Page 1 of 2
turbos: TB's / Carb / Injected?
Posted: 29 May 2008 02:39 pm
by stuartB
RE: Throttle bodies / Turbo
Im talking about a set of old second hand bike Tb's or carbs, whatever i can get my hand on that'll work
certainly not going to buy a new set. what would you use as carbs for a turbo? the oringinal single carb or twins, or what?
I know the exhaust manifold off the 940 turbo fits, and getting hold of a turbo and having it rebuilt is not going to cause any headache for me as 'turbo pete' can sort that out... actually it IS just the carbs/Tbs i was unsure of.
what does the 940 use for the carb? maybe i can just pinch that as well...
OR i could stick the Webers on i s'pose... mine were £150 for the pair (straight off a formula4) but they need a rebuild so thats another 30 quid i guess
Posted: 29 May 2008 02:57 pm
by Jason B
I'd steer clear of carbs if you definitely want to go the turbo route as it'll cost just as much as injection and will give you lots more hassle trying to get everything set right. With regards to fuel efficiency, you are wanting much more power hence fuel efficiency really doesnt factor into it surely (otherwise the title would be about a smartcar engine conversion). ITB's are a great setup but are they worth the cost without fully mapable spark and fuel, as opposed to one of the current volvo injection systems lying in scrappies everywhere. - It's possible to make big power out of reletively cheap stock volvo parts.
Posted: 29 May 2008 03:59 pm
by stuartB
Food for thought, definately.
I was thinking that electronic systems would be too much money/time/ballache but as you rightly point out, they are sitting in scrapyards everywhere.
I dont need silly power anyway so i wont be camming and reprogramming, at least thats not the plan, i just want more power on tap.
whats the loom like? i work in electronics so i'm fine with piles of wires, I just need to know if i can splice it in to what i have already, or whether i would benfit more from using the whole loom from the donor
Posted: 29 May 2008 07:42 pm
by jtbo
It is not that hard route

Posted: 29 May 2008 08:16 pm
by Jason B
I know, I'm with you on the megasquirt plans - but its not the same kind of quick straightforward solution he's thinking about (unless I'm wrong), as I know that if and when I go that route I will be having a major sort out of all the cars wiring etc as it would be silly not to.
Posted: 30 May 2008 06:07 am
by Ozbrick
Posted: 30 May 2008 10:14 am
by stuartB
Correction:
Turbo and carbs is what i meant..
Sorry, getting confused with another project one of my friends is doing. He's got twin throttle bodies for his twinpoint mini, and the CARBS are for the volvo.
basically Im waiting till he's done it so we know what we're working with, then the same is being done to mine...
topic to be adjusted accordingly

Posted: 30 May 2008 12:15 pm
by Chris_C
Surely the having the turbo negates the point of having indi carbs or ITB's? Unless you are going to have ITT's too

Posted: 30 May 2008 04:48 pm
by stuartB
Ok now you've lost me, sorry
ITT?
Posted: 30 May 2008 06:16 pm
by Jason B
lol, what he means and what I was hinting at in my first post is that itb's while cool are silly if you are just going turbo as you need to force air into the engine so the inter-cylinder balance (the main point of one throttle per cylinder) is nowhere near as important anymore because you are just cramming air into them all equally. This leads nicely to the fact that throttle bodies or carbs don't make the turbo plumbing easy at all as you will need to fabricate a special manifold with so that you can create the pressure to force air into the system, so really by sticking some ITB's onto this "air box" you aren't gaining anything over a regular injector setup. Though it has been done on a few expensive japanese drift cars. Chris's joke was basically saying that they won't strictly be ITB's if you did it this way and that to be proper ITB's you'd need one turbo per throttle hence "?Indvidual Throttle Turbo?"

Posted: 30 May 2008 07:45 pm
by Chris_C
Yeah, as Jason said really.
Normal way you'd have a turbo with an injection setup is air filter, turbo, intercooler, throttle body, engine. The whole point of ITB's is to separate the individual inlet ports so that you can get perfect (hah) tract length for standing waves etc to work (I think, I've never looked into it, but the intertrons will have much info, the reason is pretty much the same as why you'd fit DCOE's over a single carb).
However, for a turbo to work, the entire system has to be sealed, you can't just have the filters at the end of the trumpets anymore. So, the only way I can see you being able to fit ITB's with a turbo, is have 4 intercoolers, and 4 turbo's, hence the ITT's (indi throttles and turbos

)
Injection (closed loop) works a lot better with turbos that carb's do, as you can place the carb pre or post the turbo I believe, though trying to fuel correctly like that sounds a nightmare. With closed loop injection, you have an air mass meter or air flow meter, and it will dump in the correct fuel

Posted: 31 May 2008 12:03 am
by Cloud
Throttles AND a turbo would be a setup nightmare not just the fuelling but flow from the turbo into the carbs is going to be hard to get even, the power potential is there, without a doubt, but flowing that much air and fuel into the engine even at relatively low boost pressure could rather easily make it go bang. I'd choose one or the other. A dirty great turbo or a highly efficient flowing set of carbs and some head work.
or buy a wet manifold Nitrous kit and use some 100bhp jets....350-400 quid. Power when you want it. The stuff is relatively safe too, Nitrous itself isn't combustible until its mixed with fuel or oil etc...no less safe than an LPG conversion. I'm considering it

Posted: 31 May 2008 12:28 am
by Jason B
I would love to see a 300 with nitrous! - not something I'd ever want to do myself but it would be awesome to see. Only the wizards of nos systems are insureable in the uk though iirc.
Posted: 01 Jun 2008 03:21 am
by Ozbrick
Nissan Skyline GTR's RB26DETT has ITB's and twin turbo's, that's why it has such brilliant power delivery for it's small capacity.
Posted: 01 Jun 2008 12:59 pm
by germ
small?
