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600 BHP - Which is quicker, Single or Twin?


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Welcome to the site Ken :thumbs:

 

Not sure I agree on the twins vs. singles route, especially given power goals over here tend to be typically around 600bhp fly. A modern single would appear to spool quicker like for like over the twins as well as being more practical / cheaper in terms of packaging.

 

I also don't buy that twins are so much better on the road than they are on a UK dyno (US dynos tend to be the unbraked inertia type only good for pub bragging rights power figures). You have to remember, if your twin car produces less boost on the dyno than on the road, it's because the braking load on the rollers is less than typical road resistance meaning the engine doesn't work as hard thus less boost. This is exactly the same for the single turbo'd cars!

 

Cheers,

 

Brian.

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Guest Ryan0594

KenHenderson,

Two lovely cars! It's nice to see non-stock cars that have been tastefully tuned instead of the usually crass spoilers, decals and the like. May I add: where you took those photos is beautiful!

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Guest KenHenderson

Thanks to all for the very kind words about my cars. They are very much appreciated.

 

 

Welcome ken. keep posting. its much more friendly here than that other site :p

 

That certainly appears to be the case. I definitely intend on establishing roots here.

 

Welcome to the site Ken :thumbs:

 

Not sure I agree on the twins vs. singles route, especially given power goals over here tend to be typically around 600bhp fly. A modern single would appear to spool quicker like for like over the twins as well as being more practical / cheaper in terms of packaging.

 

I also don't buy that twins are so much better on the road than they are on a UK dyno (US dynos tend to be the unbraked inertia type only good for pub bragging rights power figures). You have to remember, if your twin car produces less boost on the dyno than on the road, it's because the braking load on the rollers is less than typical road resistance meaning the engine doesn't work as hard thus less boost. This is exactly the same for the single turbo'd cars!

 

Cheers,

 

Brian.

 

Understood, this is an age-old discussion for some, although the SAE papers that have been published by Garrett/Honeywell and Porsche, Nissan and Audi, to name a few, all draw the same conclusion that, like for like, two smaller twins will perform better than one larger single.

 

There appear to be some UK member assumptions about dynos in America. In many respects, we get the same comments from Aussie members. All of the top Supra tuners, like mine, have either either the Mustang dyno or one of the last three versions of Dynojet software that allow the dyno to loaded appropriately for tuning sessions and the like. My tuner has both the Mustang dyno and a Dynojet with the latest software. Since dyno numbers grab the most attention, there is the assumption, erroneous IMO, that bragging rights is the primary focus. While it's clear that a big number is more important to some than others, no matter where one hails from, the implication that dyno numbers are not genuine because they are so high or because of the type of dyno used is unfounded, IMO.

 

When one does the calculation of what it takes to run a 7.91 quarter mile, trap at 190 mph or obtain a terminal velocity of 246.xxx mph in the standing mile, you will see that such times and speeds directly correlate to the dyno numbers posted. While such numbers are not common elsewhere in the Supra world, I believe the proof is in the (racing) pudding and such proof generally aligns itself with some of the more advanced horsepower calculators one can find on the internet.

 

All that said, I believe these topics (twins vs. single; dynos) are of the agree to disagree type that are fairly common in the arena in which we find ourselves.

 

What sort of spec is Eau Rouge running Ken. You are a very lucky man have two very sweet supras

 

Eau Rouge is my occasional DD BPU (with all the plusses) car. Off the top of my head, she has OEM turbos, FMIC, HKS downpipe, exhaust and F-CON V Pro EMS, Fluidyne radiator, HKS EVC VI boost controller, HKS Mixture Controller, HKS DB RS auxiliary meters, Do-Luck Rear Cross Brace, Do-Luck aluminum Floor Assist Bars, TRD motor and tranny mounts and Brembo brakes front and rear, with Ferodo DS 2500 brake pads.

 

On VP 109 Motorsport unleaded race fuel, she makes 422 whp and 437 rwt at 19.3 psi. On 91-octane pump gas, she makes 387 whp and 396 rwt.

 

Thanks again everyone for the kind words.

 

Ken.

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I also don't buy that twins are so much better on the road than they are on a UK dyno (US dynos tend to be the unbraked inertia type only good for pub bragging rights power figures). You have to remember, if your twin car produces less boost on the dyno than on the road, it's because the braking load on the rollers is less than typical road resistance meaning the engine doesn't work as hard thus less boost. This is exactly the same for the single turbo'd cars!

 

Cheers,

 

Brian.

 

Your right on one thing, all turbo cars produce slightly less boost on the dyno than on the road, but where the big twins suffer is with building boost.

 

My car has been to SSR many times and I have spoken to Charlie about the difference in the dyno graph to how the car drives on the road. He informed me that the dyno does not load the car as much as driving it on the road and my car will suffer more from this than a single car, even of the equivalent size turbo.

 

Having 3 cylinders running each turbo requires more exhaust gases to get the turbos going, so this raises the boost threshold a fair bit on the dyno.

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Hello Ken :wave: Good to see you here, and thanks for your sizeable first contribution.

 

I've always heard that, like for like, two smaller turbos is better than one big one. In my contributions to this thread, I wasn't at any point arguing that one big turbo is better than two smaller ones. I was just saying that the pair on Lee's Supra seem too big for the rev limit/motor/setup, as they don't start blowing hard until the last 1000rpm or so. That's based on the info supplied, which to be fair is all I could go on (beats making it up ;) ). Just thought I'd clear that up.

 

I think most of us go for a single tubbie for cost and simplicity reasons. The packaging is easier, our steering wheel is on the correct side :p so a twin setup is even trickier to fit, they cost more etc etc and for most of us, 500 to 600bhp is more than enough for our roads and big brother fun police. It's our sensible British reserve ;)

 

Getting traction off the line at Santa Pod is no real test of a turbo either, a much large factor is driver skill and experience I suspect. I hear that terminal speed is the big indicator of overall power, though.

 

-Ian

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Love the pics Ken, you have 2x very tastefully done Supras! :thumbs: Think my ideal would be Eu Rouge in Black :shrug: lol (I love stock body with nice wheels)

 

Having 3 cylinders running each turbo requires more exhaust gases to get the turbos going, so this raises the boost threshold a fair bit on the dyno.

 

So by implication you are saying twins are harder to get going... which to me also implies they are too top endy for typical UK goals. The graph overlays seem to support this. I hear what Ken is saying about 2540's being more sensibly sized twins but when all factors are considered the likes of a T67 DBB on stock cams is hard to beat when thinking of availability of decent priced off the shelf kits and bang per buck that gives you a very nice to drive, hard hitting street car.

 

Not sure on the whitepapers mentioned - would have to read them to make any real comment but anticipate the context is very different to use in a fast road setup on a Supra with a power goal around 600bhp fly.

 

Yes Ken's twin car puts out some seriously impressive numbers but personally can't help but feel on the average UK backroad (certainly on most of the Scottish particularly winding roads) that the better weapon would be the setup I've mentioned above - area under the curve and all that!

 

I'm sure in the states such a car makes waaay more sense given the roads and block layouts you tend to have over there.

 

Cheers,

 

Brian.

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