A V6 seems the best compromise regarding engine set back, weight, power, etc. The Ford 3.0L duratech with Contour 2.5L SVT heads will make over 220 HP without much work past bolting it together.
A V6 seems the best compromise regarding engine set back, weight, power, etc. The Ford 3.0L duratech with Contour 2.5L SVT heads will make over 220 HP without much work past bolting it together.
In reply to dherr :
I checked out your Spitfire project. Neat project. In my case, keeping the GT6 rear suspension, but with CV axles seems like a really good way to go. I hadn't thought of that.
Another question for folks with GT6 experience: That GT6 front steering with the backwards Ackerman angle is famously unpredictable under hard cornering, so I've been told. I have access to a Spitfire parts car, including the entire steering and front suspension. Would it be feasible to swap the Spitfire steering to the GT6, putting it in the proper location farther back in the car, provided, of course that the engine swap cleared enough space?
In reply to Torqued :
The GT6 and Spitfire front suspension are geometrically virtually identical. The GT6 parts are somewhat more robust.
After nearly 50 years owning and racing and building these cars, I've NEVER had, or heard of the issues you describe.
I can attest that under hard cornering, the front suspension sticks like crazy.
The several SCCA National Championships also attest to it's capability.
In fact, anti-ackerman steering can be taken advantage of, if you are clever.
The issues with these cars almost always comes down to the REAR suspension not being as capable as the front.
Someone has been feeding you a load of hogwash.
In reply to clshore :
I'd agree. It's really one of those issues that only presents itself when the steering is at extreme angles rarely seen and never at any sort of speed. If anything, it could use a bit more negative camber, but that is easy to take care of with aftermarket upper control arms.
The spindles and brakes of the GT6 are slightly beefier and not difficult to swap over, which is a project I plan to do on my Spitfire (with parts I bought from Jensenman/Curmudgeon prior to his passing. 
). I also plan to swap over to the GT6 Rotoflex rear as well (with CV axles) and GT6 rear brakes. But in all honesty, it's just as much so I can stock one set of brake parts as for any perceived performance improvement - since I have a '72 GT6 as well.
The original thread started in 2010.
Nowdays, I'd be looking at a Honda L15 swap (!!!)
Yes, it's a 4 banger, and 'only' 1.5L.
But it's light, it's VERY compact, and it's ubiquitous ... Honda has manufactured millions of these motors.
No need for complicated re-engineering to set it back, it's lighter than a GT6, lighter even then a Spitfire, and COG is already rearwards.
The chassis crossmember will need to be modified/relocated, as the L15 has a full length oil sump. But that's minor work.
In OEM factory NA form, you can get up to 130 HP.
In OEM factory Turbo form, you can get up to 230 HP.
Honda has specified a turbo L15 version as the base motor for all 2018 Honda Accord cars.
It produces 192 HP, and features a flat 192 ft-lb torque curve from 1500 to 5500 RPM.
Those are factory figures for the USDM, and Honda robustness and reliability is a given.
There is however the significant issue of a suitable RWD transmission, and no currently available bellhousing adaptor.
The best candidate I've seen is a BMW 3 series, either ZF or Getrag.
These have integral bellhousings, so a ring style adaptor could be employed.
But they are compact, robust, available, and the starter locations are close to lining up.
That said, I'm going a different way, at least for now, but I see this as the future of Spitfire/GT6 swaps.
Does the L15 have the issue of being reverse rotation? I seem to remember that being an issue with some RWD conversions using Honda engines, although the limited info I've found through Google says these are B, D & H series.
In reply to Ian F :
Yeah, Honda went to a conventional rotation around this civic.
As far as I can tell, the Fits and Accords, etc all did so around the same time. The above Civics had slightly oval pistons, I believe.
Rip mike.
Fueled by Caffeine said:Rip mike.
Yeah, RIP, guy.
What transmission would bolt to the Suzuki in that application?
Im not sure how far along Curmudgeon got, but I sent him a gas pedal for a Spitfire just a few weeks before he passed, so he was still at it.
ignorant said:v6spitfire wrote: Another idea - use a Buick V6. There is enough room in the engine bay and the deck height of the Buick blocks is lower. Stage II Buick parts are found fairly easily on e-bay. 400Hp is not a unrelaistic number to achieve for a properly built naturally aspirated deal.I like this. The 231 is a GREAT engine.
Go with a turbo on it and you could have a gt6 grand national or gnx and would probably be an interesting very fast car.
another option for something different if u can find one would be one of the old SOHC pontiac sprint straight 6s. This would allow the car to still have a straight 6. Back in the day car and driver put one of these engines into an xke. Now this is would be neat also since the gt6 was conceived as a poor mans xke. Not sure about packaging though.
In reply to MotorsportsGordon :
Packaging for any OHC 6 will be difficult in a GT6. The bonnet barely clears the stock OHV engine.
I recently saw pictures of a Buick V6 in a Spitfire. Looks reasonably clean.
Now if you really want a project with work and fabrication and keeping it British may I suggest v12.
Think small and lightweight.... a big domestic straight 6 would be heavy and affect the handling even worse than the GT6’s weight up front did. Internet says between 450 and 550 pounds for the OHC version . Best engine is a small modern 4 cylinder, turbo it and you will have all the power you need. A Honda engine would be great, but the easy option is expensive (S2000), other options like a K series means using an adapter and finding a transmission. For me, best option is a JDM engine and transmission for RWD and making the rest of the mods. I went Miata but plenty of Toyota, Mitsubishi, Nissan and Mazda options....
In reply to MotorsportsGordon :
Have you actually measured one of those (assuming you could even FIND one).
The front pulley would wind up somewhere forward of thr bumper
Old post but just ran into this one of a kind. Very wide fender flares, Chevy 3.6 l 4 bbl carb, made to Bill "Grumpy" Jenkins spec's using a corvette cam grind, custom headers, 10.5 comp. 330 hp to wheels. 
Ian F said:In reply to MotorsportsGordon :
Packaging for any OHC 6 will be difficult in a GT6. The bonnet barely clears the stock OHV engine.
True. I think a previous owner of the GT6 I owned in the early '80s learned the hard way, that putting the upper radiator hose hose-clamp on crocked makes a dent in the bonnet.
Wow, hard to believe this thread is 12 years old. There's a lot of good discussion here. I've got a 71 GT6, and I have been pondering what motor would be the best choice since this thread began. I love the sound of the triumph motor, but it is a boat anchor, and it is also becoming more and more expensive to tune and maintain.
From an old school perspective, I have heard of a couple of people who have installed Ford Kent motors, but parts for those are also becoming a bit more scarce/expensive. I don't know how hard the Miata motor swap might be, but that sure sounds like it could be the path of least resistance and, perhaps, the all around best choice.
-chris r.
I am putting the engine behind the driver for my GT6 build and it will be something you probably have never seen before, so I can't tell you.
It will have the RX8 suspension. This is how I got it, was missing a few parts..but I got them for $150, $30 for the engine, and $50 for the trans,
and $150 for the RX8.
Look at Ecoboost or Ecotec 4 cylinder engines. Reasonably small and huge power possibilities. But you sure want a later GT6 to eliminate having to deal with handling foibles.
One outside engine choice that I would love to see (but then I'm weird - or so my wife says) is the Mazda K series small V6 (up to 2.5 l) that can put out tons of power at dizzying rpm. And they look absolutely great! Here is one bank.....
wspohn said:Look at Ecoboost or Ecotec 4 cylinder engines. Reasonably small and huge power possibilities. But you sure want a later GT6 to eliminate having to deal with handling foibles.
One outside engine choice that I would love to see (but then I'm weird - or so my wife says) is the Mazda K series small V6 (up to 2.5 l) that can put out tons of power at dizzying rpm. And they look absolutely great! Here is one bank.....
What longitudinal transmission fits that Mazda K?
I've suggested the Honda L15, compact, lighter than a Spitfire motor, far lighter than a GT6 motor, rugged, widely available, and cheap.
Stock versions from up to 130 HP NA in the Fit, to 200+ HP turbo in the Civic Sport.
But recently, I've been doing some research, and it opened my eyes to the possibilities.
Folks are making reliable 360+ HP to the wheels, using stock internals, with bolt on turbo kits, and piggyback ECU.
stroker said:wspohn said:Look at Ecoboost or Ecotec 4 cylinder engines. Reasonably small and huge power possibilities. But you sure want a later GT6 to eliminate having to deal with handling foibles.
One outside engine choice that I would love to see (but then I'm weird - or so my wife says) is the Mazda K series small V6 (up to 2.5 l) that can put out tons of power at dizzying rpm. And they look absolutely great! Here is one bank.....
What longitudinal transmission fits that Mazda K?
See this thread https://grassrootsmotorsports.com/forum/grm/mazda-k-series-with-rwd/151175/page1/
And watch this!
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