turbo sprint engine

[Carledo]

With the emergence of systems like the near DIY Megasquirt and its fellows, I reckon Clive is onto a winner. Webers are expensive, thirsty and need extensive rolling road time with an expert to get "just so"
EFI is more efficient in every respect and, once fitted, can be programmed by the owner with a laptop. Normally, just fitting it will give a small increase in performance and a somewhat larger boost to fuel economy.
My Toledo, running only stock Vauxhall efi (remapping soon) produces around 130bhp from a 1998 cc SOHC 8V 4 cylinder lump. Nothing startling you say, that is very close to a standard Sprint output - and you'd be right, though the Sprint lump really should be better, with its 16 valve layout. The big difference is I thrash the daylights out of my Vauxhall lump and it not only comes back for more, it is AVERAGING 36mpg doing it! A well sorted stock Sprint, used the same way will not only not last long, it will struggle to manage 25mpg. Which, in this day and age, is expensive folly!
Even when i've done the remap (about £200) I don't expect the average fuel consumption to be materially affected since the remap will concentrate on the area above 4500 rpm and once it has been done, I can make any further adjustments myself, through use of a programmable chip. Then there is the other upside of EFI, it doesn't need to be frequently retuned to keep it at the top of it's game, you just fire it up and drive away, year after year if need be!

Steve

[Carledo]

to get 200bhp from a sprint engine would not exactly be a budget build. I am guessing 3K+

Not that I accept that estimate, but the costs of having a none standard engine, and presumably gearbox, propshaft, and exhaust system, fitted at £40 an hour or so must be fairly high, surely - even if you get the engine for nowt.

Graham

Once again, Clive has the right of it here, anyone contemplating such a swap would not be PAYING someone else to do it. Half the enjoyment is gained from the experience. That's why, lovely as it it is, I would not contemplate buying MBs old Redtop Toledo, my own effort is not as quick and not as pretty (nor was it anywhere near as costly) but it's MINE! I can look at that car and think "I did that" and, to me, that's worth a lot! It's why the only way it will be sold is by my executors!
Not that it's important, but as it happens, I did get my current engine for nowt, however a running replacement would not cost much more than £100 from a scrappy, I already have 1 and a half spare engines put by for a rainy day. But I don't expect to need them, not many Sprint owners can say that!

Steve

[GrahamFountain]

I can only say that at 190 hp or so, and in a TR7, the only non standard bits were the big end bolts, the cam, the inlet and exhaust manifolds, and the carbs (and an electric fuel pump). And the stronger big end bolts were only there to increase the safety margin on over-revving the engine, not to take the extra forces at 190 bhp, or whatever.

It's true the engine had already been professionally re-built by a proper motorsport company around Mahle pistons, quality bearings and seals, etc., and properly balanced and blueprinted, etc. (I only did the simple stuff with the body shell, prep for paint, and installed the interior, etc.) Thinking about it, IIRC it also had the Kent cam before the 45s. But with one very disappointing exception when the factory TR7 Sprint's engine went away to Lincoln to be reconditioned that's the only way I've had engines rebuilt - even to run on HS6s, and not especially to take the 45s. So, presuming an engine's been built properly, it should take that level of upgrade in its stride.

But, on SUs, it was still a bit flat – and I was having intermittent problems that turned out to be caused by the locking petrol cap letting in water and rusting the fuel system. So, after a year or so, I decided to try a pair of side-draught carbs. And I can only describe the change as startling. I let a mate drive it back to York from Southport (A59 route via Preston and Harrogate), when we went to pick-up the Yellow V8 I'd bought off a Mr Onions. He (the mate) would only describe the Sprint thereafter as the "Psycho-killer car". I thought it was just loads of fun, and I know its acceleration gave the owners of several tuned V8 TR8 a shock. Which just goes to prove that a simple comparison of horsepower's doesn't tell you the whole story, and where peak power happens in the rev range, which is determined by the shape of the torque curve, matters too (power = torque times rpm times a constant frig factor).

So, the only costs I had in going from something like 150-160 at the flywheel to something like 190, and a real character change in the car as well, was in the carbs, inlet manifold, and fuel pump. That lot cost about four hundred pounds in the mid 1990s, a few hours of my effort, and was a fairly easy job, even by my tyro's standards. Don't know what that would be now, but it ain't 3k (unless we're now part of the Weimar Republic, and I missed it – anybody got a spare wheelbarrow, it's nearly payday).

And I emphasize the character change in the car, because going from 160 to 190 hp isn't actually very much, when you consider that top speed goes roughly with the cube root of power – so a 20 percent increase in power only gives something like a 6 or 8 percent higher top speed.

It didn't make the car much thirstier, when driven in the same way. I kept an eye on the fuel consumption when I used it for work, and it stayed about the same 10 gal a week - 25-27 mpg - before and after the change to the 45s. The carbs were Dellortos not Webbers, but I don't think that's significant. It did need setting up on Mr Bogg's rolling road, once to see what needed changing in the jets and once more to see it was right - which cost £50 a time, as I remember. But thereafter, it didn't seem to need any more work.

On the subject of reliability, that engine was still going really strong about 3 or 4 years later, and I guess 30 to 40 thousand miles or so (I was doing a lot of miles, but I had the V8, when the wife let me, and the real TR7 Sprint, when the rot let the axle stay connected to the back of the tub). As I remember A TR7 16V the second went to several TR Register and TR Drivers weekends, and to the North Yorks and Lake District weekends, etc., a couple of times over the years; both on SUs and 45s.

It only died because I got rear-ended by a Discovery, and while it was waiting to be scrapped, some bar steward broke in the yard, stole the carbs and manifold, and left the engine to fill with rain water. And as I'd been paid out on the car as a write-off and for the whiplash, I wasn't bothered enough – I regret that now though.

I admit that my experiences only apply to a 190 hp (approx) engine in a TR7 Sprint. So there could be a bit more to be done, e.g. on the cooling, to sustain 190 hp in a doly's engine bay. But if that's true with the Sprint engine, it's probably true with any 190 hp engine of whatever ilk. And I don't know about the limitations of the exhaust manifold, but I think that only means 5 or 10 hp less than you'd get in a TR7 with a tube manifold, or a bit less efficiency, if you can cam and jet, etc., to the same hp. I've have had well built, blueprinted Sprint engines on SUs in TR7s and on several different tube manifolds and on a Sprint one. And while there's some difference, I don't think it's huge – and nothing in comparison to the difference a pair of 45s make.

If you can do your own, or want to pay for an, injection set-up, I imagine that will be even better. But changing to side-draughts is almost trivial - even I could do it. If you want to swap to a different engine type, that's also your prerogative. But I think it's insensitive to the nature of the car. And I think it's my prerogative to think that too - and I do just like the engine; if I wanted a Ford or GM engine, I could just drive a Ford or a GM.

Graham

[cliftyhanger]

Indeed.
But have you seen how much a pair of 45's cost these days? And they are often in need of a rebuild.

I remember 20 years ago visiting an early Triumph spares day, and later not regretting buying a set of trople webers cw manifolds for a GT6. The asking price, including filters etc was £100. Today people ask about £1000!
Some "goodies" for all these cars has shot up in price, as some (a few) people are prepared to pay for quality. And of course, some parts are getting very rare. Again, I remember buying sprint heads at £10 a pop. And I sold a mint wing and interior for £40.
Ah, the good old days.....

[Carledo]

I used to run a lot of mkII and mkIII Ford Zodiacs and at various points had 2 Raymond Mays 12 port cylinder heads. IIRC one cost me £150 and the other £200. Both were complete and useable when purchased. One of these heads now is around £5K and at that price will probably need work. Tuning goodies for really old cars are stupidly expensive and hard to source these days whereas last gen tech is usually cheap - the Courtenaysport head for the Carledo only cost me £40 + an £18 skim

I guess Graham and I will just have to agree to differ about the relative merits of our approaches to improving our cars!

I can't help thinking though, that £3K to build a 180ish hp Sprint lump is something of an underestimate, with forged pistons at £900 a set and 2 Webers plus manifold around a grand, then machining, balancing, tuftriding, proper oil pump head improvements, cam, etc etc........ ISTR Alun saying the Quicksprint engine being circa £5K and wrecked at low mileage by a duff timing chain tensioner! Not very encouraging!

Steve

[Toledo Man]

I'm suprised that nobody's mentioned this. What about the Saab 900 turbo engine? This was derived from the slant-4 that was used in the Saab 99 which was pretty much the same as the 1850/TR7 lump? Could it be done?

[tony g]

Pretty sure the saab lump evolved so much that it doesnt resemble the triump any more. Gearbox underneath the crankcase now?

Tony

[GrahamFountain]

Again, I don't accept your estimates for either a pair of new Webber 45 DCOE 152s (£577 inc) or a set of 4 forged pistons (£654 inc), or that you can't get serviceable SH carbs at a reasonable price – though I accept that fleaBay may be a bad place to start. I'd look for Dellortos anyway.

But the point is that you're trying (at least) to estimate costs for one specific situation: in effect – for someone starting with a Sprint with an engine that's either dead or not capable of taking the 45s without dying, and who is able to do the engineering for a full engine transplant. And if you're in that one specific situation, then looking at an alternative type motor might make sense. But I contend that if you're in any other situation, or even if you are in that one specific situation but appreciate the car and its engine for what they are, then it doesn't make any sense at all.

Whereas, if the engine's already been built reasonably (as I consider it), a pair of 45s, with or without a cam, is an easy and comparatively cheap option – considering what paying a garage to do an engine "transplant" would cost – that might get you up close to 200 hp or so (though I make no claims for a doly). They will certainly transform the engine quite remarkably. And I'd argue it's a viable option in a lot more than a single, specific situation that applies to only a very few owners.

On the other hand, it is true that those side-draught carbs might kill or hasten the end of a worn out lump. But like they say, "Only the rocks live forever". And it wanted reconditioning anyway, didn't it?

Graham

[GrahamFountain]

I'm suprised that nobody's mentioned this. What about the Saab 900 turbo engine? This was derived from the slant-4 that was used in the Saab 99 which was pretty much the same as the 1850/TR7 lump? Could it be done?

There's a mention on p1 of this thread and a link to a blown Sprint engined Spitfire. But is it the turbo manifold you're wondering about? If so, I'd be surprised there's one that will fit the Sprint - though the 1850/TR7 might be more lucky.

But assuming there's a manifold, I've seen SU carbed cars turbocharged. You just have to remember to pressurize the float chamber, etc., as well as the induction side - or it blows all the fuel out the carb overflow when it boosts.

Graham

[Carledo]

The engine in a Saab 99 is arse about face and the gearbox is underneath but I have owned one AND had the engine out and it is remarkably similar visually to a TR7 unit except for having a belt driven water pump - no bad thing really! I have noted elsewhere that the 2 models share a timing chain tensioner and probably other parts as well. I would not be surprised if a Dolomite sump and Sprint backplate and flywheel would bolt on. The early Saab turbo also has a very Sprint-like block hugging exhaust manifold, but that is where the good news ends cos in a Sprint, the turbo itself would be plumb on the back of it, sharing space with the bulkhead/chassis/heater motor etc. I have a specialist Saab breaker near me if anyone wants to give it a go........

Steve

[Carledo]

Again, I don't accept your estimates for either a pair of new Webber 45 DCOE 152s (£577 inc) or a set of 4 forged pistons (£654 inc), or that you can't get serviceable SH carbs at a reasonable price – though I accept that fleaBay may be a bad place to start. I'd look for Dellortos anyway.

But the point is that you're trying (at least) to estimate costs for one specific situation: in effect – for someone starting with a Sprint with an engine that's either dead or not capable of taking the 45s without dying, and who is able to do the engineering for a full engine transplant. And if you're in that one specific situation, then looking at an alternative type motor might make sense. But I contend that if you're in any other situation, or even if you are in that one specific situation but appreciate the car and its engine for what they are, then it doesn't make any sense at all.

Whereas, if the engine's already been built reasonably (as I consider it), a pair of 45s, with or without a cam, is an easy and comparatively cheap option – considering what paying a garage to do an engine "transplant" would cost – that might get you up close to 200 hp or so (though I make no claims for a doly). They will certainly transform the engine quite remarkably. And I'd argue it's a viable option in a lot more than a single, specific situation that applies to only a very few owners.

On the other hand, it is true that those side-draught carbs might kill or hasten the end of a worn out lump. But like they say, "Only the rocks live forever". And it wanted reconditioning anyway, didn't it?

Graham

I've not personally researched the price of bits to rebuild a Sprint engine recently but my estimate is based on buying a cheap or average Sprint to use as a fast road/trackday car. In such a case I would rebuild the engine COMPLETELY to start with, so I wouldn't be worrying over which bit would fall off/go bang next, especially if I was looking for more than 150BHP. Having an engine that has already "been built reasonably" would probably be enough to put the car out of my price range at the outset! Even assuming I do all the rebuilding work myself (as if i'd let anyone else do it) the parts and machining costs are going to be steep. By the same token, I would not and have not paid a garage to do my transplant - it's all my own work, for better or worse. To be fair, I have got relatively more "bang" for my lack of buck since I only had an asthmatic 61bhp 1300 to improve on, but I bought the car, did the transplant and some MOT repairs and had the car MOT'd and on the road for a shade under £600. It wasn't FINISHED (are they ever) and getting it to the state it is now has cost an estimated £2k more but the vast bulk of that was body and paintwork which doesn't really count since any Dolomite is likely to need similar treatment!
I could have saved myself a large amount of time and effort by putting Sprint running gear in the Toledo and got a very similar result in terms of horsepower. But I very much doubt that I could have even bought a useable Sprint engine, let alone the overdive gearbox and other needed bits for what my transplant cost me. Factor in the relative reliability of the 2 powerplants as well and for me it's a no-brainer!

Steve

[Norwegian sprint]

Putting the turbo under the car?