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Post by daywalker76 on Sept 18, 2011 1:53:26 GMT
has anyone tried fitting a turbo to a rocket. i know room in the engine bay is pretty tight so i was wondering if theirs any room.
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Post by mabbs on Sept 18, 2011 8:11:03 GMT
Hi,
Their is enough room for a turbocharged engine. I think their may be a build using an Mk 1 RS turbo engine in the make. RTR can pretty much fit anything into the engine bay you require.
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Post by flynn on Sept 18, 2011 10:24:47 GMT
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Post by markinireland on Sept 21, 2011 11:18:14 GMT
I'm going to be putting a Saab 2.3T engine and box in.... if it can be made to fit. Taking empty block, head and gearbox shell down next month to get a better idea of available space...it will be tight but fingers crossed. ;-)
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Post by Stiggy on Sept 21, 2011 15:12:17 GMT
It would be helpful to learn of the proposed torque at the wheels. Building a car is not just about "does it fit" We must consider the design of the chassis and associated suspension components first. I have got structural calculations for the chassis that was subjected to vigorous testing up to given powers and available torque. If one is able to put excessive torque down (which is doubtful in such a light car) then we need to consider all implications before commencing with the project. Best to let me know first. I will then give it careful consideration.
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Post by markinireland on Sept 22, 2011 7:13:05 GMT
Hi Stuart, Understand where you are coming from and appreciate the saab setup will more than likely have to be reined in somewhat. However, this is a very easy process with the Saab ecu software, and the torque curve can be adjusted to suit. The engine I have, in its current build state dynoed 446lb.ft at 3500rpm and will make about 370hp, I then reduced the boost down to 1.6bar which dropped max torque to 400lb.ft which made the cars road manners a bit more controllable.  The ecu on the car at that time wasn't as flexible as the newer saabs, this next dyno print out is from my current daily runner/trackcar and the torque curve is more restrained to assist tyre traction.  Hope the above info helps. Cheers, Mark |
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Post by Stiggy on Sept 22, 2011 9:53:44 GMT
Very impressive figures, you need a chassis specifically designing for the purpose.
If you put some wide sticky tyres on the back in the dry the forces that could be applied to the rear suspension are potentially immense. There would also be a lot of power that could not be used and higher top speeds are not what the car is designed for either. Sorry to damped your enthusiasm but I feel this car would be dangerous to drive on anything but a runway, there is no point in having that much power in a 500 kg car. 250 bhp is a very fast Rocket in the right hands. 170 is more than enough for the road. A standard 115 Focus 1.8 is a quick car at over 200 per ton.
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Post by dinosaurjuice on Sept 22, 2011 10:03:15 GMT
hi mark, just out of curiosity, have you been for a ride in a rocket yet? probably worth doing before deciding which engine to use. will  |
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Post by markinireland on Sept 22, 2011 11:32:57 GMT
One of the reasons I'm interested in going down this route is know my way around the saab hardware, the parts are cheap, the engines are bulletproof and don't need anything changing internally to run 500+hp....the mileage on the 1st dyno chart was 200K and the current car graph at 400hp was when the engine had 286000 miles on it. I've been following Mabbs build on the forum and the fantastic work he has done to the car and his engine hopes to deliver over 300hp....I could bring my engine tune down to similar figures by sticking the original turbo back on and running base boost.  However, I could also use a 2 litre engine which would reduce the torque produced but still give an easy 300hp at the top end and it would probably cost me less than the price of the supercharger Mabbs is fitting to his engine. |
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Post by mabbs on Sept 22, 2011 18:29:23 GMT
Wow that is some power  My 2p worth. I did look at going turbo charged but was strongly recommended not to in a transverse vehicle due to the spike in power from the turbo. The Rotrex supercharger has a progressive power/torque gain so can be driven (pending driver  ) smoothly. The other issue due to the power spike from a turbo is the stresses this can cause. 500 bhp (and over 400ft/lb torque) in a 500kg car has been done, so it's possible - Ariel Atom 500 V8, Caterham Lavante, but these were designed for that power to weight and the engine progression of power/torque in both cars is very linear. Shoot me down if I am incorrect but this is the way i see it  If it's cost effective and can be done then do it, but would be very scary and possibly dangerous to drive in the wrong (certainly my) hands. |
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Post by Deleted on Sept 23, 2011 14:02:06 GMT
Mabbs, it is true.. However, correct use of compression ratios, and turbo size, can give a nice linear power/torque curve. I myself have run daft power on a FWD drag car, and by managing boost curves and restricting power, saved a fortune in gearboxes and clutches. Yet, still achieving good results. Rotrex is an awesome piece of kit, but pricey!
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Post by andychalmers on Sept 26, 2011 13:58:58 GMT
I had a Sierra cosworth, was only running 280bhp back in the day however it was crap to drive anywhere near fast in the dry, in the wet it was lethal. I spent more time facing backwards on a roundabout etc than the propper way lol. It was fun at 1st but got very annoying. It was all about the power delivery, soon as boost cut in you lost grip, simple. Was too aggressive but as you say nowadays you can have programmable boost controllers etc to smooth the curve etc.
Also dont forget you will need to make some custom driveshafts as Im guessing the Saab ones wont fit, if you weld 2 shafts together they will prob not take the power. My custom rally car shafts cost me £600 each.
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) smoothly. The other issue due to the power spike from a turbo is the stresses this can cause.
