Best route for 300bhp+

[Paul Heritage2]

Been reading a lot of documentation recently and looking for a fast road/reliable setup to give 300-350bhp. My current assumption is the late 4.6l V8 engine, but wondered about the best carburation. Is it best to go EFI or 4-barrel? The former is the standard Land Rover/Range Rover, the latter being many different options. As a fast road car, would a dual-port manifold (jwr), with double pumper offy and (up to) 600cfm holley be the best route? or webers?

[anthonyt]

Despite what some will say, you wont bolt your way onto 300BHP, (unless you buy an engine that has been built to produce that).

 

Unless you are planning to compete seriously on the track i wouldn't recommend that amount of HP as the car will be difficult to drive in anything but completely dry conditions if the current engine really has 195HP it should already be twitchy in the wet.

 

If you still want to go down that track to make the car reliable and driveable for the road you will need to have head work done, a good electronic ignition, heavy duty plug leads, extractors, a better cooling (read larger radiator) system, oil cooling, a limited slip differential a big fuel pump, a properly set up suspension and sticky tyres (i use 225,50,15 Yokohama A048R all round for the street). For driveability a EFI is best (suggest Motec or Haltec controller) for simplicity and reliability a Holley and an Edelbrock manifold cant be beaten but fuel economy is horrendous. You wont need a 600CFM holley that will be too big and you will have to choke it down.

 

A slightly worked 4.6 engine will help greatly towards your goal but without most of the rest you will have lots of problems and ongoing expenditure as you work your way through the necessary improvements.

 

Alternatively you could have a nitrous kit fitted to the existing engine and hope it doesn't blow up.

 

Good luck with your project sorry if the above seems negative but its better to find out now.

[Alec Pringle]

Hi Paul,

 

300bhp in a Wedge isn't a road car, it's a competition car, pure and simple. It might be road legal, it certainly won't be a pleasure to drive. 300 horses from a 3.5 litre is pushing the limits of driveability as far as a rally car is concerned, and an absolute swine to drive between stages. You wouldn't believe how fast the transmission expires . . . .

 

Sure it's easier to get the power out of a bigger base lump, but the inherent torque will eat boxes and axles like there's no tomorrow, even using a Salisbury axle. In any case, the wheelbase/track/suspension relationship doesn't lend itself to that sort of grunt, it isn't up to the job - not without fundamental re-engineering. That implies tens of thousands of pounds.

 

If you want a road car with 300+bhp, buy something that's designed for the job ! Not a Wedge !

 

Cheers,

 

Alec

[Stag powered]

Been reading a lot of documentation recently and looking for a fast road/reliable setup to give 300-350bhp. My current assumption is the late 4.6l V8 engine, but wondered about the best carburation. Is it best to go EFI or 4-barrel? The former is the standard Land Rover/Range Rover, the latter being many different options. As a fast road car, would a dual-port manifold (jwr), with double pumper offy and (up to) 600cfm holley be the best route? or webers?

 

A good few years ago I sold an early 3.9V8 (JE Motors 3907cc)to the guy who used to be the TR7 Registrar (cant remember his name). He wanted it for his wife and from what I remember fitted it with an auto box, sadly it scared her witless and he ended up selling the car, This engine only had 226bhp, but the torque was what caused the problems. I had this engine fitted to a Toledo, and with a 3.45 diff it would spin the wheels in the wet in 5th gear at 1200rpm with just a touch of throttle.

I started doing a bit of drag racing (this was late 80s, early 90s) and fitted a 248 cam which actually made it quite driveable in the wet as not a great deal happened below 4500rpm, then all hell would break loose, even in the dry. I think it had about 270bhp in this spec based on the terminal speeds on the quarter mile, but I couldnt get all the power down until I was in 4th, so it may have had a bit more. The Toledo is probably a bit lighter than the TR7, but the same principals apply. The 3.5 engine was a completely different animal, I had one with the same spec as yours before I fitted the 3.9

Oh yeah, I also used to destroy a gearbox every other year(usually 5th gear) and the TR7 axle had a habit of firing its planet gears through the diff casing hence the need for a limited slip diff, Though oddly the Dolomite Sprint diff didn't suffer from the same problem, I suspect the spindly halfshafts were winding up and taking the shock loadings off the diff

If you want to use the car in the wet (the Toledo was my only car ,12000 miles/year)I wouldnt go past a 3.9 unless you use a fast road cam or fit some form of traction control which sadly hadn't been invented (affordably) when I had the Toledo

Neil

[Odd]

The last two postings give good advise!

I've got a standard spec '97 Disco 3.9 efi in my TR8 directly out of the LR (with what? 185hp+235lbft or so?) - and it sometimes scares me white when in the wet. Negotiating a roundabout in rain is outright scary on occasion, the rear comes whipping past you without even a single bit of pre-warning! In second, third and sometimes fourth gear - with a TR8 rear axle ratio and 185/70 tyres. I think a 3.45/3.90 and wider threads would be worse yet in the wet...

[alan atkinson]

Been reading a lot of documentation recently and looking for a fast road/reliable setup to give 300-350bhp. My current assumption is the late 4.6l V8 engine, but wondered about the best carburation. Is it best to go EFI or 4-barrel? The former is the standard Land Rover/Range Rover, the latter being many different options. As a fast road car, would a dual-port manifold (jwr), with double pumper offy and (up to) 600cfm holley be the best route? or webers?

 

 

An engine swap with something designed to output 300hp might be a good start.

300hp from a BOPR isn't going to give you a tractable car unless you go forced induction.

 

An LS series is nigh on the same size as the 215, weighs only a little more and has gobs of power stock.

You can add a T5 (no tunnel mods) or a T56 (hammer mods) to the back of it easily, and then get a custom rear end based on something like a Ford 8.8.

 

US prices for the lot would be around 10k USD, so figure around $15k for the conversion.

Which is still less than a monster 215 motor and a new rear end, with a (still marginal) 5 speed.

 

Of course a (real) 200rwhp car is still quite a lot of fun, and quite do-able.

Upgrade the suspension and brakes while you are in there though...

Edited August 26, 2010 by alan atkinson

[jothecat]

My convertible used to push out 330 at the wheels: this was measured on the old rolling road (dialtype) at the international about 4 years ago. I changed the exhaust system so now it's quiter and only about 272 at the wheels but the torque is amazing.

It runs a 4.6 with a race camshaft, Holley, edelbrock, and a stage 2 head ( I think). The rad is a custom built 5 core to keep it cool. Easy to drive over 45 mph but lumpy around town. Fuel consumption 25 - 30. Brakes are revington kit and stop like a 2010 car. It takes a lot of work and a lot of dosh to get 300 bhp. But it puts a huge smile on your face!

[300bhpton]

Been reading a lot of documentation recently and looking for a fast road/reliable setup to give 300-350bhp. My current assumption is the late 4.6l V8 engine, but wondered about the best carburation. Is it best to go EFI or 4-barrel? The former is the standard Land Rover/Range Rover, the latter being many different options. As a fast road car, would a dual-port manifold (jwr), with double pumper offy and (up to) 600cfm holley be the best route? or webers?

 

That kind of HP from an RV8 will not be cheap or easy.

 

Heads kind of limit the power, hence a 3.5 with the right cam and supporting mods can make very similar PEAK numbers to a 3.9 or 4.3 (but evidently less torque and less power under the curve).

 

I too have looked into making more power from an RV8. If you have the money:

 

-Then largest displacement you can get (4.6, or 4.8 from a stroked 3.9 or maybe even a 5.0-5.3) some really good heads, silly cam, other supporting mods and a full EFI setup using something like Megasquirt.

 

But this will take loads of money and still likely struggle to break a true 300hp, although even with 280hp a 1000=1200kg car won't be a slouch.

 

 

Other options include supercharing or turbo charging. There are TVR kits for Eaton blowers or you could fab one up. Similar story with turbo's, there is someone who makes turbo manifolds for the RV8. Lastly, Google STS Turbo's. They make rear mount systems in the US. A similar idea could be used on the RV8 in a TR.

 

Boost is a good way to get more power, but to make it last and get it to make the power you want, you are still likely looking at a fair few ££££.

 

 

Nitrous oxide. This is probably the best bang per buck option. £1500 should get you something that can offer 100-150hp on top of a standard motor. So taking a 4.6 easily up to the power levels you want. Downside is its only a performance gain at full throttle.

 

 

Lastly how about engine swaps? Something I've been looking into is swapping in a Lexus LS400 DOHC V8 in. Stock they make around 270hp with full emissions, so couple it with a few bolt on mods and it'll likely make more power than a built RV8. And I think probably a cheaper total cost to get running too.

[Red Arrow]

Hi I am the new owner ( about four weeks) of a TR7V8 with your engine in it, you sold the engine to a John Elliot. I read with interest the "fun you had with this unit in your Toledo. The complete TR7V8 has been owned by two other members of our group. The 7V8 seems to have the same characteristics as your Toledo and I have experienced the performance in the wet when I collected the car from its previous owner ( it was p***ing down). But its great fun driving up the road from side to side with on coming traffic!!! The diff is now a 2.84 unit on a 5speed box (with all gears connected)and although livley it seems pretty controlable, but I have a question

I cannot be sure as I am not fully experienced with V8s --but was the cam you fitted still in the engine when it was bought from you as currently above 4500 all hell is only slightly escaping, and just as amatter of interest what carb did you have on the engine. Would be grateful for any info on this.

A good few years ago I sold an early 3.9V8 (JE Motors 3907cc)to the guy who used to be the TR7 Registrar (cant remember his name). He wanted it for his wife and from what I remember fitted it with an auto box, sadly it scared her witless and he ended up selling the car, This engine only had 226bhp, but the torque was what caused the problems. I had this engine fitted to a Toledo, and with a 3.45 diff it would spin the wheels in the wet in 5th gear at 1200rpm with just a touch of throttle.

I started doing a bit of drag racing (this was late 80s, early 90s) and fitted a 248 cam which actually made it quite driveable in the wet as not a great deal happened below 4500rpm, then all hell would break loose, even in the dry. I think it had about 270bhp in this spec based on the terminal speeds on the quarter mile, but I couldnt get all the power down until I was in 4th, so it may have had a bit more. The Toledo is probably a bit lighter than the TR7, but the same principals apply. The 3.5 engine was a completely different animal, I had one with the same spec as yours before I fitted the 3.9

Oh yeah, I also used to destroy a gearbox every other year(usually 5th gear) and the TR7 axle had a habit of firing its planet gears through the diff casing hence the need for a limited slip diff, Though oddly the Dolomite Sprint diff didn't suffer from the same problem, I suspect the spindly halfshafts were winding up and taking the shock loadings off the diff

If you want to use the car in the wet (the Toledo was my only car ,12000 miles/year)I wouldnt go past a 3.9 unless you use a fast road cam or fit some form of traction control which sadly hadn't been invented (affordably) when I had the Toledo

Neil

 

[300bhpton]

Despite what some will say, you wont bolt your way onto 300BHP, (unless you buy an engine that has been built to produce that).

 

Unless you are planning to compete seriously on the track i wouldn't recommend that amount of HP as the car will be difficult to drive in anything but completely dry conditions if the current engine really has 195HP it should already be twitchy in the wet.

 

If you still want to go down that track to make the car reliable and driveable for the road you will need to have head work done, a good electronic ignition, heavy duty plug leads, extractors, a better cooling (read larger radiator) system, oil cooling, a limited slip differential a big fuel pump, a properly set up suspension and sticky tyres (i use 225,50,15 Yokohama A048R all round for the street). For driveability a EFI is best (suggest Motec or Haltec controller) for simplicity and reliability a Holley and an Edelbrock manifold cant be beaten but fuel economy is horrendous. You wont need a 600CFM holley that will be too big and you will have to choke it down.

 

A slightly worked 4.6 engine will help greatly towards your goal but without most of the rest you will have lots of problems and ongoing expenditure as you work your way through the necessary improvements.

 

Alternatively you could have a nitrous kit fitted to the existing engine and hope it doesn't blow up.

 

Good luck with your project sorry if the above seems negative but its better to find out now.

 

 

Hi Paul,

 

300bhp in a Wedge isn't a road car, it's a competition car, pure and simple. It might be road legal, it certainly won't be a pleasure to drive. 300 horses from a 3.5 litre is pushing the limits of driveability as far as a rally car is concerned, and an absolute swine to drive between stages. You wouldn't believe how fast the transmission expires . . . .

 

Sure it's easier to get the power out of a bigger base lump, but the inherent torque will eat boxes and axles like there's no tomorrow, even using a Salisbury axle. In any case, the wheelbase/track/suspension relationship doesn't lend itself to that sort of grunt, it isn't up to the job - not without fundamental re-engineering. That implies tens of thousands of pounds.

 

If you want a road car with 300+bhp, buy something that's designed for the job ! Not a Wedge !

 

Cheers,

 

Alec

 

 

Tell me, have you guys never heard of a TVR?? They seem to do rather well with a similar setup?

 

BTW - alec I don't believe the OP was asking about tuning a 3.5 litre engine

 

 

300+hp will deserve respect for sure. But there is no reason why it can't be usable. Cars are really quite clever, they have this device that allows you to vary the amount of power it makes......... it's called an accelerator pedal, lol

 

[Odd]

I thought the TVR had a longer wheel base, among other improvements (over a TR7)...

[Stag powered]

Hi I am the new owner ( about four weeks) of a TR7V8 with your engine in it, you sold the engine to a John Elliot. I read with interest the "fun you had with this unit in your Toledo. The complete TR7V8 has been owned by two other members of our group. The 7V8 seems to have the same characteristics as your Toledo and I have experienced the performance in the wet when I collected the car from its previous owner ( it was p***ing down). But its great fun driving up the road from side to side with on coming traffic!!! The diff is now a 2.84 unit on a 5speed box (with all gears connected)and although livley it seems pretty controlable, but I have a question

I cannot be sure as I am not fully experienced with V8s --but was the cam you fitted still in the engine when it was bought from you as currently above 4500 all hell is only slightly escaping, and just as amatter of interest what carb did you have on the engine. Would be grateful for any info on this.

 

The engine was fitted with the original JE Motors 101 cam when I sold it, which they persuaded me was a much better choice (correctly) than the 214 cam I had fitted to the 3.5 that preceeded it. As to the car being pretty controlable, don't forget you have a 2.84 diff, I was using a 3.45 so you are effectively 1 gear higher all the time. I was using a 3.45 as it was best off the line when drag racing (in 2nd). With a 3.08 it span in first and bogged in 2nd, and 2.84s were not readily available in scrapyards at the time (the SD1s were still being built then)

To begin with I was using the standard SU's. With KN filters and cold air ducting I could get 215bhp and 27 mpg, or with a change of needles 225bhp but only 22mpg, so I used to swap needles when I got to the race track, and back again when I went home. I switched to a 390 holley that didnt gain me any horsepower, but I did get full power and economy at the same time. I could probably have got more if I could have got room to duct cold air to the holley, but the engine bay was just too full of engine.

When I fitted the 248 cam I changed to a 465 holley, there was some debate at the time as to wether this was too big, but I never had any problems with it. If I recall correctly, before I fitted the 248 cam I fitted big valve heads with the 101 cam. This turned out to be a bad idea. With the standard heads the toledo would just make 140mph on the motorway(no speed cameras back then Having fitted the big valve heads I had to lift off at 140mph to avoid over revving, it was obviously making a lot more power, unfortunately the heads destroyed the bottom end torque and actually made my quarter mile times worse as a result. To add insult to injury the fuel consumption got worse as well. At this point I decided to go the whole hog and fit the 248 cam, and it all came good (apart from the fuel consumption)

When I stopped racing I refitted the 101 cam, standard heads, and SU's and carried on using it untill I sold it to John Elliot. The 248 cam and big valve heads were sold to someone who fitted them to a TR7 V8 race car

Neil

[Red Arrow]

[quote name='Stag powered' timestamp='1284752521' post='185369 Thanks Niel for the info, that explains a lot in terms of where it is now, very grateful for that. So as I see it now has the standard heads and manifold and it now sports an Edelbrock four barrel Performer series, which has served the previous two owners of the car well. Will take the car to get it tuned in as it a little lumpy at times. Thanks again for the info.

The engine was fitted with the original JE Motors 101 cam when I sold it, which they persuaded me was a much better choice (correctly) than the 214 cam I had fitted to the 3.5 that preceeded it. As to the car being pretty controlable, don't forget you have a 2.84 diff, I was using a 3.45 so you are effectively 1 gear higher all the time. I was using a 3.45 as it was best off the line when drag racing (in 2nd). With a 3.08 it span in first and bogged in 2nd, and 2.84s were not readily available in scrapyards at the time (the SD1s were still being built then)

To begin with I was using the standard SU's. With KN filters and cold air ducting I could get 215bhp and 27 mpg, or with a change of needles 225bhp but only 22mpg, so I used to swap needles when I got to the race track, and back again when I went home. I switched to a 390 holley that didnt gain me any horsepower, but I did get full power and economy at the same time. I could probably have got more if I could have got room to duct cold air to the holley, but the engine bay was just too full of engine.

When I fitted the 248 cam I changed to a 465 holley, there was some debate at the time as to wether this was too big, but I never had any problems with it. If I recall correctly, before I fitted the 248 cam I fitted big valve heads with the 101 cam. This turned out to be a bad idea. With the standard heads the toledo would just make 140mph on the motorway(no speed cameras back then Having fitted the big valve heads I had to lift off at 140mph to avoid over revving, it was obviously making a lot more power, unfortunately the heads destroyed the bottom end torque and actually made my quarter mile times worse as a result. To add insult to injury the fuel consumption got worse as well. At this point I decided to go the whole hog and fit the 248 cam, and it all came good (apart from the fuel consumption)

When I stopped racing I refitted the 101 cam, standard heads, and SU's and carried on using it untill I sold it to John Elliot. The 248 cam and big valve heads were sold to someone who fitted them to a TR7 V8 race car

Neil

 

[Incony]

At the Moment i am very interested in Rover V8 engines, and since i am putting one in a Triumph Herald, This TR register is

well linked to all three. That is why i am posting.

 

The TR8 real axle and diff arrangement particulary, but also i was very interested to read Stagpowered`s input, since my Rover engine is a 3.9 (rebore from 3.5 - 30,000 miles ago) , with a fast road cam, uprated mechanicals, uprated 5 speed manual gearbox and clutch, using a weber edelbrock manifold/ carb assembly, and produces about 230 BHP at 5400 RPM.

 

you can read, my input - about the engine, and what my intentions are here:

Herald V8

 

i will be the first to admit, that i dont know everything, i am learning.

 

Particularly, as Stagpowered says, i know the SDI that the Engine is in right now, will spin wheels in first gear no problem, and that is with the 3.08 final drive ratio on 15 inch wheels. The torque curves i have seen of similar engines used in the Rover Discovery, show me thats its a very broad and level curve.. there is near full torque all the time... at any revs..

 

So to read how Stagpowered has encountered and dealt with a similar setup ,is excellent to see, TY..

 

The main problem for me, is the rear axle, and i have been drawn to considering if i could use the TR7/8 axle arrangement because, on paper, its only about 10 cm wider? than the triumph herald, is available from Rimmers, and has a 3.08 Diff.

 

That would mean that if i can modify the Herald Chassis to take it, the TR8 axle is able to do the same as the Rover SDI, which is over 20 cm wider.. and i cant get the Rover axle shortened.. no one can remake the splined shafts.

 

So.. because i want to know more about the layout of the TR7/8 axle, diff and suspension, can anyone point me to a diagram?

 

Regards

 

Incony.

[anthonyt]

Tell me, have you guys never heard of a TVR?? They seem to do rather well with a similar setup?

 

BTW - alec I don't believe the OP was asking about tuning a 3.5 litre engine

 

 

300+hp will deserve respect for sure. But there is no reason why it can't be usable. Cars are really quite clever, they have this device that allows you to vary the amount of power it makes......... it's called an accelerator pedal, lol

 

 

300BHPTon TVR has a different wheelbase amongst other difference.

 

I have owned an occasionally road driven track TR8 convertible since 1992 with a 4.5l (stroked 3.5) engine (and 960kg) that depending upon tune and how much i want to spend on 106 octane racing fuel puts out well in excess of 300HP (real ones proven on a dyno).

 

The car is virtually undriveable in the wet due to the combination of torque, wheelbase and track, despite trying special wet racing tyres. yes a light foot will ensure you don't collect a wall or another car but it isn't fun.

 

With respect to all others concerned i think that Alex Pringle is probably the best qualified person on high powered TR7's and 8's, much misinformation is spread by "specialists" re their go faster bits, the truth is that few rover TR v8's put out anywhere near 300HP reliably, fewer still can be driven to their full potential because the rest of the car is rarely sorted to allow that to be done, then it takes some time to understand the car well enough to use 300HP.

[Alec Pringle]

Hi Incony,

 

I wouldn't even think about putting a V8 into a Herald chassis. It isn't a viable option - not short of massively reinforcing the chassis and adding a full cage - and that's only fit for drag racing. End of discussion. Period. Sorry to have to be blunt, but that's life.

 

Hi Anthony,

 

thanks for the kind words, but I'm afraid you're perhaps in danger of overestimating my strictly limited expertise. Yes OK I've driven the LM Car and the Drag Car, a few works rally cars then and now, and a few other quick V8s - but I'd reckon some of the V8 racers have a lot more experience than I can offer . . . .

 

Rolling road figures I treat with boundless cynicism, as I've explained in previous threads - unless, that is, we're discussing known quantity chassis dynos for final tuning after setting up the engine on an engine dyno of known calibre. Anything else is comparing apples and pears. In a TR7/8, a genuine 300bhp at the flywheel, whatever the engine capacity, is extremely difficult to drive on the road in the dry, let alone in the wet. A pleasure it most certainly is not. But you know that as well as I do !!

 

But to be fair, life moves on, there are always new avenues to be explored, fresh viewpoints on the old problem of how to make a Wedge handle. It's one heck of a strong shell, there's a lot can be done with it, and far be it from me to dissuade another generation of enthusiasts from trying to make a better job than their predecessors ! More power to their elbow, but for heaven's sake don't reinvent the wheel - take a long hard look at what's gone before, and what did and didn't work, and learn from that.

 

Cheers,

 

Alec

[300bhpton]

300BHPTon TVR has a different wheelbase amongst other difference.

 

I have owned an occasionally road driven track TR8 convertible since 1992 with a 4.5l (stroked 3.5) engine (and 960kg) that depending upon tune and how much i want to spend on 106 octane racing fuel puts out well in excess of 300HP (real ones proven on a dyno).

 

The car is virtually undriveable in the wet due to the combination of torque, wheelbase and track, despite trying special wet racing tyres. yes a light foot will ensure you don't collect a wall or another car but it isn't fun.

 

With respect to all others concerned i think that Alex Pringle is probably the best qualified person on high powered TR7's and 8's, much misinformation is spread by "specialists" re their go faster bits, the truth is that few rover TR v8's put out anywhere near 300HP reliably, fewer still can be driven to their full potential because the rest of the car is rarely sorted to allow that to be done, then it takes some time to understand the car well enough to use 300HP.

 

Point taken , although I'm not sure there is a shortage of high HP TR7/8's, which would kind of suggest they aren't all that bad.

 

I admit my car is lacking a few ponies to directly compare, but it's been on a dyno making a tad under 200rwhp from a 3.5RV8. Which would seem consistent with it's performance as it'll outrun a 231hp RX-8 and a 3.0i Z4 and stick pretty darn close to a JDM spec DC5 Integra Type R (with at least exhaust mods) in a straight line.

 

I wouldn't have said it was a handful to drive though. Would be keen to see what a 300hp one is like.

[Incony]

Smiles. i understand.. but its already been done, several times now.. i am not the first..

 

Its why i know its posible.. and how.. even in a herald estate..

 

But certainly, i respect judgement..

 

Even if the judgement hasnt seen...

 

 

But, i will let you know right now that its not " end of story", time waits for no one..

 

Imagine, that one had said nearly 100 years ago, that the titanic could not sink.. folks said that... it sunk..

 

Imagine that one had said 40 years ago, that man would not stand on the moon.. folks said that.. man stands on the moon..

 

Look up technological singularity... its the path i think we all take.. remember that in a hundred years time..

 

V8 Herald.. here i come.

[Stag powered]

Point taken , although I'm not sure there is a shortage of high HP TR7/8's, which would kind of suggest they aren't all that bad.

 

I admit my car is lacking a few ponies to directly compare, but it's been on a dyno making a tad under 200rwhp from a 3.5RV8. Which would seem consistent with it's performance as it'll outrun a 231hp RX-8 and a 3.0i Z4 and stick pretty darn close to a JDM spec DC5 Integra Type R (with at least exhaust mods) in a straight line.

 

I wouldn't have said it was a handful to drive though. Would be keen to see what a 300hp one is like.

 

At the end of the day it is torque that causes all the problems. A small very high revving engine can make silly power at silly revs but can be quite easy to drive when not pushed hard. By the time the 300bhp has reached the wheels though, the effect will be the same, as the lower gearing needed by a high revving engine will multiply the torque up to the same level.The tyres have no idea what combination of revs and torque was required to arrive at 300 bhp. I would be interested to know how a modern 4 valve (or 5 valve) per cylinder V8 drives at "normal" road going rpm as I suspect that peak torque would be lower for the same maximum horsepower as the old 2 valve pushrod V8s

The injected Stag engine I have in my TR250 is putting out 216bhp according to the rolling road at malvern this year but is doing that at 6500rpm, and peak torque is only 200lbft.

When the 3.9 in the toledo was putting out the same power it was horrible in the wet, yet the Stag engine does not put out enough torque to cause too many brown trouser moments, but can still deliver the goods at high rpm.I suspect the independant suspension on the TR also makes a difference though as the torque reaction from the propshaft will always try to lift the nearside rear wheel on a live axle.This is why drag race cars are nearly all left hand drive, it adds the drivers weight over the wheel most prone to spinning

Neil

[Paul Heritage2]

Hi Guys,

 

Some interesting points being made that I hadn't really contemplated. My current TR7V8 has 200bhp and is relaxing to drive around town and didn't think the extra horses or torque would make a TR7 potentially less enjoyable to drive.

 

Since my original post (sorry for the delay in joining back in), I have been reading various articles on V8 engines and carburation and recently looking at a TVR 450SE engine (320BHP) which would seem to be the 'cheapest' way to get a well-built/designed engine, as well as more modern EFI, all based on the Rover V8.

 

Perhaps a more reserved option may be a nice compromise like a TVR 390SE engine (275BHP)

 

Paul.

[Alec Pringle]

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

[Paul Heritage2]

Experience is obviously key with what the TR7 can cope with - I'm not currently able to really add much here, although I certainly wouldn't consider much over 200bhp without major work.

 

On a side issue, I am currently updating my website at www.triumph-cars.co.uk with all things TR7 so adding stuff weekly now that I have an easier means of publishing.

 

Cheers, Paul.

[Odd]

Well said indeed, Alec!

 

I find the (original - just as out of a '97 Discovery V8i) 185 hp and 230 lb/ft of my 3.9 efi engine, sitting in a well kept TR8 body, making it a meen bastard on non-straight roads when in the wet - since this engine was built by LR to be a torqey engine (pulling an oversize estate van around) at bearable engine rpm = more torque than top rpm power... Just as Alec stated: the Wedge "doesn't take prisoners", it kills you instantly - if you're not awake every split second... And having something like 90-100% more would only make it worse in the wet. Sure, on a straight run down a dry 1/4-mile stretch (without boulders, trees, chicks with prams etc lining the edges) it could be fun - if one have the ability/skill to shift gears quickly enough. But for a roadgoing car; aiming for 200 hp and say 250 lb/ft is still asking for trouble...

[alanprice]

Fascinating subject, it takes me back to when I first got in to TR7 V8's in the early 90's. Good (if a little surprising) to see that there is still interest. Back then I was besotted by hp and had an engine built by one of the leading V8 converters to their 3.9 Stage 4 spec, 270 whopping bhp claimed. Imagine my fallen crest when it rolling-roaded at 170 at the rear wheels, about 220 corrected! I barely listened to the operator who told me it was a very sweet engine and perfect for the car (I think torque was 220 lbft). So it would be two-faced of me to advise the OP not to bother, but it backs up the previous wise words that 300bhp is indeed hard to get reliably. I doubt the TVR 390SE ever put out more than my 220, for instance.

 

Even my race engine puts out only 80bhp/litre and needs 6700rpm; a massive further investment (£4k) would be needed in inlet system and ported heads to get up to 90/litre. Air flow in the heads is the problem; as Alec says, it's an old engine. Mine was built by JE Developments (that's John Eales himself, plus son Richard) and I feel that he remains the leading expert in these engines. I find my engine to be relatively mild and useable for a race engine, but on the road? No thanks! I can at least say my race car is predictable in the wet, but not much fun as I have to back off so much - and road conditions are anything but predictable. If there's fuel or oil on the track, a nice man puts out a red/yellow flag to warn me; unseen whilst powering out of a roundabout, which end of the car am I going to crunch, perhaps both?! Also an incredible amount of time, money and effort has been put in to modifying the running gear on my car - if you saw it, you wouldn't recognise much as being TR, either layout or component-wise, so that's of limited relevance for the road, except to say that it's VASTLY superior to standard.

 

Sorry this doesn't directly answer the OP's questions, but you can see some wise heads like Alec have warned that a 300+bhp road car might just prove to be 20% thrill, 40% frustration and 40% terror. Remember that whatever power you get, eventually the novelty wears off and you look for other qualities in the car. I know more power won't significantly improve my lap times, the car needs further development on the chassis - and a better driver!

 

Nevertheless I can recommend JE for no-frills, reliable, lasting (not just for 5000 miles) power that overcomes the inherent weaknesses in the Rover V8 design. Like anywhere else, the power doesn't come cheap, but he has been working with these engines for over 30 years.

 

LOL

Alan

[Alec Pringle]

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.

 

One small point I should have mentioned previously - no one should even think about going past 200bhp at the flywheel without a proper rollover bar in the back to stiffen things up. Just ask my wife what happens if you lose traction changing from 3rd to 4th knocking on the ton . . . . if it wasn't for the a/r bar she wouldn't be telling you ! If you go much more than that, power or torque wise, a full cage is mandatory for anyone other than a kamikaze candidate.

 

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