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Sequential turbos...BenzBoy
@benzboy
Club Retro Rides Member 7
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Right, I've been thinking about the turbocharging situation on the Merc V8 (not that it's built yet...  ). I'm not sure which route to go down. I'm kind of liking the idea of a sequential turbo set-up - one small turbo for low-down boost, and one bigger turbo for boost once it spools up. Although I've heard that these things are hard to get right and can cause headaches (I don't tend to listen too much to these kind of comments 'cos half of the people spouting it are just repeating what they've heard...) I don't know whether the turbos have to be one after the other in this set-up or if I can stick the small blower on one side and the big 'un on the other (that would make life easier!) For the sequential set-up I was going to use a little KKK K14, and a bigger Toyota CT-26 turbo I liberated from a Supra  The other option is to use two small K14s (easier exhaust manifold fabbing methinks!) OR just use the Toyota turbo on its own (a bit complex as it's a V8 but could be done...) and have a single turbo V8. This idea came to me after looking at an Impreza turbo set-up on the boxer engine, which runs a longer manifold pipe on one side to join up to the turbo on the other. I'm not looking for massive boost, as the CR is 8.5:1, so anything over 6-8psi might cause a few probs. Does anyone have any suggestions at all? |
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I don't see the sequentials working unless there are two manifolds which rather defeats the purpose.
And a single big turbo will give better preformance than two small ones. I think LPG is a better idea, half the price of petrol and burns at 114 octane. Its a no brainer.
BTW turbos turn into restrictors at high rpm.
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Sequential turbos...BenzBoy
@benzboy
Club Retro Rides Member 7
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Good thinking about the LPG - I could in theory run more boost then. A conversion will have to be a future project though, as I don't have the cash for that sort of thing  . Super Unleaded will have to do for now! I am leaning towards just sticking the single CT26 turbo on - the plumbing will be less of a conundrum for a start, and I'll be saving space. The engine in (stock form) redlines at 5500rpm or somewhere near, so hopefully the blower won't restrict it too much at that engine speed. I just have to figure out the manifolds - probably bringing both of them towards the front of the engine and into the turbo (space permitting!) - that way I won't have unequal length headers which might create even more problems! The I have the dizzy to think about - stopping that advancing.... oh god if I give it too much thought I'll never do it! |
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GrumpyOldMan
Part of things
Addicted to unreliable cars ?!
Posts: 182
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If you use a large turbo, fabricating a manifold will be a real pain, but setting the whole thing up will be easy.
If you use two smaller turbos, fabricating the manifolds will be very easy, but setting the wastegates correctly may prove troublesome.
Performance won't differ much, as your engine is a HUGE Merc V8, which means that low-rev torque will never be a problem.
If you use both a big turbo and a small turbo in-line, all I can do is wish you good luck. Japanese manufacturers have used such a setup in a few cars, but IMHO they were very complex and not really suitable for a DIY project.
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Sequential turbos...BenzBoy
@benzboy
Club Retro Rides Member 7
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Thanks for the replies fellas. I'm getting more and more convinced that the single turbo is the best way to go. The manifolds will be a pain in the as$, but never mind! I wasn't too happy with those K14 turbos anyway, as I learned from Mr_Bo11ox that the turbine housing isn't made to deal with hotter petrol exhaust gases (they were from a diesel). I have soooo much to do before I get to the turbo though - the engine is stripped now, and I have to clean / replace parts and rebuild it all *sigh!* What are the chances that I'm left with a jar full of "spare" bolts and things when I'm done?! |
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I defo wouldnt do the sequential thing. too complex. Here at Garrett we're only just getting to grips with it ourselves!
have you got your megasquirt thing going yet?
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1972 Fiat 130 1985 Talbot Alpine 1974 Lancia Beta Saloon 1975 + 1986 Mazda 929 Koop + Wagon 1982 Fiat Argenta 2.0 iniezione elettronica 1977 Toyota Carina TA14 BEST CAR EVER!!!!!!!! 1979 Datsun B310 Sunny 4-dr 1984 Audi 200 Quattro Turbo 1983 Honda Accord 1.6 DX GONE1989 Alfa 75 2.0 TS Mr T says: TREAT YO MOTHER RIGHT! |
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Consider my intrest piqued ,.. ! |
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Sequential turbos...BenzBoy
@benzboy
Club Retro Rides Member 7
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have you got your megasquirt thing going yet? :-[Not yet. I've been stripping the engine down, but I really should make a start on the ECU... I really want to get the engine some way towards being in one piece at the minute. I'll have to pull my finger out though, cos the Hyundai self-destructs at the end of April (well the tax runs out and I don't wanna re-tax it....) I wasn't sure about the sequential turbo thing - you know how it is, a lot of stuff on the net is just hearsay but now it's come from trusted sources, I can leave it well alone! ;D |
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Supercharge it  ;D |
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Sequential turbos...BenzBoy
@benzboy
Club Retro Rides Member 7
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I'd LOVE to stick a nice big supercharger on there, but they're too expensive for me at the moment  . It'd be more "in keeping" with the Mercedes theme as they use Kompressors a lot, but unfortunately my budget (about £25 at present! ) won't allow it. I've built up a stockpile of turbos though, so I might as well use one! When I saw the size of that Toyota turbo I couldn't pass it up. |
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Yeh I know where you are coming from BenzBoy - turbos seem pretty much ten a penny, being strapped to many european and japanese cars and to virtually every diesel. I just thought it would be easier to go supercharged as i'm sure there'd probably be a bolt-on kit available from the States - or at least something which could be adapted  And would negate the obvious problems associated with turbocharging - the plumbing requirements, underbonnet temperatures, boost threashold, turbo lag, etc etc However Turbocharging your Merc - if you do the work yourself could be super cheap and far more satisfying as a result - but you know that already |
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).
. Super Unleaded will have to do for now!
;D
.
And would negate the obvious problems associated with turbocharging - the plumbing requirements, underbonnet temperatures, boost threashold, turbo lag, etc etc