I was musing today about where I want to head with my performance modifications and a few questions came up regarding possible turbo setups.
I like the twin setup because I like having the power early. Moving to a big single (e.g. T51) sacrifices that low end power.
Having a medium size turbo (e.g. 2835) that spools faster sacrifices top end.
Soooo, why not have twin medium size turbos? Fast spooling (compared to the big snail) and a big hit.
Is this sound reasoning?
Is the only thing that stops people doing this the obvious price tag comapred to a big single?
Am I worrying over nothing in regards to the spool up time of larger turbos? - When does a T51 come fully on line - 5000rpm? What about a 2835?
I\'ve read about an FD running twin 2835\'s that produced 478rwhp (with street port).
Ta.
Chris.
I have twin mediumish singles on my 96 fd, see attached thread. :-) which has been dynoed at 405 rwhp!
I would say it has been a pain in the @rse plumbing them and getting sufficient clearence, but it seems to give the desired result.
http://www.mazdarotaryclub.com/forums/showthread.php?s=&threadid=11785
I agree with you Chris and personally like the twins, but a single would be more economical if that is a factor in your mind. With the right porting I would think that you would be able to spool up a big single turbo earlier than 5krpm but doubt it would be any earlier than 3k.
Again I\'m guessing here, but I would guess that big single would also be cheaper. medium twins would mean a lot more complexity in the plumbing (especially if you want to keep them sequential) and perhaps more tricky space issues. Issues in my experience invariably don\'t go away till you throw yet more money at them.
Gregor
It was this setup which got me thinking: -
http://www.urbanracer.com/articles/anmviewer.asp?a=843&z=16
chris : I assume yours is non-sequential? How do your hybrid\'s compare to the standard Hitachi\'s in the FD?
Comparing your dyno sheet with mine regarding spool up: -
Revs : hybrid (non-seq) (rwhp) : Hitachi\'s (seq) (rwhp)
2500 : 50 : 70
3000 : 100 : 110
3500 : 125 : 150
4000 : 180 : 170 <-- hybrid\'s overtake Hitachi\'s and power off into the distance...
That tells me they spool up pretty quick.
Do you have any pics ;)
Problem with spooling two bigger twins is the flow of the engine. It just doesnt flow enough to spool them faster as the equal sized(2x) single turbo.
I think you can have the best of both worlds with turbo spool up and good tope end power with a single turbo. Depends on the whole package.
The white single turbo I had was a to4r turbo with.84 a/r housing.
max power was 424 rwhp running way to rich still.
2500 rpm 60 rwhp
3000 rpm 100 rwhp
3500 rpm 135 rwhp
4000 rpm 180 rwhp
which is pretty much the same as you guy\'s
rgds
It seems that the first 4000rpm are the critical ones, but as you say Brian, they are all pretty much the same up to this point. I\'d like to see the dyno results for the twin 2835.
I\'m feeling more confident about the single turbo as the best all round route to go down.
You after this sort of thing??
http://www.rx7store.net/index.asp?PageAction=VIEWPROD&ProdID=885 (http://www.rx7store.net/index.asp?PageAction=VIEWPROD&ProdID=885)
Yep, that\'s the kind of thing, good find!
Hi Brian
Just out of interest buddy, was or is that engine ported, and what kind of boost is that running.
Thanks
QuoteOriginally posted by <--rYaN-->
You after this sort of thing??
http://www.rx7store.net/index.asp?PageAction=VIEWPROD&ProdID=885 (http://www.rx7store.net/index.asp?PageAction=VIEWPROD&ProdID=885)
Mmmm, less than £2k at current rates! I\'d think that the downpipe might not fit on a right-hand drive car though...
Quite honestly I think a well set up single [read well tuned] is by far the best way to go, there are a number of peeps who have had a go but unless you run them sequentualy you wont make any low down grunt, and, we all know about the rats nest and resultant problems that come with it. I cant see a medium pair of twins spooling up much faster than a good sized single, besides look at all that extra weight and engine bay bling you would have to polish:rollin
Quotehttp://www.rx7store.net/index.asp?PageAction=VIEWPROD&ProdID=885 (http://www.rx7store.net/index.asp?PageAction=VIEWPROD&ProdID=885)
For 400 at the wheels I\'d just go with a single HKS or Trust kit or a GT35R. Those twins probably look cool but I cant imagine they are going to spin up any faster off one rotor each than a single of greater size being pumped by both rotors? For all that hassle I\'d want bigger HP potential too personally :)
QuoteOriginally posted by jetpilot
Hi Brian
Just out of interest buddy, was or is that engine ported, and what kind of boost is that running.
Thanks
Yeah engine is well ported. it was 1.1 bar when it was dyno\'d but it\'s now mapped to 1.4 bar
rgds
A good twin set works better than a big single in my opinion and ive ran both. For a big single to work up top it has to run a big exhaust housing, around 1.06 or 1.22 Q trim, which means no matter how well tuned it is, you wont see boost below 4500rpm. Drop the exhaust housing size to bring boost on early and you will just strangle it up top.
We went to a twin 700hp [gt35] roller bearing set up with relativly large .63 exhaust housings, it still boosts much earlier than the single and has similiar top end. For a streeter i would run smaller exhaust housings on a twin turbo set up.
Marty
Hi Marty,
thans for the info, you confirm what I suspected earlier to be the case. The primary purpose of the car would be street driving. Do you have any more info on the twin GT35 setup? Was it hard to setup and troubleshoot? To achieve 700hp (is that at the wheels?); did that involve some large porting only the setup I saw (see above post) only achieved <500rwhp?
Thanks
Chris.
To run 500rwhp in street trim wont be easy, the fuel used will be the biggest problem. The TT ehgine is bridgeported and runs on Methanol, it has made 920hp at the flywheel on the engine dyno. If someone wants to host the pics of the engine i can email them over.
We had no real prblems setting them up, only minor problem was one turbo would want to stall when you jumped off the throttle, this was easily fixed by changing to a bigger blow off valve fitted in a different location. Its an amazing set up, even with the big exhaust housings it comes on boost easily and the top end is totally out of control! Once when the gearbox didnt shift it reved to over 15,000rpm and went on to run 169mp/h over the quarter.
With smaller exhaust housings to tone it down, it would be awesome on the street.
Marty
Hi Marty,
just PM\'d you about arrangements for hosting the images and getting them the right size etc, or you can follow the instructions on this thread (http://www.mazdarotaryclub.com/forums/showthread.php?s=&threadid=10026) for posting them yourself.
Eager to see those pics :)
Chris.
Images of the >900 fwhp twin turbo setup courtesy of Marty.
I can\'t even imagine the cost of this setup?
Is a bridgeported engine streetable?
Running methonal is a bit extreme for the street too, what could we expect from pump fuel?
.
.
.
nice but unless u are donald trump or the like u will never afford to build and run this kind of set up and it would be i think totally unusable for street..i am by no means an expert but anyone who tunes whether for cost or power goes single.my gt35/40 spools from about 300rpm and certainly doesnt run out of puff at the top end.another thing with twins is the heat issue all crammed into what is a small bay anyway...if u want power and good spool then consider the gt35. chris i dont think the small increase and it is only small increase in lag will be noticable
If I was minted then hell yeah, but realistically their isnt any one in the UK with the pockets for a twin (35R?) 13B like that - I hate (love?!) to think of the spec on the motor...plain evil :D
The manifold and plenum is interesting. The TB on the opposite angle to the plenum - for a reason I\'m sure. I imagine my plenum to be very similar - but with my TB aligned more toward the passenger front light.
Its a beautiful looking thing, been one of my fave 13B pics for a long time :)
QuoteRunning methonal is a bit extreme for the street too, what could we expect from pump fuel? [/B]
Carnage...and lots of it! :)
Cost for the engine is apx aus$30k outright. That includes engine block, fuel pump, intake and exhaust manifolds, roller bearing 2 piece crank, turbo,s and wastegate.
Over here the fuel is rubbish. Anything above 400rwhp is going to end in tears sooner than later.
Ive ran this engine with the single turbo in the FC photos, and the current TT set up. Personally i prefer the twins, however the brains behind it all. Phil Laird wants to go back to a single set up.
I guess after we run it next i will know for sure. But as for driving around the pits, give me the twins any day!.
my setup is coming along, almost complete
Very nice! Keep us updated!
QuoteOriginally posted by 20B_boy
Its a beautiful looking thing, been one of my fave 13B pics for a long time :)
Yeah you and me both:cool does it come with boxes of tissues:rolleyes:
Gary has a similar set up [turbo wise] would be interesting to see what power that makes.
Chris [sense tuning] has built a tt that made good numbers [400+atw], but like you guys for the street a single is the way to go.