Best route for 300bhp+

[alan atkinson]

A slightly OT Thread-jack.

Anyone ever put an IRS back end in an 8?

Better or worse?

[alanprice]

A fair point if I went OT, I apologise if Paul was looking for helpful info and didn't need negative comments.

 

So I will try again, more to the point. If I thought it was possible to get over 300bhp AND be road-useable AND be reliable, I would be happy to pass on my experience and tips. But I believe based on 20 years experience and several engines, both road and race-based, that it is simply NOT POSSIBLE; just about 300bhp is possible, together with a mountain of gearbox and axle-busting torque, from a 5.2 litre. TVR 390? I believe they actually put out 220, the 450 around 260. A good standard Vitesse engine was known to put out 160. The Tuscan 450 put out around 350-370, but only lasted a few races, mainly due to a self-destruct compression ratio (over 13:1, requiring full race 100+ octane fuel). 330rwbhp from a 4.6? That's over 400 bhp at the flywheel and has never been achieved in a full-race spec engine.

 

Nitrous oxide or super-turbocharging would probably give the power, so putting my personal thoughts on the above aside, that might be the best route to go. Or talk to JE or another V8 builder of repute.

 

OT thread-jack? What's an IRS got to do with the engine?

 

But Paul, LOL we won't be allowed to have that sort of naughty fun for much longer, if you get what you're looking for and can honestly believe the claimed figures and the engine lasts, let us know because it will be a new one on me. If you were looking for 230-250bhp, I could be a lot more forthcoming

 

Alan

[alanprice]

Nearly forgot.... you could try Wildcat Engineering in deepest Wales, they claim to have overcome the poor air flow of the standard head design, which is THE limiting factor on the Rover V8, with a completely new design.

 

I recall JE telling me that Wildcat work to very high standards and that he had collaborated on their head design, with a view to taking it up as the next step forward for improving the V8. However he pronounced himself disappointed with marginal results, at great comparative expense to other improvements and which abandoned the use of well-proven and easily-available components.

 

That's it - phew!

 

Alan

[alan atkinson]

A fair point if I went OT, I apologise if Paul was looking for helpful info and didn't need negative comments.

 

 

I actually meant my question was an OT thread jack. It was a passing thought that didn't seem totally out of left field given the comments previously about suspension changes required.

[alanprice]

So much for keeping quiet I can't help myself, but I need to apologise to Alan from the US for getting hold of the wrong end of the stick.

 

I've probably been on too much of a downer on this subject. Lots of lovely V8 power with just the right soundtrack, is a glorious thing to enjoy! It's just that Paul was looking for a set of parameters including 4.6ltr and bolt-on bits and I remain convinced that 300+bhp just ain't available. RPi Engineering advertise their 5.2ltr engine at 350-380bhp, but it's absolutely top-spec and built by them and costs £6500, then you've got ancillaries like bigger radiator and exhaust and oil cooler and fuel pumps to cope (surely?) etc etc, then VAT, it must all come to the thick end of £10k.

 

I suggest settling for "adequate" power (i.e. exhilerating), don't get hung up on bhp figures and build or have built an engine where the components match. For my own race engine, I know that another 50bhp is available with heavily worked heads and crossover throttle-bodies, but that's another £5k+ and believe me, straight-line speed is not the problem on UK circuits! Increasing the capacity will only really increase the torque and I don't want that. I'm more satisfied with an engine that is conservative-spec, running on pump super-unleaded, is very driveable and holds together, partly by getting rid of troublesome parts like the dizzy and oil-pump drive and running cleanly on programmed EFI and multi-coil ignition. Even so I expect my beautifully-built race engine to need rebuilding every 2000 miles or so, to maintain its power and reliability.

 

 

That really is more than even I normally bore people with

 

Alan

[Alec Pringle]

Hi Alan A,

 

IRS on a Wedge isn't an easy one. It was one of the options looked at for further development of the Le Mans car 1980-81, but as best I recall would have required a major redesign of the whole rear end chassis/shell - the kind of expenditure that ADA simply couldn't afford. The TR8 Drag Car, constructed a decade later, does incorporate some of the proposals of the time - I could envisage fitting IRS to that particular shell, although it currently runs a narrowed 9" Ford axle.

 

Other than that, I only know of two TR7V8s that were developed to an IRS spec in the latter 1980s, both utilising modified Jaguar components. One ran surprisingly well on the strip, but proved much less satisfactory on the road, severe understeer changing to snap oversteer. Sadly the owner lost his life in the car before he had resolved the problems. The other was intended as a sprint/race car, proved disastrously wayward in testing, and was dismantled - a course of action probably influenced by the aforementioned fatality.

 

Bottom line I think is that the TR7 was designed solely for a live axle at an early stage in its design programme, and it's less easy to add IRS to a monococque than to a car with separate substantial chassis.

 

Cheers,

 

Alec

[alan atkinson]

That's sort of what I figured.

Back when I was looking at a few "upgrades" for my 6, I ran across CWI (http://www.cwiinc.com/).

They couldn't narrow it enough to fit under a stock 6 shell, but it would fit inside a stock 8 outline.

 

I wondered if anyone had rejigged the car enough to actually be able to mount anything similar.

I was thinking it would take a tube frame extending back from the front subframe, with a cage to tie the whole thing together, which would be a fairly significant change, and hence limit the list of those who'd tried it.

 

I was wanting to tame that awful lurch when you hit a bump mid corner.

Snap oversteer is a little offputting though. Might as well buy a Porker and have some resale.

 

Anyhow sorry for the hijack, back to 300hp from a BOPR.

[300bhpton]

It's all too easy to fall into the trap of talking up the numbers when it comes to Wedges and V8s . . . .

 

The TR7 is a 40 year old design, originally intended for 100 horses and 120 pounds of torque, with the potential to accommodate a V8 with perhaps 50% increase in that power and torque. The 215 Buick V8 engine is a 1950s design - only a decade younger than the wetliner Vanguard lump, it went into production half a century ago.

 

If we consider dropping into a Wedge an engine developing triple the power and torque of the original design brief, it is unrealistic to expect the result to perform satisfactorily without major evolutions all round. Major evolutions, not just polybushing the suspension, adding uprated shocks and springs, and slapping Princess 4-pots on the front. A modest application of common sense ought to make that obvious.

 

I hear people argue that the works rally cars had 300 horses, so what's the problem ? Yes they did, occasionally, on a good day. They were also truly fearsome beasts, dancing on the edge of time, and strictly for the brave. Track cars of similar power are equally intimidating. Most folks who glibly natter about 300bhp Wedges haven't a clue what it's like to drive one. I've heard several accomplished and experienced competition drivers climb out of a first drive in a high power Wedge swearing never to repeat the experience, and casting compelling doubts upon the sanity of the regular pilots.

 

In period, TR7/8 period that is, the Rover 3.5 litre V8s in production form never put out more than 150bhp. Only the later Vitesse EFI models exceeded that - by some 25%. Pushing above 200bhp at the flywheel require some fairly serious engineering and expenditure, the law of diminishing returns kicks in with a vengeance. The more grunt, inevitably, the narrower the useable power band with a commensurate reduction in driveability. Not to mention the reduction in longevity. Agreed a larger capacity engine can achieve the power more easily, but the sheer torque is in itself a major problem to control.

 

It's common enough to see V8 Wedges advertised for sale claiming 200 and whatever horsepower. I have my doubts. Several years ago my wife put KEH on the Malvern rolling road, before we'd had the mobile tuning boys sort out the rough running that had developed. At 5Krpm on 7 cylinders it was supposedly making 200bhp at the wheels . . . I wish ! Yes it did put out 200+ at the wheels on the usual rollers, but at 6000rpm on all 8 cylinders. A discrepancy of 20-30% between a known quantity reliable chassis dyno (or engine dyno for that matter) and AN Other boy racer rolling road doesn't surprise me one bit. 200 horses at the wheels in a TR7 aren't that easy to keep in harness, even with properly sorted suspension, any lapse in concentration and the Wedge doesn't take prisoners.

 

For sure I wouldn't wish to start spending shedloads of dosh on creating a mega horse TR without having tried a few other examples first !!

 

Cheers,

 

Alec

 

I do recognise your name, so please don't take this as a direct insult, just an observation. But you're post does sound very much like an old duffer stuck in a time past. I see it a lot with the ALRC Land Rover Club - "EFI, what no no no, none of that modern stuff is any good at all"...... sort of attitude.

 

I do hear what you are saying, but think you are being way too over pretensions about it. If someone wants to build a 300hp TR7, then let them. After all it is their money.

 

And as said, there doesn't seem to be a shortage of high powered TR7's (albeit maybe few 300hp+ ones).

 

As for your claims of only ever intended 100hp - Tommy rot!! Lots and lots of cars are modified well above original factory specification. The TR7 is no exception to this rule, sure you need to modify the entire car, but I don't see it really being such an issue??

 

 

As for cars not making the HP claim, I agree. We all know TVR lied about their power outputs. But as I stated in my previous post. My car has been up against similarly powered vehicles with similar weight. If it was massively down on power then I doubt it would have performed so well, so sadly no documented proof, but logically it must have some meaning.

 

RX-8 231hp 1309kg

Z4 3.0i 228hp 1365kg

DC5 ITR 219PS 1170kg

 

 

I don't know how much my TR weighs, but I've seen figures as low as 1000kg for a 4 speed 2.0 and over 1200kg for a TR8. So I'd guess 1100-1200kg is not so far out. I quicker than the RX-8 and the BMW, and only slightly slower than the ITR.

 

 

I do know that this post might not win me any favours (but that's not my intent), but I feel you are being a little over the top and far too down in the dumps for what I presume is an enthusiasts website.

 

Sorry if it'd taken this too far OT though.

Edited September 28, 2010 by 300bhpton

[300bhpton]

 

As for V8 Heralds - I ran that past a pal who has spent many years working with over powered dragster small chassis Triumphs, knows more than most on what's feasible and what's not . . . his comments weren't repeatable. 'Nuff said.

 

Cheers,

 

Alec

 

Well it would seem at least 1 person doesn't agree with you though...

 

http://retrorides.proboards.com/index.cgi?board=readersrides&action=display&thread=80741

 

[Odd]

Not much Herald left in that one it seems...

New frame and only the outer skin parts. And they haven't kept it a Triumph made IRS...

That's not a Herald in my view.

Edited September 28, 2010 by Odd

[300bhpton]

Not much Herald left in that one it seems...

New frame and only the outer skin parts. And they haven't kept the Triumph made IRS...

That's not a Herald in my view.

 

Very true, but putting a different anything into something will make it different from the original. But isn't that the point??

[Stag powered]

Hi Alan,

 

good to hear from someone who knows just what they're talking about and has the t-shirts to prove it !

 

You're absolutely right, John Eales is the man with Rover V8s, at least if you want value for money.

 

 

Cheers,

 

Alec

 

When I had my 3.9 built by John Eales back in 1986 or '87 I think it cost somewhere in the region of £1100 for the short engine and cam which I thought was a bloody fortune back then, but if Red Arrow is still running it 23 or 24 years later considering the amount of abuse it took when I had it, then that is value for money

 

Neil

 

PS back in the 80's when rover V8 dyno shootouts were quite popular in the likes of Fast Car magazine, John Eales cars always had the lowest quoted power figures and always came out far better than quoted, and often far better than other engine builders quoting 30 or 40 bhp more. I was guaranteed 200bhp on SU's, and with a bit of development ended up with 225bhp on SU's, you can't say fairer than that!

[Alec Pringle]

Hi Neil,

 

John has always tended to quote conservatively - in contrast to some of his competitors ! Perhaps more to the point, he appreciates the desirability of a good torque curve, without which peak power outputs are somewhat meaningless - not to say ineffectual. A damn good engine builder, and also exceptionally good value.

 

Hi Odd,

 

there's nothing wrong with a properly designed scratchbuilt hotrod clothed in a Herald (or any other) skin . . . but as you say, it's a hotrod not a Herald. My earlier posts referred to an overpowered Herald, not a hotrod.

 

Hi 300bhp/ton,

 

you don't have a name, or have I missed it ? If so, my apologies.

 

I'm certainly not going to take umbrage at being called "an old duffer stuck in a time past" or at being "far too down in the dumps for what I presume is an enthusiasts website", but I would appreciate your extending the courtesy of reading carefully what I actually wrote ! I did not, for example, suggest "only ever intended 100hp" . . .

 

By "talking up the numbers" I refer to the optimism with which many owners and engine builders alike regard their Rover V8s - and I would claim at least some experience of reasonably powerful engines, Rover-based V8s and altogether more serious pieces of kit. I presume you too have had some experience of powerful V8s.

 

I hate to think how many times I've had discussions with enthusiasts eager to drop a mighty V8 into a Wedge, without having appreciated the extent of all the other modifications necessary to produce a reasonable end result. There's a break point somewhere around 150bhp at the rear wheels - beyond that, more effective upgrades elsewhere become appropriate. Then again somewhere around the 200bhp mark, above which a more radical approach all round is necessary. Too many owners have discovered this the hard way, and it seems foolish to perpetuate that particular tradition.

 

200bhp at the wheels of a TR7 or 8, a 60% increase on a stock TR8, depending on the gearing ought to be quite enough to see off a Mazda RX8, BMW Z4, Nissan 350 or Honda Integra in a straight line. Keeping any of them in sight into and through the bends is of course another matter ! Power is nothing without control, to borrow someone else's clever strapline.

 

300bhp at the flywheel, 250+ at the wheels, represents a 120% increase on what that stock TR8 has to cope with, or a 200% increase on a stock TR7. That's a large increment by any standard. A whole new ball game. It requires appropriate radical evolution all round - something too many folks have failed to appreciate in the past, sometimes with terminally unfortunate consequences. Think about it.

 

Cheers,

 

Alec

Edited September 28, 2010 by Alec Pringle