MK2VR6
Posted a lot
Mk2 Golf GTi 90 Spec
Posts: 3,329
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I've got this mental idea of getting an RX8 with shafted engine (plenty of them out there) and getting a BMW TDS diesel lump dropped in. Both are rear wheel drive. Before I get the "Buy a diesel car if you want economy" quotes, here's my logic... RX8 prices are seriously low at the moment. They average anything from 15mpg-25mpg, so are curse word on fuel. I personally really like the design of them for a 'modern', but would want better economy and greater reliablility. LPG conversions on them are not easy and not a good idea on a fragile engine. Realistically, what sort of ££ am I likely to incurr asking a petrolhead with skills and a workshop to do the conversion and fabrication if I supply them with car and engine? Any ideas? Have an RX8 and it's predecessor, the RX7.
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I can see, and understand, your logic. It'd certainly have the "WTF factor".
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Copey
Posted a lot
Posts: 2,845
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if you cant DIY it i wouldnt bother, would cost you a STUPID amount of money to pay someone else to do it!
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1990 Ford Sierra Sapphire GLSi with 2.0 Zetec 1985 Ford Capri 3.0 (was a 2.0 Laser originally)
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rodney
Posted a lot
https://www.facebook.com/RD-vehicle-transport-and-recovery-services-525622614268010/
Posts: 1,677
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only problems id see would be the wiring side , the tds as shared in the omega and range is a good engine , need to get a doner car id say and break the engine loom down , these also chip well too,.
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facebook: rodney dean / rd transport
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stealthstylz
Club Retro Rides Member
Posts: 14,926
Club RR Member Number: 174
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You'd never get the cost of the conversion back if you paid somebody to do it for you no matter how many mpg's you gain. I like the idea though I keep running a Isuzu 1.5td into mx5 swap through in my head
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Nice idea but probably not feasible to use a BMW engine. The Omega lump is a straight 6 so probably too long. The 320 engine is gutsy but a neigbour had one last year and money pit that he still didn't get sorted as turbo then started to fail. Also I reckon a decent 320 engine is going to be quite expensive. Probably easiest to buy a complete car as you'd need so many parts leaving the rest to be sold and recoup some of the outlay. Why not see if a Mazda 6 diesel will mate to the existing RX8 gearbox ? Have you tried a RX8 forum as I'm sure people will already have tried various conversions so will be able to comment on what is needed, what fits, costs etc.
Paul H
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Chop a massive hole out of the bonnet, and slap in a 5.9 Cummins derv ;D
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You're like a crazy backyard genius!
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RobinJI
Posted a lot
"Driven by the irony that only being shackled to the road could ever I be free"
Posts: 2,995
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You may actually be better off using a PD130/150 Passat engine. They're tried and tested swaps into other cars, so the wiring side will be a bit more manageable as there's more info out there on it, and being really quite slanted with a narrow head, they've got more chance of fitting under that nice low bonnet without loosing ground clearance or putting an unsightly bulge/scoop in the bonnet. They're also still very tunable but seem more reliable than the BMW's. The Passat engine's already inline, so the downpipe exits in the right place, the engine mounts are in the usual place for RWD stuff, there's nothing in the way on the back of the head ect...
I do like the idea, but I agree that you'd never get the cost back if paying someone else to do it.
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Last Edit: Feb 10, 2012 2:13:45 GMT by RobinJI
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The Mazda RX8 always reminds me of the Eagle 2.
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Nice idea but probably not feasible to use a BMW engine. The Omega lump is a straight 6 so probably too long. The 320 engine is gutsy but a neigbour had one last year and money pit that he still didn't get sorted as turbo then started to fail. Also I reckon a decent 320 engine is going to be quite expensive. Probably easiest to buy a complete car as you'd need so many parts leaving the rest to be sold and recoup some of the outlay. Why not see if a Mazda 6 diesel will mate to the existing RX8 gearbox ? Have you tried a RX8 forum as I'm sure people will already have tried various conversions so will be able to comment on what is needed, what fits, costs etc. Paul H The 2.0 diesel engine in the 6 is even more unreliable than the 2.0/3.0 BMW diesels!! Otherwise a great idea... ... Not far off is a Duratorq Ford engine. Actual economy, reliability (apart from dual mass clutch) and got to be some family parts that will make it bolt up. The BMW tds engine is great, but the newest of them are approaching 15 years old and mostly with big mileages. The newer BMW diesels are appallingly unreliable and to be avoided at all costs.
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Joe T
Part of things
Posts: 711
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Is there actually room under the bonnet for a regular four-pot? I thought the great packaging of the rx8 was built around its low footprint engine?
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I don't understand why you need to get the costs back? I very rarely meet anyone that breaks even with a modded car, they do it because they love it and in there eyes its viable, hence the 20k MK2 Escorts. I know I'll never get a quarter of the money back I have spent on my 205 or MR2 for that matter but we all carry on doing it
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Some days you just need to take a grinder to an inanimate object, just to make your day a tiny bit better!!
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Id be worried about replacing an engine that designed to rev its nuts off, with a slow running engine. Mainly due to the gearbox being geared for revs, I can imagine an engine that is on redline at 5k being damn slow with the RX8 box on the back of it.
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If, as suggested, some engines are too tall, why not get a Subaru boxer diesel - just disconnect the front wheel drive bit.
(I have no idea how complicated this would be - very, I suspect)
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goldnrust
West Midlands
Minimalist
Posts: 1,880
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Is there actually room under the bonnet for a regular four-pot? I thought the great packaging of the rx8 was built around its low footprint engine? I think this will be one of your biggest problems. I know Mazda kept going on about being able to keep the rx8 bonnet line low because the engine is low. Rotary engines are kinda square, where as a piston engine, especially something like a straight 6, are long, tall and narrow. Also rotaries are light and if you stick a great big diesel lump up front it'll upset the handling no end. Ignoring my personal distaste for diesels, I think you'd be better off buying a car that came out of the factory as a diesel powered sports coupe, like a Sirocco or maybe a Brera or something? Especially if you'd be paying to have the conversion done, rather than doing the work yourself as a hobby.
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nofrills
Posted a lot
my wings are made of Steeeeeeeel!!!
Posts: 1,243
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Feb 10, 2012 10:05:14 GMT
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There is a rx8 with a cossie engine conversion happening at the moment from Martin Hadland or reyland fame, will try and find the link
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Feb 10, 2012 10:20:40 GMT
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You can get a relatively large engine under there - you have to remember manufacturers have to keep the engines well away from the bonnets to meet pedestrian impact regs these days, whereas, well, if they hit the bonnet on your own car, they shouldn't have been in the way.... However, if you look at just how short and low the RX-8 engine is - you can barely see it under the bonnet it's tucked so far back and down - you see why they make a big thing of the packaging as it'll make a big difference to the moment of inertial in yaw with a normal engine hung out the front instead. Personally, if you must do an engine swap, I'd be looking at just bolting the MX5 unit onto the gearbox and giving it some healthy Eaton loving. Wouldn't even bother with a diesel - it's not going to save you much money when you've just spunked 5 grand on the conversion...
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Last Edit: Feb 10, 2012 10:25:11 GMT by phillipm
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Feb 10, 2012 10:34:34 GMT
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Re: my suggestion of using a Subaru diesel unit.
The good news - I think it's short enough top to bottom (20 inches versus just over 20 inches) but the bad news is it's much wider (31.5 inches versus 21.5 inches).
Shame as it's really short front to back and doesn't weigh much.
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Feb 10, 2012 10:37:06 GMT
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plus the ecu would be a bladdy nightmare to sort out being from a pretty new vehicle, canbus curse word etc.
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