I can do mine when its ready.
