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Message |
    
Mark Tomlinson
Frequent User
Username: mark_tomlinson
Post Number: 15
Registered: 9-2003
| | Posted on Sunday, 07 March, 2004 - 18:19: |    |
I have recently purchased SRH 11776 a 6.75 Litre 1971 shadow stretched in 1988 and was wondering if the Bentley turbo chargers will fit this engine? Being such a rare car anyway I was looking to make it even more so by adding some more RR built power to push the extra weight around. |
David Gore
Moderator
Username: david_gore
Post Number: 221
Registered: 4-2003
| | Posted on Sunday, 07 March, 2004 - 18:50: | |
Mark,
Good idea but will need a lot of work to get right - I would source a late-model turbo engine complete with EFI and engine management system/sensors to replace the current engine rather than trying to turbo the existing engine and facing the problems of getting the boost pressure and carburettor settings right.
Dare I suggest it might be more economic to talk to Robert Chapman about installing a "worked" GM engine to meet your power needs whilst you own the car and keeping the original engine intact for re-installation should you wish to sell the car in the future. |
Robert Chapman
Prolific User
Username: shadow
Post Number: 39
Registered: 5-2003
| | Posted on Monday, 08 March, 2004 - 20:56: | |
Hi Mark,
I think David is right,sounds like a good idea but would take a lot of work and time off the road.As I know this is a working car I dont think that would suit you.From an engineering point of view I dont believe a Shadow can take a lot more power without serious modifications to the brakes and especially the rear end.
Besides you have the Harley for when you want to burn rubber.
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Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 134
Registered: 4-2003
| | Posted on Monday, 08 March, 2004 - 21:35: | |
As Robert hints, it was no accident that the Mulsanne Turbo was introduced with bespoke beefing up of the drivetrain.
It all strongly suggests that the SZ, and presumably also the Shadow, drivetrain was near its reasonable limit with the standard motors, otherwise Crewe would not have spent a fortune uprating it just for the Mulsanne Turbo. Remember, the Mulsanne Turbo was partly an experiment for Crewe. It was not expected to sell in large numbers at first. Its relative runaway success, and especially that of the later Turbos expecially, stunned Crewe. If the Normally Aspirated (NA) setup could cope, I would have expected early turbos to have been introducesd with standard drivetrains to test the market before investing heavily. Thank goodness they did upgrade it from the start and so cement the reputation of these cars' reliability.
To start, Turbo cars had the normally aspirated cars' Woodruff-keyed driveshafts replaced by much more substantial splined ones. The normally aspirated cars kept on with keyed shafts for some time. The Turbos had also beefed up CV joints compared to the smaller ones on mid-range NA cars and the Detroit joints on early SZs and on all Shadows. Also, the SZ cars had a more substantial diff carrier torque arm (a weakness on Shadows, and most failed on early Shadows). The Turbos also had taller back axles: Shadows and normally aspirated SZs were 3.08:1, Turbos were 2.69:1 and 2.28:1 from 20,000 series onwards until the 4 speed transmission was introduced in 1992. Also, there were universal joints on the propshaft (note the same as a Shadow, reverted to on all SZs after 30,000) in place of the rubber coupling.
A Turbo motor may just rip out a Shadow rear end in all these areas due to the massive torque, and the gearing would not be ideal.
All in all, it would be a very expensive and time intensive exercise not guaranteed to be straightforward nor necessarily legal. With an ECU for the turbo, one for the ignition and one for the EFI if fitted, the electrical work alone would be massive even if parts of an SZ looming and its auxilliary devices can be largely salvaged. |
Mark Tomlinson
Frequent User
Username: mark_tomlinson
Post Number: 16
Registered: 9-2003
| | Posted on Monday, 08 March, 2004 - 22:07: | |
Apart from frightening the living daylights out of me Richard, you have convinced me that she goes very nicely as is.
As for changing motors,,, BAHHUMBUG!!!NEVER! |
John Dare
Unregistered guest
Posted From: 144.138.194.210
| | Posted on Tuesday, 09 March, 2004 - 07:49: | |
Mark, Having just caught up with this matter I see you have received ample advice both sound and balanced. You original concern seemed to be that perhaps you needed more power to move the extra weight resulting from your "stretch" conversion etc. I have driven a Shadow which had been "armoured" from new with 1 inch thick fixed windows/glass (to resist 7.62 mm) and reinforced floor for anti grenade etc., similar to cars which were supplied to NATO in Brussels and assorted foreign dignatories etc. I felt that the performance of that car was only marginally down, given the extra weight occasioned by the modifications, so I imagine your own car should cope with the additional burden of the stretch conversion in normal driving/operational conditions. A friend of mine here in the ACT purchased some years ago, a "Pontiac" which had been built for the then U.S Ambassador, Washington presumably telling GM, "Build THIS"! That car was fully armoured with a highy modified engine which would have enabled it to move very quickly in the event of an incident but for normal driving it was no doubt overpowered. I suspect the Embassy didnt have to worry about the fuel bill though, 6 mpg if you were careful!. |
Mark Tomlinson
Frequent User
Username: mark_tomlinson
Post Number: 17
Registered: 9-2003
| | Posted on Tuesday, 09 March, 2004 - 08:19: | |
I have never owned a V8 prior to the two Rolls in the last 9 months but have owned a few high performance bikes, the current and last one (wifes orders) a highly modified Harley.
When no passengers the Rolls is very impressive as far as performance is concerned, When you get three men and two women in the back it has the power to weight ratio of a skate board.
I was looking at it more from a moving exceleration point than a standing start exceleration if you get my drift. |
William H. Trovinger II
Prolific User
Username: bill_trovinger
Post Number: 80
Registered: 8-2003
| | Posted on Tuesday, 09 March, 2004 - 09:26: | |
Mark;
Back in the late 70’s and early 8o’s there was a company here (in Milwaukee) that stretched first Shadows and later Spurs. I did some financing for them and one of the livery companies that leased two of his cars. I do not remember any complaints about the cars being underpowered and as I recall they did little or nothing to increase the performance of the engines. I do believe that there was a gearing change made. However, I do not remember if it was to the GM transmission or to the rear end. The real problem they had was the added weight was too much for the rear suspension even with larger springs and shocks, the cars would “bottom out” if more than two or three people and luggage where in rear. They had real fun adjusting to get the rear beefed up enough without destroying the car’s ride when only one or two people where in the rear.
John;
Just for your information US government does not have GM armor their diplomatic cars. This was done up till 90’s exclusively by Hess out of Indiana and is put out for bid to several different companies now. Hess has been doing this for the government since the second armored Presidential limousine. The first of course the president got second hand when the IRS confiscated Al Capone’s armored limousine.
Regards,
Bill
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William H. Trovinger II
Prolific User
Username: bill_trovinger
Post Number: 81
Registered: 8-2003
| | Posted on Tuesday, 09 March, 2004 - 15:08: | |
John;
Sorry Hess is not in Indiana but Ohio and is now part of Armor Holdings, Inc. Oh, the first Presidential Limousine they built was from Harry S. Truman. And yes, they did build the car that JFK was riding in that day in Dallas.
Regards,
Bill |
John Dare
Unregistered guest
Posted From: 144.138.194.198
| | Posted on Tuesday, 09 March, 2004 - 17:40: | |
Bill, Thank you for your advice that certain official U.S Govt cars are "armoured" by the private sector rather than the actual car mnfrs. as loosely implied by my earlier post. I stand corrected but ever mindful that one must be careful when delivering statements as if they were "facts" carved in stone from ahigh. That is why I prefaced my casual assertion re Washington/GM etc. (intended to be illustrative) with the all important word "PRESUMABLY" as I was uncertain of the true situation which you have now clarified. |
William H. Trovinger II
Prolific User
Username: bill_trovinger
Post Number: 82
Registered: 8-2003
| | Posted on Tuesday, 09 March, 2004 - 18:14: | |
John;
No problem, these are two areas of interest for me (US Political History and cars) to be honest most Americans if asked would think that the manufactures build the cars for the government. Part of the confusion is for many years starting with JFK’s limousine the Secret Service ordered the cars from Hess & Eisenhart but Ford Motor Company purchased the cars and then leased them back to the Secret Service at a lease rate of $1.00 per year. Ford felt that it helped Lincoln’s image. Government later had the same deal with GM for Cadillac limousines. It caused a rather humorous situation when Congress (who often acts without thinking) decided to cut government spending by getting rid of all the limousines for officials lower than cabinet level. So the government went and purchased regular old sedans (Buick, Ford and so on) of course neither GM nor Ford saw any PR for them in these cars so they charged normal fleet prices. In the end the government spent more per year on an Impala Sedan to run an under-secretary around in then the limousines had cost.
Best regards,
Bill
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