How dumb is this idea?

Sitting in the shop hanging from the side of a 3.8 liter Jaguar engine is a brand new 250 cu in Roots supercharger. 

Sure there are three SU carbs  on the intake side but they can be put back on the self.  

My thoughts are to mount that on the V12 going into the MGUAR ( MGTD with Jaguar running gear) I'm building. 

If you turn the intake manifolds around and cut off the ends you can build a plenum chamber that will hold the supercharger. Then on top of the blower put two Holley 4 barrels jetted and set up for s small.block Chevy.  Jaguar is 326 cu. in. Compared to Chevy 350  so the carbs should be close. 

I understand Small block Chevies aren't as powerful as the same year Jaguar ( contrary to popular myth) but richer jets are easily available  

Jaguars come with either 7.8-1  or 11.5-1 compression the low compression has the great   ( think Hemi) heads and the 11.5 has the poor heads (think 40s&50s Chevy fireball six) heads 

I'm tempted to use the high compression heads and use E85 to prevent detonation under  boost

It's an astonishingly, horribly, terribly, obnoxiously, insanely bad idea.  When do you start?  don't forget to document every step of the way for those not as confident as yourself.  

I don't think I understand the question.  An MG TD with a supercharged Shaguar V-12, sounds like an excellent idea, but use pressure treated wood to reinforce the frame, you don't want the rust to rot your wood.

Use the low compression heads.  Less chance of detonation and will probably end up breathing better and making more power.

In reply to Toebra :Well a few body parts of a MGTD will be used but most will be used as a pattern to take molds off of. If you've ever picked up the front subframe of an XKE  you'll realize exactly how light a properly engineered frame can be. I believe I can build the frame under 100 pounds and have it stiff enough to work nicely. 

T series frames weigh far too much and have virtually no stiffness ( ps, unlike Morgan, MG never used wood in it's frame,  while they did use wood, it's purpose was to hold the body rigid enough to open and close doors.). 

As for the idea of low compression with better heads that might be true if not for the use of Alcohol. According  to the computer there is 42 more horsepower going with the higher compression and bad heads  

Frenchy, My Man ... it's not a crazy idea. It's an extremely creative proposal, and I'd love to see it turn into reality. But ... how old did you say you were? And how long would this take? 

Incidentally Frenchy, I want to personally commend you for having the fortitude and stamina to re-invigorate this sleepy CMS forum. Lately, it's been propped up on re-issues of existing magazine and e-magazine articles by management. And we've lost too many former influential members. (Just look at the participation here 5-6 years ago. Much greater then than now. We've lost a lot of good people. I wonder why?). Anyway, we appreciate your effort. You are awesome! Keep up the good work. Those of us who still lurk here really should step up our participation.

PS. I like the bold font in your posts. Nice statement! Or is that just a result of the new software? Anyway, you are developing a following here. I always look for your posts, and your wit and wisdom!

In reply to Gary : my experience tells me that a from scratch race car takes about 2000-2500 hours to achieve ( at least to the level I want)  While  I've done them in less the corners I've cut reflect that. 

I'm well on my way to 70 with most of my spare time still spent working on the house I'm building. However that is rapidly approaching the point where I will be finished and I'll be able to devote real time instead of the odd hour or two I have so far.  My health is  really good and I'm eager to achieve as much living as possible before I take my long dirt nap  

Gary, thank you for your kind words, I've found kindred spirits here who try to achieve automotive fun on a modest budget and share their trials and success with those of us  who lurk here.  

Here are some astonishing people who share themselves and their experiences plus a few smart asps to keep us all humble

In reply to Adrian_Thompson :I've already started, sort of. I jigged  the assembly up to see if it would fit and work. Now all I'm doing is deciding details.  For example I have a perfectly nice turbo 400 transmission that is only a shift kit away from ready. On the other hand I have this really cool racing 5 speed with Dog clutches that makes shifting insanely fast for racing but would make it nearly impossible to street drive. 

My first thought was to hang 6 Strombergs off the fuel injection manifold ( 3 on each side) which should get me a nice 350 horsepower with 385 foot pounds of torque. When I moved my six cylinder around I rediscovered the Roots blower I’d adapted to an old 3.8 liter Jaguar six and realized I'd never considered the effect of one of those on top of the V12 

The computer projected  520 horsepower with 610 ft pds of torque  and that seemed like fun.          

ps so far the computer has been within 2% of actual Dyno horsepower so I'm reasonably confident of the numbers.  

Document including pictures assumes someone helping me to post pictures 

That's not easy for me to do. I need a teenager willing to be patient with Grandpa. 

You will probibly need two of those super chargers. Otherwise a larger single to see any meaningful boost on a v12.

In reply to dean1484 : it came off an earlier 3.8 six cylinder that is every bit as long as the V12. The discharge area nicely covers the area the reversed and modified intake manifolds have their inlet.  

The twin Holley 4 barrels sit right over the same area so I believe fuel distribution will be pretty close to perfect.  Boost is more a function of speed of the blower in relationship to the speed of the motor. 250 cu. in. Per rotation should easily get me about 8 psi with the pulley ratio I have on hand. And if I want I should be able to easily approach 20 psi before pumping losses cause excessive heat that won't be taken care of by the use of E85 

My only real concern is the stock camshafts won't open the valves long enough or wide enough to use all the pressure the supercharger can put out.  

Hmmmm....V12 in the nose of a MGTD......and all of this within the confines of the 'bonnet'?  Kant wait....from a lurkin asps. You're an inspiration to us young (64) pups!!!!

Well,... we sorta

Fchyd.....if you can keep the louvers on the bonnet kinda intact 'round the v12' you're my hero...

In reply to 759NRNG : I'm not sure I want to but yes a full bonnet including sides would cover the V12 

The humor of that massive V12 where the tiny little 4 cylinder was is just too rich to resist.  

By the way the hood on a T series is 43 inches long. But the engine is only 19 inches long.  The rest is legs, toolbox, and battery.  

A V 12 can be as short as 31 inches which if the rear of the block is at the cowl leaves a foot before the radiator  

It is not the size it is the displacement.  What is the displacement of the V12 compared to the motor that the unit is coming off of? 

In reply to dean1484 : the supercharger displaces 250 cu in per revolution. They are typically used on hot rods with displacement from 350 cu in to 454 cu in. Imagine a 671 supercharger  that is just as long but about 2/3 as tall.  

I had it made for a 3.8 liter Jaguar six cylinder and did the adapting myself. It only added 36 pounds to the engine and since it's massively oversized I could underdrive it. Because it's a Roots type I didn't have to worry about lag or anything. 

You are thinking of putting the blower on a v12 yes?  What is the displacement of the v12?  A blower that works on a 3.7 l 6 will have to be over spun quit a bit to work on a 6l v12. At some point you run in to efficiency issues. Usually somewhere between 12 an 18 thousand rpms. Depending on the design. 

I am not saying it will not Work. I am just wanting to know the displacement of the v12 so I can plug-in the numbers to see the performance potential. If you had the crank pully and the blower pully diameters that would be the last bit of info I need. I have a spreadsheet that will tell you alot about the combination and let you make tweaks to things to optimize performance.  It can also give you estimated hp and torque.  

In reply to dean1484 : would it help if I told you the original application was for  350-450 cu in engines?  

I used it because it weighed only 4 pounds more than the 175 cu in blower they offered and by under driving it the charge would be cooler  I was vintage racing and the class I was in was dominated by 500-650 horsepower Chevy small blocks.  My computer told me that was possible depending on how fast I spun it and what fuel I used.  I use Performance Trends  program since every engine I've built since I got it has been within 2% of actual Dyno numbers  Granted I need actual flow numbers from a properly calibrated flow bench etc.  but even my homemade shop vac flow bench gets me in the ballpark.   

  Jaguar's  V12 is either 5.3 or 6.0 liters ( 326-366 cu in)   And can easily be taken out to 7-8.4 liters.  

As for pulley sizes, which set?  Underdriven or over driven? Plus they still make them so different is a phone call away.  

I still have dreams of a V-12 in my Cobra Chassis  It's an E R A built but the body was destroyed in a Carb Fire on the 427. 

If you have the stamina, go for it.   My minds eye pictures a Supermarine Spitfire.

Build it!!!  You could make a torque monster!!!!! 

In reply to Dirtydog :there is actually a scale model Spitfire in England powered by a Jaguar V12 engine was taken out to over 9  liters

I guess it was cheaper than a Merlin.   9 liters must be near maxed out.

In reply to Dirtydog :Well they cheated and used deck extensions.   Not only a ton cheaper but believe it or not a thousand times more reliable.  

At the end of WW2 Rolls Royce went looking for the Merlin engine that had run the most reliably through the war. 

No engine had ever gone over 120 hours!!!! 

That's right  the engine that won WW2 never got more than 120 hours!!!