Ian Summers Posted March 16, 2019 Share Posted March 16, 2019 Hi all, I'm currently in the planning/parts-buying stage of a 280z project that I intend to really dig into once the weather warms up enough to put in some real hours in the garage. It's going to be a mild restomod that's mostly for riding around and looking cool in (at least as cool as I can look, anyway), nothing too wild performance wise. Currently, I have an l28 out of a 79 280zx that I'm freshening up a bit. It's going to be honed and rerung with new rod and crank bearings, gaskets etc. I plan to run a disco potato clone from CXRacing (https://www.cxracing.com/TRB-GT2871-64-RRB?search=billet dual ball bearing gt28). I'm also cleaning up the ports and cutting out the exhaust port liners for a few reasons. Firstly, I won't be running an intercooler, for reasons having to do with throttle response and cost savings - I think it should be fine for my relatively low power goals (going to run 10psi and hopefully make 225whp). Secondly, the turbo is possibly going to have a smaller than stock turbine housing, using an internal wastegate (i.e. higher EGT's... ergo potentially melted liners). My question is this: given the displacement of the engine, the relatively low boost I plan to run, and the smaller than stock size of the turbine housing - If I use the internal wastegate, how likely am I to run into boost creep issues during prolonged, higher rpm operation (think fifth gear pull to redline or something). I'd prefer to run the internal, for simplicity and ease's sake, but if there's a potential flow issue there, I need to make the commitment to running an external now. Any and all feedback you guys have to offer (even apart and aside from my question) is also welcomed, of course. Quote Link to comment Share on other sites More sharing options...
Gollum Posted March 16, 2019 Share Posted March 16, 2019 At those power and boost levels creep shouldn't be an issue. The .64 AR is likely fine until you're pushing near the 300whp level. Quote Link to comment Share on other sites More sharing options...
guyz Posted March 16, 2019 Share Posted March 16, 2019 Funny, after so much deliberation I've just today decided to use that exact turbo to replace my ruined t3/4oe Will be ordering it on Monday when I can benefit from a 10% of sale. Sounds like it will net some significant improvements. I've already ordered the t2-t3 adapter and a 5 bolt, 3" V band. Will build a new 3" downpipe, replacing my decent 2.5" homebuilt and ceramic coated one. I'm excited to see how it works out, being a much more modern and advanced turbo. Wish you could offer some actual use feedback but I guess I'll beat you to the guinea pig role! Will be happy to relay my experience/findings. Quote Link to comment Share on other sites More sharing options...
Ian Summers Posted March 16, 2019 Author Share Posted March 16, 2019 28 minutes ago, guyz said: Funny, after so much deliberation I've just today decided to use that exact turbo to replace my ruined t3/4oe Will be ordering it on Monday when I can benefit from a 10% of sale. Sounds like it will net some significant improvements. I've already ordered the t2-t3 adapter and a 5 bolt, 3" V band. Will build a new 3" downpipe, replacing my decent 2.5" homebuilt and ceramic coated one. I'm excited to see how it works out, being a much more modern and advanced turbo. Wish you could offer some actual use feedback but I guess I'll beat you to the guinea pig role! Will be happy to relay my experience/findings. If you could let me know how everything works out for you, that would be awesome. Thanks man! 4 hours ago, Gollum said: At those power and boost levels creep shouldn't be an issue. The .64 AR is likely fine until you're pushing near the 300whp level. My thought was that the boost creep would be an issue specifically because of the low power level I'm at. I.e. I'm going to be trying to send so much exhaust through an internal wastegate in order to keep boost at 10psi, that at like 5500rpm, the internal gate just won't be able to flow enough - where as if i was operating at a higher boost, I may be able to just send more through the turbine. Am I thinking about this issue correctly or am I way off the mark? Thanks for the feedback. I'm not experienced running a turbo this small on an engine this large, so I'm hoping someone here's done it and can speak to it. Quote Link to comment Share on other sites More sharing options...
Gollum Posted March 16, 2019 Share Posted March 16, 2019 Boost can creep in low and high boost situations depending on the airflow profile of the engine and size of wastegate. Using matchbot (Google it) I think you're going to last at about 50% wastegate actuation from 4-7krpm. This is assuming the wastegate port is about 1" or 25mm and using the turbine flow map found here: http://turbochargerspecs.blogspot.com/2013/02/garrett-gt28rs-gt2860rs-62-trim-360-hp.html?m=1 Learn to use matchbot. It's extremely useful. Quote Link to comment Share on other sites More sharing options...
Ian Summers Posted March 16, 2019 Author Share Posted March 16, 2019 1 hour ago, Gollum said: Boost can creep in low and high boost situations depending on the airflow profile of the engine and size of wastegate. Using matchbot (Google it) I think you're going to last at about 50% wastegate actuation from 4-7krpm. This is assuming the wastegate port is about 1" or 25mm and using the turbine flow map found here: http://turbochargerspecs.blogspot.com/2013/02/garrett-gt28rs-gt2860rs-62-trim-360-hp.html?m=1 Learn to use matchbot. It's extremely useful. I did some searching before posting, so I came across the Borg Warner calculator. I don't have solid VE data for the l28, and there's other holes in my knowledge on the topic, so I don't trust my own conclusions from it 100% yet. Sounds like 50% actuation of the internal wastegate leaves me plenty of headroom before I have to worry about creep. Thanks for going out of your way to find that map and taking the time to have a look at that for me, it's appreciated. Quote Link to comment Share on other sites More sharing options...
Gollum Posted March 16, 2019 Share Posted March 16, 2019 Yeah I understand. For what it's worth I think a stock turbo motor is at about 94VE peak starting to trail off at 5300 or so and dropping down as low as 65-70 by redline. Improving top end flow with a better cam, valve unshrowding, and bowl clean up will help immensely. And thus hitting your projected 225whp at 10psi would be much easier. Though I don't think that's beyond reason with what you've mentioned. Quote Link to comment Share on other sites More sharing options...
Ian Summers Posted March 16, 2019 Author Share Posted March 16, 2019 6 minutes ago, Gollum said: Yeah I understand. For what it's worth I think a stock turbo motor is at about 94VE peak starting to trail off at 5300 or so and dropping down as low as 65-70 by redline. Improving top end flow with a better cam, valve unshrowding, and bowl clean up will help immensely. And thus hitting your projected 225whp at 10psi would be much easier. Though I don't think that's beyond reason with what you've mentioned. I'm actually more set on the 10 psi number than the 225whp number. I've heard things about the combustion chamber in these motors being prone to detonation and I want to run on pump gas, so I'm hoping to just set it to 10psi, put a conservative tune on it, and whatever it makes, it makes. I'm not looking to blow anyone's doors off, so I'm sure it'll be plenty fun for me. Quote Link to comment Share on other sites More sharing options...
Gollum Posted March 16, 2019 Share Posted March 16, 2019 You going to be running factory EFI? In and case it sounds like you've got realistic goals and such. Keep looking around here and you'll likely find answers to most your questions. Also never hesitate to reach out to our more active members. Quote Link to comment Share on other sites More sharing options...
Ian Summers Posted March 16, 2019 Author Share Posted March 16, 2019 (edited) 25 minutes ago, Gollum said: You going to be running factory EFI? In and case it sounds like you've got realistic goals and such. Keep looking around here and you'll likely find answers to most your questions. Also never hesitate to reach out to our more active members. No I have an old haltech e8. I got a distributor from an 82 turbo 280, and put in a 24+1 trigger wheel (so the ecu will see 12+1). I'm going to be running a wasted spark direct fire ignition set up using ls2 coils, and I have some top feed injectors from a neo rb25 (440cc/min), which will be run semi-sequential. I'm gonna set it up to run with a MAP, TPS, IAT and wideband O2 (all of which I have already). The rest of the fuel system hasn't been sorted out yet (read: I haven't thought about what I'm doing there, at all). But I think it should be easy enough to cobble together, given the power number I'm aiming for. Since I'm keeping the open R200 and just going up to some 205/60 tires, I'm contemplating using the haltech's boost by gear feature so i don't roast one tire in first or second gear. I'm keeping the stock speedo though, so I may need a gps sending unit or some other way to generate a speedo signal for the ecu. Still thinking about that, particularly the cost of doing that versus just getting an lsd (for budget reasons it would be one or the other). I'm likely 9 months away from having to make a commitment on that though, with all the body work and drivetrain rebuilding ahead of me. Edited March 16, 2019 by Ian Summers Quote Link to comment Share on other sites More sharing options...
Ian Summers Posted November 13, 2019 Author Share Posted November 13, 2019 On 3/16/2019 at 4:24 AM, guyz said: Funny, after so much deliberation I've just today decided to use that exact turbo to replace my ruined t3/4oe Will be ordering it on Monday when I can benefit from a 10% of sale. Sounds like it will net some significant improvements. I've already ordered the t2-t3 adapter and a 5 bolt, 3" V band. Will build a new 3" downpipe, replacing my decent 2.5" homebuilt and ceramic coated one. I'm excited to see how it works out, being a much more modern and advanced turbo. Wish you could offer some actual use feedback but I guess I'll beat you to the guinea pig role! Will be happy to relay my experience/findings. Were you ever able to get this setup together? How's she running for you? Thanks, Ian Quote Link to comment Share on other sites More sharing options...
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