Boost Junky: 2nd Saga - M50-T Project

[dirtydoogle 383]

0.63 a/r isn't very large. But I would expect boost comes along quite nicely?

[|ncary 0]

All the GT35's have a large compressor size, good for up to 4litres (or a 2litre that revs to 11k) so it makes massive power on low boost because it pushes such a large volume or air through, but you sacrifice maybe 1 thousands revs of spool time. You can see from the boost graph that he is getting full boost at 3750 or so, which is great! Most people run a GT35 on a 3.2 litre M3 engine, and have AMAZING results. So congrats must be made here to Luke and the Tuner. Cause it's a bloody good job.

*(to compare other spool times, I was going to run a GT28, which is quite slightly smaller, on a 2.5l M20, and have full boost at 2000-2500 and max revs of 6500 depending on wastegate placement, with 10psi giving 190-200kw to the wheels. So to get results like Luke has, a lot of things are done correctly and smartly.

Edited August 13, 2009 by Incary

[dirtydoogle 383]

Good point. Just thank god we aren't talking holset hx20 size turbo here and were talking more than an rhb51 =D Seems like the .63 would be a nice compromise.

[|ncary 0]

Haha yeah only redneck americans run holsets off their pickup trucks. Garrett's GT series are the most amazing flowing turbos ever made.

[dirtydoogle 383]

Yeah the garret gt turbo line up seem to offer good value for money also, generally quite strong and looking at boost maps they seem very competitive, the only better way to go would be mega money and a variable vane bugger. Or more cubes.... I have a mate running a holset hx20 off the side of a toyota soarer, jzz30, it's a bit...laggy.... even more laf than the to4e he took off....the turbo set up I was building for one of my toys would have come on boost at around 8k

[|ncary 0]

8k! Hope it was a Kawasaki engine revving to 13

[Mike 1]

Haha yeah only redneck americans run holsets off their pickup trucks. Garrett's GT series are the most amazing flowing turbos ever made.

haha might want to be careful who you say that around...

[dirtydoogle 383]

A honda vt250 revving to 14. Sadly I sold the bike today, but still have the spare engine there. Was running 1.4inch pipe [weird honda headers!] into a toyota ct12a, pushing through a cut down nissan s14b intercooler. The carb work was going to be interesting, a balance between jet size/taper vs needle height vs slide speed argh

Haven't got any pics of the turbo set up. It's just the headers + turbo on the spare motor at work.

Edited August 13, 2009 by dirtydoogle

[|ncary 0]

That's crazy, would love to see pics.

haha might want to be careful who you say that around...

Just generalising sorry

[dirtydoogle 383]

Never had time to get that far with it after all the paint and basic crap was done. 3 years of honda is kind of enough, not including my bros650 before that.

[e30plz 1]

What is this, NZHondas? Lol

Crazy amounts of torque, Time for skid vidsss.

Edited August 13, 2009 by James~

[dirtydoogle 383]

What is this, NZHondas? Lol

Nice work Luke, Time for skid vids.

Bikes are ok...not shetec puss teggvics

Yes, video skids!

[SIR E30 68]

Good work luke! all that hard work is paying off. *e-hand shake* well done

[Boost Junky 1]

Farking Hell! That must be amazing. You'll have to fix any camber issues you have in the rear to get some rubber to the road!

Nice work Luke, and I hope with all my boost related hope that the engine stays together for years to come.

You still have stock cams yes? That torque curve sure does dive after 6, some turbo minded cams would be a great investment in the future. I don't think you have any flow issues with that GT35

Haha yea its pretty impressive Henry! Yea thats another expensive job to do on the list.. the camber correction in the rear. Cheers man and yea the engine should hold mint tuner said its pretty safe at that boost. Yea stock cams atm im not that clued up yet on all internal stuff like cams and all that much learning needed here.

so jelous! awesome!

Cheers HT

Cams probably wont help as it appears the exhaust housing is an 0.63 which might be choking it off up top (but helping with spooling). An M50 already has naturally aspirated cams which are going to hold on to higher RPM than any typical "turbo" cam, which often have high lift, medium duration but close (or is it wide - can never remember) lobe separation.

I'd just wind it back to 12psi and enjoy. I suspect 250rwkw is enough

Yea I might end up taking her back down in boost yet I will see what happens once I setup my ride heights properly and camber and got some rubber on the rear but i'd say it may not be practical for the track at the power shes making right now. Haha yea 250rwkw would be more than enough Cam, shot for the advice believe me I have considered it.

Nice, now for a vid!!!

Not sure what your budget is looking like these days but....

You better put these on your watch list!!! phat rubber

I wonder how conservative the ignition timing is under 4Krpm???

It shouldn't be that laggy with a 0.63 turbine housing and as CAMB mentioned may be choking the topend.

Not that 270kw is anything to sniff at.

Glenn, Vid hopefully up this weekend I should have organised a camera for the trip home this arvo but got caught up in excitement lol. Its gonna be hard with no rego or wof... Budget is getting better pay all my bills off tommorow so next few months I can pour money into sorting out the last needed finalizations. Definitely have a set of R888s in the to do list mate. Is that quite laggy my car going by the graph? But yes indeed 270kw is very satisfying cheers dude.

Got two weeks to get it wof'd and certed Luke, I will be coming up for said skids, my car will be done by then, keeeeeeeeeeeeeeeeen? Loving those numbers, tis like e30 porn

Lol I wish Nath! I may know where I can get a wof but that would require finding standard bmw 5 stud rims and would have to get to work on heat shielding which is a major problem atm in my engine bay, something will catch fire if I keep driving it. Haha you and me both dude those numbers make my heart melt haha!!

Edited August 13, 2009 by Boost Junky

[dirtydoogle 383]

That's bloody good power for standard cams! Get something with an extreme lobe center and idle poorly and run out of vacuum whilst sounding awesome! Do it!

[Boost Junky 1]

Yea torque is badass eh but i think you have to divide that max torque figure 1885nm by the gear ratio in 4th so its like 440nm of torque. That would be awesome a nice set of lumpy cams lol!

Cheers for the comments Jason and James!

[CamB 48]

mops has 1 bar at ~3,000rpm in third gear with an Hx35 on his 2.7 M20. It depends on a lot of factors not the least of which is the gear selection and how much load the engine is under.

Incary - how did you work it out from the turbine maps? I want to try do so with my own engine. I have a GT2560R (going on a 2 litre M10 with an NA cam) so can see the turbine map but have no idea how to interpret it (I understand the compressor maps).

I've seen a dyno of a Gt2860 on an M20 2.7 which peaks low - like < 5500rpm. I think it did get good boost by 2500rpm though. However, I think I recall it being a T3 0.63 one, which is at least as big as a T28 0.86 a/r. I think a 2.5 M20 needs at least a GT28 0.86 or a T3 0.63 - the T28 0.64 will be too small. It'd be like driving my wife's Skoda - a massive rush of power and torque, followed by a long declining tail of power. Hard to drive, to be honest - I'd rather more progressive boost buildup.

[greenday-rulz21 4]

Seriously cool Luke. Can't wait to see a video of it.

Sounds like a lot of work has gone into this, and looks asthough you've got results. Well done.

[Boost Junky 1]

Shot Nick, wont be too far away hopefully. Yea so much time an effort has been put into this car, and so much patience as well.. im not a patient guy at all but this prject has taught me some! Cheers mate

[Guest FrantiC]

Ahhhh I'm so jelous lol mine would peal 1st and 2nd too at full throttle. But my sh*t's weak compared to this

MLS + dyno tune definitley on the to-do list for me!

Is your e30 something like this??

/DROOL

Edited August 14, 2009 by FrantiC

[Boost Junky 1]

Ahhhh I'm so jelous lol mine would peal 1st and 2nd too at full throttle. But my sh*t's weak compared to this

MLS + dyno tune definitley on the to-do list for me!

Is your e30 something like this??

/DROOL

Haha yours will be mint when its going John! Good too see you have an MLS on its way!

Yup pretty much like that, thats in the wet though so would see mine would be similar to that in the wet haha.. his exhaust housing looks bigger from that vid.

[|ncary 0]

Incary - how did you work it out from the turbine maps? I want to try do so with my own engine. I have a GT2560R (going on a 2 litre M10 with an NA cam) so can see the turbine map but have no idea how to interpret it (I understand the compressor maps).

I've seen a dyno of a Gt2860 on an M20 2.7 which peaks low - like < 5500rpm. I think it did get good boost by 2500rpm though. However, I think I recall it being a T3 0.63 one, which is at least as big as a T28 0.86 a/r. I think a 2.5 M20 needs at least a GT28 0.86 or a T3 0.63 - the T28 0.64 will be too small. It'd be like driving my wife's Skoda - a massive rush of power and torque, followed by a long declining tail of power. Hard to drive, to be honest - I'd rather more progressive boost buildup.

I think a nice big well placed wastegate will see a GT2876 .64 turbine turbo do very well on a 2.5 M20. With the big wastegate (like 50mm) you lose a bit of control over the boost pressure apparantly.. But it would make an amazing mid range monster for the Summit rd

The turbine graph is where the turbine reaches max efficiency after correcting the flow. First you must find the flow in lbs/min through the engine, corrected for VE. (For a 2.5litre M20 its about 35lb/min at redline at 10psi or something) So then you take the peak efficiency percentage of that flow over a range of revs (from 2-7000 in 1k increments) and then you can see if the exhaust will top out the turbine. This is what I assume is correct from the hours of reading I've done. No practical experience here.

So for a graph like this:

(Can't link the image sadly, but the turbine map on this page

So at 10psi (1.7 pressure ratio for noobs) the most efficient the turbine can be is when the corrected flow is at about 16lb/min. Which is almost (well, it'll be a little choked, would work better with more boost) 62% (the number on the graph) of 35lb/min that my engine would flow. So it'd go well untill you start revving over 6, but as said a big floppy wastegate would help that.

I'm pretty sure this is right hahahahaha.

Edited August 14, 2009 by Incary

[CamB 48]

I'm not sure it is - I looked into this in the past and the turbine map is the pressure ratio across the turbine (nothing to do with the boost the compressor side is making - its the pressure in the exhaust manifold, ie turbine inlet pressure / backpressure) and needs to be modified for temperature too (temp of exhaust much hotter than temp of air going into the engine, which is your 35lb). TBH, I don't entirely get how to apply it. OK, I do - its just maths, but you can't know turbine inlet pressure without measuring it on an individual engine.

http://www.owendevelopments.co.uk/turbos/garrett-turbos.asp

How does it work when you look at the turbine graph - beats me! BTW, I think 62% is like the efficiency islands on the compressor map, not how you used it.

Anyway, the more simplistic way I understand it is that the key is backpressure in the exhaust - once it gets too high the backpressure pollutes in intake charge and you get hotter and less oxygeny (a technical term, surely) air. Apparently 2 valve engines are more susceptible to backpressure, in particular as they need to run more lift / duration to get the same flow as a 4 valve head. Even more apparently, a rule of thumb is that you know that you're getting backpressure problems when the backpressure is more than about 1.5x the boost.

Back on what you said, while a big wastegate might get around (literally) the restriction of the too small turbine, but it might be unable to run a decent level of boost without excessive backpressure, and/or hold boost at higher revs without higher backpressure. The wastegate won't help the fact that the turbine is too small - it opens with boost pressure, not backpressure, so I think the backpressure problem would remain. I reckon it would be stink to drive too - a massive spike of torque at ~2500rpm would be tough to drive smoothly.

So I reckon GT3071R, maybe with the spangly divided housing you can get (basically it ends up a ball bearing GT32). T3 is where its at. T25 too small - potentially even for my 2 litre, although the 0.86 might be a decent compromise. It does, of course, depend on how much boost you plan to run as well.

Happy to be proved wrong on any of this by the way - most of it is also just research and/or thinking about it. I'm aware that SR20's quite happily run GT2871R and GT2876R making good power and seemingly unrestricted by the smaller a/r. They are a 2 litre tho.

Edited August 14, 2009 by CamB

[_BRS_ 199]

Back on topic...

So guess what guys? I got the monster back after work tonight and seriously WHOAAAAAAAAAAAAAAAAAAA!!!!

I am in disbelieve on how damn hard my car goes now haha.. never driven anything like it! Blair dropped me out there and followed me back, my mate also came along for the ride. Stopped in at Blairs before bringing it home.. 1st gear no traction.. 2nd gear no traction and 3rd gear whoa it holds boost upto like 5000rpm then its just all crazy steps out no sweat!

I N S A N E !

Can't wait till all the guards are done and its sitting lower to get some more traction to the ground.

Good times to come!

All the hard work and slaving over this has n e a r l y paid off, altho projects are never "finished".

[Guest FrantiC]

Best be making a video this weekend, Lots of smoke, turbo spooling and that wastegate screaming. Right Luke?