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Discussion Starter · #1 ·
About to purchase R34 GTR and take it to around 750 BHP, I have be talking to Mark at Abbey and he would like to take it down the large single turbo route, I was always under the impression 2 smaller ones would be better, not working as hard and less lag? even though Mark says his have boost from 4000 to 8000 rpm?

would like to know peoples opinion?
 

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Discussion Starter · #3 ·
Cheers, probably go with what Mark at Abbey says anyway obviously knows his stuff and I am not the skyline expert , his good argument any way which is good enough for me is 2 hours to service a single to 10 hours for a twin.
 

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Discussion Starter · #5 ·
a mixture of track and road, no dragging as such, may be the odd santa pod run, but that would be once in a blue moon, mainly to Spa and the Nurburgring as well as the UK track days and not forgeting Sunday blasts, however the car would aslo be used to get to the events.
 

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Single or twin

My advice to you Simon is to drive a big BHP/Torque single turbod car and then a twin turbod big BHP/Torque car and see which one you prefer .

Good luck and let us know which route you'll be taking !
 

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TWIN

Well some one has to say it,
so why not me,
I would go for twin turbos as they offer much much more kick when they come on song, and as far as servicing goes my 28\35s are three years old and still look brand new still havent made an official 750 bhp yet on stock fuel,I still have 84 bhp to go, so good luck
Gary
GT-ART
 

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Discussion Starter · #9 ·
Gary,

You have just give me a dilema, because, so far every body has lent toward the single route including [email protected], however, you say the Twin would be the way to go and after reading the 211mph car section on your site, you obviously know your stuff, I think it will come down to a side by side test in both cars to which one I prefer. but thank you for your input.
 

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Single'd Out

Hi Simon.

I can only comment on me mate Ronnies car with the T78 as I haven't driven a car with big twins(turned down an offer to drive Garys last year, silly me) BUT, suprisingly you don't get a big hit with it as you'd expect but more of a rush all the way from 3600rpm upto the rev limiter (set at around 8500rpm at the mo.) Very tractable.

I was so suprised after driving it because I had heard so much scaremongering about big single lag but never felt that.

Mind you with the electronics available today, and having spent time driving the car while being mapped, thats whats making the difference.

Until we see a car pushing out the reputed 800-900 bhp over here running either a single or twin setup we'll just have to wait and see I suppose.

Ooooh shouldn't be too long. Keep an eye on me posts :D .

glen

ps. I do believe though that all the big drag cars in Japan do use twins but those things are MAD. Foot to the floor and probably dont start pulling till about 6000rpm. Scary.

pps. I do have a T78 on mine but run at a modest .83 boost. Should last me about 25 years then. Might as well have got a mortgage on it :D .
 

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If you've got the money, most of the Japanese tuners I've talked to recommend twins. This is especially the case if you want big hp as the twin setup tends to provide more top end flow for an equivalent amount of lag as a big single (ie. if both turbo combinations came into full boost by 5,000 rpm, the twin would pull longer at the top). Singles are apparently better for mid range punch.

Here's an example. At the all Japan HKS drag meet last year, I spoke to Kawasaki-san (HKS drag race driver) about this topic. He provided me with the following insight. On his R34 (R&D car for HKS) they initally set it up with a T51R SPL and it was making approx. 950hp at the engine at 2.0bar boost. They then simply switched to twin 3037S turbos and they were capable of making the same power at only 1.8 bar boost with similar lag characteristics. I guess this says something about the efficiency of the turbo setup (all other things equal).

Cya O!
 

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An Arguement for both !!

Yeah I agree there is massive scope for both set ups.

Glens single, Garys "Throbbing Purple Monster!" and Garys Purple car.

I'd go for a single purely to be different !! Whether it worked or not. But then you are talking to a guy who only built an engine on the proviso that I could fit stainless manifolds to it cos I think they look nice.

Gary.

Thats the second sensible post I have done now !! Must be growing up or something !?!
 

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Discussion Starter · #15 ·
I have to say in the past, I would have argued till I was blue in the face for the twin route, I would have thought there was more scope for power and they wouldn't be working as hard as the single unit, having spoke to Lee Noble(man behind the Noble M12 GTO, Ultima,Stealth B6) obviously someone who knows about cars, thats one of the reasons why he went for the twin garrett, T25 watercooled setup in the Noble M12. But now having listened to the single route argument, they certainly put a good argument forward, so decisions :confused: :confused:
 

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well i am glad i posted

This has caused a sensible debate,
TWIN in my opinion is better, on my car I have seen boost made at 4000 rpm = to 0.6 bar at 5250 it makes 1.8 bar and it holds that steady untill 10500 rpm, i have also run 2.1 bar but it made the chassis twist in a straight line,
I am currently rebuilding my engine to a revised spec, but keeping all of the hardware as was it will be interesting to see the results as i am hopeing to achieve another 50 bhp and a increase in torque, I only ever run OPTIMAX and i feel this is the most i will reliably achive without octaine booster or race fuel, If , I ran race fuel in my car as was, would make over 800bhp no sweat.
If you want to run a fast road going R34 that is reliable and very drivable, start with suspension, brakes ,and wheels and tyres first,then the engine and clutch etc you only need a true 600 bhp and i mean a true 600bhp, that package will be dangerouse and leave your adrenilin pumping for hours every time , EVERY TIME, you drive it, as i think thats what you are looking for.
This will also be reliable for a long time if all the good oils are used,
I could use my bearings again if i wanted to, and they have done 20,000 mls, so reliability can be achived, mine BROKE due to a block failure but i got 3 and a half years out of that,it was pourous and i knew about that 2 years ago, rad weld is good stuff,it saved me money for 2 years , it allowed me to carry on mapping etc, cos if it blew up it dident matter as the block had to be changed anyway, DEVELOPMENT WITHOUT COMPROMISE thats what i have done.
I am glad i seem to be backed up by japan tuners theory two is better than one it is all due to EXHAUST FLOW simple 2 flow more than 1:D
Gary
GT-ART
THE FUTURETIVE:D MY CAR WILL BE READY SOON,
 

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Agree

Yeah agree with you Gary on the point of too much bhp can seriously damage your health on the road. Having driven Ronnies in the early stages of development I can tell you that the 680bhp his car was knocking out is MORE than enough for the road and track days. Where the twins may lose to the single is the cost elements. Why spend more for 2 when the job can be done with 1. The T78 on Ronnies car is producing 1bar of boost at 3600 rpm which I've got say again I found phenomenal to drive.

The big boy tuners go for Big Twins as they are after max bhp in a straight line with no consideration for torque and like someone said they just want to shift a huge volume of air. I've never seen a Skyline race car running huge twins?

And also what is good for the track specifically may not be good for the road.

I think I get the idea of where you are coming from Simon and the choice is really and truly yours and dependant on how much you want to spend the answer is out their. Whatever you choose though make sure it has a compromise built in to it.

See Ya.

glen

ps. Might get you a ride in Ronnies if you want ;)
 

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Dyno sheets at dawn

The lag debate can also be described as the low RPM torque debate.

The tuning section http://www.gtr.co.uk/Tuning.html has some dyno results from earlier runs at Tuning Japanese and may not show the correct scenario as of today - but the torque figures for the two big BHP cars under discussion at 2000, 3000 and 4000 RPM are as follows.

Gary - twin HKS 2835 123, 128 and 167 ft-lbs torque.

Rupert - single T78 127, 152, and 224 ft-lbs torque.

I know which one I'd rather drive.
 

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Discussion Starter · #19 ·
well I know what you are saying, I have seen and heard about cars in japan producing 1200bhp, they even struggle to keep them in a straight line, never mind going round a track, or down an British road, probably the car will not be running full boost every time and the actual set up on the car I will be going for will allow set up for individual tracks (ratios change with the holiger sequential box, suspention set up etc) plus the right amount of bar for the track,very much like a race car, because too much power could and would leave a slower car, any one familiar with evo magazine tests around croft will see a 230bhp Caterham R500 run rings around much more powerful cars.

As for the buzz, I have a few cars in my garage that on the right road leave a permament grin, even just flooring the F355 and hearing the 3.5 V8 screaming :D :D :D, just sends a shiver down my spine thinking of it, I want the car to be the ultimate skyline in the uk, quick around tracks and on the road, but not so as it is undrivable, I want to quensh my thirst for power, to finally say thats Perfect. Alot to ask for I know, but I am sure it possible
 
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