TVR 5 litre V* limitations
Discussion
Anyone know what the main limitation of the Rover V8 is...heads and valve sizes seem to be an issue??? Anything else obvious...just over 50bhp/litre is fairly naff even for a 100yr old design 
I guess, bar cam, induction, ignition etc, are new heads the real answer to big power increases?
Virgil.
I guess, bar cam, induction, ignition etc, are new heads the real answer to big power increases?
Virgil.
I'm not best qualified to help (other than having spent a few of my own hard-earned on my own RV8, and seen others do similar) but at least this reply gets the ball rolling for you...
Basically, the limitiation is the amount of cash you want to shell-out.
In 'stock' TVR form, the 5.0s generally give a realistic 260 to 270bhp at best. A few sensible tweeks - various permuations and combinations of cams, inlet-plenums, throttle body up-grades, re-chips and new injectors - can, for a fee, get you up to about 290bhp, perhaps 300 if you're very lucky.
To get north of 300 bhp starts to cost more money and generally involves something more substantial (i.e. engine-out) and, with throttle-bodies or carbs to replace the injection system, might get you as far as 340bhp (for a 5.2), but this is is getting into five figure budget territory... I believe. There are now also supercharging options - TVR Power offer one - but I have no first (or second) hand experience of these.
It is often said that instead of blowing a lot of dosh on cranking up the RV8 above 300bhp, that a Chevy LS6 or 7 engine transpolant is a cost effective consideration, particularly of you want over 400bhp.
TVR used to declare a figure of 450bhp for the 4.5 litre RV8 Tuscan Challenge engines, but if this figure is anything like as accurate as their publicly quoted road car figures (like 340bhp for a Griff 500
) then this again reinforces the received wisdom.
It'd be good to hear some more accurate £/bhp figures for the RV8 (and Chevy LS for that matter) from those who know...
Basically, the limitiation is the amount of cash you want to shell-out.
In 'stock' TVR form, the 5.0s generally give a realistic 260 to 270bhp at best. A few sensible tweeks - various permuations and combinations of cams, inlet-plenums, throttle body up-grades, re-chips and new injectors - can, for a fee, get you up to about 290bhp, perhaps 300 if you're very lucky.
To get north of 300 bhp starts to cost more money and generally involves something more substantial (i.e. engine-out) and, with throttle-bodies or carbs to replace the injection system, might get you as far as 340bhp (for a 5.2), but this is is getting into five figure budget territory... I believe. There are now also supercharging options - TVR Power offer one - but I have no first (or second) hand experience of these.
It is often said that instead of blowing a lot of dosh on cranking up the RV8 above 300bhp, that a Chevy LS6 or 7 engine transpolant is a cost effective consideration, particularly of you want over 400bhp.
TVR used to declare a figure of 450bhp for the 4.5 litre RV8 Tuscan Challenge engines, but if this figure is anything like as accurate as their publicly quoted road car figures (like 340bhp for a Griff 500
) then this again reinforces the received wisdom. It'd be good to hear some more accurate £/bhp figures for the RV8 (and Chevy LS for that matter) from those who know...
Whole design I think - for one thing, you can't get the valves any further apart, so you can't make them bigger... If you do, then you need new rockers and a new cam. The ports aren't ideal, but don't ask me what ideal is...
Mike (Mongoose) has managed 340 or so on his - I don't think he's gone for a crazy spec and it's certainly still 5 litres.
Mike (Mongoose) has managed 340 or so on his - I don't think he's gone for a crazy spec and it's certainly still 5 litres.
seasider said:
virgil said:
just over 50bhp/litre is fairly naff
Virgil.
Virgil.
You really need to give me a call one weekend
I certainly will...got mine RR'd at the weekend with the P&P Surry RR day...average for a 500...sh!te for a 5 litre aports car, especially as I know roughly what yours makes!
virgil said:
seasider said:
virgil said:
just over 50bhp/litre is fairly naff
Virgil.
Virgil.
You really need to give me a call one weekend
I certainly will...got mine RR'd at the weekend with the P&P Surry RR day...average for a 500...sh!te for a 5 litre aports car, especially as I know roughly what yours makes!
Aha..
To add to dnb's comments.
The heads definitely. The inlet ports are the worst design in the world ever! Alway more to it than simply this, but the ports have a negative port angle relative to deck face, they're also tall and narrow causing air flow seperation as it turns the corner into the bore. The exhaust ports are no better. Also the valves are not on the centreline of the bore reducing the valve diameter potential. Even the most talented engine builder/technician will struggle to get anything decent out of them.
The low-mounted camshaft is pretty awful too, necessitating long floppy pushrods that probably cause involutary variable valve timing when they go into resonance. The rocker arms look pretty flimsy too.
Still it's light(ish), compact, cheap, tough(ish), very easy to maintain and makes a very good noise.
Wildcat heads (based on the Buick V6 Grand National design) are the way to get decent power but just a little pricey! And you would have to change eveything else. Real Steel are supposed to be doing some new castings but I don't know much about them.
The heads definitely. The inlet ports are the worst design in the world ever! Alway more to it than simply this, but the ports have a negative port angle relative to deck face, they're also tall and narrow causing air flow seperation as it turns the corner into the bore. The exhaust ports are no better. Also the valves are not on the centreline of the bore reducing the valve diameter potential. Even the most talented engine builder/technician will struggle to get anything decent out of them.
The low-mounted camshaft is pretty awful too, necessitating long floppy pushrods that probably cause involutary variable valve timing when they go into resonance. The rocker arms look pretty flimsy too.
Still it's light(ish), compact, cheap, tough(ish), very easy to maintain and makes a very good noise.
Wildcat heads (based on the Buick V6 Grand National design) are the way to get decent power but just a little pricey! And you would have to change eveything else. Real Steel are supposed to be doing some new castings but I don't know much about them.
virgil said:
By this I presume you mean if you laid the head face flat on a table, the port would start to go up before it came down to the valve face? - not good!
Or it certainly looked like that when I had my heads off. Shouldn't criticise too much there are usually good reasons for it. Port width is restricted due to pushrod holes and probably the is height limited to rocker-arm position and overall engine height.virgil said:
wheeljack said:
To add to dnb's comments.
negative port angle relative to deck face,....
negative port angle relative to deck face,....
By this I presume you mean if you laid the head face flat on a table, the port would start to go up before it came down to the valve face? - not good!
However, it's hard to get a straight port with your valvetrain and rocker covers in the way
Straight ports have been done but at great cost and with a lot of fabrication. The humped port floor allows the air to remain in contact around the radius. Boosted.
My 500 has just made 319 bhp+360 ftlb on TCS dyno,its been built properly by Jamie(ex-TVR power) at Castle race engines,its standard apart from smooth bore inlet pipe and stump puller cam(Real Steel)and running fully mapped fuel and ignition,on the other hand my old 5.5 made 370 bhp and 430 ftlb!,but was a bit of a hand full(more rubber needed at the rear!) and the car is much nicer to drive day to day.You could get more by using Wildcat heads and throttle bodies but you are talking £3K+ and you could get a whole LS6 engine from the States for that.
To bo honest, I think talking about BHP is best left to pub conversation when addled with ale.
All, no, most TVRs have less power than the press releases claim, but they still go like stink.
I own a 390SE wedge, which is SUPPOSED to develop 275BHP (b*ll*x). I think that 230 - 240 is more like it, and even then, thats only on a crisp morning with nice cold air going into the engine.
Still puts a biiig smile on my face tho.
Ed.
All, no, most TVRs have less power than the press releases claim, but they still go like stink.
I own a 390SE wedge, which is SUPPOSED to develop 275BHP (b*ll*x). I think that 230 - 240 is more like it, and even then, thats only on a crisp morning with nice cold air going into the engine.
Still puts a biiig smile on my face tho.
Ed.
In the late Eighties I got into hillclimbing and at one venue,think it was somerset somewhere I witnessed some pretty extreme head mods on a lotus 7 type kit car using a rv8 3.5.
Basically the top of the ports were they bend were removed and the ports were straightened by extending the walls upwards and filling the bottom of the orignal port to make straighter ports,using thick ally sheetin a box construction,the port is moved up about 3/4`s of its height.
the rocker shafts are on raised platforms and the rocker cover face is raised,along with longer pushrods with volvo rocker shafts,this must mean that the valves were obviously longer,(from what,where?)
this results in a longer port which just goes straight down at a 45 degree angle,with no bends at all,mounted to this was a home made high rise type huffaker type manifold(look it up) with two 390 holleys.
dont know any other details of the engine and didn`t see it run but according to those who had seen it run and had been left in its dust,they were apparently very impressed.
Basically the top of the ports were they bend were removed and the ports were straightened by extending the walls upwards and filling the bottom of the orignal port to make straighter ports,using thick ally sheetin a box construction,the port is moved up about 3/4`s of its height.
the rocker shafts are on raised platforms and the rocker cover face is raised,along with longer pushrods with volvo rocker shafts,this must mean that the valves were obviously longer,(from what,where?)
this results in a longer port which just goes straight down at a 45 degree angle,with no bends at all,mounted to this was a home made high rise type huffaker type manifold(look it up) with two 390 holleys.
dont know any other details of the engine and didn`t see it run but according to those who had seen it run and had been left in its dust,they were apparently very impressed.
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